Cutting Some Bass on D'Lite

[Structo]

After installing the new Prosonic OT in my D'Lite 44 (6L6) and playing for some time at a good volume it sure seems to be bass heavy. I don't think the new OT did this, I just haven't played it at a loud volume in quite some time.

I am running a 2x12 with Tonkerlites at this time and it is on the floor so I know that is contributing but it just seems when it is loud that the bass is heavy even with the bass pot all the way down.
This is with a strat with vintage wind single coils.
This amp has the high plates and 4.7uf bypass caps on both V1 and V2.

I do not have the jumper on the bass pot as I removed that a long time ago to cut the bass.

I can't remember if I have a .05 or .01 mid cap now but I was thinking of installing a 250K mid pot (100K now) and making sure I have a .01 mid cap.
Also, can the bass cap which is a .1uf be lowered to cut some bass?

I have the .001uf and 10K on the bass pot itself.

[dave g]

What is your V1b coupler? Kicking that down a bit is usually very effective.

[Structo]

I believe it is a .05uf orange drop.

I see on the later Tweeked Layout it is changed to a .02uf.

Will that affect the OD channel as well?

I think I'll try that and also install the pre OD entrance mod 220K + .05uf cap.

[greiswig]

IIRC you already have put a cap in front of the OD entrance to reduce bass going into the overdrive, right? Is it bassy in both clean and OD?

Where I seemed to find some balance between OD and clean was in playing with the cathode bypass caps. I don't remember what I settled on, but the OD side in particular is in the 1-2uF area for both v2a ND V2b. To my ear, this is more of a fine-tuning approach...a bit more subtle than changing the OD entrance cap. Almost as if the knee is not as hard and the slope is less steep.

This opinion worth every penny you paid...

[Structo]

No I never installed the OD entrance mod.

Yes I would say it is too bassy in both channels.

If I switch on PAB in clean mod it sounds terrible, too much of everything.
I seem to remember padding that with a 4M7 resistor.

As far as bypass caps I have 4.7 on all except V1b which is 10uf.

If you are familiar with the Tweeked Layout that Moss made, I have pretty much all of the mods done save for the OD entrance and V1b coupler which is still at .05uf instead of the .02uf on the tweeked layout.

I value your opinion because I know that you have done a lot with this amp.

[JimiB]

V1b coupler which is still at .05uf instead of the .02uf on the tweeked layout.

Change that to .02 or .03 (i like the .03)

[dave g]

If you have a 10uF on V1b then yeah, you're definitely going to want to reduce that coupler. Personally I tend to like a lot of bass on the clean channel, but I prefer a little less on OD.

I have found that I always like reducing the coupling cap rather than the bypass cap in order to get less bass. Even going through the calculations and tweaking to get the same knee frequency, I prefer the sound of a larger bypass cap with a smaller coupling cap rather than the opposite....YMMV.

I'd say if you're going to leave the V1b bypass cap at 10uF, then take the coupling cap down to .02. If it's still too much, go .01. If you still have too much bass on OD, then fiddle with the additional series coupling cap in the pre-OD network. Anything in the .01 to .05 range there is worth a shot.

[Structo]

Scott and others have helped me with tips about tuning this amp and it has helped this amp a great deal as far as getting it to sound more like a Dumble.

I guess what I have a hard time understanding is that do I have to make adjustments across the board ( couplers, bypass and resistors) to lower the bass response or is there a key area to zero in on that will do this such as just adjust the bypass caps on both preamp tubes?

I'm probably trying to over simplify it but when you start moving everything around you kind of lose sight of your baseline or foundation of the amp then end chasing your tail trying to figure out how to get it balanced again so that the tone stack is affective in controlling the three areas of frequency.
I understand how they are interactive with each other but when I turn the bass all the way off and the bass is still too heavy at volume I need to change something.

At low bedroom (or loud bedroom) levels it's fine because you aren't pushing anything.

It's just at more of a gigging type volume is where I am having trouble.

