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Marsh P2000T hybrid preamp....Should I modify??

First, I'd like to say how much I've enjoyed reading and learning about high end audio on this site!!

In regards to my question, I am seriously thinking that a modification of the Marsh P2000T is in order. My system consist of a Pioneer Elite PDR-19RW CD player/recorder, Marsh P2000T preamp, Marsh A400s amp, and Magnepan 1.6's.

After reading in this forum about microphonics, I can say that this preamp has a problem in that area. Another issue is that I can only turn the volume control up to about 11:00 or the blue LED on the A400s starts blinking!! It does get relatively loud. I got this preamp as a demo from Audio Advisor for $975, so I could afford a modification. I am thinking that I would send it to Underwood HiFi for the mods. The mod talks about reducing microphonics and lowering the gain from 23dB to 14dB. Those 2 items address problems that I've mentioned earlier.

BTW, I will be replacing the Elite CD player/recorder with a Music Hall CD-25, also modified , either by Underwood or Sound Odyssey. Thanks for your time and thoughts on this matter!!
128x128pummill
dimitry
83 posts
 
I have done simple modifications on this preamp myself. First, change stock feet to "superspike" type or equivalent. Take a 1" by 0.25" aluminum bar and bond it with marine epoxy to the underside of the top cover in the long direction. Then buy a pair of HAL-O damping instruments from Herbie's Audio Labs and put them on a pair of Tung-Sol D-getter NOS 5687, which you can get for under $100 per dozen on Ebay. Finally, put on a VPI Magic Brick at the rear middle of the top cover.

Voila - no more microphonics. The preamp is silent up to -10db attenuation. I have installed a -60 to - 10 db switched attenuator and silver contact selector switches, which I highly recommend. Really good ones are available from www.goldpt.com. Apparently the guy will give you custom 24-step attenuator if you tell him the range you want.

The service you cite looks good and comprehensive, but should include the attenuator for best performance. I consider this Marsh preamp the best line circuit available today. It is made to a price point and can be improved with better parts.
pummill's avatar
pummill OP
34 posts
 
Dimitry, thanks for your thoughts and experience with this preamp. I am not much of a DIY type of guy, so I think I will go for the Underwood mod!!

I do know that when I switched from my old Outlaw 950 pre/pro to this unit, I heard an immediate improvement in every aspect of the sound I was getting from my maggies!! Much better soundstage, more dynamic with much better low end. Then I switched from an Earthquake Cinenova amp to the Marsh A400s amp...now my system really opened up!!
pummill's avatar
pummill OP
34 posts
 
Well, as a follow up, I HAVE sent my Marsh P2000t preamp in for modification at Underwood Audio. I should have it back in a few weeks and will give my reactions and results as they become available!!
dimitry
83 posts
 
I have ordered a pair of mono 100K series attenuators from Gold Point. I will report on the effect of these instead of the Marsh's balance and volume dual Alps pots.
pummill's avatar
pummill OP
34 posts
 
Dimitry,

Can you give me some input on the inverted polarity of the P2000T output. The manual says this:

"The output signal is inverted polarity to the source signal, you may need to change the polarity of both left and right speakers cables to get correct program polarity"

Do I really need to hook my speakers up + to - and - to +??
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