Advice needed on first cab build. Smaa single speaker type.

[tonequester]

tonequester here. I'm new to this part of the forum. A little backgroung info on what i'm trying to do. I'm working on a way to "re-amp" a Blackstar HT-1R, 1 Watt, studio/practice amp, through a solid state (kit built) power amp with an out put of 20-30 Watts. I'll be using the 4-16 ohm speaker output jack on the back of the "tube amp". I have an Eminence, 150 W., 32 Ohm speaker. If buy another of these, and hook them in parallel I will have 16 Ohms, which would work with the Blackstar, but I'm going to re-amp with a s.s. power amp. Do I need to make sure the power amp is designed to work with EXACTLY 16 Ohms. Also, what would be considered a "good" size for the cabinet, with two 15",150 Watt speakers. Open back or closed ? Any Opinions welcome, thanks.......tonequester.

[Chuck H]

JMHO, but... Chasing the usefulness of that 32 ohm speaker by buying another one is a waste of money. You could probably get a well known and respected, proper guitar amp speaker for the same price. That is, unless you've heard this 32 ohm speaker and like it's tone above all others. The SS amp DOES need to be designed with the intended ohmage in mind IF you want to get the full wattage out of it. If you run the SS amp into too low a load it may over dissapate. If you run it into too high a load it won't deliver the intended power. The cabinet size is somewhat pedantic WRT guitar amps. Accidental resonances and peaks are part of why certain cabinets sound good with certain amps. Remember that a guitar amp is intentionally coloring the sound. And absolutely NOT trying to reproduce it accurately. That said... There are cabinet designs for roughly 30 watts that are known to sound a certain way for guitar tone. A VOX AC30 with a pair of Celestion Blues (or cheaper, but not considered as good, a pair of V30's) comes to mind. There are also many 1x12 cabinet designs that are very popular and should work well for amps from 20W to 50W.

Point is... If your going to spend money on a speaker for guitar, buy a guitar speaker. Don't try to make the 32 ohm speaker useful by correcting it's load with another 32 ohm speaker (unless you like that speaker, as noted).

Another note... If your feeding signal from the "host" amp to the supporting amp properly, the tube amp should be oblivious to the needs of the SS amp. So the SS amp and it's speaker load is the only formula you need to consider.

[tonequester]

tonequester here.



Thanks Chuck. Your reply is as always, based in common sense. Sometimes i try to "think' to much, and in doing so forget common sense. The only strange thing about the 32 Ohm speaker is that I'm sure that I got it as a guitar amp speaker. It may have been someones mistake,but it came from an amp that was parted out. I don't even recall what the amp was. I guess that I should have known that 32 Ohms would not be used for a stock speaker. after considering your reply, I am now inclined to perhaps buy two more of the Weber speakers that I have used to replace the stock Blackbird in my HT-1R. I really like the tone, and their price is hard to beat. I can get a couple of 12" Alnico speakers(guitar) in 4 or 8 Ohms for about $50.00 a piece. Weber claims that all 15" speakers suffer from "cone rub' at high volume. I have no idea if this is hype or true, but a couple of 12's would probably do me fine, and fit a cab that is not too big to lug around. I figured that the s.s. amp and the load would be the main consideration, thanks for confirming that. I'm checking out multiple methods of matching tube, s.s., and speaker cab. It seem that depending on what method one chooses, that alone can run anywhere from a few bucks to $500.00. I figure you can guess which direction I will try to begin with. I know that a simple load resistor is the cheapest way to go, with probably the least in positive results. The Ultimate Adaptor appears to do everything including wiping your nose,
but at $499.99 it exceeds the cost of the tube amp kit and the s.s. kit amp combined. I'm looking at the "middle road". When I find a possibility, I'll definitely post it. I know that I need something that not only will satisfy impedance matching needs, but also give some control over signal strength. Those are things that the Ultimate Adaptor apparently does among other things. Thanks again for the reply. I always look forward to your comments as you are quite good at blending "theory" with common sense. You like me, don't like to waste money if it is
possible not to do so. Have a great day Chuck H ! tonequester.

[Chuck H]

I think your talking about the Ultimate Attenuator. Also known as the Ho attenuator as this is the name of the designer and a name they were also sold under by him. This next bit is a very important consideration. I met the Ultimate attenuator guys at the 2009 NAMM show. I loaned them an amp and they loaned me an attenuator. Both to the benefit of our personal exhibits since there was an 85dB limit on sound levels. The attenuator I had brought (a cheapy L-pad thingy) sounded like crap and the amp they brought (and old HiWatt) did too. Both booths sounded much better for the trade. Anyhoo... I'm told that the Ultimate uses a flat 30 ohm resistive load for all amps and then re amps with a SS power amp. At face value that 30 ohm load seems too high. But if you look at speaker impedance curves you'll see that the "load" they're rated at only occupies a very small frequency range in the low mids. All other frequencies being higher. Sometimes MUCH higher. So the nominal impedance of a speaker is really no where near it's rating. It's much higher. This same train of thought was used by other makers of resistive attenuators too. The Kendrick/Trainwreck/Dr.Z Airbrake, for example, uses a 32 ohm load. The idea being that it should still be safe for the host amp and sound more like a speaker at frequencies outside of the rated load. And it seems to work. These attenuators don't blow up amps and players seem to prefere their tone to other models. So...