[Structo]

If you have a 10uF on V1b then yeah, you're definitely going to want to reduce that coupler. Personally I tend to like a lot of bass on the clean channel, but I prefer a little less on OD.

I have found that I always like reducing the coupling cap rather than the bypass cap in order to get less bass. Even going through the calculations and tweaking to get the same knee frequency, I prefer the sound of a larger bypass cap with a smaller coupling cap rather than the opposite....YMMV.

I'd say if you're going to leave the V1b bypass cap at 10uF, then take the coupling cap down to .02. If it's still too much, go .01. If you still have too much bass on OD, then fiddle with the additional series coupling cap in the pre-OD network. Anything in the .01 to .05 range there is worth a shot.

I was typing when you replied Dave.
The 10uf is the bypass cap on V1b.

How much does the tone of V1 affect the OD tone of V2?
If I thin the tone on V1 will that thin the tone on V2?

[greiswig]

How much does the tone of V1 affect the OD tone of V2?
If I thin the tone on V1 will that thin the tone on V2?

In my limited experience, if you have a bass problem on OD, by the time you've thinned out the clean side to where the OD sounds good, the clean side will sound too thin. But if I read you right you're describing something on both clean and OD channels?

One thing: a room can really fool you. Move the amp around and make sure it sounds bassy everywhere before you try to fix the amp.

[dave g]

How much does the tone of V1 affect the OD tone of V2?
If I thin the tone on V1 will that thin the tone on V2?

In my limited experience, if you have a bass problem on OD, by the time you've thinned out the clean side to where the OD sounds good, the clean side will sound too thin.

That's why the additional series cap in the pre-OD network is so critical, and why that location is the best place to tweak for this sort of thing. The very first thing you do is tweak for the clean side only, choosing a cathode bypass capacitor/coupling capacitor combination that gets you the right amount of clean girth. Then, you go in and tweak the cap in the pre-OD network. That way, you can limit the bass going into the OD section without having an effect on the clean channel.

[frischmann]

Interesting,
I don't seem to have the bass issue. I just snipped the bass jumper and am amazed at how much more balanced the amp is.

I'm using a Ruby Tubes Bassman OT and a pair of G-1265's.
I do find the tweaked tone stack interesting. The mids are more like low-mids, at least with the Skyliner set up.

[Structo]

How much does the tone of V1 affect the OD tone of V2?
If I thin the tone on V1 will that thin the tone on V2?

In my limited experience, if you have a bass problem on OD, by the time you've thinned out the clean side to where the OD sounds good, the clean side will sound too thin. But if I read you right you're describing something on both clean and OD channels?

One thing: a room can really fool you. Move the amp around and make sure it sounds bassy everywhere before you try to fix the amp.

Gotcha, yeah a room can influence the acoustics a lot.

Right now I am in a small bedroom.

I think both channels could use less bass, especially when the volume is up.

The PAB is not very usable on clean, so maybe I need to pad that more.

I did build a resistance decade box the other day so I can use that in some spots to figure out some values.

I think I'll experiment with some coupler values.

I wish I had a cap box too. I know I can just tack some components in to try them.
Every time I think I have this amp figured out, I realize I don't know that much!
I mean, I understand how it works and the signal flow, but as far as the R/C networks and how they change the tone, I'm still pretty wet behind the ears.

And at 52 I guess I should know this stuff by now but tube theory wasn't really taught by the late 70's so I've had to learn this stuff on my own.

[greiswig]

In my limited experience, if you have a bass problem on OD, by the time you've thinned out the clean side to where the OD sounds good, the clean side will sound too thin.

That's why the additional series cap in the pre-OD network is so critical, and why that location is the best place to tweak for this sort of thing. The very first thing you do is tweak for the clean side only, choosing a cathode bypass capacitor/coupling capacitor combination that gets you the right amount of clean girth. Then, you go in and tweak the cap in the pre-OD network. That way, you can limit the bass going into the OD section without having an effect on the clean channel.

Agreed. That's what I was trying to say: thinning out the clean side to fix a bassy overdrive will not work out well.

[frischmann]

I wonder if that's why the HRM was developed..?