1. Home
  2. analog
  3. 1425797712

Tube phono preamp distortion - help

Hi everyone,

Having some very frustrating distortion issues with my new Jolida JD9 Mk2, and I have tried everything I can think of. My rig was working without issue with the following setup:

Project Debut Carbon w/Otorfon 3M Blue
Vincent PHO-8 Phono Stage
Simaudio i-1 integrated
Tekton M-Lore speakers
Silnote IC, phono cable, and power cables
Clear Day double shotgun speaker cables

So, the only change I made was to remove the Vincent and hook up the Jolida. The Jolida has several settings that need to be chosen:

A. Three voltage gain switches: I set this to low (for MM cartridge, as recommended). The medium setting was unlistenable, and I didn't bother trying the high setting.

B. Eight impedance switches (100, 300, 1000, 47000 ohm, and 47, ,100, 150, and 220 Pico Fared). I set this at the recommended 47k ohm for the Otorfon Blue. I tried the other settings out of curiosity, but none sounded as good at the recommended setting.

C. Two RCA outs: High (1.8 volts for an integrated or line stage) and low (500 millivolts for high gain preamp separates). I connected from the High out to my Simaudio integrated.

This combination of settings is by far the best sounding. However, I get terrible distortion in the higher frequency ranges - upper keys on the piano, female vocals, etc. The low and midrange are fantastic, but the higher range just degrades into a static-like warbling sound (as if it's being overdriven) in both channels with each rise in a singer's voice or striking of the piano keys. It happens on every record and in both channels. As soon as I put my Vincent phono stage back in, everything returns to normal.

I have tried everything I can think of:

-Placing the phono amp further away from my gear
-Trying different inputs on the Simaudio integrated
-Using every possible combination of the switch settings and the RCA outs.

I'm relatively new to vinyl, and I see why some people say it's too much trouble. However, I'd like to find a way to make this work.

I'm open to any suggestions - ready to experiment! Thanks for any ideas!

Best,
Scott
smrex13
smrex13 OP
423 posts
 
THANK YOU! I appreciate all of the suggestions. I tried a few different things, and it turns out that Dill was spot on. I turned all the gain switches off and ended up turning on #4 and #8, which gave me the best sound. I still far prefer the high output RCA connections as the low output seems to give a somewhat muted sound with rolled of bass.

In any event, it looks like I'm good to go! I do wish that the instructions with the Jolida were clearer. And they suggest starting with the med gain switch turned on - WAY too much.

Thanks again, now back to the music…

Best, Scott
almarg's avatar
almarg
8,673 posts
 
Great!

Regarding the sonic differences you described between the high level and low level outputs, that is most likely resulting from differences in impedance interactions between the phono stage and your integrated amp. I see that the i-1's input impedance is spec'd at a somewhat low 11K, and was measured by John Atkinson as being "11.3k ohms at bass and midrange frequencies, dropping to 7k ohms at the top of the audioband." The output impedance of the JD9 MkII is spec'd at 600 ohms, but the design most likely uses an output coupling capacitor which will result in the output impedance rising to considerably higher values than that at deep bass frequencies, perhaps several thousand ohms at 20 Hz. The interaction of those two impedance characteristics is very consistent with your observations of "a somewhat muted sound with rolled off bass."

And it seems very conceivable that the output impedance of the JD9's high level output is significantly lower than that of the low level output, causing those effects to be minimized or eliminated when the high level output is used.

So as long as using the high level output doesn't result in anything being overdriven and audibly distorted, and doesn't result in your having to use the volume control undesirably close to the bottom of its range, you are good to go. Enjoy!

Regards,
-- Al
blowngsr2817
1 posts
 
Hello everyone,

I apologize for resurrecting this old thread, but I’m having the same types of issues as the original post with my current setup with distortion in the higher frequency ranges using the following setup:

Audio Research LP1 Phono Preamp
Denon DL-103R
Bob’s Devices 1131 SUT (distortion occurs at both 1:20 and 1:40 settings)
Rotel RSP-1572 Line Preamp
Rotel RB 1090 Power amp
B&W 804s Speakers

I was able to get rid of the distortion by swapping out the Bob’s Devices 1131 SUT with the Denon AU-320 using the 40 ohm setting, but loved the sound from the 1131 SUT when it wasn’t distorting at the higher frequency ranges, so I would prefer to use the 1131 SUT if the distortion can be fixed.

Any suggestions or recommendations to help solve the distortion issues would be greatly appreciated. Thanks in advance for your time and help.




-Ray

More to discover