Looking for advice, if you please.

[tonequester]

Tonequester here. I have some electronics background, and sometimes I think that it's just enough to put me in the "smoke and fire business". So any feedback
(no pun intended) will be graciously accepted with thanks. Basically, I'm trying to figure out how to use my Blackstar Ht-1R as a "tone mod Althoughule", to be re-amplified by a fairly linear operating solid state amplifier with around 20 Watts output power. I guess you could say that I wan't to get the effect of miking it up to a P.A. without doing so. I don't want to use the emulated speaker and headphone output( which is or is not a line out by definition, depending on who you listen to). It's a shame that Blackstar will not make schematics available to the general public. Although I have hade several correspondences with their chief engineer, Bruce Kier. He has not replied to my request for more indepth specs such as impedance matching(which I believe is the main issue here), how they rate power output, nor any V-out, or I-out specs just to name a few that I requested. I don't have any experience with "re-amping", if that is the correct term, nor using a "slave amp", if THAT is the correct term. Please pardon my ignorance. I plan to build the solid state amp in kit form and am still researching just what there is out there. ANY advice or tips are greatly welcome as i am disabled and can't get around much to actively pursue info, except by such means as this.

May Your Tubes Never Dim,
Nor Your "Chips" never Fry,
Tonequester.

[soundguruman]

You hook it to an emulator, which takes the place of a speaker.
Still does not sound as good as mic-ing the guitar amp.

[J M Fahey]

What do you exactly want to achieve?
* The end idea is recording miked?
* Same sound but louder?
* Play with other guys? Drummer?
* More depth, balls "bigger sound"?
What speaker+cabinet will you use with the 20W amp?
* Not mentioned above?
Thanks.

[tonequester]

tonequester here.
First off. Beaucoup thanks given to JM Fahey and soundguruman for your replies. Second. The emulator. I have heard of them but have not heard one used.
I will check to see if my local shop/dealer has any. if so I will definitely give one a try. Sounds like I could just plug into the Blackstars speaker out. However, I really don't want any adverse effects on the tone that I get from the amp as is. Thanks again for the advice. soundguruman. Here's some more info. Yes the basic idea is to get a clean output/volume increase, just like one SHOULD from miking up to a P.A. I don't want the amps tone to be further colored by the power amp stage, if that IS where I'm going here.
I know that this will not be a "Holy Grail" situation. My ultimate tone(I believe) will be a combination of phase inverter/power tube overdrive, and perhaps some speaker break-up as well. For now $$$$$$$ ! After upgrading the stock tubes in the Blackstar to EH-12ax7 Gold, and JJ 12au7 Gold I'm closer than I've been before, and I must as well give kudos to Blackstars Infinate Sound Feature, no doubt complex integrated circuitry. The emulated output/headphone jack does not sound the same through quality headphones and with no hope of getting a schematic from Blackstar, I don't what the deal is there. Headphones produce a sound that seems like pure pre-amp distortion 30% to me. To fuzz-box.
Yes to playing with others(garage band), yes to a drommer, but NOT a pounder. The depth and balls are there in the amp, especially with about one third gain and full volume.
It's the loudest one Watt output I can imagine. It's louder than an Ibanez 15 Watt S.S. practice amp that I've got hanging around for no reason at all. Seems to me that i face an impedance matching problem at the least, and probably much more. The HT-1R's output V. and I. to name a couple. Can it be that some one makes a matching transformer that
would 4-16 Ohms Z., to about a 22K Ohm load ? There it is for now. I've probably let too much stupid out of the proverbial bag. If you gentlemen have any further thoughts, they are welcome. Thanks again for your time and effort. tonequester.

[mozwell]

the emulator out looks to be some basic filtering only, to simulate speaker frequency response.
This will not get you what you want.
Micing an amp through a PA only amplifies you existing amp sound, if you dont have a good sound from your amp, it wont get any better through a PA.
Get the sound right at the amp first.

Here is the HT5, which may be similar.
Also the ISF seems to be a filter in the input & changing the mid freq. You can see this on DS-2 HT. Nice looking circuit.

Hopefully these circuits (which i found on the net but cant remember where) will be useful.

[Chuck H]

Simulating the speaker response (and "kick back voltage") is impossible. Even the Weber MASS attenuator that uses a speaker motor can't do that (because there is no moving speaker). Most often the actual affect of the speaker is not as profound as to make it's omission unpleasant. So... Just use a ten or twenty watt resistor for the load and run a typical "speaker driven line out" (can be found searching the forum). This basically turns your amp, power tube included, into a preamp that can then be re-amplified by another device. I would still suggest the use of guitar amp speakers for the final tonality.

