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Old 24th Aug 2023, 6:27 am   #1
steve ss
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Default Leak Stereo 30 rebuild

Quote:
Originally Posted by mastermanx2001 View Post
Just bought a Leak Stereo 30 transistor amp as a non worker. I knew that it has germanium transistors and expected the output transistors to be blown.

However, they seem Ok and the amp works! to my surprise, but as the volume control is increased the sound "motor boats" and if increased further sound cuts out all together. If volume is reduced all is well again. This happens on both channels. I can still get quite a good output before this motor boating.

I have some thoughts on what may be wrong, but would like the opinion of some of you very experienced guys.

Apart from this, the sound from this amps seems particularly good, better than I remember from a Leak Stereo 70 that I had. Could it be that the germanium transistors give a better sound, something to do with the lower volt drop across a germanium junction compared with a silicon junction?

Many thanks.
This is an old post that I was reading, similar to many others I have read regarding the Leak Stereo 30 and it's perceived lack of performance and the responses were often miss guided and in fact false.

It is assumed these units were / are poor performers for a variety of reasons again based on their current condition.

I chose the above example because it was better informed than many I've read.

In the 90's I worked on a lot of these as they were cool to own back then! and interestingly the owners more often than not found their newer amps were not cutting it against the rebuilt Leak 30's.

It seems like a timely idea since these amps are available, at the moment, for the price of a couple of pints at the local.

This is a quick run down on how to bring the Leak Stereo 30's back to their former glory.

First of all the do's and donts.

Do not replace the resistors except for those that are out of range.
(no metal film resistors).

All the electro's (red TCC etc) must be replaced, the best choice being the ELNA pink\orange RBLL low leakage electro's.

Use low leakage 35volt - 63volt caps. low ESR is not required!

Some of the original cap values are not available so go up to the next preferred value ie 80uF go to 100uF etc.

The output capacitors are 1000uF use 63 volt type but not low ESR, do not change this capacitor value.

The power supply capacitors are 2500uF and 1000uF 63 volt again not low ESR and do not change capacitor values.

The non electro's are all polypropylene say 50 volt ERO ie ROE (Eugene Roederstein) or Wima are the best.

Some general points of order.

Apply a little fresh solder to each joint and use a solder sucker before removing a component. (avoid Solderwick)

DO NOT! use lead free solder! (ie use 60/40 type)

Avoid heating up the circuit track as much as possible.

Insert electro's observing correct polarity (remember positive earth).

Only change one component at a time.

Be patient take your time.

Do not disturb bias pots.

Do not disturb the transistors.

Take some close up photos inside the case for future reference if needed.

Spray sparingly all the pots (using the tube provided) and switches with Servisol or CRC 2-26.

The rear fuses may need to be removed or loosened to change the output capacitors.

The capacitors on the HF filter do not need to be changed.

Check the lilliput bezel lamp is not blown,

Use 0.5 Amp slow blow fuse on supply side of transformer and 1.0 Amp fuse on amplifier side!

The three large DC filter capacitors need to be glued to the circuit board using Selley's Quick Grip ( yellow solvent based ) no super glue, hot glue gun or silicone!

If the original speaker plugs are missing use red and black banana plugs of the correct size. ( No ugly screw terminals retro fit thanks)!

I've heard these amps driving any number of quality speakers and give a good account of themselves,
for inefficient speakers use something else.

Once completed you can now enjoy an amplifier that approaches valve sound for, now at least, an affordable outlay!

The inevitable last question is always, is this it? The answer is no! There is a bag of tricks that can turn this amp into a real killer!!! but it is beyond the scope of this thread!

Suffice to say this thread will get you 90% there the other 10% is proprietary.

Steve ss.
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Last edited by Station X; 4th Sep 2023 at 9:11 am. Reason: Quote attributed.
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Old 24th Aug 2023, 8:22 am   #2
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Default Re: Leak Stereo 30 rebuild

Thanks for the interesting read Steve.

Can I ask why you specify "not low ESR" output capacitors?
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Old 24th Aug 2023, 9:53 am   #3
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Default Re: Leak Stereo 30 rebuild

Seconded, nice to see the solid-state Leaks appreciated.

