[JimL11]

Interesting
Which amp is better Srm-1 or Srm-313 (for me them looks the same)?

I have no subjective impressions, as I have never heard either amp. However, the SRM-313 is a newer amp with a better circuit, in particular the output stage, which uses a constant current load, whereas the SRM-1 uses output resistors. This means the SRM-313 should have significantly better output current capability than the SRM-1.

 

[legopart]

Found only this information on the web

SRM-313

Type: All-stage semiconductors, Low-noise dual FET input Class A operation, Pure balance DC amplifier
Frequency characteristics: DC to 48,000 Hz with SR-303 only
Input impedance: 50KΩ
Amplification factor: 60dB
Maximum Output Voltage: 350V R.M.S. (1kHz)
Distortion factor: Max. 0.01% (with 1kHz, 100V r.m.s. output)
Input Terminals: 1 RCA
Input level: 100mV (with 100V output)
Bias voltage PRO 580V x 1, Normal 230V x 1
Electric power consumption: 29W
Ambient Temperature & Humidity: 0 to 35ºC / 90% max. without condensation
External Dimensions: 150 (W) x 101 (H) x 370 (D) cm
Weight: 2.9kg​

SRM-1

Inputs
There is one loop-through line-level input.
Rated 100 mV, 50KΩ
Loop-through means they are wired together; you can insert this in between any two other components, and even if it's turned-off, the signal goes through.
Gain
60 dB (1,000x).
In other words, a 100 mV input can produce a 100 V output at maximum gain.
Frequency Response
Rated DC - 20 kHz, ±1 dB, at 30 V with one pair of SR-Lambda.
Distortion
Rated 0.01% THD at 1 kHz.
Rated 0.05% THD at 100 V at 1 kHz while driving an SR-Lambda.
from the data:
Maximum Output Voltage: 350V R.M.S. (1kHz)
Electric power consumption: 33W
External Dimensions: 150 (W) x 87 (H) x 370 (D) mm
Weight: 2kg


They technically looks the same (without the fact that they created for Sr404 or Lambda Pro)​

 

[legopart]

The two units have different sound. The srm1 was a bit laid back. It paired better with sr-404s.
The sr202 was better with the srm-313. I sold both of them and my 404s.
The 202s remain here. I use them with the srd-7 and a vintage Sansui au717
The dynamics with a transformer box are very good. I also have akg q701s paired with a asl mghead
I use my speaker set up now quite a bit. So headphones aren't main go to anymore.

I am a Beyerdynamic fan, so cant understand about AKG, only to Beyerdynamic T1.

Unfortunate I have the srd-7 but as Self Biased that having a lots of delays between songs, so I dont like it!
I do not want to spend more money on amps, at this point I can't offer more then:
Aune x1s DAC
Aune x7s XLR amp
Stax Srm-1 as electrostatic amp

Stax Srm-1 best only with Stax Lambda Pro, but not with Sigma normal.
*Stax Sr-30 best for all amps

I think to mod the bias inside the Srd-7/SB to Normal biased version.
*also having the Srd-4, that can use only with Sr-30, and Beyerdynamic N1000 that can give only 180v bias.

In addition some one suggest me to order St-202 for not high price.

Still can find any information about the difference between Sr202/303/404, Sr207/307/407/507 and L300/500/700. And are they worth and compare with Stax Lambda Pro? (I also tried the Lambda Normal that broken, that I not liked!)

 

[ktm]

Keep in mind a srm1 mkII is an older unit and may need to be re-capped.
I did my unit just after getting it. The srm313 came with a sr202. It was a demo system.
I don't consider either to be better, just a bit different in sound.

As far as the srd7 goes, someone here mods and sells them moded for pro bias.
I believe he uses non self bias models. This might be a reasonable way to go
Without spending $$$. This of course assumes you already have a good
Stereo amp available.

The sr202 is a good value for the money. It doesn't have the highs and lows of the
Sr404 but it also doesn't have issues with treble harshness either.

 

[legopart]

Keep in mind a srm1 mkII is an older unit and may need to be re-capped.
I did my unit just after getting it. The srm313 came with a sr202. It was a demo system.
I don't consider either to be better, just a bit different in sound.

As far as the srd7 goes, someone here mods and sells them moded for pro bias.
I believe he uses non self bias models. This might be a reasonable way to go
Without spending $$$. This of course assumes you already have a good
Stereo amp available.

