Pass Lab replacement - call for Robert Harley

ddetaey -- Wed, 08/13/2008 - 00:16

Dear Robert

Having upgraded my system, replacing my Wilson Sophia 1 speakers with the wonderfull MAgico V3's, I am in hifi heaven.

However, what sometimes has proven to be a challenge is now turning into a real problem. I am driving the Magico V3's with a Pas Lab combo X1 pre-amp and X250.5 power amp.

With the Wilson's the X250.5 ran quite warm which at warmer summer days not allways created a stimulating listening room.

Apparently the V3's are a tougher load on the X250.5 which means the X250.5 runs very warm, even hot. Even with moderate outside temperatures of about 22Â°-24Â°C, my listening room is heatening up to above 30Â°C.

Therefore unfortunately , and for this reason alone,I will be forced replacing my Pass combo.

As you are quite familiar with the Magico V3's, would you be able to recommend some brand(s) which could drive the V3's well, sound at least as good as the Pass Labs and would run 50% cooler?

Thanks for your interest and support.

Dirk

Robert Harley -- Wed, 08/13/2008 - 11:37

Dirk:

I didn't find the V3 that difficult to drive. I alternated for a few months between the Revel Salon2 and the V3, and the V3 was a much easier load for the Mark Levinson No.433 (200Wpc) amplifier. I also drove the V3 sucessfully with the Naim Nait5i, a 50Wpc integrated amplifier.

Could there be other factors that appear to make your Pass amplifiers run hotter?

The Pass amplifier you have is less succeptible to running hotter as it works harder (compared to other amplifiers) because it is more heavily biased than most amplifiers. This means it runs hotter intrinisically at low to moderate power.

I just finished reviewing the Pass XA100.5, a pure Class-A 100Wpc monoblock, and the first Pass product I've had in my system. If the X250.5 sounds anything like the XA100.5 (it probably sounds quite similar), you'd be hard pressed to find a better sounding amplifier. The XA100.5 is truly remarkable.

If you decide that you must get a cooler-running amplifier, the Spectral DMA-360 is fabulousâ€”and a terrific match for the V3 (Alon Wolf has a pair of DMA-360s that he used during development). I had the DMA-360s and the V3 together for just a few days, but the result was spectacular. The Spectrals really "lit up" the V3, and brought out all their best qualities (and the V3 revealed what a great amplifier the DMA-360 is).

I'm using the DMA-360 now to drive the Wilson Alexandria X-2, and will have a full review in Issue 187.

Dicky (not verified) -- Tue, 04/14/2009 - 09:50

Dear Robert:

I am love the spectral products, Can I buy it directly from the spectral or where I can get it?

Thanks

Dicky

Robert Harley -- Wed, 04/15/2009 - 12:03

You can buy Spectral products through a network of high-end dealers. Check out spectralaudio.com for a full listing.

ddetaey -- Thu, 08/14/2008 - 12:06

Thanks for your reply.

Indeed the V3's are not that difficult to drive, but probably are more reactive than the Wilson Sophia 1's I had before.
Even with the Sophia's, it was not allways easy to play music in summertime because of the Pass Labs heavily biasing. It only became just a bit more difficult.
If only Nelson could build an amp with the same sonic signature runnig in AB-mode (not generating all that heat), wouldn't that be wonderfull.
I really love my X250.5 and it's replacement really will need to excel.
I am happy that you will publish a review on Pass Labs, since they deserve more attention that they get now. I do appreciate that they let their produxts speak for themselves and are not coming out 'strongly' themselves.

That said, I will for sure give the Mark Levinson's and the Spectral's a carefull listen. The nice thing about the Spectrals is that it is the same distributor - More Music in the Netherlands - as for Pass Labs. And they deserve really a complimetn , since they are one of the only few, that really make efforts to follw the US$-EURO rates.

Couple of questions to close :

1) Any experience/comments on the reliability of the Mark Levinson's products, especilly on volume regulators. It still seems to be a weak point.

2) Any comments on Ayre products. Their MX-R power amplifier looks great and TAS has giving it high appraisals. However they work in Class A, so probably running warm as well.

Thanks for your feedback, and keep up the good work with The Absolute Sound magazine. I feel it is continuously improving, especially with the approach looking at market segments such as the reports on music servers in the last received printed edition.

Robert Harley -- Thu, 08/14/2008 - 15:42

Thanks so much for your comments about TAS, Dirk.

I've had no problems with the Mark Levinson No.326S preamp and No.433 power amplifier after about a year of daily use. I also haven't heard from readers about any reliability issues.

We didn't review the Ayre, and I have no experience with it.

