The OFFICIAL Super-7 thread

jeffreybehr · « **Reply #60 on:** 25 Mar 2016, 03:57 am »

I decided a couple weeks ago that as good as I think the c-j ET250S poweramp sounds with the S7s, I want an all-triode tubed amp. Triodephilia indeed! Since I want some 25 - 50 Watts, don't want traditional push-pull operation, and can't tolerate, in my home theater, visually bright vacuumtubes such as the 845 and 805, I looked again at Atma-Sphere's Output-TransformerLess amps. I rejected the stereo S30 with 30WPC into 8 since 4-Ohm speakers were not recommended and landed on the 60-Watts-per-chassis-into-8* M-60s. The A-S amps are now in '3.3' versions which have their binding posts and RCA and XLR connectors on the rears and not fronts. I had purchased a used pair (in 3.1 version upgraded from Mk. IIs) maybe six years ago...

...hoping they'd drive the upper eight octaves of my Vandersteen 5As, but they didn't sound very good (but I don't remember exactly how), so out they went. (I'd hate to think

how many amp combinations I tried with the 5As until I bought a pair of McCormack DNA-750s.)

The Phoenix-metro area actually has a dealer, USA Tube Audio, that sells quite a bit of tubed equipment, and the owner made me a good deal on a new pair. So A-S is building them and I ought to see them in a couple weeks. Wish me luck. In anticipation of having these amps, I bought thru eBay a carton of 25** of the Russian Winged-C 6H13C (the US number is 6AS7G) output tubes for less than $8 each (!), and I retested my 15 Tung-Sol round plate 6SN7s. The M-60 uses four 'N7s (including one cathode follower) in the frontend. Because my system is set up for high gain in the preamp and low gain in the poweramps, I'll likely be using A-S's gain-reduction plugs in the V2 position, so that leaves a total of four TSRPs in the two amps. Hmm...maybe I can use two of the more-microfonic TSRPs in the CF positions...

Meanwhile, the c-j '250 still sounds excellent, so on with the music.

And I'm certainly not admitting to being too obsessive about this kind of stuff, but I'm already investigating stainless-steel and brass blocks (with Herbies' energy-absorbing dots) to damp the middle of the chassis, as I was trying to do with the steel block between the tubes in the upper pic.

* and 45 into 4 and 80 into 16.
** My truly wonderful wife has called me Mr. Excess for good reason.

bdp24 · « **Reply #61 on:** 25 Mar 2016, 04:38 am »

Jeffrey---The M60 is a real nice amp, very transparent. I've had two pairs of them myself, the original Mk.1's in the old style chassis (with a faceplate). OTL amps like a high-impedance load, which was one reason I chose the M60 for my own 16 ohm Quad ESL's (original, not the "57" reissue). You can remove two of the four output tubes per channel and still have enough power for the 57's. A classic combination! Add a pair of Danny's OB/Dipole subs and be happy forever!!

zybar · « **Reply #62 on:** 25 Mar 2016, 11:02 am »

Jeff,

The Atma-Sphere amps worked best with the 5A's when coupled with the Speltz Autoformer. I used that combination very successfully.

You definitely need quiet tubes for the 6SN7's to maximize the magic that the amps can produce.

If you do some research on the Audiogon forums, you can see various combinations that people like.

When I had a pair of MA-1 amps, I combined different NOS 6SN7 tubes to get the sound I liked best - I didn't use all TSRP's.

As always, your mileage will vary.

George

THROWBACK · « **Reply #63 on:** 25 Mar 2016, 01:28 pm »

Not exactly on topic, but not far off either. I am running LS-9s, including triple 12" servo subs per side, with Atma-Sphere MA-1 Silver Edition mono amps (brought up to latest specs). When I first hooked them up, the system experienced a noticeable droop in the highest frequencies. To cure the problem I (aided and abetted by a knowledgeable audio pal) had to make two easy changes. The series/parallel hookup had to be modified to a straight series arrangement to increase the overall impedance into a more OTL-friendly range (I can draw a diagram if necessary). This (plus one capacitor value change) cures the droop and reduces the strain on the amps.

The result: I'm like Tyson, satisfied with my system to the point of not messing with my system much anymore. Now I just listen. Darn you, Danny Ritchie.

P.S. Tyson, I live in Colorado Springs. I have enjoyed your RMAF write-ups and I believe we have similar notions about what constitutes good sound. I think it would be fun to get together sometime. Maybe we already have, since I'm a member of the CAS and perhaps you are as well. Could you send me a PM?

jeffreybehr · « **Reply #64 on:** 17 Apr 2016, 10:44 pm »

Received this week the NEW Atma-Sphere M-60 Mk.3.3 monoamps.

(I later moved that L-channel amp several inches to the right.)

Got them thru the tube-conditioning process* and then a friend and I installed new coupling caps and load resistors**. Friday I finally (in between way-too-late tax-returns work) got them running. Already, with maybe 25 hours on them and with too-long, low-quality speaker and IC cable in the left channel, they sound almost excellent--detailed and spacious but tonally not yet rich.

I have lots of super-high-quality BlackGate and SoniCap Platinum caps to install in them, but I think I'll work on the Super-7s next--new caps, chokes, and mounting plates in the x-overs and all-new wire. I was going to use only Neotec UPOCC-in-Teflon copper and silver conductors, but after placing the monoamps, I realized that I could avoid all 'speakercable' if only the MR wire were a foot longer. That is, I could run the wires attached to the initial x-over parts, unbroken, all the way to the amps' binding posts. So I'll soon be ordering a couple-dozen feet of Mundorf 'MConnect SilverGold'***...
http://www.soniccraft.com/product_info.php/mundorf-sgw110wh-p-4895
...Teflon-insulated 18g. wire to run to the first inductor and from the last cap of the MR filters. After that arrives, I'll start that probably-time-consuming project while the amps break-in.