You could build a simplified version of the Ultimate/Ho type attenuator by using a power resistor for the load and use a voltage divider from that resistor to feed the SS amp. You could even include an EQ in the SS preamp if you like. At that point you'd have, basically, a 30 watt version of the Ultimate/Ho attenuator for a fraction of the cost. The Ultimate/Ho attenuator has been refined for players tastes over the years and has a good rep. That, no doubt, is how they can charge so much money for such a simple concept. It's also worth noting that the Ultimate/Ho design is good for amps up to 250 watts!!! So all that capability is wasted on small amp like yours. Also, you intend to use your unit as an amplifier, not just an attenuator. Which should be a simpler design. In fact, if you only want to use the SS amp for boosting volume, you could just use a voltage divider at the SS amp input and let the host amp speaker be the load. So this raises an important question about your goal with this project. Do you plan to silence the host amp, and then use the SS amp as the only power amp feeding a speaker? This would have the benefit of giving you infinite volume control from whisper quiet up to 30W. Or do you only want the SS amp to be a satellite wattage bump for more power? When your functional goals are clear the design will be too.

EDIT: Part of the point being, there is no sense in using something like the Ultimate/Ho attenuator, capable of 250W, to pad your little amp down to preamp levels to feed a 30W SS amp!?! Why not just use something lika 22ohm/50 watt load resistor as the host amp load, then voltage divide an input level signal from the load resistor, then feed one stage of SS preamp, then a volume control and simple EQ, then to another SS preamp stage that feeds the SS power amp. Then you could plug any amps speaker output, up to fifty watts, directly into your unit and use your unit to attenuate or amplify the signal up to 30W. The divider off the load resistor would need to be made variable so that you can adjust the feed signal for amps of different wattages. And you'll have the benefit of added EQ! Easy peezy lemon squeezy. A $20 panel meter could be added to tell you when the divided signal is optimal for your SS amp making adjustment a simple visual thing. Also include protection diodes to avoid damage to the SS amp input in case the adjustment is wrong for the host amp in use. But the host amp, as long as it's plugged into your unit, will always be safe because it's hooked directly to the load no matter what. Now THIS would be a truely useful gear tool.

Something like this:

[Austin]

You can hook up that 32 ohm speaker to the blackstar amp, it won't hurt it. You could take the signal for the ss amp directly off the speaker leads instead of a resistor too. 1 watt into 32 ohms = about 5 volts swing, 1 watt into 8 ohms = about 2 volts

Ohm's Law Calculations With Power


But I think this idea is lame and that you should just build a tube amp because they are easy and fun and sound nice. You can do it, it is very easy. Don't even buy some expensive kit, just buy the parts yourself and put it together. One single el84 or a 6v6 capacitor coupled to a single 12ax7 with both sides in cascade. You don't even need a volume knob. Less than 100 bucks in parts.

[Chuck H]

But I think this idea is lame

Well... Don't hold back!

...you should just build a tube amp because they are easy and fun and sound nice. You can do it, it is very easy. Don't even buy some expensive kit, just buy the parts yourself and put it together. One single el84 or a 6v6 capacitor coupled to a single 12ax7 with both sides in cascade. You don't even need a volume knob. Less than 100 bucks in parts.

Except that he already has a low watt amp now!!! Your proposal won't get him to 30W as intended. And if you can build even the most bare bones 30W tube amp, domestically, for under $100 your better at this than I am!

Chassis - $30
Tubes - $50
OT - $30
PT - $50
knobs, pots, jacks, switches, filters, pilot, lead wire, components, board and eyelets, misc. screws and other hardware, possible cosmetic appointments and rubber feet!!! Probably another $50 easy! And no one can buy this stuff in town anymore. It's all on line shopping. So there's going to be at least $40 in shipping charges!

We're up to $250 on a conservative guestimate. I'll bet it actually can't be done for less $300. Unless you pay your workers with a bag of rice and a fish head. And low ball everything to death until the amp needs to be re engineered to keep it from failing with such low spec and quality parts.

Just sayin'

[tonequester]

tonequester here.



Hey Austin ! Thanks for the reply to my post. You're idea on building an amp from parts is a definite for me in the time frame of no more than a year, tops. I've had some experience with repairs and mods with tubes, but never a build from scratch. Perhaps I lack confidence or am overly cautious, but at the same time, this first time, I want to minimize the chance of getting something wrong and not being to have a usable amp in the very near future. The MOD 102 kit is only $250.00, and I should end up with a usable amp relatively fast. The on-line support feature may well be needed in my first attempt. You gents here on the forum ALL seem to have much more in-depth knowlege and experience than I do. because of about three months of participation, I feel that I'm much better prepared than I was when I first posted. I have you and a dozen more like you to thank for the increase. However, I'm not as "quick" as I used to be. Often, I don't "see the light of day" until several of you explain something in detail, from several angles. Other times I get what is being explained pretty quick, only to have it completely change my directiion. I'm pretty good at cutting back other areas of my life in order to save what I need tto do a project. I just have the need not to waste what I spend on a given project .I guess I have to "hedge my bets". With good folks like you helping me out, I'll get there. I will say that I now know what it feels like to be "remedial" at something.
Thanks so much for your advice. Every reply you make to one of my posts(the other "guys" also) I now print off for further scrutiny. I started out with a folder. I think I'll end up with an encyclopedia. Have a great one Austin 1 tonequester.

