Search found 178 matches
- Sat Dec 09, 2023 4:59 pm
- Forum: Technical Discussion
- Topic: failed diode / PT question
- Replies: 12
- Views: 3921
Re: failed diode / PT question
I had an older MIG50 in with a blown soviet era bridge rectifier just last month... Not sure sure why they would be more prone to failure than anything else, the B+ is high, but not that high. Probably just a coincidence. I watched a video recently about someone getting counterfeit voltage regulato...
- Sat Dec 09, 2023 2:53 pm
- Forum: Technical Discussion
- Topic: Conjunctive filter
- Replies: 18
- Views: 4000
Re: Conjunctive filter
In RDH4, Smith provides some examples. You might find that helpful in combination with some of the concepts teemuk was explaining.
Here is a screenshot of page 588.
Here is a screenshot of page 588.
- Sat Dec 09, 2023 2:38 pm
- Forum: Technical Discussion
- Topic: failed diode / PT question
- Replies: 12
- Views: 3921
Re: failed diode / PT question
just curious, where did you buy you UF5408s? A few weeks back a customer came in with a newer model Sovtek MIG 50 with a blown mains transformer. Even though it was out of warranty, they replaced the PT, no cost to customer. It turns out that a shorted 1N5408 probably took the transformer out (usual...
- Fri Dec 08, 2023 9:03 pm
- Forum: Technical Discussion
- Topic: Just when I thought I had come to understand OT secondaries,,,
- Replies: 25
- Views: 9444
Re: Just when I thought I had come to understand OT secondaries,,,
like the others, I don't make this measurement using resistance. I use my signal generator and my oscilloscope. It's very safe and very accurate, even applying lower voltages to the primary. My signal generator can output an undistorted 10V p-p sine wave, and my o-scope can list and measure RMS, Pea...
- Thu Jul 20, 2023 3:19 am
- Forum: Technical Discussion
- Topic: Midpot to 50k and a question
- Replies: 11
- Views: 1333
Re: Midpot to 50k and a question
One small change... Instead of saying "yellow/purple/orange", you should say "yellow/violet/orange". Purple is not on the color charts. :mrgreen: My professors in art school, would roll her eyes and correct any one who called it color "purple", and say "there's no such color as purple. You mean 'Vi...
- Sun Jul 09, 2023 10:12 pm
- Forum: Technical Discussion
- Topic: Copel Rotary Switch
- Replies: 2
- Views: 314
Re: Copel Rotary Switch
I don't have any experience with the Copel switch, but last time I looked, pickings were getting really slim for heavy duty rotary switches we can use as impedance selectors. NKK discontinued many of their nice rotary switches a couple of years ago, and they were the diy industry standard and good q...
- Sun Jul 09, 2023 9:45 pm
- Forum: Technical Discussion
- Topic: Calibrating gain stages
- Replies: 7
- Views: 873
Re: Calibrating gain stages
I would just add that how each gain stage is biased makes a huge difference in how the amp sounds, and responds at the beginning of clipping through heavy overdrive (as well as if a particular stage has a cathode bypassed or not). For instance, if you set up you test circuit with trim pots for catho...
- Sat Jun 03, 2023 5:49 am
- Forum: Technical Discussion
- Topic: Help with dropping B+ with Zeners
- Replies: 33
- Views: 2298
Re: Help with dropping B+ with Zeners
I would be surprised if RG doesn't jump in on this topic and express that you can use his zener/mosfet combination (from mosfet follies ver...1?) to great effect for your purposes. It is simple, effective, inexpensive, and I used it in a amp I built incorporating 2 EL84s and 3 12AX7s. For that build...
- Tue Apr 11, 2023 9:37 pm
- Forum: Technical Discussion
- Topic: too much hum
- Replies: 15
- Views: 1727
Re: too much hum
Oh yeah. I shorted the input
- Tue Apr 11, 2023 9:36 pm
- Forum: Technical Discussion
- Topic: USA Vacuum Tube Manufacturing Revival
- Replies: 16
- Views: 1304
- Tue Apr 11, 2023 9:28 pm
- Forum: Technical Discussion
- Topic: too much hum
- Replies: 15
- Views: 1727
Re: too much hum
This manifested itself in a kind of noise that had a very "buzzy" kind of quality In my amp (even with the heater wiring and lead dress being being solid). Did you get this buzz with master on zero? Well, I don't have a traditional master volume on my amp. There is just a single volume, however, wi...
- Tue Apr 11, 2023 1:29 am
- Forum: Technical Discussion
- Topic: too much hum
- Replies: 15
- Views: 1727
Re: too much hum
Without touching on all the potential causes of hum issues, maybe I can help trying to eliminate 2 of them. The first: Easy one, a bad tube can cause noise problems which can sound like a number of different problems. You can start at V1, pulling each tube and listening to whether the tube you pulle...
- Sat Dec 03, 2022 4:55 am
- Forum: Technical Discussion
- Topic: Heater wire supplier
- Replies: 3
- Views: 593
Re: Heater wire supplier
I want to buy by the roll. I'm tired of fighting this. I don't like doing heater wiring and having to search through my rats nest of wire makes it worse. Dude, you're making the right call. You're finally going to be free. I grew so tired and frustrated spending valuable time digging through transf...
- Mon Jun 06, 2022 2:24 pm
- Forum: Technical Discussion
- Topic: NTE resistors
- Replies: 9
- Views: 1185
Re: NTE resistors
They list their 1/2W resistors as metal film. 1,2, & 3W types as Metal Oxide
- Mon Jun 06, 2022 2:19 pm
- Forum: Technical Discussion
- Topic: NTE resistors
- Replies: 9
- Views: 1185
Re: NTE resistors
I think they label those newer ones as flameproof, correct? I think it refers to the coating