Author Topic: Leak Stereo 20 Modifications  (Read 24668 times)

Offline stevenvalve

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Re: Leak Stereo 20 Modifications
« Reply #40 on: November 14, 2014, 02:48:33 AM »
I have finally settled on the perfect choke for the full on leak 20. This is the one to get, UTC Special series PA 40. This amp just sounds so good.... to been fair, it's full of the best hand picked stuff so it should sound great, and it does.
« Last Edit: November 14, 2014, 03:03:24 AM by stevenvalve »

Offline stevenvalve

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Re: Leak Stereo 20 Modifications
« Reply #41 on: November 14, 2014, 03:47:09 PM »
There are plenty of great vintage chokes out there for the leak, or any audio application, UTC generally make great sounding vintage chokes, with this brand its hard to go wrong. This model just works well with the leak. I have no doubt they make others that will work even better, i can only try what i have.

Offline stevenvalve

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Re: Leak Stereo 20 Modifications
« Reply #42 on: November 14, 2014, 04:58:28 PM »
I have been modifying the standard Leak stereo 20, I wanted it to sound good on the cheap, First i fitted 4 Hovland .47 music caps, early one's, then 4-1W Shinkoh resistors 10K. Tonight i dropped in 2 Jensen electrolytic, one dual 100Uf to replace to cap nearest the transformers and one dual 47UF down the other end. That improved the sound dramatically. It now sounds really good.
  The Leak Stereo 20. Standard this amp was OK sounding, But this exercise shows with just a few well chosen mods and valves, it can be just superb. I have been running this amp all day, It's sounding, just great. The cheaper valves i have chosen for this amp, 1 long plate 12AU7 mullard-1959 in the critical first position, 2 mullard 12AX7 short plates-1960s, 4 Australian EL84s, mullard GZ34. The Leak Stereo 20 is cheap to buy, cheap to modify, and cheap to retube, Most people will never need another amp. For the interested I put a pointer to show where the one watt 10K shinkoh resistors are install.
« Last Edit: November 14, 2014, 08:21:52 PM by stevenvalve »

Offline kajak12

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Re: Leak Stereo 20 Modifications
« Reply #43 on: November 14, 2014, 09:28:30 PM »
I have been modifying the standard Leak stereo 20, I wanted it to sound good on the cheap, First i fitted 4 Hovland .47 music caps, early one's, then 4-1W Shinkoh resistors 10K. Tonight i dropped in 2 Jensen electrolytic, one dual 100Uf to replace to cap nearest the transformers and one dual 47UF down the other end. That improved the sound dramatically. It now sounds really good.
is that for me?
still discovering the link between electronics and audio reproduction.so much to learn and so little time

Offline klackto

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Re: Leak Stereo 20 Modifications
« Reply #44 on: January 12, 2015, 01:16:13 AM »
Been doing some work on my Stereo 20.
Had fitted  choke previously and also recently changed output valve cathode resistor bypass caps to 30uf Solen PB mounted along 1 side.
Did some more work today nd put in 47uf Jensens for the driver cathode resistor bypasses.
I previously had a combination of Auricap and  Hovland coupling caps such in theory should have worked well in combination but somehow it wasn't quite doing it for me.
The amp lacked the musicality it had when I had Jensen copper foils which were bloody unreliable.
I had some 0.47uf copper foil Ampohm caps that were bought for a project that never eventuated
and ordered some 0.1uf Ampohm tin foils for the driver stage.
I know I committed the cardinal sin of making more than one change at a time, but hey, patience was not always my forte.

