johnsonwu
Responses from johnsonwu
| Does this amp have a problem or is it OK to buy? Humming to the speakers is because the AC filament supply to the 12AU7 is making it into a buzzy microphone.Spent MONTHS on my previously modded 302B to fix the problem by taking out the center tap for the filament which had become intermittent, a... | |
| Could use your advice re: tube gear The Jolida 302 and 502s have wonderfully overbuilt power trannies (output is a different story but still very competent. Lots of space for mods. And a simple enough circuit topology to allow the modder to be flexible with tube choices and current ... | |
| KT120 transformer failures What's with all the posts about TCtubes all of a sudden everywhere on every thread that has to do with tubes? | |
| ARC SP-6 Warmup time Capacitor next to u555 timer ic is shot. Happened to my sp10ii a few years back. | |
| KT120 transformer failures Run the CL120 half power with 4 kt120 each mono block and you can have your kt120s. | |
| Thoughts on Audio Research D70 @DaveyF: great to hear u are in love with your D70 all these years... much like me --> my Counterpoint NP220 Premium Gold. I am surprised that Olsher didnt mention anything about converting it into triode. I was under the impression that he's a... | |
| Thoughts on Audio Research D70 @Hifigeek1: After pulling 8 screen grid Rs and tying pins 3-4 on all 8 power tube sockets and 2 resistors in the bias regulator circuitry (was tuned for pentode mode at 40V I need 49 or so) I got myself an all tube CL60 :)Whether running it as a t... | |
| Anyone heard the Ming Da MC34AB I have an ancient old email from FxBill with the schematic.FxBill doesnt seem to be active on various forums recently.(Miss U Bill!)Let me see if I can dig it up. | |
| Thoughts on Audio Research D70 D115... Becomes a tubefied CL60... | |
| Thoughts on Audio Research D70 Checked all the regulated B+s and they are quiet and stable. No more oscillations.All diff amp balances measure AOK.Gain is too high for my liking so in a sense it's indeed not quiet enough.Maybe a triode mod will give me the extra benefit of lowe... | |
| Thoughts on Audio Research D70 Point well taken, esp with coupling caps where I often choose not to parallel a tiny 0.01 for the sake of coherence. Would rather invest more and get a better single cap.For B+ bypass my experience is YMMV. I noticed that blackgate lytics will sou... | |
| Anyone compared 6922 Sovtek & Electro-Harmonix How about differences between the two triodes in the same tube? I have problems the both Sovtek and EH in this dept. 6922s and 12au7s alike. But heck for the price I can have one in 3 tubes that are sub par and still be ahead. | |
| Thoughts on Audio Research D70 @Hifigeek1: Never mind, the relcap 2.0uF bypassing the cathode (regulated B+) output of the regulator 6550C has deteriorated enough that when I paralleled in another 1uF all is good. Time to replace them bypass Relcaps too I guess. | |
| Thoughts on Audio Research D70 @Hifigeek1: I was trying to do some final checks on the regulated voltages to the first stage B+ and regulated screen grids and I found an ultrasonic oscillation of about 20mV peak to peak. My mistake for not turning the horizontal dial of my scop... | |
| Thoughts on Audio Research D70 @HifiGeek1: Audio Research seems to source caps from The Reliable Cap company (Audio + Rel) and TRT (which some think is sourced from ASC). I will pass on big sized caps for now. Even the 0.47 I have I couldnt find anything to fit them in.@DaveyF:... |