STAX SIGMAS COMPARED, LOW BIAS, SIGMA PRO AND SIGMA/404

[edstrelow]

There should be a lot of bass with these phones although it does not go as deep as the comparable Lambda.   I would guess the wrong type of wool is in this set.   Some while back I found that if the Sigma drivers are not enclosed in their "boxes" there is no bass worth mentioning.  If the Sigma box is sealed (by tape)  the Sigma becomes very echoey,  Somehow Stax worked out just the right amount and weight of material to get the Sigmas to work.

 

[chi2]

I've bought two normal bias Sigmas some time ago and one of them had the very same problem. Quite nice sounding mids and highs, a bit aggressive and flat, though, but almost no transmission below maybe 80 or even 100Hz. I thought the diaphragm might have been burned through and out of curiosity I've disassembled the drivers down to the core. The diaphragms of both drivers looked just fine but I suspected (and still suspect) that they have lost some of their conductivity. The second normal bias Sigma sounds just fine but is unable to transmit really low bass notes. And even the Sigma-202 I've built from the one with the defective drivers, while being better at it, has a distinct weakness in the lowest range compared to the Lambda with identical drivers.
 
Quote:

I have a pair of normal bias sigmas and the mids are absolutely beautiful. I love the soundstaging. My only problem is bass. Well, there isn't. They have a little punch but absolutely no extension. I don't think this is normal, but one thing I've noticed is that the previous owner replaced the mineral wool. I assume he replaced it with mineral wool but now I'm not so sure. Does the mineral wool affect the bass performance. If so, is there anywhere I can get some to replace it or an alternative that would be just as good? At first I thought it could be an amping issue since I was previously using a T1S, but I now have an srd7 with a 100 watt amp. I have a lot more drive but still zero bass. I do love everything else about the sound though.

 

[spritzer]

No bass on a SR-Sigma is not normal.  My guess would be that the glue holding the drivers together has cracked so the front and back output is colliding. 

 

[moodyrn]

Thanks for the replies. At this point I really don't know what to do. I may just call the distributor and see what they say. Hopefully it will be as simple as replacing the mineral wool.

 

[John Buchanan]

Quote:

No bass on a SR-Sigma is not normal.  My guess would be that the glue holding the drivers together has cracked so the front and back output is colliding. 

Agreed.

 

[chi2]

While this may well be the case, it wasn't with my Sigma. The glue was so strong, I had a hard time removing the drivers from the baffle and disassembling them.
 
Quote:

No bass on a SR-Sigma is not normal.  My guess would be that the glue holding the drivers together has cracked so the front and back output is colliding. 

 

[moodyrn]

how was the mineral wool in yours?

 

[moodyrn]

I think I've found the problem. I'm listening to them now and when I press them tight on my head, I get bass. It's not a lot but it's definitely more. And I also get more extension. Actually I get more extension than I get quantity. My pads are extremely flat. I knew it would affect bass performance, but I didn't think worn out padd would completely take away the bass.

 

[John Buchanan]

Sigma pads are still available. I use Lambda pads, as they provide a nice seal around the jawline.

 

[schorsch]

Sigma loudspeakers,
 
I just had a closer look at my owner's manual. There is a part that is glued with white paper but it is possible to read it. There is a description of a stand that can be used as a loudspeaker. Have you ever tried? I would like to rebuild it. I qould need a worn out aexample or relatively exact measurements / photos ....?!
I put an album with the manual on head-fi
 
I just had an experiment using the diffuse field equalizer of my SRM monitor with the Sigma. It loses its bass hump - but with some recordings the "room" you're in becomes more unnatural.
 
Regards Georg

 

[plaidplatypus]

The stand was designed as part of the packaging.  It appears to block sound from where your head would normally be and faces the drivers toward the front.

 

[plaidplatypus]

 

[schorsch]

Thank you very much dar plaidplatypus,
 
could you do me a favour and take measured pictures of the total height / width / length and a view of the back part of the stand. I think then I can do it properly.
 
Thanks a lot
 
Georg

 

[gilency]

Well, I have sent my Sigma Pro to Mark Dolbear from www.highendworkshop.co.uk for conversion to Sigma 404.
Can't wait. I asked him whether a 407 conversion would be feasible, he said maybe but he is not sure of the cost of the 407 elements and we don't know if the events in Japan would delay shipment. So I went for the 404.

 

[gilency]

I am happy to anonunce the birth of a new Sigma 404!
Mark, from www.highendworkshop.co.uk did an excellent job on transforming my Sigma Pro to Sigma 404. He is a true gentleman and his work is appreciated.
I have to agree with Edstrelow. Better highs, better lows, less boominess, but a little less soundstage than the normal bias Sigma.
Haven't listened to them much but compared them both, and both are keepers in my book.