I presume your notes apply to the original, germanium version, as opposed to the "plus" silicon one?

Quote:
The three large DC filter capacitors need to be glued to the circuit board using Selley's Quick Grip ( yellow solvent based ) no super glue, hot glue gun or silicone!
Why? And Selley's Quick Grip is not something we have here, AFAIK. Is it a contact adhesive, like UHU or Evo-Stik?

Nick.
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Old 7th Sep 2023, 5:32 pm   #4
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Default Re: Leak Stereo 30 rebuild

Ps. It may be of interest that Jimi Hendrix also used a Leak Stereo 30 amp as well as a Beogram 1000 Turntable (SRT deck B&O arm and B&O SP6-7 cartridge) and Lowther Acousta 115 folded horns using lowther
PM6A (Alnico) drivers giving a SPl of 105db /watt.( no not a miss print).

Here is a link to a recreation of his flat and his hifi gear.

Well worth a visit!


https://theluxereview.com/2020/11/27...rience-london/

Ok! A few points low ESR caps change the loading and "effective" impedance of the cct. and this changes the "voicing" of the original sound, so is not desirable as I like the valve sound this amp can give.

No2 These notes only apply to the Leak Stereo 30 (germanium transistors) amps. Not Leak stereo 30 plus, Stereo 70 or the Delta series amplifiers.

No3 Any semi flexible (yellow solvent based style ) glue will work and allow the capacitors to be removed without damage to the circuit board
at a later date. Super glue will damage the cct board. Silicon and hot gun
glue are not stable and the bond can let go without warning!

enjoy!

Steve ss.
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Old 7th Sep 2023, 8:23 pm   #5
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Default Re: Leak Stereo 30 rebuild

Whilst I strongly disagree with much of the OP, these can be an interesting amplifier. They seem VERY variable between samples for a start. Many sound awful but if you get a good one...

I have one here which I've not powered up for about 13 years or so. When I first tried to bring it back to life after decades dormant I brought it up on the variac like yer do but although no smoke or overheating and most things looking good there was no sound.... Well I've never known anything to need so much switch cleaner as this did!! I left it on for a laugh whilst doing it and as more and more Servisol was squirted into switches and pots and as I nearly ended up with blisters from working the controls so much (slight exaggeration) each channel came on, about ten mins apart, and then the tone controls and filters worked and started to sound half decent and... anyway to get to the point it ended up sounding amazing! So amazing in fact that I switched it off and put it away and haven't powered it up since! Hey I repair, modify, design and build often several £k hi fi gear for a living... it had to disappear before any hifi mates heard it and started asking awkward questions

The 30 Plus and 70 Plus OTOH are much more predictable but never sound better than average- IMHO
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Old 7th Sep 2023, 10:04 pm   #6
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Default Re: Leak Stereo 30 rebuild

The stereo 30 dates from before techniques were developed to give good, stable control of bias currents over temperature. So there's no surprise that different examples behave differently and sound different. Doing almost anything to them, especially involving the output transistors and related components risks causing significant changes to their behaviour.

Higher ESR in capacitors can be what keeps dodgy stages stable. Put in modern capacitors with extra-low impedances right the way up to RF - the sorts now needed for SMPS and formerly stable circuits can become 'frolicsome'. Instability can affect bias currents, offset voltages, and distortion. In general, it isn't good. Even if things sound OK, they can't be trusted to stay that way.

I think this series of Leak amps were rather good looking from a product design point of view, but the innards were disappointing. With later models Leak got the things progressively more dependable, but by the end, the circuitry was nothing special and gave average behaviour. Transistor amplifier design techniques still had a few mountains to climb... in fact a few mountains to even find Yes, the benefits were approaching the law of diminishing returns zone, but the improvements waiting around the next bend were better done than ignored.

