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New User from Arizona
Posted: July 10th, 2021, 6:36 pm
by gstitt
Hi,
I'm hooked on DIY, SET's and High Efficiency Speakers. Hoping to share thoughts with others similarly afflicted!
Greg
Re: New User from Arizona
Posted: July 10th, 2021, 9:35 pm
by SoundMods
gstitt wrote:Hi,
I'm hooked on DIY, SET's and High Efficiency Speakers. Hoping to share thoughts with others similarly afflicted!
Greg
Guilty as charged -- I think I will start an AA (Audiophiles Anonymous) group. I just have to figure out what the 12 steps to recovery would be. 
Re: New User from Arizona
Posted: July 11th, 2021, 7:43 am
by tomp
Welcome to the group. It must be interesting running SETs with the temperatures you are having now in Arizona. Hope things cool down for you soon.
Re: New User from Arizona
Posted: July 11th, 2021, 7:53 am
by DaveR
Welcome to the group.
Re: New User from Arizona
Posted: July 11th, 2021, 9:06 pm
by gstitt
DaveR wrote:Welcome to the group.
tomp wrote:Welcome to the group. It must be interesting running SETs with the temperatures you are having now in Arizona. Hope things cool down for you soon.
Thanks for the welcomes!
I run 3 watt 2A3 SET's, so it's almost manageable
Re: New User from Arizona
Posted: July 11th, 2021, 9:12 pm
by gstitt
SoundMods wrote:Guilty as charged -- I think I will start an AA (Audiophiles Anonymous) group. I just have to figure out what the 12 steps to recovery would be.
I had a pair of those big Cary SET's in a previous life. Wonderful sound in a smallish room using Sound Lab A3's! My current 2A3 SET's would be pretty intimidated!
Greg
Re: New User from Arizona
Posted: July 11th, 2021, 10:37 pm
by SoundMods
gstitt wrote:SoundMods wrote:Guilty as charged -- I think I will start an AA (Audiophiles Anonymous) group. I just have to figure out what the 12 steps to recovery would be.
I had a pair of those big Cary SET's in a previous life. Wonderful sound in a smallish room using Sound Lab A3's! My current 2A3 SET's would be pretty intimidated!
Greg
I got lucky and fell into a pair of CAD-805 Rev. 2 models and hot rodded them. I ended up using metal-plate (not graphite) 845s, JJ 300Bs, and G.E. 5691s.
They turned to be musical audio "microscopes." 
Re: New User from Arizona
Posted: July 12th, 2021, 4:44 pm
by Guy
Sorry, I've been traveling, away from the Internet.
Welcome to the club! I hope you find what you're seeking here.
Re: New User from Arizona
Posted: July 12th, 2021, 10:06 pm
by Grover Gardner
Welcome, new member! I'm in Oregon now, used to be in DC. It's a far-flung group these days.
Walt, do those Cary amps use feedback? I heard them once, many moons ago, at Audio Depot but I was so taken up with the Cary 300B amps in the front room I didn't know what I was listening to.
DC old-timers may have fond (or, not-so-fond) memoeries of that place. It was the first time I heard single-ended amps with ProAcs. Still have the ProAcs.
Re: New User from Arizona
Posted: July 13th, 2021, 8:07 am
by SoundMods
Grover Gardner wrote:Welcome, new member! I'm in Oregon now, used to be in DC. It's a far-flung group these days.
Walt, do those Cary amps use feedback? I heard them once, many moons ago, at Audio Depot but I was so taken up with the Cary 300B amps in the front room I didn't know what I was listening to.
DC old-timers may have fond (or, not-so-fond) memories of that place. It was the first time I heard single-ended amps with ProAcs. Still have the ProAcs.
The Carys have a feedback control that can be set for anything from 0 feedback to 10 db of feedback. The problem was that they fed the feedback from the 16-ohm transformer tap back to the first stage through a stranded Teflon hook-up wire laying down on the chassis and winding its way around other components to a pot and through a metal-film resistor to the cathode of the first tube (6SL7). With that arrangement -- it sounded better with no feedback. To make a long story short -- I changed the path to go over the rest of the components (direct path) to a much shorter solid-conductor silver/copper 16-ga feed through a Teflon tube -- found that with some feedback I could dial-in the sound so I then then replaced the pot and resistor with a 80-kOhm Vishay RN-90 bulk-film resistor -- yet again getting rid of "speed bumps." I ended up with a much cleaner treble and a mid-range that seemed to come out of the wall behind the speakers. How many db? I am guessing only about 2-db.
With feedback -- speed is desirable and anytime I have shortened the path in any amplifier the sound improved. The best implementation of negative feedback I found was in the QUAD II mono-block. Schematically the feedback path looks long like any other amplifier. Peter Walker designed the amp. so that path was barely an inch long. One inch. The QUAD II fitted with the original British Genelex (GEC) KT-66s is probably one of the nicest amps I ever had the pleasure of working on and auditioning in my system.