Search found 537 matches

by JD0x0
Wed Mar 27, 2024 12:44 pm
Forum: Technical Discussion
Topic: Fryette Power Station
Replies: 16
Views: 477

Re: Fryette Power Station

I don't understand the tube power. I already use tube amps. All loaded, all sub-mixed, effected, and stereo to massive power and sixteen 12s. Slew matters for impact and clarity. The extra tube output is actually anything but transparent at unity. I admit that the device makes me angry. lol For ins...
by JD0x0
Wed Mar 13, 2024 1:12 pm
Forum: Fender Discussion
Topic: Deluxe Reverb power transformer change?
Replies: 11
Views: 518

Re: Deluxe Reverb power transformer change?

This thing wants to run hot. with 120VAC line, the plate V is 455, when tubes are idling 26/30 mA with bias V -50.8V. With the price of tubes throught the roof these days, I'd really like to make them last. Is there a relatively painless way to lower B+ down some? Just use JJ's. Datasheets spec the...
by JD0x0
Wed Mar 06, 2024 2:22 pm
Forum: Technical Discussion
Topic: What do you believe regarding the sound of passive components?
Replies: 185
Views: 4033

Re: What do you believe regarding the sound of passive components?

Here is a pdf and link to various articles and tests regarding different dielectrics vs voltage stress on capacitors. CC are known to have a higher voltage coefficient, and some people point to that and say they will add sweet-sounding second harmonic (thanks, RG), but IMO it's negligible. I tried ...
by JD0x0
Thu Feb 29, 2024 1:22 pm
Forum: Technical Discussion
Topic: What do you believe regarding the sound of passive components?
Replies: 185
Views: 4033

Re: What do you believe regarding the sound of passive components?

This is one of my favorite pics to demonstrate measurable differences exist between different dielectrics. Now, the hard part is quantifying that, and translating to how it will sound in a guitar amp. It's clear that one of these caps is superior if you're going for minimum THD, for something like H...
by JD0x0
Wed Feb 28, 2024 5:29 pm
Forum: Technical Discussion
Topic: Sturdy EL34s?
Replies: 15
Views: 387

Re: Sturdy EL34s?

EL34's should be good to 800VDC on the plates and 500VDC on the screens if they meet datasheet spec (which any decent quality tube should be able to meet.)
by JD0x0
Thu Feb 22, 2024 3:49 pm
Forum: Fender Discussion
Topic: Trey’s Deluxe Reverb mods
Replies: 4
Views: 288

Re: Trey’s Deluxe Reverb mods

The 400VDC coupling caps in the PI are a bad idea. Mesas fail all the time because of this. 630VDC will be better. It's because the -bias voltage is cumulative with the positive plate voltage. The cap 'sees' both these voltages added together. So if we had a -50VDC bias voltage and a 250VDC plate vo...
by JD0x0
Wed Feb 21, 2024 2:46 pm
Forum: Technical Discussion
Topic: LND150 MOSFET as first gain stage
Replies: 21
Views: 541

Re: LND150 MOSFET as first gain stage

Not only do you want the Zeners on the input, but, IMO, you also want a coupling cap on the input to block DC in either direction. This will protect the MOSFET as well as the player, in the event the LND150 shorts, it's possible to get DC from the B+ line on the tip of the input jack.
by JD0x0
Thu Feb 15, 2024 5:10 pm
Forum: Technical Discussion
Topic: New Astron caps?!?
Replies: 22
Views: 701

Re: New Astron caps?!?

Oh yay. More $14-$25 coupling caps that'll definitely sound better than the $0.15 cent films you can get off Mouser :roll: I'd maybe consider using them for repairs if the customer wants to keep the aesthetics, and doesn't mind overpaying for caps. I can't ever see myself doing a build with these, u...
by JD0x0
Wed Feb 07, 2024 1:30 pm
Forum: Dumble Discussion
Topic: CF driver Va - Vk voltages in SSS consensus?
Replies: 76
Views: 3730

Re: CF driver Va - Vk voltages in SSS consensus?

for any output tube cathode follower directly coupled, +150 -100V will be enough blind guess, also mosfet can easily work there But with the MOSFET, you won't get the unique DC coupled CF 'distortion' achievable with the tube. In some cases that may be desirable, but it's worth noting. A note about...
by JD0x0
Wed Jan 31, 2024 3:15 pm
Forum: Technical Discussion
Topic: Orange Drop Capacitors
Replies: 12
Views: 471

Re: Orange Drop Capacitors

some people hear differences some not. That depends on the listener... As you wrote, "its a hard yes or no for one or the other". But that does not mean good or bad over all. To finish the build lgehrig4 can use any suuitable capacitor and it will sound fine. When the types he really like to use ar...
by JD0x0
Wed Jan 31, 2024 3:11 pm
Forum: Technical Discussion
Topic: Orange Drop Capacitors
Replies: 12
Views: 471

Re: Orange Drop Capacitors

Yup, hit up tubes and more for these and don't go buying 600 volt caps for where you don't need then , like preamp tube plates other then the PI output coupling caps. It's good to have the high AC rating of a 600 volt cap there. I'd go 600/630 all around unless the plates run particularly low. We a...
by JD0x0
Thu Dec 21, 2023 12:36 pm
Forum: Dumble Discussion
Topic: "New" 102 ish FET options ...
Replies: 12
Views: 4631

Re: "New" 102 ish FET options ...

I did a high voltage LND150 setup that worked well. I intentionally gave it an EQ curve you'd expect from an OD pedal (shave some highs and lows) rather than a flat response. It works well in place of a pedal in front of the amp, which is a very common setup.
by JD0x0
Wed Dec 20, 2023 1:31 pm
Forum: Fender Discussion
Topic: Harmonic trem in Princeton reverb
Replies: 29
Views: 21518

Re: 2-Tube Harmonic Vibrato

That is a nice trick there Martin! I have absolutely no idea how to implement it in Fender's two tube design though. Here is another way to skin it: Start with the -A, and eliminate the cathode follower. As above, the 10M RA is eliminated by controlling the intensity at the input to the cathodyne s...
by JD0x0
Thu Dec 14, 2023 4:36 pm
Forum: Technical Discussion
Topic: My Champ has a sound problem
Replies: 25
Views: 8912

Re: My Champ has a sound problems

Thank you i understand now. I have added a 220k before pin 7 and replaced the bypass cap switch and feedback resistor. ok it is working like it should i see you want more gain but this is limited topology.. need more tubes for more gain. You can actually get quite a bit of gain/distortion from the ...
by JD0x0
Wed Dec 06, 2023 5:01 pm
Forum: Dumble Files
Topic: 79 Dumble Overdrive Deluxe
Replies: 42
Views: 16463

Re: 79 Dumble Overdrive Deluxe

By the way , what is that seemingly 18-78ohms ( can't figure out the color of the first ring brown ? purple ? ) resistor grounding the entry of the tone stack ( I haven't put it in the scheme yet ) ? What's the point of such a tiny resistor there ? Have I got it somehow wrong on the channels config...