The Amp Garage

Do you have 150k resistors to ground from pins 2 and 7 instead of 150 ohm?

Heater voltage was 2.9vac at pin 7 and 6.9 at pin 2 - but 6.2 measured across 2 &7; panel light consistent with this as well. Don't understand this... If pin 2 to pin 7 is 6.2, I would think pins 2 and 7 should both be ~3.1 to ground. Is the only load you have on the heater circuit the panel lamp? ...

My thought was keep the load similar to the Second Gen to preserve its character, and allow some plus/minus on the level coming out of the OD wrt the fixed divider in the Second Gen layout. The main point is, however you do it, the Ratio control provides for adjustment of the OD output without going...

Looks good now.

Stevem wrote: ↑Tue May 14, 2024 11:20 am Thanks for this test out and post, and yes that’s over a 10% different which is a lot!

My math says over 1000% in ESR. A current data sheet from Mouser indicates IC is part of CDE, and the max ESR for 10uF 160V axial at 120 Hz is 33.157 ohms.

Correct. The cap is a bypass around the upper part of the resistive divider.

I finally got a load of caps to try in my 5F1 based amp. Quick question: Do I put the bright cap between lugs 1 and 2 of the Volume pot, or between lugs 2 and 3? I've seen it mentioned both ways. Or doesn't it matter? Might depend on how you number the lugs. If lug 3 is the input, lug 2 is the wipe...

So, I'm just looking at the FET circuit and the Relay power supply. If I use the Triad F-216X 12VAC supply, it looks like I use a FWB rectifier. I need a TO220 Regulator? Any recommendations? It just needs to regulate that 12VDC? LM7812 regulator as shown on the D schematics will be fine. Looking a...

Am I seeing right that I may be able to take my heater supply and use it to feed the power for the relay switching? Or is that generally more trouble than using one of these 12V transformers? I think it's simpler to use a separate transformer for the relays. You can use 12VAC and a bridge, or 6VAC ...

... and trying to figure out what transformer works well for the relay power... Raoul Duke posted a data sheet for this small Triad for relay power using a FWB: https://www.mouser.com/ProductDetail/Triad-Magnetics/F-216X?qs=b1anAsPanWyvCrSmsu4ZQw%3D%3D This Hammond is also a possibility for FWB: ht...

bcmatt wrote: ↑Mon May 13, 2024 4:12 pmRight now I'm looking for that FET level knob mod with relay switching that Martin had drawn somewhere... and trying to figure out what transformer works well for the relay power...

There's info on these in the ODS boards .pdf here https://ampgarage.com/forum/viewtopic.php?f=5&t=29630

I did a bit of that and noticed it cleaned up well. If I can live with it that way and not have to alter the circuit that would be ideal. If not, the dual masters is a good plan. I never run two cabs anyways. The only bit of the circuit you would need to modify is between the OD2 coupling cap and O...

I already have something like this set up on an HX Stomp on my board at the moment, and it does sound great, but we started laughing at the idea of having both loops being tube-driven... And joked that we might as well throw in a tube-driven reverb tank in there too. That's a lot of tubes! 4 preamp...

Yes try changing the bias point. The gain should rise sharply at some point and then level off.

dbharris wrote: ↑Sat May 11, 2024 2:50 pm New FET biased up easy. I set it for just under 3 for the Vdd/Vd ratio. It sounds good, but the volume is lower than the normal channel even with the FET trimmer wide open. I may bring the ratio closer to 2.5 and see if that helps.

What are the voltages at the top and bottom of the drain resistor?