[John Buchanan]

Kev,
some great information here. Thanks for posting. Let us know what you think of the sound compared with what you remember of the pre-upgrade Sigma. Even that sounds superb - it just seems to get you into the music somehow compared with a SR 007 or a Stax Lambda Nova Signature.

 

[Duggeh]

The SR-202 drivers are definately black.
Picture Linkatron

 

[John Buchanan]

Quote:

Originally Posted by Kev Picture of Sigma driver removed. Let me know if you guys want more.

Kev, I would be very interested in more pictures - feel free to email me as I would prefer higher res pictures. How do they sound now?

 

[Kev]

Sure. I'll take some pictures and send them to you. By the way I picked up two replacement cords, two sets of SR-202 drivers and a headband from the guy who is selling the Canadian stock on eBay. I plan on making a quadraphonic/surround stax earspeaker. I'll start a new tread for that. Not sure to make a box type design like Sigma where I would have a driver in front/back or a triangle design with two drivers at an angle. What do you guys think?

I have put all my quadraphonic 8 tracks to reel and I'm in the process of mastering them at 24bit 96khz using a Fostex DVD-RAM recorder. I built the 8 track reel player from an Akai quadraphonic reel deck. The reel heads are different from and 8 track head. They sound like a reel not like an 8 track!!! Incredible!!!

Oh. The guy who bought Sigma Pro drivers that is upgrading his normal bias pair wrote the following:
"I have now had a look into the pro´s the answer is there is no silistors just connections to 3 wire, but the have a simple plastic isolator around the connector for secure resasons.

I think that i just use the old cable for the non pros and simply remove the pin 6 so it fit into the pro driver."

 

[John Buchanan]

OK dudes, I'm taking one for the team - I finally sent the Sigmas off to Accutech for the Sigma -> Sigma Pro upgrade, using SR202 drivers and the 404 cable. Then I can use the 717 with the Sigmas. Looking forward to this!
I chickened out of doing the upgrade myself, as I didn't want to destroy the cabling and my soldering skills are non-existent. Thanks for the info however Kev. How do they sound?

 

[John Buchanan]

Sigmas now Sigma Pros and winging their way back to Perth. Woo Hoo!!

 

[Duggeh]

Looking forward to what you think of them John. Hope they turn out to be worth the trouble.

 

[edstrelow]

Quote:

Originally Posted by John Buchanan OK dudes, I'm taking one for the team - I finally sent the Sigmas off to Accutech for the Sigma -> Sigma Pro upgrade, using SR202 drivers and the 404 cable. Then I can use the 717 with the Sigmas. Looking forward to this! I chickened out of doing the upgrade myself, as I didn't want to destroy the cabling and my soldering skills are non-existent. Thanks for the info however Kev. How do they sound?

Any reason why you went for the 202 drivers rather than the 404?

Not that I think it will make a great deal of difference. They have the same bias and diaphragm thickness so they should sound like the Sigma/404.

Too bad you don't have a low bias Sigma for comparison. As I have said many (too many) times, they do some things good that even the high bias Sigmas don't.

 

[John Buchanan]

I bough a 202 driver set from the (I presume) Harold Mori****a estate sale. Was going to sacrifice the Lambda Nova Signatures originally, but I suspect the 202 drivers may be as good or better than the LNS drivers - they are at least as thin. Also asked for the 404 cable to be placed. I want to de-amp - have an SRM 1 Mk 2 Pro that I want to sell or give to my father. Couldn't find any cheap Sigmas around or would have kept the low bias ones, Yamasinc/Accutech were very helpful, totally unlike the local (relatively) Sydney distributors, and most of the modification time has been international travel
I'll get back to you.
Newsflash - they just arrived back and will pick them up this arvo. Left Australia 28/10/06 and returned today - excellent!

