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Old 6th Dec 2017, 10:20 pm   #41
vishalk
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

So i decided to go through all the component values for the ST20.

Now for some reason the components have changed values over the years?

For example on different wiring diagrams and lists of parts:

R5 can be 47k or 100k
R12 470k or 1M
R13 470k or 1M

C5 0.1uF or 0.02uF

My ST20 came with the original paperwork which has a wiring diagram, i took the values off of that.

So my question is which is right? I think perhaps just follow the wiring diagram my ST20 came with.
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Old 6th Dec 2017, 10:45 pm   #42
vishalk
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

I want to keep the parts UK made for some reason, prefer if it was all british makes.

Capacitors:

http://www.claritycap.co.uk/

Resistors:

Not sure! Any suggestions? ARCOL? top of the list is DALE/VISHAY

Thanks
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Old 6th Dec 2017, 11:49 pm   #43
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

I suspect you'll have problems sourcing British Made parts. Labelled or packed in Britain, perhaps.

The capacitors you suggest will no doubt perform just fine, but they'll cost plenty compared with plain vanilla good quality film capacitors for very little if any performance advantage.

Arcol (Ashburton Resistance COmpany Limited) is British (at any rate British based) but Vishay(-Dale) is American based and again likely manufactured anywhere. Vishay make no bones about having started out in precision resistors but then expanded by takeovers into a broadline component source. Dale was just another company they acquired with a decent reputation so still included by name in the resistor brand.

Have a look at the likes of Vishay and TYCO (Takes Your Company Over) and their history and you'll get the idea.

Plenty of globalisation to be found in electronic component manufacture and supply
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Old 7th Dec 2017, 12:37 am   #44
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

Quote:
Originally Posted by vishalk View Post
So i decided to go through all the component values for the ST20.

Now for some reason the components have changed values over the years?

For example on different wiring diagrams and lists of parts:

R5 can be 47k or 100k
R12 470k or 1M
R13 470k or 1M

C5 0.1uF or 0.02uF
Much of this happened when Leak discovered that they couldn't exceed the EL84's specifications and get away with it (with previous amplifiers the output valves had generous safety margins, but the EL84 doesn't). So they had to change the output transformer design and also some component values to stop the EL84s going into thermal runaway. The 47k/470k/0.1uF values relate to the later amplifiers which had type 8778 output transformers (you may have labels on the bottom of your transformers giving the type number). The earlier amps had type 3921. If your amp was an early one and it has been to Leak for a service then they will have changed the transformers. So the documentation won't necessarily match the transformers you have.

Cheers,

GJ
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Old 7th Dec 2017, 12:45 am   #45
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

Quote:
Originally Posted by vishalk View Post
I want to keep the parts UK made for some reason, prefer if it was all british makes.

Capacitors:

http://www.claritycap.co.uk/
You could also look at Ansar Supersound capacitors, available from Cricklewood Electronics for example. They're made in the UK.

Don't forget to check the physical size. The capacitors will have to fit into the spaces on the tagboard.

Cheers,

GJ
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Old 7th Dec 2017, 5:00 am   #46
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

As a yard stick, if the capacitor you are looking at is an "Audio" special from a HiFi supplier and is dearer than a run of the mill good make one from an electronics parts supplier like Cricklewood, the difference is the amount of male bovine waste material included.
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Old 7th Dec 2017, 8:15 pm   #47
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

It was a good day today, i took the ST20 to barry at vyse amps where we spent the day discussing and learning about the amplifier. Going over the basics of valve amplifiers, how they work, reading the schematics and how it all comes together.

After that it was a case of testing the transformers and voltages which were all fine.

As predicted many of the components had drifted , the power supply caps were leaky and way off. It was decided that all the components have to be changed, so i started with the capacitors first:

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I was also taught how to test the valves using the AVO ct160. Most of the valves were good and i was lucky enough to have a quad matched set of mullard el84's RESULT!

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Old 7th Dec 2017, 8:40 pm   #48
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

Quote:
Originally Posted by GrimJosef View Post
Much of this happened when Leak discovered that they couldn't exceed the EL84's specifications and get away with it (with previous amplifiers the output valves had generous safety margins, but the EL84 doesn't). So they had to change the output transformer design and also some component values to stop the EL84s going into thermal runaway. The 47k/470k/0.1uF values relate to the later amplifiers which had type 8778 output transformers (you may have labels on the bottom of your transformers giving the type number). The earlier amps had type 3921. If your amp was an early one and it has been to Leak for a service then they will have changed the transformers. So the documentation won't necessarily match the transformers you have.
Thanks Grim that was very helpful, the output transformers are 8778's.
So i will replace with what they were originally fitted with which were 47k/470k/0.1uF values.
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Old 7th Dec 2017, 9:30 pm   #49
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

I used a velleman handheld scope with a component tester attachment to measure the component values, really handy.

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http://www.velleman.co.uk/contents/e...HPS140MK2.html

http://www.velleman.co.uk/contents/e...HPS140Mk2.html
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Old 8th Dec 2017, 8:29 pm   #50
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

Quick question about capacitor values:

Some of the caps i cant purchase the exact values so i have a choice of two.

C4 - C6 is originally 0.25uf i can either have 0.22uf or 0.33uf @400v-630v

Most of them i can get exact values, for above do i go 0.22uf or 0.33uf?

Thanks
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Old 8th Dec 2017, 9:49 pm   #51
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

Quote:
Originally Posted by vishalk View Post
Quick question about capacitor values:

Some of the caps i cant purchase the exact values so i have a choice of two.

C4 - C6 is originally 0.25uf i can either have 0.22uf or 0.33uf @400v-630v

Most of them i can get exact values, for above do i go 0.22uf or 0.33uf?