It was an interesting time to be active. Several companies with a past record of some reasonable valve amplifiers were having to teach themselves how to design decent transistor amplifiers. I watched the arrival of the Leaks and the Quad and also some of quite different provenance like B arney Oliver's amp, and the thoughts of Matti Otala. Interesting times. Transistors are not like valves at all. They have different strengths and weaknesses. Completely different circuit design techniques are needed to overcome their failings. Valves have plenty enough imperfections, but they are different.

THe Stereo 30, the Quad 303 and so on are interesting stages in building an understanding of how design evolved.

(Sorry I was in a hurry on Tuesday. Given time, you could have had a look at the old Acos Rega turntable in the back of the car)

David
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Old 8th Sep 2023, 12:13 am   #7
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Default Re: Leak Stereo 30 rebuild

Indeed it was most unfortunate that that road works on the M1 affected play but I'm sure we'd have had a good chewing of the fat on many matters electronic

The Toby and Dinsdale amp.. erm I mean Leak Stereo 30 () was a very early SS model and like you say and I mentioned above there were many variables at play... It has been said that Leak had to get transistors pre matched into gain and leakage etc groups by the manufacturers for the Stereo 30 even. I've heard maybe half a dozen of these over the years which have varied from quite awful through not bad to the one I have which was truly impressive.

I wish the 70's had been my era in some ways as I'm still building on some of the work done back then... just when you're at the top of your game things start moving towards class D and "all digital" amps... I think there's hopefully still enough mileage in pure analogue for hi fi to keep me going for now though.

As to valves and transistors well that's why much of may work latterly has been hybrids (many call a SS amp with a valve buffer a hybrid but that's not in fitting with my own nomenclature!). Valves make great voltage amps and transistors/mosfets make great followers...and bootstrap drivers! Put them together and you get the best of both worlds.

I really can't see much likelihood of issues with low ESR caps in such as the Stereo 30 BTW! Not enough transconductance or bandwidth going on anywhere there As to Leak having "voiced" them back in the day... hmm.. no comment!

Hope the young gee gee's behaved themselves
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Old 8th Sep 2023, 7:40 am   #8
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Default Re: Leak Stereo 30 rebuild

Quote: Jez1234
Heptode.. anyway to get to the point it (Leak Stereo 30 amp) ended up sounding amazing! So amazing in fact that I switched it off and put it away and haven't powered it up since! Hey I repair, modify, design and build often several £k hi fi gear for a living... it had to disappear before any hifi mates heard it and started asking awkward questions!

Er! enough said.

It is often reported / miss reported or assumed that Tobey/Dinsdale were
design and "engineeringly" challenged by transistor amplifier topology, which in fact is another false idea that has been perpetuated for some time.
Indeed their level of understanding and insight was well up to the task!
to the point that Harold "nicked" their design.(as has been reported /documented anecdotally).

Harold did AB tests with the Stereo 30 against his own (Stereo 20) valve amplifiers with reported ("near" my words) "identical results"! no mean feat.
This performance was to the point that many Radio and TV stations adopted the Leak Stereo 30's as their ON Air / monitoring amplifiers,and these amplifiers were shipped all over the world for broadcast work so
reliability was also a priority.

On a technical note germanium output transistors are easily biased out of the "cross over distortion" area unlike silicon devices.

Their lower ft (gain/bandwidth) makes them less prone to out of band
oscillation and zobel networks are typically not required.

"Better" topology and better specs often don't cut it in the real world.

The saying goes "If it measures poorly but sounds great you have measured the wrong thing!"

I noticed Matti Otala mentioned, on a similar vein Ed (Eddy) Cherry

( Monash University Professor) demonstrated an amplifier he designed, at the 1984 AES using nested feedback with a reported distortion of 12 PPM (no mistake!) and indeed
sounded very good (it is reported he sold the design to Pioneer for an appropriately large sum) and being an academic was keen to demonstrate / expose some common misconceptions about amplifier requirements for an acceptable listening experience.

We listened to a classical music track first, very nice, and he made some
adjustments to the amplifier and replayed the the same track, he repeated this once more and the asked for comments on any perceived changes in the sound quality and everyone myself included detected no change.

