[573531]

Maybe you should be in basement-fi rather than summit-fi

Is there where your man cave is at? Now I understand how amps with more heat dissipation would rank better. My bad.

 

[DougD]

On the topic, I can finally share some data from testing my Lundahl LL1630 setup and limited testing with all the gear I have available... It's fascinating to see it all plotted out and compare STAX gear to transformer setup. The STAX SRM-1 surprised me with its low end performance but also how quickly it falls off, also interesting was its behaviour changing quite dramatically based on the load used. Even a 2 wire reading from my oscilloscope (1mOhm) would drag down its output significantly...

<< snip snip >>

What was used:

STAX SRM-1 mk2 (Fully restored and calibrated)
STAX SRD-7 modified with 4.7ohm resistors and switching removed (performed the best compared to my other SRDs)
Lundahl LL1630 - Driven by Topping LA90 Monoblocks (Roughly 90Wpc)
Lundahl LL1630 - Driven by Sony TA-N9000ES (Roughly 200Wpc)
Lundahl LL1630 - Driven by Luxman LV103 Tube / MOSFET Hybrid (Roughly 75Wpc)
Lundahl LL1630 - Driven by Encel CSM-40 OT Tube (Roughly 18Wpc)

I know less about electronics than fish know about bicycles, but this really shows some very different stuff. INTERESTING!

You said the STAX SRM-1 mk2 is "fully restored and calibrated" ... so no CC mod (?constant current) ?

Same amp I'm using to drive pre-Lxxx lambdas. Mine is probably not well-calibrated. My hearing cuts off at 14.5k so I don't detect much of the high freq dropoff. Guess I know why the Stax almost never sound too bright and edgy to me.

Did I mention Very Interesting? Thanks for sharing.

 

[aokman]

I know less about electronics than fish know about bicycles, but this really shows some very different stuff. INTERESTING!

You said the STAX SRM-1 mk2 is "fully restored and calibrated" ... so no CC mod (?constant current) ?

Same amp I'm using to drive pre-Lxxx lambdas. Mine is probably not well-calibrated. My hearing cuts off at 14.5k so I don't detect much of the high freq dropoff. Guess I know why the Stax almost never sound too bright and edgy to me.

Did I mention Very Interesting? Thanks for sharing.

Not aware of any mods for the SRM-1mk2 only the SRM-T1? The restoration included new trimpots, diodes and all new capacitors except the polystyrenes. Outputs were removed and reseated with new thermal paste.

I was going to experiment with further improvements on it but abandoned it once I found out about the Lundahl Transformers and put all my efforts into that and a modern pro bias setup.

 

[oneguy]

Is there where your man cave is at? Now I understand how amps with more heat dissipation would rank better. My bad.

Whoa whoa whoa, let’s not put down basement man caves. I’ve seen some good ones and I’ll be rocking one eventually. Any dedicated space that can be carved out is a win

 

[HifiXMen]

On the topic, I can finally share some data from testing my Lundahl LL1630 setup and limited testing with all the gear I have available... It's fascinating to see it all plotted out and compare STAX gear to transformer setup. The STAX SRM-1 surprised me with its low end performance but also how quickly it falls off, also interesting was its behaviour changing quite dramatically based on the load used. Even a 2 wire reading from my oscilloscope (1mOhm) would drag down its output significantly...

In contrast the Lundahl LL1630 just doesn't give a crap really, it will deliver consistent results regardless of what load I put on it and is basically flawless across the FR (voltage output), its only limitation seems to be its fall off at 20hz and lower (270Vrms limit when the core saturates) it may be possible to work around this with a different winding configuration or possibly series them???

Out of the amplifiers used, the Topping LA90 was the most linear, clean and consistent from what I saw and 2 of them fit nicely on a desk with balanced inputs used. Also threw in some random testing with different amplifiers to see how it impacts the response and also a 1960s Encel tube amplifier for the LOLs of "tube sound"

Tried various loads from 120pF capacitor to 150kOhm resistor with capacitor in series / parallel and ended up settling on the 120pF capacitor alone with a single wire reading off my scope and multimeter (10mOhm) to give the SRM-1 a fair chance. I chose 150Vrms as the reference based on my listening levels.

