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Play time ahead.....


maxg

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Just back from Tsakiridis for tubes. I only needed one EH EL34 - which he gave me FOC because the last set I got from him was less than a year ago and he reckoned it should have lasted longer (what a nice guy).

So I bought 4 more - just to cover for future mishaps - and he showed me how to bias my amps - which seems quite easy (so I will be able to get a picture of the interior for you all - finally).

Then I saw a couple of quads of Svetlana 6550C tubes on another version of my amp he had there - so I bought those as well.

Armed with, therefore, a armful of tubes I set off and picked up a cheap digital multi-meter to try out the biasing tonight.

According to Odyseus (Mr Tsakiridis - actually soon to be Dr - he is doing his PhD in Electronics of one form or another) I should aim for 150-200 mV for the EL34's and 200-250 mV for the 6550's.

Lots of play ahead.

A few other interesting items arising:

1. He is looking to expand - so if any of you know a company keen to get into the tube line with a bunch of ready made designs to cover the US - please let me know.

2. He is looking at digital amps - something good could be coming soon.

3. He has promised me to keep his internet site more up to date. This should mean a page dedicated to some of the one off designs he has done for customers - that are most impressive....

that's it currently - now I am off to see if I can figure out how this multi-meter works...

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These are the only EL34's I have ever used so I cant help you much. They came with the amp and when I asked on this forum everyone seemed to think they were the next best thing to NOS.

I got them at $15 a piece - which is very reasonable over here - not including the free one of course.

The 6550's were more expensive - at $300 for a set of 8 - ah well - easy come - easy go I say - just got to hide the deal from the wife!!!

This multi-meter is mystifying - DC-volts, AC-volts, resistance, AC-amps, DC-amps and 2 things I dont understand - one looks like an arrow over-running (diode measurement apparently - just read the manual) a plus sign and the other is hFE - transistor measurement for NPN or PNP type transistors - huh???

Ah well - I think I have the DC voltage sussed and that is the bit I need...

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Max,

Craig had to walk me through, over the phone, the first 2 times I biased my scott and the first time I biased the MKIIIs. You're not alone.

I wish I could help. Send Craig an email and I'm sure he'd lend you a hand. Unfortunately, it would be an expensive call for you but he could probably help from the keyboard.

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Craig,

Thanks for the offer but actually I am quite confident as I have already done one!!!!

Odyseus has a clever system. He put the identical unit in front of me in his workshop - stuck some tubes in and made me bias it!! Worked a charm - I could do it in a dark room with my eyes shut (well - almost...)

All I needed was the figures to aim for, a meter and instructions about where to stick the needles (dont go there). It was actually quite easy - but a pain in the butt for 8 tubes...

100 wpc here I come!!!!

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