Can we get some updates on what is going on with the new backplate and transformers...It has become deafeningly quiet here on the topic???  Thanks...Texas David

The new Torid II updated transformer seems to be considered a winner by many. Sound Lab has had 1/2 a dozen pair of back plates come to the factory recently for the upgrade. Most everyone, myself included, will want it, sooner or later.

My ears are just OK, and I like the change to the new toroids. But Jared Sacks, owner of Channel Classics remarked that the speakers sounded warmer, more natural than before the change. His ears I trust. The new toroids are on the front three panels however, with the two rear retaining the old toroids. All panels are M-1PX.

Since there is so much curiosity about the toroids II, I thought that I would give my input, since I installed them myself. If you buy the toroids, the price is $1575, plus about $32 shipping in the US, quite a saving from the $2250 to have them installed. The bad news: the installation is not really plug-and play, because the big toroids cannot clear the rim of the upper edge of the case. That means that you have to install the plastic over shield, then bolt in the toroid, then cut out a small section of the wood case (lower right) to fit the new setup in. You also have to remove the mixer to get to the blue and red bananas, as well as taking out the toroid bracket and redrilling the mounting hole (needless to say, you need a longer 1/2" bolt, because the transformer is so much wider.
For those of you that have replaced the R/C stuff with bigger items, they probably have to be relocated (I had to relocate my big Claritys).

If you have a drill press, solder experience, and a Fein Multimaster to make a need notch in the base, very nimble fingers, etc. go for it,.

Now for the important stiff: the sound is fabulous and the loudspeakers seem to have more presence, warmth and realism: this mod is definitely worth every penny.

Did you change the values of the Xover R/C's? If so what were they changed to?

Thanks,
John

I have a setup where I can plug in cap and resistor values. The diagram that comes with the mod shows 24 microfarads cap and (4) 8 ohm resistors. Having tinkered with this a lot, I am using older values: 36 microfarads for the cap(s) [a mixture of claritys 34 uF and 2uF and .01 trimmers]. This sounds very fussy, but it works for me. The resistors are 10 ohms.  Actually this setup works better with the new toroids, because they change the crossover to 500Hz, as opposed to 350 Hz.  his setup also complements greater presence that the loudspeakers have. Another thing: the efficiency of the SL's has increased markedly. I am using 600W Bryston monsters, but I guess that a really good 200W tube amp would be most ideal. One last thing: you may want to tinker with the bias; however, wait at least one day for the system to be fully recharged.

I was going to add that , although the Sound Lab people did not think that any burn in time was necessary for the new toroids, after 48 hours, the sound in my rig has definitely improved and smoothed out. My guess is that the new transformers will need at least 100+hours of burn in to really shine.

This is a very important message regarding pricing of the toroid upgrade. I received a special discount because I am a professional in the music trades. The real price for just about everybody is $2250. Please accept my apologies for unintentionally misleading anyone on this matter. My situation result of years of working with Roger West at Sound Lab and exchanging any kind of data that both of us deemed relevant. I would say one thing: the official price is worth every penny. if anyone wants any information about a DIY installation, I will help in any way that I can.

I am really surprised that in all this time, nobody has had anything to say about toroids II. Am I the only person out there who has a pair?
I got some interesting stuff from Dr. West about the use of 24uF vs. 36uF caps (with appropriate resistors) and the green wire vs. the brown wire in terms for response and the nature of listening rooms (dead vs. live). It seems that there is some latitude about how to set up the new transformers.

I have had my Toroid II's for a couple of months now. My previous configurations included the 24uF cap mod from William (thanks, William), then the Aussie Transformer mod with no caps or resistors, then back to the Toroid I with 10uF oil-filled caps (thanks Canada Dave). I was pretty happy with the last modded configuration. So why did I change? I heard M-1's with the Toroid II's at CES and talked at length to Roger West about the mod. He is a modest man and not pushy about his new product at all. Although the listening environment was totally different than that found in my living room, I heard enough to make me think I could do even better with the new mod than with what I had.

I am now running my M-1's with the Toroid II's in totally stock mode and it has the best sound yet in my listening room. I have zero motivation to mod further. The positive impacts on dynamics, efficiency and clarity were well worth sending my backplates back to the factory for.  I would have liked to have run the M-1s without my subwoofers, but find I still cannot. But that may be due to: 1) a matter of taste; 2) my altitude (close to 7,000'); 3) my choice of amplifier (currently, Wolcotts). Nevertheless, I am a happy guy. My listening group members are very keen on the sound I am getting now. They were not so thrilled before.

I appreciate all the advice and ideas I have received on this forum.

I am curious if you tried any other amplifier with your M-1's with the new toroids. Also do you find that  the efficiency of the loudspeakers has increased markedly (I have my preamp default volume set down 13 dB). At first I found the sound to be a little brighter than before, and I rolled back the brilliance control to about the three o clock position. However, as time goes on the brightness is smoothing out.

I have to revise my estimate on the breakin period for the toroids: I would say that 200-300 hours is more likely. I would like some feedback from those other lucky owners who are playing with this mod.

Hi p_reale,

In response to your request, here goes:  I just received my U1-PX (90-degree dispersion) backplates which were upgraded by SL to the "Consummate" level (Hot-rod version plus Toroid II).  I've listened to the speakers for under 10 hours, so this is a very preliminary assessment of the resultant sound based on recordings (LP and CD) I'm familiar with:  tighter bass response (but not necessarily deeper as of right now), greater clarity and transparency yielding more apparent detail, smoother highs, and in general, a wider and deeper soundstage (recording dependent, of course).  I agree with you that 200-300 hours would be an optimal break-in period.  It took my PX panels about one year (over 300 hours) to really shine.  

Regards,
RM

Good to know that there is a still a heart beat at SLOG. Hippy!!!

I have played with more transformers on the Soundlab than most, believe me!

For those who can appreciate the difference between a gold fuse and a standard one in the backplate .... maybe 300 hours of breaking in a transformer can be perceived.

Reminds me of an Audioplhile friend I had that was dead set that the latest and greatest interconnect he bought was as good as the review he read. "Oh a bit bright but it will mellow out with break-in."

3 months later I visited him and heard the exact same sound. "William, it is now broken in and don't it sound much sweeter?"

"Yes Fred, your ears has definitely broken in. All good! Let's go to the Pub."

I have a little more to say about the breakin period. I don't think that the initial brightness of the setup was subtle. however, there is a definite easing up of that effect after about 100 hrs. I continue to hear an increased smoothness as the setup ages. In this rarified area where the sound is so good already, listening to recordings that have been familiar for decades will reveal a great deal. Naturally, the listener is gratified by the increased definition over the range, but any compromise in smoothness will jump out. I also found myself fiddling with the bias control after a few days of use.
ultimately, the increased efficiency will allow the user to try more different kinds of amplification.

Dear P-reale, Can you say just how the four 8-ohm resistors are configured?  Typically SL uses the resistors in series/parallel arrangement so as to end up with a net value (in this case) of 8 ohms.  If that is so for the new toroid, then R= 8 ohms coupled with C = 24uF would give you a higher hi-pass crossover than would 10R paired with 36uF.  Yet I think you commented the other way around. Did you misspeak, or did I misread? Thanks.

Having said that, I am surprised that SL still aims at a 500Hz, -3db point.  I would have thought that part of the reason for the new toroid was to make possible a lower crossover point. 350Hz sounds right.