[tonequester]

tonequester here.


Greetings Chuck ! Easy, peezy, lemon, squeezy ! That's just what the doctor ordered for "a tinker, a tailor, and a so-so man" like me. Between you and my friend Austin
I have everything that I need in the mentoring department. Unbridled enthusiasm, reasonable approach, knowlege and experience. I printed off this whole post for consideration. It's made me think and rethink already, and as you pointed out ; What do I want, is the biggest question I can ask. As usual your thumbnail was excellent. I believe that this is exactly what I was trying to form in that great void that IS my mind. The load resistor would be easily incorporated in the inexpensive s.s. power amp(kit). The idea of using a panel meter for adjustment of the input signal is great ! A few bucks worth of protection diodes is a must. Your diagrams are worthy of a textbook. I don't see anything more to consider, other than figuring out the values needed, and ordering the s.s. kit. As for the tube amp kit(MOD 102), It's always been a project to stand on it's own. The $250.00 seems very reasonable for a beginner build. I don't expect a" wall of sound" from it. It should be about twice as loud as the HT-1R, and it will be all tube. I don't expect it to be in need of re-engineering and failure from low spec or parts quality issues. It should serve it's purpose. That being an introduction to the building of tube amps. If I do alright on it, then it's time to "gear-up" to build my best take on an all-purpose amp
with plenty of guts, usable for most occasions. Thanks for correcting me on the Ultimate Attenuator. I couldn't remember "Attenuator" to save my soul as I typed the post. I'm glad to know of your experience with it, and the prospect of approximating it's performance. If I were swimming in cash, I wouldn't pay 500.00 for the thing, but buying the critical parts to approximate it's performance is another thing. Silencing the host amp has been my take on this experiment. I felt that the whole volume thing, as you so eloquently put it : "This would have the benefit of giving you infinite volume control from whisper quiet up to 30 W"., was best addressed by s.s. My only requirements here are : the output consideration(app. 30 W.), and clean colorless amplification
of the input. It's not hard to find a number of kits that will fit this bill. I've done plenty of s.s. projects, so a kit is just an easy and inexpensive way to an end result here. I don't believe I could build one of the s.s. amps that I've been looking at from parts, for anywhere near the kit price. I can get a kit using a well known I.C., F.E.T.s, Mosfets, or Darlington transistors for
well under $75.00, depending on the extras and the power supply needs. Probably the only truly irritating thing about them, is that none seem to come with a power supply, most don't offer one as a seperate kit, and some of the ones that are required are hard to find. Thanks for putting this whole thing in a better light for me, not to mention pretty much how to go about doing it. I just got a box from Stew-Mac(5-way sw.,volume and tone controls), this week I order the pick-ups. By the end of next week I should have finished upgrading my Kramer. That being done, it will be time to tackle this experiment, especially as I now have my Blackstar back(un-attached speaker included). In 2-3 weeks I should have my s.s. power amp kit. I'm leaning to one based on the LM1875 monolithic I.C. It's proported to be 30W. music power, and 20W. RMS, into 8 Ohms. It's considered a beginner's build, so it should go together quickly, even with the modifications that you suggested. I'll be checking into load resistors, a proper panel meter, and perhaps another cheap kit....a "drop in" equalization module. I've seen a couple of simple
bass, midrange, treble controls in module form for around $8.00 to $10.00 bucks. There might be some that are more sophisticated that I haven't taken notice of. Despite wanting no coloration from the s.s. amp, some means of compensation seems only sensible. One can always leave the settings for flat response. Good enough for me. Lemon squezzy ! I'd never guessed
that a man with the true talent befitting a died in the wool Yanker, would be so quotable as well ! I think that this kind of thing comes fairly easy for you, whatever time that you've put into thinking about my mad schemes, I appriciate it, no end. Here's wishing you all the best. Long may you reign as the "Head Yanker" of the forum ! Sincerely, tonequester.

[J M Fahey]

Just curious, what is the DC resistance of that Eminence speaker?.
Also post the resistance shown in the multimeter screen when you join red and black test probes.
Thanks.

[tonequester]

tonequester here.


Hi JM. I just got your post and had a meter handy. The meter is NOT a True Rms meter, but I"m guessing that this won't be a problem. The speaker checks out at 26.8 Ohms. When probe to probe, the reading is .2 Ohms. The meter used always shows .2 Ohms when checked lkie this. I hope this is useful to you. Thanks for the reply, and interest. tonequester.

[J M Fahey]

Thanks.
Just checking that the speaker was *really* 32 ohms .
Many Manufacturers use a general purpose label and hand write with Sharpie or something data such as impedance, power, serial number or date, so it *might* have been a mistake, but you just confirmed it.
Weird.
What was that speaker originally used for?
I'm intrigued because I actually make speakers, and from experience know that 32 ohm coils mean real thin wire, *very* hard to wind, or car audio type 4 layer coils, which I dislike.

[tonequester]

tonequester here.

