Taking a leak

Morning all. I'm after a leak stereo 70 amplifier. Anyone got one for sale please? I've got two pairs of leak sandwich 600s which I'm driving with the absolutely fantastic sansui AU 717 amplifier.
but I really would like the calmer leak stereo 70. Thanks in advance

 

Unless you want one for "vintage" or "authenticity" reasons I wouldn't bother if I were you. They are commonly available at a low price but they don't sound much good. Any cheapest in the range modern ish S/H budget amp will thrash a Stereo 70... or Stereo 30 Plus or a Delta 70 or 30. Delta's are updated re-styled versions and the 30's are basically the same as 70's but lower voltage power supplies etc and sound much the same as 70's.

 

Morning. I listened to one (leak stereo 70) at audio gold (park Rd London n8) hooked up to a pair of celestion ditton 44s with a garrard 401 turntable (sme 3009 tone arm) and I have to say I was mightily impressed. Anyway I appreciate your input mate.

 

Big speakers, find a well recorded record, volume turned up etc, unfamiliar system and room acoustics... pretty much any amplifier will be good enough to sound impressive, at least initially

They don't sound awful as such and can be reliable but the description of them I've used several times in the past is that they sound perfectly OK until you compare them with pretty much anything more modern or which was simply better and more expensive back in the day. IE nothing in particular sticks out like a sore thumb as being wrong with them but if you then swap one over with even the likes of a NAD 3020 or any budget Denon etc then the "modern" amp will beat it in every way.

I own several, have repaired many and even rebuilt a couple with top spec modern components and much bigger smoothing capacitors and output coupling capacitors just to see if it turned it into something special.... 'fraid not!

The Matching Stereofetic tuner is very good and there was a wooden sleeve that would take the pair together and looks good. I have such a thing amongst my own collection and used them for a while in a vintage second system with Leak Mini-Sandwich speakers. Sound was nowt special to say the least but it looked good!

If you must have one 'cos you love the styling or your Dad used to have one then obviously each to their own and I hope you'll enjoy it

To be historically accurate though the "correct" range to go with your 600 speakers is the Delta range. The Stereo 70 came out in 1967 and was updated to the Delta 70 in 1971 after Leak had been bought out by the Rank Organisation. It's basically a re-styled Stereo 70 but looks more modern. The 150, 200 and 600 speakers were released to go with the Delta range. A matching Leak turntable was also available but it was actually a Goldring-Lenco GL75 with a Leak badge on the front!


The star of the Leak solid state range in my opinion was the Delta 75 receiver. These are basically the circuitry of the Stereo 70 and the Stereofetic (AKA Delta 70 and Delta FM) combined in one case BUT they came out a year or two later and both amp and tuner circuitry was modified and improved in the receiver. It is considerably better sounding than the separate amp and tuner. Avoid the later 2000 series amps!

Be aware that as these are all around 55 years old now any unit you buy will need a complete refurb and service including all electrolytic capacitors replacing if you want to hear them at their best and get reliable service from them. It's normal to find the main big smoothing and output caps bulging and some leakage from them in even still working units...

To get this work carried out properly will cost a lot more than the value of the amp itself. I'd be very wary personally of units being sold as "completely rebuilt/refurbished" for only £185! Obviously you can save a lot if you can do the work yourself.

I service these (and the majority of other amps etc) in the North East (and indeed nationally by the wonder of couriers!) but there are companies such as London Sound nearer home to you. Expect to pay £40 - £80 for the amp and £200 - £350 ish (depending on whats wrong and how far you want it taking etc) for a proper refurbishment and service job by a professional.

 

Hi Keats, here's my sorry tale. A year ago, on a whim, I snagged a Delta 70 locally for £70 from a seller advertising on Marketplace. A couple more went on ebay in quick succession last week also for the £70 mark. The seller insisted on me demo-ing it, despite me saying I'd fix it either way. I listened to it at his place and he kept telling me how great it was but in truth it was mediocre even by 70's standards. By the time I got home it had ceased working. It blew the 5A rectifier fuse. I put it to one side as I've had too many projects up until now.

The Delta is now completely disassembled on my bench ready for a complete top to bottom re-build. I'm glad I completely took it apart as that has revealed so many problems that need fixing. I started by de-soldering all the electrolytics to check them all. Some seemed okay-ish, some borderline and some way out of spec. In truth, after 50 years, they all need replacing. Next up the tubular carbon film resistors on the power boards. All of these were at least 50% out of spec. These will all need replacing, as will all the ones on the pre-amp boards. All the standard 1/4? watt carbon films tested good. Remarkably.

