Amp upgrade with Canton speakers: Feasibility study

[Asit]

Hi folks,

It's more than a year ago, I started this thread for my amplifier search. Now, 9 months after receiving my Leben CS300 tube integrated amp (12 wpc, Class A push-pull, EL84 power tubes), it's time to resurrect this thread, may be, for one last time, to update you with a few issues and seek your suggestion on something.

First, let me seek your suggestion on possible tube rolling.

Firstly, does one tube-roll only the power tubes (in this case, a matched quad set of Sovtek EL84)? Or, should one try changing other tubes as well? The driver tubes are a matched pair of GE five-star series 5751.

I have done some searches for the power tubes. The NOS (New Old Stock) Mullard tubes are supposed to be magical. However, they are nearly impossible to find. If you manage to find a matched quad set, they are USD 250 or so per piece (that is, USD 1000 for the 4 tubes). I am NOT going to spend that kinda money on extra tubes.

Based on reviews on net I find Gold Lion reissues (about USD 110 for 4 tubes) and JJ/Tesla tubes (about USD 42 for 4 tubes) to be the best possibilities for EL84 tubes. In addition, our forum member Rajiv suggested locally available BEL EL84 tubes in this thread right after I got the amp.

I need your help in making a decision for the selection of the tubes, and also what is the best and most reliable place to get them from.

Also I am concerned about comments like the following (usually found in sites selling these): "Note: These tubes have a slightly larger diameter than other EL84 tubes so they can not be installed into some Marshall DSL201 or DSL401 amplifiers, some reissue Vox AC15 amps, and Bad Cat amps."

Can somebody confirm if any of the tubes I have selected above would / would not fit into my Leben because of possible size issues?

Should I need to keep some stock of the driver tubes as well? Folks, please help.

I shall update with my new listening experience in a separate post.

Regards.

 

[odyssey]

Hi Asit
A different take from me - rather than asking which are the tubes to go for, I would suggest you ask yourself what you are missing (or would like more of) in your sonic signature - is it better freq extremes, better bottom end, better transparency in the midrange, microdynamics (last two is where the Mullard EL-84s excel at)...etc and then figure out which tubes work best for this

The tubes dont need to be a matched set

cheers
Sridhar

 

[Rajiv]

Hi Asit,

The driver tubes in the Leben are very good.

As Arup says Leben has done a good job.The GE five star 5751 are as good as they get.

As for the EL84's I would say that the Bel tubes are very close to the Mullards.

The Sovtek are also OK.

You could try the 7189 tubes.This is the same as the EL84 but can handle a little more volage on the plate.These tubes have a nice punchy sound.

The Russian version of the 7189 is the old Sovtek EL84M . The Russian number is 6P15P-EB or 6P15P-EP.

Does the Leben need to use only matched sets of tubes?

If you dont need matched sets I can send you a quad of BEL EL 84 tubes.I have only a emmision type tube tester so I can check only for emmisions,but cannot match the tubes exactly.

Regards
Rajiv

 

[Asit]

Great! Already 3 replies in an hour. Thank you very much for your opinions. This is an area I know nothing about, and hence any help would be greatly appreciated.

Audio_engr, The JJs go well in the Leben. However, some reviewers find the Sovteks better. The JJs are quite affordable and well-built.

Sridhar, I am actually not missing very much sonically. After the Cantons were put on the stands, all the relative shortcomings have been met very satisfactorily (basically, they were earlier lacking a a bit in the bass department and lacking a a bit in openness, as I commented in Mahiruha's valve amp thread). Recently I heard a few very good and expensive installations in Bombay, and in comparison my modest set-up is doing amazingly well, to the extent that I am surprised too. More on that and some tweaks I have tried recently later.

The reason I want to tube roll now is not that I am missing something, but to have the whole tube experience by rolling the tubes and at the same time keeping some tubes as spares.

Sridhar, what do you mean when you say I do not need matched quads? Do you mean I do not need a matched quad set, but I need 2 matched pairs, or do you mean all four are not matched to one another. I am sorry, but I am a complete noob in this business. Can you or somebody explain why one would need a matched pair or a matched quad, and how does one detremine what one needs?

Rajiv, my sincerest thanks to you for offering your Bel tubes. Let me find out first if I need matched tubes. I have read about the old russian EL84M, and construction-wise people say the Gold Lions are the closest to these EL84M's. As I said, I am NOT aspiring to get the NOS British Mullards.

Now on the GE 5751's. Okay they are good, as everybody is saying. However, don't I need to keep some as contingency?

Regards.

 

[odyssey]

No need to match the tubes - none of the 4 need to be matched.

cheers

 

[arj]

Hi Asit,
I would second/third all of the above. Tube rolling can be fun, $$$ and slightly unpredictable!!

it is better to try out the BEL as suggested by Rajiv. Another option would be to try the russian equivalent ie 6P14P (usually made by reflector). they usually sound Much more cleaner than the more expensive NOS
Problem with Tube rolling is that it can be addictive and at the same cause more of sidewise lateral-grades rather than upgrades !

