[zolkis]

What's your opinion on the SRM-1 Mk2, when modern caps are installed? How does it stack up on the scale of stax amp awesomeness? And thriftiness lol.

I think that simple re-capping doesn't make it a better amp (design), max a better sounding same-class amp. I actually side-use an SRM-1 Mk2, recapped, some other parts changed and improved PSU. It's quite powerful, quite dynamic, but also more "rough" than the BHSE. It can definitely drive the 007 Mk1/2/3 and 009. The mods didn't change its basic sound character. At least it doesn't get harder sounding even at max volume. It does the home work pretty well, yet I don't put it on any awesomeness chart, it's probably similar class as the 353X, for me.

 

[AthenaZephyrian]

I think that simple re-capping doesn't make it a better amp (design), max a better sounding same-class amp. I actually side-use an SRM-1 Mk2, recapped, some other parts changed and improved PSU. It's quite powerful, quite dynamic, but also more "rough" than the BHSE. It can definitely drive the 007 Mk1/2/3 and 009. The mods didn't change its basic sound character. At least it doesn't get harder sounding even at max volume. It does the home work pretty well, yet I don't put it on any awesomeness chart, it's probably similar class as the 353X, for me.

That's fair. The old caps really congested the sound. I think I have one of the early units, and the previous owner used the thing a ton, so they were on their last leg, which probably explains the magnitude of the change. I did an extensive side-by-side of my HE400i and the L300 before hand, and while I can't A/B the old amp against it recapped, I can say that the gap between the setup and the HE400i grew a fair bit post-recap. Perhaps it didn't jump class, but it sounded much cleaner.

I got the SRM-1 Mk2 because I couldn't afford the better amps, didn't want the dull sound of the SRM-252S, and heard that the SRM-1 Mk2 compared well to the 353X. Not because I expected recapping to produce the best amp ever

What other parts did you change?

Yes, I wasn't expecting it to go on "best energizers list". I was joking that all stax energizers (except the 252...) are darn decent compared to typical $100-200 mid-fi units. Pardon me. I was really asking how it compared to typical lower-grade units. The comparison to 353X is a good answer. Thanks

 

[JimL11]

Don't know honestly, I have not looked into Stax amps very thoroughly. @JimL11 ought to have an excellent answer.

No experience with the SRM-1 MkII but besides @zolkis, I believe @Ali-Pacha has posted impressions of it.

 

[miko64]

Questions to the wizards:

What is actually the difference between srm 252 and 353? I thought I read that the have essentially the same circuit with different power supplies?
If yes - why is srm 252 (perceived) much worse?

Thx

M

 

[bearFNF]

Questions to the wizards:

What is actually the difference between srm 252 and 353? I thought I read that the have essentially the same circuit with different power supplies?
If yes - why is srm 252 (perceived) much worse?

Thx

M

Here you go:

●Frequency response:
252s is DC- 35 kHz (40Vr.m.s. output SR-207, when using one unit)
353x is DC - 90kHz (when used with one SR-L series Earspeaker)
●Rated input level:
252s is125 mV with 100V output
353x is 100mV (at 100V output)
●Maximum input level both are 30 V r.m.s. with volume at minimum setting
●Gain:
252s is 58dB
353x is Gain: 60dB
●Total harmonic distortion:
252s is 0.01% (1 kHz / during 100 V r.m.s. output)
353x is 0.01% or less (with one SR-L500 at 100Vr.m.s. / 1kHz output)
●Input impedance
252s is 50kΩ (RCA)
353x is 50kΩ(RCA) / 50k Ω x 2 (XLR)
●Maximum output voltage:
252s is 280 V r.m.s. / 1 kHz
353x is 400Vr.m.s. / 1kHz
●Standard bias voltage both are DC580V (PRO bias)
●Power consumption
252s is DC12V, 4W
353x is 30W
●Temperature range for use both are Between 0º and 35ºC, max. 90% (no condensation)
●External dimensions
252s is 132 (W) × 38 (H) × 132 (D) mm (without Knob, Pin jack)
353x is 150 (W) x100 (H) x360 (D) mm (protruding portion included)
●Weight
252s is 540g
353x is 3.0kg

 

[JimL11]

Questions to the wizards:

What is actually the difference between srm 252 and 353? I thought I read that the have essentially the same circuit with different power supplies?
If yes - why is srm 252 (perceived) much worse?

Thx

M

As BearFNF states, the primary differences between the two is the power supply and the amount of available power. The 252 uses a wall wart 12VDC power supply which is stepped up to HV in the amp, whereas the 353 has a linear HV supply. The step-up process results in an increased noise/hash level. Also, as indicated by the power consumption, the 252 has much less current in the output stage because its small size doesn't allow for the presence of large heat sinks. The 252 only runs about 2.4 mA output stage current per channel, whereas the 353 runs about 11mA per channel. This means that the 252 has much less reserve.