Good day JM. The speaker is about 30 years old. When I first started to "experiment " with electronics I was pumped up because I had taken a chance on a Fender Princeton
(circa 1960), I was actually trying to get a deal on a Vox AC30, but they were all out of my price range. The guy offered me the Princeton for like $250.00. When he tried to demo it for me, all it did was buzz. He immediately offered me $50.00 as is. I took the chance, and got lucky. There was an intermittently bad groungd to chassis which I fixed. I got the "bug". I started to
scrounge for anything electronic to salvage. A friend had an old amp that was shot, all rusted up, with insulation rotted on all the wires. I scrapped what I could from it and got that speaker.
I couldn't read any specs on it, but checked the D.C. resistance and found it to be 32 Ohms. It was of course not stock for the amp, a Peavy I think. I put it in my junk pile and forgot about it untill I stumbled upon it not long ago. Back when I salvaged it, I didn't realize that it was a little uncommon, but nonetheless figured it would come in handy some day. I was surprised to find that it is still made after all this time. It is an Eminence, model mm-55-220, and if I remember correctly, it is rated at 100 W. Now you know everything that I know about it. I don't know if you caught my post about how I had to repair a thumb size hole in the cone. I found a method of doing so on the internet, and decided to give it a try. I used alternating laminates of soft paper towels, and regular paper, with a flexible fabric glue in between laminates. I did a laminate per day uintil I had 6 layers, and then spray painted it black,carefully avoiding the logo. Darned if it doesn't play fine, and I put some serious volume through it. I had never considered a re-cone. I just figured it would cost me more than the odd-ball was worth to me.
Austin replied to the post after I had patched it. He claims that Eminence will re-cone it "cheap". I haven't checked into this, yet. I still wonder at it's value to me. The thing weighs in at over 5lbs. That's the whole Shee-bang ! Have a great day JM. tonequester.

[J M Fahey]

Googled a little and found this, explaining the 32 ohm speakers.
Replacing the Suitcase Speakers
I bet the original speaker in your amp died and the salesman must have thought "hey !! a 12" speaker is a 12" speaker" and replaced it with some old pullout he had lying around.
Just your luck that it happened to be a weird 32 ohm one.
Maybe it pays to sell it for good $$$ to the Rhodes guys and/or exchange it for a couple "normal" 8 ohm guitar Eminences.
Win-win situation.

[tonequester]

tonequester here.


Thanks JM. At least I have some idea of what probably happened. I appreciate your time in checking this out. I believe that I'll contact the Rhoads guys to see what kind of deal they might be willing to make. Even if they would only swap for one 8 Ohm, 12" it would leave me better off than I am with this odd-ball. As it is, nobody else would be interested in the speaker if just for the fact that I patched the cone. However, the article said that the voice coil is no longer made, so I must have misunderstood the info I found leading me to think the speaker is still made. Perhaps Rhoads guys will be interested. Thanks again for clearing up the "mystery". I probably have several other odd-ball items electronic that could, considering their age, be of some value to somebody. I guess that I'm just a rat-packer at heart. Have yourself a great day. tonequester.

[tonequester]

tonequester here.


Greetings, and thanks to everybody who has replied to this post. The info has been very useful, all around ! I'm trying to determine the voltage output of my HT-1R,
Blackstar. It's one Watt RMS output. If I understand this correctly, The square root of(1W. X 8 Ohms load) would give me...2.828 V. I take it that this would be an RMS voltage. I intend to use a W. x 30 Ohm load resistor to "feed" a s.s. power amp. A potentiometer will be placed after the power resistor for adjustment of signal level, with a panel meter to be able to actually see what's going on,relating signal strength to perceived.In selecting a pot would it be best to use peak voltage instead of RMS ? Chuck H wasgood enough to come up with this circuit for me and has first hjand experience with the Ultimatate Attenuator. This circuit is a sort of no frills version of the expensive attenuator. The s.s. amps input sensitivity is 100mv. @
4.7 Khz. just for the record. The s.s. amp is in kit form, and inexpensive. The kit does not give any specs related to max. input signal. It's input impedance is 150kOhms.
Any tips or opinions are welcome. Thanks for all of the help already given here.

[überfuzz]

If we cut to the chase, it seems you're looking for an economy class amplifier to build. Scavenge the local craigs list and see if you can find one or two amplifiers in non working order. This way you'll have more then enough to tinker with and you'll probably end up with something nice.

[tonequester]

tonequester here.



Greetings uberfuzz. Thanks for the reply. I hadn't even given Craig's list a thought in this matter. One never knows 'til they try. I'll check it out to be sure.
I'ts nice to make your aquaintance of the forum. Thanks for the tip and have a great day ! tonequester.

[überfuzz]

Greetings uberfuzz. Thanks for the reply. I hadn't even given Craig's list a thought in this matter. One never knows 'til they try. I'll check it out to be sure.
I'ts nice to make your aquaintance of the forum. Thanks for the tip and have a great day ! tonequester.

Well, you probably have your priorities sorted. I always keep an eye out for amplifiers with an owner that has given up on them. But on the other hand, a kit is a sure way to get everything needed in one blow. Good luck with your first build!

