Parallel Loop for a Dumble?

[tictac]

I think this was brought up ages ago. Does anyone use a parallel loop in their ODS type amps, or is everyone using the Dumbleator series loop?

I didn't see anything in the files section, I'd be grateful for a schematic of what you are using...

TT

[Bob-I]

I think this was brought up ages ago. Does anyone use a parallel loop in their ODS type amps, or is everyone using the Dumbleator series loop?

I didn't see anything in the files section, I'd be grateful for a schematic of what you are using...

TT

I actually breadboarded a parallel loop using a CF as a driver and feedback amp as a mixer. I sounded fairly transparent but I've never built it into an amp. I'll look and see if I can find the schem.

[Bob-I]

Here it is

[heisthl]

better add a resistor from grid to ground on the second stage

[Bob-I]

better add a resistor from grid to ground on the second stage

Actually, the connection between the feedback resistor and the 100k from the return is a pseudo ground. I used this schematic from Aiken amps http://aikenamps.com/FeedbackAmp.htm see finished amp. Mine has some changes for frequency response and gain.

[heisthl]

Just for grins stick something between 220k and 1meg to ground on the grid - should liven it up a little.

[Bob-I]

Just for grins stick something between 220k and 1meg to ground on the grid - should liven it up a little.

I did, it kills it. With this in place it sounds liek someone threw a blanket over the speakers.

[heisthl]

I did, it kills it. With this in place it sounds liek someone threw a blanket over the speakers.

That's what you said about Mica caps too....You've got too many blankets at your house

[tictac]

I finally ended up using this, it's a parallel/series loop with bypass but you keep the cathode follower in the circuit at all times. I really like it.

I left the cathode follower in the circuit mainly to keep the leads short and everything on the back panel but you get the noise reduction benefit from the follower as well.

TT

[Bob-I]

I don't understand how the return level works in parallel mode. I seems to be after the mixer so it would control both the levels, the effect and the dry.

[tictac]

True. The wet/dry mix would be set by the send control, the return is more like a master volume which is one of the reasons I like it. The return before the mix stage doesnt give you any control unless you have an effect plugged in. This way you have control of the overall level no matter what mode your in. (except bypass of course)