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In the Forum: Analog Playback
In the Thread: The last phonocorrector: “End of Life" Phonostage
Post Subject: “End of Life" Phonostage: what is next?Posted by Romy the Cat on: 6/1/2008

OK, here are some follow up thoughts after the completion of the project. I am sure I will burn it for a month or so. I think everything will be fine, I do not expect any issuers technical or sonic. The way how the entrance to the corrector done it is very easy to replace the 4 cable from 4 arms without replacing the cables. As I told I did found a very interesting “second phonostage” (very convent one) that I was planning to use with my other arms but if it is so convent to flip the cable I wonder if I go for the second phonostage. I still have my former 834PT and the 7788-7721 phonostage available, all performing perfectly fine … later on I will decide if I willing to use them.

There is one area that I would like to explore with my “End of Life" Phonostage after it will settle down. The very smart fist stage in there will be stay as is, also I have no interest to experiment with second stage. The last stage is just a cathode follower. In my ultimate buffer experiment I never was able to get a good transparency from tube buffers, so I am intending to put there (as an experiment) a transistor instead the last 12AX7. I am not planning to change anything but juts to take a male 9-pin tube socket, solder in there a transistor that is able to care 300V and juts plug it and play. It is possible that with SS output buffer I might get different result. What kind result I would like to get? Sonically I can’t at this point to identify what I would like to get but measurements –wise I would like to drive the low range to sub 8Hz at 0dB. It is not that my hands are itching but I feel that at line level SS buffer shell do better than a tube…. If someone know any good sounding low power (5-15mA) transistor at 300V-350V then please let me know. So far I was proposed MPSA42, ZTX458 and suitable but too powerful MJE340. As a reader of my site suggested:

“The NPN will reduce the output impedance => will affect the Riaa feedback increasing the gain by ~1db@20Hz and ~0.5db@50Hz (in your setup will be quite noticeable). A quick and dirty remedy is to add a resistor (1k5-1k8) in series with the emitter of the NPN. Although this could be useful to reveal the sonic properties of the NPN it may also defeat the trouble”

I still consider the options how to make the experiment with buffers substation clean and methodologically kosher. Sine I have absolutely no knowledge at SS any recommendation are welcome via the site or direct emails.

Rgs, Romy

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