The Stax thread (New)

[dvb-projekt]

Quote:

Originally Posted by ericj /img/forum/go_quote.gif The SRD-X Pro is probably an SRD-X with a different bias circuit - in which case, it's a fairly pedantic car radio chip amp driving a pair of small transformers. What do you need a schematic for? I still need to trace out the bias circuit from my SRD-X.

I would like to make a new case with a new bigger pcb and tweak it up a bit.

 

[zigo]

Please, somebody knows the output impedance range of srd7-sb?
Not the 8ohm input, the output.
tia

 

[ericj]

Quote:

Originally Posted by dvb-projekt /img/forum/go_quote.gif I would like to make a new case with a new bigger pcb and tweak it up a bit.

Like i said, the SRD-X consists of a mediocre, 1979 chip amp - Which is to say a low-power speaker amp built with parts intended to go in entry-level car radios - and a pair of small transformers. And a bias supply.

The only parts of that with value are the bias circuit and the transformers.

Rebuilding the existing power amp on a different board would be a fool's errand. It needs replacing.

The volume pot, by the way, has dissimilar decks on it. One of them has less resistance than the other, and that little adjustment point on the side for adjusting the channel imbalance tweaks a trimpot on the board that adds more resistance to the lesser path.

Replicating that functionality would be foolish as well. So, out goes the existing volume pot.

What i recommend - and plan for myself - is replacing the power amp with a small, potentially DIY class-D or class-T amplifier.

So then what we need is a wiring diagram of the transformers and bias supply, and nuts to the original amp circuit.

I'm here to tell you: These do not exist. We don't have them. I'd like to have them, but will probably have to make them myself from my SRD-X, which won't have the same bias supply as your SRD-X Pro.

 

[dvb-projekt]

Quote:

Originally Posted by ericj /img/forum/go_quote.gif Like i said, the SRD-X consists of a mediocre, 1979 chip amp - Which is to say a low-power speaker amp built with parts intended to go in entry-level car radios - and a pair of small transformers. And a bias supply. The only parts of that with value are the bias circuit and the transformers. Rebuilding the existing power amp on a different board would be a fool's errand. It needs replacing. The volume pot, by the way, has dissimilar decks on it. One of them has less resistance than the other, and that little adjustment point on the side for adjusting the channel imbalance tweaks a trimpot on the board that adds more resistance to the lesser path. Replicating that functionality would be foolish as well. So, out goes the existing volume pot. What i recommend - and plan for myself - is replacing the power amp with a small, potentially DIY class-D or class-T amplifier. So then what we need is a wiring diagram of the transformers and bias supply, and nuts to the original amp circuit. I'm here to tell you: These do not exist. We don't have them. I'd like to have them, but will probably have to make them myself from my SRD-X, which won't have the same bias supply as your SRD-X Pro.

Thanks for the information Eric. You´re right, i leave everything as it is.

 

[spacemanspliff]

I have had the Stax Lambda normal and an SRD-7. Loved it. I see Salt Peanuts has a Stax SR-Lambda Pro & SRM-1/Mk on the FS here. What are the differences b/w the two combos sonically?

Cheers!

 

[HeadphoneAddict]

My new SR-404LE out of my GES or my Qinpu A-3 > SRD-7 Pro sounds pretty good. Started burn-in around 3PM. Will keep you updated. So far on Bella Sonus and Bink Audio Test CD the bass is strong down to 20Hz - yippee!

 

[spacemanspliff]

Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif My new SR-404LE out of my GES or my Qinpu A-3 > SRD-7 Pro sounds pretty good. Started burn-in around 3PM. Will keep you updated. So far on Bella Sonus and Bink Audio Test CD the bass is strong down to 20Hz - yippee!

20hz? How? Is it the amp? I thought they rolled off around 32hz?

 

[El_Doug]

the beginning of rolloff does not necessarily correspond with the point at which the level drops to inaudibility

 

[spacemanspliff]

Ok. Not to be repetitive. I am going to research now that I have an hour. Still, if anyone has heard both of the below combos, please give me your opinion. I have a borrowed pair of V4 Darths and they sound excellent but I fear they are just not quite resolving enough in the details area. Very fine dynamics though. The bass is certainly improved in its level. Just barely intrudes on the mids now.

I have had the Stax Lambda normal and an SRD-7. Loved it. I see Salt Peanuts has a Stax SR-Lambda Pro & SRM-1/Mk on the FS here. What are the differences b/w the two combos sonically?

Ok looks like the pro is more detail oriented and has a bit less kick than the normals. Tell me if I am wrong please.

Cheers!

 

[edstrelow]

Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif My new SR-404LE out of my GES or my Qinpu A-3 > SRD-7 Pro sounds pretty good. Started burn-in around 3PM. Will keep you updated. So far on Bella Sonus and Bink Audio Test CD the bass is strong down to 20Hz - yippee!

I would sure like to know what these sound like compared to a normal 404. Do they have foam behind the drivers? If so you might want to try them foamless.

 

[spacemanspliff]

Quote:

Originally Posted by edstrelow /img/forum/go_quote.gif I would sure like to know what these sound like compared to a normal 404. Do they have foam behind the drivers? If so you might want to try them foamless.

He knows all about foamless. Bluto has my old Lambda normal foamless. Those are killers. I want them back btw. lol

 

[HeadphoneAddict]

With the SR-404LE I think a lot of the tizzyness of the SR-Lambda Signature treble is missing and there is very little upper midrange etch, the mids are more forward than the SR-Lambda Lambda Pro or Signature, and the bass is punchier and more dynamic than my SR-Lambda (normal bias).

There is a thin layer of foam behind the driver on the SR-404LE, and while I enjoy Blutarsky's SR-Lambda with no foam, I don't want to muck with mine or these right now.

And, as far as the bass - the bass at 25Hz is almost as strong as the bass at 31.5Hz, while the bass at 20Hz is probably about 3-4dB down from 31.5Hz which to me is pretty good for an open can.

 

[Michgelsen]

Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif With the SR-404LE I think a lot of the tizzyness of the SR-Lambda Signature treble is missing (...)

Is this a good or a bad thing?

 

[HeadphoneAddict]

Quote:

Originally Posted by Michgelsen /img/forum/go_quote.gif Is this a good or a bad thing?

Good?

 

[Sherwood]

Very good. Tizziness is a universal evil.