TOO MUCH BASS

gary sanders · Post by **gary sanders** » Thu Feb 03, 2011 7:38 pm

Its really not a problem as long as I have the bass pot at about 7:00 but even half way its booming.Went by the 124 schematic but as I was changing the direction of my caps I put a .01 as the mid cap like on the 183.Using 4.7 cathode caps,a .1 on the bass,could the 33uf filters instead of 22uf in the power supply be causing this?

exocet · Post by **exocet** » Thu Feb 03, 2011 8:17 pm

gary sanders wrote:Its really not a problem as long as I have the bass pot at about 7:00 but even half way its booming.Went by the 124 schematic but as I was changing the direction of my caps I put a .01 as the mid cap like on the 183.Using 4.7 cathode caps,a .1 on the bass,could the 33uf filters instead of 22uf in the power supply be causing this?

Too much bass compared to what?

I think that the bass is quite 'strong' especially when played 'in the house', I recently opportunity to play on stage a 'giging levels' and it was absolutely fine. If I hadn't done that I'd probably be looking to lower bypass cap on V1b or change a coupling cap. As it is, I'm leaving things just as they are.

gary sanders · Post by **gary sanders** » Thu Feb 03, 2011 9:13 pm

Just from what you would typically have a setting at 100%,its giving me that at about 25%.Just want it to be "right" I guess.It really helped the mids to change the mid cap from 047 to 01.

Structo · Post by **Structo** » Thu Feb 03, 2011 9:24 pm

Yeah, the ODS can have a lot of bass depending on the speaker cab.

In the Rock setting my amp has a ton of bass.

gary sanders · Post by **gary sanders** » Fri Feb 04, 2011 2:37 am

And its only with the overdrive on and PAB off...snubbers maybe?

exocet · Post by **exocet** » Fri Feb 04, 2011 9:08 am

gary sanders wrote:And its only with the overdrive on and PAB off...snubbers maybe?

That's very odd, usually the smaller coupling caps in the OD stage remove bass, mine is certainly lighter in the bass with OD engaged (even if I roll the drive level down to get a 'clean' sound).

Snubbers only remove high frequencies - I guess if you got completely the wrong values fitted there that you could make things sound 'muffled'.

gary sanders · Post by **gary sanders** » Fri Feb 04, 2011 5:22 pm

I had a 270pf on A and a 560 pf on B,changed B to a 330 but not much difference.The only .0047 I had was a 1600V orange drop and I used a .015 in the .01 place.(the 1600V .0047 is huge and looks like a .1).I wouldnt think the .015 would make that much of a difference than a .01.

Its just really muddy overdrive with the bass knob turned up past 3,its bassy on the clean channel but in a good way.If this is just how the ODS sounds I can live with it.Just turn the bass down and it sounds great but its just one of those things that looks strange cause the bass knob is on 2 and very touchy between 2 and 3

How would changing from a 500k to a 250k pot change it?

Structo · Post by **Structo** » Fri Feb 04, 2011 5:56 pm

Do you have the Rock/ Jazz switch?

On my amp in Rock mode, I generally have the treble at 10:00, mid 10:00, and bass at 10-11:00.
The bass really starts kicking in above 11:00.
I notice in Rock mode that the bass is not real tight.

Now this is all at below gig volume since I am just messing around when I'm playing.

But all this doesn't matter if we have different tapers on our pots from the next person.

I find in Jazz mode that I have to turn up the mids and bass but it also seems that the bass is much tighter, more defined on the notes, not as mushy.

67plexi · Post by **67plexi** » Fri Feb 04, 2011 6:13 pm

Gary, The bass pot change is the first place I would go if you can find one a 350k for starters.
I just finished a #183/#204 build tight bass. Used a 317k bass pot but my output transformer
It’s huge. I think it was the bass pot. I can hit the low E string hard no flab on the bass.
Who knows what the bass pot measured out to on the real #124? I don’t.

Steve.

gary sanders · Post by **gary sanders** » Fri Feb 04, 2011 6:48 pm

Will try that.I have a big OT on this one as well.Its for a 4x 6L6 and Im running 2.Thanks for the suggestion,will see what that does

Chris333 · Post by **Chris333** » Fri Feb 04, 2011 7:45 pm

gary sanders wrote:Will try that.I have a big OT on this one as well.Its for a 4x 6L6 and Im running 2.Thanks for the suggestion,will see what that does

My 50W amp started out with a high-power tweed twin OT, and nothing I tried made the amp sound right, although I don't remember ever trying a smaller bass pot. It always had huge, vague-sounding low end. Putting a BF Bassman-style OT in it fixed it. Even with the smaller OT, it sounds best with the bass pot down around 3...

ampdork · Post by **ampdork** » Fri Feb 04, 2011 8:15 pm

Give a cigar to Plexi! If you guys look closely at the layout Tony drew you can see the actual value measured in circuit is 311K (IIRC).

Also the snubbers are 25pF.

The 30uF's may not be helping...

What caps are you using on the output plates? Some disagree but I think the big ass filters make a difference.

I would suggest making changes that brings your amp closer to the actual values before changing a bunch of stuff to alter the bass content.

Good luck.

67plexi · Post by **67plexi** » Fri Feb 04, 2011 11:29 pm

Big Ass Filters Rock.............

talbany · Post by **talbany** » Sat Feb 05, 2011 12:27 am

67plexi wrote:Big Ass Filters Rock.............

DEFINITELY!!

T

ampdork · Post by **ampdork** » Sat Feb 05, 2011 12:59 am

whoops my bad...wrong amp. Disregard my previous comments.

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