[Chiswocka]

Looking for helpful people to advise me on key points whilst i pimp up my Conrad Johnson CT6 to the dizziest heights it can reach.

I was going to do a CJ in house C1 upgrade but Jeff stopped answering my emails  He did mention that it consisted of changing 6 bypass caps for teflon caps. The quote to upgrade was quite high so i did what any sane person would do and ripped the top of the unit open to have a gander at what lies below. It looks pretty simple and neat in there, prime rookie upgrade material i thought 

I am chasing more detail/resolution, wider soundstage whilst keeping a musical engaging harmonic sound, not super warm though, in fact an overall boost in performance would be splendid, not much to ask, i know.

So here i am ready to bust a serious cap in this CT6's ass!

My first question would be which are the bypass caps and which the coupling caps, can anyone offer some guidance on this?

Thanks for looking

Chiswocka

[poseidonsvoice]

Find or get a schematic. I have emailed CJ before and they cheerfully sent me a schematic on an older model unit.

Next, high quality close up photos will be very useful. A generic photo like what you have posted will be difficult to discern. DIYaudio is a good place to ask questions as well. I also recommend a site that can hold those photos uncompressed, like photobucket, etc...

Best,
Anand.

[undertow]

This is a fun little project, but what tubes are you using? I know this has 6922's in line. The bigger brother CT5 has the 6H30 which is a little more detailed and dynamic generally, but it also comes stock with the Teflon caps.

I am not against this upgrade, however I assume your looking at doing something like the V Caps or something in that range? Not sure anybody else has the pure teflons accept CJ's own brand, which are likely made by REL or one of the other audiocap companies like the Thetas. I do not have any advice on the exact caps in the critical path so you might need a schematic as stated.

I have the CT5 which you can see here there are even more mountains of caps to sort through! I think it definitely compares to the top 5 preamps of all time. I like the CJ signature more than the big name competitors like BAT, Audio Research, and Mcintosh even using the same 6h30 tubes they are less musical in my opinion. So CJ has something right here, and I am sure a little cap upgrade will take you to that level with the correct "Tube" "Cap" combo, but I would be careful to not go overboard as all the teflon caps will get a lot more tighter sound, and take a VERY long time to burn in.

Good luck with this, but it is a killer preamp I don't think anybody builds a better ergonomic, and high resolution pre with the musical warmth still intact like a CJ

One side note:

Although it seems these have quite a bit of space, the CT5 is a taller unit and Teflon caps can be very sizable so I guess another key here is make sure you can fit these suckers under the hood. Another thing 26 db is a lot of gain, the CT5 only has 20 db of gain so your unit might be a little less forgiving when choosing these caps for tonal qualities especially when using teflon, and you may want to consider some other options like Mundorf Oils, or Jupiters etc... if they are in the values, and physical size you need.

[mick wolfe]

I would suggest leaving it stock and tweaking your system via tube rolling, cabling, footers or whatever to achieve your goal.  Unless the mod is done by CJ, RHB Sound Dezign or Bill Thalman,  the value of the unit will plummet if touched my an amateur. If that's not a priority, go ahead, but I'd have an experienced tech do the work. And yes, get the schematic and figure out what components are to be changed.

[rpf]

I'm not a fan of teflon caps. IME they add an overly smooth, slippery, "glazed" quality (kind of like a bar top with 20 coats of polyurethane on it) to the sound. This was true with a pair of Dodd Mono 50s that I went through several types of caps on, a Modwright 36.5 that came with Modwright teflon caps, and a CJ Premier 17LS that I had upgraded to a Mk. II with CJ teflons.

I'm also not a fan of bypass caps as they smear time alignment.

I am a fan of upgrading caps though, and if you can fit Cu foil caps (Jupiter, Duelund, Rel, even Audyn) in the unit they will provide everything you are looking for.

That said, I have not heard the VH Audio Cu foil, Teflon film caps: they might be very interesting.

I agree with having - at the least - an experienced tech do the work for the above stated reason. Bill Thalmann, when I talked with him some years ago, was reasonable in price.

[undertow]

I agree on skipping the "Bypass" cap route... Although many will argue that's not really the correct term for it. Use a single cap of proper value when possible especially in electronics. This method can be used once in a while with Speaker crossovers, but stay away with signal caps in preamps for sure.

[rpf]

Sorry, duplicate post.

[Speedskater]

I would suggest leaving it stock and tweaking your system via tube rolling, cabling, footers or whatever to achieve your goal.  Unless the mod is done by CJ, RHB Sound Dezign or Bill Thalman,  the value of the unit will plummet if touched my an amateur. If that's not a priority, go ahead, but I'd have an experienced tech do the work. And yes, get the schematic and figure out what components are to be changed.

I 100% support this post!

[Chiswocka]

Thanks for the info people, a LOT of good food for thought. Not quite as simple as one might think : s
Everything else has been tweaked in the system and it does sound great just looking for a little extra shabang, guild that filthy lily!
After much tube rolling i switch between NOS Amerex Herleen and NOS Siemens & Halske. After much cable rolling i have landed on Serblins son in laws Yter speaker cable (contains Palladium don't you know, gotta love that Palladium, alternatively Unobtainium is a good choice, heheeee) to my Cremonas and my own DIY interconnects with Mundorf silver gold wire in teflon tubes then silk tubing then teflon tape then shrink then expandable sheaf and terminated with Klei Absolutes, they are damn good! Harmonic tech pro ac10 is giving juice to all my equipment through a sexy wooden Sonore power filter. The CJ sits on 3 Solid Tech 'feet of silence' for a nice bit 'o' isolation. Just about everything else has been tweaked accordingly, even the tubes in my Cary DAC200ts have been rolled to within an inch of its life, after over 20 NOS ECC82 brands i have settled on Amperex Herleen Bugle Boys, Brimar 6067T, Mullard CV491 and some special UK Valvos. These change depending on the week : ) So that is how i have crash landed on the idea of this next CJ upgrade.
I take onboard the resale value aspect (as it is inevitable in this hobby) and lack of expertise so in mind of all this i will call a local audio engineer today ( i am in Netherlands) to consult on end goal and parts to buy, once bought by myself they will be installed by him, should he agree of course. Shame he gets all the fun for alas C'est la vie.
CJ has been emailed for the schematic, fingers crossed they give this out.
Watch this space!
Oh yes, i did make one small 'upgrade' yesterday that i feel has made things a little smoother in presentation, swapped the stock fuses out with same value hi-fi tuning gold and ceramic audio fuses, could be a placebo put it does sound slightly smoother to my ear, after travelling through 6 tubes i don't always need my music smoother but still its a positive force IMO. Plus i can always switch the Cary DAC200ts to SS, bloody love that DAC I do
Cheers

