Valve amp virgin, some advice please on valve choice?

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andrew Ivimey
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#31

Post by andrew Ivimey »

There's nothing wrong with being wrong. I remember the time well. It was a learning experience.
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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#32

Post by Ali Tait »

The seven funereals of work collegues I have attended over the years have taught me a deep respect and fear of electricity.
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#33

Post by Mike H »

pre65 wrote:
Neal wrote:
....Phil are you convinced yet!? :wink:
Yep. :oops:

I've been wrong before, and no doubt will be again. :)
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#34

Post by gazjam »

all this talk of voltages, burt carpets and electric shocks...
What have I let myself in for!

Going for THIS:
http://forum.audiogon.com/cgi-bin/frr.p ... -Tube-amp-

Been re-valved very recently...

Brand New GL KT88's..
Siemens ECC83's..
and a Pair of RCA 5814A which have a few hours on them.

My first proper valve amp, looks good?
Upgradable in the long term?
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Ali Tait
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#35

Post by Ali Tait »

One thing to look at is whether the mains trannie is 220 or 240v. If 220, the use of a variac or bucking transformer would be a good idea.

Check there is a proper chassis earth too.
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#36

Post by Neal »

More than a good idea Ali! :shock:
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Ali Tait
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#37

Post by Ali Tait »

Worth checking, my Liang was a well made amp with good trannies but didn't have a mains earth.
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andrew Ivimey
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#38

Post by andrew Ivimey »

um, it might be worth checking and didn't your Mr Liang amp have no earth Ali?!
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Nick
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#39

Post by Nick »

Looks neat enough inside, space to replace the coupling caps and pot. I would have hoped for more power supply electrolytic in there. A lot depends on whats inside those transformer cases. It would be nice to know more about the circuit before buying, but thats part of the reason they are cheap.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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andrew Ivimey
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#40

Post by andrew Ivimey »

um, sorta ruins my joke that
um, sorta ruins my joke that
um, sorta ruins my joke that

Okay it wasn't that good a joke ...

I've taken two chinese amps apart. The output transformer housings (pottings) on both gave the impression of hugeness. In one amp the outputs were pretty titchy. In the other the metal used for interleaves were very thick. IMO that interleaves should be thin as razors and there is a good and noble reason why this is so. Neither amp was very good. One was totally horrible but the mains transformers were very useful as were the phonos and speaker lugs.

I still have a KT88PP amp that sounds reasonable but I added an inrush limiter to the PSu to stop nasty sounds on switch off. The 829PP Chinese amp I have is the preamp for 833s. It works!
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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#41

Post by gazjam »

Thanks for the feedback.
The usual buyers remorse isn't kicking in, probably a good sign.

Its a 2nd hand buy thats been used by a couple of Hifi Wigwam veterans, so hopefully voltage in UK is ok!
Good to know theres some upgrade potential too.
The amp weigh's 30kg apparently, dont know if weight signifies anything of note?

No circuit board, is the Point to Point wiring in there a good thing?
Forgive the simple questions, still trying to learn:)

Ta.
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#42

Post by pre65 »

gazjam wrote: Its a 2nd hand buy thats been used by a couple of Hifi Wigwam veterans, so hopefully voltage in UK is ok!

Ta.
Don't assume that. :)

If it's made for 220v usage (which it probably is) then using it on 240-250v UK mains will make all the voltages high.
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Ali Tait
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#43

Post by Ali Tait »

Yes, the amp may work fine but it's lifetime be seriously shortened by the voltages being too high.
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pre65
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#44

Post by pre65 »

A good place to start is measuring the valve heater voltages as they are a well published figure.
The only thing necessary for the triumph of evil is for good men to do nothing.

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#45

Post by izzy wizzy »

On the high voltage thing. I read somewhere that once you go above 1000V, all of a sudden you don't need to touch it, it will find you. Much like it found the carpet I imagine ;-) That keeps me on my toes when going near my 813 PP amp. I certainly never poke a multimeter probe into it, even on the driver side when the HT is on. Big blue mercury glow, fingers stay out. I've been knocked off my feet with 600V, tingled by the 240 mains. Don't fancy being carbonised.

Anyway, even on 95dB speaks, I'm a PP man. Would love to get up to Owston one time. Sounds fun!

cheers,

Stephen
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