Oh-m'-god--bought a pair of MA-1/3.1s thru USAudiomart.

Dec 16, 2018
25
8
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74
Phoenix, Arizona USA
#1
https://www.usaudiomart.com/details/649467350-atmasphere-ma1-mk-31-amplifiers/

If that $16,900 retail price is correct, my delivered price is only 38% of RR.. The seller was anxious to get them OUT of his house and shipped them yesterday.. I expect these will sound a bit more 'comfortable' driving the Quad 2905s.. I have more than a complete set of Winged-C 6H13C output tubes on hand and, of course, more than a dozen Tung-Sol oval-plate 'N7s for the input and driver section.

2016731-atmasphere-ma1-mk-31-amplifiers.jpg
2016737-atmasphere-ma1-mk-31-amplifiers.jpg
 
Likes: tima
May 27, 2013
419
5
18
Chicago suburbs
#2
Congrats on those amps which should sound exceptional driving the Quads! :) They do generate quite a bit of heat though... I have a buddy who used to own similar Atma-Sphere amps and he got used to listening in his underwear (and I'm not kidding!) :eek: All the best in the new year!
 
May 25, 2010
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SF Bay Area
#3
https://www.usaudiomart.com/details/649467350-atmasphere-ma1-mk-31-amplifiers/

If that $16,900 retail price is correct, my delivered price is only 38% of RR.. The seller was anxious to get them OUT of his house and shipped them yesterday.. I expect these will sound a bit more 'comfortable' driving the Quad 2905s.. I have more than a complete set of Winged-C 6H13C output tubes on hand and, of course, more than a dozen Tung-Sol oval-plate 'N7s for the input and driver section.

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Very impressive looking! Are you the Jeffrey who owned (owns) an audio shop? Welcome to WBF.

Larry
 
May 25, 2010
823
58
28
SF Bay Area
#5
Owned, initially with another Jeffrey, Two Jeffreys Audio, a very parttime effort in my musicroom.. From TAS issue 36:

View attachment 47084
Long gone, fortunately.
Thanks, I remember buying some records from you back in the latter part of the last century! Larry
 
May 30, 2010
14,520
226
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Portugal
#8
TYVM, Tim; now I have a name to connect to 'tima'.

Your observations on the MA-1 parallel the seller's of 'my new' MA-1s. It'll be hard waiting until Jan. 08 when the '-1's are scheduled to arrive. :rolleyes:
Just to point that even if you wrote that " Ralph Karsten claims that the Mk 3.1 MA-1 is the lowest-distortion tube amp he has encountered. And after thirty years in business, Ralph has encountered a lot of tube amps. " the mk 3.3 version has significantly lower distortion due to a small modification in the biasing scheme!
 
Dec 16, 2018
25
8
3
74
Phoenix, Arizona USA
#9
Just to point that even if you wrote that " Ralph Karsten claims that the Mk 3.1 MA-1 is the lowest-distortion tube amp he has encountered. And after thirty years in business, Ralph has encountered a lot of tube amps. " the mk 3.3 version has significantly lower distortion due to a small modification in the biasing scheme!
...and running the input-gain-stage triode sections in parallel, and using a solid-state (MOSFET) current source, and maybe more I don't remember. :)
 

Gregadd

WBF Founding Member
Apr 20, 2010
6,559
14
38
Metro DC
#10
It should be noted Ralph has some different ideas on distortion.
 

Ron Resnick

Site Co-Owner, Administrator
Jan 25, 2015
5,570
316
83
Beverly Hills, CA
#11
Congratulations,! I am sure you will love those amplifiers!
 
May 30, 2010
14,520
226
63
Portugal
#12
...and running the input-gain-stage triode sections in parallel, and using a solid-state (MOSFET) current source, and maybe more I don't remember. :)
I think that some MA1 mk3.1's already incorporated the parallel triodes and as far as I know the current source is still tube in the amplifiers. The only solid state I know about in the amplifiers was a HV regulator. But the information on the mk3.3 is scarce.

