Cayin valve amp -tube rolling

I've just had a listen to my new Cayin MT-35 and am slightly underwhelmed. The mid-range isn't very clear and the highs aren't very high, a very "soft" sound.

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Playing Pergolesi's Stabat Mater wasn't very rewarding and the voices didn't have their usual clarity and range of dynamics.

Play the same CD through a Pioneer A400 (it was on the side as I'm thinking of selling it so have been listening to it) and it sounded much clearer, better mid and top and more "air".

The difference was like a veil had been lifted from the sound.

The Cayin has 1x 12AX7 (Sovtek), 2x 12AU7 (no brand) and 4x EL34 (Cayin Spark). Specs here.

My Shanling SP80s (which sound great- cheers Thorsten) use EL34s- can I swap them in to test or do I need to worry about biasing?

Are there any better tubes to try (without breaking the bank) that can add the missing dynamics and clarity to the sound?

Thanks for looking

 

Sovtek are generally pretty darn good, so I wouldn't bother changing your 12AX7's. From my own experience, Brimar 12AU7's are excellent (http://www.tube-shop.com/uk/prod_nos_detail.asp?ProductID=237&ProcessType=17) and Sovtek EL34's are very good - way better than the soft, soggy Chinese valves I was using. Try Watford valves for the EL34's.

You should get a significant improvement in all the areas you mention - I did, anyway. And if you want to tighten things up further and add some punch and clarity, valve dampers help a lot. I used EAT valve coolers on the input valves, but they are pricey.

Herbies Audio Lab dampers (http://herbiesaudiolab.home.att.net/) on my EL34's actually gave me too much tightness and punch for my tastes (!) so I sold them on. I'd recommend the valve upgrades, then the Herbie things if you want further improvements.

I found significant improvements with all of the above, i.e the changes were not small or subtle. There was no 'straining to hear the difference' it was just there.

Have fun .

 

thrudge, as you seem to know these things...I've got a pair of monoblock primaluna prologue 6's using the following valves :
4 x EL34 , 2 x 12AX7 and 2 x 12AU7, all "badged" primaluna, so probably like you say, soggy Chinese valves.
What do each of these do?
If i wanted to tighten or extend the bass, which valves need to be swapped?
The 4 small valves at the front ( the 12**7's ? ) all have cool dampers on them supplied with the amps.
Thanks, Neil.
(Sorry to hijack this thread...sort of !)

 

First off, I need to put my hands up and say that my amp/valve/general electronics knowledge is minimal. Anyway, here's what little I do know: the 12AX7's and 12AU7's are the pre-amp valves. These take the input signal from the source (CD player or whatever) and boost it up to a level where the power-amp section can handle it.

Your EL34's are the power valves. They take the signal from the pre-amp valves and boost it up to a level that can be used by your speakers.

Re your question about improving the bass, I've found that getting better valves brings improvements across the board - it won't be bass-specific, but it should make you happier. I'd swap the EL34's first.

What really deepened and tightened the bass in my setup was fitting a Border Patrol power supply (about £450 2nd-hand, contact Definitive Audio if you're interested). This improved pretty much everything else about the sound as well. Big grin stuff, worth every penny.

For a cheaper first step, you could try fitting the Herbie's ring things on the EL34's. Again, these had an effect across the frequency range, but the bass improvements definitely sound like what you're looking for. For me, they were a step too far; things were too tight, but that's very much a personal taste thing and I can quite imagine other people being very happy with the effect.

 

Cheers for the reply

Do you have any experience with KT77 JJ Tesla tubes, Mullard EL34 6CA7 - KT77 or Svetlana 6L6WGC or EL34s? Confusing, there seems to be "new" and "old" versions of several of them...

 

Changing my pre-amp valves (ecc82) from Jan-Philips to NOS Mullards has made a really REALLY positive improvement to my listening experience. In the past swapping output valves doesn't seem to have had such a noticeable affect for me (although to be fair I've only had to do it twice). Also, input valves are generally cheaper and don't require a re-bias, so easier to experiment.

BTW I have a pair of rather microphonic Brimar 6067's that someone can have a play with if they want. PM me if you want 'em anyone.

 

Many thanks. That's what I *thought* but wasn't sure. I'll start some investigations on dampers for the EL34's and maybe some tube rolling. Let the fun ( read expense!) begin

 

Change the AX7 and AU7 to Telefunken diamond bottom, best little valves ever- tightens up everything and much better treble.