Offline stevenvalve

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Re: Leak Stereo 20 Modifications
« Reply #45 on: January 12, 2015, 07:00:05 PM »
Been doing some work on my Stereo 20.
Had fitted  choke previously and also recently changed output valve cathode resistor bypass caps to 30uf Solen PB mounted along 1 side.
Did some more work today nd put in 47uf Jensens for the driver cathode resistor bypasses.
I previously had a combination of Auricap and  Hovland coupling caps such in theory should have worked well in combination but somehow it wasn't quite doing it for me.
The amp lacked the musicality it had when I had Jensen copper foils which were bloody unreliable.
I had some 0.47uf copper foil Ampohm caps that were bought for a project that never eventuated
and ordered some 0.1uf Ampohm tin foils for the driver stage.
I know I committed the cardinal sin of making more than one change at a time, but hey, patience was not always my forte.
Love that line (patience was not always my forte) I think its always been a problem for most audiophiles. Interesting combination, how does the amp sound now.

Offline klackto

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Re: Leak Stereo 20 Modifications
« Reply #46 on: January 19, 2015, 12:32:41 AM »
Finally had a chance to have a decent listen yesterday. Early days but the easiest way to describe the change is that the "inner glow" of music is portrayed more effectively. I had previously had a mod done to the feedback circuit in an attempt to reduce gain but have now returned it to stock.
I'm using the Leak in a second system in a spare bedroom using speakers I knocked up a while back using bamboo ply and diatone clone drivers from eBay.

Offline klackto

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Re: Leak Stereo 20 Modifications
« Reply #47 on: January 19, 2015, 12:39:53 AM »
Here's a pic of the speakers.

Offline stevenvalve

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Re: Leak Stereo 20 Modifications
« Reply #48 on: January 19, 2015, 01:49:32 AM »
I have my second Leak Stereo 20 in my bedroom with the 47 Lab lens speakers. I need good bass and weight with these small fullrange drivers, so i have the speakers right up against the wall,  the sound is just superb

Offline Jehuty

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Re: Leak Stereo 20 Modifications
« Reply #49 on: February 11, 2015, 11:02:52 AM »
You have too many Leak amps. Are they really that good? Or is it just a myth? http://www.stereo.net.au/forums/index.php?/topic/78049-the-myth-of-leak-amplifiers/

 :P
Not all that matters can be measured, not all that can be measured matters.

Offline kajak12

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Re: Leak Stereo 20 Modifications
« Reply #50 on: February 13, 2015, 09:31:37 PM »
You have too many Leak amps. Are they really that good? Or is it just a myth? http://www.stereo.net.au/forums/index.php?/topic/78049-the-myth-of-leak-amplifiers/

 :P
Trust STEVEM to start the thread lol  :P :P :P :P
still discovering the link between electronics and audio reproduction.so much to learn and so little time

Offline klackto

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Re: Leak Stereo 20 Modifications
« Reply #51 on: April 04, 2015, 12:23:31 PM »
We were up in the mountains for a weekend in January and I managed to take the time to visit Steven.
Big thanks to Steven and his wife and had a very enjoyable evening catching up and enjoying some great music and fine sound.
While I was there we tried my modified Leak Steven's Quads and while it was pretty good, Steven spotted a potential (no pun intended) problem with a couple of the Ampohm cans possibly shorting against some resistors.
So next day I fire up the soldering iron and reposition the caps so as to give more clearance to the board and when I fire it up there's a high frequency howl on one channel .......... wtf :o ?????
So fast forward a couple of days and find out my brother in Melbourne had a stroke so the whole audio thing was put on hold for a while.
He's now staying us while he is recuperating and yesterday thanks to the rain, I managed to have another look at the stereo 20.
The solens I had fitted for the el84 cathode resistor bypass were supported by stick on pads and cable ties.
Probably due to the amp being moved around one of the caps was loose and had pressed on the 1k resistor to the driver tube and one leg had come away.
I desoldered the resistor and had some 10mm angle aluminium I had bought a while ago as I was never comfortable with those stick on pads and spent a couple of hours attaching the solens much more securely and thankfully all seems well with the Leak again : :)
Hope to make another trip up to the mountains soon.

Offline klackto

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Re: Leak Stereo 20 Modifications
« Reply #52 on: April 04, 2015, 07:10:25 PM »
Meant resoldered the resistor .... not desoldered.

