The Stax thread - Page 148  

I'm definitely keen but it's more than I can spare for a few weeks. Just bought a new laptop and I've got a PS3 preorder to pay for.

A fun search smeggy. I'm looking forward to powering my SR-X/SRD7 from my Pass Aleph 3, which has been out of my main speaker rig for a couple years now - I just couldn't bear to part with it.

Patrick

Nice, the Aleph 3 should do outstandingly with the SR-X from what I've read. I'd love one myself. Sadly I'm going to have plenty of time to consider as it'll take just short of forever to save up for an amp. I'm hoping that by the time I'm ready some of the RWA Sig 30s will be up for sale at nice prices

Sorry to interrupt, but could someone please advise me on upgrading the tubes inside my SRM-006tMk1? They're 6FQ7/6CG7 (same tube, two names?). Will NOS tubes like these ones work 1, 2 ? It's odd I'm even considering this because I told myself I'd never ever tube roll... Where do I start? There are so many different types of 6SN7 tubes

They are not 6SN7s; they are 6CG7s. The best 6CG7/6FQ7s I've heard are RCA Cleartops.

Thanks. I had no idea why I started going on about 6SN7S So these are the Cleartops? (http://cgi.ebay.co.uk/Matched-Pair-R...QQcmdZViewItem) They don't look too clear to me... Where will I be able to get a pair of RCA cleartops?

EDIT: nvmd, found it here: http://www.thetubestore.com/rca6cg7.html 35USD + shipping. Sounds reasonable to me!

EDIT2: found another site here: http://www.tubedepot.com/nos-6cg7-rca.html They offer "matched + balanced triodes" and "Low noise/microphonics" as options but can't be configured to have both?!

http://www.tubedepot.com/nos-6cg7-rca.html

These are cheaper.

For the 006t, try a pair of these:

http://cgi.ebay.com/NEW-6FQ7-6CG7-RA...QQcmdZViewItem

In reading through the STAX archives, I found this old but oh so true statement by (wise beyond his years) Meyvn. It works wonders for me and helps put things in perspective from time to time. Just thought that I would re-share is all.

I agree, these are the best tubes I've heard in the SRM-T1. It's not that hard to roll tubes but they can be a pain to bias correctly.

Thanks Hirsch, spritzer and humanflyz. I just got a pair of the Raytheon 6FQ7/6CG7 from the eBay link because they're much cheaper than the RCA Clear-tops. I'll consider getting a pair of them at a later stage.

Regarding biasing... I just read the bit in Adhoc's Tube FAQ for Newbies and I'm guessing the 006t is not autobiasing? I still don't get how you bias an amp

The amp isn't auto biasing but it isn't very hard to do. All you need is a multimeter and a flat screwdriver, preferably plastic or electrician set that has just the metal tip exposed. The instructions below are easy to follow but instead of the colored wires use the following picture.

You put the probes on + and - and adjust TVR1 (a little plastic trimpot on the pcb) and then you put one of the probes on either + or - and the other on the groundpost on the back of the amp and adjust TVR2. You are of course adjusting DC voltage for it to be as near zero as is possible.

SRM1/MkII Query

I wrote earlier with a number of questions about Stax gear (p. 102): thanks for your answers, spritzer:
Does this mean yes (it is OK to use the 5 pin SRE-15N for the 6 pin SRXs)?

As I wrote, I have found that my SRX Mk IIIs start to make odd sounds when connected to the Normal bias outlet of the SRM1/MkII (popping diapraghm noises?) and of course I have stopped trying them this way in case I am doing damage to the SRXs.

However, I tried today running some Pro earspeakers (202s) out of the Normal socket and discovered that they sound absolutely identical (volume, etc.) as through the Pro socket. I had expected the sound to be softer, quieter, less dynamic -- as reported on these pages -- but I can hear no difference at all with the Normal bias outlet. So now it occurs to me: could the SRM1/MkII have been modified to provide 2 Pro outlets, and, if I looked inside, what would I see if they had?

(If this is the case, this would, of course, presumably explain the odd sounds from the SRXs when they're driven from the Normal outlet of the SRM1/MkII: they are being given too high a bias voltage... )

It could very well be the case and it is easy to check. If you open up the amp and use the picture I posted above you can find the bias pin. There should be two separate wires coming from two separate places on the main board in the power supply section. In the picture below the wire for the normal bias is blue and I can't quite see the pro bias wire but it should be gray.


I have once plugged my SR-X into a pro socket and they were very loud... very very loud.

Thanks spritzer, I can't see your picture, but I've opened my SRM1/MkII and am astonished to see that the Normal socket is just the Pro socket duplicated exactly! What's weird is that the wiring seems to be original (same colour and type of wire, no evidence of re-soldering... ), so it looks as if Stax were shipping SRM1/MkIIs (mine's a C series, #5562, as discussed and pictured earlier on this thread) WITHOUT real Normal bias sockets!? What's going on?

By the way, I'm wondering what damage I'll have done to my SRXs with the higher bias voltage (I only ran them for a few minutes this way, before I began to notice the odd sounds, about which I've written).