BTW Ralph Karsten is a frequent poster at Audiogon - see https://forum.audiogon.com/users/atmasphere/posts
 
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Dec 16, 2018
25
8
3
74
Phoenix, Arizona USA
#13
I think that some MA1 mk3.1's already incorporated the parallel triodes and as far as I know the current source is still tube in the amplifiers. The only solid state I know about in the amplifiers was a HV regulator. But the information on the mk3.3 is scarce.

BTW Ralph Karsten is a frequent poster at Audiogon - see https://forum.audiogon.com/users/atmasphere/posts
The current source went MOSFET--the tiny circuit board just right of center...
2016Arp26_2 prs Platinums_1800w.jpg
...and the input triodes doubled with the 3.3s.
 

tima

Industry Expert
Mar 4, 2014
415
86
28
#14
Just to point that even if you wrote that " Ralph Karsten claims that the Mk 3.1 MA-1 is the lowest-distortion tube amp he has encountered. And after thirty years in business, Ralph has encountered a lot of tube amps. " the mk 3.3 version has significantly lower distortion due to a small modification in the biasing scheme!
Are you really saying a newer version that was not available at the time of the article has lower distortion than the older release??
 
Dec 16, 2018
25
8
3
74
Phoenix, Arizona USA
#15
The first of the pair arrived yesterday. Pulled the bottom cover, looked around, shot some pics, installed the (nineteen!) tubes, and installed it in place of one of the M-60s.
2019Jan07_bottom open caps down_1500h.jpg 2019Jan07_bottom open caps up_1500w.jpg

The second should arrive this afternoon.

This larger, bent-aluminum (?) chassis vibrates significantly worse than those of my M-60s did before I damped them; I imagine I'll use two full sheets of SoundCoat the Thicker on the chassis ceiling and transformercover. Seems to have the same Voltage sensitivity as the M-60, so one M-60 and one MA-1 work plenty OKly as a pair. ... :)
 

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Dec 16, 2018
25
8
3
74
Phoenix, Arizona USA
#16
The second amp arrived Tuesday afternoon in a new outer carton; one upper corner of the original A-S carton was slightly wet, but everything inside was OK. This time I removed the transformer cover to see what the big PS caps were--Corn.-Dub. 27000/160s, which Ralph says is or at least was the upgrade option. Got the tubes (including Chinese output tubes and four Tung-Sol oval-plate 'N7s) sorted, nulled, and the amp running. Over the evening, I installed tube dampers and VPI Magic Brick and other vibration dampers.

The amps sound excellent playing a movie, and that's as ambitous as I got.

Current upgrade plans are to install Cardas binding posts (the 'all-rhodium' CCRR Ss) and XLR inlets (the CM F), apply a substantial amount of 'SoundCoat the Thicker' on the chassis ceilings and transformer cover, replace the coupling caps with those glorious-sounding Miflex KPCA (copperfoil/paper & 'propylene/oil), and add PS-bypass caps. The latter will be, on each of the huge main-supply caps, a BlackGate* 470/160 and a 1uF SoniCap Platinum**. At least the BGs (and probably the Platinums, too) will go under the transformer cover. On the frontend supply, I'll use one Miflex 0.47 per amp.
2019Jan09_R ch running_1500w.jpg
Soon I'll determine what size dampingbars can be used atop the amp in the 4 'aisles' between the rows of tubes. I'm hoping a 1"w.-X- 1-1/2"h. bar will fit, front-to-back, from the meter panel to within an inch or so of the front edge of the amp. I HATE VIBRATING CHASSIS!!!!!!!!!!!!!!!!!

* I have 6 left in my now-very-small stash.
** Teflon-alloy film and tinfoil. I find these to be extremely resolving and tonally balanced.
 
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Dec 16, 2018
25
8
3
74
Phoenix, Arizona USA
#18
Parts are here!

Since everyone is out of my preferred, thicker Soundcoat, lucky me I still had three new sheets in inventory, and that's the FIRST thing going into the amps.. Black caps are 1uF SoniCap Platinums for main-PS bypassing, large brown ones are Miflex KPCU-copper frontend-PS bypasses--and WOW these 600VDC copperfoil caps are BIG!--smaller Miflexes are 0.1uf couplers, bindingposts are Cardas CCRRs, XLR connectors are Cardas CM-Fs, and hookup wire is Neotec UPOCC 18g. copper from my inventory.
 

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Likes: Sablon Audio

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