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In the Forum: Analog Playback
In the Thread: The LCR RIAA correctors
Post Subject: The Alnic output stage’s driver.Posted by Romy the Cat on: 10/28/2009
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 montepilot wrote: |
| How would modifying preamp affect sonic character other than just providing more gain. What's the advantage? Once such a modification is made are you restricted to using the 6E6P-DR tube only? Will it change the sound of 7721 & 7728 tube? |
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I would not make the comments about “sonic character” in context of Alnic preamp. I do not know exactly what Alnic does in there. I know that 7788 must not be use as it is not a good driver tube. It was tested by myself multiple times and by deferent people to whom I pitched the 7721 as a substitution of 7788. People loved to use 7788 as out driver in phonostages and DACs but 7721 so much beat it as driver.
The 7721 vs. the 6E6P is a very interesting subject. The 7721 is good 4.5W driver the 6E6P is 8.2W driver. Here is the triode strapped 7721 according to Philips.
The 6E6P will have a bit less plate resistance and able to driver more current. Alnic uses out transformer and I think the loading of 6E6P or 7721 shall be managed accordingly by a transformer. The Alnic not is very sensitive to load – against 10K and 20K load it sound like different preamp. If you driver with it a reactive load it become even more problems. So, even I do have an opinion about 7721 vs. the 6E6P but it would be upon many contingencies.
Therefore I would like Mr. Park of Alnic himself to investigate this subject and make the recommendation for his users - it is his game. For him it would be very easy to extend recommendations how to make the 6E6P to sit at 200V and 20mA with the default Alnic regulator. The 6E6P is also is 30 times less expensive then 7721, so Mr. Park shall be motivated.
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