First tube amp build: Fender Deluxe AB763 style amp (no reverb).

[mikepukmel]

I use contact cement and any brand name HD aluminum foil. I don't know if there's a better way, but I figure the contact cement is less likely to go brittle and drop foil on the circuit and the known brand HD aluminum foil is just noticeably heavier than generic On one project I stapled aluminum flashing. Traynor did that with a thin sheet of steel. I didn't like it. Too many edges with the thicker sheet material and staple ends that can make chassis removal and installation persnickety. That, and I worry a staple could loosen and drop into the circuit or that the sheet could develop a vibration rattle. So I'm back to contact cement and HD foil.

Thanks Chuck. The reason I didn't do anything so far, was that ssoooo many period fender amps ive seen, someone got angry trying to remove the chassis, and used a screwdriver to try to get the lip past the cardboard/foil thingthey had in there, and dented the heck out of the faceplate and or chassis. I even remember a guy doing that back in high school "IIIII can fix it .... " probably the same guy who put aluminum foil over the burned fuses. .. I willtry the glue/thick foil method. I think my wife gets this really thick aluminum foil for some special use, soemthing like freezer foil. I was very surprised how thick it was. If thicker is needed could get a thin, thin plate from like Online Metals, but shipping is a fortune for that little stuff. Did you have to run a wire from teh foil, or was it good enough to just be in contact with the lip on the chassis someplace?

[mikepukmel]

A friend of mine has a MB Mark III head and the matching "half open back" Mesa cabinet, meaning bottom half closed back, top half closed or open back courtesy of a removable back.
Top houses 2 visible "Black Shadow by Celestion" and sounds killer, bright and punchy ... like a Celestion should

Bottom half is supposed to hold 2 Black Shadow EV´s , which of course are invisible.

I had my doubts, because: cones looked generic conical multi ribbed guitar types, not the distinctive curvilinear/exponential/"trumpet bell" EV ones, the cabinet was heavy but not more than a conventional Marshall 4 x 12" (EVs are **heavy**) and to boot cabinet was loud, fat and punchy, but did not show the pants flapping EV bass.

Of course one day "just by chance" I had a Philips screwdriver in my pocket and opened it up: it housed 2 **unlabelled** (not even Black Shadow or Mesa) black stamped frame (not cast aluminum) speakers, 150mm diameter magnets (not 190mm double thickness EV) plus the back plate had the telltale 6mm "Eminence hole" , the one they use to hang the back plate in the cataphoretic black paint tank.

Didn´t have the narrow Eminence barcode label glued to the magnet side (easy to remove if needed) but everything else screamed EMINENCE!!! .

Not a bad speaker at all ... just that my friend payed extra for the "EV loaded" one

FWIW I didn´t tell him ... he loves his amp which by the way has a killer sound, it´s an intermediate model between the original "Blackface amps with gain" and latest Metal meat grinders and he pulls a very nice Power Blues sound out of it, so who am I to rain on his parade?

Thanks for the note, Juan, great to hear the black shaodows sound good. Really sad to hear your friend didn't get what they paid for, re the bottom half speakers. Wow, I thought that mesa had better business practics than that. The more I hear about mesas the more Id like to try one out someday, regarding tone. is the MK III a good one to look at in general?

[Chuck H]

I just install the cabinet and count on cabinet to foil contact. I never worry about oxide layers. Hasn't been a problem yet.That doesn't mean it can't happen. That IS how they dielectric aluminum capacitors after all. I suppose you could go to the trouble of putting a screw with some anti ox grease into the foil and have that point grounded to the chassis with a little jack of some kind. I wouldn't bother.

[bob p]

As far as shielding goes, there are several ways you can do it.