So makes sense to first identify your areas of relative weakness and then do the research.You could post out in the audioasylum tubs forum and get some insights on other tube rolling experiences.

But keeping a contingency tub is a VERY good idea...evn if you do lose on tube..waiting for a replacement can be a very difficult experience so do try out the BELs..they will give you that backup If they work for you.

Sridhar, I did not know that the tues need not be matched. is it because the Leben design is Autobiasing ?

 

[Asit]

Hi Sridhar,

The Leben user manual does not say anything about the tubes being matched. However, all sites selling the Leben amp proclaim the power tubes to be a matched quad (and even the driver tubes to be a matched pair). Now, I am as inexperienced and uneducated in this business as they come. I need some help here. Can you or anybody have some explanation here on this tube matching business? When is this needed and when not? Is this related to biasing, as arj has mentioned? What is auto-bias? Boy, I am at a loss here. But I am willing to learn with a bit of help.

Hi arj,

Thanks for your input. I am going to give the BEL tubes a try for sure, just trying to understand and making sure the unmatched tube thing from Sridhar before that.

Regards.

 

[hifiashok]

a pull from the cadence va1 description (for the auto-biasing Q)

Cadence VA 1.0 Design

The design of the VA 1.0 is completely unique. Solid state transistor circuitry drives the valves. Specially designed solid state devices also monitor and constantly bias the valves, so that they are always matched to perfection. This makes the VA 1.0 the most user friendly valve amplifier available. There is no need to match valves, any valve may be replaced without having to change the whole set. Plus, bias control is automatic. Just switch on the VA 1.0, and play.

 

[gobble]

Hi Sridhar,

The Leben user manual does not say anything about the tubes being matched. However, all sites selling the Leben amp proclaim the power tubes to be a matched quad (and even the driver tubes to be a matched pair). Now, I am as inexperienced and uneducated in this business as they come. I need some help here. Can you or anybody have some explanation here on this tube matching business? When is this needed and when not? Is this related to biasing, as arj has mentioned? What is auto-bias? Boy, I am at a loss here. But I am willing to learn with a bit of help.
.

I was trying to find the same answers this weekend to roll tubes for my new preamp. Tube Matching Demystified

I believe in a push pull type amp the L+R gain may be mismatched but it does not matter for a preamp section.

Regards

 

[Asit]

Hi Ashok and Gobble,

Thanks for the help. Let's see how I can use the information you have provided to farther my understanding on this need (or lack) of tube matching. Gobble, thanks for the article. I have browsed through it, but yet to give it a serious read. My current understanding is that the driving tubes should not need any matching, and hence for a pre-amp you probably do not need to worry about it (at the same time this statement if correct makes me more confused because many sites giving the Leben CS300 specs have the driving tubes as a matched pair, cannot really understand it).

Regards.

 

[gobble]

Hi Ashok and Gobble,

Thanks for the help. Let's see how I can use the information you have provided to farther my understanding on this need (or lack) of tube matching. Gobble, thanks for the article. I have browsed through it, but yet to give it a serious read. My current understanding is that the driving tubes should not need any matching, and hence for a pre-amp you probably do not need to worry about it (at the same time this statement if correct makes me more confused because many sites giving the Leben CS300 specs have the driving tubes as a matched pair, cannot really understand it).

Regards.

Only the output tubes need to be changed I believe. Anything else will not affect SQ. Correct me if I am wrong but changing output tubes for preamp should make a sonic difference - assuming an integrated has the signal going from output tubes of a pre section to the power.

Regards

 

[arj]

Asit if you get a chance buy a matched pair/quad..else let it be ie buy it unmatched

my own findings
-the preamp tubes also do make a difference although small
-power tubes make the most of the difference. I loved the Russian Reflector tubes and as per discussion on AA they are preferred over NOS.

if you want to buy from the US and get it shipped..Cryoset Online Store is a good site and they have the Reflectors as well.

 

[sidvee]

Asit if you get a chance buy a matched pair/quad..else let it be.

my own findings
-the preamp tubes also do make a difference although small
-power amps make the most of the difference. I loved the Russian Reflector tubes and as per discussion on AA they are preferred over NOS.

if you want to buy from the US and get it shipped..Cryoset Online Store is a good site and they have the Reflectors as well.

If Arj was referring to power amp tubes making the most difference - I will second that - I have found 3 different versions of KT88's in my push pull amps - all sounding different - and I prefer the EH version.
Cheers,
Sid

 

[odyssey]

Hi Asit
All Leben amps are self biasing. They do not need any tubes to be matched. In reference to the EL84 tubes here, you do not need to spend more to get a quad matched set, they will just work out expensive.