In the course of de-soldering these components some of the tracks popped (audibly) away from the board in places. Other owners have experienced this too. I've had to carefully epoxy these back down. All the card edge connectors were smothered in globs of solder. I cleaned all this off with wick to discover two partially broken edge connector pads. I've repaired these with nickel paint pen - for now.

Next the rectifier diodes. 3 good, 1 bad. The voltage drop was hopping around between 0.5 and 1.5 volts. That's probably what blew the fuse. I may as well replace all 4, while I'm in there. It took me a while, though, to work out how the primary and secondary winding are arranged, (very strangely as it happens). The paxolin tag strip connected to the output trannies is practically disintegrating and will need replacing.

Elsewhere lots of connecting wires literally just dropped off when I touched them. Brittle, dried out solder. The AC live wire coming from the on/off switch had a dry joint and was connected but loose, which probably also contributed to the fuse popping. Other wires had previously been replaced but with the wrong gauge (too thin). This thing may need a full re-wire. To cap it all, it absolutely stinks - from 50 years of accumulated nicotine and tar. So, the whole lot's going to have to go in an ultrasonic cleaner.

To put all this in perspective, I enjoy doing this stuff, just for fun. I'm building a retro 70's/early 80's system - Garrard changer with KEF Carlton III's. I'm retired. I have the time and skills to do the work. This amount of work just isn't economical if you have to pay someone to do it for you. OTOH if you don't do the work, you won't have a working amp for very long, I suspect.

Finally, last week I bagged a Marantz PM44SE for £60 posted. I used to own one of these back in the day and really loved it. All I had to do to repair this was disassemble and thoroughly clean the volume pot. I didn't realize before that it's brimming with ELNA cerafines & polystyrene caps, like they've been breeding in there. All giving a wonderful sounding 45 watts per channel of clean, dynamic, musical power which beats any Leak with a soiled stick. I'd love to hear that Sansui and compare it to the capable but budget Marantz.

 

Morning all. Thanks for the interesting informative replys. Yesterday I bought a lovely recently re capped nad 3020 a for £250 and I have to say the little nad has a big swagger driving the 4 40 watt leak 600s pretty sweetly. Compared to my sui 717 there is no comparison due to suis inner core strength the leaks were/are scared of jap sui and seem much more relaxed working with brit nad have a good day everyone

 

Sui would slap up that marantz mate all night long. Not many if any intergraded amplifiers 100 Watts or under can take on the sui 717. Those who know know

 

Piggy mate you sound like a man that knows his way around circuitry tracks? Any good with vintage CB multimode 10/11 meter radios?

 

If you are mate I can put a lot of work your way if your interested?

 

Hi Keats, you lost me at CB lol. Sorry, not my bag. The NAD looks like a decent buy if it has been re-capped. You want to check that. There's a lot of BS'ers around especially on the flea.

 

I really enjoyed reading this thread - lots of constructive information and nice to know there are people around who are tuned - in to the problems relating to vintage kit.

Only my Quad 33's have been a bit of a problem since 1971 when I bought the first. I recently decided, it/they deserve to be retired and went for a Sugden Bijou Head Master, which is gloriously retro - "Bauhaus". My 303 (1971) and 405 are still going strong and Quad have maintained them for me, for not to much money.

However, to compliment the Sugden, I bought a Quad 909, so feel like I have stepped into the 21century for the first time - yes I know the 909 and the Sugden are a little dated. But to me, they are very modern and sound glorious.

 

Was the Nad from Audio Gold?

 

I have 2 of these s70's in my loft along with a few more recent- a KA3700, from memory- you can't have too many amps. I agree the sound was not great on the Leask, even though back in the day I thought it was. in the late 60's/early 70s when a mate of ours elder bother had one...and we were still satisfied with 10w mono transistor amps. Even PROJECT Stereo 60 was a reasonable sound. The restoration of a leak is a passion I understand but the sound quality and lack of mid/bass is noticeable. I have 3 more modern amps which are far more pleasing and cost a song to buy/repair/recondition- even one with STK Modules (yes, sourced from the Far East at a a risk.