The Stax thread (New)

[spritzer]

It can be something as easy as a bad connection that causes the channel imbalance so Deoxit is your friend. Just don't get any of it on the diaphragm as the carbon coating could be damaged.

Originally Posted by ericj

Can anyone here confirm or disconfirm that the 1N6295C aka 1.5KE100C currently available from Littlefuse, Fagor, etc, are a reasonable equivalent of the long-discontinued Z1100 part in the MkII schematic? (or in the case of the original schematic, 1N6293C aka 1.5KE82C for Z1082).

The Z1100 is really just two 100v zener's back to back so why not just use those instead?

[ericj]

Originally Posted by spritzer

The Z1100 is really just two 100v zener's back to back so why not just use those instead?

I can't seem to find a 100v zener with specs that look like the Z1100. Doesn't help that transient voltage suppressors - which are just two zeners back to back - are specified with different terminology than zeners.

The part numbers i suggested are transient suppressors with specs very very close to the Z1100. Precisely the same if you look at the Fagor datasheet - but i can't find anyone carrying their part. The Littlefuse parts are a couple volts different, but available pretty much everywhere.

I'm more wondering if anyone's been down this same road before, perhaps used one.

[spritzer]

I built a version of this circuit back when it was retraced but used 81v zeners back to back (all I had at hand) but I can't remember if I ever fired it up. Using two zeners should have the same results since that's what Stax did on the older normal bias supplies and Beyer did on the N-1000 but it should be tested and compared.

[marcus1]

I have a SRM-1/MK Ⅱamp and trying to decide between the SR-303 or the SR-404.
I remember reading a while ago that, although more expensive, the SR-404 would be favored over the 303 because the cable is so much better - would this be the current thinking?
Or would one model be better suited (for my amp) than the other?

thanks

[The Monkey]

Originally Posted by marcus1

I have a SRM-1/MK Ⅱamp and trying to decide between the SR-303 or the SR-404.
I remember reading a while ago that, although more expensive, the SR-404 would be favored over the 303 because the cable is so much better - would this be the current thinking?
Or would one model be better suited (for my amp) than the other?

thanks

Get thee an older pair of Lambda Pros--or even better, a pair of Lambda Sigs.

[edstrelow]

Originally Posted by spritzer

Ditto. I'm using one now and it will tide me over until I get the BHSE or finish my own BH.

Voltage swing is only a part of the equation. You need current when the impedance drops and that's where the 717 comes out on top. Just look at how much power they draw from the wall and where all of it is going. The Stax tube amps were also never designed to drive the kind of load that a SR-007 presents and simply doubling up in the output stage on the 007t isn't going to transform the basic T1 design. Add that to the 6CG7's being fundamentally the wrong tube for the job and we prefer the 717...

Goodness, Spritzer is now using a transistor amp!!!!!!!

[ericj]

Originally Posted by spritzer

I built a version of this circuit back when it was retraced but used 81v zeners back to back (all I had at hand) but I can't remember if I ever fired it up. Using two zeners should have the same results since that's what Stax did on the older normal bias supplies and Beyer did on the N-1000 but it should be tested and compared.

Yeah, I've seen a schematic that uses an 82v device, i forget which one. probably the old srd-7. The srd-7 mkII schematic you posted a few days ago uses the 100v part.

i can't pull up a datasheet for the diode they say they used in the voltage multiplier, but I'm guessing i can use 1n4007 with no problem.

I guess next i should figure out an equivalent for that varistor. Or whether to leave it out.

[bralk]

Originally Posted by edstrelow

Goodness, Spritzer is now using a transistor amp!!!!!!!

"I don't have to use tubes in my designs; I only do it for marketing reasons. I've got an exact equivalent in solid state. I can make either type do the same job, and I have no preference. People can't pick which is which. And electrons have no memory of where they've been! The end result is what counts."

Tim de Paravichini (E.A.R)

Cheers

Tom

[twestby]

Originally Posted by bralk

"I don't have to use tubes in my designs; I only do it for marketing reasons. I've got an exact equivalent in solid state. I can make either type do the same job, and I have no preference. People can't pick which is which. And electrons have no memory of where they've been! The end result is what counts."

Tim de Paravichini (E.A.R)

Cheers

Tom

Now there's a guy in firm denial of quantum mechanics.

-Schrodinger's Cat, Jr.

[Hirsch]

Originally Posted by bralk

"I don't have to use tubes in my designs; I only do it for marketing reasons. I've got an exact equivalent in solid state. I can make either type do the same job, and I have no preference. People can't pick which is which. And electrons have no memory of where they've been! The end result is what counts."

Tim de Paravichini (E.A.R)

Heh. At the 2006 Rocky Mountain Audio Fest, one of the displays was a blind test of a transistor vs. a tube amp. Most of the votes appeared random, but I was able to tell the exhibitor exactly which one was the tube amp, and why. Of the 200 or so people that they had tested by that point, I was apparently only the fifth person to make a clean identification. So, TdP may have it partly right, in that a lot of people really can't pick which is which. But those of us who can are rather emphatic about which we like.

[spritzer]

Originally Posted by edstrelow

Goodness, Spritzer is now using a transistor amp!!!!!!!

I've always used a SS amp in my computer rig except when I'm testing some gear so no need to panic...

Originally Posted by ericj

Yeah, I've seen a schematic that uses an 82v device, i forget which one. probably the old srd-7. The srd-7 mkII schematic you posted a few days ago uses the 100v part.

i can't pull up a datasheet for the diode they say they used in the voltage multiplier, but I'm guessing i can use 1n4007 with no problem.

I guess next i should figure out an equivalent for that varistor. Or whether to leave it out.

I've used 1n4007's with no problems in the past and I would just leave the varistor out. Most of this stuff was put in to make the thing idiot proof after a lot of arced phones in the past.

[Johnny Blue]

My SRD-7 looks so simple inside (relatively speaking) I can't believe it's a lifetime's project to up one of the sockets to Pro bias (especially as it's one of the older, mains-powered variants): I just need someone to tell me what to solder where!

[ericj]

Originally Posted by Johnny Blue

My SRD-7 looks so simple inside (relatively speaking) I can't believe it's a lifetime's project to up one of the sockets to Pro bias (especially as it's one of the older, mains-powered variants): I just need someone to tell me what to solder where!

It's not a lifetime's project.

But high voltage circuits are not to be trifled with.

Outside of the SRD-7, it's voltages cannot hurt you (unless you really work at it) because the resistor on the output of the bias circuit prevents much current from leaving it. If you put a load across it, the bulk of the voltage drops across the resistor.

Inside of the SRD-7 are voltages that can easily kill you if you don't show them proper respect. It is not the place to start learning about basic electrics.

[Johnny Blue]

That's useful to know! But surely if the SRD-7 is left unplugged for an hour or two, any potentially lethal charges will have dissipated (and I don't recall any big capacitors in there in any case), so it should then be safe to work on? Or am I in way over my head here?

[2deadeyes]

Just completed the blutack port mod for MK2 - can't believe how plugging 2 ports can change the sound that drastically. The sound is now definitely close to MK1. I noticed that the bass has even more slam if I decreased the pressure from headbands. I guess with more pressure from the headbands, there's less room for the diaphragm to move with more pressure. MK1 is still more neutral relative to the MK2, which I prefer.