What was used:

STAX SRM-1 mk2 (Fully restored and calibrated)
STAX SRD-7 modified with 4.7ohm resistors and switching removed (performed the best compared to my other SRDs)
Lundahl LL1630 - Driven by Topping LA90 Monoblocks (Roughly 90Wpc)
Lundahl LL1630 - Driven by Sony TA-N9000ES (Roughly 200Wpc)
Lundahl LL1630 - Driven by Luxman LV103 Tube / MOSFET Hybrid (Roughly 75Wpc)
Lundahl LL1630 - Driven by Encel CSM-40 OT Tube (Roughly 18Wpc)

it's simply awesome, thank you for sharing such valuable data

 

[kael13]

Hey all. So I tried some STAX Lambdas 4-5 years ago at a hi-fi shop, I think it was either the L500s and L700s or the L300s and L500s, can't remember which but I and my dad were definitely wow'd and talking about them excitedly the entire drive home. They seemed to knock it out the park with any genre.
Cut to a couple weeks ago when I'd mostly forgotten about electrostats and had an itch to research the Sennheiser HD800S as a potential buy. Then suddenly I realised that a specialised headphone that sounds bad with rock and electronic music is not something I want.

So now I'm thinking that in the end it always comes back to STAX. I want to go for some L700 Mk2s, but the fact remains I still need an energiser. I'm looking at a used D50 right now that could be a purchase. Honestly, I want to avoid tubes but the Woo WA7e might've swung me if it was more easily available in the UK. Another possibilty is an SRM-400S, but my DAC, a Burson Audio Composer 3XP, is currently hooked up to my desktop speakers. I'm guessing I'd have to fiddle with cables every time I want to switch between.
Is it okay to buy used for energisers? Any other possibilities?

Budget is a bit tight because I'm moving and have spent a fair bit on other things recently.

 

[ColSaulTigh]

Hey all. So I tried some STAX Lambdas 4-5 years ago at a hi-fi shop, I think it was either the L500s and L700s or the L300s and L500s, can't remember which but I and my dad were definitely wow'd and talking about them excitedly the entire drive home. They seemed to knock it out the park with any genre.
Cut to a couple weeks ago when I'd mostly forgotten about electrostats and had an itch to research the Sennheiser HD800S as a potential buy. Then suddenly I realised that a specialised headphone that sounds bad with rock and electronic music is not something I want.

So now I'm thinking that in the end it always comes back to STAX. I want to go for some L700 Mk2s, but the fact remains I still need an energiser. I'm looking at a used D50 right now that could be a purchase. Honestly, I want to avoid tubes but the Woo WA7e might've swung me if it was more easily available in the UK. Another possibilty is an SRM-400S, but my DAC, a Burson Audio Composer 3XP, is currently hooked up to my desktop speakers. I'm guessing I'd have to fiddle with cables every time I want to switch between.
Is it okay to buy used for energisers? Any other possibilities?

Budget is a bit tight because I'm moving and have spent a fair bit on other things recently.

How about this thing from Topping: https://apos.audio/products/topping-eha5-electrostatic-amplifier?_pos=1&_sid=63876f77b&_ss=r

 

[mulveling]

On the topic, I can finally share some data from testing my Lundahl LL1630 setup and limited testing with all the gear I have available... It's fascinating to see it all plotted out and compare STAX gear to transformer setup. The STAX SRM-1 surprised me with its low end performance but also how quickly it falls off, also interesting was its behaviour changing quite dramatically based on the load used. Even a 2 wire reading from my oscilloscope (1mOhm) would drag down its output significantly...