 

[edstrelow]

Whoee! The excitement mounts. There have not been a lot of low bias to pro conversions of Stax phones in the last few years, although for some years Stax and its dealers would modify the Sigmas this way at a fairly reasonable price, about $200.00 in the late 80's. This practice had stopped long before I modded my low bias Sigma with 404 replacement parts earlier this year. In fact it appeared that I had the only Sigma pro in existence with the recently introduced thin drivers and low capacitance cord.

While I liked the possibility of having a unique Stax, I felt that my little phones were rather lonely and needed to know that there were others like them in existence.

I will look forward to you observations about the sound of these phones. I recall that my set sounded a bit muffled out of the box but within about an hour were starting to sound like what they would eventually settle down as.

Too bad you can't compare them to the low bias Sigma , but a direct comparison with the O2 will be nice.

 

[John Buchanan]

Muffled Sigmas - get outta here! They always sounded a trifle muffled to me, but the lack of sibilance!! It will be great to compare them with the O2. Not many of us here have done this conversion. Have to wait to collect the car from service before 1.5 hour drive to collect them.

 

[edstrelow]

I will be especially interested in the comparison with the Omegas. So before
John Buchanan gives us the real facts, let me make some predictions.

Like many Stax fans, the Omegas seemed to be the phones to get, although I have still not heard them. Also they are so damn expensive that they are hard to slide through a hole in the family budget. Even buying up an old Sigma on Ebay and modifying it with all new 404 parts was a fraction of the cost of a new Omega. And then quite a few people have said they didn't even like the Omega, so...

But there are always some naysayers, one of my friends didn't like the Orpheus system, couldn't see what the fuss was about.

Still, the Omega would seem to have some things going for it that should translate into an improvement over the older designs such as the Sigma and Lambda.

In some respects they resemble the latest Lambda pros, the same thickness of diaphragm, and a low capacitance cord like the 404, I believe.

However, they appear to have a much more solid transducer capsule, which should translate into an increase in clarity and punch compared to both Sigma and Lambda pros.

The Omegas are supposedly less efficient than the Lambda pros, but I would imagine them to still be more efficient than the Sigma pro. The Omegas appear to seal around the ears. The Sigma is a wholy open design, open back, open sides and no direct coupling to the ears at all. Sometimes I am amazed that the Sigmas work at all. Efficiency should translate into some increase in clarity, the drivers of the Sigma/pro have to be driven harder, meaning more intermodulation distortion. The lack of coupling should also mean less deep bass for the Sigma/pro designs. Certainly this is so comparing my Sigma 404 to the Lambda 404.

Many Omega listeners call it "dark," which I suspect translates as bassy. Few seem to find it as sibilant as the various Lambda pros. All the Sigma designs are somewhat dark, and most people comment about a mid-bass hump probably caused by resonance in the enclosure. I find the hump pretty much the same between the old Sigma Pro and the Sigma/404. The hump seems less well-defined with the low bias Sigma, possibly because the low bias system has more ambience of all frequencies, which tends to cover the hump.

The latest Sigma mods, have more treble than the the basic Sigma pros, at least that is so for my Sigma 404 versus low bias and older Sigma pro, but are still no-where near as grating as the regular Lambda pros can be with a bad source.

Of course what sets the Sigma apart from virtually every other phone ever made is the positioning of the transducers ahead of the ear and at 90 degrees to the ear. While not a complete solution to the problem of making headphones makes sounds like objects in real space it does give rise to more of a perception of sound "out there" and in front of the listener than conventional phones. Even my 404's can make sound appear out of the head to the sides, but only the Sigma does this to the front. And even when the forward projection is not convincing they give a pleasant sense of an auditory at least somewhat ahead of a line between the ears.

So I will make my prediction:

Omega: better deep bass, better clarity and slam, frequency response somewhat similar to Sigma/202, but less/no mid-bass hump.

