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Ping Mike Samra. Re strapping my LEAK St20s to mono

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Posted on July 19, 2017 at 21:40:07
Timbo in Oz
Audiophile

Posts: 23221
Location: Canberra - in the ACT - SE Australia
Joined: January 30, 2002
 Hi Mike, I've had some negatives about lots of heat and distortion on some stereo chassis tube amps, when strapped!?

That is 'it might work, but it might have' the above result, and damage the amplifier / s.

Soo, would you be willing to strap your St20 and run it into laboratory loads of 2 ohms or 4 ohms PLUS enough UF to mimic 'stats for both the 2 and 4 ohms loads?

Another week or two and phase 1 with bass speakers going down to 30 / 35Hz & analogue Eq for each bass spkr, will be running soon, and one sub woofer. 4 subs will be phase2.

The wiring was / is not simple, but I've got the modelling done at last.



Warmest

Tim Bailey

Skeptical Measurer & Audio Scrounger


 

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RE: Ping Mike Samra. Re strapping my LEAK St20s to mono, posted on July 22, 2017 at 09:05:02
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 Tim'
You lose some overall depth when you strap amps in parallel.I'm not sure you will gain a lot with ST20s but you can strap them. Just make sire the impedances are the same.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: Ping Mike Samra. Re strapping my LEAK St20s to mono, posted on July 23, 2017 at 10:46:03
PakProtector
Audiophile

Posts: 12363
Joined: May 14, 2002
 So bridge them then...:) 8R load across each of the 4R taps. You will need to feed the amps a balanced signal( like what you'd get out of a phase splitter ).
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

 

On further reflection I will run just one stereo chassis., posted on July 24, 2017 at 00:36:49
Timbo in Oz
Audiophile

Posts: 23221
Location: Canberra - in the ACT - SE Australia
Joined: January 30, 2002
 Even without a 1st order HP filter @ 150Hz, many people find 20 watts of PP valve power sufficient for a QUAD 63.

See below for the mods done in the 1990s to both of these LEAK stereo amps. Both now have 4 x 470Uf filter caps, bypassed. The first two caps are in parallel, IIRC.

Less NFB, yet with lower distortion, quieter, more power, and far better bass.










Warmest

Tim Bailey

Skeptical Measurer & Audio Scrounger


 

RE: On further reflection I will run just one stereo chassis., posted on July 26, 2017 at 17:54:58
PakProtector
Audiophile

Posts: 12363
Joined: May 14, 2002
 You can do phase splitting with a transformer too. The UTC A-18 is quite fine, and will swing a remarkable voltage across its secondary at 18-20 cps.
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

 

Thanks for that. , posted on July 26, 2017 at 18:23:42
Timbo in Oz
Audiophile

Posts: 23221
Location: Canberra - in the ACT - SE Australia
Joined: January 30, 2002
 I will still try the single St20. As I pointed at in this thread each Chassis can now deliver 20W RMS pc. And they have 1st order HP PLL input filters on them, so 20WPC just may be enough

IF it's not. Not loud enough cf the Fostex, I will decide if I prefer the Valve sound anyway and then go with balanced drive.

More money! Sighhh!

And IF I prefer the valve sound over the Fostex it's going to get pooged / blue-printed.

? We have very hot Summers, and valve amps are then at risk.

Even more $$$$!

IF it's the Fostex I prefer, then I may well sell the LEAKs.

-------------------------------------------------------------

JBTWay - Your quote re a 'Quaker' is a favourite of mine. Even though I'm not an American, and not a gun rights type, either.


Warmest

Tim Bailey

Skeptical Measurer & Audio Scrounger


 

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