JM2C

[soundguruman]

you can always try an amp in an isolated location with a microphone,
Rundgren / Zappa style,
but an emulator or attenuator never sounds as good.
This dilemma has plagued guitar players for days eternal...
It had recently been suggested by my old acquaintance Glen Kuykendall, to install a field coil speaker, with a variable DC power supply for the field.
In this way the magnet strength and therefore the volume of the speaker can be adjusted, also the field coil is less efficient and therefore quieter.
And yet Seymour Duncan used the patented voltage regulator master volume to adjust the voltage and the bias simultaneously for the output tubes.

[tonequester]

tonequester here.

Thanks for the relies gentlemen ! Chuck H. The 10-20W. The 10-20W. load resistor and "a typical speaker driven line out" sounds like a simple enough experiment.
I have to admit that I don't as yet know what the speaker driven line out constitutes, but I will search the forum as you suggested. I salute you for the tip. mozwell, thanks for the schematics. I'm not sure, at first glance, if any apply to the HT-1R. Whether or not they do is nooo...problem. I haven't been able to find anything else on a Blackstar circuit, and I will
spend some time in study of the 5 that you were kind enough to supply. soundguruman. The notion of using a field coil speaker/variable power supply in that manner is an interesting
and intriguing idea. I haven't seen a field coil speaker in quite a while, but I would imagine that with a little perserverance one could be found, and I wouldn't think that it would be all that expensive. I probably havn't noticed any because I haven't been looking ! I would be interested to know more about your comment on Seymore Duncans use of the patented voltage regulator/master volume to adjust voltage and bias in concert to the output tubes. I of course know of his company and the pick-ups that he designs/produces, but that's about it. Was
this concept applied to an amplifier project that he was involved with ? Thanks a million guys. Once again I come away with more knowledge than I brought. I can only hope to one day
have a good thought/idea/tip, for someone in search for knowledge. tonequester.

[soundguruman]

I think some people would refer to it as "power scaling"
It was invented by this dude, but I don't know his name.
The available B+ is variable, regulated to the power tube...but steady for the preamp and filaments.
and the bias is scaled in proportion, with a patented thingamajig multi-tracking regulator setup.
as you know, when the volts is lower your bias may need adjusting, so this thing adjusts it for you.
the result is a "variable wattage" control, that theoretically maintains the correct bias for any given plate voltage.

[tonequester]

tonequester here.

Thanks for the quick reply soundguruman. This is interesting, and I've had another post that mentioned that I should try "power scaling", although he gave me no details.
I've listed it as one of the suggestions to "research". If I understand correctly, and I may not, the filaments are maintained at their specified value, and the pre-amp values are not adversely
affected. This circuit allows for one to attempt to "dial in" the tone that they are after by tweaking plate V. At the same time, you would not have the hassle of re-biasing every time you make a change at the plate. A self-correcting bias-power control. If I'm missing the boat, give me a point for trying and let me know when you can. Thanks a bunch. tonequester.

[Steve Conner]

A good explanation of how power scaling works, though I didn't know Seymour Duncan ever used it.

Power scaling is easy to apply to cathode biased amps. The cathode bias adjusts itself so no fancy tracking regulator is needed. I've had decent results by varying the screen voltage alone.

A field coil speaker for guitar amps is available, with a variable field power supply. It goes by the name Fluxtone, or something like that. Seemingly it works very well, but it is pretty expensive. Eminence make a permanent magnet version with a mechanical shunt to vary the field strength.

I'm sure you could pick up an old Jensen field coil speaker from a Hammond tone cabinet and make your own "Fluxtone".

[Tom Phillips]

Tonquestor,
The best source for information on "Power Scaling" is available at Kevin O'Connor's site at www.londonpower.com and there is a power scaling Q&A page at London Power POWER SCALING Q & A.
Regards,
Tom

[Gibsonman63]

Google Hall Electronics. It is quick, easy and cheap to install a VVR (Variable Voltage Regulator) on your B+ if you have a cathode biased amplifier. He sells a fixed bias version as well.

[soundguruman]

If you change the B+ you must also change the bias, fixed or not.

[Chuck H]

If you change the B+ you must also change the bias, fixed or not.

The cathode bias adjusts itself so no fancy tracking regulator is needed.

The self biasing characteristics of cathode bias should not be underestimated. But I agree in general. And idealizing suits my personality better. I've been known to write that power scaling is just a clever way to operate tubes poorly. Smarter guys than me have tried to explain it but I've never gotten my head around all the dynamics that are changing and how they affect each other in an analogous way. I have trouble believing it's a suitably linear adjustment on all parameters. But I'm not as tech as others here. Still, if cathode bias was truely self adjusting such that you could scale the voltages down quite low without bias consequences then why do we bother to choose a particular value resistor for a particular amp? One resistor value could be used for all amps in all instances!?!