[tonequester]

tonequester here,


Greetings Chuck. I hope that all will excuse me if this isn't a proper way to post. This concerns what has been bantered about on this topic. I have found out how to receive personal messages on the forum, but as yet, have not figured out how to send one. Anyway, I have found the s.s. kit amp that I am going to build. Thanks to loudthud, I will be ordering a Velleman kit, model-K8060,Discrete power amp, 200W. Loudthud has taken the time to "tweak" the circuit, with a ct transformer rated A.C. to 36v.a.c., 100VA. The circuit is based on Epitaxial Darlington transistors. The 200W. is misleading. That's "music power"@4 Ohms. It's 100W. RMS@4 Ohms. I will be using 8 Ohm speakers. By the time I buy the kit, the transformer ,the heat-sink(more expensive than the kit), and what is needed for a decent enclosure, I'll be going over the $100.00 mark easily. However, it should be very robust, and suit my needs. I am still going to utilize the attenuation circuit with panel meter that Chuck H has been good enough to outline for me. The first part of this circuit is a load resistor(power type)
which Chuck suggested in value as being 22 Ohms/50W. I am wondering about the 50 W. value. i have finally received my HT-1R from the shop(brand new), and this time they saw fit to provide me with a proper manual. I now know that it's 1 W. output is RMS. So I guess my first question is, would one need the load resistor to be rated as high as 50 W. Please,pardon my ignorance in this. I have never done this complex a project(for me). I also wonder if/how the s.s. amps own input impedance figures into this. I ASSUME it doesn't. I think that I am right in thinking that a decent panel meter would not constitute a load worth worrying about. I have always wanted to take the output of the HT-1R directly from the speaker output. One reason for this is that the speaker out jack on the back of the tube amp is rated 4-16 Ohms. It seems to me that there must be considerable difference in that output and the signal from the speaker wires. If anyone has any opinions on my ponderings, as I get the cash together to begin, I would appreciate hearing them. The attenuation circuit is basically tube amp input to load resistor,
then governed by a potentiometer, through the panel meter, through a diode protection circuit, and finally into the s.s. amps first stage. Thanks to loudthud, and Chuck H, as well as many others who have given me advice concerning this project. Best Wishes to Everybody !!! tonequester. P.S. The thumbnail of Chuck H's attenuation circuit can be found in this collection of post and replies under Chuck H-"I think your talking about the Ultimate...".

[Chuck H]

Ok.... That amp is only a power amp. So any volume control must happen to the signal your putting into it. That is, there is no pre amp for processing like EQ and volume. Now...

Of course you don't need a 50W resistor for your little amp. But, is this project ALWAYS going to be exclusive to your 1W amp??? The resistor rating assumes not. My idea was that you could plug the speaker output from almost ANY amp into your new project and then use it as either an amplifier OR an attenuator. In other words, you could plug in your HT-1R and make your HT-1R a 70W amp OR plug in a 50W amp and make it a 1W amp if you wished. In light of the "discrete" nature of the amp your going to build, you could take another route. Build the power amp as planned, but also build an interface box. As it happens, panel meters operate on wattage. And the input to your power amp is only dependent on voltage. Setting up a meter to detect voltages in the mV range would require another amplifier. Albiet a simple one. But it complicates the project. So the interface box might be an easier, less expensive and in light of the amp your going to build, more versitile. You could run the interface into effects or EQ's and such as well as feed any other device besides your new power amp. I think this could be a very useful tube amp tool for a tinkering musician.

The "clip indicator" isn't really a clip indicator, but rather an indication of when the amount of signal leaving the interface is likely to clip the input of another device. So you would adjust "voltage divider 1" by turning up the sensitivity until the clip indicator blinks and then back down the sensitivity little. After that the volume control (which is another voltage divider) can manage the signal strength appropriately from zero signal up to the selected output (line or low). The protection circuit would be set up to clip any voltage above about 2VAC for 'line level' and 500mVAC for 'low level. Obviously this will still allow you to clip the input of a following device. But it will abate gross mistakes.

I could even work up a schem with circuits and values if you like. I actually have fun with that sort of thing. The parts should be very affordable.

[tonequester]

tonequester here.


Hi Chuck ! I was in no doubt that the 50W. resistor was needed. I would have sent you a personal message, but I haven't figured that out yet, here on the forum. I just found out that I had some personal messages. I hope that it wasn't a problem to post this way. I'll figure out the personal message thing a.s.a.p. I was short sited on the resistors value.
I had not given thought to the possibilities, but I get it now and it is a great idea. The interface box block diagram makes good sense. I'd be very willing to send you $20.00 for your design.
Your time is worth it and more. I can see that the circuit wouldn't have to be expensive. I do plan to build a "life-time amp" at some time, after I do the simple MOD 102 kit build. I figure that if I do a good job on that, I might even be able to sell it off and put the money towards a more complicated build. I'm kind of into "one step at a time" these days, and I always have to consider saving up the cash for what I will eventually wish to build. If the s.s. thing works out as I hope, it might well be a part of the picture with my "life-time" build. If you don't want the twenty, you could donate it to the forum.....always a good investment. This "project" has taken on a life of it's own. This has happened to me before. What I don't lack in imagination, I do in knowlege. You and a few others have been quite good to me and my schemes on this forum in sharing what you know. I print off all of your replies and thumbnails for reference and study.
I would be a lot easier to work with if I wasn't so new to the whole computing thing. I hope to catch onto the forums "extras" in time, and get myself set up to be able to share photos of
the projects that I complete with the help of the forum. My last order for the upgrade/modification of my guitar is in. The next project is the s.s.amp and the interface box. Please take your own time in designing your circuit. Time is one thing(God willing) that I DO have. For the average performing guitarist, the "clip indicator" could be a real winner. Most of the player's I've met over the years have less on the ball electronics wise than I do. That's one of the main reasons that I got into it to begin with, and continue to make the attempt to learn more. You, loudthud, JM, and some others have made that much easier than it was before I joined this forum. If you are not a design engineer, or an electronics teacher of some sort, you should be. Maybe you were, or are. Chuck H works for me. Give me a holler when you wish, by whatever means, I always get the message. Well, you know what I mean. I believe that this project is SET ! It ain't built yet, but I will say that assembly is one area where I am at my best. They actually used to pay me to do some of that. I wish I'd had you there to tell me just exactly
why and what I was assembling. Thanks for all of your ideas, advice, and those excellent block diagrams. My best wishes for you. sincerely tonequester.