The sr202 is a good value for the money. It doesn't have the highs and lows of the
Sr404 but it also doesn't have issues with treble harshness either.

Lots of thanks! for all the help!
For now I have not enough free time for my hobbies, so maybe I will lost the chance to get The sr-202
My srm-1 looks almost new with the original case, when I have time I will check or even replace the caps

In addition I have some good speaker amp the Sony STR-DN1080, I plan to mod the srd-7/SB and even the srd-4 for my planned projects to make DIY electrostatic headphones and speaker, also mod the srd-7 to Biased one (or even Pro one).
here the schematics

The 7/sb, that I have looks like

 

[Kitchener]

Anyone have any experience running the SRD-7 (or similar) with a low power amps like the Bottlehead SEX?

The SRD-7 manual states 10 Watts minimum but at least one forumite I can recall from over on Bottlehead states he's pleased with the results but I would like a little more in depth feedback than "quite pleased".

I'm currently building a Millett Jonokuchi (2,5 Watts max output per channel) and wondering if there's any point in trying to Stax it up a bit down the line?

 

[legopart]

Do old vintage headphones need re-coating for sound better ? do someone tried to restore old headphones with re-coating the membrane ?

 

[VRacer-111]

Anyone have any experience running the SRD-7 (or similar) with a low power amps like the Bottlehead SEX?

The SRD-7 manual states 10 Watts minimum but at least one forumite I can recall from over on Bottlehead states he's pleased with the results but I would like a little more in depth feedback than "quite pleased".

I'm currently building a Millett Jonokuchi (2,5 Watts max output per channel) and wondering if there's any point in trying to Stax it up a bit down the line?

No experience, but a S.E.X. with C4S upgrade is something I've been wanting to do for a while and hopefully can soon, it's the only tube amp I'm interested in. I am curious as well how good it would be with the SRD-7. My L300 Limited setup uses a Mjolnir Audio modded SRD-7 powered from a NAD C275BEE stereo amp, which sounds noticeable better than a STAX SRM-323S driver unit. Subbass is noticeably beyond an Argon Mk3 with an even more full sounding body to it and great punch. I'll let you know how a S.E.X. with C4S compares whenever I get one and build it.

 

[gefski]

Anyone have any experience running the SRD-7 (or similar) with a low power amps like the Bottlehead SEX?

The SRD-7 manual states 10 Watts minimum but at least one forumite I can recall from over on Bottlehead states he's pleased with the results but I would like a little more in depth feedback than "quite pleased".

I'm currently building a Millett Jonokuchi (2,5 Watts max output per channel) and wondering if there's any point in trying to Stax it up a bit down the line?

Several years ago I had a Decware Zen Triode amp (2 wpc) and used it for a while to drive Stax SRD4/SR40, and similar Signet TK33 electrets. Sonically it was beautiful, but one time I was playing a Steve Swallow album, and his electric bass clipped in several places through the album. I knew it sounded like clipping. I hooked the electrets up to an NAD integrated and (1) there was no clipping anywhere; (2) it sure didn't sound as good overall as the Decware. So I concluded that I would need a second Decware amp and run them in mono if I wanted to continue with the electrets. I abandoned that and went with Lambdas and Stax amps.

No sweeping conclusions, just one experience.

 

[JimL11]

Anyone have any experience running the SRD-7 (or similar) with a low power amps like the Bottlehead SEX?

The SRD-7 manual states 10 Watts minimum but at least one forumite I can recall from over on Bottlehead states he's pleased with the results but I would like a little more in depth feedback than "quite pleased".

I'm currently building a Millett Jonokuchi (2,5 Watts max output per channel) and wondering if there's any point in trying to Stax it up a bit down the line?

No experience, but a S.E.X. with C4S upgrade is something I've been wanting to do for a while and hopefully can soon, it's the only tube amp I'm interested in. I am curious as well how good it would be with the SRD-7. My L300 Limited setup uses a Mjolnir Audio modded SRD-7 powered from a NAD C275BEE stereo amp, which sounds noticeable better than a STAX SRM-323S driver unit. Subbass is noticeably beyond an Argon Mk3 with an even more full sounding body to it and great punch. I'll let you know how a S.E.X. with C4S compares whenever I get one and build it.

