Stax SRM-006T plus Kimik or new SRM-323S

[Martyn73]

Hi,

 

I recently bought a used SRM-006T to power my SR-404 headphones. The amplifier seems to be working fine and it has the stock 6CF7 tubes. Sometimes I notice slight distortion when listening to fast paced electro music and Souvenir by OMD. I'm not particularly attracted to the idea of tube rolling but I think I should get the SRM-006T serviced soon and I've been offered the Kimik upgrade for £200. This is a lot of money and I'm starting to consider getting a newer SRM-323S or 323II to replace the 006T.

 

I'm not sure whether to service/upgrade the 006T or get a new and cheaper to run solid state 323. I did try SR-407s with a 323S and noticed that the mid range was harsh but the SR-404s are noticeably smoother so the amplifier may not the issue. I'd be grateful to read your views on the tube v. solid state debate as far as Stax is concerned. Having read many reviews on the 323 series there doesn't seem to be any negative comments but Innerfidelity weren't especially complimentary about the much more expensive 727II amplifier. I've chatted with a few engineers and aren't convinced about the merits of tube amplifiers for electrostatic headphones but honestly I don't really understand the technical explanations.

 

Cheers,

 

 

Martyn

[DefQon]

What is the Kimik mod?

 

I like my 404's with my 323S. The 006 is not bad and evidently built upon and based off the T1 and for me it matched the 202, LNS and Lambda NB superbly but did not sound so great with the rest of the Lambda family and O2's. 

[nikongod]

 I've chatted with a few engineers and aren't convinced about the merits of tube amplifiers for electrostatic headphones but honestly I don't really understand the technical explanations.

 

 

Whats not to like about tube amps for electrostatic headphones? 

The only thing I can think of is that tubes need replacing every few-thousand hours? Big deal. A few dollars spent on tubes ever other year. Instead of going to that jazz club you have a nagging feeling is too expensive, don't. Once. Or don't buy 3 new records and its even. 

 

Nit-picking

Almost any STAX amp you will ever see with tubes in it is a hybrid. Its sort of worth note. 

 

 

Anyways. 

First rebias the amp. Or Bias the amp, as the case may be. There are instructions on Head-fail. I cant be bothered to find them. 

 

If you have already done that try different tubes. I'm also not a tube roller, but tubes do wear out eventually.... New tubes should last like foreverlong. Years of average use. 

[spritzer]

The Kimik mod is a bad joke.  Take some NOS tubes (not the good ones), a tube cooler which isn't needed and then it is "properly adjusted".  Now the thing about the Stax amps is that their power supplies are completely unregulated so once the line voltage changes (which it will) those adjustments are no longer accurate. 

 

The distortion you are hearing when the amp is stressed is due to the amp design simply not being to swing enough voltage.  The SRM-323 is better in this regard but it sounds a bit thin.  Just the nature of the beast as Stax had to build it to a price. 

 

Tubes are high voltage, low current and low output capacitance.  Electrostatics are high voltage, low current and low capacitance so the perfect pair. 

[Martyn73]

The Kimik mod is a bad joke.  Take some NOS tubes (not the good ones), a tube cooler which isn't needed and then it is "properly adjusted".  Now the thing about the Stax amps is that their power supplies are completely unregulated so once the line voltage changes (which it will) those adjustments are no longer accurate. 

 

The distortion you are hearing when the amp is stressed is due to the amp design simply not being to swing enough voltage.  The SRM-323 is better in this regard but it sounds a bit thin.  Just the nature of the beast as Stax had to build it to a price. 

 

Tubes are high voltage, low current and low output capacitance.  Electrostatics are high voltage, low current and low capacitance so the perfect pair. 

Hi Spritzer,

 

Thanks for replying. You probably saved me a lot of money! I've since read that the Kimik mod involves Philips 6CF7 tubes so I'll try to find a matched pair of RCA Clear Top tubes in the UK to replace the existing tubes. At least I can certify that the 006T has been serviced if I decide to sell it. The existing tubes seem to be working OK but I didn't notice harshness in OMD's Souvenir played through a HD 650 and a cheap Bravo Ocean tube amplifier. I'm starting to think that solid state may be easier and cheaper to live with.

 

Does the SR-404 have a harsh mid-range with a 323S? I briefly owned a SR-407 with a 323S (both returned for various reasons) and I noticed that vocals could sound slightly harsh but this may have been due to listening to an MP3 of indifferent quality.

 

Many thanks,

 

 

Martyn

[Mr.Sneis]

I felt with the 407 and 323s that vocals were also slightly harsh but nothing I couldn't handle.  The LNS and 323s on the other hand match up very well (also ESP950).  The 007 and 323s sound like crap to be frank.  I think the bottom line is the 323s can sound great with the better regarded (older) lambdas, just don't expect the world from it.

 

There are some people that really dislike the 323s by the way and would probably prefer the 006t so it's anyone's guess but best to hear on your own.

 

I had the 007tii for a while with better than stock Japanese tubes and it was OK but I like the 323s better.  The 006t probably had a similar sound?

Edited June 13, 2014 by Mr.Sneis

[spritzer]

I'd class both the 404 and 407 as harsh though the 404 less so. 

 

The stock tubes are probably fine but it's the tube type that is unfit for the role.  Not much else out there though that can replace it.  The ECC99 can be fitted with some mods. 