He then pointed that he had introduced 2% and then 5% THD to the amplifier output stage and the audience was unable to detect the difference hence "proving" that any typical hfi amplifier
would easily be able to exceed these requirements and there was no
requirement for exotic high end amplifiers (such as his own)."RIGHT?"

Er! not so fast, as I pointed out to him after the demonstration.
Firstly he had introduced only 2nd harmonic distortion not THD, that
is due to the impeccable behavior of the rest of the amplifier and
2nd harmonic distortion up to 10% is hard to detect as it is musically
related where as high odd order products ie 7th harmonic are offensive
at very low levels.
So his argument was in reality the reverse that impeccable amplifiers
or as JLH would say above reproach are indeed the order of the day.

Speaking of JLH (John Linsley Hood), some years back I built a modified version of his classic 10W class A amplifier from 1969 and all I can say is
that for 99.9% of all hifi listeners this is probably all you need!(assuming
reasonably efficient speakers).
I well remember running it against a mega dollar ZEN fet (I think) class A
amplifier at the hifi (Lowther club) and seeing the stunned surprised look of the owner of the ZEN after a couple of tracks on the JLH amplifier.

Hmmm Yes!

And if this is not your cup of tea then may I suggest perhaps a
rebuild Leak Stereo 30 amplifier, you will be in good company with the
likes of dare I say Jimi Hendrix.

Enjoy
Steve ss.
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Old 8th Sep 2023, 8:05 am   #9
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Default Re: Leak Stereo 30 rebuild

I am puzzled as to why the OP says "Do not replace the resistors except for those that are out of range.
(no metal film resistors)."
I replaced the noisy carbon resistors in the front end of mine with metal film and got a dramatic reduction in hiss.

Peter
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Old 8th Sep 2023, 9:37 am   #10
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Default Re: Leak Stereo 30 rebuild

Ed Cherry's papers made it to the UK and were read with interest and appreciation in our lab by those with an interest in audio.

JLH's class-A design was decent, straight-forward and has stood the test of time. Class-A designs avoid crossover artefacts and issues of bias stability so they get an easy ride. JLH's other audio designs are more mainstream and average. Maybe there was an element of luck in that class-A amplifier? JLH certainly didn't understand the noise analysis of series versus shunt feedback arrangements in RIAA stages and this was aired in the WW letters pages.

In power transistors, some germanium ones gave higher Ft than some of the early silicon ones. Germanium isn't naturally slow. Some quite high performance RF/microwave types are made in a compound Si-Ge material as an alternative to GaAs. Not well known outside of the noise business, GaAs devices give rather poor noise performance below a few hundred MHz where silicon far out-performs them. It was the thermal limitations that drove things away from germanium, and now the price of the raw material.

There are two sorts of instabilities to beware of. One involves an intentional feedback loop, one you can see on a circuit diagram. Stability can be assessed on a bode plot of the loop gain/phase. Strays, transformers and so on can add unwanted poles and rob gain/phase stability margin.

The second one relates to stability of a device without any overt loop around it. Transistors aren't purely unilateral, signals entering their output do pass with some loss, to emerge from their input. If a transistor is embedded in a circuit where the impedances presented to their input and output ports are reflective at RF, there can be enough gain in a to-fro-to-fro path to sustain RF oscillation. This is where stopper resistors get brought into play. Valves are not immune to this problem. One of the most difficult circuits to get reliably stable is an emitter follower, especially if there are filter circuits around with RF type capacitors to a common ground. Track inductance can be gyrated by device gain and strays into a negative resistive impedance which excites and energises resonances into self-oscillation.

David
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Old 8th Sep 2023, 10:46 am   #11
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Default Re: Leak Stereo 30 rebuild

I overhauled and reviewed both the Stereo 30 and the Stereo 30 Plus for Hi-Fi News, here's the 30 plus review:

https://www.hifinews.com/content/lea...plus-amplifier

Leak claimed that the original one was an improvement on the Stereo 20; I tend to agree but then I don't really like that thick, muzzy, full of distortion and near unity damping factor small valve amplifier sound.

I thought that the 30 Plus was a better performer but the reliability is dubious due in no small part to those wretched edge connectors. Adding all that hand wiring seemed a backwards step given that the original Stereo 30 was more or less a single board design.

