Jolida Jd9 Mod Project

[Wire Nut]

I found it necessary to buy a new phono preamp because I wanted to do the wood body mod to a Denon DL 103r but the vintage PS Audio PS III did not have enough gain for it as it has a low output of .25
.
After some research I landed upon the Jolida JD9. I had a highly modified Jolida amp before and liked it so I called my friend Kenny over at the Needle Dr. and he ordered me a black one. This post will be about the journey of modifying it!

Here are the two posts I found that gave me inspiration to get the Jolida and to modify it:

.com/index.php?topic=62730.0

http://www.diyaudio.com/forums/analog-l ... ation.html

Here is what I am preparing to do with mine:

Obbligato 1.5 caps
Vishay bypass caps on above
Tubes (Ei vintage, Tele smooth plate, or Mullard long plate- one of these should be the cat's meow with the new cart)
B-Quiet with carbon/copper strands glued on top (damping & anti RFI)
Quiet Kote spray paint on the lid (damping)
ERS on the top (anti RFI from Sillpoints)
Parts Express anti-vibration sheet the on bottom (damping)
Gold Alloy wire to replace key wires
Neotech wire to replace long run to circuit board
Op-Amps
Power cable (very tasty vintage Western Electric 14ga)

Below is a photo of the B-Quiet that will go on the inside of the JD9:


Below is a photo of the Parts Express damping sheet, the Quiet Kote, and the ERS sheet:

[GaryA]

My jd9 got the full treatment from parts connection and I also changed all of the op amps using recs found online. I also have a Zu Denon 103r (and 4 or 5 more) - I am very happy with this phono-amp: it jumps and sings and projects pretty pictures. It will need 20 or 30 hours of burn-in so you might want to delay installing the vintage tubes. I hope you like it a lot, and look forward to your reactions.

[AudioSoul]

So your buying a brand new JD9 phono preamp and your going to mod it right off the bat? You have more patience than I have. That is a great phono pre by the way. I can only imagine what it will sound like when you finish moding it......

[Wire Nut]

I got the call, my JD9 arrived at the Needle Dr and I drove right over there and picked it up. It was heavier than I expected, and when I opened it up I was surprised by the quality for the $$.
I was also surprised that mine looked a little different on the inside than the ones on the other posts.



The first thing I did was put in the new caps, I just put the wires where the stock ones had come out:



I put the B-Quiet on the bottom of the inside & the Parts Express stuff on the bottom of the outside. I didn't like the shiny look of the B-Quiet so I put the ERS over that.



You can see the ferrite cores I put in two places. I also hate vibration so I added Blue Tack. The top has been sprayed with Quiet Kote on the inside and I glued carbon fiber strands over that to disrupt EMI & RFI, I painted over that with vinyl spray for outside furniture.

The stock Tung-Sol tubes sound pretty good, but the highs roll off pretty quickly. I tried the Tele's but they were a tad bright, next the Mullard's which had the bass of the other sets but were smoother, the Ei's had a little too much midrange and the Mullard 4004 were also too bright. I settled on the regular vintage Mullard's.
Even with the few things that I have done so far- I am DELIGHTED with the way this preamp sounds. Talk about a great value, the SQ of this unit blows away the PS Audio I just sold. It has excellent bass authority, silky mids, and nice definition on the highs.

I was going to replace some of the wires on the input, but it is a hornets nest in there so I probably will just do the output wire as that looks pretty simple. I got some nice cryo treated Neotech wire for that.

My op-amps have not all arrived yet, I had really good luck with the OPA627BP in my Ah! Tjoeb so I am going to use a set of those in the middle.

[Wire Nut]

New discovery: I can state with authority that the brightness that some of the other forums have spoken about from the JD9 are from the internal wiring they use. I put in new output wire and much of any upper-mid harshness or brightness was gone. (there wasn't much with these tubes to begin with) But the sound is a bit more refined at all frequencies.



I also have four of six new op-amps in place; one guy on the circle said the magic combo is to have the AD843 on the left, the OPA627's in the middle and the LT1028 on the right- I have the 627 and 1028's in place & it sounds pretty good, not earth shaking but better by a tad in clarity.

[GaryA]

As I said earlier, in 2008 I had a bunch of caps and some other components changed by Parts Connextion (level 3 from Underwood Hifi) it includes a bunch of black gates nos tubes and stuff (my knowledge is underwhelming, I know).

http://www.underwoodhifi.com/mod_jolida ... r-Ne-26793

I can take a pic or two when I get the time to take the cover off.

But, I changed the op-amps myself according to the same advice that you found. So just to reiterate what I put in (as seen from the front of the unit): Left AD843 for the output, Middle OP627, Right LT1028 for the input. I had a bit of a problem figuring out how to orient them so that the top was on top as they fit just as well backwards. But when I got them right and let them burn in for 24 hours or so things sounded great to me and I continue to love the sound.

[GaryA]

One other thought/question. The ferrite cores that you put in - did you listen with and without them? I tried to use them on my power cords many years ago and decided that they were mucking things up so into the parts box they went.

[Wire Nut]

Gary, I have tried ferrite cores and had mixed results; I found that if they were outside the box they almost always degraded the sound & usually when inside they helped.
I have the JD9 on my Sony PS-X7 as it has a replay feature so it can burn in for a couple of days.
Once the 843's arrive I will listen with and without the ferrites, I will listen to the new op-amps vs the stock, and go through the tube assortment again.
I would really love to know where the Black Gates go and what value to use, I put BG's in my Kenwood tuner and they sound so musical! A couple of guys put "Naked Z's" in their units, my boards look different so I can't figure where they go- I would like to do that as well.

Oh- for the op-amp orientation, always have the little notch pointing the way the original ones were... which is to the front in the Jolida.

Thanks for your great feedback and help.

[Wire Nut]

I made some more enhancements, I put Quiet Kote on the inside of the two shields:



I tried putting the gold alloy wire on the output as well as the wires running to the tubes, but that took too much of the high end out - so I put the Neotech back and it absolutely sings now.

Here is a photo of the all gold wiring before I yanked the output and replaced it:


The ferrite cores do not degrade the signal at all as I only have them on power wire- not on the signal wires.

I can say that the JD9 with the mods is a very musical box, way beyond what it has a right to be for the money.

[Wire Nut]

I would like to upgrade the resistors and addd some more resistance as the JD9 has a lot of gain. Can anyone tell me the values of the #3 gain switch:



And the third DIP:

[Wire Nut]

There are some really great updates on JD9 mods over at the Circle:
.com/index.php?to ... 30.new#new

[Wire Nut]

Replacing the resistors proved to be more challenging than anything I have tried to mod thus far. I purchased some Caddock and messed them up. Then I got a schematic from Jolida and got the correct naked Z resistors and I still have no gain... I am throwing in the towel and sending the unit to Jolida this week!!!!!!!!!!!!!
I am asking them to put the resistors in the space for the MM carts and for the low output Denon 103r. I will post photos when I get it back.
Bummer!

[timtoy1]

Wirenut

Can you post or send a copy of the Jolida JD9 Schematic?

[Wire Nut]

Jolida was kind to give me a copy of the schematic... however part of the agreement was not to post it anywhere. Sorry
They are super nice and if you fax them a copy of your sales invoice they will probably send you one.