I mentioned in another thread that I had picked up a Grant Fidelity TubeDAC pre-amp a while back and finally gotten around to hooking it up. It meant I could use the S/PDIF output from CD player rather than analog, and the TubeDAC replaced the pre-amp stage from HK 3270 receiver which I had been using previously.

I was on a customer call until ~1AM last night and having trouble getting to sleep, so figured I would listen to some music and read some technical documentation (guaranteed zzz). Listening to a Pink Floyd live album (Pulse I think), "What do you want from me".

The song started normally, but when the organ started I sat bolt-upright... the sound came from not just beside me but a little bit behind. I had noticed earlier that something seemed different about the soundstage / imaging after switching hardware, but my first impression was "maybe a bit less tight for point sources"

I hadn't heard anything like this for >20 years (better audio equipment, not better drugs).

After some component swapping I found the following:

- going from M3 to M5HP made a big difference - imaging on the M5's seems comparable to the Sierra-1's, which in turn had the best imaging of any speaker I had heard recently

- switching between line-out and tube-out on the preamp made a smaller difference - from "beside and slightly behind" to "beside and slightly ahead"

- there was a bigger difference between "analog CD going through HK3270" and "SPDIF CD going through TubeDAC line out"

Each step seemed to add a small improvement. The overall result though was pretty impressive - decently tight imaging of point sources like higher pitched drums but the kind of "sound all around" that you would normally only get with surround speakers.

One of my early thoughts was that the tube output might have put the channels out of phase, but I didn't hear the usual "sounds appear just outside the speakers and your ears feel stressed" effect... plus normal recordings still had normal soundstage.

>> there was a bigger difference between "analog CD going through HK3270" and "SPDIF CD going through TubeDAC line out"

And yes, the obvious split-the-difference test would have been "analog CD going through TubeDAC line out" but I ran out of time. Will try that tonight.

OK, that was interesting. No more testing different configurations yet, but played another few CDs while working. On Sheep from Pink Floyd's "Animals" I realized what was different with the sound...

Sheep opens with electric piano and sheep noises, followed almost immediately by bass guitar. The bass is sharply located in the center, while the electric piano has always sounded "out of phase" and smeared across the soundstage with most of the sound seeming to come from a bit outside the speakers.

With the new setup the electric piano was sharply located "over there", off to the right somewhere between 30 and 40 degrees, almost twice as far from the center in terms of angle as the right channel speaker.

There was still some piano sound coming from near to (and just outside of) the left channel speaker but I can't rule out the possibility of the asymmetric room turning what should have been another sharply located piano sound on the left into a mostly one-sided result.

This effect only appears on albums which have had obvious audio effect processing - on all of the other tracks the instruments are placed between the speakers, and if anything the soundstage seems to extend beyond the speakers a bit less than I remember before (although it's possible that the "slightly outside" tracks are now the ones where I am hearing that "way the heck outside" effect.

Interesting stuff.

Sounds to me like a pretty awful DAC inside your CD player. Never had any problem like that, but then again, when I was using my CD player back in the day, I went out and bought based on the best DAC out there. Arcam Alpha7se .. that was all i could afford. Would have loved to try the alpha 9 ring dac to see how they sounded, but never had the chance

Hmm, good point. The whole player (200 disk carousel) was ~$200 CDN

All of the components in the chain seemed to make a slight improvement but the one step I haven't isolated yet is going from internal DAC to S/PDIF + external DAC (in the TubeDAC).

Before this I had no idea what to expect from changing DACs and associated circuitry.

Yep, you were right... I tried a few different configurations until I ended up with the original setup (HK3270 phono / tuner / preamp feeding Adcom 555 power amp) but with CD carousel SPDIF'ed into TubeDAC and line out from the DAC going into 3270 CD input.

Along the way I tried phono -> HK3270 with Tape Rec Out feeding Line In on the TubeDAC connected as pre-amp... but it didn't sound very good. I realized afterwards that I had played a couple of albums I haven't heard for a while, which was stupid.

Anyways, thanks for the tip about the DAC. I had not really thought of DACs as things with distinct sounds. Digital in -> analog out, how hard can that be ?

So I found some of my missing soundstage.

Around the same time I switched from receiver-as-preamp to tubedac-as-preamp I also did one more comparison between M5HPs and M60v4s. I still like the M5HPs better (and one day I hope to have time to finish that $%%# switch box so I can describe the difference better) but that's not the point. The point is that after finishing the testing I moved one of the M60s well away from the listening area but didn't have room for the other so turned it sidewards and left it between the M5HPs, close to the right speaker, back at least 6" from the fronts of the speakers.

