Jolida JD9 phono amp hybrid Magic...

bigdirty · « **Reply #120 on:** 1 May 2011, 07:21 pm »

Quote from: robob on 1 May 2011, 06:55 pm

have you tried playing with the loading caps and resistors?

If you mean replacing them, I have not. I do have the Dip Switch chart and currently am at 230 for my Kleos. I have even tried a few different capacitance setings.

On further listening, it sounds more like an elevated shelf from about 1k to maybe 5k or so. Even with the 5751's it does not have the output on the very top of my GCPH but I can live with that for now. As my room and ears are sensitive to peaky mids and lower treble, this is annoying.

Thanks for your reply,
Robert

I would try the LT1028acn opamp in the 5,6 positions with reference to the pic below. In my system, I have found these to possess the most clarity.

robob · « **Reply #121 on:** 1 May 2011, 11:57 pm »

I would try the LT1028acn opamp in the 5,6 positions with reference to the pic below. In my system, I have found these to possess the most clarity.

Thanks for that. I will try them. Any US suppliers that will sell only 2? What I am finding is the LT1028ACN8 .

BTW, clarity is not my issue and all the specs talk about low noise which is also not my issue. Peakiness is the issue.

That board is under one of the metal covers? Where?

Thanks Again,
Robert

bigdirty · « **Reply #122 on:** 2 May 2011, 12:19 am »

Quote from: robob on 1 May 2011, 11:57 pm

I would try the LT1028acn opamp in the 5,6 positions with reference to the pic below. In my system, I have found these to possess the most clarity.

Thanks for that. I will try them. Any US suppliers that will sell only 2? What I am finding is the LT1028ACN8 .

BTW, clarity is not my issue and all the specs talk about low noise which is also not my issue. Peakiness is the issue.

That board is under one of the metal covers? Where?

Thanks Again,
Robert

The board is under the large rectangular cover near the input rca jacks. 4 screws. the op amps are in sockets so replacing them is a breeze. Digikey is a good source. Sorry I cant address your peakiness issue directly, not hearing what your hearing.

robob · « **Reply #123 on:** 2 May 2011, 09:54 pm »

Quote from: bigdirty on 2 May 2011, 12:19 am

The board is under the large rectangular cover near the input rca jacks. 4 screws. the op amps are in sockets so replacing them is a breeze. Digikey is a good source. Sorry I cant address your peakiness issue directly, not hearing what your hearing.

Sounds good. I am old enough to have put RAM chips in computers.

Digikey is impressive. Even used the chat and someone got to me in probably less than a minute. Ordered the 2 1028's.

Thanks for all the help, I really appreciate it.

Robert
PS: Is bigdirty related to John Bigboote? Pronounced big boo tae, despite Lazardo calling him bigbooty.

bigdirty · « **Reply #124 on:** 3 May 2011, 12:02 am »

Quote from: robob on 2 May 2011, 09:54 pm

PS: Is bigdirty related to John Bigboote? Pronounced big boo tae, despite Lazardo calling him bigbooty.

I googled this... thank you.

To the video store!

doug s. · « **Reply #125 on:** 3 May 2011, 12:22 pm »

Quote from: bigdirty on 3 May 2011, 12:02 am

I googled this... thank you. To the video store!

don't forget: wherever you go, there you are!

doug s.

robob · « **Reply #126 on:** 3 May 2011, 10:13 pm »

Quote from: bigdirty on 3 May 2011, 12:02 am

I googled this... thank you. To the video store!

You are most welcome.

Quote from: doug s. on 3 May 2011, 12:22 pm

don't forget: wherever you go, there you are!

doug s.

Indeed! Goldbloom in chaps! LOL

On to the Topic. My 1028's have left St Paul, MN. Maybe I will have them Thurs. or Friday. If needed, should I do other op amps or caps next?

Thanks,
Robert

robob · « **Reply #127 on:** 5 May 2011, 09:38 pm »

Hello Folks,

I put the 1028's in the 5 & 6 positions and much to my surprise it has not caught fire. Took out what appears to be OP376's. Hard to read but I believe that is what they say.

