[milosz]

Quote:

 
There's more than enough Audio-gd talk in this forum. We don't need it in this thread.

That's an opinion. 
 
The discussion wasn't specific to Audio-Gd, current domain technology is also used by Krell, and, not to put too fine a point on it, the KGSS and KGSSHV dedicated STAX electrostatic direct drive headphone amplifiers.  But, it is probably too technical for many on this forum. 
 

 

[milosz]

For those who do understand the engineering, you may find it interesting that I posted in another forum and to my post Kevin Gilmore replied that he's not interested in developing a current-domain input interface for the KGSS/KGSSHV amplifiers because there's too few folks using CAST-capable sources.  So that effectively kills the idea.
 
Too bad, because current-domain signal transmission  does offer sonic benefits - and who better than Stax users could reap the benefit of greater transparency... I mean, if you spend $2,000 on a pair of SR-007's and $4,000 on a custom-built amplifier, it seems you are the kind of person who wants any additional sonic improvement that you can get.

 

[DaveBSC]

Quote:

Too bad, because current-domain signal transmission  does offer sonic benefits - and who better than Stax users could reap the benefit of greater transparency... I mean, if you spend $2,000 on a pair of SR-007's and $4,000 on a custom-built amplifier, it seems you are the kind of person who wants any additional sonic improvement that you can get.

 
The industry unfortunately often doesn't follow what sounds better or is even logical. There is no reason to use RCA jacks and connectors for S/Pdif, for example. None. We can dream about how much better things would be if there was an industry wide standard for I2S, but coaxial digital with RCA is just silly when BNC is so much better at that job, and it's so easy to implement, and yet the majority of DACs don't have it, especially the more affordable ones.
 

 

[milosz]

Yeah BNC makes a lot more sense for RF like a SPDIF signal.  It's not just the SWR that can occur at an impedance discontinuity that a typical RCA represents, but many RCA's are not all that "tight" and RFI can get in.  Optical via Toslink has some advantages- electrical isolation for one, which can often be a good thing - but in general the optical receivers available aren't really all that wonderful. 
 
With a high-resolution transducer like even an older Stax Lambda Pro, not to mention the SR-007's and 009, you can hear some of these subtle differences. Even the older Stax amps like SRM-1/MkII and SRM-T1 can benefit from really good DACs which aren't struggling to convert a bitstream that's infested with RFI and burdened by reflections from to SWR due to lousy RCA connections.
 
That said, there are some RCAs that work OK.  I'd PREFER BNC, but there are some RCA's that use RG-6 cable and RCA connectors that are very close to 75 ohms. 

 

[Amarphael]

Quote:

Originally Posted by milosz /img/forum/go_quote.gif
 
That said, there are some RCAs that work OK.  I'd PREFER BNC, but there are some RCA's that use RG-6 cable and RCA connectors that are very close to 75 ohms. 

Any specific that you can mention?
 

 

[svyr]

Quote:

Any specific that you can mention?
 

(I got the impression) it seems to do more with the connector impedance and the cable type (shielding)... Not just omgrcaisevilandletsinrfi

as for sonic benefit of ACSS - what is it? Are you sure the 100-db- of thd+n of the analog section (incl will transducers) won't negate it anyway , reducing it to a moot marketing point ?

 

[spacemanspliff]

I am going to rewire the SRD 7SB that I have. I want to get a new stax plug as well as some speaker terminals that can accept banana plugs. Where can I get the stax plugs and is there anything else I can/should use?
 
I just want to do the simple Spritzer mod of wiring the transformers to the speaker terminals and then to the plug. I have the schematics but am unable to find much more on what I need. It looks like I can do all of this without having to solder?

 

[milosz]

Quote:

(I got the impression) it seems to do more with the connector impedance and the cable type (shielding)... Not just omgrcaisevilandletsinrfi

as for sonic benefit of ACSS - what is it? Are you sure the 100-db- of thd+n of the analog section (incl will transducers) won't negate it anyway

, reducing it to a moot marketing point ?

Cables- there are some RCA cables sold by Cableslimited on eBay that are made of RG-59u, which has copper braid + aluminum foil shields, and is designed for a characteristic impedance of 75 ohms.  The RCA connectors on these cables are pretty chunky, fit tightly and have a split center pin, which makes the center pin fit a bit more tightly.  I measured them on my RF impedance bridge and they measure 75.0 ohms with very low SWR up to about 100 MHz.   They don't cost much, either- 3 ft pair under $7 including shipping.  They make about as good as an RCA SPDIF cable as you can get, in terms of their electrical and mechanical performance. You can buy much more costly cables for your RCA SPDIF use, but I am not sure it could be demonstrated that they would be better.
 
ACSS - well I was prepared to stop talking about this, as it appears there will never be a Stax-compatible amplifier that has an ACSS input, but someone asked what ACSS is so here is the answer: Years back, Krell developed a signal-transmission scheme called CAST, which Audio-Gd also uses and calls ACSS. This signal uses CURRENT instead of voltage to carry the signal, and as such it is immune to degradation of the signal by cables. (Has to do with the nature of source, amp and cable impedance in a current-based system, it just doesn't suffer the same problems that cables carrying voltage-based signals can.)  So, the theoretical advantage is that you can connect a source to an amplifier without ANY kind of noise, high frequency loss, etc that can come from cables.
 
If you read reviews of various Audio-Gd and Krell products that use these connections, they all report that the sound is better using CAST / ACSS  vs. balanced audio connects or single-ended circuits. Based on these opinions I began to wonder if  this technology, which is reported to offer sonic improvements audible on speakers and dynamic headphones, wouldn't also be a nice way to connect a source to a high-end Stax amp.  I mean, people are paying $1000 for an Alps RK50 pot to use as the volume control in their DIY-SRM-T2 "ultimate" Stax amps.... and I figured if they are going the 'cost-no-object" route, spending money on ANYTHING that will increase the sound quality EVEN A LITTLE for their Stax 'phones, I figured this technology ought to be tried, too.

 

[livewire]

Lately they have been paying around $600 for their RK50's.
Me thinks that is too much. $180 for a quad DACT is more than enough.
Of course I believe in BJ cables too, so wadoo I know?
 
Next up, NASA interconnects....

 

[ujamerstand]

^^ That RK50 costs even more after shipping and customs... Seriously man, should've went with a NOS quad of XF2 instead.

 

[Lil' Knight]

^^ That RK50 costs even more after shipping and customs... Seriously man, should've went with a NOS quad of XF2 instead.

lol... buyer's remorse

 

[ujamerstand]

Heh. You don't say. But even more reasons to get a quad of XF2 in the future. 

 

[Horio]

You need to move to the other side of the border ujamerstand.  Here we don't pay customs on hardly anything, nor tax on most everything ordered online... =P
 
The RK50 is a pretty spendy little pot.  I took the plunge because it solders directly to the board, and because if I ever wanted to try one the T2 was the build to do it!

 

[purk]

Quote:

Lately they have been paying around $600 for their RK50's.
Me thinks that is too much. $180 for a quad DACT is more than enough.
Of course I believe in BJ cables too, so wadoo I know?
 
Next up, NASA interconnects....

 
I can't find the vendor who sells the RK50 at that price any more.  Linky please?
 
 

 

[Horio]

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