LEAK st20
- Thread starter Fitnessed
- Start date
Jobs left to do......
Voltage selectors and impedance ,clean and insert solid copper core soldered in.
When i checked the windings there was a difference between the two st20 i have.
I then transferred the modded selectors over and all was good.
X4 input metal film resistors.
91k value to be made up with parallel resistors.
uf4007 diode mod.
fuse holder for drop resistor location.
Need to look at power up methods,variac,dim bulb,dummy load and measurements.
Have known good valves...
Voltage selectors and impedance ,clean and insert solid copper core soldered in.
When i checked the windings there was a difference between the two st20 i have.
I then transferred the modded selectors over and all was good.
X4 input metal film resistors.
91k value to be made up with parallel resistors.
uf4007 diode mod.
fuse holder for drop resistor location.
Need to look at power up methods,variac,dim bulb,dummy load and measurements.
Have known good valves...
Watching your progress with interest as Ive got a st20 I want to fire up again sometime.
If you dont mind me asking , what is the uf4007 mod and the fuse holder for drop resistor location ?
I plan to power mine up slowly via my variac, probably first up to something like 50% with dummy load while
monitoring voltages ?
Good find about the voltage and impedance selectors. I'll have a good look at mine now.
If you dont mind me asking , what is the uf4007 mod and the fuse holder for drop resistor location ?
I plan to power mine up slowly via my variac, probably first up to something like 50% with dummy load while
monitoring voltages ?
Good find about the voltage and impedance selectors. I'll have a good look at mine now.
diode mod and more
https://pinkfishmedia.net/forum/threads/leak-stereo-20.113461/page-28Rs part number for diodes -671-5740
IMG_6037 - Copy by vintage audio vintage audio, on FlickrIt appears that my st20 originally ran a stepped network on r5.
A bit of digging reveals that is was something added to later grey st20s.
It does not show on circuit diagrams.
Snowman al(R.I.P) highlighted this on the uk vintage radio and restoration forum.
Anyone have any thoughts on this? worth reinstating?
Fully populated…
Close up of diode mod and radford revival fuse/resistor set up.
Powered up on a variac with a dummy load,voltages verified.
Then ran on sacrificial speakers for an hour.
No smoke and no fuses hurt
Switched over to impulse Lali,first time I have tried a valve amp with these.
As expected marvellous!
A lot of effort has gone into not altering the original wire persons work.
All the original components are packed safely. All original phono and speaker outputs.
Mods - fuse, diode mod uf4007.
50+50 caps x2.
A large thank you to Will at Radford Revival.
Close up of diode mod and radford revival fuse/resistor set up.
Powered up on a variac with a dummy load,voltages verified.
Then ran on sacrificial speakers for an hour.
No smoke and no fuses hurt
Switched over to impulse Lali,first time I have tried a valve amp with these.
As expected marvellous!
A lot of effort has gone into not altering the original wire persons work.
All the original components are packed safely. All original phono and speaker outputs.
Mods - fuse, diode mod uf4007.
50+50 caps x2.
A large thank you to Will at Radford Revival.
Mike Hughes
pfm Member
Seriously gorgeous amp.
That looks very neat, you should be very satisfied with your work.
I've done the fuse mod too and moved the 'hot' resistor following Will's lead. I didn't do the diode addition but I did buy them so I will install them at some point. Might do it this weekend if the weather is bad ........... and in between the football.....
I've done the fuse mod too and moved the 'hot' resistor following Will's lead. I didn't do the diode addition but I did buy them so I will install them at some point. Might do it this weekend if the weather is bad ........... and in between the football.....
Radford Revival
Trade: Radford Revival
Great work!
Rosewind
Lost in Translation
Looks spick-sparkling new! Congratulations! Well done!
The tatty one, I stupidly sold to Mike P. Then again, I thought I needed the money for ... I simply can't remember. Well, I am after one that works and looks half as good as this one. I will have to save for a bit. Otherwise I only need a Moerch UP4 12" as arm number 2 to go with the pristine Moerch tuntable I bought last year - see avatar (a DP6 12" will also do nicely) and an SPU #1S. Then I am set. Well, perhaps another subwoofer to go with the Lowther London horn speakers would not go amiss.
The tatty one, I stupidly sold to Mike P. Then again, I thought I needed the money for ... I simply can't remember. Well, I am after one that works and looks half as good as this one. I will have to save for a bit. Otherwise I only need a Moerch UP4 12" as arm number 2 to go with the pristine Moerch tuntable I bought last year - see avatar (a DP6 12" will also do nicely) and an SPU #1S. Then I am set. Well, perhaps another subwoofer to go with the Lowther London horn speakers would not go amiss.
I am considering selling my ST20, which is a Mike P rebuilt beauty and sounds stunning. Mine is the first one in this thread. PM if that is of interest.
Another Leak Stereo 20 restoration
I appreciate that there have already been several Leak Stereo 20 restoration threads here but here I go again with another one. This is my fourth Stereo 20 restoration and by far the most in-depth restoration so far. I bought this particular example from @Rosewind a few years ago and it has...
pinkfishmedia.net
Edit: I've just realised this is your actual amp you previously owned! Now fully singing, looking truly beautiful, and sounding amazing!!
Rosewind
Lost in Translation
What a coincidence.
I thought my tatty example sounded fine with my Quad ESL 57s. I already had an EAR 516 playing through them so sold it on.
I am not yet ready for another Leak ST20 as I also have two other valve amps in my house - see signature. One of those would need to go as I don't want anything here that doesn't get any use.
I thought my tatty example sounded fine with my Quad ESL 57s. I already had an EAR 516 playing through them so sold it on.
I am not yet ready for another Leak ST20 as I also have two other valve amps in my house - see signature. One of those would need to go as I don't want anything here that doesn't get any use.
Its worth doing, know of someone with a JJ GZ34 that has recently flashed over and took some capacitors out..
chiily
PFM Special Builder
I've not had a GZ34 flash over, but I do add that diode mod just in case something like that happens.
Do you know how old the JJ GZ34 was? Just thinking that a few years ago JJ had a poor build quality reputation. It does appear to be much improved now from my experiences with JJ EL34s (new quad in my Radford STA15 and they sound amazing, dare I say better than the ST20 into Egro IXs, thinking of selling the Leak on).