[Chuck H]

Most of the player's I've met over the years have less on the ball electronics wise than I do. That's one of the main reasons that I got into it to begin with, and continue to make the attempt to learn more.

That's one of the failings of being an amp designer. You REALLY need to dumb down the function, operation and intuition needed to operate the amp. We have posters here that have built a few amps already, have a basic knowledge of electronics, and still don't understand why their BF clone farts out with the bass above 2 when they overdrive the amp?!? BECAUSE THERE'S TOO MUCH BASS. If you turn the bass down you can still get the same bottom end in the final EQ because too much bass just clips off and sounds flabby. Because the amps I build are basically vintage style "hot rods" all souped up to get high gain when needed I have, on more than one occasion, had to explain their operation to people that are use to channel switcher types. For example, with a vintage style amp that is clipping hard the EQ controls cease to be EQ controls. They begin to act more like distortion character controls. This is because any adjustment they make to the wave form is lost because these controls are ahead of some clipping stages. Any final EQ balance in a vintage style amp is a matter of the cabinet, the speaker, the OT, what type of power tubes are used and their operating conditions, etc. The "tone controls" do almost nothing to the amps final frequency balance once the amp is clipping hard. But, believe it or not, A LOT of otherwise knowledgeable people don't get this concept. Non tech players that never used vintage amps are utterly confused by it.

This has been the lynch pin in marketing my designs. What use to be common knowledge, understood or not, for amp operation is now specialized knowledge that modern players don't want to bother with. It's much easier to buy a digital sampling amp that will give you 90% of the tone, more versitility, easier operation and one third the cost!!! Hell, I practically talked myself into one just now! But I gotta have that last 10%. When people who've bought my amps first heard them they felt the same way. I just hope the crazy cranks in the world, like you, me and the other posters here, can keep enough of a niche going that the ideals don't fade away. I do see positive things in the market. Kids and noobs line up to buy cheap Chinese made tube amps (that actually sound really good most of the time). Sad to see the industry leave our shores. But that's our own fault, and another story. But it does speak about the sensibilities of the new players. That they would still often choose tube amps.

No, I'm not a designer outside of those designs I make for myself and the odd custom order. When I say odd I mean it. I don't build professionally and have sold less than a dozen amps that cost more than average and I never made a dime. I did do a little design work with one big cootie in the industry and even presented one year at NAMM. Those doors are still open but I'm not involved in current projects. So I'm just a guy that likes the way amps sound and is always trying to learn why they sound like they do and how to make them sound the way I want them too.

[Steve Conner]

Chuck, that is absolutely true , I think the way to design a vintage amp is to choose the speaker, cabinet, tubes, OT and so on for the tone you want, and then just have a volume control and nothing else, like the Brian May AC30.

I appreciate you taking the time to help tonequester out, however given the budget constraints, I'd have to question the need for an expensive panel meter in the attenuator? The output is going straight to a solid-state power amp with no gain control, so the attenuator's output control is effectively the master volume, and you can set it by ear.

If I was looking for some kind of metering, it would be a clip indicator for the SS power amp, but I'd probably end up ignoring it too. I found that I could clip the SS power amp quite a bit in a setup like this with no major bad effect on the tone.

[J M Fahey]

Hi tonequester.
Just checked your Velleman kit.
EXCELLENT choice.
Why do I say so with capital letters? ...
Because I know it very well, it's basically the same as my own 100W power amp, which I have been using successfully for over 40 years now (first with 2N3055 outputs, then switched to TIPs) and know very well what it can and cannot do.
1) it's really 100W/4 ohms or 70/8 as they say.
2) use a transformer of *maximum* 30+30VAC .
If you go a little lower, so much the better. (say 28+28 or 27+27)
You still have more power than you need anyway, and it's safer.
"Old time" transistors were always built over spec, competition was based on quality.
Today competition is cut throat based on price, amd even the "good" brands (ON, ST, Fairchild) which I use now meet the specs and just that.
Up to 10 years ago I run these transistors with beefy +/- 45V rails with no problems at all and they were 90W into 8 ... then had to lower to +/-42 ... +/-40 ... now I'm running about +/-38 or 39 .
Anyway, you will have the power of a moden Bandit, a Marshall/Laney/Crate "80W" SS amp, you can play anywhere along any drummer, which is the real yardstick to mneasure performance.
Now you ust need to sell that speaker to a Rhodes fan, buy a new car and with the spare money buy a new peaker

[Chuck H]

+1 on nixing the panel meter. The one I used on my last project (that used one) was a real cheapy ($22). But it was set up to detect wattage, not voltage. A meter for that would be MUCH more expensive OR another small amp would need to be designed just to run the meter. Either way it's overkill for this project. The only reeason I thought it would be a good idea is that it would instantly identify the useful level whether using a 1W amp or a 50W amp. 'cause there's A LOT of variable there. But I like the new idea better anyway. and it uses a simple LED. The "protection circuit" will keep any user from putting 20VAC into an amp input and I expect the resulting sound should be indication enough without blowing anything up. That, and the LED lighting up.

