Ways to achieve clearer bass responce (nonHRM)

[mat]

I would like to know different ways to make d-style builds to have more definition on the lower end on the overdrive side. I know basicly everything affects everything but would like to know anyway lots of different basic ways to tame the bass fuzzines and have more articulate low notes.

Lets hear them:

1.

2.

...

[talbany]

First thing I would try is some different preamp tube combinations in V1 & V2
before firing up the iron.. Sometimes preamp tubes with a higher mu will help tighten a loose low end..If the tubes don't quite do the trick you may want to look at lowering your bypass caps on v2b and possibly v2a...Good Luck..

Check your voltages too.Shoot for 200v V1a


Tony

[dave g]

If we're talking about just the non-HRM here...

I like 5uF bypass caps on both stages. I've tried 1uF on OD2 several times and didn't like it.

My favorite way to improve the clarity of the bass in OD is to drop the OD1 coupler from .01uF to maybe .005 or .0068 (maybe even .002 if it's really bad)...then I usually raise the OD2 coupler to .01uF or .02uF. Since practically all of the clipping happens in OD2, this limits the ability of the bass frequencies to drive that stage into clipping, but in turn you're attenuating them less on their way out of OD2. The end result is a cleaner but still strong bass.

[exocet]

There was a thread on this subject some time ago

https://tubeamparchive.com/viewtopic.ph ... t=entrance

I'm looking at tweaking some of the coupling cap values around OD2.

Do you have a 0.0012 Bass cap? I did on mine because 0.001 in 6PS are difficult to obtain in the UK. I have now managed to source a few and will give these a whirl as that will impact on overall bass response.

[mat]

Lets hear more, maybe including PI and power tube section also.



clearing the nonHRM OD bass tips:

1. try some different preamp tube combinations in V1 & V2

2. way to improve the clarity of the bass in OD is to drop the OD1 coupler from .01uF to maybe .005 or .0068 (maybe even .002 if it's really bad)...then I usually raise the OD2 coupler to .01uF or .02uF. Since practically all of the clipping happens in OD2, this limits the ability of the bass frequencies to drive that stage into clipping, but in turn you're attenuating them less on their way out of OD2. The end result is a cleaner but still strong bass.

3. If you use larger bypass caps or lower plates on V1 (or both) series in another .05 cap after the relay so the OD gets less bass. Adjust cap value to taste.

4. OD entrance mod on the grid of V2a: trimmer, 220K, .02uF to OD relay.

5. Add a 10M resistor from the .05uF cap to the bypass ground of V1.

6. 1uF bypass on V2b

7.

[llemtt]

My favored configuration for V2a is 1u bypass and 22n coupling. Very recently I moved one of my high plates amp to standard specs (i.e. 5u bypass and 10n coupling) and, although the overall response of the stage is approx equal, the overdriven bass notes became to much fuzzy...

So I am going back to the 1u bypass very soon.

Interestingly I have another hybrid amp (tube pre/solid state poweramp) with standard values and it doesn't sound so fuzzy. I always stand that there are lot of other details in these amps, apart from component values, that have HUGE influence on how they sound!

my .02
teo

[Structo]

OD entrance mod which is used on the grid of V2a, which is:

Trimmer, 220K, .02uF to OD relay. That will thin the bass quite a bit.

Add a 10M resistor from the .05uF cap to the bypass ground of V1.
That will thin quite a bit from the bottom on the OD.

You can try a 1uF bypass on V2b, I have used that before and may go back to it.