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Leak TL12.1 [or Plus], Radford MA 15, or Quad II - Which?

George J

George J

Herefordshire member
I would also consider a Leak TL 10.1.

These are all veterans, so would require a complete rebuild, and that is certainly outside my skill to do well if at all.

This would be for my ESL in the long term, so that the outputs between 10 and 18 Watts RMS, would certainly be enough for my use on the ESL speaker that is rated - I believe - at 16 Watts RMS nominal maximum. I never listen at what anyone would call loud levels, so modest power of the first quality is all I need.

I hate redundancy so I am not interested in stereo and will stick with a mono power amp.

I have a good local restorer in mind for the work of restoration. These days it has to be local, and about twenty miles [possible when things settle down on the bus service] is reasonable. I can no longer consider the wonderful John Caswell [except for any potential repair to my Trough-Line, which he rebuilt so well last year] due to the logistics and the fairly regular servicing that any veteran valve based power amp is likely to require compared to a veteran tuner which should run without out issue for many years.

My favourites would be Leak and Radford, with a Quad II probably least favourite as I have a modern one [Q II Forty], and that will never leave even if it might go into back-up service alongside a rebuilt oldie. A little variety in function is fine and a good thing in my view.

I hope that the cognoscenti will be pleased to offer their thoughts, and help solidify my aim over the next twelve months. Even throw in some off the wall alternatives ... But I shall stick with a mono, transformer-output valve amp of lower power than the Q II Forty [which actually could produce more like 30 Watts RMS in the real world on an ESL]. The lower frequencies of the original ESL rises to a peak of nearly 50 ohms, which is helpful for a low powered amp. I often think the ESL only requires great stability and great quality, and power-wise really only needs a light breeze of power to work nicely. It will not ever be a truly loud loud speaker unless listened to as an array of multiple units. That might be impressive, and very good, but wasted on me, and impossible, being a potential irritant to neighbours.

Best wishes and looking forward to reading thoughts and suggestions from the community. George
 
Dear gassor,

The plan is a bit steadier than buying anything before the autumn. I want to feel secure about employment over the next few months.

But that does not mean I cannot do some information mining before starting.

I have long thought that either variant of TL 12 would suit me, but am also fascinated by the Radford ...

Unfortunately old Quad IIs seem to have gathered something of a cult regarding the price paid - I assume - by collectors rather than for daily use.

Best wishes from George
 
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Hello, George. Have you considered a Dynatron amplifier? I have used their LF11 model very satisfactorily in a mono FM radio arrangement using a Goodmans full-range loudspeaker. The LF11 is 2 x EL84s, so about 10 watts output I suppose, and uses a 5U4G rectifier valve in the power supply arrangements. Nice compact chassis finished in hammer green paint and looking every inch the part for a "vintage" system. I had mine comprehensively overhauled by Jez Arkless before putting it into use. At my request he fitted conventional loudspeaker output posts on flying leads, thereby avoiding the need to use the original speaker lead attachments. Lovely!
ML
 
Dear ml,

Thanks for a different suggestion. I would never have thought of Dynatron really. I suppose I grew up when the company was far from what it was in previous decades.

Best wishes from George
 
What a deliciously tantalising prospect.

The fact that you are looking for a single mono amp puts you in a strong position as a buyer as the vast majority of people are after pairs these days for stereo use. I think you have a very good chance of bagging a bargain.

I often see really interesting looking mono valve amps on ebay and what puts me off buying them is the fact I worry about my chances of finding a matching partner. No a problem for you!

The Leak 12.1 and Raford MA15 are certainly safe choices but are likely to command strong money.

I can't claim to have any firsthand experience with them but how about a nice Mullard 5-10 build? Or an Armstrong A10? Or Pye?
 
Dear Mike,

I was hoping to read your words here. I have been watching your latest thread on the Radford. It is a great pleasure to follow your threads like this!

And thanks for the other suggestions, which, as with others, will form the basis of research, before I buy the chosen amp for restoration.

Really I'd like something to run beside my Q II Forty, so that any breakdown does not leave me stranded. Like having two functional bikes. Things rarely go wrong when there is a substitute waiting in the wings!

Best wishes from George
 
George - how about adding a Philips AG-9000 to your list? I have a friend in France with an attic full of hi-fi, but what he really wants is another AG-9000 so he has a stereo pair. He loves the sound, and they are gloriously wacky looking. It would look great next to your Troughline. I have no idea what they fetch, but I’d be surprised if it was more than an MA15.
 
Half the fun here is going to be learning about many classical valve amplifiers!
Thanks for your suggestion, dear Marchbanks.

I always find that the more effort you put in the more enjoyment the end result yields. Just going into a shop, and paying the money does not really do it for me anymore, unless it is basic pleasure like Amber Leaf or Rioja!

Thanks to all and best wishes from George

PS: I have another project in mind for after this, but that will have to wait awhile. A sort valve based preamplifier that will have only one input, but stereo, and one output in mono. My idea would be three cathode followers - one each on the input stereo channels with attenuation down to nill as effective buffers from the source stereo outputs, and then the independently variable outputs of these running into the third cathode follower for output to the mono power amp. I know how nice an attenuated cathode follower can be from the Trough-Line, the output of which current feeds directly to my power amplifier. This stereo to mono pre-amp would allow me to feed my two channel digitally stored music to my ESL. For this pre-amp I have the idea of a donor chassis being a first variant Trough-Line. The mains transformer is more than just adequate, and the three valves required would be a lower load than the eight in the original radio. My guess is that three cathode followers [as per the one output stage of the old radio] would easily fit in the space the chassis provides, and the attenuators would easily be fitted where the tuning and of/on/vol control fit as new.
 
