Best way to increase bass response...

[Bob M.]

Hi,

I've got a homebrew that I like alot with one exception. It's too bass-lite for me. I've got good sized iron for both power and output transformers so I don't suspect the problem is there. I'm using a favorite 12" speaker that has tons of bass in other amps I have so I don't really suspect the speaker as the source of my lack of bass response. All cathode caps are bypassed with at least 25uf@50 VDC. I could slightly increase these but I don't want woofiness which I found to be the case in the past with runaway cathode values.

I think it comes down to increasing the coupling caps or increasing the filter caps (and probably only the first filter cap). What's the best route here and in what area will I most likely achieve my goal. It's a very simple circuit, no effects, 4x tubes - two of which are 6L6s. I appreciate any and all on-point comments.

Bob M.

[tedmich]

25uF at the cathode bypass caps of your typical 12AX7 gain stage should boost everything above ~10Hz. Its probably going to be the coupling caps you want to tweak but maybe a full schematic would help get the ideas flying!

[cbarrow7625]

+1 on the schematic, if possible. Does this amp have feedback around the power section? What type of phase inverter?

[pdf64]

Failing a sketch / scan of your schematic, how about just a description of the various stages, in comparison to standard types already in the public arena, eg ab763 deluxe reverb normal channel and phase splitter, into a 5E3 power amp / power supply.
And what other amps, which have a good bass response, are you comparing it against?
Pete

[Bob M.]

More Bass...

Sorry, I apologize for my minimal computer skills. I don't have a scanner and I'm not sure that I've even drawn up an exact schematic of this amp. I can tell you this. In the first preamp stage I'm using an EF86 pentode tube. Next is the tone stack, then the PI which is a long-tailed pair using a 12AX7A tube in a very familiar configuration. The power tubes are next (2x 6L6GC) and it is a fixed bias amp. The output transformer is ultralinear with no negative feedback and I'm using a solid state rectifier. It's a very simple circuit but sounds really nice. I guess my question is more theoretical than applied. Do I want to be increasing bass response via opening up the coupling caps (only 3 or 4 in this amp) or do I want to increase the filtering or should I try some of both? I guess I could also fool with the tone stack values or bypass it as an experiment to see what I'm throwing away.

My basis for comparison is all the amps I've ever played through and/or owned or heard. I have way too many amps (nearly 50) and although the sound of this amp is passable (bass frequency-wise), I'd be alot happier with a bit more low end. I'm just wondering about ideas to how to achieve it.

Bob M.