any amp tech here? Few questions about ACE.

[gonziak]

Hi guys. I bought stiletto ace combo, I've got a question about phase inverter Output Coupling Caps it has .022u and no so much bottom as 0.047u caps. I'm thinking about why they put only .022? It's noticable lows difference with 0.047, but how about el34 with 0.047 could it ruin the ace's tone?
I put preamp based on balckface fender in return loop and the clean sound of my strat is absolutely improve what do you think about change tone stack of chnn1 to more blackface character. It will ruin the crunch but clean will be great.
thanks

 

[Boogiebabies]

The .022 is the classic Marshall value. The Stiletto is a direct attempt by Mesa to build an all tube high gain Marshall / EL-34 based circuit. I don't have a schematic, but, Mesa's current designs for multi channel amps have Fender pre-gain tone stacks in them already and then switch them to a Marshall post gain type tone stacks for high gain circuits. The Ace may, or may not have a Fender type tone stacks for cleans, but Mesa has recently employed circuits that use transistors to swap cathode cap and resistor values to change the voicing of each channel. Earlier Mesa's use the .047 and the MK Series generally used a .1 after the PI and were either Simul-Class or 6L6 designs. You can try any value you like, but the circuit board will not handle multiple attemps before the pads lift. From a modification stand point, if I just bought an amp and immediately started thinking about mods, I would ask myself if I bought the right amp for what tone I was looking for.

 

[Guitarzan]

+1 to above. It is what it is.

 

[Platypus]

+1 indeed

 

[gonziak]

Thanks a lot Boogiebabies . I moved to stiletto ace combo from 68 plexi cause of ace's drive channel. I'm very happy how it sounds, but clean channel could be more twangy with strat, I looked inside the ace and clean channel has marshall type tone stack. I'm just wondering about give the amp to mesa service and add push pull knob for tone stack switch marhall/fender but Is it make sense? Would I get more twang with such mod?
I asked about .047 or .1 u cause when I put ace to 1960 ax Greenback cab there is no such lows when I got from Plexi with 0.47, but I don't know how El34s in ace board would handle 0.047 only add lows or loose his great drive.
Mod is cheaper than buy next amp for clean sound. When I put preamp based on blackface in ACE I got satysfying twangy sound on clean chn - straight to pwr amp and main input.
Is the ACE use same tonestack to both channles
(switched between potentiometers) or 2 separate
Have you checked the simens mesa el34?
Thanks
I'm just wondering about that, I don't even think about to do it myself.

 

[Boogiebabies]

Hey, no problem on the info, but it's still just based on how I assumed the Stiletto's preamp was designed.

I have worked on newer Mesa's and they are not very easy to modify.
Knowing how they cram circuits i think it would be nearly impossible to add a Fender tone stack to this amp. The traces are too delicate and most times too difficult to trace. You can mod a bunch of components, but it would be a ton of work and serious knowledge to design a new tone stack what incorporates the relays and switching transistors. If there is one thing Mesa can make complicated is it's switching systems. You would need a schematic and a truth table to see what gets switched in or out and when. If you want a Fender type clean, the RK II uses a Fender tone stack and even goes as far as using carbon comp resistors in the clean circuit. As an added benefit, you can use two EL-34's on any channel for a hot rodded Marshall vibe. If you want to go with 2 6L6's and 2 EL34's you will encounter a wicked ride of bottom end and the cut from the EL-34's.

As far as the Siemens EL-34, i have Mesa, GT and no label versions of each. I have 12 in total and I have used them in Marshall's and IIC+'s and the RK. They are a superior tube, but you may want to keep them under 450 volts or they tend burn out quickly. SED's seem to give a very close tone and can handle the higher plate voltage with a much longer lofe span. Like the STR-415's I only use the Siemens for special occasions. I'm a wuss who dreads using an expensive and nearly extinct resource unless I need to. For recording a certain tone I would use them, but for the punishment of gigging, I use the current stuff because I would probably have a major bout of depression if I killed a NOS tube.

 

[gonziak]

Thanks a lot, and best wishes from Poland