Stax SRM-006tII and SRM-006tS - differences?

[reaction]

Hello,

Does anybody have any clue what are the differences between SRM-006tII (2006 model) and SRM-006tS (2010 model)?

Thanks a lot

 

[csl67]

The SRM-006tS, I’m quite positive, was made because many parts from the previous model were becoming obsolete or never made. A word of warning: Stax does not sell their modified dual concentric pot made by Alps as a spare part and neither does Alps, so I have a pretty much scrap T1s for a while. so for that reason I would try to lean toward a newer unit on that circuit design.

T1s can have issues. I would say that its a gamble because of how good they are. can possibly be repaired by idk how, depends on what the issue is. replace the caps and such at least. Oxidized pot and that deoxit stuff didn’t do a thing. It is still however the same fundamental circuit as the T1 from 198X, including plate resistors that need to be replaced with a CCS mod.

Also don’t underestimate how much of an upgrade the front panel is on both relative to those hard edged blocks they used to use, before you go hunting for a T1s hoping to get a deal. They all upgrade extremely easy, all this old af stuff still old af the newer one just feels nicer — I’m also a fan of them keeping 6cg7s in that circuit for the last time before the most recent revision where they made it an ECC99 tube setup. because I am a little broke now and 6cg7 is pretty cheapo. Lots of these amps have just been gathering entropy in very humid Japan. The rounded corners are the unsung heroes of preventing entire corners snapping off the faceplate on the newer models. seriously look at classifieds its way more common than they should be.

in general though, I wouldn’t write off these amps modded. They sound like they were made in different universes with the mods. Be careful with the 006tS one aspect though, this model is when they started cutting transformer posts to prevent voltage switches, some can be rescued but they also started installing 100V only transformers, no other windings present. make sure you know what you’re getting.

 

[hewlett168]

The SRM-006tS, I’m quite positive, was made because many parts from the previous model were becoming obsolete or never made. A word of warning: Stax does not sell their modified dual concentric pot made by Alps as a spare part and neither does Alps, so I have a pretty much scrap T1s for a while. so for that reason I would try to lean toward a newer unit on that circuit design.

T1s can have issues. I would say that its a gamble because of how good they are. can possibly be repaired by idk how, depends on what the issue is. replace the caps and such at least. Oxidized pot and that deoxit stuff didn’t do a thing. It is still however the same fundamental circuit as the T1 from 198X, including plate resistors that need to be replaced with a CCS mod.

Also don’t underestimate how much of an upgrade the front panel is on both relative to those hard edged blocks they used to use, before you go hunting for a T1s hoping to get a deal. They all upgrade extremely easy, all this old af stuff still old af the newer one just feels nicer — I’m also a fan of them keeping 6cg7s in that circuit for the last time before the most recent revision where they made it an ECC99 tube setup. because I am a little broke now and 6cg7 is pretty cheapo. Lots of these amps have just been gathering entropy in very humid Japan. The rounded corners are the unsung heroes of preventing entire corners snapping off the faceplate on the newer models. seriously look at classifieds its way more common than they should be.

in general though, I wouldn’t write off these amps modded. They sound like they were made in different universes with the mods. Be careful with the 006tS one aspect though, this model is when they started cutting transformer posts to prevent voltage switches, some can be rescued but they also started installing 100V only transformers, no other windings present. make sure you know what you’re getting.

If I may add a question: Spritzer writes on his website that the "Stax SRM-700t uses the exact same circuit as the SRM-T1/006t/007t". My question to you is: if you apply the CCS mod and replace the output caps of the T1(S), 006t(I/II/ts) or 007t(I/II), would they sound mostly identical? Or is there something inherent to each model that makes it different/preferable.

 

[csl67]

If I may add a question: Spritzer writes on his website that the "Stax SRM-700t uses the exact same circuit as the SRM-T1/006t/007t". My question to you is: if you apply the CCS mod and replace the output caps of the T1(S), 006t(I/II/ts) or 007t(I/II), would they sound mostly identical? Or is there something inherent to each model that makes it different/preferable.

