Which tubes for CT5 preamp? Sovtek or Electro Harmonix?

[artemus]

I'm a recent CT5 user. Absolutely love it. I know the 6H30P is not a popular tube for some. I have the EH in it now and need a backup. I looked at the DR variant but $300 per tube is outta my league. So which one? EH....or Sovtek. I like the EH. But I have read that Sovtel is preferable to some. OK, so which one? Thanks

[roberto]

Hola Artemus,

When I had my CT-5, I did use this brand and I did had excellent results. Perhaps out there might be a better tube, and also are more expensive...I did like a lot what I got. Bass control was one thing that I do remember.

https://www.thetubestore.com/electro-ha ... h30pi-gold

Happy listening!

[Big Dog RJ]

Definitely Sovtek!

Even on my previous ACT2, I first used the EH tube's, they were OK... Then switched over to Sovtek and superb results. Transient control and speed were the two main factors I noticed straight away. Few years after, now using a fully upgraded CT5 and Sovtek as well.

Tried all the fancy EH gold pins etc., but nothing quite matched the Sovtek sound. I guess it's a sense of balance and finer detail that these tubes provide. When partnered with the right power amps, the control factor in the speakers is realised straight away.

Unfortunately pricing in Aus is nearly double compared to the US but I'm willing to pay that extra simply because the CT5 deserves it.

Cheers and enjoy the music,
RJ

[ajf75]

Welcome Artemus, congrats. I'm also a happy CT5 user with no plans to move on.

I'll agree that those tubes sound different. For example the EH were not good with EL34 power tubes - too much of same qualities IMO. OTOH, they were pretty good in many areas when using KT120 power tubed amp, but felt the EH still gave up too much in the areas BD mentioned (control and speed), so I am back to the pricey DR tubes that IMO are slightly nicer than the sovtek's. I cannot justify the price of the DR tubes relative to the subtle differences from the standard sovtek- but I find it good practice to avoid justifying any audio hobby expenses

Hey Big Dog, have you ever posted the details of the "fully upgraded" aspect of your CT5? I'm very curious!

[Big Dog RJ]

G'day AJ,
Ah! The upgrade on the CT5... I get asked this quite often and try to minimalise my answer to other Audiophiles using other brands but to CJ owners I will list it out as follows:

1. Full cap upgrade to All Teflons, no poly-props, no electrolytics, nothing left untouched here. It's like the TEAMax2 phonostage, upgraded with a full array of Teflons.

2. All resistors are Vishay and Metal foil types in all critical paths of each signal and power supply stages.

3. The input and output terminals have been upgraded to that used on the GATS2, plus internal layout of signal paths have been further minimalised, to create shorter signal paths from each input, then directly onto the output stage utilizing the shortest possible wires.

4. One more costly upgrade was done on the transformers, again same used on the GATS2, multiple EI-core transformers were installed and replaced.

5. Extra heavy duty copper grounding plate was also put in place under the chassis inorder to protect from further grounding issues, which I had previously experienced with my ACT2.

These major five upgrades were done over a period of time, one step at a time. I purposely did these custom upgrades simply because I wanted to have less maintenance issues with just having to replace two tubes compared to four on the ACT2, and I believe the Sovtek 6H30P's can outlast the 6922's that are used in the GAT. What I have done internally to this CT5 is a radical complete overhaul but by just looking at it from outside you cannot tell. Only when you pop the hood and lift the preamp, you will notice the added weight, which does make a difference. In all these upgrades made so far, the level of improvement is 45-50% over than the standard CT5, and the added cost of parts nearly equals the GAT. In which case many have told me just to go for a GATS2 or at least an ET7S2. Although that would be nice, neither of them are quite like what I have managed to get out of this particular CT5.

*there's one more very very special upgrade* which I have kept a secret for quite a while but since you asked...
When I had that wonderful limited experience with the Kondo Audio Note Kogaru monoblocks, I noticed that the internal wiring, point to point, were all pure silver contacts. Damn expensive! And that's all she wrote!

