John Buchanan

Ed, I would have been happier saying the same as you. There is certainly not a whole lot of difference between the two Sigma high bias. And I got this one for a lot less money than a Sigma normal and going for the conversion. As you have said many times, it's interesting how these Lambda drivers behave in a different shell. Am getting some original Sigma ear pads to apply to the Sigma/404 and then I can do a rematch. I should have kept the SRM-717 and the SR-007 Mk1, but the room was starting to look like a hifi showroom - check out my profile.

Just replaced the old (mesh disintegrated) Sigma Pro pads with new ones - the mineral wool stuffing was catching the edges of my ears. The set looks brand new now, and is sounding fantastic. The comments I made about diffuse field equalisation of a Lambda apply to this phone in as well - high hats in particular sound very natural, rather than the pressure-pak hiss sound !

I had an SRX Mk3 and didn't like it. Deficient bottom end - too bright. The original Sigma replaced it without any regrets whatsoever. The Sigma Pro or Sigma/404 are even better. I've never even seen a Gamma. The Sigmas may have Lambda drivers, but they don't sound like Lambdas.

Stax Sigmas high bias earspeakers compared – Pro vs Sigma/404. These 2 Sigma high bias phones essentially differ in 2 main ways. The headphone cable used for the original Sigma Pro was the same as the one first used on the Lambda Signature – not as wide as the one used for the Sigma/404 hybrid, which was first seen on the Lambda Nova Signature. The drivers are different also – the Sigma Pro uses the reported 1 um Lambda Signature driver, whilst the Sigma/404 uses the (2 generations) later 1.35 um drivers first seen in the Lambda 404. Otherwise, the shells of the 2 earspeakers, apart from minor colour variations, are identical. The Sigma Pro appears to be slightly more efficient. In my set up so far, the two have been compared through the Studer D730 -> Apogee Mini-DAC -> Audio Research LS5 Mk2 -> Suder A68 -> Spritzer Pro modified SRD-7 bias + transformer box. As seems to be the order of the day, the results are not what I expected. The Sigma Pro is far better than its reputation and bests the Sigma/404 in a couple of areas. Firstly, the deep bass is slightly more evident and the mid bass is much tighter and less resonant. Bass drum has slightly more punch rather than smeared thud. This has been one of my only criticisms of the Sigma/404. The midrange is about the same with both, but the treble is slightly more evident with the Sigma Pro. It’s close to a line call there, however. As for dynamics – the Sigma Pro does dynamics somewhat better than the Sigma/404. The Lambda Signature driver/cable just sounds a little faster than the 404 driver/cable. This tends to alleviate some of the complaints about a mushy low end. The original Sigma low bias was far too rolled off at the top end in particular, despite the magical Sigma midrange being present there. It appears that either the Signature or 404 driver implants are a successful remedy to this, and gives a phone that had huge promise a push into reference territory. In summary, despite every single report to the contrary, I’m loving it! Flame suit on, hearing aid batteries fully charged LOL. Stax SR-009? Who freakin' cares!

Go Birgir!!!

Ed, my normal bias Sigma was sacrificed many years ago to the Sigma/404 transformation. So it will only be a Sigma Pro vs Sigma/404. What were other people's impressions of the Sigmas at the meet. So few people have heard them. I would expect most people would be unhappy with the Sigmas (far too dull) compared with the Sigma/404s. I run my phones off the Stax SRM Monitor, which is basically an SRM 1 Mk2 with a switchable diffuse field equalizer.

It's the earpad netting that's missing, I believe. The photos show no netting and plenty of mineral wool. I have a spare set of earpads for the Sigma.

A Stax Sigma Pro is now on its way to sunny Perth. Couldn't resist, so a Sigma Pro vs Sigma/404 comparison will eventually happen. Happy days!

The one I heard in Melbourne was far better than the SRA12s that I had at the time. Terrific amp, IMHO.

The Led Zeppelin CDs are all essentially either the original masters (Barry Diament except for Led Zeppelin IV which was done by Joe Sidore) or the George Marino remasters. The earlier masterings are all good as well as the remasters. King Crimson - avoid the so called Definitive Edition CDs made before the 30th Anniversary Editions. The best I can say about those previous editions is that they were done from inferior tapes with lots of noise reduction. The 40th Anniversary Editions have remixed as well as a remastered version on most of the sets. They are very good.

Hmmmmm, let's see .........looking through the collection........ - Aqualung DCC compared with the 25th Anniversary CD - The DCC features the return of recording studio ambience that was reft away from us with the 25th. - Creedence Clearwater Revival CDs on DCC or Analogue Productions compared with the current remasters - apparently a tough call to remaster between getting the voices right and having a drum kit that is a bit dull, or getting the drum kit right and having overly sibilant vocals. The DCC/APO path was the former, thankfully. - Bad Company and Straight Shooter on Audio Fidelity - Audio Fidelity better than Barry Diament better than remastered versions. I try and do a comparison between any version that he has done, and in no case has it turned up inferior to anything before the Steve Hoffman version was released, and in most cases, is superior to anything since. I guess his listening values correspond to mine - boosting the treble and bass is not a good thing unless the original album was seriously deficient. Stay away from noise reduction, find the true original stereo master and make the album's maximum peak level less than 100% modulation. All sensible stuff for great sound. Deep Purple's "Made In Japan" is close to a line call, with the DCC just winning over the older Warners CD. Compared with the 25th remaster, the DCC and old Warners are far better. Even Cream's "Wheels Of Fire", whilst no sonic marvel, is still best heard on the DCC set. It was released by DCC in 1992! Call me a fanboy, but I'm happy to justify each comparison. MoFi remasterings are a different call - I still prefer the current Universal USA CD of Bluesbreakers over both the MoFi attempt and the mono Audio Fidelity CD.