I have both a spritzer modded T1s (the scrap one), and 006tS with the extra mod of a custom proper transformer since it was a 100v unit, also from spritzer to replace the T1s. I can’t compare them for you even though we have the same headphones and I have two amps because the T1s sounds broken, since it is... I’m keeping it company until I ship it back out to him. I have no reason to believe there would be much different from amp to amp unless one is broken. And without harping on my experience much more again I feel it’s an important factor to think about simply because this circuit design has been used for such a long time. It’s older than me. So the biggest influence in variance I think would be age taking its toll. You can repair wear parts like capacitors but the pot is not buyable, and the newer pcbs are much better made, the old ones are pretty thin and were likely limited by manufacturing processes available, even visually they look peculiar. it’s possible a trace could’ve corroded/oxidized on mine. So given the choice I’d pick a newer revision. The possible exception to this would be the latest update to the T1 lineage which has switched to ECC99 tubes. In my opinion, I would trust 6CG7 NOS more because they were designed to be Serious Business stuff reliable and performant in uses both industrial and consumer in their day, but from a business standpoint I can see why they switched to something still made today. However, modern tube production is more of a cottage industry these days, and that’s why I’d stick to the 6CG7. That is just my personal opinion however. I also don’t think a mod board for this model has been created yet, plus I haven’t heard it.

I believe the 007t would sound different due to its tube configuration and other differences. It is a similar circuit design but the synergy of the components can’t be examined that way. It uses more tubes, different tubes, that operate differently and run at different points in their spec and the amp itself swings a higher voltage I believe. One thing birgir told me when I needed guidance and an amp for an 007 I impulse bought is that you can’t look at one spec in isolation and conclude it is ideal. For a bit I was under the impression that the one thing I needed to look for to drive my 007s was output current, but he helped me understand things more clearly. Unfortunately, I have heard the SRM-007t only in stock form and it is... one of the worst things I’ve ever heard when attempting to drive the 007A. To use with the 007A, it absolutely needs to be modded as do all of these tube amps from Stax. Without the energy that the mod restores, it just doesn’t really... work. The 007A’s closed stator is too insensitive and higher frequencies quite literally roll off without the power, since estats are operated on electrical principles at very demanding levels it’s more cut and dry than other audio products can be. Then the other issue, power required for lower and mid frequencies at louder levels/transient peaks/what some people just listen at. You could keep turning the knob all the way to the end and it wouldn’t get louder across the spectrum. I am sure with the mod it sounds like a champ. For a more experienced impression for sound differences I’d ask birgir since he’s likely had experience.

But modded, the 006tS is great. It’s clear, controlled, clear and resolving but has body so it doesn’t sound thin, in general it just sounds “like it should”. Exactly what I want from an estat amp. I understand the existing mythology behind the 007 sort of imparts anxiety that you may need an amp that costs as much as a car, but I don’t think it’s necessary right out of the gate. I don’t even feel the need to upgrade anytime soon (well, I’m terribly broke right now as well lol, but it is a temporary issue — covid pinged through my family during delta and it didn’t take our lives but a toll was paid). I am sure without a doubt the KG and descended amps are better, I know they are better because I can read the circuit schematics online, but I’m happy until I can afford one of the no expenses spared KG amps. One thing I’ve learned from my time in non-electrostatic headphones is that I wish I skipped the middle step and that’s what I’m doing here. I’d definitely be buying from birgir again as well, and if you just want an affordable amp you can use comfortably, I would recommend his refurbished Stax amp selection to you as well, don’t let the T1s issue I talk about scare you. Not only was it taken care of but I was stepped up to a newer model at no charge and no trouble to me as that was what was available, it was simply done. The mods are preinstalled, and in the case of the 006tS, there was an error during manufacturing that Stax missed and he fixed it while going over the board. He’s a true professional. I dunno what happened with the T1s but with the way things were made right, I don’t care, crap happens especially when it’s shipped internationally.