[tonequester]

tonequester here.

G'day Chuck ! I guess that were both a little odd-ball. However, given that we are so about THIS subject, I believe that a little thought outside the box is appropriate.
My experience with the musicians I've know over the years is that they are much more in the know concerning their musicianship, than with their own equipment. Presently, I'm lucky enough to know a few that readily admit this. I'm not nearly as knowlegeable as I would like to be, and admit that. However, I do my best to learn about even their equipment. I've known those that didn't care to know anything about their amp besides how much power it had(no concept even of RMS or "music power"), and where the volume control was. They were also usually not too concerned whether they were in tune or not. I fully understand your 10%. It's the same thing that I have always sought. I have been lucky enough to here my share of vintage amps, when they weren't even called vintage. I've also heard the Line 6's of the world, which claim to have captured the 10%, but don't deliver(to these ears). This project has come a long way since the first post. I've got 20+ pages printed off, and another 6 hand-written. I believe I will continue to do this until the amp is built. The title : The Evolution of a
Novel Approach to Electric Guitar Amplification. I feel that everybody who has contributed with their replies has done me a great service, which I can only hope to re-pay. Whether it's music, or electronic's, often the "odd-ball" has been the one who has made the difference between success and failure. I'm on the same page as you are, even if I'm not yet up to your level of expertise. you have made that possible with your ability to explain that which is not easy to explain, nor always easy to understand. You and several others on the forum are odd only in
their passion for music/electronic's. It's not everybody's "cup of tea". I drink it by the gallons ! I believe that you do as well ! I am sure glad that you are here where you belong, for the wanna be's like me to benefit. Have a great day Chuck. tonequester.

[tonequester]

tonequester here.


Greetings Steve. thanks for the reply to the post. Also, it's good of you to be mindful of my budget constraints. At times, I get so into a project that I forget them.
I hadn't gotten around to seeking a panel meter, so have no idea about their cost. Chuck H is in agreement with you and I see no problem with some type of indicator light/L.E.D..
I must also admit that in principle, i am in agreement with your thoughts about just how an amp should be designed. I've shunned the normal passive tone controls on guitar and amps alike almost from the start. Perhaps an odd reason for this is that I just don't like subtracting from the signal in that manner. it's just one of those gut things, I guess. I was willing to try something different, that "sounded" like it might ADD something to the end sound(Q-filter). After doing a little study on your opinion of that particular "circuit', I now realize that it's just
the same old tweeking by subtraction. One less switch, one less knob to fool with while you try to play. The idea of designing for tone instead of altering what you have created, whatever you have created seems pretty sensible to me. One thing that I will admit to being fond of with regards to adjustment on the fly, is the change, mid-solo, of pick-ups for tonal effect.
I've always admired Leslie West for doing this fairly often, and I try to emulate him in this regard, typically the shift from bridge to neck. Best wishes to you and your projects. Thanks for your continued interest and replies. tonequester.

[tonequester]

tonequester here.


Greetings JM. I'm happy to know that your opinion of the kit is a good one, and based on personal experience, as well as your over-all knowlege of the subject.
I am printing off your reply as well to add to my documentation of the evolving project. Your perception about being able to "hang' with a drummer is indisputable, and nothing quite ruins a
song like a domineering drummer, whatever the root cause. It's a relief to know that I won't have to worry about being underpowered, even in the future. I'm e-mailing "Rhoads" about the
"vintage" speaker and if I can get enough to buy the heat-sink for the power amp I'll be happy. The new car can wait. after-all, I have an amp to build. remembering the old Camel commercials, to paraphrase......I'd walk a Hell of a lot farther than a mile for my tone. Great hearing from you on this. Best wishes" Argentina Way". tonequester.

[tonequester]

tonequester here.


Chuck, as for me... I am always sure to turn volume completely down, before plugging in. I even check the polarity of unfamiliar outlets. I don't even fire that HT-1R up without checking it all out. My first amp, the Princeton, did not have a stand-by switch, and I quickly learned to hate that" pop"when turning on with the volkume up. I do like the protection circuit idea, and I am one to pay attention to L.E.D.'s being lit or not. It seems that all opinions are that the direction of the evolution of the project is proceeding well.
I have to give credit here to loudthud, for his nixing of my last choice of kit, and his subsequent choice of the Velleman kit. he pointed to a lack of "robustness' in my last choice, and felt that this Velleman would be very reliabile. It's hard to fail when one has as much help as I've had on this forum. thanks to all ! tonequester.

[tonequester]

tonequester here.



