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Stax Sigma Low Bais and Stax Sigma Pros - Page 27

post #391 of 472
The same we use to heat our houses with which is sourced from some of the many geo-thermal powerplants outside of the city. This particular beach is situated a few hudred meters downhill from this structure which is actually a dressed up storage unit for hot water.
post #392 of 472
Thread Starter 
Hey everyone, I just wanted to let you know that I picked up another Stax Sigma Pro from Audiogon. It is sweet. I am thinking of bringing it to CanJam 2009. This will require me to use it on my flight from NYC on JetBlue Airlines to Long Beach, California and back again. It will be cool to see how people on the plane react to wearing these crazy but good sounding headphones on my flights. I am going to bring a camera to prove it. Scottsmrnyc
post #393 of 472

Need Info/Help w/SRM-T1; Sigma/404 v. Lambda Nova Sig comp

Well, glad you're happy, Scott! See, I sold them to him the other day. Great guy.

Need some info, folks. Please give me some direction or answers if you have them.

SRM-T1:
1. Got one in a deal 3/2008. Love it. Is it sonically or design-wise different from the T1S, other than the balance input and the multi input RCA's?
2. In search of the 'Holy Grail,' I realize that a Blue Hawaii or the new SE version is WAY out of my $ range. So, what mods have been developed to tweak this amp? Any outboard transformer couple P/S?

Sigma/404 v. Lambda Nova Sig comparison:
A pr. of Lambda Nova Sigs came w/the SRM-T1 deal. I like the LNS's but find them to be 'tonally balanced' too far to the high end making the highs painfully strident/edgy. This isn't a matter of all high no bass. I hear the full range reproduced.

On the other hand, I bought a pr. of minty Sig Pros and they sounded dull/dark/lacking a proper amount of shine in the highs (full overtone series).

So, I had YAMA's do the conversion with a pr. of 404's I found (side note: the flat brown cables on both the LNS's and the 404's was the same width--did I get snookered on the 404's or did I get a re-cabled LNS?). Now that improved the Sig Pros--plenty of bass and low-mid (don't see a need for thicker pads for a better seal), but the mids sound like they’re in a hole and the highs are better but still lack a little shine/sparkle from missing the full overtone series. YAMA's had asked if I wanted to have the interior hard foam replaced as stock or trimmed down.

Any ideas on how to further tweak the modded Sig Pros? Any thoughts on this 'trimmed inner foam' thing?

Thanks for any thoughts. Oh, and the 'Bonemaster' thing is because I play trombone--big band and classical (so I'm looking for the sound I hear live, playing in the group.
post #394 of 472
Quote:
Originally Posted by bonemaster77 View Post
SRM-T1:
1. Got one in a deal 3/2008. Love it. Is it sonically or design-wise different from the T1S, other than the balance input and the multi input RCA's?
2. In search of the 'Holy Grail,' I realize that a Blue Hawaii or the new SE version is WAY out of my $ range. So, what mods have been developed to tweak this amp? Any outboard transformer couple P/S?

Sigma/404 v. Lambda Nova Sig comparison:
Any ideas on how to further tweak the modded Sig Pros? Any thoughts on this 'trimmed inner foam' thing?
Spritzer is your man for both questions I think.

He did a number of tweaks to the SRM-T1 back in 2006/07 and I'm sure he'll have a record of what worked best.

Similarly, he has a good track record with modding many of the Stax frames/drivers and has experience with the Sigma 404.

I'd suggest shotting off a PM to him.
post #395 of 472
Quote:
Originally Posted by bonemaster77 View Post
Need some info, folks. Please give me some direction or answers if you have them.
Sigma/404 v. Lambda Nova Sig comparison:
A pr. of Lambda Nova Sigs came w/the SRM-T1 deal. I like the LNS's but find them to be 'tonally balanced' too far to the high end making the highs painfully strident/edgy. This isn't a matter of all high no bass. I hear the full range reproduced.

