Vincent PHO-8? Jolida JD-9A,? Phono Pre's $350-500

Johnnyb, as I mentioned to you on another thread, the tubes in a JD9 are not in the gain stages. In the JD9, they're used just as 'cathode followers' at the output, in the hope of warming up the sound a little, but that's way different from the "sound of tubes" when the tubes are actually used to amplify the signal.

Anyway, because the tubes in the JD9 aren't providing any gain, it really shouldn't make any (sonic) difference which 12AX7's are used (assuming they're quiet and not microphonic ;--) So there's not much point (IMO) using premium NOS tubes. I tried using 3-mica blackplate RCA and Sylvania 5751's in my JD9 and couldn't hear any obvious change. Except the 'better' tubes seemed less prone to picking up radio stations with the volume wide open ;~))

The op amps are another matter, and I might try changing those. Right now, the sound can be a bit tinny or grainy; especially on loud passages with female vocalists. Only there seems to be some confusion about WHICH op-amps. Here they recommend 637's and the JD9 mavens on AA recommend 627's. Does anyone know what's in the stock unit? It says 'OP37G' which is a low noise, high precision Texas Instrument op-amp. So maybe Jolida has already upgraded the op-amps in their current release units?

Neil
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If you go here and scroll down a bit, you'll see three levels of mods for the Jolida JD 9A. Mods for this unit also show up in DIYAudio and other places.

Six months after taking delivery, I still like my JD 9A a lot and have no desire to change. I think it's one of the best at the price if only because it is so configurable for capacitance, resistance, and gain, while most others in this price range are not.

While I swapped the stock tubes for Sylvania NOS 5751's, that's because I had a pair lying around the house. I put the tube dampers on because I think controlling microphonics in a unit with this much potential gain is a good thing.

Still, I wouldn't be surprised if I look into the mods sometime, though.

Hi Johnny,

Yes, I'm aware of the two levels of the Underwood mods; but the latest (as of last week) factory-modded JD9's now incorporate most of those mods, and for far less money. In addition some items that Underwood performed as "mods" on earlier vintage JD9's have been incorporated in the basic stock model. So if/when you consider upgrading your own unit, I suggest you send it to the factory who (I'm pretty sure I read somewhere) will upgrade older units. PLUS: Jolida seems to be suddenly using better stock parts, e.g. really good op-amps: the Texas Instruments OP37G which I mentioned above, and which came as quite a surprise when I opened my JD9 to 'have a look'. So no need to upgrade the op-amps in the latest model (IMO) -- and that's VERY important, because the op-amps (not the tubes) represent the "heart" of the JD9 ;--) Also, my "stock" unit came with the Russian made Tung-Sol reissues, which are more than adequate for a buffer stage. The folks that are madly tube-rolling buffer stage tubes, and imagining they hear sonic improvements, just crack me up because their O/C energy is so completely misdirected! ;--))

BTW, regarding tube dampers. First of all, the stock tube shields are spring-loaded and provide BETTER damping than EAT's or Herbies. Second, far more important, and almost impossible to cure, this phonoamp design seems to be susceptable to RF interference, at least in my area. And although I CAN (barely!) hear a radio station at high volume (no signal), it still bugs me. So use those tube shields and get RFI protection and damping too!

I agree with you that the JD9 is a really nice phonoamp for the price. Especially for use with low output MC's. If one is only going to use MM or HOMC cartridges, then I think one can do better for the same money. I also think a lot of new audiophiles get seduced (by other newbees and dealers like Audio Advisor) into buying relatively inexpensive components and then going "tweak-crazy" -- imagining they can upgrade them to 'Stereophile Recommended A' status . . . . NOT! So with a unit like the JD9, the trick is knowing when to stop tweaking; enjoy it for what it can do, and eventually, buy something that needs no "improvements"!

So I'm going to sell my JD9 very soon because I don't need two solid state phonoamps; and the one I already have exceeds the JD9's performance by a wide margin in every way except versatility/convenience (which I don't particularly need.) Anyway, I never would have bought the JD9 in the first place, if Jolida hadn't lied (yes, LIED!) by calling it a "Tube Phono Stage"! Because all I wanted was to (inexpensively) compare the sonics of a (real) tube phonostage with the sonics of my solid state phonostage -- and thanks to Jolida, that task is still on my agenda!

Caveat emptor!
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