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by martin manning
Sun May 12, 2024 2:01 pm
Forum: Technical Discussion
Topic: Hypothetical Amp Discussion
Replies: 4
Views: 194

Re: Hypothetical Amp Discussion

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...
by martin manning
Sat May 11, 2024 10:05 pm
Forum: Dumble Discussion
Topic: 2nd Gen Build
Replies: 52
Views: 2331

Re: 2nd Gen Build

Yes try changing the bias point. The gain should rise sharply at some point and then level off.
by martin manning
Sat May 11, 2024 3:01 pm
Forum: Dumble Discussion
Topic: 2nd Gen Build
Replies: 52
Views: 2331

Re: 2nd Gen Build

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?
by martin manning
Sat May 11, 2024 1:08 pm
Forum: FAQs
Topic: Tube amp grounding article/info/links
Replies: 26
Views: 80422

Re: Tube amp grounding article/info/links

Thanks Dai.

Moderators, maybe this thread should be moved to the new FAQ area?
by martin manning
Sat May 11, 2024 1:00 pm
Forum: Dumble Discussion
Topic: Robben Ford & His Dumble Overdrive Special
Replies: 13
Views: 353

Re: Robben Ford & His Dumble Overdrive Special

To be fair, the Robben part of the video was a fraction of the overall time. He's talked about his Dumble amps and his introduction to and friendship with HAD many times before, but there always seems to be something new. I agree hearing different players and different guitars was really valuable, a...
by martin manning
Sat May 11, 2024 12:25 pm
Forum: Dumble Discussion
Topic: 2nd Gen Build
Replies: 52
Views: 2331

Re: 2nd Gen Build

If that is just heater glow you are seeing through the hole in the tube base I wouldn't worry about it. Are you seeing that through the gap between the index pin and the socket? Might the odor be transformer varnish?
by martin manning
Fri May 10, 2024 10:37 pm
Forum: Dumble Discussion
Topic: The Much Anticipated (?) Bluesmaster Build Thread
Replies: 42
Views: 1402

Re: The Much Anticipated (?) Bluesmaster Build Thread

I was trying to come up with a rationale, but in the end at 120V the current limit will be the same, Bulb Wattage/120
by martin manning
Fri May 10, 2024 10:18 pm
Forum: Dumble Discussion
Topic: The Much Anticipated (?) Bluesmaster Build Thread
Replies: 42
Views: 1402

Re: The Much Anticipated (?) Bluesmaster Build Thread

I usually plug the limiter into the Variac, but I'm not sure that it matters.
by martin manning
Fri May 10, 2024 8:59 pm
Forum: Dumble Discussion
Topic: The Much Anticipated (?) Bluesmaster Build Thread
Replies: 42
Views: 1402

Re: The Much Anticipated (?) Bluesmaster Build Thread

A Variac and a bulb limiter is the best arrangement.
by martin manning
Fri May 10, 2024 8:53 pm
Forum: Dumble Discussion
Topic: My take on a 2nd Gen ODS
Replies: 89
Views: 2694

Re: My take on a 2nd Gen ODS

The relay spec should be fine. More likely some wiring error, but you say “sometimes” cuts out, which sounds like a faulty switch or relay.
by martin manning
Fri May 10, 2024 6:42 pm
Forum: Dumble Discussion
Topic: My take on a 2nd Gen ODS
Replies: 89
Views: 2694

Re: My take on a 2nd Gen ODS

I worked on it some more last night but forgot to write the voltages down. From testing things earlier everything seemed ok, just a tad lower than what is on the layout and schematics since I had my variac running at ~115VAC to get the heaters right at 3.15VAC on both sides. I was thinking verify t...
by martin manning
Fri May 10, 2024 5:14 pm
Forum: Dumble Discussion
Topic: Robben Ford & His Dumble Overdrive Special
Replies: 13
Views: 353

Re: Robben Ford & His Dumble Overdrive Special

What a great interview! Nice of them to zoom in on the SN stamp ;^), and this has to be the gold standard 102 sound sample.

Thanks for posting!
by martin manning
Fri May 10, 2024 11:00 am
Forum: Dumble Discussion
Topic: My take on a 2nd Gen ODS
Replies: 89
Views: 2694

Re: My take on a 2nd Gen ODS

I was about to say that to keep the 2nd gen's loading on the OD output, delete the 180k to ground and the 1Meg series resistor and go straight into a 250k pot for the added Ratio control. ...Should I pull the 180K and 1Meg resistor as the amp is now or is that for when it has been changed to the hy...
by martin manning
Fri May 10, 2024 10:09 am
Forum: Garage Talk
Topic: Anyone else having issues with the board?
Replies: 10
Views: 201

Re: Anyone else having issues with the board?

erwin_ve wrote: Fri May 10, 2024 10:08 amStrange thing it happened to my mobile as well.
Same here.