* metal foil or sheet
* fine mesh metal screen
* foil tape

I've used all of the above. If I use a Hammond chassis I'll pay the extra $12 or so to get the matching sheet metal top and I'll screw it to the chassis rather than attaching it to the cabinet. I think aluminum foil tears too easily, I like something more robust. Fine mesh screen works pretty well. I staple it down and it seems to be more durable than foil. In a pinch, I recently tried using 2" adhesive foil tape, like you'd find in the HVAC section of a hardware store. I laid it down in strips and secured it with staples. It did the job.

In the big scheme of things I'm not sure that the chassis sheet we see on Fender type amps is all that necessary if you execute your build conscientiously. If you use shielded cable on your low level signal connections, proper wiring methods to place snubbing resistors on tube sockets and keep leads short, then you shouldn't have to place a lot of reliance in the RF shield. In some respects it's like putting on suspenders while you're wearing a belt.

[Leo_Gnardo]

Thanks Chuck. The reason I didn't do anything so far, was that ssoooo many period fender amps ive seen, someone got angry trying to remove the chassis, and used a screwdriver to try to get the lip past the cardboard/foil thingthey had in there, and dented the heck out of the faceplate and or chassis. I even remember a guy doing that back in high school "IIIII can fix it .... " probably the same guy who put aluminum foil over the burned fuses. .. I willtry the glue/thick foil method. I think my wife gets this really thick aluminum foil for some special use, soemthing like freezer foil. I was very surprised how thick it was. If thicker is needed could get a thin, thin plate from like Online Metals, but shipping is a fortune for that little stuff. Did you have to run a wire from teh foil, or was it good enough to just be in contact with the lip on the chassis someplace?

I've had the sticky chassis on many occasions. I keep a couple sheets of brass around from a hobby shop, two thicknesses. One's a bit flexible and the other sort of stiff. I can usually slip the thinner one between chassis and aluminum plate or screen and free up the chassis that way. I s'pose you could use a butter knife, pancake flipper, spatula, putty knife or similar.

For Fender type amps, contact between the chassis & shield metal on the box "ceiling" works well enough once the chassis is bolted into place. Not so much for tweed-style boxes, there's often a gap between shield & chassis. For those you can run a grounding wire from chassis to shielding. I generally use a solder tab on the shielding, but it's a challenge to find a screw short enough while also having adequate threads to hold it in place on the back cover.

[mikepukmel]

Thanks leo. Ive had amps over the years, some with the aluminized cardboard (or whatever you call it) and some with what looks like a piece of the screen out of the screen door. As I recall the screen door screen seemed to bunch up and get caught a little easier, but it was an old beat up amp (they all were!) so probably missing whatever it was that attached the edges. Does the type of metal matter, should i use the same stuff that the chassis is made of, steel?

[mikepukmel]

The replacement Hammond PT is on the way!! Got a message from Hammond tech support, due to a glitch my replacement was sent out yesterday (should have been here last week). The extra time gave this newbie tech a chance to go over the wiring two more times. An aside, just read a post on facebook from a guy who really thought he had his build checked out, was convinced everything was solid. Plugged in the rectifier tube, turned the power on, and smoked the first dropping resistor. Said it got "red hot" before he turned it off. So, I will use tonight to go over all of the wiring a 3rd time before putting the tubes in and giving the thing its first live run.

Q: I have a right angle guitar jack. I was going to use it for the speaker wiring, since the "Fender" right angle for speaker jack is like 8.00 and the little plastic cap another 4.00. any problem with using a guitar jack? Are the internal connections for the tip thick enough to handle the speaker current?

[mikepukmel]

Sincere thanks to everyone for all the suggestions and help.

As mentioned in another thread about voltages, got the amp all together last night, last few "did I do this right" checks, powered up, and it sounds awesome, just like a fender! I understand that the speaker has some break in period, so it will mellow a bit, its a little bright now, since the cone surround is still quite stiff.

I started out with the bias set below half way, range is something like -30 to -65 v, I set it at -40 or so before I could measure and do the bias.

I could not get the volume up too much since the Mrs was home and it was late when I got it running, but even over half way, it didn't break up. ? No 'farting out' as well, it really pushed the bass notes and rattled the junk on my shelve with the bass on 10.

