[Dinan]

I have a 717 and up until now I have used only the RCA or XLR inputs independently of each other. This morning I hooked up both a single ended AND balanced source at the same time and attempted to use the RCA/XLR selector switch to select between the two inputs. The inputs cross over each other and the presence of a balanced input screws up the RCA input regardless of where the selector switch is. If you have an XLR input (but no RCA connected) and the source selector is over to RCA, you drop about half the volume level so it is like one leg of the balanced feed is disconnected but not both. It is very odd. I took a look in there and it doesn't look like someone rewired the unit.

Is the rear selector not a TRUE input selector to toggle between two inputs?

I thought I would check with those in the know before I start trying to diagnose a defective switch or wiring issue if there really isn't one.

I don't have a manual or a quick look would probably tell me what I need to know.

TIA!

 

[spritzer]

Very bad idea to do this as the 717 has no input switch. The switch only grounds the - side of the amp when using an SE input.

 

[Cool_Torpedo]

I didn't know that. I might have plugged in different DACs, one into the XLR and the other in the SE input...

 

[Dinan]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif Very bad idea to do this as the 717 has no input switch. The switch only grounds the - side of the amp when using an SE input.

Well that answers my question as I do not have a manual and explains everything.

Now why in the world would they have a grounding selector switch?! I am going to have to pull it apart and see what they are trying to do in that circuit.

 

[spritzer]

That's how you are supposed to setup a truly balanced amp. On speaker amps you often have to install metal jumpers in the XLR sockets when using SE, this is the same thing.

 

[Dinan]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif That's how you are supposed to setup a truly balanced amp. On speaker amps you often have to install metal jumpers in the XLR sockets when using SE, this is the same thing.

Okay, now I understand what they are trying to do. They have jumped the RCA to 2 pins of the XLR and the switch bridges the 3rd pin over. That is a novel way of doing things.

I am going to rewire the unit, get rid of the internal volume control bypass switch (or replace it with a high-end unit?, put better XLR & RCA connectors in, and try to put a proper input selector switch in if there is room.

I like a good project!

Too bad I don't have the time to build a T2 as that would be fun.

 

[spritzer]

I would personally put in some work on the PSU but a better volume control wouldn't hurt. Not many options for you that will fit in the chassis though. Probably just some of the TKD 4CP units if you can find one.

 

[wavoman]

Quote:

Originally Posted by Dinan /img/forum/go_quote.gif If you have an XLR input (but no RCA connected) and the source selector is over to RCA, you drop about half the volume level

Yep. Last weekend I spent 4 hours tracing every piece of wiring in my convoluted set-up trying to find why I lost all my vol in the 717. Never noticed that the stupid switch got pushed over to the RCA side when I moved the amp.

Only after I disconnected everything and started to open it up did I see the problem! I used the Gore Protocol (black electrical tape on the switch) to prevent this from happening again.

 

[gilency]

"There are two pairs of RCA jacks and one pair of XLRs on the rear panel. (Pin 2 of the XLRs is negative, following the usual Japanese practice.) The inputs are paralleled; you can use single-ended or balanced connections, but not both. A Bypass mode on the 717 allows its volume to be controlled by an outside source, presumably a preamp, passive volume controller, or an integrated amp or receiver with "preamp out" facilities."
Stereophile: Stax SR-007 Omega II electrostatic headphones

 

[Dinan]

Quote:

Originally Posted by gilency /img/forum/go_quote.gif Stereophile: Stax SR-007 Omega II electrostatic headphones

Thanks for the review link...I enjoyed reading it. Also good insight as to how STAX wires the inputs on their amps.

 

[edstrelow]

The old review also lsts the price for an Omega2 and stax amp as being in the $7,000.00 range. I had forgotten how costly these were initially. Some years later I got mine direct from Japan for about $3,000.00.

 

[Dinan]

Quote:

Originally Posted by edstrelow /img/forum/go_quote.gif The old review also lsts the price for an Omega2 and stax amp as being in the $7,000.00 range. I had forgotten how costly these were initially. Some years later I got mine direct from Japan for about $3,000.00.

No kidding, the pricing was BRUTAL!

 

[spritzer]

Quote:

Originally Posted by edstrelow /img/forum/go_quote.gif The old review also lsts the price for an Omega2 and stax amp as being in the $7,000.00 range. I had forgotten how costly these were initially. Some years later I got mine direct from Japan for about $3,000.00.

With the release of the SR-007A saw the first price increase of an Omega headphone since 1993 by about 15000Yen. The MSRP had always been 180,000Yen until then.

 

[gilency]

Waiting for Christmas to get me an SR-007 MK1. If anybody plans on selling one by December please keep me in mind.

 

[Dinan]

Quote:

Originally Posted by spritzer /img/forum/go_quote.gif With the release of the SR-007A saw the first price increase of an Omega headphone since 1993 by about 15000Yen. The MSRP had always been 180,000Yen until then.

Yes but US pricing has been ALL over the place due to differing exchange rates and importers.