Stax SR-507 investigation

[FrankCooter]

These showed up yesterday. Wow! Definitely NOT "your father's Oldsmobile". Major upgrade across the board over the 303's. No more thin, etchy, cool, flat, and uninviting midrange. Much warmer, but and the same time more resolution and better, more precise imaging. There's some real depth and layering of the sound stage. Much improved bass. Having never heard these, and not being a lambda fan, I had some reservations. I gave up my K-1000 for these. I'm happy with the trade. Headband could use to be a bit bigger. I have it maxed out and it's fine for my 7 3/8 hat size. I can see where someone with a really big head might find it uncomfortable. Over all, a big "thumbs up"!

[HeadphoneAddict]

These showed up yesterday. Wow! Definitely NOT "your father's Oldsmobile". Major upgrade across the board over the 303's. No more thin, etchy, cool, flat, and uninviting midrange. Much warmer, but and the same time more resolution and better, more precise imaging. There's some real depth and layering of the sound stage. Much improved bass. Having never heard these, and not being a lambda fan, I had some reservations. I gave up my K-1000 for these. I'm happy with the trade. Headband could use to be a bit bigger. I have it maxed out and it's fine for my 7 3/8 hat size. I can see where someone with a really big head might find it uncomfortable. Over all, a big "thumbs up"!

I gave up my K1000 for my LCD-2, and wishing maybe I had a 507 now. The LCD-2 is uncomfortable, which hurts my enjoyment a lot, although I've gotten used to the sound signature. After a source change and tube change in my WA6, the LCD-2 sound much better than when I first got them. But I like the SR-Lambda and LNS so much, and sometimes I think I enjoy them better.

My son won that WEE at RMAF and so we sold his SR-Lambda for an SR-Lambda Nova Signature because he needed a pro bias phone. The LNS sound really good with the WEE through a 12 watt Nuforce Icon, or the WES. They are the closest I've heard to my SR-Lambda, and less bright/etched than I recall my old normal Signature being. I think we made a very good decision. I actually prefer the LNS over my Smegma Pro (woodied gamma pro with SR-007 pads).

[edstrelow]

We all knew this was going to happen but I've taken the SR-507 I got less than 24 hours ago apart. Stax does warn about any and all tampering voiding the warranty so don't try this at home kids.

First off, lets remove those driver housings from the arc assembly (they just pull out like on the two other Lambda designs). Here are the 507 name plates:

Now lest lift up the four corners of the earpads and remove the screws which fix the baffle to the back grill. The baffle just pulls out and we are greeted with this:

Now this is very different from the other Lambdas, gone is the aluminum baffle with the driver glued onto it and now we have a molded plastic baffle with a cradle for the driver to sit in. I'm not sure what plastic it is but it is very stiff. Like I said above, Stax warns about the warranty being void if one tries to tamper with the headphones which would explain this:

Now this just confirms what I thought as soon as I opened up the headphones, the drivers are not glued together but rather just stacked together inside the shell. This is how the SR-Omega is assembled, also the SR-007 and the SR-003. Throwing caution to the wind I remove those 4 screws:

Here we can see the silicone o-ring used to seal the back of the driver and the new chrome look of the metal plate used to hold the dust cover in place. Now it's time to put my hunch to the test and see if the dust cover is glued to the stator:

Indeed it is not though there is some compound used between them. This gives us a direct view of the stators which appear to be coated metal plates, similar to the newer stator design introduced in 1994 with the Lambda Nova Signature. Since I don't happen to have a clean room to do stuff like this I tried to keep the drivers uncovered for as short a time as possible. There are glue pads on the end of the driver so I decided not to mess with them and try my luck exposing the diaphragm. From the side view offered where the connections the diaphragm is still mounted to two solid brass rings like on all the other Lambdas.

Now we take a look on the other side of the driver. With the new earpad design this is quite simple, just use a knife to lift up the cloth cover and you can see the protective mesh:

This is the same silver colored material found on the post 2004 models. The arc is also new and very substantial if a bit uncomfortable for somebody with a gigantic head like me.

They need a lot of parts to make this one work and plenty of screws. None of the cost cutting seen in the post 1994 arc assembly here. Now they are back together and needless to say, they work perfectly.

Do these phones have foam backing like the other Lambdas? I couldn't see any in the pictures.

[spritzer]

Of course they do. All Lambdas have it and don't start that foam making a difference nonsense!!!

[edstrelow]

Of course they do. All Lambdas have it and don't start that foam making a difference nonsense!!!

It's not and it does. I am not saying getting rid of the foam helps all Lambdas, but I prefer my 404 and LNS without it.

Didn't you once report on the effects of different backings? I don't think I hallucinated this.

[padam]

I had two Lambda Signatures side-by-side, both having old pads, one having back foam and other doesn't and heard zero difference between them..

[edstrelow]

I had two Lambda Signatures side-by-side, both having old pads, one having back foam and other doesn't and heard zero difference between them..

That doesn't surprise me or change my opinion. Here's why.

I was first clued to this issue when I replaced the old foam of my LNS. The foam was so old it became thin and crumbly and I don't think it had any impact on the sound. Your sigs would be even older than my LNS. I ordered new foam from the Stax dealer and these foams made the LNS phones sound terrible. It is certainly possible that the old foam was more acoustically transparent than the new foam or just became that way with age. I only caame to dislike foam when I put new foam, which was much thicker than the old stuff.