* A-S recommends that new amps with new tubes be conditioned by operating them with 'filaments-only' (actually, the LH switch turns on all filaments and the frontend tubes' high-Voltage) for at least 24 hours; I got about 30 hours on mine.
** SoniCap 0.01uF Platinums and 390KOhm PRP resistors, to create a high-pass filter of 42Hz for the otherwise-filterless MR drivers.
*** Ninety-nine-percent four-nines-pure silver and one-percent four-nines-pure gold

Tyson · « **Reply #65 on:** 20 Apr 2016, 12:49 am »

I actually have a question on the Super 7's with low power amps. I'm running a First Watt Burning Amp 3, which is 25 watts on tap. Do I even need to put a cap on the input of my amp to high pass at 100hz? With only 25 watts, shouldn't the 4 panels be able to run wide open without that cap in the way?

Danny Richie · « **Reply #66 on:** 20 Apr 2016, 01:36 am »

Quote from: Tyson on 20 Apr 2016, 12:49 am

I actually have a question on the Super 7's with low power amps. I'm running a First Watt Burning Amp 3, which is 25 watts on tap. Do I even need to put a cap on the input of my amp to high pass at 100hz? With only 25 watts, shouldn't the 4 panels be able to run wide open without that cap in the way?

I'd still run it with the cap. It should be a little cleaner that way and allow the amp to have a little more headroom and better dynamics.

Tyson · « **Reply #67 on:** 20 Apr 2016, 02:52 am »

Does putting the cap there mess with the phase at all?

Danny Richie · « **Reply #68 on:** 20 Apr 2016, 01:10 pm »

Quote from: Tyson on 20 Apr 2016, 02:52 am

Does putting the cap there mess with the phase at all?

No.

Ric Schultz · « **Reply #69 on:** 20 Apr 2016, 05:15 pm »

All parts add a sound (some kind of distortion....however, some distortions are NICE). I personally would try it both ways if I were listening real loud in a large room. If you do not listen real loud or have a small room I would not use it. I use one Neo 10 (four can handle way more power) with no cap and I listen to 100db peaks in a small room. No distortion, no problem......for 2 years now. Of course, the cap will help with a big DC surge or whatever. Everyone is different. I am not conservative. I want the best sound possible. You must listen to find that out.

Danny Richie · « **Reply #70 on:** 20 Apr 2016, 05:31 pm »

The cap will limit how far the diaphragm will be pushed too. Those drivers won't play much below 100Hz but they are still effected by them and the lower ranges will really push them harder.

A good quality cap like the Sonic Platinum isn't going to take too much away from them.

And in my case, my pre-amp has coupling caps in it anyway. So I either use one output with a 3.3uF Jupiter cap (full range) or another output with a .047uF Platinum (restricted low end).

But hey, try them both ways. Tyson, you are not putting enough power on them to hurt them at all.

mikeeastman · « **Reply #71 on:** 20 Apr 2016, 06:30 pm »

Danny what is the cut off with the .o47uF cap?

Danny Richie · « **Reply #72 on:** 20 Apr 2016, 06:43 pm »

Quote from: mikeeastman on 20 Apr 2016, 06:30 pm

Danny what is the cut off with the .o47uF cap?

It depends on the input impedance of the amplifier.

mikeeastman · « **Reply #73 on:** 20 Apr 2016, 06:54 pm »

DM impedance is 104 k , CM impedance is 1.5 M What ever that means

HAL · « **Reply #74 on:** 20 Apr 2016, 06:55 pm »

To calculate the f-3dB point for the single pole high pass filter, the equation is:

f-3dB = 1/(2*Pi*R*C) where,

R = input resistance of the preamp,
C = series capacitor value.

As an example, a power amp with a 10000 ohm input resistance and the 0.047uf cap will be 3db down at 339Hz.

bdp24 · « **Reply #75 on:** 20 Apr 2016, 07:10 pm »

Quote from: HAL on 20 Apr 2016, 06:55 pm

To calculate the f-3dB point for the single pole high pass filter, the equation is:

f-3dB = 1/(2*Pi*R*C) where,

R = input resistance of the preamp,
C = series capacitor value.

As an example, a preamp with a 10000 ohm input resistance and the 0.047uf cap will be 3db down at 339Hz.

Do you mean power amp?

HAL · « **Reply #76 on:** 20 Apr 2016, 07:12 pm »

Yes. Fixed it.

Danny Richie · « **Reply #77 on:** 20 Apr 2016, 07:26 pm »

Hey guys, drop in your values and get a quick answer: http://www.pronine.ca/capimp.htm

mikeeastman · « **Reply #78 on:** 20 Apr 2016, 08:00 pm »

The calculator gave me 32 hz with the .047uF, would it be better to use say a .01uF which would give about 150 hz with my amp?

Tyson · « **Reply #79 on:** 20 Apr 2016, 08:07 pm »

Danny, thanks for the info!

Quote from: mikeeastman on 20 Apr 2016, 08:00 pm

The calculator gave me 32 hz with the .047uF, would it be better to use say a .01uF which would give about 150 hz with my amp?

That's what I do.