The 353X you have is a good amp, I have borrowed one from a user elsewhere, but it’s meant for Lambdas, I’d imagine for lambdas it’s an outright powerhouse. the design unfortunately wouldn’t be what I’d recommend as even an entry level 007 experience. It “works” but it just has no headroom, so louder peaks might suffer from the roll off and other nasties and at louder volumes it definitely does. The modded tube amps, even the first step T1/s 006t/tA/tS, do provide that functional entry level experience in my opinion.

I kinda covered some of the stuff I said in my original post but I’m sober right now so I hope it imparts more clarity and made more sense, lol.

 

[hewlett168]

I have both a spritzer modded T1s (the scrap one), and 006tS with the extra mod of a custom proper transformer since it was a 100v unit, also from spritzer to replace the T1s. I can’t compare them for you even though we have the same headphones and I have two amps because the T1s sounds broken, since it is... I’m keeping it company until I ship it back out to him. I have no reason to believe there would be much different from amp to amp unless one is broken. And without harping on my experience much more again I feel it’s an important factor to think about simply because this circuit design has been used for such a long time. It’s older than me. So the biggest influence in variance I think would be age taking its toll. You can repair wear parts like capacitors but the pot is not buyable, and the newer pcbs are much better made, the old ones are pretty thin and were likely limited by manufacturing processes available, even visually they look peculiar. it’s possible a trace could’ve corroded/oxidized on mine. So given the choice I’d pick a newer revision. The possible exception to this would be the latest update to the T1 lineage which has switched to ECC99 tubes. In my opinion, I would trust 6CG7 NOS more because they were designed to be Serious Business stuff reliable and performant in uses both industrial and consumer in their day, but from a business standpoint I can see why they switched to something still made today. However, modern tube production is more of a cottage industry these days, and that’s why I’d stick to the 6CG7. That is just my personal opinion however. I also don’t think a mod board for this model has been created yet, plus I haven’t heard it.

I believe the 007t would sound different due to its tube configuration and other differences. It is a similar circuit design but the synergy of the components can’t be examined that way. It uses more tubes, different tubes, that operate differently and run at different points in their spec and the amp itself swings a higher voltage I believe. One thing birgir told me when I needed guidance and an amp for an 007 I impulse bought is that you can’t look at one spec in isolation and conclude it is ideal. For a bit I was under the impression that the one thing I needed to look for to drive my 007s was output current, but he helped me understand things more clearly. Unfortunately, I have heard the SRM-007t only in stock form and it is... one of the worst things I’ve ever heard when attempting to drive the 007A. To use with the 007A, it absolutely needs to be modded as do all of these tube amps from Stax. Without the energy that the mod restores, it just doesn’t really... work. The 007A’s closed stator is too insensitive and higher frequencies quite literally roll off without the power, since estats are operated on electrical principles at very demanding levels it’s more cut and dry than other audio products can be. Then the other issue, power required for lower and mid frequencies at louder levels/transient peaks/what some people just listen at. You could keep turning the knob all the way to the end and it wouldn’t get louder across the spectrum. I am sure with the mod it sounds like a champ. For a more experienced impression for sound differences I’d ask birgir since he’s likely had experience.

But modded, the 006tS is great. It’s clear, controlled, clear and resolving but has body so it doesn’t sound thin, in general it just sounds “like it should”. Exactly what I want from an estat amp. I understand the existing mythology behind the 007 sort of imparts anxiety that you may need an amp that costs as much as a car, but I don’t think it’s necessary right out of the gate. I don’t even feel the need to upgrade anytime soon (well, I’m terribly broke right now as well lol, but it is a temporary issue — covid pinged through my family during delta and it didn’t take our lives but a toll was paid). I am sure without a doubt the KG and descended amps are better, I know they are better because I can read the circuit schematics online, but I’m happy until I can afford one of the no expenses spared KG amps. One thing I’ve learned from my time in non-electrostatic headphones is that I wish I skipped the middle step and that’s what I’m doing here. I’d definitely be buying from birgir again as well, and if you just want an affordable amp you can use comfortably, I would recommend his refurbished Stax amp selection to you as well, don’t let the T1s issue I talk about scare you. Not only was it taken care of but I was stepped up to a newer model at no charge and no trouble to me as that was what was available, it was simply done. The mods are preinstalled, and in the case of the 006tS, there was an error during manufacturing that Stax missed and he fixed it while going over the board. He’s a true professional. I dunno what happened with the T1s but with the way things were made right, I don’t care, crap happens especially when it’s shipped internationally.

