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Leak Stereo 30, 70 and Delta upgrades?

Arkless Electronics

Arkless Electronics

Trade: Amp design and repairs.
I was thinking it might be fun to soup up an old Stereo 70 into something to bother modern integrated amps... phono stage, line stage inc tone controls the lot... It could make a fun "street sleeper" :D

I'm wondering if there could be any mileage in it as a money earner as well though? I'm guessing not as it would involve a lot of work and wouldn't be cheap.. but there again the "retro" thing is popular nowadays.

I always really liked the styling of the Delta versions but not so much the earlier genuine Leak ones.

Just a daft idea really... Thoughts??
 
I had a dead Stereo 30 that I gave away, in fact I don't think that I did manage to give it away, I think I just stole the Bakelite knobs off it as spares for my Troughlines and binned the rest.
 
toprepairman said:
I rather like the early Stereo 30, germanium version with AD149's.
Way better than many people give credit for.
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Yeah I've got one and it sounds pretty impressive. They seem very variable from one sample to another IME, some sounding muddy and soft but a good 'un being quite impressive.
 
Radfordman said:
I have a couple of them, best sound is feeding signal into tape input:

Leaks by A60man, on Flickr
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Something's stirring in the little grey cells that if you used the tape input on the front panel it bypassed the tone controls... Maybe you can recall better?

I have a similar collection of those here..plus some later Delta gear which I vastly prefer the styling of. I really didn't like that styling. IIRC the textured black strip, from which the paint so easily comes off, was meant to look like the styling of Leica cameras, which H.J Leak had a fondness for.

Rank made a few small improvements to the original version internally as well, notably a bigger heatsink.
 
Many years ago I found my Dad's old Delta 30 in the loft. I had a Pioneer 6500 at the time, and thought the Delta would be better as "British" hifi was the rage in the early 1980s. Sadly, it wasn't better, in fact it was wholly and truly awful. Quite wahere Leak thought they were going when they went from valves to transistors, I really don't know. I bought a Stereo 20 soon after, and although I could never get the preamp to work well, the power amp lasted me decades, and if I still had it, I may well be using it with my Martin Logans.
 
I have always thought that a good amp with germanium output transistors could sound very nice. Perhaps it's something to do with the lower forward volt drop of germanium compared with silicon.
 
The 'muddy' sounding ones could just be down to dried out electrolytic caps within the audio circuitry.
Agree with the lower forward volt drop as well as a very gentle 'turn on' curve.
Those Stereofetic tuners can be very good too.
 
I believe it's more than caps and in fact has nothing to do with caps...

+1 On the Stereofetic tuner... I'm forever recommending these instead of the poor and vastly over rated Troughline!

Anyhow the whole point of starting this thread was to see what people thought of the idea of... well lets say redesigning them, to sound in another league to the original and to take on modern amps etc.... The originals sound poor but there would be no similarity with the original in sound quality after mods.
It was just a daft idea based on there being vast amounts of these cheaply available and the popularity of retro styling etc.
 
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Barrymagrec said:
Basically a new amp in a vintage retro case?
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Kind of yeah... Extensive mods to the original circuitry based on 45 years of advancements in both knowledge and components, including such things as conversion to complementary output stages and vast improvements to the phono and line stages. It's just a daft idea as I said as probably no one would pay the £300+ to do the conversion... Maybe true fans of retro want the retro period poor sound as well or only care about the retro appearance...
 
toprepairman said:
Ok, so nothing to do with caps, and the cause is....?
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It's long been a mystery to both myself and several others I've know that these do seem to vary hugely from one sample to the next... It was the early days of solid state and apparently they had special sets of matched or selected transistors delivered from their suppliers Mullard and GEC. I haven't had a look at the schematics but maybe things like bias sensitivity were not fully understood and therefore the circuits were over dependent on selected devices... maybe in the early days some batches of devices just didn't sound the same.. who knows. IME it is true though.
 
This sounds like a good fun project, go for it Jez:)

I prefer the aesthetics of the earlier Stereo 30/70 to the Delta series myself but I would think the Delta 70 is going to be the better one to mod because of the bigger heat sink. Having said that my Stereo 70 never gets more than slightly warm.

I fully rebuilt my own Stereo 70 a few years ago and it makes a great little second system with a pair Wharfedale Diamonds. During the rebuild it got all new electrolytic caps (uprated in a few places), new trim pots for setting the quiescent current and a bunch of drifted carbon resistors got changed to metal films. The only major departure from spec is that I decided to replace the 2N3055 output devices to MJ15003 (two of the original 2N3055 were blown). I also got a bit carried away and treated it to a lovely pair of 2200uF 100v Elna Cerafines as output coupling caps (worth a small fortune on ebay). I've often wonder how my Leak would stand up against a Quad 303.

