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My experiences with new M-60 Mk.3.3s, good and not-so-good

70.162.169.147

Posted on April 23, 2016 at 14:28:07
jeffreybehr
Audiophile

Posts: 4953
Location: Phoenix, Arizona
Joined: December 10, 2004
Contributor
  Since:
December 13, 2004
1. First, sound quality--resolution/transparency and smoothness (= nonedginess)--are excellent, even with brand-new everything.

2. Have had some problems with lack of good contact with tube sockets. Had lots of trouble getting one amp to null its DC offset. Thought it was mismatched output tubes or even bad frontend tubes. Played with 16 output tubes (hereafter OT or OTs) and several frontend tubes (FETs)--original Chinese and old Tung-Sol roundpates. Sometimes the cathode follower's filaments wouldn't glow. Eventually worked out a sequence of loading input tubes into the amp and then pairs of OTs, and all has been well in both amps for a couple days. (I experienced the problems in only one amp, I experienced NO OT-internal-fuse blowings, and Ralph was very helpful.) My lesson learned--TY, Ralph--is that the Chinese tubes have slightly larger pins, and sometimes the socket's contacts don't make good contact with my old tubes.
3. Have installed new Cardas CCGR bindingposts, new solid-silver wires to the cap terminals, new Furutech FP-901(R) RCA jacks, two 1uF SoniCap Platinum output-stage-PS bypass caps in each amp, and three strips of SoundCoat the thicker...see link...on each bottom cover. IMO the chassis rings too much, and I'll be adding more of that stuff. (IMO vibrating resistors, capacitors, wire, vacuumtubes, etc., do NOT add to the sound quality, they all diminish it.)
M-60 with SoundCoat on bottom cover photo 2016Apr23_SoundCoat on bottom_1500h_zpszliczxck.jpg

I applied SoundCoat inside the VERY-highly-ringing transformer cover of the 2nd amp.
SoundCoat inside transformer cover photo 2016Apr23_SoundCoat inside T-cover posts and RCA_1800w_zpsh9p5lmpg.jpg
This cover is now DEAD!

4. I THINK the first serious improvement project I'll do is to replace the inexpensive 100/350 'lytic caps in the frontend's powersupply with BlackGate VK-series 150/350s*, bypassed with 0.47uF Platinums. ... But that's a big project, and probably it'll take me weeks to start that. Then I'll replace the output-stage PS caps, and for that I have a bunch of BlackGate 470/160s*.

I've removed the feet from my amps; I'm using the 2"-square Wagner antivibration pads...
 photo 2016Jun08_RC amp_2000w_zps9s1hjral.jpg
...two-high. They seem to work just finely on my carpeted concrete-slab floor.

* that I've been saving for many years

----------
Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."

 

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RE: My experiences with new M-60 Mk.3.3s, good and not-so-good, posted on April 25, 2016 at 08:02:11
Cousin Billy
Manufacturer

Posts: 225
Location: Greater Toronto Area
Joined: September 10, 2004
Contributor
  Since:
October 25, 2015
I too have been fiddling around with my Atma-Spheres. It was more out of boredom than anything else. In my mind the MA-1's started out as the best I have ever owned. I also have the Tenor 75 OTL's in house.
I had to build 'risers' to accommodate my mods.
The Mundorf TubeCaps, like the Blackgates (which was my first mod) do make things a little smoother.
If you look at the bottom right corner of my picture, you'll see the Mundorf 4-pole storage supply caps. I'm not sure how 4-poles would be installed in the M60, though you appear to be more knowledgeable than I. No words can describe the elevated state of 'thereness' of my record collection.





 

RE: My experiences with new M-60 Mk.3.3s, good and not-so-good, posted on April 25, 2016 at 10:04:10
Lew
Audiophile

Posts: 8652
Location: Bethesda, Maryland
Joined: December 11, 2000
I won't comment on the parts swapping. But it seems to me that I see threaded recesses in the bottom of your chassis which might accommodate the threaded male ends of audiophile "footers", if you are of a mind to do that. I wonder why feet of some sort were not included in your shipment.

I am sure you realize this, but go easy on the dampening materials lest you impede the cooling of the amplifier via heat transfer direct to the metal chassis. The cooling is not entirely dependent upon the slotted air vents.

I will send out your 6SN7 this week. Thanks.

 

Lew, of course the amps came with feet; I removed them. :-), posted on April 25, 2016 at 18:43:40
jeffreybehr
Audiophile

Posts: 4953
Location: Phoenix, Arizona
Joined: December 10, 2004
Contributor
  Since:
December 13, 2004
Yes, I understand that the chassis surfaces help cool the amp, but I suspect the bottom cover does very little of that. Probably I'll apply very little SoundCoat to the ceiling of the chassis. Since I'll add little damping to the ceiling of the chassis, I plan to add four stainless-steel bars, probably 3/4-by-2-by-4-1/2" to be cushioned with some sort of Herbies pads, placed on edge atop the chassis, one each between the rows of output tubes and two alongside the frontend tubes. It's easy for me to visualize that, but I expect a few pictures will be worth hundreds of words.
----------
Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."

 

My mistake..., posted on April 25, 2016 at 21:51:59
Lew
Audiophile

Posts: 8652
Location: Bethesda, Maryland
Joined: December 11, 2000
on my first and only reading of your post, I thought you lamented the lack of "feet" and so are using your own solution to that problem.

The best, really only, way I have ever read about (but never used) to cure the "problem" (if it is a problem) of vibrating capacitors and resistors is that spray-on or paint-on compound, can't recall the name of it, that really does dampen vibrations. However, it must be a nightmare if you later want to change out parts or service the circuit. Other than that, one could use double-sided tape and other forms of goop. So what do you do?

