Valve experiences (1976 to 1987) The golden years? Err no, not necessarily!

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Originally Posted by Marco

I've never tried any of those so can't comment, but I'm sure you're right.

However, I wouldn't make sweeping statements about Chinese valve amps being "crap", as if they all were, as just as many examples (or more) can be given of very good ones other people and I have used :)

I could go on about, for example, the crap valve amps from Unison Research, Graaf, Audio Research, McIntosh, Conrad Johnson, amongst others, I've heard over the years from these so called respected 'hi-end' manufacturers and some of the rip off prices being charged for no more than mediocre sound quality! ;)

It's just like anything else in hi-fi, there are good and bad examples of everything. However, in my experience the Chinese get right far more than they do wrong - and they learn quickly from their mistakes.

Marco.

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I'm not saying that all Chinese equipment is C**P i'm sure there must be one or two out there that are good. Shanling and Opera Cons come to mind, I believe they have a reasonable reputation. However I think if you were to take a straw poll on many of the forums you would find lots of people who have bad experiences with Chinese equipment. Most likey this would outweigh those who have extoled the virtues of their Chinese amps.
I for one am prerared to forgo some of the performace and pay more in favour of something that
**can be easily reparied
**is spported by the manufacturer
**uses quality components
**is reliable and dependable
**dose not have to be modified to cure inherent problems such as hum
**or be made safe to use

If members have really good experiences with their Chinese equipment spread over a reasonable period, not just a few months then it would be good to know. There are however manufacturers out there who have a 30 years plus of manufacturing and supporting valve amps who might be a better bet in the long run?
I.E.
ARC
Manley Labs
Atama Sphere
EAR Yoshino
Audio Valve
Croft
To name but a few.
At least these Guys dont pass off Chinese made equipment as their own which seems to be a growing trend in the market.

Those are all valid points, but the reality is there are far more than just "one or two" Chinese valve amps that are good. Amongst the commercial designs you could also add Primaluna and Puresound to your list, and there are plenty more. If you decide to buy direct from China you just need to do your research properly and adopt some common sense.

Or you could simply have a reputable and experienced valve engineer (such as our own Nick or Anthony) design something bespoke for you which would fulfil all your above criteria and likely outperform most commercial designs at a fraction of the price, and would also be supported by them, too :)

In my opinion Croft are different because Glenn is basically like Nick or Anthony but just happens to be somewhat more well-known. The prices he charges are also 'real world'. World Designs equipment (ready assembled or in kit form) also offers superb sound-per-pound value combined with a professional and reliable back-up service.

These days, as far as valve amps go, there is simply no need to pay for a desirable audiophile 'badge', providing sound quality is your primary concern.

Marco.

I would put a vote in for Mr Liang. I've an 845 SE which while was very good indeed out of the box,has become superb with some very simple tweaks. I run it straight off UK mains and it's given totally trouble-free service for I think around 18 months now.

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Originally Posted by jandl100

They are made by a small specialist form in Hong Kong called "Musician". The amp is simply called "Tube Amplifier" !!

They are very nicely made - I bought them on eBay and and once the seller had the power supply rebuilt to banish hum problems, they have sounded simply fabulous - superb with my Quad 57s and my old ProAc Future Point 5s. But being OTLs they don't like low impedance loads, though - with my old Thiel CS2.3 (a notoriously difficult 4 ohm load) they topped out at anything above moderate sound levels.

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Had a look on the web to see if i can find some more details but drawn a blank. Do you have a URL or any contact details?

I see you use active speakers now so are they now unused?

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Originally Posted by Complin

Had a look on the web to see if i can find some more details but drawn a blank. Do you have a URL or any contact details?

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Nope, they are a complete mystery to me, too!

Here's a photo of the front fascia which presents all the info I know about them! ...

http://i262.photobucket.com/albums/i...Lampfascia.jpg

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Originally Posted by Complin

I see you use active speakers now so are they now unused?

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Yep, they are sitting alone, forlorn and unused at the moment. :( Most sad.
I must admit that I am reluctant to part with them as they are, imho, the best power amps I have ever heard (and I've heard quite a few in my time ;)). I'm bound to get some more passive speakers that are a fairly easy load sometime and I bet I would regret selling the OTLs when that happens! :doh: (In fact, I've got my eye on an eBay auction at the moment!)
But, of course, for the right offer .... ;)

It is sometimes said that with OTL amps there's a danger that a failing valve will damage the speakers - do you know if that's true ?

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Originally Posted by Togil

It is sometimes said that with OTL amps there's a danger that a failing valve will damage the speakers - do you know if that's true ?

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This is what Wikipedia says about this
Output transformerless amplifiers (OTL)
The output transformer (OPT) is a major component in all mainstream valve power amplifiers, and in addition to having a high cost (at least for a good one) they remain engineering compromises that deviate significantly from the idealized form.