 

[AthenaZephyrian]

Anyone happen to know what the chances of a driver failure/tear are in the L300 headphones? I get neurotic about these things after having 2 HE400i driver failures....and I know these use a thin membrane.

I'd imagine that the fact that the distance between the tro stator grates is so small helps a lot; there's not as much room for the diazepam (autofill has a mind of its own, I meant diaphragm, but this is entertaining) to bend.

 

[cjeong]

Anyone happen to know what the chances of a driver failure/tear are in the L300 headphones? I get neurotic about these things after having 2 HE400i driver failures....and I know these use a thin membrane.

I'd imagine that the fact that the distance between the tro stator grates is so small helps a lot; there's not as much room for the diazepam (autofill has a mind of its own, I meant diaphragm, but this is entertaining) to bend.

My l300s been going strong for 6 months now. Idk about long term.

 

[AthenaZephyrian]

My l300s been going strong for 6 months now. Idk about long term.

Hopefully they are like the Lambdas. Enough of them survive to ebay age that they seem surprisingly sturdy.

 

[BoogieWoogie]

Is it wise this days to buy a SRM-1 MK2 for 400$ or there's better options out there for the money?

 

[JimL11]

Anyone happen to know what the chances of a driver failure/tear are in the L300 headphones? I get neurotic about these things after having 2 HE400i driver failures....and I know these use a thin membrane.

I'd imagine that the fact that the distance between the tro stator grates is so small helps a lot; there's not as much room for the diazepam (autofill has a mind of its own, I meant diaphragm, but this is entertaining) to bend.

Stax have traditionally been very durable. I have an SR-5 from the 1980's and Lamda Nova Signature from the 1990's that are still going strong. HFM on the other hand is not known for long term reliability.

Is it wise this days to buy a SRM-1 MK2 for 400$ or there's better options out there for the money?

SRM-1 Mk2's date from the 1980s, so they all need their electrolytic caps replaced. One issue with all the old amps is that it is likely that if any of the transistors go bad they are probably obsolete. OTOH, that said, they seem to be quite realiable as many are still in use. I like the SRM-T1 series myself but then I'm a bit of a tube guy, and the older models also need electrolytic cap replacement, however modifying them by replacing the plate output resistors with constant current loads makes them capable of driving even the SR-007s for a bargain price.

 

[AthenaZephyrian]

Stax have traditionally been very durable. I have an SR-5 from the 1980's and Lamda Nova Signature from the 1990's that are still going strong. HFM on the other hand is not known for long term reliability.

Awesome. Is it normal to occasionally get a bit of a clicking noise when pressure is applied to the driver housing or the headphones are put on? It sounds like the diaphragm pushing up against the charges grate or something. Just wanted to make sure I don't need to be worried.

SRM-1 Mk2's date from the 1980s, so they all need their electrolytic caps replaced. One issue with all the old amps is that it is likely that if any of the transistors go bad they are probably obsolete. OTOH, that said, they seem to be quite realiable as many are still in use. I like the SRM-T1 series myself but the older models also need electrolytic cap replacement, and modifying them by replacing the plate output resistors with constant current loads makes them capable of driving even the SR-007s for a bargain price.

Hmm. Well, if that happens, I guess I'm replacing them...even if it means somehow adapting modern tech...because I can't afford to pitch it and get a new one. Hope you're right about their durability/life expectancy.

 

[spacequeen7]

I recently acquired SR L-300 LE and couldn't be more disappointed,it seams the headband is too short ,I'm not getting proper seal around my ears since the headband is stretched to the limit
Was wondering if all lambda headbands are the same size ,any way to fix this ?

 

[DJ The Rocket]

its small size doesn't allow for the presence of large heat sinks

Stax heat sinks are serious business. The big ones in my 727 actually get hot to the touch -- not just warm -- after the universal feedback mod anyway. I've thought about cutting a hole in the top of the case to install a powered cooling fan!

 

[DJ The Rocket]

I recently acquired SR L-300 LE and couldn't be more disappointed,it seams the headband is too short ,I'm not getting proper seal around my ears since the headband is stretched to the limit
Was wondering if all lambda headbands are the same size ,any way to fix this ?

This sounds like what happened with my SR-407. They had to be stretched so tight over my head I would get headaches.

I don't know how I fixed it. I pulled both driver cups off of the headband assembly to inspect them, and then I put them back on in exactly the same way they came off (at least as far as I can tell; they match the "before" pictures I snapped before taking them apart). But somehow, after I put them back together, they fit normally.

Is this your first pair of Lambdas?