Search found 406 matches
- Tue May 14, 2024 3:30 pm
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
Thanks, Martin. Bear with me for a minute because I'm just a tax lawyer and the theory and math side of EE is not my strong suit. I think what Martin is suggesting would be to add a typical 4th/5th Gen ratio control. In all of the Dumble designs I am familiar with there is a series resistor there (i...
- Tue May 14, 2024 1:53 am
- Forum: Dumble Discussion
- Topic: Robben Ford & His Dumble Overdrive Special
- Replies: 15
- Views: 530
Re: Robben Ford & His Dumble Overdrive Special
Here is a video of him playing the amp live back in 1988. I believe that is his dumbleator sitting on top of it. I noticed the amp did sounded a little darker here with the dumbleator. It still sounds amazing!! I wonder if the ageing of the components over time also changed the sound of the amp. ht...
- Sun May 12, 2024 7:12 pm
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
FET is sorted and sounds good. At some point in testing yesterday, I realized my standby switch was wired incorrectly (essentially like there was no switch in circuit). I easily found the mistake, but for the life of me could not see where the OT CT, choke, and standby were supposed to be tied toge...
- Sun May 12, 2024 7:09 pm
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
FET is sorted and sounds good. At some point in testing yesterday, I realized my standby switch was wired incorrectly (essentially like there was no switch in circuit). I easily found the mistake, but for the life of me could not see where the OT CT, choke, and standby were supposed to be tied toge...
- Sun May 12, 2024 6:57 pm
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
I had to pull it and replace with an NTE 452. The J201 wouldn't bias, I think the drain resistor probably needed to be adjusted too. At least for that J201.Stephen1966 wrote: ↑Sun May 12, 2024 1:06 pm How is that J201 sounding? Does it or the circuit do anything to raise the sound floor?
-Dan
- Sun May 12, 2024 11:45 am
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
FET is sorted and sounds good. At some point in testing yesterday, I realized my standby switch was wired incorrectly (essentially like there was no switch in circuit). I easily found the mistake, but for the life of me could not see where the OT CT, choke, and standby were supposed to be tied toget...
- Sat May 11, 2024 5:14 pm
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
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? ...
- Sat May 11, 2024 2:50 pm
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
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. I played the amp for a bit just to get a feel. It sounds very nice. ...
- Sat May 11, 2024 1:08 pm
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
Hi Martin, I think you are correct and it is just varnish. This PT is old and looks a little funky. After I swapped in the JJs, there was still an odor. It seemed like a lot less strong, but at this point my mind may be playing tricks on me. Also, I could not get this J201 to bias in range. It wante...
- Sat May 11, 2024 11:54 am
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
Thanks guys. I'll leave the bias resistor alone for now. The other tube biased lower maybe around 55-57%. I pulled the tubes, sprayed compressed air, cleaned the sockets with deoxit and a toothbrush, looked for any leads that may be close and causing arcing, cleaned the female side of the socket, an...
- Sat May 11, 2024 11:40 am
- Forum: Dumble Discussion
- Topic: Robben Ford & His Dumble Overdrive Special
- Replies: 15
- Views: 530
Re: Robben Ford & His Dumble Overdrive Special
Very cool, thanks for sharing!
- Fri May 10, 2024 10:32 pm
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
Preamp glass for now. V1 and V2 are RCA grey plate 12AX7A. V3 is RCA black plate 12AT7. PXL_20240510_164414227.jpg Power tubes are fender branded Sylvania short bottle 6L6GC with double top getters. PXL_20240510_164448700.jpg When I swapped the tubes I noted 2 things. First, with the bias set most n...
- Fri May 10, 2024 10:22 pm
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
All good with the smoke test and forming the caps. Put my startup tubes in and biased the amp. All functions are working. Tone stack is not super effective, but I think that is just the design. Reserving tone impressions as I only played briefly and at low volume. But does strike me as more raw sou...
- Fri May 10, 2024 10:54 am
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 10
- Views: 270
Re: A SSS Build
Looks great!
- Fri May 10, 2024 10:51 am
- Forum: Dumble Discussion
- Topic: 2nd Gen Build
- Replies: 57
- Views: 2584
Re: 2nd Gen Build
Thank you! I have not used the Jupiter caps before. As the Spragues get harder to find in stock and always more expensive, these seemed like they might be a good alternative.
Orange and blue for my Florida Gators!
-Dan
Orange and blue for my Florida Gators!
-Dan