Mr Pastern... get the soldering iron out

[DavidU]

A nice 811A single A

[dpastern]

I couldn't solder to save my life...I have all the electrician ability of a dead snail lol!

Dave

[DavidU]

:lol:

[erick]

Now where do I get 100V AC?

Aren't they lovely looking circuits. All nice discrete stuff! Umm Errr? What's it do?

[mswhin63]

Look like a single channel (mono) PA Amplifier. Uses a 100V speaker line. My valve theory though is very very very minimal as I did my apprenticeship just after valve technology was looking old.

[mswhin63]

Oops, only a standard speaker amplifier not PA. Doesn't look like it has a 100V speaker line connection.

[MrB]

Guitar amp.

[mswhin63]

Would deliver great sound being valve.

[erick]

Where is speaker connected - is that the 4, 8, 16, 18 ohm points to the right?

[MrB]

Yup ;)

[DavidU]

It's a mono power amp for stereo use using a 811A power triode (whopping big thing).Dave P likes these tubes.

[dpastern]

heheeh yes I do. 811 triodes were nicknamed "milk bottles". You don't want to screw up with them, the output voltages will kill. They're usually found in high end valve amps, usually single ended, quite often with 300b valves driving them. One of the most famous amps, Ongaku uses 811s from memory...

I'm a bit of a hi fi afficionado...

Dave

[erick]

I think I'm in love...................

http://www.idealinnovations.biz/images/classic/1088/1088_0108.jpg

[stephenb]

Thinking back, the number of valve televisions and radios I used to scrap in the 1980's was bordering on criminal. They were masterpieces but many were uneconomical to repair (from the point of view of the owners), and many of them never returned to collect them from our workshop. We literally ended up collecting hundreds of them.

I know they would be obsolete wuith current digital broadcasting, but when I got one repaired and glowing, I would stare at them for what seems like hours.

So sad valve technology is almost extinct, except for the niche markets, such as guiter amps.

[Ian Robinson]

Breadboards and pinboards are great .... no soldering required.

I've not done a huge amount of soldering (electronic varierty that is) and my soldering on circuitboards is pretty ordinary and rough .... good soldering comes with heaps of practice , I need more of that.

So what is the function of the circuit shown ?

[Ian Robinson]

Easy , buy a universial AC power adapter , they are cheap as chips.

Or use a stepdown transformer ie http://www.surplustraders.net/a/0709.shtml

[mswhin63]

One of my suppliers carries a valve headphone amplifer with electrostatic headphones cost $32,000 RRP.

Valve are so high in quality and low in noise unfortunately take up so much room.

[dpastern]

That wouldn't be an Orpheus (made by Sennheiser) by any chance Malcolm?

Dave

[mswhin63]

Yep, right, I haven't looked into these for a while as they are way out of the financial range of my clients.

[dpastern]

By all accounts it's a superb headphone unit (and utterly gorgeous). If I was filthy rich, I'd probably justify buying one. Until then, I'll stick to my 20 year old Sennheiser HD540 II gold references (limited numbers).

Dave

[DavidU]

True, this is what I do.

[dpastern]

Thermionic valves have a lot going for them as a rule - if the amp is built right and has even harmonic distortions, it's generally a bit warmish, but smooth, mellow, without any of the harshness or sharpness that plagues all but the best designed transistor amps (example, Krells, Mark Levinson, mostly running in pure class A mode). Cheaper valve amps seem to have odd hd and are sharper, more like transistors in some respects. Some say valve amps have a chubby bottom end (bass) and a overly warm and rounded top end - none of the valve amps that I've heard have ever exhibited this. The best sounding amps I've heard have all been valve. The nearest thing to it was a pair of Mark Levinson No 31 monobloc amps. mmm yummy.

Old isn't necessarily bad. People quite often make that mistake.

Dave

[DavidU]

The making of valves in Sydney
http://www.retrovox.com.au/amv1052.html

[GrahamL]

Thanks Dave that interesting stuff , I'll show my son whos made a couple of amps.

[Starkler]

Reminds me of when I was a kid scavenging parts from discarded tv sets and building valve radios. They always sounded better than any transistor radio of the day.