In contrast the Lundahl LL1630 just doesn't give a crap really, it will deliver consistent results regardless of what load I put on it and is basically flawless across the FR (voltage output), its only limitation seems to be its fall off at 20hz and lower (270Vrms limit when the core saturates) it may be possible to work around this with a different winding configuration or possibly series them???

Out of the amplifiers used, the Topping LA90 was the most linear, clean and consistent from what I saw and 2 of them fit nicely on a desk with balanced inputs used. Also threw in some random testing with different amplifiers to see how it impacts the response and also a 1960s Encel tube amplifier for the LOLs of "tube sound"

Tried various loads from 120pF capacitor to 150kOhm resistor with capacitor in series / parallel and ended up settling on the 120pF capacitor alone with a single wire reading off my scope and multimeter (10mOhm) to give the SRM-1 a fair chance. I chose 150Vrms as the reference based on my listening levels.

What was used:

STAX SRM-1 mk2 (Fully restored and calibrated)
STAX SRD-7 modified with 4.7ohm resistors and switching removed (performed the best compared to my other SRDs)
Lundahl LL1630 - Driven by Topping LA90 Monoblocks (Roughly 90Wpc)
Lundahl LL1630 - Driven by Sony TA-N9000ES (Roughly 200Wpc)
Lundahl LL1630 - Driven by Luxman LV103 Tube / MOSFET Hybrid (Roughly 75Wpc)
Lundahl LL1630 - Driven by Encel CSM-40 OT Tube (Roughly 18Wpc)

Yes, very interesting data, thank you @aokman !
Not that I know circuits, but this definitely gels with what the Stax Mafia has discussed before -- with many of the direct drive electrostatic amps, higher output device bias extends the high frequency response (not low frequency). Of course this comes at the expense of great heat dissipation, etc. I remember when KGSShv Carbon was new, many builders purposely backed off the bias from 20mA to say 16 or 17mA, specifically to improve its sonic match to 009.

The transformers struggle on the opposite side of the spectrum, in bass. Not that what you show is of concern -- they seem to acquit themselves very well. But I think its performance might be very dependent on the actual reactive load presented by the headphones?

The SRM-1 is very low powered compared to the "Mafia" amps like KGSShv / etc, and I think that reflects in its poor high frequency performance at higher volume levels. As a loud listener I have heard the Stax amps (727) fall apart as you push volume. They're not stellar at lower volume either but they really struggle as you push it. This is a different world from dynamics headphones & amps -- where you can very easily have such ludicrous amount of headroom that power will never be a concern. I have experienced at least some correlation between the power consumption of direct-drive electrostatic amps and the subjective sound quality, which is why I found Dr. Kevin Gilmore's listing interesting.

 

[aokman]

Yes, very interesting data, thank you @aokman !
Not that I know circuits, but this definitely gels with what the Stax Mafia has discussed before -- with many of the direct drive electrostatic amps, higher output device bias extends the high frequency response (not low frequency). Of course this comes at the expense of great heat dissipation, etc. I remember when KGSShv Carbon was new, many builders purposely backed off the bias from 20mA to say 16 or 17mA, specifically to improve its sonic match to 009.

The transformers struggle on the opposite side of the spectrum, in bass. Not that what you show is of concern -- they seem to acquit themselves very well. But I think its performance might be very dependent on the actual reactive load presented by the headphones?

The SRM-1 is very low powered compared to the "Mafia" amps like KGSShv / etc, and I think that reflects in its poor high frequency performance at higher volume levels. As a loud listener I have heard the Stax amps (727) fall apart as you push volume. They're not stellar at lower volume either but they really struggle as you push it. This is a different world from dynamics headphones & amps -- where you can very easily have such ludicrous amount of headroom that power will never be a concern. I have experienced at least some correlation between the power consumption of direct-drive electrostatic amps and the subjective sound quality, which is why I found Dr. Kevin Gilmore's listing interesting.

