v-4/vt-22 sensitivity question

[Hangman]

I have considered that, the only thing that really kept me from doing it was the fact that it is rather complicated. ( as you pointed out)

because it requires adding an additional tube and that tube is on the mid EQ/reverb board. which has to also be modified... i just didn't think it was worth it. too much work and too many places to make mistakes.

[tdbassman]

because it requires adding an additional tube and that tube is on the mid EQ/reverb board. which has to also be modified... i just didn't think it was worth it. too much work and too many places to make mistakes.
[/quote]

Thanks Steve. It's our playing season here and I haven't even had time to install your tone stack mod.

[Hangman]

perhaps what I might do in the long run, is make a replacement mid EQ board that has all the circuitry on the board, and then it would really just be wiring it up...but thats still quite a bit of work.

Im interested to hear what you think of the tone stack once you get it installed.

-steve

[tdbassman]

Im interested to hear what you think of the tone stack once you get it installed.

-steve
[/quote]

I'm looking forward to it too. Since most seem to prefer the 500pf or 250pf cap, have you tried something between the two (like a 360pf), and if so, what do you think of it?

[Liquids]

Not sure if the links work anymore, but I posted a bit about different configurations and had a screenshot or two here: http://www.ampegv4.com/forum/viewtopic.p...5061#p5061

I at least simulated the curve of where the default mid frequency is cut/boosted, corresponding with bass/treble pot settings, when modding the two treble side cap values (note that there are two caps for the high frequency range to work normally).

Stock is 470pf/4.7nf, but I also simulated 330pf/3.3nf, 220pf/2.2nf, and 150pf/1.5nf. I forget which ones I did and didn't audition with solder.

Per that post, I may have landed at 150pf/1.5nf, but I don't remember anymore if it stayed that way or if I settled on 220pf/2.2n.

I do find again and again that ~600hz is where I like a midrange cut to be centered for guitar amps run clean and with pedals for dirt. That is the center of the mid frequency cut when you boost the bass and the treble with 150pf/1.5n combo, more or less.

FYI, if the rest of the tone stack is left stock:
470pf/4.7nf = ~325hz (similar to most blackface fender deluxe/twin/princeton)
330pf/3.3nf = ~400hz
220pf/2.2nf = ~475hz (very similar to a stock blackface *Super Reverb*)
150pf/1.5nf = ~575hz

The things I like most about shifting the mid frequency center point higher are:
A) The sound retains more of the fat low-mids, to the ears
B) 'Boosting' the treble control does more in the 3khz+ range, while the resulting mid scoop still cuts a good dose of 1k and 2k, which the stock arrangement preserves/restores far more of 1k and 2k frequencies. The stock arrangement made it harder to set the treble control to suitably clarity but not fatiguing to the ears, with a guitar, IMO.

Stock, 300hz is a frequency you can control with the active mid control anyhow, so it seems redundant to have the baxandall controls centered rather close to that frequency too, IMO.
Likewise, 330pf/3.3nf seems too much like stock to be a noteworthy shift, but if one is really happy with the stock arrangement and doesn't ever find the EQ a little hard to dial in, it may be a good place to start if curious about other options.

The resistor between the wiper of the mid and treble pot has some affect on the midrange frequency in the baxandall, but far less than the caps.

[Hangman]

I had forgotten about that post! Well done.

I was trying to get good traces of that circuit using Multisim, but was having a hard time getting the potentiometers to sweep.

I think the 220pf/2.2nf combo that liquids recommends is probably a good choice. I agree too that The 330pf/3.3nf is probably not different enough to be really appreciated.

I haven't tried all of these combinations yet myself, but Liquids is correct in stating that the mid eq seems to get encroached upon by the treble and bass controls. giving it some more room is not a bad idea.

[Liquids]

Should note that I run my amp dead clean. The dirt pedals I use have active 12db HF cut at a pot-controlable frequency, so I can have a fat, sparkly clean tone, then kick in a high gain overdrive pedal that has a sharp cutoff at X.Xkhz so there is exactly as much high end as I want for clean and for high gain.

I think the stock tone stack is probably nice if you drive the amp for marshall crunch, in that you get some of that 1k-2k boost with the stock tone stack past noon, and the marshall-based (esp JCM800 and hot rodded versions of those) circuits really get a lot of benefit from RC networks that are voiced to accent these frequencies.

Pot sweep on the knobs on the V series is odd--knobs are anti-log, I think. You'll get a lot of play on the opposite end you might expect. Pots set at noon/flat is a voltage divider set closer to 100k/900k than 500k/500k.

[tdbassman]

Should note that I run my amp dead clean. The dirt pedals I use have active 12db HF cut at a pot-controlable frequency, so I can have a fat, sparkly clean tone, then kick in a high gain overdrive pedal that has a sharp cutoff at X.Xkhz so there is exactly as much high end as I want for clean and for high gain.

This is nice to know, but what I'm really looking for are cap configuration suggestions for PBass with flats. I use it for old school rock - for which Ampeg's are famous, and for big band. I realize sound is pretty subjective, but are there any schools of thought and has anyone have experience with this? I want to avoid continuously soldering / unsoldering from the board.

I've never thought of runing my guitar through the V4-B, as I've got some different (lighter) amps for that.

[Liquids]

OK...when you use the mid control, which frequency setting do you use if you are "cutting" the mid pot--that is, below noon. And/or, if you ever set the mid pot above noon, which frequency setting do you use? that might help. Likewise with where you ususally set your tone knobs, and any other sentiments you have about the tone, settings, or things you 'can't quite dial out', etc.

[tdbassman]

OK...when you use the mid control, which frequency setting do you use if you are "cutting" the mid pot--that is, below noon. And/or, if you ever set the mid pot above noon, which frequency setting do you use?

Thanks, I'll have to take a look at the settings.