too much gain

danotron · Post by **danotron** » Tue Feb 10, 2009 7:39 pm

I am working on tweaking my ODS. I find that the Drive control in my OD section does not have much effect....the drive just seems like it is always on full. When I turn up the drive it gets very saturated and bad sounding. I can solve most of this problem by tuning the trimmer way down. But the Drive will still saturate to maximum very quickly.

Any suggestions on solving this would be welcome....

Here is my cct....

heisthl · Post by **heisthl** » Tue Feb 10, 2009 9:31 pm

There must be a build error somewhere - I've built several using almost the exact values you have and have never had that issue.

Bob-I · Post by **Bob-I** » Tue Feb 10, 2009 11:34 pm

Sounds like your drive pot isn't working properly. I'd check it out, if it shows ok, then it may be a bad ground.

danotron · Post by **danotron** » Wed Feb 11, 2009 12:28 am

The pot works. It just seems like it is clipping pretty hard at the lowest setting and can't really clip a hole lot more as I turn it up.

dobbhill · Post by **dobbhill** » Wed Feb 11, 2009 12:49 am

Check ground on drive pot ??
D

Structo · Post by **Structo** » Wed Feb 11, 2009 12:52 am

Do you have the relays installed in this amp?

Something is amiss.

If I back down the drive control to nothing while in OD mode, it will silence the amp.

Where do you have the trimmer set? Measure the wiper to ground.

Bob-I · Post by **Bob-I** » Wed Feb 11, 2009 12:54 am

danotron wrote:The pot works. It just seems like it is clipping pretty hard at the lowest setting and can't really clip a hole lot more as I turn it up.

At the lowest setting the amp should be silenced. I'd check the ground.

danotron · Post by **danotron** » Wed Feb 11, 2009 2:12 am

Sorry guys...it is silenced at the lowest setting but if I crack it a hair, it is already clipping allot......when I increase the pot it clips more but not much.

I just checked the ground and it is ok. From wiper to ground on trimmer is 28k.

Tripple checked the wiring and it's ok

danotron · Post by **danotron** » Wed Feb 11, 2009 2:28 am

Here's a pic......sorry it looks like a dog breakfast...I've been tweaking alot

heisthl · Post by **heisthl** » Wed Feb 11, 2009 2:38 am

I can't tell if the OD entrance trimmer is grounded in the picture.

benoit · Post by **benoit** » Wed Feb 11, 2009 2:42 am

Could this be a problem with the taper on the drive pot?

danotron · Post by **danotron** » Wed Feb 11, 2009 3:13 am

heisthl wrote:I can't tell if the OD entrance trimmer is grounded in the picture.

It is grounded under the board.

danotron · Post by **danotron** » Wed Feb 11, 2009 3:24 am

benoit wrote:Could this be a problem with the taper on the drive pot?

It is linear.

http://ca.mouser.com/catalog/637/676.pdf

mouser part: 313-1601F-250K

heisthl · Post by **heisthl** » Wed Feb 11, 2009 3:26 am

you will definitly like an audio taper better as a drive control.

odourboy · Post by **odourboy** » Wed Feb 11, 2009 5:56 am

I'll second (or third) that. Further, your schematic indicates a 100KB pot and your post says you've gone with a 250KB pot. 100KA is the way to go IMHO.

I see you are in Cambridge. I'm in Port Credit. Not far if you ever want to hook up!

OB

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