Yes it seems quite tricky to find an accurate load and need to try and read between the lines by trying different things and seeing how it changes the output. I cannot say I saw any real difference between different capacitor types, adding resistors / capacitors as a load etc. I have that data also if it’s of any use to anyone, I can share also, but only the SRM-1 really changes a lot… I may be missing something in regards to that? Wish I had more direct drive examples to explore. To me so far, the greatest benefit of a good transformer setup seems to be consistent, stable performance, regardless of what estats you throw at them…

270Vrms fall off isn’t a big issue with the Lundahl in reality from what I saw as the sinewave distortion isn’t massive and cleans up by 30hz / already very loud… but going to all the trouble of building it, would be great to see if there’s anything available from Lundahl that can shore up the bass region further with a larger core or something. There was an unrelated post on another forum about taking 2 output transformer secondaries and doing a series setup to double the voltage swing but I'm not experienced in this stuff.

Aside from that, the Lundal LL1630 almost feels like witchcraft with how well it’s tuned it is and so grateful for the community sharing this suggestion a long time ago so I thought id try and add more data to it…

Last piece for me to investigate before going back to the pro bias design is testing channel crosstalk and how much the transformers pickup from each other at listening levels and if shielding / more distance is required in the final iteration.

Planning to order the Dan Clark Corina soon so excited to keep the project moving…

 

[kevin gilmore]

You said the STAX SRM-1 mk2 is "fully restored and calibrated" ... so no CC mod (?constant current) ?

.

almost all of the stax made solid state amps already have constant current sources in the output stage.
for sure srmxh,srm252,smr313,srm323,srm353,srm717,srm727,srm500s,srm700s,srm-t8000
and probably a few others i forgot.

 

[ufospls2]

almost all of the stax made solid state amps already have constant current sources in the output stage.
for sure srmxh,srm252,smr313,srm323,srm353,srm717,srm727,srm500s,srm700s,srm-t8000
and probably a few others i forgot.

Hi @kevin gilmore , was wondering if you could take a quick look at this and share any thoughts. Not so much concerning audio quality, but safety for the headphones being used. As the product has relation to the iESL, and this was birgirs comments about the iESL

"Now for the really bad news, see the first picture, the string of resistors in front of the 5 pin connectors? Those pretty much have to be the ballast resistors run in series to increase the voltage handling. They are also high value resistors but I can't quite make out the value of them. Now follow the trace on left and see the cap that is there? Yup it is 10nf/1kV so it sure looks like the ****tards put a cap after the ballast resistor. Never, ever do that if you like the coating on the diaphragms..."

In another post he mentioned it wouldn't be a quick problem, but a problem over time for the coating on the diaphragms.

Basically don't want to plug in my headphones and damage the coating on the diaphragms etc..

https://ifi-audio.com/products/ican-phantom/

I'm not sure if you will be able to see the relevant area as the board appears to be stacked. Regardless, thanks for taking a look if you get a chance.

 

[kael13]

How about this thing from Topping: https://apos.audio/products/topping-eha5-electrostatic-amplifier?_pos=1&_sid=63876f77b&_ss=r

Mmm, the price is great but I have a Topping PA5 that failed completely in one channel after 6-8 months and had to go back. From a quick ASR survey, something like 30% of buyers experienced the same. I’m a little wary.

 

[ColSaulTigh]

Mmm, the price is great but I have a Topping PA5 that failed completely in one channel after 6-8 months and had to go back. From a quick ASR survey, something like 30% of buyers experienced the same. I’m a little wary.

I hear you - and I'm not advocating it other than it's inexpensive.

I'm a big believer of "buy once, cry once", so I'd go for one of the Carbons or KGGG or other custom built amps out there. I had a Stax SRM-007t and was very underwhelmed. Go big or.go home!

 

[cayfounnosett1982]

goo for one of the Carbons or KGGG or other custom built amps out there

right choice, totally agree

 

[Chefguru]

It’s an easy choice when a kgsshv and KGST can be had 2nd hand for 2k~ or new at 3k.
Both seriously good amplifiers that can run everything on the market.