Level pot question

[greiswig]

I feel like I should know this, but...

I'd like to get more overall volume (relative to the clean channel) out of the OD section. It seems like once it's past about 1:00, there isn't any more oomph that can be coaxed out of it. I can think of a couple of ways to do this.

1. I could put a resistor between the ground and the 100kB pot. I wouldn't be able to turn it down all the way, but who wants to do that anyway?

2. I *think* I could just put in a larger-value pot there, but I suspect I don't need a 250k, and I don't have anything but 250kA to try. Should I tinker with paralleling resistors across a 500kB pot outer lugs? Is there something else I need to watch out for on this voltage divider setup and how it interacts with the rest of the circuit?

Thanks!

[heisthl]

Tony (VVT) had a good tip for this on non-HRM amps. Just use a 250k or 500k pot. You get more volume.

[butwhatif]

Sometimes using a 250k or bigger pot will give a too fat a sound, or too much mud, do to the decreased load provided back to the od2 plate. Have you checked the input to od1 trimmer to ground value? It may be set too low and sometimes a small increase can get the results you need.

[greiswig]

Sometimes using a 250k or bigger pot will give a too fat a sound, or too much mud, do to the decreased load provided back to the od2 plate. Have you checked the input to od1 trimmer to ground value? It may be set too low and sometimes a small increase can get the results you need.

Interesting. Yeah, I've checked the trimmer value. With the 100k ratio pot, this amp seems to like the trimmer set right around 30k to ground. Any more, and I don't get additional volume, just more overdrive.

[butwhatif]

I hear what u r saying, and if 30k is swamping the od section then possibly
a change in the supply voltage, plate values or cathode values may give the extra punch.
Also depends on how big the snubbers are, and if there's a treb bleed. Getting the supply voltage up a little to one or both sections should get some extra level.
I think there's also the possibility of an issue with having the trimmer set too high-as it seems to let more bass thru, which then swamps the od sections, robbing them of headroom. I try to use 25k as a ballpark, but each amp is different.

[ayan]

I feel like I should know this, but...

I'd like to get more overall volume (relative to the clean channel) out of the OD section. It seems like once it's past about 1:00, there isn't any more oomph that can be coaxed out of it. I can think of a couple of ways to do this.

1. I could put a resistor between the ground and the 100kB pot. I wouldn't be able to turn it down all the way, but who wants to do that anyway?

2. I *think* I could just put in a larger-value pot there, but I suspect I don't need a 250k, and I don't have anything but 250kA to try. Should I tinker with paralleling resistors across a 500kB pot outer lugs? Is there something else I need to watch out for on this voltage divider setup and how it interacts with the rest of the circuit?

Thanks!

Replace the 150K resistor (before the lead master) at the board with a jumper wire, replace the 100K pot with a 250K pot. You will get the same tone and way more volume available.

Gil

[talbany]

I prefer a 250K OD master/level especially w/ Single coils


Tony VVT

[greiswig]

Gil, thanks for suggesting that. I'd thought about playing with the 150k in front of it, but wasn't sure what effect it'd have, and I was about to experiment with a 100k there.

Talbany, butwhatif, heisthl, thanks much! I'll report back on what I get.

[dogears]

I am a bit confused as to why you have this issue. What are your build values?

In my non HRM amps, I have plenty of volume in OD mode. No need for this stuff.

[greiswig]

I am a bit confused as to why you have this issue. What are your build values?

In my non HRM amps, I have plenty of volume in OD mode. No need for this stuff.

This is on a D'Lite, but it's been converted to 100k/1.5k on V1 and V2. I have something between a BM and standard PI, too, that actually turned out pretty nice. If I have the volume control (Clean master) set at 1:00-2:00, I do have enough volume on OD. But if I set it at 3:00, where I am getting some nice tones that I suspect are artifacts of justbarelygoingintoclipping, the OD master can't seem to keep up.

I've wondered about whether there is something peculiar going on, though...others have said that they can get the clean channel to grind pretty well. When I had the higher plates, I couldn't get it to distort at all (audibly) even dimed. With the lower plates, I'm starting to get some clipping, but it makes me wonder what's different about my build from those others.