One approach to avoid the problems of OPTs is to avoid the OPT entirely, and direct couple the gain device to the output (as is done with most transistor amplifiers for example). Some designs without output transformers (OTLs) were produced by Julius Futterman in the 1960s and '70s, and more recently in different embodiments by others, in an attempt to overcome the problems of transformers.

To do this one must deal with the characteristics of the valve, low current capability for a given anode voltage; consequently very particular valves must be employed. If done with care and the correct configuration, reasonable efficiency and moderate Zout (damping factor) can be achieved.

These effects mean that OTLs have selective speaker load requirements, just like any other amplifier. Generally a speaker of at least 8 ohms is required, although larger OTLs are often quite comfortable with 4 ohm loads. Electrostatic speakers (often considered difficult to drive) often work especially well with OTLs.

The more recent and more successful OTL circuits employ an output circuit generally known as a Circlotron. The Circlotron has about one-half the output impedance of the Futterman-style (totem-pole) circuits; far more important is the fact that the Circlotron is fully symmetrical and does not require large amounts of feedback to reduce output impedance and distortion. The result overcomes the biggest hurdle suffered by the prior art: stability. Thus modern OTLs can be as stable as any amplifier made. Successful embodiments use the 6AS7G and the Russian 6C33-CB power triodes.

A common myth is that a failure (short) in one of the output valves may result in the loudspeaker being connected directly across the power supply, and thus being destroyed (possibly quite spectacularly). In practice, the older Futterman-style amplifiers have been known to damage speakers, not out of shorts but out of oscillation. The Circlotron amplifiers often feature direct-coupled outputs, but proper engineering (with a few well-placed fuses) ensures that damage to a speaker is entirely within the same realm as conventional amplifiers. Certainly it is nearly impossible for the speaker to wind up being across the power supply!

OTLs have been a growing niche, as the Circlotron is so successful that modern OTLs are often more reliable, better performing, better sounding and less expensive than many transformer-coupled approaches. In recent years, the popularity of single-ended triode amplifiers has dramatically increased the range of loudspeakers suitable for OTLs.

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Originally Posted by jandl100

Nope, they are a complete mystery to me, too!

Here's a photo of the front fascia which presents all the info I know about them! ...

http://i262.photobucket.com/albums/i...Lampfascia.jpg



Yep, they are sitting alone, forlorn and unused at the moment. :( Most sad.
I must admit that I am reluctant to part with them as they are, imho, the best power amps I have ever heard (and I've heard quite a few in my time ;)). I'm bound to get some more passive speakers that are a fairly easy load sometime and I bet I would regret selling the OTLs when that happens! :doh: (In fact, I've got my eye on an eBay auction at the moment!)
But, of course, for the right offer .... ;)

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Thanks i'll have to keep an eye out on flea bay

Hope the pair of speakers you have your eye on are not the same one's i'm bidding on!

Have you ever tried one of the Radfords STA 15 or 25, they are supposed to have a particular synergy withe Quad ESL's? The Bewitch amps also seem to have some good press and I think are sold under a couple of names in the UK.

There are a few weasle words there:

"A common myth"

And then

"Certainly it is nearly impossible for the speaker to wind up being across the power supply"

Last time I looked nearly impossible wasnt the same as never possible, and if something is occasionaly possible, then it can happen, so is hardly a myth.

It does make a valid point though, many DC coupled SS amps are just as capable of connecting the loudspeaker to the power rails. The unmentioned problem though, is a OTL pushes valves where they are not intended to be, even freak valves like the 6c33c are pushed to the edge, and in that case failure modes can tend to be not of the "gently fade away" form.

They can sound very good though, very speaker dependent, but in the right conditions rather good.

BR makes some nice kits:

http://www.transcendentsound.com/T16OTL.htm

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Originally Posted by lurcher

There are a few weasle words there:

"A common myth"

And then

"Certainly it is nearly impossible for the speaker to wind up being across the power supply"

Last time I looked nearly impossible wasnt the same as never possible, and if something is occasionaly possible, then it can happen, so is hardly a myth.

It does make a valid point though, many DC coupled SS amps are just as capable of connecting the loudspeaker to the power rails. The unmentioned problem though, is a OTL pushes valves where they are not intended to be, even freak valves like the 6c33c are pushed to the edge, and in that case failure modes can tend to be not of the "gently fade away" form.

They can sound very good though, very speaker dependent, but in the right conditions rather good.

BR makes some nice kits:

http://www.transcendentsound.com/T16OTL.htm

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Perhaps this is why you never see designers like Tim De Paravacini use OTL in their designs. Only Enhaced Triode or conventional push pull.