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My father found one of the mono leak valve amps with preamp, dumped. He repaired it. It had gold cases with a very thick umbilical cable connecting them. It used a pair of KT61 valves ( beam tetrodes or some thing). I was able to find a couple - very hard to find at the time. Not sure what

some thing like this
http://www.classiquesounds.co.uk/Images/leaktl10_lrg.jpg

and this as a preamp

https://i.ebayimg.com/images/g/IkkAAOSwRs1eMa5-/s-l500.jpg

both vanished when my father died and the house was cleared
 
I have always had a soft spot for the KT61, sort of a small KT66. I once built a Mullard 3-3 using a KT61 in place of the EL84 - worked splendidly.
 
I have an old mono valve amp that uses, IIRC, EL37's... you don't see those very often. Whilst I know where it is I can't be arsed to go move stuff to get at it and then remove the top cover to confirm it... They are certainly EL3something and look very old fashioned. I'd guesstimate it's about 20 - 30W output and is a "hi fi quality" (has negative feedback and prob <1% THD) public address type amp such as would once have amplified the output from the projector when a film was shown at the village hall or some such or maybe for playing glen miller records or bingo calling.... It looks kinda late 40's/early 50's but I seem to recall some parts inside being more like 62 ish and suspect that to be closer to the real date but that it made use of war surplus etc parts to keep the price down. Maybe. Battleship grey hammerite and probably from one of those ubiquitous "RSC", "Linear" etc makes you used to see in every "Practical Wireless" etc. Point to point hand wired. FFS I've nearly stimulated my own curiosity enough to go get the bugger now... but not quite:rolleyes:
 
That would be ideal - of course it would!

The trouble is really, I need to get it cheap!

No real spare money at least until my job transfers to the new owners in September.

But that Leak looks in unmolested condition. Unmolested and complete is far more to my liking that minty repainted and modified.

I'll PM you in the morning. Working tomorrow afternoon ...

Thanks from George
 
Well, I stopped at 569.-, sold for 603.-. To be sold on eBay soon at just over a £1000 I reckon - shame, it seemed a good one.
 
Thanks to Richard [Dowzer], I have had the excitement of watching a real time internet auction again! Thanks Richard!!

Obviously, I have probably missed the boat on this as the TL 12.1 has become sought after ...mostly and sadly as a speculation rather than to enjoy as meant as a mono amp in daily use.

About ten years ago I was restoring my Carlton [road bike, not Vauxhall/Lotus], and bough at realistic prices between two and three groupsets in the Super Record [also Nuovo Record, Gran Sport and "C" Record] Campagnolo parts. Enough to see me out ...

These came at prices lower than new parts then. Nowadays, I would not be happy paying the prices that vintage Campag parts sell for. I bought them to use, and so have no guilt about having a small hoard of spares! Seems the TL 12.1 is actually more expensive these days than what it would cost for a newly made thing! That is madness!

Mind you, I don't give up. One day I'll find one at a respectable price, and spend what it takes to restore it to as new electronic condition.

But Mr Tony L had a specifically brilliant suggestion and that is go for a TL 12 Plus [later variant of the 12.1], as these have yet to be over-valued. And by now are not nearly so rare. ...

Best wishes from George
 
The speaker is good for about 50w from an amp that does 50W into 8 Ohms (it's voltage that is the limitation) so I wouldn't worry about that aspect too much.

But obviously Radford.

On a budget, or while waiting for the right used chassis to turn up, you could consider making a JLH 'Class A' amp. In the spirit and should be a reliable backup.
 
Well this caused a nice bit of entertainment here in rainy Herefordshire, but it also crystallised in me another realisation.

The Quad II forty does not need to be improved on. In any case I doubt that sorting out a veteran would lead to an outright improvement so much as a slight change in character. Some things might seem better, and some less so. The odd thing about that sort of change is that you get used to it quickly and discount it terms of not noticing ...

Rob Flain [at Quad] was correct in his advice that the II Forty makes a good match with the ESL.

As I moved from a pair of One Thing Audio rebuilt ESLs to a single Huntingdon rebuilt speaker and from a stereo Naim NAP 100 to the mono Quad valve amp, I was delighted to have found a way to power the ESL in what seems a near ideal way.

So unless I won the Lottery [unlikely as I buy a ticket perhaps once in three years] I suspect that I have my final power amp already!

The old Trough-Line really still brings a few pleasant surprises. All the roof mount aerials for VHF/FM I have seen are set up for horizontal polarisation of the signal. So when I set up my wire dipole, I stretched it horizontally, and carefully aimed it at Sutton Coldfield, which is one the handful of the highest powered transmitters in the UK. However I was reading about the send from the transmitter, and it is mixed horizontal and vertical in polarisation.

As an experiment I let the dipole hang vertically [which removed the need to aim it] and tried it out like that. Very pleased with this. The Sutton Coldfield mast is unaltered in quality, but the other transmitters at Marcle Ridge [Herefordshire] and somewhere down by Cheltenham, are much improved. You never stop learning! Also the vertical dipole looks much tidier, less Heath Robinson than using it horizontally. That is called "win-win."

Thanks for all the lovely replies to this thread.

Best wishes from George
 
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