Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: m3moser on July 19, 2012, 04:08:39 pm
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Hey Folks- I have a request for a 25 to 50 watt clean amp to be used as a basis for high gain metal style pedals to be plugged into the front end. You know, those pedals like the Mesa Twin V or those Damage control or other "preamp" style pedals. The customer wants to keep it in his studio along with a collection of these pedals for his high gain clients. Its really just a pretty plain mostly power amp build, I am just looking for recommendation on which circuit might fill the bill.
Any ideas?
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AB 763
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Hi m3, found this in my schems, i don't know much about it but its called CLEAN TONE?
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AB 763
What he said! +1
Classically clean and pedal friendly
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I love my AB763 Deluxe Reverb, but for clean tones I'd go 40 watts or better.
sky
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I'd go with the normal channel here: http://www.el34world.com/charts/Schematics/files/fender/bandmaster_ab763_schem.pdf (http://www.el34world.com/charts/Schematics/files/fender/bandmaster_ab763_schem.pdf)
Tighten up the 1st stage filtering value to @100uF (stock is 35uF). Can also try increasing the Screen filtering, but not as drastically as the 1st stage. You want tight, yes ? To sound best with high gain pedals, but not necessarily the best set-up for use without these types of pedals/preamps ?
Use this OT: http://www.classictone.net/40-18001.html (http://www.classictone.net/40-18001.html)
I'd also use the stock Fender input jack configuration---- the padded input (jack 2) could be useful if the customer uses a seperate high gain preamp or a high gain pedal with an unusually hot signal--- It would give an extra measure of versatility--- you never know what someone is going to bring to a studio to record with.
Install a 10K pot in place of the 6.8k resistor from bass pot to ground to add Mid control (or see this AB763 Showman schematic): http://www.el34world.com/charts/Schematics/files/fender/SHOWMAN_AB763.pdf (http://www.el34world.com/charts/Schematics/files/fender/SHOWMAN_AB763.pdf)
If you want a head that would have deeper/more detailed sound then build the 85 watt Showman version--- with similarly increased 1st stage filtering---- The extra power is probably not needed in the studio and would require speakers that would handle the power level.
I'd go with the Bandmaster AB763 version(with stiffer filtering)-- One of my BF Bandmasters is similar to this idea (has Heyboer BF Bassman-type 4/8/16 OT---amp was set up before Classic Tone came out with their great sounding and cheaper OT)---- this one has stock Fender filtering values and has been used on several recordings, as a pedal base, but gets a little too loose when used with true modern high gain preamps and low guitar tuning-------One modern metal band brought over their guitar and rack preamps and were looking for a tube poweramp----- a Hiwatt DR103 clone i did worked better than the Bandmaster for them--- but they were playing at very high vol levels and driving the Bandmaster into clipping----after finding out how much Hiwatts (and Hiwatt clones) cost, they decided to stay with their solid state poweramps--- Hiwatt circuits aren't simple or cheap to build------ Bandmasters work well as pedal platforms within the practical limits of their volume output potential.
Advantages:
Simple to build
Parts easily available and reasonably priced
Sounds terrific
Disadvantages:
None
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Thanks Guys- let me look these over then discuss with the customer. I see a few things here to chew over and recommend to him. I appreciate the recommendations on this!!