M-65 Mono Blocks

by TMadden Thu Nov 20, 2014 5:21 pm

TMadden: Posts : 99
Join date : 2011-12-22

Post n°1

M-65 Mono Blocks

by TMadden Thu Nov 20, 2014 5:21 pm

Hey Everybody,

I wanted to share my latest amp project, the VTA M-65 mono blocks. I really like the sound of the ST-120, but I wanted to add a little twist of my own, so I decided to duplicate the ST-120 but in mono-block form. Luckily Roy has just introduced the MK 3 driver board which is identical to the ST-70-120 driver board but for mono amps, and about the same time a set of used M-125 chassis became available. So, I ordered the ST-120 transformers from Bob and got to work! The sound is the same as I love about the ST-120's, very open and transparent, and they are able to reproduce a 1KHz square wave perfectly, no tilt, ringing or overshoot, just like the ST-120. The power supplies are now of course hardly loaded, which can't hurt the sound either. They sound awesome in my home theater system!

Last edited by TMadden on Thu Nov 20, 2014 5:35 pm; edited 1 time in total (Reason for editing : typo)

by **Bob Latino** Thu Nov 20, 2014 5:32 pm

Bob Latino

Bob Latino: Admin; Posts : 3273
Join date : 2008-11-26
Location : Massachusetts

Post n°2

Re: M-65 Mono Blocks

by Bob Latino Thu Nov 20, 2014 5:32 pm

Nice work Troy .. Just a minor correction. You are using the VTA M-125 POWER transformers but with the VTA ST-120 OUTPUT transformers. Sort of like the Dynaco Mark IV's monoblocks that each used one Dynaco ST-70 A-470 output transformer.

Bob

by TMadden Thu Nov 20, 2014 5:35 pm

TMadden

TMadden: Posts : 99
Join date : 2011-12-22

Post n°3

Re: M-65 Mono Blocks

by TMadden Thu Nov 20, 2014 5:35 pm

Yes, I just saw my typo, I'll correct that, thanks Bob!

by sKiZo Thu Nov 20, 2014 5:41 pm

sKiZo

sKiZo: Posts : 1530
Join date : 2013-04-01
Location : Michigan USA

Post n°4

Re: M-65 Mono Blocks

by sKiZo Thu Nov 20, 2014 5:41 pm

Be interested in hearing whether isolating the PTs had any effect on separation and sound stage ...

(Is the flipper in front of the output transformer for P/T switching?)

Nice work ... maybe Bob & Co will name it after you when they go into production ... clown

by TMadden Thu Nov 20, 2014 6:26 pm

TMadden

TMadden: Posts : 99
Join date : 2011-12-22

Post n°5

Re: M-65 Mono Blocks

by TMadden Thu Nov 20, 2014 6:26 pm

Sure, the separate power supplies should eliminate any cross-talk, and it gives the rectifier tubes a break too!
The sound-stage is immersive and very realistic, I'm pretty happy with the results!
The switch was the triode/ pentode switch, I'm not using it, I generally prefer pentode mode.