The only mod's to the stock circuit are: 1) the soft fail 100v rectifiers on the inputs to the tube rectifier, 2) added 68k grid stops on the second half of the 12ax7 preamp tube, 3) moved the grid stops on the preamp tube right onto the socket pin.

Merlin suggested upping the grid stops if blocking distortion was a problem, but its loud enough at high enough bass that I will probably leave it as is.

My office at home is a tiny room, so it was just over uncomfortably loud at a little over half volume.

Measured B+ voltages are a lot higher than what is on the schematic, which I guess is not out of the norm, given today's wall voltages and all of the tolerances? I'll play it a little more and measure everything again when I do the bias, but if its still in the 460 to 480 range, sounds like I should at least swap the first two filter caps that are 475v rated, with 500's, as NickB mentioned on the other thread.

[mikepukmel]

Sincere thanks to everyone for all the suggestions and help.

As mentioned in another thread about voltages, got the amp all together last night, last few "did I do this right" checks, powered up, and it sounds awesome, just like a fender! I understand that the speaker has some break in period, so it will mellow a bit, its a little bright now, since the cone surround is still quite stiff.

I started out with the bias set below half way, range is something like -30 to -65 v, I set it at -40 or so before I could measure and do the bias.

I could not get the volume up too much since the Mrs was home and it was late when I got it running, but even over half way, it didn't break up. ? No 'farting out' as well, it really pushed the bass notes and rattled the junk on my shelve with the bass on 10.

The only mod's to the stock circuit are: 1) the soft fail 1000v rectifiers on the inputs to the tube rectifier, 2) added 68k grid stops on the second half of the 12ax7 preamp tube, 3) moved the grid stops on the preamp tube right onto the socket pin.

Merlin suggested upping the grid stops if blocking distortion was a problem, but its loud enough at high enough bass that I will probably leave it as is.

My office at home is a tiny room, so it was just over uncomfortably loud at a little over half volume.

Measured B+ voltages are a lot higher than what is on the schematic, which I guess is not out of the norm, given today's wall voltages and all of the tolerances? I'll play it a little more and measure everything again when I do the bias, but if its still in the 460 to 480 range, sounds like I should at least swap the first two filter caps that are 475v rated, with 500's, as NickB mentioned on the other thread.

[eschertron]

After 200+ posts in this thread, I think you owe us some pics and soundclips!

[mikepukmel]

After 200+ posts in this thread, I think you owe us some pics and soundclips!

Most definitely!

[mikepukmel]

After 200+ posts in this thread, I think you owe us some pics and soundclips!

How do people usually record sound/video clips? I don't have a smart phone. My camera takes movies, I think but the sound is pretty crappy. Looking for a microphone, I think I have one someplace that needs an input jack.

An aside: my brother, who is a fine guitarist, came over to check out the amp. He brought his old SG, that has two really nice double coil humbucking pickups (don't know the brand but good for that guitar). With that guitar, the amp sounds a LOT more like I thought this amp should sound, much more punch and good midrange. Sounds really nice! I have a G&L with 3 single coil pickups, sounds very, very bright and not a lot of midrange. Would love to get a couple of sound clips up, even with my terrible playing skills.

[bob p]

How do people usually record sound/video clips? I don't have a smart phone. My camera takes movies, I think but the sound is pretty crappy. Looking for a microphone, I think I have one someplace that needs an input jack.

I prefer not to bother with sound and video clips, for a number of reasons.

