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-   -   Morgan Jones 5842 RIAA (http://www.diyaudio.com/forums/tubes-valves/141657-morgan-jones-5842-riaa.html)

rknize 2nd April 2009 09:34 PM

Morgan Jones 5842 RIAA
 
Has anyone built this thing (or anything like it)? It seems that I already have the bottles needed to build it with his favorite series heater scheme, but the design is complex compared to other RIAA stages out there.

Any thoughts?

Russ

dshortt9 3rd April 2009 08:15 AM

IMHO there is a limit to the THD/noise of the average record. Other than the few really well recorded vinyl records available do you really need the UBERALLESRIAAPRE? A good 6DJ8 is all that is needed for 95% of all records available. Go with the 5842 for the ultimate RIAA Pre but it will be the last you ever need.

rknize 3rd April 2009 01:54 PM

Thanks. I get that feeling as well. The parts count is high due to his very thorough power filtering between each stage. He does also discuss a "practical" RIAA stage using 6DJ8s and CCS plate loads. I recently went through some of my tube stash and was reminded of his 5842 design. I am also considering an Aikido RIAA stage, since it involves a PCB and thus it is highly likely that I will actually finish it.

At some point I need to build something...

Russ

theoldtrout 3rd April 2009 09:29 PM

I agree the MJ RIAA is heavy on components. I'm putting together a version of the Phonodude RIAA stage as a try-out, this has very few parts and apparently sounds very good. Do a search on this forum.

kevinkr 3rd April 2009 10:50 PM

I use the D3A and 5842 in my current phono stage design, and all I can say is it is absolutely silent, and a phono stage can never really be too quiet. It was worth the trouble and sounds like it..

SY 4th April 2009 12:05 AM

Quote:

a phono stage can never really be too quiet.
Couldn't agree more. What Morgan also paid close attention to (and I think is equally important) is overload recovery. Records have ticks and pops, cartridges have tip resonances, and their output is proportional to frequency.

The D3a is a superb tube for phono. And it also can swing a lot of volts cleanly.

rknize 4th April 2009 01:59 AM

Quote:

Originally posted by SY
Couldn't agree more. What Morgan also paid close attention to (and I think is equally important) is overload recovery. Records have ticks and pops, cartridges have tip resonances, and their output is proportional to frequency.

The D3a is a superb tube for phono. And it also can swing a lot of volts cleanly.

Yes, recovery is exactly why I want to build a tube phono stage. The SS one I have now is horrible in that way, especially with my new speakers. My LP collection is mainly stuff from my teenage years plus a bunch of other used stuff. They are not in pristine condition by any means. I have CDs for most of it, but some of the CD mastering is just crap.

So MJ's "practical" preamp has seemingly comparable power supply isolation between stages, as each has a separate CCS. Aikido is attractive due to its impressive PSRR.


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