Thanks
0.22uF is the nearest preferred value to the 0.25uF. Any working voltage above 350V is suitable, I'd go for 400 or more to give a bit of extra safety margin as the Ht will be around the 320 to 330V mark.

Now then, had you read your Spicer book "Firsts in high fidelity", You would have discovered for yourself the reasons for the circuit differences and the differences in the 3925 and 8778 transformers. I don't want to sound "preachy" but most of the info you need is in that book. Including the correct circuit diagrams.
I will also confirm with the rest of the good advice here for you not to get hung up on fancy resistors and capacitors. Use good quality standard plastic film capacitors for coupling. I have stated this in an earlier post, I did the expensive experiments for you so to speak! I used the standard 630V vishay polyester caps in my "new build" of the leak Tl25+ circuit and have never felt any need to "Upgrade" them. And I'm rather fussy about perceived sound quality.
Again, resistors, I use fairly mundane metal film 1% ones as they are as inexpensive as any other good resistor, I also agree with the suggested suppliers from other posters. I usually try RS online for my bits.
Again as others have observed, you are extremely unlikely to get British made components and in any case you'll never get original parts (that are serviceable). So do what HJL would almost certainly have done and use the best value decent quality and appropriate parts available on the market.

It's great news that your valves have tested good, there's a decent bit of money saved.

I hope I haven't put you off Vishalk and I do hope you get your stereo20 singing soon. I'm listening to mine as I type and very nice it is too.

Andy
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Old 9th Dec 2017, 5:57 pm   #52
vishalk
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

Quote:
0.22uF is the nearest preferred value to the 0.25uF. Any working voltage above 350V is suitable, I'd go for 400 or more to give a bit of extra safety margin as the Ht will be around the 320 to 330V mark.
I thought as much

Quote:
Now then, had you read your Spicer book "Firsts in high fidelity", You would have discovered for yourself the reasons for the circuit differences and the differences in the 3925 and 8778 transformers. I don't want to sound "preachy" but most of the info you need is in that book. Including the correct circuit diagrams.
I have been flicking through the book, actually i read about the transformers yesterday as i started reading it from the beginning, only got to chapter three so far!

Quote:
I will also confirm with the rest of the good advice here for you not to get hung up on fancy resistors and capacitors. Use good quality standard plastic film capacitors for coupling. I have stated this in an earlier post, I did the expensive experiments for you so to speak! I used the standard 630V vishay polyester caps in my "new build" of the leak Tl25+ circuit and have never felt any need to "Upgrade" them. And I'm rather fussy about perceived sound quality.
Been reading a great deal on capacitors and perceived sound differences between PIO and POLY types. Not going fancy on the components, they will be good quality though. I may buy some Russian K40Y-9 just to fill the space and try and keep the look. Aside from that, for myself the leak TL12's i'll be my testing amps for different components. One will be with commercial VISHAY/DALE parts, the other ill spend a little more on so called high end audio components and see if i hear a difference.

Quote:
Again, resistors, I use fairly mundane metal film 1% ones as they are as inexpensive as any other good resistor, I also agree with the suggested suppliers from other posters. I usually try RS online for my bits.
Again as others have observed, you are extremely unlikely to get British made components and in any case you'll never get original parts (that are serviceable). So do what HJL would almost certainly have done and use the best value decent quality and appropriate parts available on the market.
On it as we speak! Going to do HJL proud

Quote:
It's great news that your valves have tested good, there's a decent bit of money saved.
Saved some pennies that's for sure, means i can blow the savings on high end components (i'm kidding)

Quote:
I hope I haven't put you off Vishalk and I do hope you get your stereo20 singing soon. I'm listening to mine as I type and very nice it is too.
Not at all Andy it's all good and if most of the members are saying similar things then i will listen and take note. It will be singing and put back to perfect condition i can assure you! Thanks
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Old 9th Dec 2017, 6:14 pm   #53
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

Best sounding resistors what?? Load of rubbish me thinks. These were built with mainly standard resistors and sound just fine.

BVWS parts excellent quality.
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Old 10th Dec 2017, 10:58 pm   #54
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

All good passive compoments (i.e., resistors, capacitors and inductors) will sound the same. They are all trying to get as near as possible to an ideal model of the components -- and it's a fundamental principle of mathematics that if A=B and A=C, then B=C.
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Old 12th Dec 2017, 2:56 pm   #55
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

I ordered different brands of resistors from Farnell electronics which arrived today.

These are all 2W 5% tolerance resistors, the blue ones are MULTICOMP, the pale coloured resistors are TECONNECTIVITY and the smaller ones are VISHAY.

I wanted to see which ones were big and small so I could choose the right look for the amp.
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Old 12th Dec 2017, 3:08 pm   #56
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

Could you not have just read the specs which would have given the sizes?
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Old 12th Dec 2017, 3:46 pm   #57
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

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Could you not have just read the specs which would have given the sizes?
I did, but I visually had to see what they look like and choose what I like, I prefer to have things in front of me.

I know a resistor is a resistor but it's good to see whats on offer.
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Old 12th Dec 2017, 3:52 pm   #58
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

The Vishay ones are rated at 500V, use them. When the amplifier is completed and working, no-one will see whats inside, so does it really matter!
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Old 12th Dec 2017, 4:33 pm   #59
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

Don't get too hung up on Audio-Karma......Just about every resistance and condenser component you put into that Leak today will be superior to the originals.
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Old 12th Dec 2017, 4:35 pm   #60
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Default Re: Leak Stereo 20 and TL12 Plus in need of recommissioning. Help and Guidance needed

As long as they are fitted neatly and correct rating,then that really is all that matters.
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