The 353X you have is a good amp, I have borrowed one from a user elsewhere, but it’s meant for Lambdas, I’d imagine for lambdas it’s an outright powerhouse. the design unfortunately wouldn’t be what I’d recommend as even an entry level 007 experience. It “works” but it just has no headroom, so louder peaks might suffer from the roll off and other nasties and at louder volumes it definitely does. The modded tube amps, even the first step T1/s 006t/tA/tS, do provide that functional entry level experience in my opinion.

I kinda covered some of the stuff I said in my original post but I’m sober right now so I hope it imparts more clarity and made more sense, lol.

Thanks for the response! There is one very important thing to mention in my considerations: I listen at a very low volume level compared to many people here. Actually, when I use the 007Mk2 without EQ on the 353X I am only at 7-8 o'clock, so basically in the lowest 10 percent of listening volume. With EQ, I am at 9'oclock. That means I have some a KGSSHV would maybe not suit my needs very well (besides not being able to afford it), because I would literally only use a few percent of the volume dial and volume imbalance issues could be had so low on the dial. Also, at that listening volume, maybe a lack of power is not as relevant?

Besides, I still think that tubes have something special, especially with a SR-009 that I hope to have in the future. My consideration would be this: what would be the best tube energizer for around 1000 euro? In reality, that means I am restricted to either the T1S or 006t, because the 007t will be substantially more. If I read your answer correctly, it is better to be safe than sorry and get a later revision, so possibly 006ts? Because the difference between the differen 006t models is also non-existent?

 

[csl67]

Thanks for the response! There is one very important thing to mention in my considerations: I listen at a very low volume level compared to many people here. Actually, when I use the 007Mk2 without EQ on the 353X I am only at 7-8 o'clock, so basically in the lowest 10 percent of listening volume. With EQ, I am at 9'oclock. That means I have some a KGSSHV would maybe not suit my needs very well (besides not being able to afford it), because I would literally only use a few percent of the volume dial and volume imbalance issues could be had so low on the dial. Also, at that listening volume, maybe a lack of power is not as relevant?

Besides, I still think that tubes have something special, especially with a SR-009 that I hope to have in the future. My consideration would be this: what would be the best tube energizer for around 1000 euro? In reality, that means I am restricted to either the T1S or 006t, because the 007t will be substantially more. If I read your answer correctly, it is better to be safe than sorry and get a later revision, so possibly 006ts? Because the difference between the differen 006t models is also non-existent?

Well, it’s worth noting that the end-of-the-line enthusiast amps use high of high end TDK or RK50 volume pots, which both have a much larger range of logarithmic adjustments, and are very very well channel matched and free of noise. They are of course very expensive, also, contributing to the cost of entry.

I’m glad to hear your listen at less superhuman levels — some of the listening level anecdotes I see around here worry me. I’m young and I do more than most to preserve my hearing, often wearing earplugs and such when possible (I have great hearing range even for my age, but it can be a bit of a curse with sensory hypersensitivity from my autism).

Birgir currently has a 006tA and 006tS on his used and one off page, both are sort of in your budget range (just barely off), so might as well go with the latest... or latetS. I agree that latest is safest as long as your budget allows. The T1S up there would be cheaper, but why not? Plus, the rounded front plate on the new ones... it’s so nice. Those totally flat block ones do have a sort of minimal appeal until an errant move or object hits it and suddenly it’s missing a corner.