[Martyn73]

I'd class both the 404 and 407 as harsh though the 404 less so. 

 

The stock tubes are probably fine but it's the tube type that is unfit for the role.  Not much else out there though that can replace it.  The ECC99 can be fitted with some mods. 

What's the ECC99? I tried searching but to no avail.

 

I've found that decent tubes such as Cleartop or GE are difficult to get in the UK and wonder if in the long term servicing is going to be a problem. Hopefully, the 323S will be tolerable with vocals with the SR-404. Female vocals were irritating with the SR-407 and 323S and the combination of the SR-404 and 006T seem to reduce this problem. My torture track (which caused me to begin to hate my Sennheiser HD700), Slow by Kylie Minogue which is usually sibilant, is acceptable with the current Stax gear.

 

Is it normal to hear a crackling noise in the left earspeaker when the 006T is cold, say a few minutes after turning on? Oddly, with an MP3 playing with the 006T set to zero I can still hear sound so this should be fixed on servicing.

[grawk]

http://bit.ly/1lixdO2

[DefQon]

I'd usually go with the original Japanese made Matsushita tubes for amps such as the T1 family and maybe the 006 as well as they are for me at least better sounding then the cheap RCA's you can buy.

 

That Kimik mod sounds like a scam, 200 quids for that?

[spritzer]

Mp3's... really???  Stax requires a top end source (not expensive, just good) so any harshness could easily come from there.  That and the mastering on most newer recordings is awful which doesn't help matters. 

 

What ever you do, don't buy ECC99's and stick it into the amp as it is now.  It will destroy it. 

[Martyn73]

Mp3's... really???  Stax requires a top end source (not expensive, just good) so any harshness could easily come from there.  That and the mastering on most newer recordings is awful which doesn't help matters. 

 

What ever you do, don't buy ECC99's and stick it into the amp as it is now.  It will destroy it. 

I'll have to sort out the source soon. Do you know of any custom made electrostatic energisers?

[Martyn73]

I'd usually go with the original Japanese made Matsushita tubes for amps such as the T1 family and maybe the 006 as well as they are for me at least better sounding then the cheap RCA's you can buy.

 

That Kimik mod sounds like a scam, 200 quids for that?

I called a valve supplier and the only explanation for cryo treated tubes sounding better was that they wouldn't sell them otherwise which is not a ringing endorsement. Taken at its highest, you may get a slight improvement but for £130 more than the cost of a normal service which would include the stock tubes which at least would keep the 006T within factory specification.

 

I can't help thinking I would be happier with a solid state amp. The 727 is beyond my budget, but the 323S has to be better than a 252? Both the 252 and 323S are three stage I understand.

[Voltron]

Then shut up and buy a fucking solid state amp. We don't care to agonize about it with you. And there is no reason to invest in your 006t if you're going to sell it. Just fucking sell it.

/stupid thread

[DefQon]

Well of course you're going to get a positive response about the wonders of cryo tube improvements when you call a tube/valve supplier otherwise they wouldn't be making money, a profit if they gave you the opposite response.

 

The 717, 727 (both stock and with mods) are the best of the Stax SS line up of amps. The 323S is also fairly decent for what it does and the price it is at.  Better then the X Pro, XH, 212, 252/S family. 

[morphsci]

Save up and buy a 727 and STFU!

[Sherwood]

1) It is clear that you will not be staying with one amplifier (or pair of headphones) long, certainly not long enough to warrant replacing tubes. Whether it is "cheaper to run" seems like a ridiculous metric, then, as you'll only replace them in search of a different sound.

2) There is no good reason to use "souvenir" as a test track. It is terribly recorded, and not indicative of the true performance of any piece of equipment. That you mention it by name is evidence that you should spend more time listening to your system before agonizing about it. Unless you're designing a system specifically to play Souvenir by Organized Maneoueuouevres in the Dark, in which case you should leave now.

3) You almost certainly don't need new tubes. You need to learn how to bias an amp. Look here: http://www.head-fi.org/t/415385/tube-change-biasing-a-stax-006t-ii

4) You're right on the edge, here. Please read your welcome message again, and dwell upon it.

[spritzer]

Cryo is bullshit with some basis in reality.  The crystalline structure of metal is a factor for some uses and for stuff like margarine and chocolate it is critical.  How that would matter to tubes, cables, headphones etc. is beyond me though.  Especially the tubes which will reach 150°C and undo what ever changes might happen when you cryo treat the metal.  Utterly absurd stupidity. 

 

Plenty of DIY Stax amps but no commercial units this cheap. 

[CraigBuckingham]

New to the forum. Are you just talking about swapping boxes or is this a technical forum where you guys don't mind getting your hands dirty and want to fix up some of the compromises inside?

Bit of background, I had an SRM-313 SR-404 combo and a friend’s set of AKG-340 dynamic headphones (circ 1989) he picked up from a garage sale for $10 were kicking the butt of my Stax set-up. I was pretty disillusioned to say the least.

 

I spent quite a bit of effort redesigning the power supply of the amp, (custom chokes, Jensen electolytics and a few other things) to have it finally jump a little bit ahead of the AKG-340. For me it wasn't enough to justify the expense so I put it back to standard, keeping all the good parts and put it up for sale on eBay. Got close to my money back as I bought direct from Japan at a good discount so it wasn't an expensive exercise.