I can't see too many people opting to send you their whole amp for a full-blown £300 rebuild....but you never know! There are plenty of these amps around and interest in vintage HiFi is certainly booming at the moment.

I think a popular alternative might be to develop some upgrade kits for the Stereo 30/70/Delta 70 which could be either fitted by yourself or supplied as a DIY option. For example you could sell replacement filter cap kits including all the clamps and fixings, replacement output coupling caps and various pre/power amp section upgrades, upgrade volume pots etc etc....

If you could develop some new upgrade pre-amp and power-amp PCB's which could simply be slotted in in place of the originals I can image those being very popular. Or maybe people could post their cards to you for modification?

I suppose I'm thinking more along the lines of what Dada offer for the Quad 303.

Good luck with the project, I shall be watching with great interest.
 
I suspect the main issue with this will be finding really nice EX or mint examples to restore. The Leaks and Armstrongs appear not to age too well and often tend to look pretty knackered cosmetically with rubs to the paintwork, missing or broken knobs etc. Another to add to the list is the orange Sugden A48, a very nice amp IMO and one to add to the list, but it was painted in that god-awful furry Nextel stuff that turns to tacky goo after a decade or two. Some Revox kit suffers this plight, as do the Meridian 100 series and the Quad 606.

It is a good idea though, but I suspect you would need to factor-in buying quite a few dead donor units just for cosmetic parts (I suspect you would for things like the Armstrong switches etc too, which will likeky either work perfectly or be junk the way say Quad 33 switches are). I know enough about this game to know condition is everything, no one will pay big money for tatty kit unless it is crazy rare and of legendary sound quality (Leak 12.1, Beam Echo, RCA mono amps etc).
 
I was only ever going to do the mods to Leak SS amps. No other makes or types. I thought it would probably be a non starter to be honest so I'll not bother. These are a twat to work on and the labour involved etc would mean a bill of £300 ish which would probably put most off... also, personally I'm the opposite of Tony in as much as I couldn't care less about condition re scratches, paint missing etc. That would be entirely up to the owner of the unit. It has to sound and measure 100% for me but looking tatty has no effect on this.

It's pretty much a case of no matter what amp is chosen for the treatment and no matter if it cost £200 or £2000 in today's money when new it is going to cost in the region of £300 to do this type of work....

I have no intention of making new plug in boards for them as I doubt there would be enough demand to justify the large outlay in time and money it would take. I would have done it by cutting tracks and adding extra parts to the other side of the boards etc. The plans for improved power amp performance would have meant completely removing the heatsink and surrounding components, drilling new holes in the heatsink for extra parts to be mounted and hopefully to add extra heatsinking to the inadequate ones already present. A big job!

I may go ahead with one "for a laugh" for my own use if I ever get round to it... It would be amusing at bake offs to have some old scruffy looking Stereo 70 blow away all sorts of expensive modern gear!

If anyone has ideas of gear which would be worthy of such modifications and people would be willing to pay that sort of money for the mods then I'm all ears.... The 303 is the obvious one and the likes of Dada seem to have that sewn up... I did offer much more extensive mods than anything they offer for the 303 but it was £350 20 years ago and not surprisingly there were no takers... apart from a few I did for a mate at special "mates rates".

My intention is not to restore but to re-design. "If they'd known in 1970 what I know now and if they'd had access to the components available today" if you see what I mean...

The old "keep it original" thing is a hurdle in some ways of course... the "if I'd wanted something that sounds THAT good and costs THAT much I'd have bought a modern amp" syndrome... I offer all sorts of mods for Stereo 20's but never get any takers as I suppose people want originality first and foremost.
 
The Stereo 20 along with most of Leak’s tube era is now a proper classic. It can hold its own against pretty much anything IMO assuming raw power is not a criteria. They are now very rare and collectible and the value is always inverse to the amount of mods they have had, so it is understandable why the vast majority of owners sympathetically restore to a high factory spec removing any past modifications in the process.

If I were you the things I’d be looking at modding would be the early ‘80s kit; Musical Fidelity P170s, Preamps, Magnum integrateds, power amps, the forgotten non-classic Sugdens, Myst etc. These are the real sleepers at the moment IMO and they should be simple to work on too as they tended to have a fair bit of air in the box! There were loads of good second-tier amps of this ‘black box’ era that never obtained the classic status of Naim and are now being forgotten.
 
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