Search found 13106 matches
- Thu Apr 18, 2024 2:51 pm
- Forum: Technical Discussion
- Topic: Taming amp gain in single channel deluxe reverb build
- Replies: 37
- Views: 606
Re: Taming amp gain in single channel deluxe reverb build
In reference to Martin’s suggestion of the single 100k to ground, wouldn’t that actually increase the gain from what I have now? The 47k and 330k are both parallel to ground, or does the 220k between them affect how they interact? Sorry, I misunderstood what you had in there. In the first schematic...
- Thu Apr 18, 2024 12:30 pm
- Forum: Dumble Discussion
- Topic: Bluesmaster HRM question:
- Replies: 39
- Views: 1297
Re: Bluesmaster HRM question:
Mojo's (likely made by Heyboer) Plexi/800 OT is 3k7 Zpri, and that will make little difference vs. the Bassman OT's 4k. The specific details of its construction (winding pattern) are probably more important. Hammond's JCM800 replacement is 3k2, and I would not go there with 6L6's. A JTM45 OT, even a...
- Thu Apr 18, 2024 11:35 am
- Forum: Technical Discussion
- Topic: Taming amp gain in single channel deluxe reverb build
- Replies: 37
- Views: 606
Re: Taming amp gain in single channel deluxe reverb build
I just finished the initial build of a single channel deluxe reverb, sans tremolo. I'm using a classictone 40-18019 PT and the OT from a Hammond AO35.... The amp sounds fantastic up to 4-5 on the volume and it gets pretty hairy after that. By 6-7 the whole thing starts to really fall apart. It soun...
- Wed Apr 17, 2024 8:49 pm
- Forum: Dumble Discussion
- Topic: Bluesmaster HRM question:
- Replies: 39
- Views: 1297
Re: Bluesmaster HRM question:
I see the 5k1s on the power tubes at grid 1 are soldered directly to the leads heading back to the main board (like an old Marshall or Vox). This looks simple enough, but just wanted to check as to the correct mechanical connection before soldering. Is this a “J” hook situation or is there another ...
- Wed Apr 17, 2024 1:04 pm
- Forum: Dumble Discussion
- Topic: Tweedle Dee on Carter
- Replies: 33
- Views: 997
Re: Tweedle Dee on Carter
5Y3 rectifier will make a big difference too.Stephen1966 wrote: ↑Wed Apr 17, 2024 12:48 pmI'm also thinking that the voltages in this amp are not going to be as high as in the first Tweedle Dee, stock transformers and only three filter stages with a stock (value) 250 Ohm bias resistor on the power tubes.
- Wed Apr 17, 2024 1:00 pm
- Forum: Dumble Files
- Topic: SSS Step filters - Here's what I think
- Replies: 22
- Views: 13608
Re: SSS Step filters - Here's what I think
To be strictly correct in eliminating position 1 you would do this:
- Wed Apr 17, 2024 12:06 pm
- Forum: Technical Discussion
- Topic: Taming amp gain in single channel deluxe reverb build
- Replies: 37
- Views: 606
Re: Taming amp gain in single channel deluxe reverb build
I'm having trouble following you. Maybe refer to the TP (test point) number where you are measuring? What is "PT"?
- Wed Apr 17, 2024 11:04 am
- Forum: Dumble Files
- Topic: SSS Step filters - Here's what I think
- Replies: 22
- Views: 13608
Re: SSS Step filters - Here's what I think
Good to hear you are happy with the result! Yes I have made some small adjustments re the schematic at the top of this thread. What you posted just above is the latest. There are a couple of ways you could do six positions, one would be to recalculate all of the resistor values to keep the "taper," ...
- Tue Apr 16, 2024 10:57 pm
- Forum: Dumble Discussion
- Topic: Tweedle Dee on Carter
- Replies: 33
- Views: 997
Re: Tweedle Dee on Carter
One example of a Tweedle Dee has been documented already thanks to CW, but I suppose there might be some interesting evolutionary changes in this later example.
- Tue Apr 16, 2024 4:19 pm
- Forum: Technical Discussion
- Topic: Output Transformer formula?
- Replies: 11
- Views: 322
Re: Output Transformer formula?
Take a look at the free .pdf download Phil S posted to see if you really want a hard copy. You can get virtually any tube data sheet from https://frank.pocnet.net, and that is what most of the 750 pages of RC-30 contain, and in an abbreviated format. The remaining 200 pages cover circuit theory and ...
- Tue Apr 16, 2024 10:00 am
- Forum: Dumble Discussion
- Topic: Eq's in Dumble 50w out of
- Replies: 11
- Views: 315
Re: Eq's in Dumble 50w out of
Maybe a failed R/J switch that is not closing in Rock setting, resulting in PAB? Measure resistance across switch pins.
- Mon Apr 15, 2024 2:41 pm
- Forum: Technical Discussion
- Topic: Output Transformer formula?
- Replies: 11
- Views: 322
Re: Output Transformer formula?
Is this formula legit? (B+ voltage squared)/(Plate dissipation x number of power tubes) Example: a 50w (6L6GC x 2) build using a known PT and circuit that consistently produces a B+ of ~455vdc- 455x455 = 207,025 35 x 2 = 70 207,025 / 70 = 2,957.5; So the correct primary impedance would be around 3k...
- Sun Apr 14, 2024 1:46 pm
- Forum: Technical Discussion
- Topic: Impedence Selector Circuit Help
- Replies: 4
- Views: 102
Re: Impedence Selector Circuit Help
The wire from the 16 ohm tap back to the main board is the negative feedback, so keep that on the 16 ohm OT tap. If all you want is 4 and 16 ohm outputs, you could just use two speaker jacks, one on the 4 ohm and one on the 16 tap, and eliminate the selector. I would use a switching jack for both, a...
- Sun Apr 14, 2024 1:12 pm
- Forum: Technical Discussion
- Topic: Regarding the B+mosfet reducer and power ground
- Replies: 10
- Views: 271
Re: Regarding the B+mosfet reducer and power ground
...I want the filtercaps to have a reduced differential voltage (that is the sole goal) but, I don't necessarily want the bias voltage scheme to change too widely. So yes, it would make some sense that moving the bias ground with the HT CT to the B+reducer makes sense but, not the filter cap cathod...
- Sat Apr 13, 2024 5:06 pm
- Forum: Technical Discussion
- Topic: Regarding the B+mosfet reducer and power ground
- Replies: 10
- Views: 271
Re: Regarding the B+mosfet reducer and power ground
A MOSFET reducer, just like a zener in the same position, just places the high voltage CT one zener-voltage below the negative end of the first filter cap. As long as nothing else is connected and referenced to the CT, this all works fine, as the high voltage winding is galvanically isolated, and w...