Hi Venaka,

Here is some information regarding the parts replacement/reference: if you need more detail just ask:

a-.Regarding the rectifier diodes :
I have changed all the 8 diodes and you can see their location highlighted by the yellow arrow below:

b-.Regarding the VTA-53 tube output resistors :
The location is pointed out herebelow:

c-.Regarding the VTA-53 tube input resistors:
The location is pointed out herebelow:

Do not hesitate to ask if you need more detail..

Hey guys great write up with piks!! ..Ok found the fairchilds stealth in digi, but the yamamura is so hard to find. Can you guys let me know where I can purchase these hard to find resistors.

The Yamamura are very difficult to find because they are no longer in production (they were previously manufactured in Nice, France). They do not exist in all values. A place where you can maybe find them is Percy Audio. But if you do not find the correct value in Yamamura, you can use another excellent resistor such as the Amtrans, Takman, Allen Bradley, etc... all available from HiFi Collective.
They do not all use the same tehnology and therefore each one as its sonic personnality, but compared to the original crappy VTA-53, they all belong to another league... You just have to test which one you prefer: it is mainly a matter of taste.
Regarding the above Im super nube confused and I am seeing six resistors. Are all these six resistors the same 2kohm 2w?

SOrry for my dumb questions but Im going to try this on my own.

No, I just had to solder 2 resistors in paralell because I did not find the correct value in the Shinkoh range. In that case, to get a 1 Kohm resistor, I had to soler two 2 Kohm resistors in // in order to get a final value of 1 Kohm.
SHINKOH-72832
Is this the item number?

I do not know where you have got this number, but you just have to order a Shinkoh (or another high quality resistor) able to handle 2W (minimum 1W is enough) , in a correct value, OR mount two of them in // to get the appropriate final value. Just go to the HiFi Collective website (for example), and you will find a lot of choice !

All the best, and keep us informed,

OK by reading your question I have seen that I had forgotten to provide the information in the English version of the article ! this is fixed...

The 2 resistors you point out were initially two VISHAY VTA-53 with a non standard value of 324 ohm.

They have been replaced by the closest value I found, i.e. 329 ohms (Shinkoh, 2W, from HiFi Collective).

Do not hesitate to ask it is still unclear....

1K2 Shinkoh 2W Resistor

Would I be able to use these, I couldnt find the 2k 2ohm in HIFI

NO: this value (1K2) is too far from the 1k value we need. To get a 1K value from the available existing values, your should solder a 1K5 and a 3K in parallel. These two values are both available from HiFi Collective in the Shinkoh 2W range.
Just look at the photo, it is exactly what I have done, you can see two resistors soldered in //.

For your information, when you sold two resistors R1 and R2 in paralell, the resulting R value is defined by: 1/R=(1/R1)+(1/R2).
also I cant find this..YAMAMURA with a 39 ohm value..can you please give me another resistor that would be almost the same.

A Yamamura 39 ohm is available from Percy Audio (you can download their PDF catalog online), but you are not obliged to use a Yamamura resistor: another good resistor can be used. The perfect value is 47R, but 39R will work fine.

All the best,

Hi Venaka,

I am very happy to see that you have got the sama amazing improvement than me by performing the same changes ! I confirm that these changes are amazing...

Regarding your question related to the diodes , I confirm you that the upgrade of the diodes is VERY important : it provides a smaller improvement than the rest, but allows the other upgrades to perform at their best. Provided that you have already upgraded the rest, the upgrade of the diode is a MUST HAVE....

Keep us informed !

Hi Venaka,

I recommend you proceed as follow:

-replace the small diodes of the Conrad by the 4A 600V diodes , FRED and Stealth, that you can order from Percy audio : http://www!percyaudio.com
-replace the other 4 diodes, that are bigger, by the 8A 600V model, that you can of course also order from Percy.

Keep us informed about the improvement you will see,

Can the bigger diodes also be replaced by the same 4a 600v...

I have already replied by email but I give you the information:

Based on the Conrad-Johnson schematics of the CJ-Premier 10, the big diodes are named FR-304, which are rated 3A 400V according to the datasheet.

So there should normally be no problem to replace them by 4A 600V diodes...
I have little experience, but by watching him it doesnt look so hard.

It is not difficult to do: the only problem comes from the lack of space to solder the new diodes: on the CJ-10 there is not enough space to approach the solder iron, but be serious and uou will succeed !

All the best...

I performed the upgrade to my CJ Premier Ten Preamp following the instructions provided in the article by Florent and Nounours. Total time invested was under six hours. This included shopping for parts online, and performing the actual upgrade. The actual soldering and desoldering process took about two hours.

