Valve Amplifier Kits

[Edward Huggins]

From time to time there are Posts for those who seek vintage valve amplifiers and plan to refurbish them. Even so, such classics as Quad, Leak, Radford et al, and needing repair, can still cost hundreds. Just think of the cost of new matching valves and TX rewinds? Even working, small, Tripletones can fetch over £300....

Given all of this, and the ability of most Members, there has been very little mention here of those apparently quite respectable Chinese amplifier kits that are held in stock in the UK (no prohibitive shipping) where for just over £200 one can buy an EL34 single-ended stereo amplifier and for a little more the PP version. All brand new of course.

Maybe I am being naive and there is a downside to these that I might be overlooking?

[GrimJosef]

Single-ended amps can be jolly little things (or jolly big things if you're brave enough to get into 'trawler triode' territory). I have a Mullard 3-3 which is suprisingly creditable. But they're not really hi-fi, the definition of which in the classic era came to be (roughly) 10-20W of audio power, 0.1% THD (maybe 0.2% if it was mostly 2nd harmonic), 20Hz-20kHz (maybe a bit narrower at full power), hum and noise 80dB below maximum output and an output impedance not much above 10% of the load impedance. The Quad, Leak, Radford and a few other push-pull designs will deliver that. Single-endeds won't.

As far as modern push-pull amps go, the quality of the output transformer makes a big difference. These used to be volume products and the impact of that on price was substantial. They aren't volume products any more so even with globalisation I wouldn't expect the transformers in a £200-300 stereo amp to be very good.

Cheers,

GJ

[Radio Wrangler]

As G-J says there were some very decent amplifiers which in their day were recognised as high fidelity, and the single-ended jobs of the era weren't. People were neither stupid nor cloth-eared back then. They listened to live performances and reproduced ones. They could tell what worked and could vote with their wallets. They made their own minds up.

Seen in this context, the fad for single ended amplifiers and the claims for them to be at the highest end of 'high end' are a little perplexing.

Something has certainly changed.

Single-ended amps and various other designs have acquired some sort of invisible fairy dust. Only specialist aficionados can tell if it's there. The rest of us are left mystified.

Put simply, whatever it is, the Chinese kits are considered by the aficionados to not have the fairy dust.

For those of us who can't detect the stuff, we can either sulk outside the door, mourning that we cannot see the path to enlightenment, or we can celebrate that our lack of such perception frees us to listen to and enjoy all sorts of things that the acolytes are compelled to eschew. Suits me fine!

It seems unfair on the people making quite decent kits. Even if they upped the quality of their output transformers, I fear they would still be considered non-U. The Americans have the concept of 'cooties'

David

[Ted Kendall]

Originally Posted by Radio Wrangler

Single-ended amps and various other designs have acquired some sort of invisible fairy dust. Only specialist aficionados can tell if it's there. The rest of us are left mystified.

Yup...

[trobbins]

Such kits have caught a few newbs out badly, as the kits can come with minimal or no instructions, and sometimes just in a foreign language, and with no technical support. Not an issue if you have the experience and test tools, but they can lead to some selling all the parts in some state of installation, and for that person to be frustrated and looking for another hobby to take on.

[bikerhifinut]

Originally Posted by GrimJosef

Single-ended amps can be jolly little things (or jolly big things if you're brave enough to get into 'trawler triode' territory). I have a Mullard 3-3 which is suprisingly creditable. But they're not really hi-fi, the definition of which in the classic era came to be (roughly) 10-20W of audio power, 0.1% THD (maybe 0.2% if it was mostly 2nd harmonic), 20Hz-20kHz (maybe a bit narrower at full power), hum and noise 80dB below maximum output and an output impedance not much above 10% of the load impedance. The Quad, Leak, Radford and a few other push-pull designs will deliver that. Single-endeds won't.

As far as modern push-pull amps go, the quality of the output transformer makes a big difference. These used to be volume products and the impact of that on price was substantial. They aren't volume products any more so even with globalisation I wouldn't expect the transformers in a £200-300 stereo amp to be very good.

