Start here and come back...
http://www.audiocircle.com/index.php?topic=82134.msg789688#msg789688Sorry for the embedded links from thread to thread, but I think in the interest of representing what I'm finally hearing with the Double+ it was appropriate to start a newer thread.
We need to get one thing out of the way before we continue - I got my Double+ and my X1 back at the same time. The X1 was sent back to Pass for a general checkout and to have the overall gain reduced (this is a standard thing they can do to the X1 if requested as part of a preamp checkout). They reduce the gain by increasing the resistance before the Universal Gain Stage (for anybody that knows how Pass preamps are put together), and by switching in resistors after the UGS. When I got my X1 back the first thing I noticed was that the fundamental nature of the sound was not right. Long story short I use long ICs to my amp and the increase in the X1 output impedance was not good for this setup. Fortunately, the way Pass does the output resistance change it can be completely reversed to the original output specification by simply moving jumpers on the preamp mainboard (pretty smart). Once I did this, the resistance before the UGS remained modded, but the output was back to original specs and things sounded like they should. Since the UGS effectively decouples any relationship from pre-UGS to post-UGS I wasn't concerned about any real effect on the front end resistance change on the overall sound of the system. If anything, the increase in the input impedance in the preamp would make it an even easier load for my sources to drive. So my preamp has a "minor" gain reduction in it compared to before, but apparently with no significant impact to the sound (if anything the preamp is even quieter than it was before).
As an aside, I've been a skilled listener for going on 30 years now, and I've heard just about everything there is to hear in what my and other systems can do. I know my own system
very well and can pick out the tiniest differences usually pretty quickly (but not always).
After the first 20 hours of listening to the Double+ I stopped paying attention to it. I had already been communicating with other Double+ owners who independently confirmed that I would need at least 100 hours on the amp before everything would settle out. I let it play to get past the 100 hour point literally without being in the same room, so as not to be influenced any further by what I had heard. What I heard when I came back was very much improved over what I heard when I first got the amp, so that much was proven out.
Music used for listening was as follows:
Bill Evans Trio - At the Montreaux Jazz Festival, Verve Master Edition
"One for Helen", "A Sleepin' Bee", "Mother of Earl"John Tropea - NY Cats Direct, dmp
"Moroccan Nights"Dianne Schuur - Deedles, GRP-D-9510
"The Very Thought of You", "I'll Close My Eyes"AK&US - Live, Rounder SACD/CD, CD Layer used
"Let Me Touch You for a While", "Choctaw Hayride", "Ghost In This House"Dvorak Overtures, Chandos 8453
"In Nature's Realm"Dire Straits - On Every Street, WB Records, @1991 release
"You and Your Friend", "Iron Hand"Arturo Delmoni - Violin Works, John Marks Records #14, Gold release
VariousRickie Lee Jones - Pop Pop, Geffen, @1991 release
"My One and Only Love"Arne Domnerus - Jazz At the Pawnshop, AudioSource Limited Edition
"Limehouse Blues"Mahler - Symphony No. 5, New Philharmonia Orchestra, Sir John Barbirolli, EMI Classics
Dvorak - Symphony From the New World, Chicago Symphony Orchestra, Sir Georg Solti, London
For anyone who looked at my systems specs, please note that all critical listening was done (and always is done) using my transport into my DAC.
Okay - anyone who gets this upgrade should basically ignore the amp for at least 100 hours. I'm saying this publically but two others told me the same thing privately when I first got the amp back. Take it as truth. I went through EXR5 to Ultra to Double+, and the EXR5 to Ultra did not have as significant a change in the first 100 hours as to this upgrade. Yes, I did the same kind of "ignore for the first 100 hours or so" when I got the Ultra, but it remained very close to as delivered. The Double+ had some very good things to say on first listen (see the thread listed above), but it also sounded a bit rough and way too heavy in the low end. Yes, this upgrade really does improve the low end, giving it greater weight and presence. But until you give the whole amp a chance to even itself out it will sound too tilted in that direction... the high end will sound like it's suffering as a result.