When the upgrade/s were completed, my good mate said that I'm "insane!" but the sound is phenomenal, along with the control factor it delivers driving the monoblocks. He also said that if ever wanted to sell this thing, my investment is lost and no one would understand my rationale behind such an upgrade. He then later commented that if I did ever want to sell it that he'd gladly take ownership! I said that's good to know but I'm keeping it, as this is my final preamp, plus I just love the stunning look of it as well.

It does take a while to warm up, in fact quite a while... About 2 hours, around the 3hr mark it just takes off like no other! That's when I've either melted into my seat or the musicians are sitting around me, enjoying the company and ambience of the social setting, whiles the performance is live.

I've also carried out a very similar upgrade on the monoblocks - LP125m's. In fact all of the above have been completed, except the replacement transformers and point to point silver wiring /contacts. This is going to be a very costly affair, which I will do eventually. At the moment I'm completing a few things on the house, so our priorities slightly adjusted...

Again I've had extensive experience with the ART300's, LP275m's and the original ART monoblocks. I noticed the most significant aspects are high effortless power ratings and plenty of raw current on tap, capable of griping any full range stats with an iron grip, no flinching one bit, even under heavy impedence swings.

My final plan is to modify the LP125m's to an all out Class A power amp, based on the high voltage rails by adjusting the bias on each output stage. This would deliver a solid 125w AB, plus an additional 80-100w on Class A. At the moment, I've got them slightly modified where each monoblock provides 60w of Class A bias, and you can very easily feel the sheer speed, grunt and tightness in bass control, it's doing a superb job controlling the CLX's. Whether or not I would really require more power on Class A, I'm not sure but one thing is that it's very different to the normal Class AB switching in push-pull layout. Once you experience it and used to that 60w Class A control and clarity, it's very hard to go back to the norm. Of course when the power amps are opened up further, then its Class A bias switches over to Class B but I've never gone towards that territory as yet... 40-60w on Class A is pretty loud enough for my delicate ears...

Cheers mate, just keep this to yourself...
RJ

[artemus]

Thanks for sharing that BD RJ. Wish I had the ability to do those upgrades.

[ajf75]

Big Dog, wow! Not what I was expecting at all! You certainly do have a fully/radically upgraded CT5... and I congratulate you on being so brave. I also really appreciate you taking the time to provide all these 'secrets' .

I don't know what I'll do with this info, but I'm certainly a believer in such tweakery, so will be considering what you've done - we'll see when I get the bug again.

In my personal experience, the equipment tweaking I've done always resulted in audible changes, but usually left me struggling with whether it was truly better or just different - then requiring experimenting with different cables/footers to re-balance the system's tonal harmony and then ultimately decide if there is real net gain. Tedious at the very least for an OCDer! To minimize this, I'd say for anyone, its important to have good clarity on what your sonic goals/expectations are before venturing, but it seems you certainly would have this advantage from all the gear you've had access to.


Best of luck on your modding ventures with the amps as well towards more Class A power - also really interesting to hear about.

[Big Dog RJ]

Since this post was focused on the CT5 and the best possible tubes to use, as previously mentioned by fellow forum members, it's a very "personal choice" on what tubes you prefer. Therefore, by all means you would have to try a few different brands and focus on what you're after. As long as the type of tube is not altered, the brands can be chosen for that perfect sound you prefer.

Speaking of "personal choice" my all time favourite preamp is the original ART preamplifier. At the time, partnered with the Premier 8A monoblocks driving the Apogee Divas, I did get the opportunity to upgrade the ART to a series three but I didn't go ahead. Perhaps it was due to running a dealership and hence I had to make ends meet, therefore we used the ART as much as possible until we found a special customer for it.

If I was able to keep the ART then I would have proceeded with all these upgrades / mods, and that would have been one phenomenal preamplifier.

