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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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6th Jun 2019, 10:36 am | #1 |
Tetrode
Join Date: Aug 2016
Location: Bedford, Beds. UK.
Posts: 59
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Leak Stereo 20 with Point One and Trough-Line 2 help.
Hi. I've just purchased excellent examples of these three. As I'm new to Leak equipment I'd really appreciate any advice on what valves work best etc and maybe I should include photos in case it needs a service? It works as it should so im assuming the caps are new...Its been used regularly not stored but the owner died and I've no history now...Also the trough line II has volume so assume it's a stand alone unit? Thanks
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6th Jun 2019, 11:24 am | #2 |
Rest in Peace
Join Date: Sep 2008
Location: Solihull, West Midlands, UK.
Posts: 4,872
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
I think you will find that Leak equipment was designed to use ordinary valves, that simply meet the spec for that valve. Hence there is no need to seek particular valve brands. Simply replace any which are faulty.
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6th Jun 2019, 11:27 am | #3 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
Posts: 8,327
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
The valves that will work best are the valves it was designed to use.....
Not quite sure how we can specifically advise you right now? Photos would help, especially of the internals to see what component changes may have been made.
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6th Jun 2019, 11:57 am | #4 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,863
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
There are four capacitors in that stereo 20, two in the point-one, which, if they go leaky risk damaging your output transformers and mains transformer, as well as taking out EL84s.
Just thinking they must be new because the amplifier sounds OK might not be as safe an assumption as you might later wish it had been. Standard advice is to check. Those transformers are essentially irreplaceable.... would you have bought one which was said to have a rewound transformer in it? Contrary to all the audio magazines and websites, capacitors don't have individual sounds. If one creates an audible difference then it's a sure indication that something somewhere is badly wrong. Leak was a manufacturer, and he did his designs carefully and did all the tolerancing maths. It would upset his profitability if his production line needed to select valves. It would upset his reputation if not all his amplifiers met their specs. So he did it right and any valve which meets the specification for its type should result in the full performance from the amplifier. This is good engineering at work. David
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6th Jun 2019, 1:01 pm | #5 |
Tetrode
Join Date: Aug 2016
Location: Bedford, Beds. UK.
Posts: 59
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Yes I agree hence my suggestion to show photos which should reveal if caps are replaced etc. That's good about valves. I know my Quad II's sound better with NOS British valves. Not impressed with Chinese or Russian equivalents.
The leak has Mullards. Will post pics soon. Thanks... |
10th Jun 2019, 9:11 pm | #6 |
Tetrode
Join Date: Aug 2016
Location: Bedford, Beds. UK.
Posts: 59
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Ok so here's some photos. Looks like it's had some work so hopefully a good job? I haven't cleaned it yet not that it needs more than a wipe and polish really. To show you the innards of point one and Troughline II. I'm assuming I just need to remove the top cover of each unit? Also does the Troughline II have a volume control for a variable output control? I've not seen a volume control on any other stand alone tuner before.
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10th Jun 2019, 9:24 pm | #7 |
Tetrode
Join Date: Aug 2016
Location: Bedford, Beds. UK.
Posts: 59
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Couple of close ups in the hope you can see more...
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10th Jun 2019, 10:48 pm | #8 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,567
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Looks like he's used 'Audiophile' caps. It's a neat job and should work well. It looks like it's had a new set of valves as well.....if those are ECC83's they are not a Mullard design....internal construction is completely different. Most of the audiophile valves are Sovtek (Russian) or 'Golden Dragon' (Chinese). Don't know how good they are.
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10th Jun 2019, 11:07 pm | #9 |
Tetrode
Join Date: Aug 2016
Location: Bedford, Beds. UK.
Posts: 59
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
I'm unsure how to react to a completely different layout. Ive no idea who did the work. The 83's are Marshall and the 84's say CCCP so early Soviet valves.The last one is a Mullard. I saw that Mullard and M on others in poor light so assumed all Mullard.
I had better check the other units too and post pics soon. They do work well together so I've no complaints especially if it looks safe to use. |
11th Jun 2019, 12:22 am | #10 | |
Dekatron
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,311
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Quote:
... in time a number of TL/12 Plus and Stereo 20 amplifiers were being returned to Leak with output stages that had 'burnt up' ... George Cooksey of Mullard suggested that the EL84 valves were being operated beyond the maximum rated voltage and maximum grid resistance. This practice can lead to thermal run-away ... The amps had to be redesigned and in the end a compromise was found which delivered (just about) 0.1% distortion and (not quite, but nearly) 12W output with the EL84s (just) inside their safe operating area. I would recommend against running with just any old valves though. Fortunately the Russians have developed a more robust version of the EL84 - the 6П14П https://www.radiomuseum.org/tubes/tube_6p14p.html. These, especially the -EV variants I believe, should be a very safe bet. The Marshall 'ECC83s' are, I think, Chinese 6N4s. They seem pretty robust too, although they're not running so close to the edge as the EL84s. The Stereo 20 is an unusually sensitive amp and this can make it prone to noise. You might find that if you swap the ECC83s around there will be one or two arrangements which generate less background noise than the others. These will be the ones with the quietest ECC83 in the first position (right alongside the input sockets). Cheers, GJ
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11th Jun 2019, 12:24 am | #11 |
Octode
Join Date: Nov 2013
Location: Penrith, Cumbria, UK
Posts: 1,993
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Those capacitors are Russian K40Y jobs. They are Paper in oil but have a glass seal on the lead outs, I think they may have been a Military specification. I used them on my Stereo20, but as to whether they were any different to a decent set of film capacitors is debateable.