Gonna let it run for a while before I pass judgement, but it may be high end transistor gear clean with warmth. Like what the 5751's do for it only more so. Need more hours and listening though.

Thanks Again,
Robert
PS: Since nobody else seems to be complaining about a midrange peak, could mine be defective? I have not called Jolida yet.

hibuckhobby · « **Reply #128 on:** 5 May 2011, 10:14 pm »

Mine has a bit of "Bloom" that on some records is awesome and a bit much if they were a bit forward to start with. Mine is in the upper midrange/lower treble area. Tubes helped and I'm going to change caps.
Hibuck....

robob · « **Reply #129 on:** 5 May 2011, 11:04 pm »

Quote from: hibuckhobby on 5 May 2011, 10:14 pm

Mine has a bit of "Bloom" that on some records is awesome and a bit much if they were a bit forward to start with. Mine is in the upper midrange/lower treble area. Tubes helped and I'm going to change caps.
Hibuck....

Thanks for that, thought maybe I was the only one hearing it.

Letting the new IC's burn in some more but the peak appears to be still with me. Please let us know if the caps help.

Y'all be cool,
Robert

robob · « **Reply #130 on:** 20 May 2011, 10:02 pm »

So the op amps made it better but the upper mids are still peaked. Lower treble seems to be better. Went back to the GCPH which is more detailed with more upper highs and balanced response.

Anybody got a good idea for the next thing to try on the JD9?

Thanks,
Robert

roger15ohm · « **Reply #131 on:** 28 Jun 2011, 02:26 am »

Omg, I have been following this tread since years. Great development. So the Jolidah is using single or dual OPa?? I saw 4 of them. wath that means?

thanks

neobop · « **Reply #132 on:** 28 Jun 2011, 11:17 am »

Even though the 1028 has been around for awhile, its quality is unmatched, except by the military version. I don't have a JD-9A, but perhaps one IC in each channel is for regulation?

I suspect the upper mid forwardness is from improper tube bias or lack of tube regulation. This seems to be a common design mistake. I don't know any of this as a fact. Perhaps it's an area that might yield some improvement if you pursue it further. If those are 12A_ series tubes, perhaps they're set for too much gain.
neo

neobop · « **Reply #133 on:** 30 Jun 2011, 11:45 am »

I've been thinking about this preamp. Maybe finding the right tube will solve that forwardness. I notice dramatic differences. You guys must have discussed this before. Is anyone using Genelex Gold Lion? They are said to be great in preamps, specifically Superphon. They cost about $45 each. But I would seriously consider RAM tubes, maybe some Telefunken. I think your best bet is to contact them and get a recommendation.
http://www.tubeaudiostore.com/tubes.html

neo

Wire Nut · « **Reply #134 on:** 2 Aug 2011, 01:23 am »

Guys, is there any consensus on which op amps to use in which place for the best results?
I ordered the JD9 from my friends at the Needle Dr and it will arrive at the store this week (I work just a couple of miles from there)

steveblezy · « **Reply #135 on:** 3 Aug 2011, 12:42 pm »

I put in 6 burr brown OP638BP in mine and the difference was very noticeable.

Steve

Wire Nut · « **Reply #136 on:** 3 Aug 2011, 10:09 pm »

Steve,
Are you sure that is the correct model number as Google turned up no English results?
Thanks, Nut

steveblezy · « **Reply #137 on:** 3 Aug 2011, 10:26 pm »

hehehehe. Thats what I get when responding to a post before my morning coffee. OPA638BP. Sorry about that, I forgot the 'A'.

Steve (now awake)

Wire Nut · « **Reply #138 on:** 3 Aug 2011, 10:35 pm »

Bummer, it appears to be discontinued as there were no english results for that one either.

steveblezy · « **Reply #139 on:** 4 Aug 2011, 12:46 am »

Crap, my bad again, try this Burr Brown OPA 637BP. Sorry, I have been running my ass off on half a dozen projects and I feel that my brain is running on just a few cylinders. You will find references to this chip on the first page of this thread. It is a well known op amp in the audio world. Although it is a little expensive, if you look around, you can find the for less money.

Once again, my bad.
Steve