Jolida JD9 Upgrade/Mods Clarification. - Page 4 - diyAudio
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Old 28th December 2012, 11:07 PM   #31
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Quote:
Originally Posted by Mohan Siribadda View Post
I intend to mod my JD9 which I bought from a seller at Audiogon. Before I carryout this mod, I need to change the operating voltage from 120V 60 HZ to 220V 50HZ. Can anyone advise me how I should get about on doing the power conversion. I have tried to get the information Jolida USA, unfortunately they have not responded to my request.
I think all you have to do is switch the voltage switch inside the unit. You can see it on the picture here at this link (and in the mod download instruction guide which is also available there):

Jolida JD9 phono preamp Upgrade Guide
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Old 29th December 2012, 02:02 PM   #32
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In the interests of full disclosure, and hindsight is a wonderful thing, but I think the cap mod was worthwhile but I'm not convinced about switching the op amps or any other mods really.

I'm not 100% I'd put money on a preference in a blind test with op amps anyway and as noted above, half of the changes I made were as a result of someone getting excited on another thread and I the benefits had their pitfalls.

This is an interesting op amp video, make of it what you will.

http://www.youtube.com/watch?v=bpTv2jAree8

The dampening is your call of course but a step too far for me although I hope it pays off (and that someone actually answers your question).

I recently put this against an all tube EAR and it held it's own. I'm a sucker for tubes though (but the prices aren't realistic for me).

Best

Last edited by nathanjh13; 29th December 2012 at 02:05 PM.
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Old 29th December 2012, 03:27 PM   #33
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Hi Invention/Nathanjh13,

Thanks for your advise, as you have suggested, I can do the voltage conversion easily. However, as the instruction manual indicated, I need to change the fuse to 3.5 A, VAC fast blow fuse.

Regarding the upgrade, my seller has sent me the following components:

The details of the parts are as follows:

1. OPA 627 AU- 5no

2. Resistor- 12R- 1No

3. Resistors Riken- 10R gold plated- 8No

4. Resistor Riken- 12 gold plated - 1No

5. Auricap 1.0+/-10%400V- EGA7956-37- 2No

6. Mudorf M E-cap- 220uf 63 VDc- 10No

7. Blackgate Rubycon- 10uF 250V- 5No

8. Tung-Sol- 12Ax7- Made in Russia- 2 Nos.

Kindly advise me the above parts are for which area of the circuit upgrade. It is obvious that tube rolling and capacitor bypass have been anticipated, but the Munforf caps, I believe should be for the power supply upgrades? If you can enlighten me which area I should upgrade first. In other words, what will really enhance the performance of JD9A, is it really worthwhile to full upgrade or should I stick to tube rolling and auri-cap by pass?

Another forum I noted that some have used Bybee Music trail upgrade to the DC power supply. What is your opinion on this direction?

Have a nice day and complements of the festive season.

Cheers
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Old 29th December 2012, 06:35 PM   #34
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Ah right sorry, the only modifications that I have made are in the first few posts of this thread.

I find tube rolling something of a can of worms and not always the case that more expensive tubes sound better. It's been said before but tubes are a moving target and comparison in real world terms is an itch that is, in many peoples eyes, too time-wasting to scratch.

You are geared up to modify many more items than I did so I cannot offer any sensible advice. As mentioned earlier I found the cap changes worthwhile but I'm not sure about the op amp ones.

Listen very carefully I would say.

All the best with it, take good care.

Last edited by nathanjh13; 29th December 2012 at 06:40 PM.
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Old 29th December 2012, 06:47 PM   #35
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I would say the caps and opamps do provide significant value and I would definitely upgrade those two. Tubes will also improve the sound but it's more about personal preference of the sound so I don't think there is a "right or wrong" tube but rather what sounds good to you.
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Old 30th December 2012, 04:05 AM   #36
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Thanks for your suggestion, I totally agree that sound depends on personal preferences. When you go through the part list which I have indicated, can you advise me where the "Riken resistors" and Mudorf Caps" should be replaced. Please do not get me wrong, these parts were sent as a bonus as the previous owner has included these with JD9A. However, the previous owner did not send me any information on the upgrade. When I Googled, I think Level 3 MOD according to:

Underwood HiFi: JD-9

If you can advise me where the parts should go, I shall appreciate you a lot. I wanted to make use of these expensive components on the JD9A, but all depends on how far I should go on the upgrade.

From the discussion I had so far, the capacitor upgrade, tube rolling and OPA substitution are the best options available to take the JD9A to a higher level.

Look for your specific advice on this.

Cheers
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Old 29th October 2013, 09:20 PM   #37
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Default Popping with phono power?

Have any of you guys ran into a large popping noise when you power down your turntable? I have isolated the issue to the phono preamp.
Thanks, Nut
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Old 30th October 2013, 09:21 PM   #38
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Nope.
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"He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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Old 31st October 2013, 12:30 PM   #39
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I have the ground from the preamp attached to the Jolida now- same thing happens. I will contact Jolida as well and post it.
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Old 3rd November 2013, 01:13 PM   #40
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Quote:
Originally Posted by Wire Nut View Post
Have any of you guys ran into a large popping noise when you power down your turntable? I have isolated the issue to the phono preamp.
Thanks, Nut
Nope, never happened.
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