The XA100.5 runs remarkably cool for a Class-A amplifier, but that probably won't solve your problem. There's no free lunch.

The V3 really likes plenty of power behind it, and seems to come even more alive with a big amplifier.

ddetaey -- Wed, 08/27/2008 - 15:51

I just have enjoyed a couple of days of listening with a combo of Spectral DMC-15 pre- and DMA-250 power amplifier with my Magico V3's. And I am really stunned about this equipment : far more details than the Pass Lab combo, without becoming aggressive, more neutral without becoming lean, wider and far more deeper soundstage, bass even better controlled.
And than best of all, what a speed without loosing timbre.
At first I could not believe wwhat I was hearing, and that such a detailed system would easily create listening fatique. After 2 days of thorough listening I have to admit the opposite, this sytem pulled me into the music more than ever before.

I will definitely do further auditioning with other amplifiers ( Mark Levinson and Ayre are in the planning), but for now I have a new SPECTRACULAR reference.

Bob Nystrom -- Thu, 08/28/2008 - 20:12

Just passing through and noticed the reference to Spectral amps. I have Avalon Eidolon Diamonds, and I demoed the DMC-15, DMC-30 and DMA-250. In my opinion, the DMC-15 had more room stuff and delicate details going on than the DMC-30. BUT- I needed the remote control, so I went for the DMC-30 and DMA-250. A bit later, I demoed the DMC-30SL, and that was really nice- it closed the gap with the 15 and has a very nice mid range. I traded in my DMC-30. Then I made the "mistake" of demoing the DMA-360's. I nearly dropped my pants- in fact, I think I did!
I had assumed the 250 was essentially equivalent to the 360's. Well, they have the same lineage, but what a difference! The whole sky lit up with the 360's, and I now own them.
The only "drawback"- if that's even remotely the right word- is that Spectral requires the MIT cabling from pre to power amp, and power amp to speakers. The trick to having really wideband amplifiers and keeping them stable is to control the wiring and grounding. So, if you have whims about changing cables for fun, I would think twice about impulsively swapping out cables! Of course, from signal source to preamp is fair game.
As for power cords, I've beaten that to death, and boy do they make a difference. I have my favorites...

Robert Harley -- Thu, 08/28/2008 - 21:18

Previous Spectral amplifiers have been outstanding, but the DMA-360 is clearly in another league. I'd be interested in hearing which power cords you've used successfully with the DMA-360. I'm using the MIT Z-Cord III into a MIT Z-Stabilizer and Z-Cord II from the Z-Stabilizer to the DMA-360s.

Bob Nystrom -- Sat, 08/30/2008 - 18:16

Hi Robert!
Well, you asked. Looong answer- No way to cut to the chase. Sorry.
Background:
Equipment: Spectral DMA-360's, DMC-30SL, dCS LaScala and Dac, Avalon Eidolon Diamonds. I presently have the Spectral/MIT "stock" MI 350 Ultralinear II IC from 30 SL to the 360's, and the "stock" MH-770 speaker cables. I have substituted other MIT cables (Oracle), and have been playing with their new "switchable" IC, but so far no (buying) conclusion. Having designed wideband amps in my dim past (I'm a EE, analog, digital, and software), and full well understand all the ramifications, I'm not ready to tempt the wide bandwith gods- yet.
As far as the IC from dCS to DMC-30, and all the power cords, that's another story.
Room and my Goal:
My room tends to be a bit on the mid bass boomy side, which I've beaten down with resonators, diffusion, Bag End E-Traps and absorption. I've even dallied with Rive's PARC, which is- IMHO- a very good bass parametric EQ. However, I find it compromises the 360's too much. So, I've tried to stick to doing it acoustically. Bottom line: I tend to go for a bit more 'polite' bass, and that's what I've looked for in the cables.
Cables
I have tried:
IC's- Stealth, Acrolink, Audioquest, MIT, Nordost (Valhalla), VH Audio, JPS Labs, Synergistic Research, SilTech.
PC's- Nordost (Valhalla), MIT, Bybee, VH Audio, JPS, Synergistic, Shunyata and home brew
So, in total I needed 5 PC's and 1 XLR IC. I'm not including the pre to power or the speaker cables here. I did mess with those, but the permutations become endless. That comes next.