Stax did this with their ED-1 - an attempt to bend the frequency response of their Lambda Professional Earspeaker to the ideal diffuse field frequency response.

I have a boof head and the adjusters are near the bottom of their travel on the Lambda Nova Signature. Please note that the Lambda Pro headphones have a different arc assembly from later phones - and the force exerted on the sides of your head was increased in later models. The pins that attach the arc assemblies to the cases are much smaller diameter than more modern Stax, so a new arc assembly won't fit in Lambda Pro cases, unless the metallic pin receptacle is removed gently. I find the reduced side pressure of the Sigma very pleasant compared with the greater clamping force of the Lambda Nova Signature.

I've heard this happen to phones in my last house due to evaporative air conditioning increasing the humidity to an extreme level. The phones would occasionally play at a low volume with distortion. Turned off the a/c for 24 hours and they were back to normal. The Sigma 404s were the only ones affected, possibly because the transducers lie parallel and close to the shelf on which they rest when dormant (and provide an easy area for water condensation??), whereas the Lambda Nova Signatures rest with the transducers perpendicular to the supporting surface and were never affected.

Ya need a pair of F83s instead! Wish I'd had enough money for those back in the day. Ah well, the 989s will just have to do LOL.

Interesting view - I have found that the SRM-717 wasn't a patch on the SRD-7/Studer combination. It sounded OK in isolation, however. I'm not so sure about pleasant distortion either. But, I haven't heard a BHSE either.

OK - putting the neck on the chopping block here! I have the SRD-7 with the Spritzer Professional bias board, so, in effect, an SRD-7 Pro. Love the sound with the Sigma/404 and driven by a Studer A68. The bottom end is nicely in control (as Birgir has said happens with upscale amplification ala Blue Hawaii SE or that ilk), and there is more of the power that these earspeakers have in spades. They seem to convey the "oomph" of the performance much better than any other Stax I've heard. Although the Lambda Nova Signature/SRM-Monitor is probably more technically neutral, this combination seems to get a natural sound out of most recordings, just as Naotake Hayashi mentioned. Piano and vocals through this set just sounds real - IMHO not even the SR-007 Mk 1 could do that as nicely - without any midrange stridency or upper midrange cymbal emphasis. Someone mentioned the distortion in the SRD 7 - not sure what he/she is talking about. Can't hear any problems there. Measurements may prove me wrong however, but that's fine. Currently listening to Jacques Loussier's "Baroque Favourites" - piano sounding live and the drum kit is reproduced well with no unnatural cymbal emphasis and with great speed also. I'd love to hear a super deluxe version of the SRD-7!

It's not well recorded, sure, but the wow is only really heard on Changes through speakers rather than headphones (Studer D730 -> Apogee Mini DAC -> Studer A68 -> Stax SRD-7 Pro -> either Stax Sigmas or Quad 989s for those interested). Similar things noticed on Studer -> Audio Research LS5 Mk 2 -> Audio Research VT130). If I was mixing this album solely through headphones, this would have been missed.

LOL - Quad 989s actually.

The wow is definitely there - quite obvious in the piano notes, but it's hardly audible on phones, compared with speakers. It sounds like a recording on a home tape recorder.

Next suggestion. Makes no difference, as also very evident when using both solid state systems.

This isn't strictly limited to Stax phones, but I was wondering why the terrible wow in the piano on masterings of "Changes" from Black Sabbath Volume 4 is hardly noticeable on phones and mind blowingly annoying on speakers. Any theories?

According to Spritzer's dissection of the 507s, the new drivers are not glued together then attached to the base plate with double sided tape. They are compression fitted together by screw tension applied to a housing box. There is nothing to screw the housing into on the standard Sigma base plate, although transplanting a 507 base plate and housing/driver sounds workable if the new base plate if the same size. I guess by then, the cost is starting to get close to $2000 ($900 for the 507, $800 - 900 for the Sigma), and you are in O2 territory.

You might want to listen to the Sigma/404s. There is no honkiness in the upper midrange that I have ever heard. In my opinion, the 404 upgrade was ALL good and without any drawbacks (less of the upper bass hump, more low bass, less treble roll off and retained the magic mids that do piano and voice so well). They are a very addictive phone. The SRD-7 -> Pro is what I use and they sound great. The SRM-Monitor also sounds very nice, but can't hammer the phones like the Studer A68 or the Audio Research VT130 through the SRD-7.