Much as I was surprised by the performance of the original Stereo 30 you can't make a silk purse from a sow's ear. It remains noisy and although reasonably tidy at moderate levels the sound completely falls apart when you turn it up a bit. No ammount of tinkering with resistors and capacitors will solve this, it is fundemental to the design of the amplifier and the major components used. However, the Stereo 30 (both versions) remain cheap and availalbe to fiddle about with, their best point.

These were times of progress though, it was probably one of the best of the early Ge designs. However, if you compare it directly with something like a Sony TA-88 of only a few years later you can see / hear the obvious improvements that advancing technology quickly made.
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Old 8th Sep 2023, 1:01 pm   #12
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Default Re: Leak Stereo 30 rebuild

Nice to see you back, Tim!
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Old 8th Sep 2023, 2:32 pm   #13
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Default Re: Leak Stereo 30 rebuild

Quote:
Originally Posted by Studio263 View Post
I overhauled and reviewed both the Stereo 30 and the Stereo 30 Plus for Hi-Fi News, here's the 30 plus review:

https://www.hifinews.com/content/lea...plus-amplifier

Leak claimed that the original one was an improvement on the Stereo 20; I tend to agree but then I don't really like that thick, muzzy, full of distortion and near unity damping factor small valve amplifier sound.

I thought that the 30 Plus was a better performer but the reliability is dubious due in no small part to those wretched edge connectors. Adding all that hand wiring seemed a backwards step given that the original Stereo 30 was more or less a single board design.

Much as I was surprised by the performance of the original Stereo 30 you can't make a silk purse from a sow's ear. It remains noisy and although reasonably tidy at moderate levels the sound completely falls apart when you turn it up a bit. No ammount of tinkering with resistors and capacitors will solve this, it is fundemental to the design of the amplifier and the major components used. However, the Stereo 30 (both versions) remain cheap and availalbe to fiddle about with, their best point.

These were times of progress though, it was probably one of the best of the early Ge designs. However, if you compare it directly with something like a Sony TA-88 of only a few years later you can see / hear the obvious improvements that advancing technology quickly made.
That must have been a very poorly Stereo 20 you heard! When properly rebuilt, with fresh valves, and especially IMHO when gilded by some modifications to improve the "stiffness" of the supply they sound simply superb and in fact in a completely different league to the Stereo 30 Plus and to Stereo 30. I design/build/repair/modify hi fi amplifiers for a living and I regard my Stereo 20 in many ways as a reference, in as much as it does so much right and so little wrong that if any other amplifier sounds obviously dissimilar then there is something wrong with it. I'm not claiming it to be an "absolute reference" in all regards but in terms of sound staging, imaging and "speakers disappearing" it comes close In fact one of the best sounding systems I've ever heard at any price was a Stereo 20 I modified far more extensively (separate solid state regulated supplies for every stage of each channel) for a late friend of mine driving his Quad ELS speakers. Even into moving coil speakers (Spendor SP1's) this one beat my friends Exposure 4 Dual Regulated into a cocked hat on everything but max volume. Yes it had tighter bass and greater transparency etc.

I agree with the points you made about the Stereo 30 in that yes the phono stage is too noisy to really be usable and it's best regarded as an amplifier of maybe 6-7WPC as it loses it much above this. As I said earlier I've heard at least 6-7 of these and all have sounded somewhat different with only the one unit sounding good to my ears. In fact the one's which failed to cut the mustard sounded rather like your description of the Stereo 20 to me!

On the Stereo 30 Plus and indeed 70 Plus (and Delta versions) I've heard probably a dozen or more examples and own (I'd have to hunt around in the back of cupboards to be sure!) probably 4 or 5 at least. I find these predictable in that all samples sound the same, as one would hope, but rather lacklustre. I've always thought them to be an amplifier that sounds perfectly acceptable so long as you don't compare them to anything better... if you see what I mean! IE nothing sticks out like a sore thumb as being wrong with the sound of them and thereby "spoils the sauce for too much salt". I once rebuilt a Delta 30 for a friend using all top quality modern components, 1% metal film resistors, low ESR top spec electrolytics, much bigger smoothing cap and speaker coupling caps etc etc plus careful set-up on the bench and it made only a very slight improvement. The problem appears to be the basic design of it.