Some General results, in no particular order:
VH Audio- Airsines and Symmetry IC's. Really very nice. A bit laid back for my room. At the time, I was having some power line issues (now resolved) and couldn't spend more time with these.
MIT- Seemed to develop heavy bass. I found some combinations to be a bit 'nasal'.
Nordost Valhalla IC and PC's- thumping bass, bit forward mids. Somewhat too much in my room.
Shunyata- Anacondas, Hydra- created a "disclike" stage. Height shrunk, but became very wide. Dark between insturments, but lost too much sparkle for my ear.
Synergistic- Tesla series, Hologram A, D and Apex IC.
JPS- Kaptovator and ALuminata's

Bottom line:
Came down to a match between Synergistic and JPS. Synergistic had a wider stage, but JPS had a taller and deeper stage, and was very, very smooth with no rough edges. Exquisite female vocals. Synergistic may have a slight edge in a more live room.
JPS Kaptovator on the 360's produced substantial bass, not boomy, but very driving. Too much for my room. I like the Aluminata's "kinder" bass.

Surprises:
1. The DMC-30SL was the toughest to match to a power cord. It simply did not like many that I tried (versus the included garden variety IEC cord). The pre could become very edgy in the mids. It was the happiest with the Aluminata and Hologram A.
2. The next toughest was the dCS DAC, then the transport. The 360's were the 'easiest'.
3. Aluminata break in- Granted, I haven't tried THAT many cables, but the break in was quite dramatic. The first few days truly suck. Over the next week, I spent time with toe-in and out (1/4 to 1/2") as they aged. It was really quite remarkable, and it genuinely takes almost a month. Another note- once these are in place, don't move them! Just small movements (like re-routing a PC) "dulls" the cables for 30 minutes or so. However, I've noticed NO issues with sonic vibrations causing wierdness. JPS's shielding is absolutely dead quiet. By the same token, they are heavy, but manageable. Just bend them slowly. Superb vocal presentation.
4. I could create the Shunyata effect (disk shaped stage) with clamp on ferrites on regular PC's, and the Hydra effect with a larger core and multiple wraps of the regular PC.
5. I have 3 dedicated lines from my panel. The system is happier with the pre and power amps on one circuit, and the Dac and transport on another (both on the same AC leg).
6. If you want bass, get a Zero Surge suppressor. I use them in the business world- probably the best surge suppressor you can buy. They are relatively cheap ($100 ~ $150). They are basically a tuned circuit- choke and capacitor, with no movs to fail and burn down your house. Here's the trick- you don't need to plug anything into them- just plug them into the same circuit as the 360's. In my setup the difference is quite stunning. In truth, I only use them when the unwashed masses come over and want their bodies thumped. It's even more profound when you plug the amps into them- I use one per 360 (to thump the masses).
Disclaimer: As I discovered, the effect is quite dependent on some power line issues (damn the neighbors and their well pump!)

Last- After flogging this as a power cord disbeliever, I'm now a firm disciple. As to why they do what they do, I have my half baked but modestly experimentally proven engineering answer. If you think this post is long, don't ask....

Robert Harley -- Mon, 09/01/2008 - 10:11

That's quite some experience you have with interconnects and cables. I'm intrigued by the Zero power conditioner you mention.

I also once doubted that power cords could make a difference until I heard it for myself. I was reviewing two similarly priced power amplifiers, one of which came with a specialty AC cable (the other amplifier came with a generic AC cord). I was going back and forth comparing the amplifiers and had a good handle on how each one sounded. Out of curiosity, I switched power cords and some of the sonic characterisitics I had attributed to one of the amplifiers appeared in the other amplifier. That is, I was listening to the differences in the power cord. That was in 1990, less than a year after I started reviewing as a full-time job.

Mitchell Erblich (not verified) -- Thu, 04/16/2009 - 14:03

This is probably not the most hi-tech solution, but the first question is other than heat, do you like the Pass Labs? If the answer is yes, then IMO, I would first make sure that al the air-ducts are open to the room. Try running the fan first, to see if just a few extra cubic feet per min of air movement fixes your problem. Else, i would install an additional duct to the room or/and cool down the room before you do your listening session. Lastly for my comment, please realize that running a amp at 1/3 power will probably produce the most heat, so going bigger or smaller may reduce the heat of the amp. Adding a separate sub, with a xover should reduce the load on your mains. However, If I had to replace a "Class A" amp every time it got hot, then I would need Warren Buffet's money..

Robert Harley -- Fri, 04/17/2009 - 11:35

I knew a speaker designer who built the listening room in the factory around the Audio Research Reference 600 amplifiers (the forerunner of today's Model 610t). He had to have the Reference 600s, but couldn't deal with the heat (they have 68 tubes between them, most of them 6550s). The solution: Build a separate room for the amplifiers with an air-conditioning duct to the small separate room.

I find that the Pass amplifiers don't run so hot that I need to make special accommodation for them, although I've been using them only through the winter months.