[undertow]

By the way I highly suggest if that Conrad pre is listed as one of their "Absolute Phase" preamps that you try the Speaker cables with proper polarity, and reverse polarity.

I found that the inverting circuit performance depends on the amp, and speaker combo it gets connected to ultimately. You really have to listen to it and you may find one way is better than the other depending on what your amp is doing with the signal.

Just swap your positive and negative cable on your speaker posts, and try it both ways to find out. When you find the correct way it all snaps into a much more realistic smoother sound stage vs. being more forward, and HIFI. Again don't base your decision on the specs. themselves in this case even if you believe you should have your speakers hooked out of polarity due to the way its explained in the Conrad manuals.

[Chiswocka]

I contacted an audio engineer who has stated it might not be worth upgrading to such a high spec?! Not getting a lot of joy on this right now so i must consider my options.
If i do a full V-cap teflon bypass/Audyn TC or Jupiter C coupling cap/tantulum resistor upgrade it will fall into the same price range as the CJ C1 upgrade after shipping and duties will be paid even cheaper!
I got a good price originally for the unit so all in i would have paid around $2500 including upgrades. It will be upgraded to the highest spec and i wonder if i could find a better pre amp for the money?!
What do you guys think, to my mind its hard to beat the quality of components for the money, of course this is without hearing her but it would surely be a huge improvement from stock? 

Thanks for reaching out undertow. It does explain phase inversion in the CJ manual, there was very subtle changes in sound but i didn't find it conclusive so i employed an inversion test with low , high frequencies etc and the outcome was regular phase terminal layout being correct in this system.

Cheers

[Chiswocka]

I am in Nederlands by the way, thats in Europe if anyone is insure 

[Rocket]

Hi,

How much did Conrad Johnson want to upgrade the preamplifier. It would seem a shame to damage the unit if your not experienced enough
to do so.

Oh course its up to you though.

Cheers Rod

[Chiswocka]

Hi Rocket, just to be clear, i will not be performing the upgrade myself but rather a professional audio engineer. As an engineer by trade and being competent with a soldering iron i am sure i could have a damn good crack at it but as suggested above its best to let it in to the hands of a professional, at least this time round   

The upgrade price is $895, the shipping to and from the states $200+ and duties + import VAT on the upgrade is on all the above so around an extra $300 so around $1400 total. Thats more than i paid for the unit 

Cheers

[undertow]

You did get a ridiculous low price on the unit!

And realistically at this point I would probably just leave it alone. The caps will not be significant compared to the quality Conrad already builds into the unit just different. Unless you have the money, and the itch does not go away than sometimes you just have to do it because your curiosity will not die easy.

I can say it looks like you have 3 fuses inside the unit like the CT5. One main on the back, and the 2 inside. The main on the back should be replaced with a Furutech, or a Synergistic Black, or Red. It makes a difference. Also, ONE of the fuses inside needs to be replaced with similar that feeds the circuit.

The 3rd fuse is just for the front panel display, and relay remote function so no need to replace that as it has nothing to do with sound.

I have done the fuses in these units, and had good results, its a relatively cheap upgrade and far better than the glass fuses you have in the unit now.

Good Luck

[earwig]

Find the output caps in the schematic. I changed some output caps in a old CJ pv5 to Mit rel caps. Tightned up the bass significantly but may change the overall CJ sound.Im sure there are much better caps than those out there now ,watch the physical size dem can get very huge!

[timind]

I would suggest leaving it stock and tweaking your system via tube rolling, cabling, footers or whatever to achieve your goal.  Unless the mod is done by CJ, RHB Sound Dezign or Bill Thalman,  the value of the unit will plummet if touched my an amateur. If that's not a priority, go ahead, but I'd have an experienced tech do the work. And yes, get the schematic and figure out what components are to be changed.

I'm with mick wolfe here. Although my first suggestion would be ensure your room is optimal. Best tweak ever IMO.

[timind]

Find the output caps in the schematic. I changed some output caps in a old CJ pv5 to Mit rel caps. Tightned up the bass significantly but may change the overall CJ sound.Im sure there are much better caps than those out there now ,watch the physical size dem can get very huge!

And this also. Be careful what you wish for. I learned this lesson the hard way.

[earwig]

Even though I would not modify this newer model preamp that has already very good quality capacitors in it my old 1980s era Conrad Johnson pv 5 preamp did benefit greatly when I put in the mit Rel Caps ,the bloated sound tightened up, it was clearer more transparent imaged well and detailed and remained still some  warmth.I also put in much better quality nice gold rcas female jacks and silver wire at its inputs and used JAN military tubes. Reading a review of the later model  CJ Pv 11 I would say it resembled more like the sound of this later unit.I would say trying different brands of tube I could hear some sound effects of the tubes  itself too.