Tubes are nice, especially tubes that don’t break the bank. I’m gonna try some RCA flat tops in mine.

 

[hewlett168]

Well, it’s worth noting that the end-of-the-line enthusiast amps use high of high end TDK or RK50 volume pots, which both have a much larger range of logarithmic adjustments, and are very very well channel matched and free of noise. They are of course very expensive, also, contributing to the cost of entry.

I’m glad to hear your listen at less superhuman levels — some of the listening level anecdotes I see around here worry me. I’m young and I do more than most to preserve my hearing, often wearing earplugs and such when possible (I have great hearing range even for my age, but it can be a bit of a curse with sensory hypersensitivity from my autism).

Birgir currently has a 006tA and 006tS on his used and one off page, both are sort of in your budget range (just barely off), so might as well go with the latest... or latetS. I agree that latest is safest as long as your budget allows. The T1S up there would be cheaper, but why not? Plus, the rounded front plate on the new ones... it’s so nice. Those totally flat block ones do have a sort of minimal appeal until an errant move or object hits it and suddenly it’s missing a corner.

Tubes are nice, especially tubes that don’t break the bank. I’m gonna try some RCA flat tops in mine.

I think tubes are somewhat of a requirement. You lose magic by using solid state, even if you have to offer a bit of resolution. Honestly, looking at second-hand prices T1S and 006t seem to be priced very similarly, so might as well go for the later ones.

Preserving hearing is really a concern of mine, after all the horror stories around here. Music also does not sound better louder, in my opinion.

 

[kevin gilmore]

srm-t1 (all versions) srm-006 (all versions) srm-007 (all versions) are all the same schematic. The srm-007 uses 2 tubes per channel instead of one with dual triodes in parallel.
srm-500t and srm-700t are ever so slightly different (jfet tube drive), but all these amps are triode output tubes with resistor plate loads. And all have the same power supply voltages.

 

[hewlett168]

srm-t1 (all versions) srm-006 (all versions) srm-007 (all versions) are all the same schematic. The srm-007 uses 2 tubes per channel instead of one with dual triodes in parallel.
srm-500t and srm-700t are ever so slightly different (jfet tube drive), but all these amps are triode output tubes with resistor plate loads. And all have the same power supply voltages.

Great to see a response from Kevin Gilmore on this thread.

So the difference between each version is just a different use of components (more modern/robust, but not providing better performance?) based on the same schematic? Between the T1 and the 006t models, is there any specific version to look out for or is it basically most logical to get the most recent assuming equal price, because they are essentially the same?

 

[kevin gilmore]

different components. not newer or more robust. Probably what they were able to get. At least 10 different manufacturers of Plate Resistors. At least 6 different electrolytic capacitor manufacturers. All except the 700t use a couple of manufacturers of 6fq7/6cg7. The issue with the volume controls is unfortunate given the lack of replacement parts.
stax jacks were not available either until i started making them. Thats what happens when you build exactly the same thing for 45 years. Only one transformer manufacturer that i know of. And replacements of those are not available although they do seem to be quite reliable.

 

[hewlett168]

different components. not newer or more robust. Probably what they were able to get. At least 10 different manufacturers of Plate Resistors. At least 6 different electrolytic capacitor manufacturers. All except the 700t use a couple of manufacturers of 6fq7/6cg7. The issue with the volume controls is unfortunate given the lack of replacement parts.
stax jacks were not available either until i started making them. Thats what happens when you build exactly the same thing for 45 years. Only one transformer manufacturer that i know of. And replacements of those are not available although they do seem to be quite reliable.

If I may add something: how would the 006t compare to the 700t sonically and in terms of performance, because of the slightly different schematic, assuming the CCS mod is applied?

And the 006t to the 007t, because of the different tube setup? It really is very difficult to get a good grasp of the differences between each model, and if the price differences are justified.

 

[lupoal]

...enthusiast amps use high of high end TDK or RK50 volume pots

do you know where I could find info about this? I'm searching the web without success