My favourite overall of the Leak SS units is in fact the Delta 75 receiver. The amp section is basically a Delta 70 but as it came later than the 70 they had the opportunity to make some small but subjectively important changes to the circuitry and, to my ears, it is easily the pick of the crop.
You also get the very decent Stereofetic tuner thrown in!

The 2000 series of electronics was their nadir IMHO, amplifier wise anyway.
Both the amps and tuners were very high tech and modern for the time, at least as much as most of the Japanese competition in fact, and the tuners are good but the amps... oh dear... one of the worst sounding designs I've heard I'm afraid. If one wanted to know what is meant by "transistory sounding" then this is as good an example as I can think of!

I do really like the styling of the Delta 30 and 70! When this has come up in the past of hi fi fora I seem to have been very much in the minority on this one though.... The earlier Stereo 30 and 70 were apparently styled after Leica cameras which Harold Leak was a fan of.
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Old 10th Sep 2023, 3:51 pm   #14
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Default Re: Leak Stereo 30 rebuild

Quote:
Originally Posted by Jez1234 View Post
That must have been a very poorly Stereo 20 you heard!
You don't have to agree with me, but Leak (who made the wretched things) claimed that the Stereo 30 was an improvement over the Stereo 20 too. Was there a measured parameter where it was actually worse?

I've heard Stereo 20's many times but however they are ruined (sorry - 'upgraded') they remain at best in the 'OK' category to my ear. I know some people only listen quietly and so don't need a lot of power and like a sound which is thick with distortion harmonics further muddied by loudspeaker resonances caused by very low damping factors and for them a small valve amplifier is ideal. To me though this sort of presentation is like dosing yourself up with really strong cough syrup to get over a nasty cold - pleasant enough in the short term but a relief to leave behind once its over.

I did like the Quad II though, but only when used with the QC22 control unit. Forum member Grim Josef provided me with an excellent set for a review some years ago and I really enjoyed using it, although perhaps not quite enough to warrant the cost of a nice original example these days.
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Old 10th Sep 2023, 5:28 pm   #15
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Default Re: Leak Stereo 30 rebuild

I certainly don't have to agree with you and in fact, sorry, but I couldn't disagree more strongly with literally everything you said there!!

1. Measured parameters are irrelevant beyond a certain point.

2. I consider the Stereo 20 better than the 30 or any of the solid state models by a similar degree to which a modern 5 core PC is better than a ZX80.

3. The Stereo 20 sounds exactly the opposite of how you say it sounds. It has low colouration, no muddling, very tight well damped bass and no audible distortion of any kind. I've heard standard ones with worn out valves, sick electrolytics, resistors well out of tolerance and driving unsuitable low efficiency speakers sound rather like that though yes. I use mine with Spendor speakers and have never heard it clip and cannot use all the power. I have often had it at volumes where you feel the bass in your ribs!

4. The Stereo 20 is better than the Quad II

5. Old valve power amps should be modified as much as possible and never left standard in my opinion. Only then can you hear what they are really capable of when freed from the shackles of ancient components etc. None of this should be irreversible and no new holes should be drilled in the chassis etc. It must be possible to put it back to bog standard.

6. As someone who repairs and modifies amps (also designs and builds. I was chief engineer with Alchemist Products and worked for Musical Fidelity also before going self employed) for a living I get to hear a lot of amps and I've heard only a handful I consider better than the Stereo 20. Yes at any price! Of vintage valve amps the only one I've heard that does sound better still was the Radford STA25, which sounds simply stunning.

A Stereo 20 wipes the floor with Quad 303 and 405 for a start. It's simply in a different league.
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Old 10th Sep 2023, 6:03 pm   #16
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Default Re: Leak Stereo 30 rebuild

Oh and "Studio263", I reckon it's best we leave it at that point rather than a recursive utterly disagreeing with each other!
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Old 10th Sep 2023, 7:19 pm   #17
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Default Re: Leak Stereo 30 rebuild

OK, whatever pushes your button...