One guru on TubeDIY actually recommended keeping capacitor and resistor leads as long as possible and coiling them up so as to allow the leads to act like a spring, in an attempt to decouple the part from the vibration of the chassis. But that leaves the part free in space to vibrate secondary to signal transfer.

 

Got one more amp finished to an initial degree., posted on April 26, 2016 at 22:24:58
jeffreybehr
Audiophile

Posts: 4953
Location: Phoenix, Arizona
Joined: December 10, 2004
Contributor
  Since:
December 13, 2004
Sound-Coated the transformer cover, moved the pair of 1uF Platinums--that amp was humming a bit because I wasn't smart enough the first time to get both caps far enough away from the AC-filament cables--and added a pair of 0.47uf Platinums to the powersupply poles supplying Vs1*.

 photo 2016Arp26_2 prs Platinums_1800w_zpsvrswda8i.jpg

Will get the 0.47uFs installed and the 1uFs moved in the other amp, and then they'll cook for weeks while I fool around building another equipment rack, this time with 80/20 stuff. (Can't afford the rack/s I want.)

* JIC you haven't read Ralph's note, the former V1 is now two 'N7s with sections in parallel, labeled V1a and V1b.
----------
Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."

 

RE: Got one more amp finished to an initial degree., posted on April 27, 2016 at 18:51:10
Leadfoot
Audiophile

Posts: 6
Location: GTA
Joined: April 27, 2016
Hello
Long time lurker and first time poster in ANY forum.

I recently completed a kit build of a pair of M60's and I am loving them. It was a project that was way over my head and with Ralph's generous/patient support I got through it. I have also been bitten by the modification bug and have upgraded signal path resistor quality (same values) to great effect. My question to jeffreybehr (and anyone else who wants to add their thoughts) is; what are the sonic benefits of all of the additional capacitance (bypass capacitors)?
If this has been covered before, please forgive and point me in the right direction.
Thanks

 

The system sounds better all the time., posted on May 13, 2016 at 01:03:43
jeffreybehr
Audiophile

Posts: 4953
Location: Phoenix, Arizona
Joined: December 10, 2004
Contributor
  Since:
December 13, 2004
Finally got the four Platinum bypass caps in the 2nd amp and also made another left-channel preamp-to-poweramp IC. This is of Neotec UPOCC-silver NEI-1001 (?) and KLE Innovations Absolute Harmony highest-quality solid-silver RCAs*.

Also started removing the SuperSubs from the front wall.
 photo 2016Apr17_room w M60s_1800w_zpsvksl29bn.jpg
Tonite we pulled the drivers and then the front panels which left the hollow boxes lined with 2" plastic foam. The subsequent mild damping of the rear wave from the Super-7s has improved image placement and solidity and reduced instrumental blurring, thus improving transparency.

Will be building some panels combining broadband absorption and bass trapping for those about-3'-wide-by-6'-high soon-to-be-blank walls.

HOT DAMN it really sounds better!

* The KLE Innovations connectors are the successor to the Eichman plastic-bodied, low-metal-mass RCAs of years ago; see link.
----------
Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."

 

My latest adventure with these amps had one OT blowing its internal fuselinks., posted on July 7, 2016 at 17:34:29
jeffreybehr
Audiophile

Posts: 4953
Location: Phoenix, Arizona
Joined: December 10, 2004
Contributor
  Since:
December 13, 2004
My cockapooch and I were listening to music when WHAM!, something popped VERY loudly in the right channel and flashed brightly in the RH half of the right-channel amp. Of course we both jumped and she approached the amp, sniffing, but I called her back. The music continued playing and sounded fine, but I turned off that amp and visually checked the fuselinks in the 4 right-hand OTs. Found both fuselinks disappeared in one tube (see link below), replaced the tube with a spare, turned the amp on, rebalanced that amp after it warmed (and again hours later), and all is GOOD. In many output-transformered amps, that tube blowing would have taken with it a large resistor on the board and junked a $50 - $100 tube; my spare OTs cost about $9 each, delivered, IIRC.

I've been merely listening to these amps and my system for a couple months; this summer, in spite of the desert heat in Phoenix, seems to be my season for buying, selling, and shooting pistols, punching paper and blowing up pesky waterjugs. :-)

The system sounds EXCELLENT, and I'm VERY happy I have these amps.

TYVM, Ralph!
----------
Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."

 

RE: Got one more amp finished to an initial degree., posted on July 8, 2016 at 08:48:51
kbsp
Audiophile

Posts: 15
Location: Denmark
Joined: January 19, 2010

Hi,

Bypassing have been long term best practice for us amateurs but I'm not too sure that it's a good idea after all.

Real world capacitors are capacitors with unavoidable small inductance and resistance so we should design our circuits with that in mind that they indeed are resonators at a given frequency.

By paralleling (different values) of capacitors might interact with each others like a parallel resonant circuit. Our perception of an improvement by the added capacitors might not be an improvement after all. Verifying the implementation by measuring the circuit before and after can give us a hint.

So, I believe your intention by replacing the originally 150uF capacitors is the better approach.

For my own DIY M60 I've installed 4-pole electrolytic capacitors followed by electronic chokes followed by polypropylene capacitors. No bypassing.
It does measure excellent for sure but is it really a better implementation soundwise compared to Ralphs approach? Maybe, maybe not.

Ralphs passive PSU design is guaranteed to be long stable solution without any risk for a meltdown of the output tubes nor our beloved bass drivers.

BR.

 

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