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First venture into SETs.

96.3.196.74

Posted on July 6, 2016 at 07:14:26



I've spent a few days now with a new set of direct-heated 2A3 monos by Larry Moore, and my initial impressions are very good. They do seem to be pretty fussy as to vibration, so getting them to play nice with the subs is a tricky undertaking. Attention is also needed on cabling and just getting everything dialed in, but I can see (and hear) the potential, so I'm clear the effort will be worth it.

 

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RE: First venture into SETs., posted on July 6, 2016 at 08:48:28
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
Very good, Larry builds nice two stage SE amps.

The vibrations mainly come from the power transformer.

On a temporary basis, just the HEAR it, carefully place concrete bricks on the power transformer, and on the horizontal surface of the amp, to mass load the amp. Try up to 8 bricks, incrementally.

LISTEN to what that does !! Don't scratch the top plate. Add and LISTEN. Have fun.

Jeff Medwin

 

RE: First venture into SETs., posted on July 6, 2016 at 09:58:06
Apologies for not being clear. It's external vibration (strong bass frequency energy) that seems to be a bit problematic, which isn't the amp's fault at all. It's just a matter of my finding out how to address the issue, although I don't doubt mass loading would effect some improvement.

 

RE: First venture into SETs., posted on July 6, 2016 at 10:54:19
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
That is probably more of a room/speaker placement issue than an amp issue in this case. Someone else, who is more knowledgeable than i am, can comment on this.

 

I agree., posted on July 6, 2016 at 11:05:04
I'm slowly getting it dialed in, but it does take time and experimentation. I see some cable changes in my future soon as well. With the external crossovers on the Odeons and the amps being right next to them, I can virtually eliminate speaker cables, and just use a short set of jumpers.

 

RE: First venture into SETs., posted on July 6, 2016 at 11:05:32
hifipaul
Audiophile

Posts: 735
Location: NY
Joined: December 22, 2008

Welcome to the asylum. Damping foam and mass cure most vibration issues. There is a good thread about industrial damping blocks in the tweaks asylum.

 

RE: First venture into SETs., posted on July 6, 2016 at 12:13:34
You gave me an idea. I had forgotten that I had several sheets of a sorbothane-type of material lying around unused, so I assembled them sticky side together to make 3/16" thick pads for each amp and the external crossovers. A very definite improvement. Thanks for the idea.

 

RE: First venture into SETs., posted on July 6, 2016 at 17:31:35
bcowen
Audiophile

Posts: 1076
Location: North Carolina
Joined: December 19, 2015
Todd,

Beautiful amps! Welcome to the fewer/better watt club. :)

Is that one of your subs directly beneath the table the amp is sitting on? If so, changing that arrangement will likely yield immediate benefits.

Personally, I'm not a big fan of sorbothane/Navcom or other squishy-type vibration taming methods. While those materials help in some ways, I've always found them to deaden and suck all the life out of the music, especially with tube components. If you've got some cones around, give those a try. Point down onto the table, and the plate of the amp directly on the top of the cone (bypass the factory feet).

 

RE: First venture into SETs., posted on July 6, 2016 at 18:34:39
You're right, of course. Sharp eyes, by the way.

I built those bridge tables due to severe space limitations in the house I'm living in. The floors are concrete, so it was my thought that I could get away with it. Maybe, not so much...

I'll talk with Larry in the next few days and get his take on it.

 

RE: First venture into SETs., posted on July 7, 2016 at 10:41:48
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
+1.

Stillpoints, or look at Mr. Walker's cones, Walker turntable fame. Really nice design.

Bricks applied to AMP will allow him to hear mass loading, on 'de cheap, and it gives one direct experience, which is a great approach.

Jeff

 

RE: First venture into SETs., posted on July 7, 2016 at 18:40:54
Nice amps! Maybe, a granite slab under each amp?

 

RE: First venture into SETs., posted on July 8, 2016 at 06:35:06
That's certainly a possibility. Another inmate had good success putting blocks of ballistic rubber under his speakers, so I had considered putting a 2" slab under the subs and bridge tables to isolate them from mechanical transmission of vibrations, although that would do nothing for acoustical transmission. There are a couple of suppliers in MN. A slab of rubber under the subs and tables with a stone slab on top of the table might be the ticket - then put some points underneath the amps and call it done. Or I might be better served by making a set of wall-mounted shelves to put the amps on. I'll figure it out, although I'd like to test some of the principles before springing for the materials.

 

RE: First venture into SETs., posted on July 8, 2016 at 18:36:20
Maybe small, portable acoustic panels surrounding the amps? These work well when recording.

 

RE: First venture into SETs., posted on July 10, 2016 at 06:47:21
johnsonad
Audiophile

Posts: 759
Location: Central California
Joined: June 9, 2008
Mass loading helps and it's easy to try with anything dense and heavy. For feet, I've had good results with Herbies Tender Feet. They are equal to if not better than sorbathane and they will not loose their shape. I had a tricky preamp that was highly microphonics and those feet with a little mass in the right place took care of most of it.

 

RE: Part of the problem..., posted on July 10, 2016 at 12:42:13
Thanks for the tip.

Part of the problem was that the sub levels were much too high. I'm running the mains full range, and set the subs to roll off early so they just fill in the extreme low frequencies. Most music doesn't go down that low, so it's a little hard to get it right, but an afternoon with an SPL meter and the setup CD helped considerably.

 

RE: First venture into SETs., posted on July 12, 2016 at 01:43:14
morricab
Distributor or Rep

Posts: 9160
Location: switzerland
Joined: April 1, 2005
You are finding the power of a single 2A3 to be adequate?

 

RE: First venture into SETs., posted on July 12, 2016 at 06:35:49
It appears so, given my room and listening habits. I may have told you that Larry built them for unusually fast transient recovery (which helps), and I'm not inclined to listen at high volume levels in any event since my high frequency hearing is already pretty much gone by 10-12K Hz and I'd like to preserve what I have left. I have yet to find myself wishing for more volume that I have. A little more "slam" might be nice, but I'm not even sure that more could be considered to be a realistic presentation. I haven't tried anything other than the Sovtec 2A3s they came with either, so it's entirely possible that a little tube rolling might address any perceived shortcomings.

Overall, I'd have to say that I'm happy with them.

 

What does Larry say? nt, posted on July 12, 2016 at 14:23:51
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
nt

 

Haven't heard back., posted on July 12, 2016 at 15:36:41
I left him a voice mail, but haven't received a return call. I'll have to call him again.

 

RE: First venture into SETs., posted on July 13, 2016 at 16:39:38
Genp
Audiophile

Posts: 57
Location: Not far from Montreal
Joined: February 19, 2016
Nice amp! What opt is on top?

 

RE: First venture into SETs., posted on July 13, 2016 at 17:11:07
"What opt is on top?"

Opt=??

 

RE: First venture into SETs., posted on July 14, 2016 at 06:02:14
Genp
Audiophile

Posts: 57
Location: Not far from Montreal
Joined: February 19, 2016
"output transformer". There is also "OT".

 

RE: First venture into SETs., posted on July 14, 2016 at 06:24:32
Ah, ok. Thank you.

The silver one is by a company called James Audio Transformer.

 

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