Personally I'd call them 'nice-fi' rather than 'hi-fi', but it takes all sorts. It always pays to be open minded when it comes to hi-fi; I've heard a lot of different equipment in my time at HFN but I don't hold the Leak designs in the same regard that you do. We all have our favourites, that's what makes it fun.
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Old 26th Sep 2023, 4:37 am   #18
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Default Re: Leak Stereo 30 rebuild

Quote:
Originally Posted by Jez1234 View Post
I get to hear a lot of amps and I've heard only a handful I consider better than the Stereo 20. Yes at any price! Of vintage valve amps the only one I've heard that does sound better still was the Radford STA25, which sounds simply stunning.

A Stereo 20 wipes the floor with Quad 303 and 405 for a start. It's simply in a different league.
Ok a couple of points.
As stated above the Leak Stereo 20 is a fine sounding amp along with trioded
Radford STA15's drive Quad ESL57's to "perfection" (my words).
No mean feat, this is praise indeed!

Note :Quad ESL57's compress with more than 10watts (RMS) input so any level above this is at the price of non linearity!

Yes the Quad11 /22 amps can sound very good but are out classed by the Leak and Radford.

Modified Quad 33/303's can sound very good also. (not in valve class though)
The latter Quad current dumping amps lost the plot!

Er! Back to the Leak Stereo 30

Quote:
Originally Posted by Jez1234 View Post
anyway to get to the point it ended up sounding amazing! So amazing in fact that I switched it off and put it away and haven't powered it up since! Hey I repair, modify, design and build often several £k hi fi gear for a living... it had to disappear before any hifi mates heard it and started asking awkward questions
For those that require replacement resistors I would recommend Allen Bradley type
which are very suitable and available in the UK. (see link below)

https://www.hificollective.co.uk/com...resistors.html

Contact us

CONTACT DETAILS:

ADDRESS:

HiFi Collective Ltd
Unit 47 Potters Lane
Kiln Farm
Milton Keynes
Buckinghamshire
MK11 3HQ
United Kingdom


TELEPHONE:

00 44 (0)1908 635953

E-MAIL:

sales@hificollective.co.uk

IMPORTANT NOTE - If you are contacting us regarding your order, please quote your Invoice Number.

For all technical enquires or to contact Nick Lucas please e-mail info@hificollective.co.uk

The note about moisture issue I have not experienced and normal use will
stabilize this in due course.


For those that require AC107 transistors these are also available in the UK
(see link below)
https://www.langrex.co.uk/products/a...w-black-glass/

https://www.ebay.com.au/itm/262942195776
Business seller information
LANGREX
JAMES RHODES
Unit 4
Daux Road
Billingshurst
West Sussex
RH14 9SJ
United Kingdom
Phone: 01403785600

Email: jamesatlangrex@aol.com
Value Added Tax number:
GB 923283921

If you need Any AC107's you need to be quick as they only have 17,601 left!
Perhaps on a more serious note if you want some realy quiet AC107's with hfe 70 approx.matched pairs are required maybe you could slip them a "fiver" for the trouble!

Also: Note If you choose to try some "mods"! do it to one channel only so you can
do a direct comparison with the original and not loose you way! If successful
you can then apply it to the other channel.

So how will the rebuilt Leak Stereo 30 sound?
(see link below)
This clip is typical for a rebuilt Stereo 30 amplifier.

https://youtu.be/beq9VWO0iC0

Er! just one more point.

Quote:
Originally Posted by Jez1234 View Post
The earlier Stereo 30 and 70 were apparently styled after Leica cameras which Harold Leak was a fan of.
Yes those responsible were:

Leak Stereo 30 Styled by Noël Haring Associates.(for enhanced appearance
in your home)

Having graduated in Design from The Royal College of Art in 1957,
Noël Haring started his own industrial and graphic design business,
"Noël Haring Associates"

That is about it!

Enjoy
Steve ss.
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