Fast forward over 20 years, having gone through the ACT2 for a while, and the GAT for a limited time, I was still looking for a particular type of personal sound that allows me to fully engage in the recording and immerse myself in the performance, appreciating every effort each musician is putting into their artistry. As time went by, I found myself going back to that golden glow, the special coloured caramel sound that CJ was known for. I started heading towards the PV12, then a PV15, the Classic preamps, both the SE & Classic 2 versions, and finally settled on the CT5. My rationale behind this particular one is based on the following:
1. Near ACT2 performance
2. Less tubes to maintain
3. Accessible upgrades based on SE version- Teflons, Vishay resistors & metal foil caps.
4. Further upgrades are manageable due to single chassis - point to point silver wiring, and transformer upgrades.
5. Taking experiences from other top line preamps, such as kondo Audio Note, Lamm Audio and CH precision, I was able to get a glimpse of how these far much costlier preamps are designed, and installed a handful of these items into the CT5 to experience the improvements... The end result was an improvement of over 50% in performance ratio compared to the standard.

The other thing I experienced with monoblocks is that unlike a stereo power amplifier, the preamp has to be able to adequately control both channels of power amplification. Each monoblock operating on its own, driving only one speaker, is supposed to do just that, however if the preamplifier cannot fully control the power amp, it will not have that overall grip on the speakers, plus overall musicality also suffers.

When I first heard the CLX's, I noticed that most power amps used were operating in Class A mode; Pass Labs XS300 series, the XA30.8, Ayon 400's, Dan D'Augostino Momentums & Relentless Class A, sounded superb! Big tube amps, such VTL, Manley Lab's and ARC, also sounded excellent operating in Class AB. This is where I got my idea keeping the total power output within reasonable limits, 125w/ch, which is more than adequate to drive the CLX's to their full potential. Converting more of the Class AB towards Class A in push-pull config.

The goal is to achieve that finer balance of ideal Class A operating bias, not too heavy on the higher grade voltage rails and voltage regulator power supplies, not overpowering the amplifier into thermal overload and adjusting the output based on the speakers sensitivity and impedence curve. This is the key to achieving that finer balance otherwise many parameters can go awfully wrong, ending in transformer overheating, resistors going off and caps going into DC off-set, virtually ending up in power amp shut down...

Therefore, although these upgrades can be done on any model by anyone who's well versed in electronic engineering, it takes a specialist who is well versed in audio engineering and recorded music, who will understand these sort of upgrades and advise you the best possible route to take, if you want to achieve a personal choice of sound. This was the first message / advise I was given by legends whom I met personally:
Nelson Pass, Bob Carver, Eve Anna Manley, Luke Manley, David Manley, Gayle Martin Sanders, Arnie Nudell and the legend himself, Dan D'Agostino. Of course there were a host of others, like Jim Winey, Peter Walker, Franco Serblin, our great mates messers C & J, whom I also learnt a great deal from. My only regret is that I never had the chance to meet Mr. Kondo San, the founder and believer of kondo Audio Note. Anyway, after nearly 25 years I managed to carefully install each of these items / components into the CT5, and I believe this is the best I could possibly do to the highest point, in order to achieve a special personal sound from the CT5.

There's one more very special item I would like to add, however this will change the overall sound of CJ itself. That item is the KSI capacitor designed and made by Kondo San. These are very expensive, even more than the Duelands & Mundorfs but their sound and what they can do is simply phenomenal. I'm still pondering but I'm not sure if I'll be getting anything from an original CJ sound, in fact I might lose it altogether... So due to that doubt, I'm holding off. I guess this is as good as it gets.

I was also planning on following the same exact procedures in the monoblocks but since this is two chassis, things can tend to be quite expensive. So I guess one step at a time. In summary, what I focused on was total control over the monoblocks, which in turn fully grips the CLX's with its Class A operation upto a certain range and keeping the original recording from the primary source as close as possible, all of which must be close to its purest form, without any added artificial enhancements. And that's the main reason why I don't use sub woofers!

Experience as much as possible from live events, talk and engage with the experts, the designers and manufacturers individually, learn from their success stories and failures and draw up your own conclusions and findings. At the end, you will find your special type of sound and achieve that total synergy, once you've got it right, there's no turning back! Just enjoy the music,
Cheers, RJ

[ajf75]

Big Dog, another worthy contribution to the site for us all to reference - and further ponder the question of do I dare with my cherished CJ gear ...

thank you