[Structo]

I have the higher plates on my D'Lite (220K/150K) on both V1 and V2.

It will distort on the clean channel easily if I have the master lower than the preamp volume.
And even with the two volumes in sync it seem to start clipping when over noon if I dig in.

My OD master seems to be able to keep up volume wise to the clean.
Although I don't play real loud often due to it being a small room and the ringing in my ears.

I have mine pretty much to the changes on the Tweeked layout.

I have the chassis out at this moment because I was trying to kill some low end on the OD.
I'm going to try a 1uf bypass cap on V2b.

Greiswig, do you get much noise on your OD channel? (hum and hiss?)

Mines not too bad but I have been trying things to get it lower.

[greiswig]

It will distort on the clean channel easily if I have the master lower than the preamp volume.
And even with the two volumes in sync it seem to start clipping when over noon if I dig in.

See, mine sure won't, at least not enough for me to hear.

Greiswig, due you get much noise on your OD channel? (hum and hiss?)

No, I'm really happy with noise and hum levels. Did a studio recording of our band awhile back (clips on www.thelucyhammondband.com) and even the studio tech said it was quiet and recorded easily.

[Structo]

I take it you have the relays in it for switching PAB and OD?

Did you do anything special for the OD relay switching?

I recently re-did mine.

I went from a 1/4" jack to a 5 pin DIN jack and plug and used a 6 conductor cable that is shielded and also has a drain wire.

That seemed to help but maybe I am expecting too much because when I say it's a bit noisy, that is with everything up and no playing.
I'm sure tubes play a part in that as well.
I think I have a Chinese select in V2 right now and a Sylvania in V1.

Just scored some Baldwin 6L6GC's for it. They appear to be RCA blackplates.

I put them in last night and biased them at 35ma.
Haven't had a chance to hear them yet because my lovely wife is home today.....

A guy gave me a bunch of these Baldwin tubes. About 20 12ax7's that I think are Raytheon's.
They are used but I'll have to see how they sound.

[talbany]

I have had similar issues with HRM's it wasn't so much the volume but that by the time I ran the OD channel up to the volume I liked it was too much gain for me!!I checked everything over tweaked and tweaked and found nothing wrong with the build...I have also found the higher plates contribute to the added headroom and a touch more low end response, with a darker less slankier top (Dah!!)...The last couple builds I've been working with various voltages to see if I could get it to break a little sooner as well as restore some sparkle and zing to the top end.. The last couple I settled on voltages in the 210-215 area on V1 clean channel...225 in OD.. This helped restore some of the lost sparkle, help the amp break sooner as well as smooth out tone.. (less Gravel)... With the higher plates you don't have to worry about the breakup being buzzy so this made sense to me..With reference to the low plates I think the 190-200 range is fine (with the right tube) and concur with everyone else here on that..Too high a plate voltage on the low plates will send an ice pick through the ears especially in OD hence the need for the treble bleed...The slightly higher voltages on the high plate design should help keep the low end in check enough so going to the 250k or 500 in some cases (maybe not a D-Lite w/6V's) should be fine if you want the OD channel to be louder...More girth.. w/less gain associated.. This is where I am at now and could change.. So far I am happy with the results..

I'm going to try a 1uf bypass cap on V2b.

I don't care for 1 uf's in any D-design.. I think it sounds better w/no bypass cap there instead of a 1uf..JMHO!!



Tony VVT

[Structo]

Wouldn't having no bypass on either of the V2 cathodes kill the gain?

Something else I did this morning was that I noticed that I had missed replacing a coupling cap on V1b.
Originally on the D'Lite it is a .05uf and on the Tweeked layout this is changed to .02uf.
For some reason there was a polypropylene orange drop there so I replaced that with the PS .02uf.
That along with the 1uf bypass on V2b has really changed the tone.

Although I did install the two black plate 6L6GC's so it may be the combination but it finally has that familiar Dumble tone.
I biased a little lower than it had been too, at 35ma.

I may change the bypass cap back to 4.7uf to see how that works.