Offline stevenvalve

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Re: Leak Stereo 20 Modifications
« Reply #53 on: April 07, 2015, 09:00:59 PM »
Picked up 4-Jupiter Copper Foil 0.47uF 600VDC. I will remove the 4-Duelund Copper Foil 0.47uF VSF from the leak stereo 20, I will give them a good run in, lets see how good they are.

Offline stevenvalve

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Re: Leak Stereo 20 Modifications
« Reply #54 on: April 23, 2015, 06:25:37 PM »
Just replaced the 4-Duelund Copper Foil 0.47uF VSF with the 4-Jupiter Copper Foil 0.47uF 600VDC. I ran flying leads so I can try both ends of the caps for best sound, plus easily changing back to other capacitors for evaluation. The amp is running as i type.

Offline Rob181

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Re: Leak Stereo 20 Modifications
« Reply #55 on: April 25, 2015, 09:24:44 AM »
Looking forward to hearing your thoughts...Dueland Vs Jupiter...

Offline stevenvalve

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Re: Leak Stereo 20 Modifications
« Reply #56 on: May 04, 2015, 07:50:47 PM »
I have been running in the 4-Jupiter Copper Foil 0.47uF 600VDC capacitors for about a week now, the impression is very good despite the use of silver lead-in and lead-out wires being used on the caps. Can I hear the silver, yes it's particularly obvious in the high frequency's, there is a slight white lean metallic sheen typical of silver, I have been told these caps need a long run in and to expect a marked change, so I will do that before any major comment.  Have they reached 4-Duelund Copper Foil 0.47uF VSF territory, no not yet, but already they outperform them in Clarity and detail, they are particularly good in understanding diction.   
« Last Edit: May 04, 2015, 07:55:09 PM by stevenvalve »

Offline rab

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Re: Leak Stereo 20 Modifications
« Reply #57 on: May 15, 2015, 10:45:56 PM »
Thanks Steven, that's very interesting; might have to try some.

Incidentally, here's a blog post of only 1 week ago describing the restoration of a Leak TL10.1:
http://truefi.blogspot.com.au/2015/05/vintage-treasuries-restauration-of-leak.html

- r

Offline ozmillsy

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Re: Leak Stereo 20 Modifications
« Reply #58 on: May 22, 2015, 06:23:44 PM »
I have been running in the 4-Jupiter Copper Foil 0.47uF 600VDC capacitors for about a week now, the impression is very good despite the use of silver lead-in and lead-out wires being used on the caps. Can I hear the silver, yes it's particularly obvious in the high frequency's, there is a slight white lean metallic sheen typical of silver, I have been told these caps need a long run in and to expect a marked change, so I will do that before any major comment.  Have they reached 4-Duelund Copper Foil 0.47uF VSF territory, no not yet, but already they outperform them in Clarity and detail, they are particularly good in understanding diction.

Hey Steven,  I was browsing around the Soniccraft website, looking for thicker gauge jupiter wire,,  and I noticed these (copper leads, paper in beeswax),,,,,

http://www.soniccraft.com/product_info.php/jupiter-vintage-cu-lead-047uf-600vdc-p-4516

Quote
The sound is extremely warm and rich with perhaps a bit more detail than many PIOs.

The price looks reasonable enough to try.  Pity they are not in production anymore.
It's all about the music,, not the equipment.

Offline stevenvalve

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Re: Leak Stereo 20 Modifications
« Reply #59 on: May 22, 2015, 08:59:15 PM »
Well, I have had a good listen to the 4-Jupiter Copper Foil 0.47uF 600VDC capacitors, Just put back the  4-Duelund Copper Foil 0.47uF VSF, Thoughts on the Jupiter Copper Foil 0.47uF capacitors soon. Being a little crazy I have removed the UTC choke and tried some Duelund 50R resistors in it's place, I had to put two in series to get the 100R value, as i type they sound promising,   
« Last Edit: July 05, 2015, 02:53:55 PM by stevenvalve »