Nigel and dvv please take note: The 1510 from THAT looks better than any IC based design or hybrid, put up here, so far, and it is CHEAP! (enough to consider) I will love to try it in a JC-3. That would be my ultimate listening test choice, yours would be something different.
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I note that a company selling $10K headphone amps used some of my recordings as demo material this past weekend. I use THAT1512 as the heart of the preamp. I would love to have had tubes, but I admit that the 1512 outdoes my best efforts. If you can beat it, I'm buyin'. 😀
What and you not only paticipated in, but allowed them to get away with "boutique" tactics ..
.....
.....
I wouldn't spend that on a headphone amp, but then again, I hardly ever use headphones except for location sound checks.
The humorous thing was that my amp/pre were hooked up with megabuck cables and line cords. The guy sharing the room with us was just appalled by the 99 cent cords from Apex Jr that Pete Millett was using and the similar cords from Halted that I was using. He did not complain about our keg of Live Oak beer.
The humorous thing was that my amp/pre were hooked up with megabuck cables and line cords. The guy sharing the room with us was just appalled by the 99 cent cords from Apex Jr that Pete Millett was using and the similar cords from Halted that I was using. He did not complain about our keg of Live Oak beer.
If you haven't seen it here is THAT's AES presentation packed with good stuff. This should have been referenced in my article, (slide 44 😉 , winks as good as a nudge to a blind man).
http://www.thatcorp.com/datashts/AES129_Designing_Mic_Preamps.pdf
I'd also recommend their Analog Secrets presentations, though I don't think they plugged you in those. 😀
THAT 1510
http://www.thatcorp.com/datashts/THAT_1510-1512_Datasheet.pdf
I know a similar chip SSM2019 which if memory serves me correctly was used in the Lehmann Black Cube phono stage ?
I have been told these are good also
THAT Corporation 300-series Low-Noise Matched Transistor Array ICs
http://www.thatcorp.com/datashts/THAT_1510-1512_Datasheet.pdf
I know a similar chip SSM2019 which if memory serves me correctly was used in the Lehmann Black Cube phono stage ?
I have been told these are good also
THAT Corporation 300-series Low-Noise Matched Transistor Array ICs
That is a nice article.
The circuit attributed to Birt on page 58 appears at least as early as 1987 in Steve Dove's Consoles article in Ballou's Handbook for Sound Engineers, ISBN 0672219832, and may be in the earlier series of magazine articles of Steve's that his chapter apparently recapitulates (I don't have the magazine series). I have forgotten the name of the person that Steve worked with in the UK who also claims he invented it [= ; there was an exchange sans Steve in the smaller breakaway-from-diyaudio forum some years ago about priority.
It's a nice idea and works of course, but my experience is it's a bit tricky to compensate.
Brad
I am particularly amused by the Birt circuit. When CMU was doing work on speech recognition they had one of the faculty build an A/D converter using the then in sampling availability Sony A/D chip. The finished version was built in a copper case using all the techniques he knew. When it was done it only worked at 12 bits of resolution. I was asked to build one for them. The mic preamp circuit I used was the same! I also did a special power supply (But no where near as good as what I can do today.) I managed to get 14 1/2 bits of resolution, not the 16 the chip claimed. Still don't know if it was me or the chip. They didn't care as the software worked the same on 12 or 14 bits. So all that proved was 12 bits was enough.
I built three units for them. Then a grad went into business offering copies of it!
That was the late 70's as I recall.
I did not think anything in the unit was particularly new or ground breaking.
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Hot ding!
This really looks good - perhaps even a dream come true. ESPECIALLY the two+two matched NPN+PNP, that's practically the whole front end of a fully complementary power amp (with some additional work).
One can even use a four trannie chip for a cascoded front end.
To be honest, I had never even heard of this company until a few minutes ago, here.
THAT makes some cool stuff. Notice the matching is not as close as you can do by hand. For production work though, what a way to go. Be careful of the voltage ratings.
I think that we should add a discrete output stage to the 1510, and it would be even 'better'.
I like the THAT parts. By the way I was told that any of those arrays has the entire complement of transistors inside, and that it is just a package pin count limitation that prevents access to all of them.
I wish they could manage higher beta and lower rbb' though. I was also told that they experimented with higher beta, but the breakdown voltages became too difficult to control.
I wish they could manage higher beta and lower rbb' though. I was also told that they experimented with higher beta, but the breakdown voltages became too difficult to control.
"Better" in what way? As it is, the distortion, noise, and CMR are superb. It has no trouble driving loads, and any crossover distortion is buried. They make another chip, the 1570, which will take the output from a 1510/1512 and drive balanced lines.
I always try for something 'better'. I am not comfortable with a Class B output stage, for my best efforts.
What makes you say it's class B? More likely AB. Distortion residual is damn hard to see, but doesn't seem to be crossover.
And if it works, and works well (I can assure you it does, I'm VERY picky about my recording equipment), and is not limited by the output stage, I'm having trouble understanding the objection.
And if it works, and works well (I can assure you it does, I'm VERY picky about my recording equipment), and is not limited by the output stage, I'm having trouble understanding the objection.
the less than generous conclusion is that someone can't design PS to keep Class B half-wave rectified currents from contaminating the signal path - Class A relaxes PSRR, common impedance, mutual inductance PS current coupling issues
but Class A bias with a few mA current sink on the 1510 output and a buffer for line driving would remove most potential objections
hard to do better with feedback R internal to chip
but Class A bias with a few mA current sink on the 1510 output and a buffer for line driving would remove most potential objections
hard to do better with feedback R internal to chip
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