How Do I Monoblock These Leak TL/25 Plus Amps? (2024)

I'd like to bring up these TL/25 Plus amps and Point One Stereo preamp slowly on a variac and see if there are any issues, but as I've never monoblocked any gear before (and the Leak pairing of the amps with the preamp seems funky), I'm feeling a little lost.

The deal came with some cables, but it appears the 3-pin mains power cables for the amp(s) are missing (I'm assuming both amps need to be connected to mains, though I'm not 100% sure....) In the cable pic below, the female 2-pin plug shown in the pic was later attached to the "switch cable" coming out of the LEFT amp. The RCA to RCA cable was just thrown in and will be discarded...

(NOTE: I know the Pilot SP-210 preamp I have was designed to be powered from the umbilical of the SA-232 amp—which is connected to mains—so I'm thinking that the Leak preamp is similar?)

Possible Connections (see pic for visual):

1. Mains cable with 3-pin female socket (missing) into LEFT AMP male "A.C Power" 3-pin socket
2. Mains cable with 3-pin female socket (missing) into RIGHT AMP male "A.C Power" 3-pin socket
   
3. Bulgin cable male plug end inserted into LEFT AMP "Preamp" socket
4. Bulgin cable female plug end inserted into PREAMP "From Amplifier" male socket
   
5. LEFT AMP "Switch Cable" with 2-pin female plug end inserted into PREAMP 2-pin male "Switch" socket
   
6. RCA end of RCA/Bulgin cable inserted into PREAMP "Output R" RCA out
   
7. Male Bulgin plug end of RCA/Bulgin cable inserted into RIGHT AMP "Preamp" socket

If this is correct, I would need to track down two vintage 3-pin female Bulgin plugs and make new power cables for both the LEFT and RIGHT amps (assuming that the PREAMP is powered from the LEFT amp...)

Since the A.C. POWER socket appears to be grounded, should I use a 3-prong grounded wall plug?

If anyone has experience with this set-up (Leak monoblock amps paired with Leak preamp), or can lead me in the right direction in understanding how to correctly set this up for testing/use, it would much appreciated.

Thanks in advance!

You don't really need hours or days on a variac like I have seen some people do. The rectifier tube(s) needs something like a minimum of 80 volts before it will start to conduct. Besides, you can almost always tell if there is going to be a problem within the first few minutes or seconds after power up.

You can always take a meter to the can capacitors to check for any initial shorts.

Make sure they are fused and don't worry about it!

Dandy said:

You will need power connections to both amps, though the preamp is powered from just one, and use three prong grounded plugs.

Click to expand...

Thanks! Just the info I needed—now off to find the correct Bulgin plugs...

century tek said:

You don't really need hours or days on a variac like I have seen some people do. The rectifier tube(s) needs something like a minimum of 80 volts before it will start to conduct. Besides, you can almost always tell if there is going to be a problem within the first few minutes or seconds after power up.

You can always take a meter to the can capacitors to check for any initial shorts.

Make sure they are fused and don't worry about it!

Click to expand...

Thanks—I know it’s likely at least the coupling caps and other elytics will need to be replaced (I’ll need to watch for dc leakage), so the variac isn’t so much to “reform” the caps for long-term functioning, but rather just to get a sense of current condition.

If there isn't any hum, they are most likely okay for now. If you want to test them, just stay there with them and watch for anything abnormal (excess heat, smoke, hot smell warm can in minutes) and if you see something, just cut power, find the problem and fix it.

They are probably okay for now. Tube stuff is pretty rugged and can usually take a certain amount of abuse and over voltage events and survive. Solid state not so much.

Connect some speakers and you might be blown away.

century tek said:

If there isn't any hum, they are most likely okay for now. If you want to test them, just stay there with them and watch for anything abnormal (excess heat, smoke, hot smell warm can in minutes) and if you see something, just cut power, find the problem and fix it.

They are probably okay for now. Tube stuff is pretty rugged and can usually take a certain amount of abuse and over voltage events and survive. Solid state not so much.

Connect some speakers and you might be blown away.

Click to expand...

Need to first get some mains cords with Bulgin 3 prong AC plugs first. Seems like the only place is from the Ebay UK (made with US 3-prong and 2 meter cable...)

You can at least try one amp at a time as you have one of the power cords. Pretty much basic if you look underneath at the connections and then draw it out and make your own cord for the other amp.

EDIT: Oh wait, I see you don't have a power cord. Oh well, same goes as you can look underneath and see where the AC connections terminate into the power transformer and make temporary plugs for them out of regular lamp cord.