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Head-Fi - Bijou All Tube Futterman Headphone Amplifier
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Quote: Originally Posted by SBoy I've read through 140+ pages before coming to a conclusion to DIY this amp. I have some questions though. 1) Can I use CAT5 cable for all my internal wiring except for the signal cable? 2) Some of you said something about bleed the high voltage cap. Does it mean run a resistor across the Caps'…
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Yes. It is not the normal type of NFB, however. This feedback compensates for the fact that the cathode of the upper triode is moving with the O/P signal while the cathode of the lower triode is at a constant voltage (ground). C1 feeds back the O/P signal to the phase splitter where it appears immediately at the cathode of the splitter and where it adds itself to the…
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Interesting question. Signal goes from the output to the junction of R5 and R6 which means it goes from + to -.
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Interesting you should ask this. My proto PTP Bijou does exactly what you want to do. The input stages are in one tube and the phase splitters in another. I don't think this generates any significant crosstalk and is a much easier way to do the PTP.
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LOL. It happens. These voltages mean that you're going to need regal's mod to get a more lush sound from the amp. The 6bq7 plate voltage is ok. I wouldn't sweat it too much, particularly if you're planning to make the mod. But, as you say, to get to 98V you'll need slightly more than 2k. Maybe 2k4 would do the trick.
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Thanks. If these voltages are correct, this would indicate why the 6bq7s sound a little tinny. Pin 6 is at 122V which is 20V too high for the operating point of the first stage. But the worst measurement is Pin 1 at 249V. This says that the plate of the phase splitter is the same as the B+ which means that, basically, no current is flowing in the phase splitter. The…
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Quote: Originally Posted by whitelabrat I've noticed my build is a bit sensitive to mains power junk. I suspect it's comming from the heater supply so I have a couple tricks up my sleeve I'd like to try. This amp will end up in my office where the mains is very noisy due to many industrial influences, so I'm going to need some…
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You know, I would have a hard time with this. The liquid beauty of the Bijou is very real, but the SOHA II has some really nice qualities and I like it alot with the right tubes (right tubes for my ears). The first time my wife heard the SOHA II playing Alison Krause she started to tear up at the quality of the sound without any prompting from me. Once again, I don't…
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Oh I see. I have thought that the next evolution of the Bijou should be OCL as well as OTL. But, as you saw in the earilier conversations, that's not easy in terms of protecting the headphones. Most of the work there is not figuring out the OCL output stage, but figuring out the protection circuitry. That's what will take some time.
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Who knows what the super Bijou will be. And since I am buried in the CTH and Stat amps right now (with another project in the background), if you want to hear a Bijou it might be good to build the current one. A super Bijou might be a ways off.