[avahifi]

At long last I have designed a high gain moving coil phono preamp and have a couple of samples of it running.  One is in a free standing little chassis and the other built into the mother board of a brand new Fet Valve Cathode Follower preamplifier.  Both are very musical and dynamic and detailed, both are reasonably quiet, and both could be pretty inexpensive in the overall scheme of things.  It is NOT a head amp, it is an integral high gain phono stage. This eliminates a lot of extra circuits and noise and distortion possibilities.

I am using them with a Longhorn Denon DL103 cartridge and am very happy with the overall musicality of my system.

The only catch right now is that there is no easy way to switch gain or load to optimize from one cartridge to another.  It is all hard wired into the very compact circuit board area to minimize noise.

One way I can deal with that is by simply offering two phono sections built in new AVA preamps, one for standard MM cartridges and the other for MC cartridges.  We would still need to know the optimum loading needed for best results with your unique cartridge(s) and build that in for you.

The option price built into the preamp would be $299 for the MC version and $249 for the MM version, same as now.

Anyway, I am interested in having an AVA client here give the MC version a test run for us.  Again I will need to know the recommended loading and the gain of your MC cartridge to set it up for you.

Please contact me if your are interested.

Sincerely,

Frank Van Alstine

[plaf26]

Hi, Frank,

Sent you a PM about my DL 103R.

[Listens2tubes]

  Would this be possible in my T8+?

[plaf26]

OK gang, I'm going to try and do this without gushing.  Much.

Some years ago I bought a Denon DL103R to find out what all the moving coil hype was about.  I put together a K&K Audio step up transformer kit so as to play it through my AVA T8 (small box) all tube preamp.

I haven't used it much over the years, so my interest was piqued when Frank offered his MC preamp prototype to a local customer to try out.  I picked it up last Monday.

Here are some of the notes I jotted down from listening to this particular combination the last four days:  very quiet...if there's any hum it's below the noise floor and you have to turn it way up to hear that...better balance...better articulation...horns have better buzz and snarl...less mushy bass (three bass drum whacks where before heard only two or one long rumble)...orchestral instruments better able to hold their own against each other...you can follow a particular instrument in the crowd better...less surface noise...better able to tell when instruments of the same family (reeds for example) hand off the melody from one to another...more toe tapping urge...more musical somehow...brings out more of what people buy MC's for.

I didn't want to swap back in the trannies for comparison, but I knew I had to be as objective as possible in a highly subjective process.

I had to look up "split passive RIAA EQ."  I had no idea how complex the whole matter is.

I don't want to go back to moving magnet or moving iron cartridges.  I like this set up so much I'm going to ask Frank to retrofit my small box T8.  The board itself is quite small and should just fit.  It has six IC's--four socketed and two surface mounted.  Very neat layout.  This prototype unit is mounted in one of Frank's standard boxes with an AC power supply consisting of toroidal power transformer, full wave bridge rectifier, and assorted voltage regulators and filter caps.  All solid state and very sweet indeed.

Here's the associated equipment:  SL1200Mk5 modified by KAB (see the whole thing in the "Systems" section); DL103R in Sumiko headshell using Technics overhang gauge (Stevenson alignment); AVA T8; AVA Fet Valve 400R; Maggie MMG's; biro Kensington subwoofer.

Highly recommended

[avahifi]

Thanks very much for the thoughtful review of our new moving coil phono section.

Each channel uses two ICs (Burr Brown OPA627s) and one LME49600 current buffer.  The surface mount current buffer is unity voltage gain, just a great way to isolate the second EQ section from the real world and provide high drive current and a low output impedance to interface with the real world.  We used the very expensive OPA627s in the moving coil version to be able to maintain a direct input to output path even thought this gave up a slight theoretical noise advantage.  Other useful ICs would have required input capacitors to avoid putting current flow into the low impedance cartridge coils.

The moving coil version built into any of our new preamps is $299 due to the extra cost of the OPA627s.  The standard MM version is $249.  The board will fit in most of our older preamps too, including yours. 

Regards,

Frank Van Alstine

[plaf26]

Today I took Frank up on his offer, brought back his prototype and my old T8 for retrofitting with the new MC card.  Can't wait!  Sure is quiet around here though.  Maybe I can find a comb and some tissue paper to tide me over.

[avahifi]

plaf26 saved me some money!

I had been "told" to buy a Lundahl step up transformer before even thinking about designing my own MC solid state phono preamp because there would be no way I would beat that.

Well, I did not follow that advice and plaf26's evaluation says I was right. 

I have always suspected that the tiny coils in a MC cartridge would just not have the energy to drive a 10X transformer without loosing dynamic range and life.

Our Vision MM or MC phono preamps are available built into most any AVA preamp now, and in some chassis we can build in both.

Of course they are available as free standing units too.

Frank Van Alstine

[plaf26]

Well, Frank wasn't able to fit the MC board into my old T8 small chassis.  It would have taken the place of the tube phono stage, but there just wasn't room enough to keep it away from the power transformer and the added noise that could cause.  So we decided to go with the free-standing unit with it's own power supply.  That's probably just as well, since I can keep the tube MM stage for use with my Longhorn Grado 78 on my brother's old shellacs.  It's amazing how much sound there is in some of those old platters!  Dean also found my line stage tubes were soft, so those got replaced.  So, thanks AVA, they're all back in the rack and sounding great!   

[Minn Mark]

plaf26,
 Interested to hear your impressions. I recently got the Vision MM in my Insight+ preamp, and have been posting here in the AVA circle.

I like this new phono stage very much. While it is different than the previous Insight phono I had been using, I immediately hear it's improvements.

Please share your thoughts once you get the Vision MS.

Happy Holidays,

Mark

[plaf26]

Mark,

Since my Vision MC preamp is the very prototype Frank let me try out (he cleaned it up and gave me a great deal on it!), my remarks are the same as above.  Except that I forgot to mention what appears to me to be improved dynamic range.  The louds are louder and the softs are softer.  I can't stop listening to the thing.  I'm going to try to insert a picture of the unit on top of my Vision Basic DAC.  Both of them are in the older small boxes.  How's that?

plaf26