Several years ago I had a Decware Zen Triode amp (2 wpc) and used it for a while to drive Stax SRD4/SR40, and similar Signet TK33 electrets. Sonically it was beautiful, but one time I was playing a Steve Swallow album, and his electric bass clipped in several places through the album. I knew it sounded like clipping. I hooked the electrets up to an NAD integrated and (1) there was no clipping anywhere; (2) it sure didn't sound as good overall as the Decware. So I concluded that I would need a second Decware amp and run them in mono if I wanted to continue with the electrets. I abandoned that and went with Lambdas and Stax amps.

No sweeping conclusions, just one experience.

The issue with the S.E.X or Declare is the low voltage output. The SRD-7 has a 25:1 transformer step-up, which means that 1 volt in results in 25 volts out. The Bottlehead is spec at 2 watts output, with a 16 ohm transformer output that means about 5.6 V RMS. The Decware is specified at 2.3 watts output into 8 ohms, which corresponds to a bit more than 4 V RMS. This puts their max output through the SRD-7 at about 100-140V RMS.

Note that the smallest Stax amp, the SRM-252 is specified at 280 VRMS. To match that, you need an amplifier that puts out at least 16 watts into 8 ohms into the SRD-7. The bigger Stax amps are specified at around 340-350 VRMS, which corresponds to around 25 watts into 8 ohms. The original Stax SRM-T2, which has the most voltage output of any Stax amp built, is specified at 635 VRMS which corresponds to about 80 watts into 8 ohms going into an SRD-7.

What all this means is that you don't need a Phase Linear 700 (350 watts/channel) going into an SRD-7, but something bigger than a S.E.X. would be more appropriate, unless you are limiting your listening to solo voice, chamber music, or soft rock at moderate levels.

 

[Kitchener]

The issue with the S.E.X or Declare is the low voltage output. The SRD-7 has a 25:1 transformer step-up, which means that 1 volt in results in 25 volts out. The Bottlehead is spec at 2 watts output, with a 16 ohm transformer output that means about 5.6 V RMS. The Decware is specified at 2.3 watts output into 8 ohms, which corresponds to a bit more than 4 V RMS. This puts their max output through the SRD-7 at about 100-140V RMS.

Note that the smallest Stax amp, the SRM-252 is specified at 280 VRMS. To match that, you need an amplifier that puts out at least 16 watts into 8 ohms into the SRD-7. The bigger Stax amps are specified at around 340-350 VRMS, which corresponds to around 25 watts into 8 ohms. The original Stax SRM-T2, which has the most voltage output of any Stax amp built, is specified at 635 VRMS which corresponds to about 80 watts into 8 ohms going into an SRD-7.

What all this means is that you don't need a Phase Linear 700 (350 watts/channel) going into an SRD-7, but something bigger than a S.E.X. would be more appropriate, unless you are limiting your listening to solo voice, chamber music, or soft rock at moderate levels.

That was a very good and informative (and perhaps a bit discouraging ) reply, thank you!

 

[VRacer-111]

That was a very good and informative (and perhaps a bit discouraging ) reply, thank you!

I'm still eventually getting the S.E.X. 3.0 with C4S (because it's for my dynamic and planar rigs), but from Jim's input it definitely looks like it just won't be enough for running the STAX system. I'm more than beyond pleased with the warm NAD C275BEE stereo amp (150W constant to 250W dynamic @ 8 ohm) was just curious on what a clean tube amp would sound like with it.

 

[JimL11]

I'm still eventually getting the S.E.X. 3.0 with C4S (because it's for my dynamic and planar rigs), but from Jim's input it definitely looks like it just won't be enough for running the STAX system. I'm more than beyond pleased with the warm NAD C275BEE stereo amp (150W constant to 250W dynamic @ 8 ohm) was just curious on what a clean tube amp would sound like with it.

Well, note that 100 volts RMS will produce 100 dB from most Stax headphones, which is really quite loud. But, if that is not enough, there are plenty of tube amps around that will put out 25-80 watts into 8 ohms, which is more than enough. Remember that with transformer outputs, you can increase the voltage by using the 16 ohm tap. Heck, an old Dynaco SCA-35 will put out 15 watts per channel into 16 ohms, which should be plenty of voltage for most people.

 

[feilonghuynh]

My new Stax L300 modded earpads with Hifiman headband (images show Modded and original heanldband).
My collection includes HE500, HE400i, LCD 2 fazor (recently sold), Focal Elex.

So far, the Stax sounds a league above my other headphones. Fast, clear, airy, and energetic instruments with potent, layered bass.

 

[feilonghuynh]