another noob hrdx mod'r

[mr.jetski]

I just don't want to buy AES for a good part inventory to mod with. any help greatly valued.
steve a. great site to read !
pre=gt12ax7a x3
power=gt6L6ge matched 9's old red style NO break up
bias @ 60mv no other mods done

[Enzo]

Hi, welcome to the forum. We don't charge by the word here, so maybe a little expansion of just what you are asking, what you want to accomplish, and so on.

[mr.jetski]

thank you enzo
I want to have a parts drawer in my tool box of the most used parts <oramge drops, silver mica caps > resistors etc... so I don't have to call AES every 5 minutes
In the past week or so i have learned enough about amp modding to know I know nothing
just want a more full rich sound clean,drive and more drive
on the plus side, a 250k nl pot for hrdx is available at aes 2 will be installed shortly

[Enzo]

Look at a few schematics of the type amps you like. I think you will see a number of common parts values.

A selection of 5% half watt resistors - off the top of my head:
100k, 220k, 470k, 1meg, 68k, 47k, 1.5k, 820 ohm, etc.

There are higher wattage types used, but I don't see them as often, at least not in the repair game.

AES is a fine place to find parts we use a lot, but for stocking orders, you might also look at Mouser, Allied, Digikey, even Jameco. Prices on resistors often drops dramatically if you buy 100 of them. For example Mouser, 100k 1/2W carbon film resistor. The KOA is 19 cents each but 3 cents in 100 lot, or the Xicon is 9 cents each or 1.6 cents in 100s. In other words, 15 resistors will cost the same as 100.

Caps have value AND voltage ratings. You can always use higher voltage caps than you need. Only issue is they get larger with voltage, so in rare cases if it is a tight fit... Point being that I stock the 600v film caps instead of 600v, 400v, 200v, 100v, etc. Again common values for film caps might be: .1uf, .047, .022, .01, .005, .001. Anything smaller is probably a disc or a mica. And don't sweat the difference between .047 and .05. Orange Drop, Mallory? Take your pick. If you actualy develop a preference at some point, then stock one type. At first anyway, I think there are other things to worry about.

YOu will probably use fewer of the smaller value parts - the ones in ceramic or mica, but you might want to tweak values more, so a spread of them would be useful. 820pf, 500pf (470pf), 330pf, 220pf, 270pf, 180pf, 150, 120, 100. 47. Some of those might go in the tone stack, while others might be brightness caps on volume controls.

Check Mouser etc, for price. a 220pf 500v ceramic disc cap there goes for like 10-15 cents.

COnsider a cap kit - a plastic sectioned box with like 5 of each value through the series. Watch the voltage though, a lot of kits are 50v caps. Not enough for tube amps. OK across a volume contril yes, but not coming from a plate to a tone stack.

Electrolytic caps: SOme values you see all the time are 25uf/25v for cathode bypass duty, and the ever present 22uf/500v for filter cap use. Also 10uf/500v is common. Axial leads are most common in guitar amps

[mr.jetski]

I want to do the math behind some of the caps and resistors. I'm 1 of those guys that likes to know the reason for it being there. eg... I know nothing
I know enough to mess it up really bad

[mr.jetski]

2 things

does anybody have schems on a rockmaster preamp or valveverb?

i would like to add the rockmaster ultra channel to my hrdx

[Enzo]

Yes, Peavey has them. Call the folks at PV and ask for them.

[Gtr_tech]

2 things

does anybody have schems on a rockmaster preamp or valveverb?

i would like to add the rockmaster ultra channel to my hrdx

I have the print on the r-master, but its on me other machine...which has m-board problems at the moment. Gimme a day or so to get that taken of and if you still don't have it I'll email it to you.

wait.....its right here:
http://www.schematicheaven.com/newam...ter_preamp.pdf

[mr.jetski]

thanx for that schem man thats cool

I really liked the sound of this circuit - kind of a combination of the best characteristics of SS-diode and tube distortion.

this diode form would go where in a hrdx? after the drive pot?
I really want it in more drive so maybe r20 --> r21