Some of the parts they used in the article are getting difficult to find, here in the United States. I also used Clarity Caps, and all Shinko resistors purchased from HiFi Collective. In place of the 1k resistor, I used two 500 ohm resistors in series. The diodes they used were a little more difficult to find. For the 4A 600V diode, I used ILS9R460PF2 purchased off of Ebay. I had to purchase a tube of 50 4A diodes to get the four that I needed. For the 8A 600V diode I used a Motorola MUR860, also purchased off of Ebay. I chose to put on a thicker power cord that is 12 ga and hardwired it in to the preamp. I used silver solder on all solder points. Total cost of all components to modify this preamp was around $280.00 USD.

Powering up the unit is always exciting after you perform an upgrade. Did I make any mistakes? Do I have any solder bridges? Will it blow any fuses? Will smoke come out of it? Will any diodes pop? None of the above. It powered up like it always does.

My system is: B&W 801 Series3 speakers, biwired with Monster Powerline 2 cables. Amps are VTL Wotan mono blocks running 600w in triode mode. CJ Premier ten Preamp with Transparant Music link cables. Source is an Audio Alchemy Digital Drive top loading cd transport and Thorens 316 turntable.

After powering up the modified preamp, Nick Drake, Five Leaves Left was sitting on the turntable, so I fired it up. It was so much richer and fuller than normal, even though I was walking around the room and not seriously listening yet. I was in awe of how much better my turntable was. Between songs, it was very quiet all of a sudden. When the next song started, his voice seemed to be in the room. I knew that the modification couldn’t make the turntable sound that much better, so I went to get a cold beer and let the system play while I was in the kitchen. I knew that it had to be my imagination.

My next listen was a HDCD of the Dallas Wind Symphony playing Trittico. This music jumped out of the speakers at me. It sounded like my preamp had a Loud button like old receivers and car stereos did from the 1970’s and 80’s had. The bass and treble were both louder. Not only louder but very controlled. I turned up the system louder than I normally do, pushing my 600w hard into my speakers. It was very musical and immediately brought a huge smile to my face. Track 1, Allegro maestoso, gave me goose bumps up and down my arms and a giant smile on my face. I listened to the same track three times before I moved on, because it was so good. There was a lot of depth now to my soundstage. Not just left to right but a very deep soundstage that was wider than most live stages. The modification did make my system sound so much better. My wife describes it as going from two dimensional sound to three dimensional.

I then let the system idle for an hour to warm up further while I cleaned up my work bench after the modification, and finished my beers. My next listen was to Puscifer Money shot. Puscifer is very dynamic and also has very deep bass. It helps that I’d just seen this band perform live a couple of days earlier. Starting the cd transport on Puscifer pushed me back into my chair. I truly was hearing and feeling things in the music that I’d never heard before. Between songs the sound stage was perfectly quiet for once. When the music did start up, I closed my eyes and imagined myself in a concert hall listening to my favorite band. I could picture each musician in their own place, and very defined as to where they were standing on stage, with some standing in back, and some standing on the front of the stage. The imaging of where each musician stood was not something that was so defined before the upgrade. The upgrade had a huge effect on soundstage imaging in all directions. My bass seemed to be louder and more controlled to the point that I turned the volume control up higher than I’d dare to do before. I caught myself tapping my foot heavily and dancing in my chair as bass waves were hitting my chest. I could feel the bass hitting my spine, and I was enjoying every note of it.

My only complaint if there is any, is that I may now have too much bass. It is a little bit of a change for me, because it always was a little light on bass before. I will work on my sound panels in my listening room to capture some of my extra bass, or change some area rugs.

Am I glad that I performed the modification?? You bet I am. I am enthusiastic about my music the last two weeks since I did the modification. Would I do it again? You bet I would. It’s like having a new component but not having to pay for it. My wife even said that she was hearing things that she’s never heard before on some cds. I just hope that the sound continues to improve as it burns in the individual components. I’m not saying that this modification is the best thing out there for everyone, but with my system configuration, the modification was exactly what I needed. If anyone is contemplating this modification, I can highly recommend it over the standard CJ Premier Ten.

Three weeks later now, and the sound has gotten a little bit better yet. My wife hasn’t noticed it change, but I have. Or at least I think that I have. It seems to have mellowed out just a little bit, and the soundstage has gotten deeper yet. Some of the brightness has slowed down, to make it sound a little bit smoother too. I’m still loving the new modification and caught myself dancing in the kitchen to the stereo that is on another level in the house. I’m enjoying it immensely.

Thanks for providing the information on the CJ upgrade!! Dan