John Curl's Blowtorch preamplifier part II - Page 2998 - diyAudio
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Old 26th November 2012, 08:08 PM   #29971
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I know that I should not say this, but I am still disappointed in CD's. Even modern ones played on new, SOTA electronics (OPPO 105).
For example, just this month, a recording engineer of the Chicago Symphony Orchestra (CSO Brass) sent me a CD copy from a 24/96 master or an SACD and I really like the music, BUT I don't like the GLARE of the CD. Oh well, yet with the same playback equipment, I love Chesky 24-96 and SACD's. Now I have to get the SACD of the same performance to compare.
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Old 26th November 2012, 08:10 PM   #29972
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You bet! However, it still sounds good. It has both coupling and output transformers, and VERY LITTLE negative feedback. To impress my 19 year old technician, I played it for him a few weeks ago. He was amazed! So much for progress. '-)
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Old 26th November 2012, 08:28 PM   #29973
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Quote:
Originally Posted by PMA View Post
We all know, the Bajazzo! Full of germanium transistors. Does it have coupling transformers as well?
Design was great, like all Telefunken designs, both RF and mechanics. Most probably it used something like AC117 output transistors, similar to ГТ-402 on your picture, but smaller and encased in an aluminium bar with drilled hole for mounting on heatsink.
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Old 26th November 2012, 08:34 PM   #29974
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Quote:
Originally Posted by john curl View Post
You bet! However, it still sounds good. It has both coupling and output transformers, and VERY LITTLE negative feedback. To impress my 19 year old technician, I played it for him a few weeks ago. He was amazed! So much for progress. '-)
They used parallel feedback to the base of the driver, input transistor was loaded on it. Quite unusual for modern designs, "voltage gain" oriented.
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Old 26th November 2012, 08:40 PM   #29975
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Quote:
Originally Posted by Wavebourn View Post
Most probably it used something like AC117 output transistors, similar to ГТ-402 on your picture, but smaller and encased in an aluminium bar with drilled hole for mounting on heatsink.
My first amplifiers were with GC511K/GC521K

Click the image to open in full size.
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Old 26th November 2012, 08:41 PM   #29976
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Please excuse what might be an uninformed question but might not those aberrations you show be exactly what the amps FB demands to keep the o/p cct clean when the o/p devices are switching ?

If the glitches didn't appear in the i/p cct perhaps they would show up on the o/p trace.

Just a thought

mike
Nothing like thoughts, gotta keep the gears movin' somehow ...!

These "investigations" stem from my point that the FB area has to be able to function perhaps at an order of magnitude better than the amp overall, to really do its job. That output waveform is a 20k sine wave, with the FB "glitching" or correcting, at something way beyond that frequency. To me, these are parasitic oscillations, triggered by instability in the amplifier, they shouldn't be there because at the very least they can couple to parts of the circuit that shouldn't see those sort of frequencies.

If enough of the FB circuits out there in the real world are doing this, then maybe that's why this technique has got a bit of a dirty name ...

Frank
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Old 26th November 2012, 08:48 PM   #29977
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Quote:
Originally Posted by john curl View Post
I know that I should not say this, but I am still disappointed in CD's. Even modern ones played on new, SOTA electronics (OPPO 105).
For example, just this month, a recording engineer of the Chicago Symphony Orchestra (CSO Brass) sent me a CD copy from a 24/96 master or an SACD and I really like the music, BUT I don't like the GLARE of the CD.
You've got glare? Sorry, John, but that means you're listening to distortion, pure and simple, of the replay circuitry, you're not hearing what's encoded on the CD. As I've said many times, it is not a trivial exercise to eject that gremlin from a system, which is not the same thing as saying it can't be done ...

Frank
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Old 26th November 2012, 08:52 PM   #29978
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Quote:
Originally Posted by PMA View Post
My first amplifiers were with GC511K/GC521K

Click the image to open in full size.
My first amp used П4ГЭ
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File Type: jpeg p4ge.jpeg (4.8 KB, 103 views)
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Old 26th November 2012, 08:56 PM   #29979
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Except that that reproduce system is SOTA and first class. AND it works for SACD, Blue Ray, and 24/96K just fine. AND I have the schematics and approve of them, (at this price point).
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Old 26th November 2012, 08:57 PM   #29980
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Originally Posted by fas42 View Post
You've got glare? Sorry, John, but that means you're listening to distortion, pure and simple, of the replay circuitry, you're not hearing what's encoded on the CD. As I've said many times, it is not a trivial exercise to eject that gremlin from a system, which is not the same thing as saying it can't be done ...
John, read this, fas42 is RIGHT !
It is pretty difficult to get a perfect digital signal. need very low noise PSUs, separated for Digital and analog, need perfect clocks, need perfect first analog stage etc...
I use a digital filter (Behringer DCX2496) Was obliged to change a lot of parts (psus, clocks , analog stages. It was awful at first sight. Absolutely transparent and fluid now.
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Last edited by Esperado; 26th November 2012 at 09:02 PM.
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