I agree GJ.
It hasn't stopped me from the odd SE DIY build and they certainly have been jolly nice little things and very pleasant to listen to.
As to the more esoteric end of the Single ended market, I haven't properly heard something like a 2A3 or 300B amplifier and can't comment on how they sound to my ears. But I'm a bit dubious about these older directly heated valves in terms of hum and noise which for me would be a deal breaker. And they are excruciatingly expensive.
You can get a genuine 10Watts of very low distortion audio from a pair of push pull EL84 which are in my book the best value audio valve ever manufactured. The difference between something like a 3-3 and a leak Stereo20 is so much more than the extra valve and I still use my old stereo20 which was simply refurbed with modern metal film resistors and polyprop capacitors and the bulging PSU caps replaced with a set of AI Elko jobs and it is really nice, and I accept its shortcomings in the window rattling department.
There is a British kit amp on the market using EL84 in Push pull for less than £900, uses high quality transformers and based on a PCB. Has an integrated option which is basically a selector switch and volume pot which is all it needs unless you desire/need tone controls.(I can see the point in a tone control, I usually have my gear set at flat response but there are odd times I like to tweak something a little bit). Still may seem expensive but compared to the cost of a vintage amplifier that may need a bit of cash chucked at it to get it up to snuff they aren't bad value. And there's a good backup service and excellent build instructions.
Can anybody here do an equivalent price comparison with a 60's kit? I reckon the cost is about equal in terms of average wages, they were very expensive then too.

A.

[RojDW48]

Don't be mean to little SE amps. My little Tripletone stereo integrated thing has done sterling service connected to this computer for about 10 years, 2 or 3 hours a day every day. No room for a big TX in there! I know it's not hi-fi, but it makes a lovely noise. I have been tempted by some of these kits - but never given in.

[snowman_al]

I've never built one, but there are plenty of good and bad experiences aired on other forums.

If you have a basic understanding then the lack of instructions and support is not so important. If it is your first outing with valves then it can be a royal pain in the ... Read between the lines and there is a degree of disappointment with the performance, hum, low power and poor reliability for instance.

Then the other issue is most are supplied with 220 volt mains transformers so are being over-run by 20 or 25 volts on UK mains, shortening component life and sometimes transformer failure.

The kit bikerhifinut refers to would be my go to recommendation.
No Single Ended angst or Fairy Dust needed.
Alan

[Dickie]

I have spent some time listening to my cousin's ( an incurable audiophool) 300B SE amplifier. I came to the conclusion it didn't sound any different to my Radford STA15. I'm not sure what that says about my hearing or my Radford! Intrigued by this I measured its (the 300Bs) performance. Maximum output was about 6W rms. At 3W output THD approached 3-4%. Bandwidth was in excess of 20Hz to 20KHz.
The Radford's performance was largely in line with GJ's spec..
It must be said the 300B amplifier employs a serious amount of iron. Its output and mains trannies must be twice the volume of the Radfords. And the directly heated filaments are taken care of with regulated DC power feeds.

[Radio Wrangler]

Musical instruments, voices etc. all have significant harmonic components, so for simple music an amplifier can get away with a fair amount of distortion and no-one's the wiser. Just so long as the order of the distortion is simiar to instruments and voices. High order is much more noticeable, and odd more than even.

This fails to hide amp distortion when there is more than one dominant instrument. The amplifier, like each instrument, makes harmonics of each instrument. But unlike thr instruments, the amplifier creates intermodulation products between instruments.

So, on some music, favourable amplifier distortion can be unobvious or even good sounding, but not all music. This is why high-er distortion amplifiers are simply wrong if you just want to listen to the music as it originally was. Distorted amplification can sound fine, can be fun, can add character, I just object when claims of originality and accuracy get trotted out. There have been no such claims in this thread. Fun and enjoyment, yes. There is a theory that people turn up the wick until they detect some distortion as their reference for level.. until the system sounds to be 'trying'

Psychoacousyics, 90% psycho, 10% acoustics

David

[Hartley118]

Some listeners like the sound of even harmonic distortion and of course an issue with push-pull circuits is that they do tend to cancel it out. So it may be that single-ended output stages, particularly triodes with minimal negative feedback, do have some enhancing properties.