However, here's what the Double+ amp did from the get-go that just got better with time - greatly improved clarity from the extreme low end through the mids and low treble. Greatly improved extension in the extreme low end, which I find hard to understand. It's not like the Ultra didn't go as deep strictly from a frequency response POV, so maybe the improved clarity improves the "presence" in the extreme bottom end. Greatly improved leading edge transient attack. The music really "pops" more than it used to - especially present on strings / piano. Lastly, acoustic performances sound much more real, even compared to how they sounded before – which was pretty darn real IMO.
Let’s talk about the changes to the high end for a moment. I use "In Nature's Realm" as a test for back of the orchestra resolution. In the piece there are a number of small strikes on a triangle which gradually become continuous as the music reaches a crescendo. With my old setup I could clearly hear the triangle and could picture it behind my right speaker. On first listening to the new amp I could barely hear the initial strikes, and the continuous run was at nowhere near the same level of clarity. It sounded almost muffled. After walking away for a hundred hours then coming back, the amp balanced out to where the triangle regained its presence and energy and if anything sounds now almost "meaty". And this I think is where I may have one area of concerned comment with this upgrade.
Maybe it's because of the improvement in the low end of the amp, but now I get the sense that the music doesn't - when it did before in the past - "float" upwards above the speakers to quite the same degree as before. The Dvorak mentioned above is one example. While the triangle seems to have the same energy it did before (maybe even a bit more), pre-mod the triangle when struck sounded "airier" and just sort of lifted itself gently above the tops of the speakers. Now it seems more firmly rooted to where it came from. There are other examples - a couple of moments in "You and Your Friend", a number of prominent moments with the harp in "The Very Thought of You", "Moroccan Nights". All have moments where in the past the high end excursions would seem as though they were gently launching themselves upwards and were extending to the ceiling. Right now, like I said, the energy seems to be there in spades but (if I had to guess) it's like the resolving tails are being truncated. It's equally possible that the improvements in the low end presence are just shifting the balance psychologically... to where everything just sounds “meatier” than it used to (that’s the best word I can use). It's also possible that this will get better with time - on first turn on there was no air
at all in the high end. This did improve to where it is now. I don’t know.
I have one other note here. While the clarity is tremendously improved as stated, for some reason I get the feeling the front-to-back soundstaging is not as deep as it was. Most noticeable on small jazz groups like the Evans and Arne Domnerus. When all the instruments are playing with moderate to high energy I get the transparency, but also an odd sense that they're all sort of falling more on top of each other from front to back. I know it sounds like these two things are in conflict, but believe me they are not. Imagine listening to a piano backed by a double bass through a bit of haze, but with about 8 feet between them from front to back. Now imagine the same thing, but without the haze, and this time with only about 3 feet between them. A byproduct of the improved clarity? A bit less of a "finesse" to the presentation? I don't know.
This time around I'm wondering if Frank's upgraded design actually will require significant amounts of time to really show what it's made of. I don't seem to recall needing more than that for the Ultra upgrade, but in this case if that's true I'll be ignoring the amp for the next 100 hours or so. Based on what I've heard so far am I happy I got the upgrade? I think so.
The improvements really are significant. My wife, who I trust as an independent listener (she likes listening to music but has no care whatsoever for the equipment, cables, or anything else) heard the same things at the outset and after we came back together post-100 hours (and you can believe me or not, but I never prompt her or try to influence her impressions). When I asked her if it now sounds better than it did pre-mod,
she said it was clearly better even while agreeing with me slightly on the high frequency stuff.
Frank and I have discussed my system particulars via email, and he has some strong opinions about what I should consider changing. At this point I'm neither agreeing nor disagreeing; I'm still in the process of figuring out if I'm really missing anything I used to have in my listening sessions.
Readers of this post should not assume I am unhappy here. Things really do sound better than before the mod! But unlike the Ultra mod I'm finding myself now being
much more critical during listening than before. So (and I hope Frank you realize I’m being completely objective here) I am left with three questions:
- Has the Double+ mod brought its improvements with some changes that I wasn’t expecting?
- Has the Double+ mod brought improvements at the expense of some “finesse” or “air”?
- Has the Double+ mod just exposed more of the limitations of my own system / recordings?
