Found my mistake-I removed the NFB resistor and the neil special simply moves it so that it's in line with the presence pot. I didn't read the fine print so closely.
If you use the Neil Special layout the MV is engaged in both 2203 and 1959, you have to use the first layout on SDM's site to disengage the MV when in 1959.
Didn't have the chance to crank my amp tonight, but I definitely like the mod. Thanks for the help guys.
Link to easy build switchable 1959 to 2203
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sixpakldp
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sixpakldp
- Senior Member
- Posts: 203
- Joined: Thu Feb 26, 2009 12:02 pm
- Just the numbers in order: 7
Re: Link to easy build switchable 1959 to 2203
So been playing my amp with the new mod, only one problem left to solve. When on 2203 mode the amp has a hiss/squeal apparent when you begin to turn up the gain past about 5 or so.
I have shielded wire running from V1 to the control and the shield is grounded to the middle lug of the pot.
Haven't tried anything yet, however going to swap around tubes and move wires with a pencil to see if anything changes. I read some posts about stock 2203's having wires maneuvered into certain spots to avoid this issue and using some type of goop between wires.
Anyway, I'm running the Neil special layout with the exception that I have a DPDT switch in the hi normal channel in lieu of the push-pull pot and my gain knob on the back of the amp in one of the speaker jacks. The first culprit I can think of is I have a long wire from the pot which terminates at the cap and resitor mounted on the switch. Not sure if that would be an issue.
Any advice, let me know.
I have shielded wire running from V1 to the control and the shield is grounded to the middle lug of the pot.
Haven't tried anything yet, however going to swap around tubes and move wires with a pencil to see if anything changes. I read some posts about stock 2203's having wires maneuvered into certain spots to avoid this issue and using some type of goop between wires.
Anyway, I'm running the Neil special layout with the exception that I have a DPDT switch in the hi normal channel in lieu of the push-pull pot and my gain knob on the back of the amp in one of the speaker jacks. The first culprit I can think of is I have a long wire from the pot which terminates at the cap and resitor mounted on the switch. Not sure if that would be an issue.
Any advice, let me know.