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In Reply to: Jolida JD-9A for $450 new. /nt\ posted by HenryH on December 15, 2005 at 06:50:12:
It appears to be a SS phono preamp with a tube buffer output which probably accounts for extremely high gain specifications. unless the specs are wrong I can't imagine this thing working comfortably in most systems. Perhaps they designed it to work with an "integraed" amp which is just a passive input control in front of a tube amp.But it could be interesting for those wanting to go passive preamp.
Follow Ups:
I'm using the JoLida JD 9 and from my limited perspective (have always used stock amp/receiver mm phono stages), it's a very nice sounding phono stage. The gain is incredible. (Yes, those specs are for real!) It has plenty of versatility with multiple combinations of mm/homc/lomc, impedance/resistance, capacitance, and gain. And with a tubed output you can customize the sound using different tubes. Something I have yet to try, but am looking forward to.Right now I'm breaking in a mmf-7/Eroica H combo using 1k ohm, 100 pF, and 85 dB gain. It's a good starting point to help ease the initial brightness of the new cartridge/new phono stage. After 20 hours or so it's starting to sound nice and smooth with lots of detail. With that amount of gain I can leave the volume settings at similar levels for both the phono stage and cd playback. Not a big deal, but it is convenient.
Using the info provided by Jolida with a typicl MM cartridge, a Shure V-15 for instance, the voltage at the line level output of the phonostage is 11 volts!Using the 95dB gain with a 0.25mV MC cartridge yields 14 volts output!
For comparison the Bellari with "only 30dB" gain yields 1.1 volts with the 3.5mV Shure. Hey what do you know that's just right!
Signal peaks can be as much as 20-dB greater than a cartridge's rated output at 5-cm/s. This would raise your 0.25-mV MC from 14-V to 140-V. I seriously doubt this unit has any greater gain than 65 or 70-dB for low-output MCs and 45 or 50-dB for MMs.
You are correct, sir! That's what I've been trying to figure out myself. I posted this question previously and didn't get very far. I've yet to call JoLida to ask about it.When I tried to use the "line stage" output (HIGH OUT) the gain was so high you couldn't use it. But when I instead used the "RIAA" level output (LOW OUT) it's more reasonable. Still higher than typical phono stage gains (at least from what I've read and others mentioned) but within a more normal range. So that's what I'm using and it sounds very good.
Don't know what to say other than the HIGH OUT may be, as you said, for passive preamps and their "RIAA" output is actually closer to everyone elses line output. Here's what JoLida's owner's manual states:
"LO out: 200 Millivolt output for use with preamplifier separates."
"HI out: 1.8 volt output to integrated amplifiers or line stage preamplifiers."Doesn't add up from my limited experience. What do you make of it?
20dB (ten times) which is what one would "make up or add to" from a typical line level preamp.But the low output is "painfully low" even when using a line level preamp.
I betcha one of the outputs goes through the final tube stage and the other doesn't. That's what is called the "token tube" circuit.
Garth, you got me worried about the low output bipassing the tubes so I just called JoLida. Very helpful and willing to talk about their product(s).They designed the JD 9 to be VERY flexible, able to handle just about any mm/homc/lomc cartridge and pre/passive/power/integrated combination you can think of. BOTH high and low output run through those 12AX7 tubes. It's designed so the high output can be used with passive preamps or integrateds with passive gain (such as the Creek integrateds) and the low output can be used for higher gain preamps/integrateds (such as my Musical Fidelity integrated) and either way you get the advantage of tubed output. Very nice.
So, the JoLida JD 9 provides high/low gain tubed output, mm/homc/lomc gain input, 4 levels of input resistance/impedance, and 4 levels of capacitance, easily accessed on the back panel. Very nice.
I'm a happy camper.
Tom
PS: They've got something interesting (I think) in the works.
Henry
the output appears to be VERY high, unless I'm completely and totally stupid, dumb, and incompetent. Well, that's besides the point. The specs JoLida states seem to be close to what I'm getting. And this guy also experienced (see link below):
Dumbo El Stupido.
I read the article and it seems to confirm both our suspecions. From the two words on the web site I figured the tube(s) was on the output after the actual phonostage output which probably gives that final 20dB boost difference.No offense but anyone buying this product thinking he is getting a tube RIAA phono amplifier was tricked. That doesn't mean it doesn't nor can't sound good. I happen to use a SS RIAA phono amp and SS line preamp.
To test whether the LOW OUT runs through those tubes, I guess I could buy another set and swap them out to see if I hear a difference. If I do, then it's as it should be. But if I don't, then 1) there's no difference in sound between the tubes I try, or, 2) there is but I can't hear the difference, or, 3) the low out does not go through the tubes, or, 4) both 1 and 3, or, 5) both 2 and 3.Maybe someone else with a JoLida JD 9 that does have a spare set of 12AX7 tubes could try testing the LOW OUT to see if it is in fact a tubed output.
Tom
Just turn off the unit and pull the tubes. Turn it bac on and if both are dead then it does indeed go through the tube output in each case.
I pulled the tubes (they're Electro Harmonix tubes by the way) and sure enough it appears that both HI OUT and LO OUT use the tubes as explained to me by JoLida.And then it gets interesting. The outputs were not dead. But both had much less (relative) gain and were noisy, sort of like a gentle breeze across a microphone. I put the tubes back in and the rich full detailed sound returned.
So yes, Virginia, the JoLida JD 9 has TUBED output for both output levels.
a thought did occur to me about the seemingly odd occurance of sound coming from both outputs without the tubes in place...Could it be (I may be crucified for this, but) that with the tubes removed there is a bias voltage difference appearing in the circuit and perceived as if it were a signal, when it isn't?
[flame shield status= up]
Garth,
Several inmates have them and recommend them highly.
Henry
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