The Amp Garage

I've never been able to warm up to the standard FET input because of what the low input impedance does to my guitar. :D Hi odourboy, I've attached a picture of the data sheet of the 4th generation Dumble ODS combo amps (source: http://www.roblivesey.com/dumble/). Are you sure that the FET input is ...

Say what was the deal with biasing the JFET on this board? Was it the 8K2 resistor that needs to be adjusted for the bias? Anybody remember how that works or what the proper voltage is there? The trimmer is for input gain right? You can leave the 8k2 resistor as it is, and change the source resisto...

dave g wrote:FWIW, my current favorite setup is non-HRM skyline with 100k/1.5k on CL1 and CL2, and 220k/150k on OD1 and OD2.

Yeah! Me too. I use it in both Hrm and non-hrm.
Works great with strat on both Od and clean. Od best with Les paul, cleans a little wet on LP.

Frank.

brewdude wrote:Have any of you tried a 1uF film cap in the presence?

I tried a Panasonic 1uF/100V film there and I like it, so far.

I must get me some different caps and try
out the difference.
Seems like I`ll never get the amp into the cabinet. ha ha.
:)

Frank

Solved the clean volume problem yesterday. After almost replacing everything in the preamp, the difference between OD and clean became right when I changed the presence cap. ( same value 0.1). Odd! Must have been a bad cap. The amp now sounds sweet. Frank. You said the cap was .1 Is it the .1 cap t...

Yes they can be finicky. What works for one doesn't always work for another. I will say I experimented with different presence caps and FB resistors I agree that it can really make or break that part of the circuit. The tolerances on small value caps like that are all over the place. I tried one th...

That is odd. Why would it care what channel you were on? Very strange! Cause the presence is part of the Power section. How could that affect the cleans, and not the OD. One thing then, the OD sounds much different after the issue fixed. Less fizz, less drive, and tighter. Hm! Tube amps seems to be...

Solved the clean volume problem yesterday.
After almost replacing everything in the preamp, the difference between OD and clean became right when I changed the presence cap. ( same value 0.1). Odd!
Must have been a bad cap.
The amp now sounds sweet.

Frank.

Why don`t someone ask Robben Ford about his amplifiers, instead of this maybe research.
Or is he hard to reach!
Frank.

Finally the relays work fine.
14.5 Vdc into the regulator. 12Vdc steady on the relays.
Did rewire the rectifier board.
The first one was a doubler.

Thank you guys for helping.

Still one problem left. Clean volum??

Frank.

Sounds strange. The OD channel is just an extension of the clean channel. How can the OD be OK but not the Clean? Yes I know. Seems strange. I have been thinking that the od will in some way change the input impedance, cause the fet is also loud even with the trim volume set very low. Hm. Gives me ...

Love that blue... I delivered a matched pair of these earilier this year. Must be Blue Year... [img:1200:654]http://www.glaswerks.com/images/gm1.jpg[/img] Ah! Nice! I have watched your builds. Seems like you have a nice combination of both worlds there. 80`s and 90`s. I´m struggling with this amp. ...

mad_dog wrote:Very nice I was actually thinking about doing something very similar to match my strat.
BTW where did you get the tolex??

Bought it in a store nearby here in Norway.
It was a leftover, but just enough for this build.
:)

F.

It sounds like you are using a voltage doubler rectifier setup with that tranny. Why did you do that? You could use a bridge and a 12v regulator and probably be fine and not have to worry about the excess heat. I used the 124 layout, and was hoping to get a 6v tranny, but seems like I need to rewir...

I just found a transformator jused by alesis for their micro serie effects. The tranny reads 11,2 Vac. I have a 12 volt regulator in my ODS. The DCV reads 29,5 v from the rectified board to the regulator. Will this be to much voltage to handle for the regulator? The regulator is the same ceriatone u...