On the other hand, I bought a pr. of minty Sig Pros and they sounded dull/dark/lacking a proper amount of shine in the highs (full overtone series).

So, I had YAMA's do the conversion with a pr. of 404's I found (side note: the flat brown cables on both the LNS's and the 404's was the same width--did I get snookered on the 404's or did I get a re-cabled LNS?). Now that improved the Sig Pros--plenty of bass and low-mid (don't see a need for thicker pads for a better seal), but the mids sound like they’re in a hole and the highs are better but still lack a little shine/sparkle from missing the full overtone series. YAMA's had asked if I wanted to have the interior hard foam replaced as stock or trimmed down.
The LNS came with the wide flat brown cable as per the 404 and the Omega 2 - you have the original cable type. The Sigma Pros had the same thinner cable as the Lambda Signature IIRC. I have the Omega 2 Mk 1, Sigma 404s and the LNS. The LNS is brighter than both the Sigma 404 and the Omega 2 Mk1, with the Sigma 404 being the dullest of the 3. The Sigma 404 has less bottom end than the LNS which has less again than the Omega 2 Mk 1. Vocals on the Sigma 404 are superb and IMHO, unbeatable. Sensitivity of the Omega 2 Mk 1 and the Sigma 404 are about equal and much less sensitive than the LNS. The LNS could well sound at its best powered by a tube Stax driver (such as the T1 or T1S, the 006t or the 007t) to tame a little of its mild brightness. The Omega 2 Mk 1 and the Sigma 404 need at least an SRM 717 to power them. A tube Stax tube energiser is struggling (unless you have a SRM T2).
post #396 of 472
The T1 is identical to both the T1S and T1W, it's just an earlier version. The S and W even use the same PCB. I do prefer T1 to the other variants since it is a bit smoother but the difference is very small.

I did do some mods such as replace the main PSU caps (though that was more for long life as the amp was used 24/7), rewired the entire amp with silver and swapped the input connectors for WBT silvers. That made the amp more transparent but can't overcome its biggest faults, i.e. lack of power and the wrong tubes for the job. The Sigma's are very power hungry beasts (almost as much as the Omegas) so a Blue Hawaii would be a good upgrade. You could build an ES-1, or some of the new designs which are emerging, but none of them are as immune to the load as the BH.

If any of you are going to CJ next weekend, try to listen to a normal bias Sigma off the BHSE.
post #397 of 472
If I put the 'good' tubes in (and re-bias the amp of course), does it worth to replace the wiring and the RCA jacks after that?
post #398 of 472
Guys--thanks for all the good stuff. I appreciate it!

I conclude that while certain part upgrades will offer 'finesse' to the sound, only a significant boost of the P/S (to enable use of better tubes) will be the real improvement.
--How does this help to flatten the perceived frequency response/tonal balance that many others have also noted as 'deficiencies'?
--Has anyone considered designing/building an outboard/separate P/S for the T1, I guess like the T2?

Also, no comments on the inner foam trimming issue? Odd that Tats would bring that up as something he hears w/some frequency.

Wish I COULD go to LA for CANJAM, but I'll be in New Hamp and NY on business and won't be able to swing it.

Finally, if any of the 'part replacement/tweaks' and schematics are 'public domain', can anyone provide a link thereto? Spritzer's a great guy, but he DOES say he's overwhelmed w/PMs, so...

Thanks all. Keep the comments coming!
post #399 of 472
Quote:
Originally Posted by padam View Post
If I put the 'good' tubes in (and re-bias the amp of course), does it worth to replace the wiring and the RCA jacks after that?
I should have been clearer, I didn't mean tube brands but rather tube types. The 6CG7 is a bad choice for this role since it is only rated for 300v on the plate and limited power output. Driving tubes out of spec is never a good idea but Stax have managed a compromise so the amps don't go through tubes like hard candy (like the ES-1 does and the A-10 could do). There is not much that Stax can do about it though as there aren't many high power dual triodes out there in current production in a noval envelope. The 6SN7 is the same basic design but much larger (octal base) and while the ECC99 is a brilliant tube there is only one manufacturer and no NOS tubes.