[The Monkey]

You need to use audiophilephoam.

[spritzer]

Didn't you once report on the effects of different backings? I don't think I hallucinated this.

I did, the wool backing in the SR-Lambda and the Pro's. Even the HF reviewers could hear that difference but the foam makes no difference. If it did then the foam next to the ears would make a vastly bigger difference, same goes for the cloth on the new series. I've tried it and it doesn't have any effect. The foam is just there to obscure the drivers from view.

[padam]

Just came across a with nice pic taken from the driver elements:

Edited February 3, 2011 by padam

[yazz flute]

Any further thoughts on how the SR-507 sounds? I might be getting made.

[spritzer]

It's a very good Lambda but doesn't touch the Omegas.

[n3rdling]

Man, I'm so bummed out that I forgot to listen to Frank's 507 at the NorCal meet. People were saying it had a lot more bass impact than the previous Lambdas. Actually, I ran over to Frank's rig to try to listen to it but he was already packing, so I put them on just to see how the new arc assembly fit me. It was a considerably tighter fit than the older arc assemblies. I'm guessing that since it seems to seal the ears better now, that helps out with the bass (see the FR plots of a Lambda properly fitted vs a Lambda with a bad seal between the ear and driver). Well, that and the stiffer mounting scheme. Do you think there's any truth to this or am I being 'Ed'-ish?

[yazz flute]

It's a very good Lambda but doesn't touch the Omegas.

I've not heard an Omega but it's out of my league. A Lambda is the best I can do I'm afraid. So it seems that I could do worse than the SR-507. It appears to redress some of the shortcomings of previous models?

[spritzer]

The bass is indeed improved but mostly by being cleaner than the usual Lambda. The arc might be a factor and I didn't try one of the older models to check it out. Properly sealed baffle and a much better baffle design would be larger factors to me. Still my old set is in the area so I might have to try this soon...

If you are going to buy a Lambda then you can't go wrong with the 507. I don't care for the fit but my noggin is a bit over sized....

[yazz flute]

Yes, I noticed that the bass of the SR-507 was more defined than the SR-404LE when I compared them.

[crumpler]

Yes, I noticed that the bass of the SR-507 was more defined than the SR-404LE when I compared them.

I agree to that as well. And i personally feel the difference between the O2 and the 507 isn't that great anymore and i am happy as is to stick to my 507s till i get to hear the C32 (hopefully).

[purrin]

From my impressions at the Bay Area meet, n3rling's O2 setup was definitely more accurate. Frank's 507 rig almost sounded like it had a slight U-shaped curve in comparison, with the treble brightness at a higher frequency than most dynamic 'phones - more of an occasional shhh, shhh, than painful ssss, zzzz, ssss, etc. The bass from the 507 on the Eagles live concert CD was very evident and sounded just right for me - for reference, less than Denon / PS1000, more than HD800, and just about where the W1000X's are (though my W1000X's have been dynomatted inside). For a live concert, the 507 bass was definitely convincing and very real.

I'm still on the fence on which to get. I might opt for the cheaper option initially while getting a BH or WES built, or letting the dust settle after the C32.

[monsieurguzel]

I'm still on the fence on which to get. I might opt for the cheaper option initially while getting a BH or WES built, or letting the dust settle after the C32.

Yeah, with the advent of the upcomming C32 as well as possibly a new Stax amp in the next year (or two?) I'm planning on holding off from purchasing a stax setup for now. I really was close to buying a O2 mk1, but it's a pain finding a used pair that is in good condition and has been treated properly. The more time passes, the older a lot of the Mk1s are getting, so it'll be nice having a new flagship from Stax which will be easy to procur and get replacement parts for, etc.

I'm also curious to see how amplification will affect the new C32 and wether or not a BHSE will be necessary (my guess is that it will

[spritzer]

It will be necessary, count on that. Better yet, build a T2...

[monsieurguzel]

It will be necessary, count on that. Better yet, build a T2...

Or maybe by then KG will come out with an even more insane amp...the T2SE

[monsieurguzel]

Actually, what I would really like is a T2 for dummies...if that's even possible.

[livewire]

Actually, what I would really like is a T2 for dummies...if that's even possible.

Me too!

From what I see, you better have all of your technical ducks in a row

if you gonna attempt that build. Definitely not a beginner DIY project.

[FrankCooter]

You guys need to get your feet wet and build something. There are plenty of cost effective, easy to implement, and surprisingly effective DIY designs out there if you dig a little. Make a ton of mistakes, go through a learning curve, and get something successful under your belt before attempting anything as complex as the T2. Got to learn how to crawl before you can run. Consider it the start of a journey.

[FrankCooter]

Considering the huge difference in signal chains, I'm not sure that a meet comparison between my 507's amd n3rdling's O2's means much. What we should have done at the last NorCal meet was plug my 507's into the B.H. and done a direct comparison. Hopefully we'll get another chance. What is pretty clear is that the 507's are substantially closer to the O2's than any previous Lambda. I'm curious what the rest of the updated Stax line sounds like.