Search found 3077 matches
- Wed May 15, 2024 1:19 am
- Forum: Dumble Discussion
- Topic: The Much Anticipated (?) Bluesmaster Build Thread
- Replies: 51
- Views: 1630
Re: The Much Anticipated (?) Bluesmaster Build Thread
Most likely a bad solder joint, broken wire, or wiring error in the filament string. Easy to locate with your meter. DON'T MEASURE FILAMENT VOLTAGE WITH ONE PROBE CONNECTED TO GROUND! Connect one probe to one of the PT green wires and the other probe to the other green wire. Voltage should be as exp...
- Tue May 14, 2024 6:37 pm
- Forum: Technical Discussion
- Topic: Modded Tremolux
- Replies: 38
- Views: 8005
Re: Modded Tremolux
I would be nervous. It's very common to use two 350V caps in series for the reservoir cap.
- Mon May 13, 2024 3:49 pm
- Forum: Technical Discussion
- Topic: Can I Parallel 2 Mosfets in VVR?
- Replies: 19
- Views: 437
Re: Can I Parallel 2 Mosfets in VVR?
For an 18W amp in an aluminum (not steel!) chassis I'd just bolt to the chassis. Don't forget heatsink grease/paste or one of those fancy silicone pads. For a 50W amp I'd use a real adequate heatsink.
For a larger amp I'd just get an 18W amp.
For a larger amp I'd just get an 18W amp.
- Mon May 13, 2024 1:31 pm
- Forum: Technical Discussion
- Topic: Can I Parallel 2 Mosfets in VVR?
- Replies: 19
- Views: 437
Re: Can I Parallel 2 Mosfets in VVR?
If power handling is a worry and I'm worried about that MosFET, can I just add a second MosFET in parallel? I can't imagine a tube amp needing parallel MOSFETs for VVR. Thes devices are rated for high power/high current with proper heatsink. For example, the NTE2973 that is commonly seen in many VV...
- Mon May 13, 2024 12:57 pm
- Forum: Technical Discussion
- Topic: Modded Tremolux
- Replies: 38
- Views: 8005
Re: Modded Tremolux
My electrolytics are rated for 450V, but with a 5U4, my B+ nears 500V while warming up. Is this okay, or should I get higher rated caps? I would be nervous. I like to measure the AC voltage on pin 4 or 6 of the rectifier tube, multiply that number by 1.414, and chose filter caps with a voltage rati...
- Thu May 09, 2024 5:54 pm
- Forum: Garage Talk
- Topic: Anyone else having issues with the board?
- Replies: 10
- Views: 213
Re: Anyone else having issues with the board?
... and this I what I get when using my new favorites link. This is correct.
- Thu May 09, 2024 5:46 pm
- Forum: Garage Talk
- Topic: Anyone else having issues with the board?
- Replies: 10
- Views: 213
Re: Anyone else having issues with the board?
I can't get "Board index" or "New posts" to show any content. Only "Your Posts" and "Unread posts" work. I've tried deleting cookies, relaunch, restart; no luck. Safari browser. I have a similar issue. My MS Edge favorites link to the forum takes me directly to "Unread posts". About two weeks ago i...
- Tue May 07, 2024 6:08 pm
- Forum: Technical Discussion
- Topic: Modded Tremolux
- Replies: 38
- Views: 8005
Re: Modded Tremolux
That's a very useful frequency range.johnnyreece wrote: ↑Tue May 07, 2024 1:47 pm My range is now (from memory) 2.6-4 Hz on slow, 3.9-9.6 Hz on fast.
- Mon May 06, 2024 11:33 pm
- Forum: Technical Discussion
- Topic: Gibson GA-50 tone stack
- Replies: 16
- Views: 395
Re: Gibson GA-50 tone stack
That's the same schematic I have. All four pots in this snip are connected to ground. The 2.2K cathode resistor is also directly connected to ground. The 2.2K does not have to go through the bass pot to get to ground. Could it have been drawn more clearly? Absolutely. But that's not the Gibson way! ...
- Mon May 06, 2024 10:08 pm
- Forum: Technical Discussion
- Topic: Gibson GA-50 tone stack
- Replies: 16
- Views: 395
Re: Gibson GA-50 tone stack
That's not what my schematics show. That 2.2K is the PI cathode resistor and it connects to ground. Same for the ga50 and ga50T. Has nothing to do with the bass pot.
- Sat May 04, 2024 1:24 pm
- Forum: Technical Discussion
- Topic: Can I use 6v6's in a 69 Super Reverb ?
- Replies: 16
- Views: 420
Re: Can I use 6v6's in a 69 Super Reverb ?
will I need to mod the bias supply and, if so can I still get enough range to be able to return to 6L6 when wanted ? Also what If I connected a 8ohms load ? The SR sets the bias voltage to -52V. The DR sets the bias to -35V. If your bias pot can swing as low as -35V you're OK. Otherwise, a simple m...
- Fri May 03, 2024 4:20 pm
- Forum: Technical Discussion
- Topic: Light bulb limiter tured bright at power on
- Replies: 6
- Views: 219
- Fri May 03, 2024 3:08 am
- Forum: Technical Discussion
- Topic: JTM45 Build, looks alive but no sound,
- Replies: 7
- Views: 260
Re: JTM45 Build, looks alive but no sound,
Lastly, I used the signal generator of an oscilloscope to send a sine wave thru the amp. I connected the scope to the grid of V1A (12ax7) and I get a normal sine wave. I turn on AC coupling and connect the scope to the Plate of VIA, I get a clipped sine wave. (photos attached). The clipped Sine wav...
- Wed May 01, 2024 3:19 pm
- Forum: Technical Discussion
- Topic: What should I build?!?
- Replies: 7
- Views: 248
Re: What should I build?!?
Build something that uses the same output tubes as the donor amp.
- Wed May 01, 2024 12:05 pm
- Forum: Technical Discussion
- Topic: Fender question
- Replies: 10
- Views: 280