Quote:
Originally Posted by bonemaster77 View Post
I conclude that while certain part upgrades will offer 'finesse' to the sound, only a significant boost of the P/S (to enable use of better tubes) will be the real improvement.
--How does this help to flatten the perceived frequency response/tonal balance that many others have also noted as 'deficiencies'?
--Has anyone considered designing/building an outboard/separate P/S for the T1, I guess like the T2?
If you increase the power of the amp then the FR will become flatter by design. As the impedance of the drivers goes down then the harder it is for the amp to maintain a stable output voltage into said load and the voltage drops.

The T1 and T2 have nothing in common so simply taking the transformer out of the main chassis and the unregulated PSU will not do anything since the whole output stage would have to be redesigned with different tubes.

An amp has been designed which is based on the 007t but moar of everything. It's still in the prototype phase (a set of boards is headed my way ) and I'm not sure what is planned after that.

Quote:
Originally Posted by bonemaster77 View Post
Also, no comments on the inner foam trimming issue? Odd that Tats would bring that up as something he hears w/some frequency.
Do you know if they meant the foam that goes with the earpads (the mesh backing) or the yellow mineral wool? If it is the latter then I also trim it down a bit when I'm working on Sigma's since that's what Stax did over the life of the product. The first units were filled with wool, stuff all around the driver etc. but the newer ones only used the larger slabs.

Quote:
Originally Posted by bonemaster77 View Post
Finally, if any of the 'part replacement/tweaks' and schematics are 'public domain', can anyone provide a link thereto? Spritzer's a great guy, but he DOES say he's overwhelmed w/PMs, so...

Thanks all. Keep the comments coming!
The T1 series is still being sold as the 006t and the 007t isn't far off in terms of design so the schematic isn't out in the open. At least I haven't seen it though it is a simple enough amp.

As for the PM's, send me something interesting and I'll respond. Basic questions about what some Stax costs or some basic technical questions go unanswered.
post #400 of 472
Spritzer said: “Do you know if they meant the foam that goes with the earpads (the mesh backing) or the yellow mineral wool? If it is the latter then I also trim it down a bit when I'm working on Sigma's since that's what Stax did over the life of the product. The first units were filled with wool, stuff all around the driver etc. but the newer ones only used the larger slabs.“

He was NOT referring to the mesh & foam in the middle of the earpad (although he DID as if I wanted that foam removed--any benefit with that?) but rather referred to the yellow foam that you see through the 'grating' of the cages.
Since he DID replace this foam, I'm guessing that it is the 'slab' material you mentioned. Is there any benefit to trimming this 'slab' down? The S/N on mine is 08266.

As always, thanks!
post #401 of 472
I removed it mostly to make the phones easier to reassemble (I strip them all the way down) but I found the phones a bit less bloated with less damping. On any of the Sigma's that is a very good thing.

The earpad mesh has no bearing on the sound but is uncomfortable for some.
post #402 of 472
Guys what do you all think of the SRM-1? I understand it is from around 1979, is it a worthy driver? Thanks.
post #403 of 472
Not bad, but the later ones like SRM-1/MK2, preferably with "C" serial number (upgraded parts) are better because they are good for most of the Pro bias headphones as well. If you want to drive a normal bias Lambda, I think the SRM-1 is a good budget choice.
post #404 of 472
Thread Starter 
Back from Canjam 2009 in LA. I was pleased to see one gentlemen;s display of the Stax Sigma Pros and Sigma 4040s. Others had the Omega 2 and New Omegas as well as the 4070s. I was disappointed that the Stax representative from Gardenia, CA- which is really close by- did not have an exhibit room. Still, all and all there were plenty of Stax Headphones and Stax Amps in attendence. Scottsmryc
post #405 of 472
It seems that I am going to join the club as well. Here is mine (still sitting at home and waiting for me to test it)
LL
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