59 Bassman ?

[chuckb]

Hey guys,
I'm trying to lower the bass on my 59 bassman build and gie it more brightness. I've changed out the coupling caps for smaller values and I've changed the Cathode bypass cap a larger values with not much response.My treble doesn't change to dramatically from off to full on either. I have the correct pots and they work as they should but just not a big change in the tone. Can someone point me in the right direction on how I can possibly create a lower bass response and while adding more treble response to my eq section? Thanks in advance for your help here.

Chuck.

[EFK]

You should be using smaller value cathode bypass cap on the first stage, not larger. Try 10uf on V1, which is subtle, then try @ 2.2 uf or 1 uf if more bass reduction is desired. Are you using a 12at7 or a 12ax7 in the PI? 12at7 tightens a lot of the woofy, muddy bass.

[chuckb]

Yes, thanks, I'll try the smaller cathode bypass cap on V1 and I am usuing a 12ax7 in the PI,I'll pick up a 12at7 tomorrow and give that a try. I'm curently using all 12ax7's right now. I'm waiting on a 12ay7 and a5751 to come in for V1 as well.

[Jazz P Bass]

Try a 12AT7 in V1 & V3.
V2 is tone control. I would leave that as a 12AX7.

[chuckb]

Cool, I'll give those a try,I just have to pick up more of the same.

[txstrat]

What speakers are you using?

[chuckb]

Hey txstrat, I'm using just a 16ohm 12" Eminence Ledgend for now but Have a 212 cab loaded with G12m greenbacks that I'm plan on using as soon as I get the 212 baffel board finished. I tried the 2x 12at7's1n V1 and V3 but didn't like the tone.Lowered the cathode resostor to .1uf also and it made some difference in the degree of brightness. I still don't have much sweep on the treble pot though,really not a lot of difference from start to end.

[JoeM]

Try lowering the value of the PI input cap. Stock is .02uf. Try .001 or .0022. You have 2 12s in this amp? What ot?

[chuckb]

I have a set of transformers in this build that came out of a Gibson Saturn GA-45 RVT. I did lower the PI input cap to .01. I'll try your suggestions and see what kind of response I get with the .001 or .0022 uf caps. I currenty only using one 12" Eminence Ledgend 16ohm speaker right now but I do plan on trying 212 G12M greenbacks.

[chuckb]

The output on the schematic I have for the GA-45 RVT is 2x8ohm speakers wiried to 16ohm.

[chuckb]

Only one 16ohm output on the output transformer.

[txstrat]

Hey txstrat, I'm using just a 16ohm 12" Eminence Ledgend for now but Have a 212 cab loaded with G12m greenbacks that I'm plan on using as soon as I get the 212 baffel board finished.

The circuit of the Bassman hasn't been known for a lack of high end, although it was intended to be a bass amp.
Have you ever considered to try different speakers? Compared to a Jensen C12Q or C12N the Eminence lacks a good amount of high end, as well as the G12M do IMHO.
What I'm saying is, that before you start to tinker in the circuit you might try a different speaker and get the same, or even better result.

[chuckb]

Hey txstrat,
Yes,I have considered using different speakers like the C12Q or the C12N , I didn't have any of these on hand at the time and used what I did have. But your right ,I should aleast try those options before I mess with the circuit. So do you belive that Jensens will give me the desired response to the highs I'm looking for? I can pick up a set of these but I want to make sure that it's going to be a good choice. Any other speakers I could consider trying? By the way,Thanks for your input,I really appreciate it.

Chuck.

[txstrat]

I have a cab with an Eminence Guitar Legend 125 and several cabs with Jensen speakers.
The Eminence was my first buy and frankly I wouldn't have bought it if I had bought the Jensens first.
Don't get me wrong, the GL125 is a great speaker and I like it very much, BUT is has much less chime than a Jensen IMHO.
IMO the GL125 speakers are good for amps with two (say American and British) voicings, they're a very good compromise.
If you go for the sparkly Fender sound only, I would go for a Jensen.
Can't you borrow a Jensen anywhere just to have a quick listening test for comparing purposes?

[chuckb]

Hey txstrat,
I hear ya when you say the Eminence is alright for a two voicing amps and personally I'm not to struck on them anyways. I received a couple of them when I did a repair job for a friend of mine. I may go into Ebay and see if there's a pair of Jensen I can get. What would I try ,C12n's or C12Q's. or one of each? I only have a 10" jensen here at the moment. I could try an amp tech friend of mine if he's got one.

Chuck.