First, I have no desire to show off my amps or my playing to strangers on the internet. It means nothing to me. I don't think anyone else is really interested anyway.
Second, I have no interest in hearing what strangers on the internet think about my amps or my playing. The opinion of strangers means nothing to me -- partly because I've been doing this so long that I don't feel the need for most peoples' advice and partly because of Point #5 below.
Third, recording is a time consuming pain in the ass and I don't have that much time to waste on recording. My free time is so limited that I'm not willing to commit a major investment in time just to capture a moment in time for total strangers. I'd rather just play music in the moment, enjoy that moment and let the moment pass... and then repeat.
Fourth, I already have too much gear and I don't need or want a home studio, and all the gear and clutter that goes with it.
Fifth, sound clips say more about the process of recording than the object being recorded. I'm not sure that any recordings that I hear on the internet accurately represent the way an amp would play or feel to me. Someone with talent in the studio can get all sorts of different tones out of an amp, which might not accurately reflect the character of the amp in person. For this reason I don't trust other peoples' clips and I see no point in making my own.

An aside: my brother, who is a fine guitarist, came over to check out the amp. He brought his old SG, that has two really nice double coil humbucking pickups (don't know the brand but good for that guitar). With that guitar, the amp sounds a LOT more like I thought this amp should sound, much more punch and good midrange. Sounds really nice! I have a G&L with 3 single coil pickups, sounds very, very bright and not a lot of midrange. Would love to get a couple of sound clips up, even with my terrible playing skills.

I've found that G&L guitars are very bright, moreso than Fenders. As it came from the factory my Legacy was obnoxiously bright sounding compared to a Strat and I did not like it. I started threads about that here, and there's been a bit of discussion on the subject that included suggestions about modding the tone circuit to get rid of the excess treble. Some people think that Leo's HF hearing loss possibly contributed to the progressively brighter voicing of his guitars through the years.

[mikepukmel]

I prefer not to bother with sound and video clips, for a number of reasons.

First, I have no desire to show off my amps or my playing to strangers on the internet. It means nothing to me. I don't think anyone else is really interested anyway.
Second, I have no interest in hearing what strangers on the internet think about my amps or my playing. The opinion of strangers means nothing to me -- partly because I've been doing this so long that I don't feel the need for most peoples' advice and partly because of Point #5 below.
Third, recording is a time consuming pain in the ass and I don't have that much time to waste on recording. My free time is so limited that I'm not willing to commit a major investment in time just to capture a moment in time for total strangers. I'd rather just play music in the moment, enjoy that moment and let the moment pass... and then repeat.
Fourth, I already have too much gear and I don't need or want a home studio, and all the gear and clutter that goes with it.
Fifth, sound clips say more about the process of recording than the object being recorded. I'm not sure that any recordings that I hear on the internet accurately represent the way an amp would play or feel to me. Someone with talent in the studio can get all sorts of different tones out of an amp, which might not accurately reflect the character of the amp in person. For this reason I don't trust other peoples' clips and I see no point in making my own.


I've found that G&L guitars are very bright, moreso than Fenders. As it came from the factory my Legacy was obnoxiously bright sounding compared to a Strat and I did not like it. I started threads about that here, and there's been a bit of discussion on the subject that included suggestions about modding the tone circuit to get rid of the excess treble. Some people think that Leo's HF hearing loss possibly contributed to the progressively brighter voicing of his guitars through the years.

Got it, Bob, thanks, yeah same here re most points. For a newbie, the only interest I have is in what you experts think the amp sounds like, but, geez, the whole thing depends so much on the mic and mic placement, ... etc. etc.

Re G&L and fixing the tone, ooohh! Cool, I will look up those threads. I would like this guitar to sound more 'like a strat'. its too damn bright. So, short question here, probably wrong place, but ... Did you find the pickups OK, but it was mostly just the tone circuit (pots, caps, etc). Im not against replacing the pickups and tone circuit to tame this guitar down, nice if I didn't have to.

[bob p]

Reading my last post, I know I sounded like an antisocial Grinch. Suffice it to say that I'm confident enough that I know what I like, and that soliciting other peoples' opinions won't particularly help me. In your case, all of our opinions don't really matter that much as long as your amp build sounds good to you, and maybe to the other people who get to actually play through it. Of course that situation changes completely if you're trying to build an amp for sale to other people. Then you have to bow to the will of the masses.