blubliss
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Posts posted by blubliss
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That is beautiful!
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The voltages change a bit , maybe around 10 volts or so on the balance, possibly more on the offset during warm-up. Just adjust to zero at the start, then after an hour. I readjusted to 0 after an hour plus tonight, will check periodically the next few times I run, then leave it alone. I actually think I may be done adjusting already and everything seems to be under 1 volt.
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Listening to music with the 009 and it is quite nice. I know I probably shouldn't use these phones, but...
Switched on the T2 for just a minute, swapped back and forth a few times just for giggles. A T2 it is not, but that makes sense. The sound is richer, thicker than the T2, less refinement I would say. Now this could be great for poor recordings and such. The T2 tone with the tubes I am using just seems more right. It's been on for about 45 mins. and the heat is very low, nice, that is a big plus over the T2 (unless you live in Iceland
). Is there any burn-in for this type of amp?
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Kevin figured it out, I was just the guinea pig
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Pictures of the feedback fix.
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Two working boards now! We replaced all the active parts on the 2nd board and there was still a problem. We finally found that the LED, D1, was bad. Later we'll hook up both boards and maybe have a listening test.
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We crossed the 50k resistors and one board is now working. Very close on balance, millivolts, and about 3v on the offset without much work. Now working on the other board which does have some fried parts due to the 1486 being in backwards before, looks like 2 of the 4686 were done in.
We left in the 1.2k for now since we didn't have the 1350.
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We measured the current, seems fine. There is 2.7v across the 2K resistor, which equals 1.3mA, right? Back to the 1.2K resistor I guess.
So now on to the feedback thing. Seems like crossing the resistors would be easiest.
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Pretty sure i got everything except the IXTP (from mouser) at bdent, so it should be fine.
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I want to see picture of your 2SC2705... and A970, C2240.
Why?
So we also put a 2K in the other amp board, the one where we had replaced all of the active parts and we got the same result as before, pegged at -940. The O +/- WRTG were around -477 and + 480 and the D1 LED was lit.
Did you fire up Horio? We probably have done something stupid so don't use me as an example.
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It actually seems that the flipped transistor did not do any damage but this was with the board where we un-flipped the transistor and did not change the active parts. I guess we should try it on the other one where we changed all the active parts too.
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We put in the 2K resistor and now have balance between O +/-, but now the O +/- WRTG is pegged at ~+480 on both sides, and not adjustable with the offset pot. Also, D1 LED is not lit now.
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Andy just out of curiosity, what were your measured output voltages (+/-) for your HV rails?
Voltages on the PS for the 500v version are around +484 and -477, a bit different, but close.
Also, is there an AC component on the rails?
I will check.
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I hope we have done something else wrong but we can't find it. We replaced all active parts and same problem. I can take pics later today for you. I don't think you will harm anything by turning it on briefly?? If you see 940v, just turn it off right away.
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What doesn't match? From I can see drain is tied to V+, gate is tied to the 1k resistor and source is tied to the 1.2 k resistor, both of which are then tied to the collector of the sc4686, which is what the schematic shows.
Are you looking at the layout, which is correct, or the schematic. I don't know how to read this stuff myself, going by someone else's opinion. It's possible we are wrong.
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Offboard.
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The schematic does not match the board on the IXYS current source, but Kevin thinks the board is right. After we fixed the wrong facing transistor, and proceeded to replace all active parts on one board to make sure that was not the problem, there is still something wrong. When we turn the amp on, the voltage is pegged at -940 (probes in O +/-) and the balance pot will not adjust it. If it is left on more than a few seconds, one of the resistors near the balance pot starts to smoke. We are wondering if there is not a problem with the board, but we can't do any searching since we can't leave it on.
Funny thing about the 1486 being backwards, we could adjust the voltages and get them pretty good, but they fluctuated. But when we had it on with the 1486 the wrong way there was almost no heat.
Anyone have the amp boards working with the IXYS part?
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I'd love to see you guys write some more critical and technical reviews.
we don't require the praise
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I would agree that he is not untruthful but he obviously prefers a woolier presentation witnessed by his previous love for beyers, not liking the HD800, and his sources, mostly NOS types.
To me, I would never take his opinions seriously because my preferences are completely different. I like the HD800.
One thing I liked about his review is that he said the LCD-3 was revealing of bad recordings. This is definitely not positive and I think will turn a lot of people off. I already have plenty of revealing headphones and I go to the LCD-2 for warmth.
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I really like my ECBA/HD800 with the EML300B and a Brimar or RCA Gray Glass 6SN7, more than the KR-PX4. I think Purrin uses the same tube combo as me in his amp with the HD800s?
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I think the duty is around 80%, how could that possibly be rightful?
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I do agree that the 007 is a phenomenal phone, especially on the T2. I could live with it alone, I think
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I've been to some concert halls and I have never heard one that sounded like the LCD-2, which are rich and warm, almost syrupy. A live performance sounds far more like the 009 IME.
Seems like you prefer a more euphonic sound visualperson. Nothing wrong with that.
The bass on the LCD-2 is awesome, I agree, but the 009 is far more accurate, neutral.
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Only if it costs more than $300, anything below that is just plain worthless
Balancing Act
in Headphone Amplification
Posted
If you don't buy them, send them my way