Sigma: the elusive quality of sound caused by the projection of sound 90degrees past the ear rather than directly into the ear canal, giving rise to a sound image or soundstage more forward and ahead of the listener than in the head. Somewhat closer in frequency response to th Omega than the Lambda

 

[spritzer]

You are correct on some points. The Omega's are dark i.e. they lack a prominent HF extension. It's there but when they are incorrectly mounted to the head the bass can overpower anything else and drowns out the HF. I have been working on the fit issue this last week and the more I bend the metal bands to make the transducers parallel to the head (they are stock at a steep angle), the better and more balanced they get. The bass is there but it isn't as overpowering.

They Sigma Pro's have a HUGE midbass hump, are a bit soft on top and they are a bit easier to drive then the Omegas and all of the Lambdas are much easier. The Omegas need a lot of voltage sou they will sound dull and lifeless in comparison with most other phone if they aren't volume matched.

The Omegas finally deliver a better headstage then the Sigmas with none of the drawbacks and the are especially good with the depth and height of the headstage. The headstage of the Sigmas is a lot more diffused.

The main problem with both the Sigmas and the Lambdas is the resonant housing. The Omegas shake in your hand when music is playing demonstrating the superior build quality. They also form an airtight seal perfecting the coupling to the head. if you break the seal you get mad bass...

For me the Omegas are the top of all headphones, completely crushing the He90 in all areas except perceived HF response. Their problem is that they have a unique mounting system so they need a bit of work to be perfected. It only took me 3 years

 

[John Buchanan]

Ok initial impressions are in for the 202/Sigma with 404 cables:
1. Not much better deep bass than the original Sigma - obvious when compared with the Omega 2 which is really good in that region.
2. Reduced mid bass hump - this was quite obvious on the Sigma, and appears to be flattened out quite a bit on the 202/Sigma. This makes the 202/Sigmas sound less bass prominent, but less resonant.
3. The midrange is still superb - noted lack of sibilance similar to the Sigmas, and much less than the Omega 2.
4. Treble has been mucho extended in the Sigma/202 and, as I had hoped, without any increase in sibilance
5. Huge increase in dynamics. The Omega 2 is better, but the Sigma Pro is still excellent.
6. Slight L/R imbalance - suspect that 303 and 404 use selected, gain matched 202 drivers.This is what separate volume controls are for.
7. Much less efficient than the Sigma, and really needs the 717 to drive it. I suspect the original Sigma Pro was more efficient than this, as it used the more efficient Lambda Signature drivers.
The modification was all I had hoped for and so far am very happy. I would recommend it to any Sigma owner. The Omega 2 generally sounds better, but that lack of sibilance wins me over every time!
I am not too into sounstaging effects, so that part can wait.

 

[edstrelow]

I certainly concur about the increase in treble with the 202 or 404 mod versus the low bias Sigma. I can add that treble for the modedd Sigma is increased not just in comparison with the low bias Sigma but even in comparison with a regular Sigma pro.

The change in overall dynamics is basically the result of going to high bias operation. I don't notice any obvious difference in sensitivity between my Sigma/404 and the older Sigma pro, but the change is fairly obvious by comparison with the low bias Sigma. I wasn't aware of the reduced efficiency of the pro models, but then I do not have an amp capable of running both, I have to use different amps for them. This is probably not a surprising result since the pro stators are further away from the diaphragms and may need more juice to get the diaphragm moving.

The flip side of having greater dynamics is that there is less ambience. Musical signals, such as a solo instrument, stand out more from the background with the pro system and the background, ambience is less prominent. Sometimes I like the higher ambience levels of the low bias Sigmas. It's a different musical presentation. Maybe that and the fact that the amplifier is not driving as hard because of the greater efficiency gives th Sigma its distinctive signature.

However, if I had to do the desert island thing and chose just one Sigma, I would chose the Sigma/pro/404 over the over models and the reguar Sigma Pro over the low Bias Sigma. However if you have a choice, the low bias Sigma is a nice contrast. For me, it sits in a different system in a different part of the house and offers a nice change of pace, allowing me to hear music in a different presentation, rather like going to a different concert hall.

Glad to hear that you are happy with the result. I would be curious as to what you think about the forward projection aspect of the Sigmas vs the Omegas.