For EL34 I'd always get Mullards

 

Hmmm, it seems they are extremely rare and soaring in value

 

Using KT77 in Primaluna Prologue One

Hi, I'am new to this forum and want to share my experience with the subject here.
Myself I was looking to get more punch out of my Prologue One (stock : Chinese EL34, 12AX7+12AU7). With the stock tubes the mids are nice but a bit too much in front, the trebble very nice and sweet, but the bass is a bit light for my taste.
My first try the SED 34 Winged -C- give a wonderful balance over all, much more clarity and precision, not so powerful gain as the Chinese but sweet sweet tube sound. With the SEDs the bass is more controlled, the mids feels less muddled and highs are very very nice.
Then tried the JJ KT77 (new reissue) replaced the 4 EL34 with 4 KT77. This makes a totally different amp!! Very sharp (almost bright in the first hours) in the upper mids and trebble, mids get further back and the bass is finally there : tight full bass and much deeper than I expected. The tubes are a replacement for EL34 but do not sound alike. The sound is clear not so much tubelike as one thinks, very fast transients, execellnt dynamics. Very good choice for Metal/Rock/ and Orchestral music. The level of detail in midrange is bigger than with EL34.
Myself I found the sound to analytic so I replaced 2 of the KT77 by 2 Chinese EL34 on each side. Well this could go wrong, but it didn't. Actually I have a wonderful balance now with mid, bass and trebble just real sounding. The trebble may roll off earlier I think and sound less sweet than with EL34 alone.
Of course with the adaptive autobias the tube swapping is easy, do not need to rebias. With the Cayin mayne you have to bias the KT77, although it is said the bias is same as EL34. The KT77 also seem to need a bit more current but with the Prologue One I had no issue as yet (I'm also listening at moderate levels)

To get a wider soundstage I replaced the 12AX7 and 12AU7 tubes with JJ ECC803 / 802 (Long-plate). They perform very well and the soundstage is now far more extended in width and depth.

Did anyone else have tried the KT77 instead of EL34, what was your finding ?

Cheers,

 

I use the Teles in the Prologue 2 and paid £5-£10 for used ones that will last years and years.

Get yourself to a Vintage Audio Fair.

 

It's not auto-biasing and Cayin haven't replied to my email about how to set the bias.

I've ordered a bias-probe from tube-town.de and a pair JJ 12AU7s and a Tungsol 12AX7 to play with.

From trawling the web on tube rolling (hopefully I'll be able to test this myself over the following weeks):

KT77 goes deeper and has slightly more powerful than KT66/ EL34s and replacing EL34s with KT77s will def need the amp to be rebiased.

EL34s can be replaced with 6L6, KT66 , 5881 and 350B tubes, all from the 6L6 family (any experiences of that here?), although as already mentioned replacing AU7/ AX7 tubes may have the biggest impact on sound.

Have also read good things about JJ E34L tubes and I'll keep my eyes open for any vintage audio fairs in the Midlands (where would I look to find out about these?)

I was wrong about my 12AX7 - it's an Electro Harmonix 12AX7 EH.

p.s. google loves this site: "tube rolling EL34s"

 

I wouldnt worry about changing the EL34 for a similar compatible valve.

I think you're doing the right thing changing the 'stock' 12au7/12ax7. This is where you'll notice the most difference.



As has been mentined, you'll get less benefit changing the output tubes.

 

OK, so lets say I'm going to swap the 12A*7's , do i need to keep to the same make tubes?
Watford valves have some "RFT" 12AU7's but they don't make 12AX7's.
Can i mix makers?
Any input on Sovteks?
Any recommendations?
I play more vinyl than CDs , and want a deep but tight bass (don't we all ) and not too bright.
My Veenas can be a little bright.

 

don't forget there is no valve that will make an oustanding amp out of an average one.... proven many times.

 

Yes you can mix makes. Try and get some matched Mullards, putting those in my amp made a serious improvement to bass tightness, and the treble is detailed but sweet. I got hold of two NOS mullard ecc82's for about £15 delivered, which is a bargain and a half especially given the difference they made.

 

Are you dissing my PrimaLuna's

 

not at all - i even didn't notice what you use - it's just a general remark

 

I wasn't wowed with the Teslas when I tried them. Better than the Chinese jobs, but nothing special. I'm using Svetlanas at the moment and I'm very happy with them - they put a lot more life into the music than the Teslas. When they go pop, I'll get more.

I haven't tried Mullard EL34s, but I had NOS Mullards in a previous amp and they were great. "NOS" is New Old Stock, i.e valves manufactured 20-odd years ago or more that have sat on the shelf and never been used. These have a justifiably (IMHO) great reputation, but can be ludicrously expensive.

I think I'm right in saying that 'new' Mullards are recently manufactured by a company in Eastern Europe who bought the Mullard name and machinery. Last I heard, there was a lot of debate about whether they were any good or not. I've never tried them, so can't offer an opinion, I'm afraid, although the large number of naysayers put me off.

 

I've just ordered 4 x RFT 12AU7 and 4 x Sovtek 12AX7 from Watford.
I'll let you know how they sound.
It seems the RFT's have been rebranded by many Audio companies, including Conrad Johnson, and I like their sound.