Greetings JM. I have a few questions/thoughts concerning the K8060 kit/amp if you should get the time. With your personal eus and experience with this type of amp
I feel you would give me the best info coincerning said amp. I've been studying the data sheets that I've downloaded for all semi-conductors used. I must admit that I have Zero experience with the Darlington "pair". So I'm trying to get up to speed on it's basic functions, advantages , and disadvantages(if any). I had to look up the definition of epitaxial just to get started.
I ran across a review of the kit, it's assembly, and it's performance entitled : A very good home-made velleman K8060 discrete power amplifier(2 X 100 W rms) and a stereo set-up. This
article @www.spannare.se/k8060.html. Over-all I think it was a very positive review. I know that it is not the exact same application as what iIintend for my amp, but bear with me and my lack of knowlege. He(author) recommends the mnodification of using 4700uf filkter capacitors, instead of the stock 3300uf caps. Did you do this on your build ? He also claims that a 10 k
log pot is better than the 47 k log pot shown in the manual. What is your opinion of this. There is also mention made that a separate RCA switch is necessary for many signal sources.
Would this apply to my situation, inputting low power tube amp,via "attenuator adaptor" to the box. This perhaps would be best addressed with the output connection design of the
"attenuator". I'm basically getting together a list of "accessory parts" for the kit, and wish to be able to start "shopping around" for them. His main concern with the build itself, seemed to be the care that must be taken and the time involved installing the heat-sink.

[J M Fahey]

Study for your own improvement but the beauty of a (well designed) kit is that you build it and it delivers what's promised so you can do it now instead of 2 years in the future .
Velleman is a serious company and their instructions are excellent.
Consider them for other things you may need in the future.
Start thinking about what cabinet or chassis you will fit this kit into, so you can transport it to a Club or rehearsal studio.
Generally the "mechanical" side is the most complex for the home builder.
*Maybe* you have a sheet metal shop nearby which can build a simple chassis, or explore the ones offered by Hammond Industries or other suppliers.
Or, one of my favorite solutions, get a dead guitar combo for free or peanuts (garage sale/Salvation Army/"dumpster shopping") , gut it, ,and you'll have a cabinet, empty chassis with power switch, fuse and power cable and maybe even an OEM guitar speaker.
You turn it into a powered box to boost your small tube amp.
Similar to a Tech 21 Power Engine 60 !!!
Tech 21 Power Engine 60 | Musician's Friend
How's that !!!!!

[tonequester]

Study for your own improvement but the beauty of a (well designed) kit is that you build it and it delivers what's promised so you can do it now instead of 2 years in the future .
Velleman is a serious company and their instructions are excellent.
Consider them for other things you may need in the future.
Start thinking about what cabinet or chassis you will fit this kit into, so you can transport it to a Club or rehearsal studio.
Generally the "mechanical" side is the most complex for the home builder.
*Maybe* you have a sheet metal shop nearby which can build a simple chassis, or explore the ones offered by Hammond Industries or other suppliers.
Or, one of my favorite solutions, get a dead guitar combo for free or peanuts (garage sale/Salvation Army/"dumpster shopping") , gut it, ,and you'll have a cabinet, empty chassis with power switch, fuse and power cable and maybe even an OEM guitar speaker.
You turn it into a powered box to boost your small tube amp.
Similar to a Tech 21 Power Engine 60 !!!
Tech 21 Power Engine 60 | Musician's Friend
How's that !!!!!

"Lead from the front !" Audie Murphy.

Greetings JM. You make a good point, as usual. If the people who designed and produced this kit didn't know what they were doing, they might be sacking groceries for
$6.00 ab hour. I will build as instructed, However I am reminded of the power supply considerations that you related to me, and the quality of todays semi-conductors when compared to those of the past. I think that it might be a good thing to go a little conservative on the supply voltage, if that could be a worry. Please correct me if I got this wrong. I am considering this projects use in the future. it did not begin this way, but you gave me cause to pause and think on this. This is why I am trying not to "go cheap" as a first priority. I appreciate your advice and keeping me grounded in common sense, which I all to often leave out of the equation. I haven't any knowlege of the Tech 21 Power Engine 60, but will check out your lead. Thanks much for the reply. It just occured to me that this has become a truly international project. I have had good advice from : Argentina, Scotland, England, Russia, and all over the U.S. funny how well simple folks like us can cooperate so well, and our leaders have such a time of it !
Have a great day in Buenos Aires ! tonequester.

[tonequester]

tinequester here.


Jm. I just checked out the Tech 21 Power Engine 60 at Musician's Friend. If this project does nor "pan out' this looks like a good alternative. Just considering the price
it seems like a good investment, when most s.s. state 60W. amps are higher. It al least sounds like connecting my Blackstar would not be a problem. I'm glad to have a back up plan in any case. thanks again for a good tip. tonequester.

[J M Fahey]

Yes,it's a clever idea.
An amp designed from the ground up, not to be used by itself (although it can, in a pinch) but to boost others or an emulator (Pod, VAmp, etc.)

[tonequester]

tonequester here.


Hey JM, Yea it's clever alright, and it's pretty much what I was "looking for". If the kit doesn,t do the job as expected, I'll turn it into the amplifier for a new stereo somehow, and go for the Tech 21 to "power-up" my little tube amp. $300.00 for the tube amp, and $399.00 for the Tech 21 would not be really "out of line" for the cost of a 60W.,
tube amp, and I already have very good tone with the little HT-1R. Thanks for the reply and have a great day JM ! tonequester.