As to Valves, Mullard and much other NOS are just too expensive to justify in my opinion, and as the the rest, there's only a handful of manufacturers left so really I'd just go for the best deal on a particular nationality. The Chinese stuff is cheap and I think as good as anything out there. The ECC83's should pretty much last well, the EL84s might be worth a check, the cathode voltages are as good a guide as any. A. |
11th Jun 2019, 9:00 am | #12 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
I've always been nervous of EL84s. I never built anything using them. All that internal staining put me off. Something undesirable had to be happening in there. That material had to be coming from somewhere, so I stuck to the good old 6V6 and 6L6 which seemed to be much longer lived. The staining in EL84s is something I associate with TV line output valves... things which are run hard and for long hours.
I didn't realise Leak was running them over their voltage ratings. They are definitely not suitable for ICAS. David
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11th Jun 2019, 9:25 am | #13 |
Tetrode
Join Date: Aug 2016
Location: Bedford, Beds. UK.
Posts: 59
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
I must say the set runs silent in operation and through speakers. That's why I purchased them really and the fact I've always wanted a nice condition Stereo 20 because it was first released a month after I was born so very special. I can't find a serial number anywhere. Is this an early model? Very happy with performance. Does anyone have advice on best speaker pairing? Ive got Castle Conway II and III. Spendor for BC1. RCL The little speaker. To name just a few (I should open a shop!).
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11th Jun 2019, 11:11 am | #14 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
When working on GPO kit, I remember performing tolerancing calculations to make sure everything would stay working with the worst likely tolerance combination.
The Stereo 20 uses the Mullard 5-10 design with 300V anode voltage and independent 270 ohms cathode bias for each valve but the design is based on nominal values and has very little contingency for tolerancing. In itself, the EL84 seems to be specified close to failure, perhaps due to greater manufacturing consistency in later valves, and I suspect the earlier octal valves did not cut it so fine. Most amplifiers of the period use the Mullard datasheet biasing recommendations as I guess this gave them the security that they could pass blame onto Mullard. We don't have the luxury of being able to return kit that's blown up, so I tend to check the anode volts and dissipation and make component adjustments to keep it comfortably within the limits. I have even bought some cheap Chinese voltage displays for my Avantic 5-20's so I can constantly monitor the cathode voltage. |
11th Jun 2019, 4:52 pm | #15 | |
Octode
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Quote:
Have a look at the output transformers, there will be a number on it (under the loom?). If it is 8778 it is the later type. The earlier ones are 3921. Yours does have the later mains transformer, it has an extra post for the neutral blue wire (next right of the 'Switch' connections.) Difficult to see the colours in the pictures, but the other later (or brought up to date) things to look for are 470K ohm grid resistors on the EL84s (R12 and R13) and 47k anode load resistors on the first ECC83 (R5). I've added a .pdf of the circuit and parts location for info at the end. No worries re the EL84s, those Russian ones are well within their working range in the ST20. It looks very well renovated with a nice choice if components and nicely done too. Enjoy it. Alan
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11th Jun 2019, 8:54 pm | #16 | ||
Tetrode
Join Date: Aug 2016
Location: Bedford, Beds. UK.
Posts: 59
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Quote:
Shall I make another post 're. Speaker matching as it makes sense to try to match with best sounding speakers others have already experimented with so it drives them easily. Set up at 8 ohms currently. The previous owner used KEF Cantor II's which i was given just in case. I tested it with these and it seemed to drive them well. Loud at about 1/4 turn. |
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11th Jun 2019, 9:44 pm | #17 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Speaker matching?
Several of us have heard most of those speakers, but none of us have heard your room. So you're on your own. Any advice will be of very limited applicability. Use your own ears, because they are what it's all about. You don''t have to settle on one pair. Change them around from time to time and enjoy the change. We also don't know your choice in music or how loud you prefer to listen. But the room trumps it all. David
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11th Jun 2019, 10:47 pm | #18 |
Tetrode
Join Date: Aug 2016
Location: Bedford, Beds. UK.
Posts: 59
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Sorry thought I'd made it clear.. I'm talking about matching regarding easily driven etc. not audibly as we all hear differently let alone room acoustics and the source used etc.
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11th Jun 2019, 11:25 pm | #19 | |
Octode
Join Date: Nov 2013
Location: Penrith, Cumbria, UK
Posts: 1,993
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Quote:
Don't get hung up on "suitability", these things are more durable than a lot of folk would have you think. If you like whats on the end of them that's it really. As to reliability of EL84s, I have no qualms about them and they will last a long time especially as your later version runs them well inside their parameters. My S20 is giving sterling service still using a set of Chinese Golden Dragon Branded valves, they are probably the standard Shuguang jobs as golden Dragon is a Brand name used by a UK supplier. I have tried the Russian 6P14PEV types, they were Edicron branded re-marked and they were fine but weren't as robust as the standard Chinese ones. I may have been unlucky. A. |
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12th Jun 2019, 8:43 pm | #20 |
Tetrode
Join Date: Aug 2016
Location: Bedford, Beds. UK.
Posts: 59
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Re: Leak Stereo 20 with Point One and Trough-Line 2 help.
Here are some photos of the Point One and Troughline II. As you all can probably guess I'm no electronics engineer I work on electrical appliances that need simple diagnosis and replacement of pcb's not repair them. The inside of these two look to be original or not serviced for some time? Thanks for all your help. Much appreciated by the way....
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