spritzer

The SR-80 Pro shipped with a bog standard SRD-4 except it had gold printing on it. Well that and the SRM-Xs too which was just a Xh minus the bias supply. There is no difference between the boxes whether they have bias or not. The SRD-6 not having protection resistors almost guarantees that it has suffered some damage. The SRD-6's also didn't have a power switch which has caused some problems though mostly on the headphone side.

The current draw of the EL34 is 1.6A but it's +/-10% so a minimum of 4A is what I'd use.

Some of them have shield in the barrel but I'm not certain that all of them have it. 5 pin would be better but thinner conductors means less bass molecules so nobody would do that.

The thermistors can go bad and do all sort of funny things to the amps. Try bending the arc to get a better fit on the SR-40. Most of these were designed to be bent into shape.

Yeah, my point exactly. 100kHz or less... not so much.

So many design variations of the SRD boxes to know what they did in any one of them but the SRD-6 could have been overloaded at some point and thus some parts were damaged. Stax never built any EQ into these.

I agree, the PSU either works or it doesn't.

Yeah, I'd love to hear about the influence of right angle traces at these frequencies. Seems a bit like Ray saying you need thicker wire for the bass molecules to get through...

Those are actually leftovers which we take each week and form into a dough with some chocolate and rum. They are then covered in chocolate and coconut shavings. The ones directly below the balls are out oat and raisin cookies with the chocolate ones on the left. These have only Valrhona chocolate in them. Only the best... On the right which looks like a hat is a ball of marzipan with some pie dough underneath. On the bottom we have Berliner, i.e. jelly donuts and a mixture of macaroon paste with a butter-dough bottom.

...so what do you think of it?

Nope, DC isn't a problem for electrostatics.

Voltage doubler off the built in switcher.

It's been a while since I bought some but the RN65's are almost twice the length so yeah, creative lead bending would be needed. It's a 1W part though so utter overkill with so many 1/2W units available.

RN65 resistors won't work, they are huge. The RN numbering is milspec so a 1/8W resistors is actually 1/4W, 1/4W is actually 1/2W and so on. Here is the diode, use it: 511-STTH512FP This is the resistor you want: 71-RN60D1743F

Just try the 5A one. It should only blow the fuse if something is shorted on the board. I've seen all manner of KGSSHV psu failures but never a full short.

The fuse rating for torodial has very little to do with the actual current draw of the circuit. The inrush current is the problem that needs to be accounted for.

You're in the US? Then a 3.15A fuse might be on the small side of things. Try 4AT and see if it holds up.

That post shows a huge lack of knowledge of how the tube industry operated back in the "good old days". Manufacturing tolerances were crap to say the least and everything was done to keep costs down. There is also a huge difference between just about works and works comfortably. Let's also look at what was happening in the early 50's, that's when the improved novals are being phased in so they had to find some use for their obsolete octal tubes. A manufacturer "inventing" new ways to use an existing product when the market place shifts, perish the thought... that would never happen.

If you are using a TRS plug then I'd uprate those resistors massively. A lot of current will be flowing through them. Better yet, use a 4-pin XLR.

My problem with the 6SN7 comes from not finding any evidence that the tube was actually redesigned to fit those parameters. Sure they altered the filament a bit so you can series wire them in TV's but other than that they seem to be bone stock 6SN7's. Call me a cynic but it smells of "sure we can push to that" as we have millions of these tubes in stock. The ECC99 spec sheet is very lacking but it's a sort of a hybrid between the 6n6pi and the 12BH7A. No need for peak voltage in those as it's only applicable in TV use. It's a worthless measurement for our use.

Some are real, some might be Chinese copies. That is true, especially of the 2SC1815. Nothing wrong with using MPSA units though

If you are really bored as there are hundreds of revisions, some tiny but also some major ones.

The amp board is different. It's a bit smaller to suit my needs.

I've been keeping this circuit in the back of my mind and it could work to use ECL82's with it. That is a true 600V tube so triode strap it and use the built in triode for the second stage. I'm going to do something similar for a mini megatron to match what I did with the Octave.

I've never come across fake 2SC4686A's but I'm sure they will surface once supplies dry up. I bought thousands of them from Japan and I've been selling them with the boards.