Cheers

 

[ajay124]

I spent the whole of January and February trying to decide which amp to buy.Since I had opted for the Dynaudio Audience 122 speakers,I wanted an amp with minimum power handling of 120 WPC at 8 ohms and priced less than 100 K .I finally settled for the NAD C 375 BEE at 80 K and am satisfied with the decision.Other option were Creek Evo 2 - 80 WPC at 49k or the earlier EVO 1 FOR 42 K.Roksan Kandy Mk 111 -120 WPC 35- 40 K in the grey market.There is a Quad 909 going for app.50 K in the Hifivision classified.If you can locate a used or grey market Quad pre for around 35 - 40 K it would be a great set up.Rega Saturn and Arcam FMJ 28 /38,Primare 21/30 are all expensive/overpriced?Creek has launched a new integrated amp the EVO 5350 -120 WPC which the Indian dealer said would be available in the first week of March.Price app. 85 K.

 

[Asit]

Gobble, not quite sure how to respond to your point here. My understanding is still pretty poor. Let's see if others say something.

Thanks Arj for the link for sourcing the tubes. Thanks Sid for sharing your experience too.

Sridhar, thanks for clarifying that at last. I have to get hold of cranky to help me understand that self-biasing thingy.

Regards.

 

[prem]

Hi Asit

Why don't you just write to Leben as to whether the tubes need to be matched or not? The designer might even recommend a few tube options.
According to Jeff Day, the Gold Lion EL 84 reissues are highly recommended. I think his ears can be trusted.

 

[viren bakhshi]

Hi Asit,

The input tubes in the amp are voltage amplifiers, running in Class A conditions, and in a very linear range. As such, their variation in current is minimal with input signal. So, matching is not necessary - but can be benefitial if you want exact balance to be maintained within the channels.

The output stage is more of a current amplifier - the current swing is large. The weakness of a pushpull stage is that there are two tubes handling opposite phases of the output, and that there should be no residual DC current flowing in the output transformer. How much residual DC can be tolerated depends on the design of the output transfomer - it's of the order of 5 mA max. That means matching of the tubes in each channel (a pair).

Self biasing in the output stage means that the two output tubes' cathodes are tied together through a common resistor to establish the bias voltage. This helps linearise differences in the tubes to some degree. Matching is very benefitial still.

I also suggest trying the BEL EL84 tubes. They are very good. My understanding is that BEL got equipment from Mullard to manufacture these tubes in India, and they were often sold back to Mullard and Philips under their markings.

Regards,
Viren

 

[Asit]

Hi folks,

While the discussion is on for the tube-rolling, here I want to share my recent experiments with a few tweaks I have tried in my set-up.

Ashok's (hifiashok) post (http://www.hifivision.com/amplifier...-speakers-feasibility-study-52.html#post95532) in this thread regarding my rack got me thinking. He was commenting on upgrading my rack, after the speakers were placed on such aesthetically and functionally wonderful stands. I knew my rack did not provide proper isolation/damping for the sources (CDP and Cassette deck) and also for the valve-amp. I know all valves (even the best built ones) would have some microphonics (undesirable transformation of mechanical vibration into noisy electrical signals, however small) and that an isolating/damping platform was essential. I had a few private exchanges with Ashok on vibrapods and such isolating equipments. I did an extensive net-study of these things, but in the end was left with a mixed feeling. Moreover, these are not the cheapest tweaks, and did not want to buy them without trying out. Nobody I knew in Kolkata had them.

One distinguished forum member suggested I tried out unpolished marble slabs under the amp/CDP since a few of his friends had good results with such tweaks (ideally the marble slabs should then rest on cones). He was due for a visit at my place and when he came, to my surprise brought along a small marble slab just big enough to be put under the feet of my CDP/amp. I have had 3 racks before, at least two of these were very decent (bought abroad from hi-fi gear stores) and never really worried about these things before in my life. So frankly, I did not know what to expect. When we put it under my amp and everything was turned on, lo and behold, there was a marked change in the sound. The sound became more focussed (more PRaT), for lack of a better word. We also tried the slab under the CDP. However, although initially I liked this for instruments alone, I did not like this arrangement with vocals which got receded noticeably with respect to other things. I invited another distinguished forum member for a listen and he also agreed. Then I got another similar slab (call me mad or completely crazy or whatever, but these are quite inexpensive, Rs 100-150 for a slab) and we tried all possible combinations, and ultimately settled for both the slabs under the amp.

I thank these distinguished forum members for their help as always. Folks, these people have solid shoulders on which their heads rest, but this time they had to go with my madness a bit and play on, I suppose. Any way, I am happy now. The only reason I am not revealing their names here is because I do not want them to be made fun of as was done in a thread where some tweaks were discussed in the past. I have revealed Ashok's name because he openly has recommended isolating accessories in the forum. I hope he does not mind me taking his name here.

Anyway, I now believe letting any unwanted vibrations die out is a must for a tube amp, and perhaps also very important for source equipments. We are discussing a tube equipment here, the build quality of which has been praised by everybody in the world. Hence I'd consider it a must for all tube based gears. I have used only crude methods here and am not going to try too much I suppose, but it was a revealing experience for me. When we move to a new apartment next year, I'd definitely think about a new and nice rack (but not too expensive, one I'd be able to afford easily) which would pay attention to the issues discussed here.

Regards.

 

[odyssey]

@Prem, my info is straight from Leben
@Asit, if a matched set costs you just that bit extra, sure go for it.

Cheers