Coupling capacitors for V1 V2.

[Mr.Death]

Im in the final stages of modifying my YBA-3 Traynor. Next thing to address are the coupling caps. I see different values for the coupling caps for the different stages of the preamp. Should I keep the values for V1A and V1B the same like Marshall 2204(.022uf)? As it is I have a .022 from V1A going to V1B and from V1B the cap is .1 stock.
Should I change that value to .022? I want to tighten up the low end as it is a bit loose. Looking to get more of a high gain tight kinda sound.. Thanks.

[pdf64]

In conjunction with the circuit source and load resistances, coupling caps form high pass filters.
ie your query is missing essential supporting info, namely what those resistances might be.
If you don’t know, an accurate schematic would be helpful.

[sluckey]

Just get a handful of caps and change away until you are happy.

[Mr.Death]

In conjunction with the circuit source and load resistances, coupling caps form high pass filters.
ie your query is missing essential supporting info, namely what those resistances might be.
If you don’t know, an accurate schematic would be helpful.

I will supply that schematic. Ive made many mods to this amp so I need to do some tweaking to the schematic. Thanks for the reply.

[Mr.Death]

Schematic. Thanks.
Rick.

[thetragichero]

i would go 22nf on c33 personally

[Mr.Death]

i would go 22nf on c33 personally

What I was thinking but wanted to check with the pros before making the change.

[thetragichero]

i've never messed around with their guitar amps but i've had several yba-1/yba-1a which are a few components away from a marshall plexi, but a bit too much low end (make great metal amps regardless because they're loud and thick and just begging to be hit with a dirt pedal for distortion). all in all these old traynors are great amps and you can still grab em for 300 bucks or less from time to time. and just asking for mods

[Mr.Death]

i've never messed around with their guitar amps but i've had several yba-1/yba-1a which are a few components away from a marshall plexi, but a bit too much low end (make great metal amps regardless because they're loud and thick and just begging to be hit with a dirt pedal for distortion). all in all these old traynors are great amps and you can still grab em for 300 bucks or less from time to time. and just asking for mods

This is a bass amp as well. Super easy to modify.  Loud as sin.

[pdf64]

The old rule of thumb to avoid rolling bass off with RC coupling is for C x R = 10
C in uF, R in k ohms.
That gives a corner frequency of about 15Hz.
Obviously Fender went with ‘22’ rather than ‘10’ in most places, giving a corner frequency of about 7.5Hz.
With guitar I usually go a bit smaller, eg 5 or 3.
So for C3, with the R term a bit over 1M, I suggest something in the range 4n7 to 2n2F.

C33 is a bit trickier, as it’s feeding a stage with a local NFB loop, for an active midrange control.
Its input impedance is about equal to the resistance between the input and its ‘virtual earth’ point at its grid, so 68k, R4.
That’s effectively in series with the source impedance of the preceding stage. If its cathode was fully bypassed it’d be about 40k, however as it’s unbypassed, it’s somewhere between that and the anode load resistor value 100k.
I’ll guess at 82k then the total R term can be 150k.
Hence if C x R = 5, then C will be 0.033nF.
So something in the range 47n to 22nF should give full bass, maybe try 10nF if wanting to roll off a little deep bass.

[thetragichero]

depending on how tight you're looking the bass to be, also take s look at cathode bypass caps. something smaller (100nf like soldano to 680nf like marshall) can be beneficial on early stages, and you can always use the disconnected polarity switch to switch on a bigger cathode bypass cap in parallel when you're looking for fuller clean tones

[Mr.Death]

Here's a more detailed schematic.  Everything in blue is a mod. I added a switch to select different values for the cathode for V1 pin 3. I'm going to try .022 and see what it sounds like. Can always swap it out...