Back in the day of analogue tape, a judicious addition of second harmonic distortion could subjectively brighten a recording dulled by analogue tape. There was even a commercial studio gadget called the 'Aphex Enhancer' which actually added even harmonic distortion at high frequencies, as did some early highly regarded studio mixing desks with single-ended power transistor output stages. But that's another story..........

Martin

[barrymagrec]

I have no personal experience of Chinese valve amplifier kits but have read in a number of places that they sometimes have very marginally rated mains transformers due to a general assumption that Europe is all on 220 volts....

For the price though it may be possible to source a better transformer if the original proves to be poor.

[bikerhifinut]

To get back round to the original question.
I would opine that the main obstacle to seeing a supply of kit audio is simply one of supply and demand. And price, you'll never make something as good as a high quality commercial offering for less cost. Except maybe a valve amp, but they are expensive because the important main components can't be mass produced cheaply to a high quality. And we get back round to the other issue, it's not a cheap hobby in the main and it never really was if you got into building anything serious or substantial.
I strongly suspect my generation is the last that made things for fun or for economic reasons. I think it isnt just us and our interest in Radio and electronics in the broadest sense but in many other erstwhile popular hobby activities?
It does sadden me of course, but we live in a throwaway society where it's the norm to buy an item and then chuck it on the tip after 5 years or sometimes even less for the next "upgrade" be it a TV, a phone, or even a kettle or sofa.
I am slightly encouraged by my eldest nephew in his 30s with a couple of inquisitive sons who is keen for their great uncle (me) to involve them in the process of making things. But I fear they are a minority.
I'm a self confessed Audio enthusiast and have been fascinated by record players and amplifiers since I was a small child, I also love listening to music and the radio in general. At times I have wondered if I was slipping into what you guys call phool territory but I hope I have enough about me to identify the real from the imagined and one very real thing is that something I made myself that works the way i planned it always sounds better than the expensive commercial amp of similar power etc! What was that about 90% Psychological?

[bikerhifinut]

Just wondered, would the kids who experiment with raspberry pi and Arduino gadgets be like we were when we messed about with our first Regens and TRFs etc?
And maybe I just pine for a bygone age where the grass was always greener?

A.

[John Caswell]

Bikerhifinut wrote
"There is a British kit amp on the market using EL84 in Push pull for less than £900, uses high quality transformers and based on a PCB. Has an integrated option which is basically a selector switch and volume pot which is all it needs unless you desire/need tone controls."
If it is who I am thinking of, they also do a 30 watter based on KT88, hard wired, plus a phono stage, preamp, PSU and head phone amplifier all valve based and . truly hi fi quality. Output transformers are the highest quality consistent with sensible pricingThey are also very easy to upgrade or to use the modern idiot "make better with audiophool" components. Build instructions are top notch and backup is ditto
Here I have to admit being technically involved with these, but not financially, so have no axe to grind.

John

[DonaldStott]

Originally Posted by Edward Huggins

Given all of this, and the ability of most Members, there has been very little mention here of those apparently quite respectable Chinese amplifier kits that are held in stock in the UK (no prohibitive shipping) where for just over £200 one can buy an EL34 single-ended stereo amplifier and for a little more the PP version. All brand new of course.

Thanks Edward - any chance you could Post a link?

Originally Posted by John Caswell

Bikerhifinut wroteIf it is who I am thinking of, they also do a 30 watter based on KT88, hard wired, plus a phono stage, preamp, PSU and head phone amplifier all valve based and . truly hi fi quality. Output transformers are the highest quality consistent with sensible pricingThey are also very easy to upgrade or to use the modern idiot "make better with audiophool" components. Build instructions are top notch and backup is ditto

Thanks John - any chance you could Post a link?

[John10b]

I would be interested in a link also, thank you.
Cheers
John

[GrimJosef]

To save John's blushes, and because I have absolutely nothing at all to do with the company (except I did once, many years ago, buy one of their kits, which I liked) I think it's this http://www.world-designs.co.uk/.

Cheers,

GJ

[John Caswell]

Thankyou G-J the one and the same

John

[Ian - G4JQT]

Does anyone have an opinion on where the Gerry Wells WADAR amplifier fits in the valve amplifier field?