After switching to the tubedac as pre-amp I noticed what seemed like a dead spot in the soundstage between the speakers, with the sound biased to the left a bit. I switched back to the HK receiver as pre-amp and still wasn't happy.

Last night it occurred to me that the "dead spot" in the soundstage more-or-less corresponded with the location of the M60. Dragged it out of the listening area and the dead spot mostly went away (I guess this is where the advice about not putting your electronics etc... between your stereo speakers comes from).

There is still a noticeable difference in sound between the two preamps, with the HK3270 sounding more natural to my ears and the TubeDAC sounding a bit darker or maybe duller. Interestingly enough switching between the HK3270 amp and Adcom amp has the opposite effect, with the HK3270's amp weaker in the bass and duller as well.. suggesting that the amp and pre-amp cancel each other out a bit. Leaves me wondering which one is closer to "right".

I guess this is how you end up living on CanuckAudioMart or Audiogon buying and selling audio equipment trying to get a handle on what each option sounds like. Starting to realize why the "internet herd mentality" is so popular -- where someone on the internet decides what "the very best product is" in a category, discussion ensues but reaches resolution, and everyone just goes out and buys it.

One more update...

Over the last month or so I had been becoming more and more unimpressed with one aspect of the sound I was hearing. The imaging for "normal" albums (where "normal" in this case means "most of the recorded sounds are between the speakers rather than being manipulated to be far outside the speakers") just wasn't as good as I remembered it being in the past.

It's hard to describe what was missing - instruments & vocals still appeared at different points across the soundstage as they should - but the imaging wasn't as "sharp" as I remembered.

In the end what I found was that switching from tube-out back to line-out on the TubeDAC pre-amp restored the imaging to what I expected. At that point I remembered that during earlier testing between line-out and tube-out I hadn't been sure which to go with, but ran out of time for experimenting and left it wired to use tube-out (which is basically line-out plus a unity-gain tube buffer).

So where this leaves me is that rather than using the TubeDAC to play with "tube sound" I am using it to get a better DAC than what I have in the CD carousel. So not what I planned but still good.

Cool result. It's hard to quantify or describe the audible subtleties you are describing. We can all relate that when it sounds great Mr Burns kicks in.

"I'd trade it all for a little more!"

I know your setup is in a large open room. If you are interested, you can improve things further by placing gobo panels on either side of your loudspeakers. This can simulate symmetrical boundaries -really important for channel balance and proper stereo imaging. Even better would be QRD diffusers instead for your wide dispersion Axioms.

Try it with couch cushions or draping fabric over chairs backing against the speakers at sides. Kinda neat how you can manipulate sound this way.

Interesting... will give that a try. Are you thinking "close to the speakers" or more like what "on the walls" would be if I had a wall on both sides ?

Surprisingly the difference was not all that subtle... imaging went from "OK I guess" to "quite good" with just that one change.

I am going to try to either build or source some kind of diffusion over the winter. I picked up a calibrated Dayton mic to go with the 2i2 A/D converter so will try to get REW running before I mess with room treatments much more.

That way I can imagine I see changes as well as imagining I hear them

The closer you put them the more dramatic the effect. Within a couple of feet to the sides should do. You are kind of simulating a first reflection point when you do this so think of angles to your mlp. It's a trick they sometimes use in high end stores when they cant give a speaker demo a separate room.

REW is a great program and its not really difficult to get up and running. It helps visualize what your hearing. The hard part is interpreting the graphs, thankfully the author is active on the forum and will look at your graphs along with other experienced people on the forum so you too can be an expert. You will loose many hours of your life during the winter messing with this. I have used it to compare my Dirac before and after corrections strictly out of curiosity. Prepare for some real brain overload, though i suspect its not as bad for people who are much smarter than myself. Have fun

For a while i was following the MDAC thread on Pinkfish until it just overflowed my mind on info/gobbletygook. Now I just realize that my hearing it just too shot to really appreciate what the audiophiles do.

That worked surprisingly well. The two panels need to be *exactly* the same distance/angle from the speakers or it doesn't work, and I had to remove/hide most of the other treatments to prevent the sound from being too "dead" (including raising the cellular blind on the nearby side window), but the difference is significant:

- imaging is a bit tighter, but it was pretty good before... the big change is not so much with the main sound sources but the "background" sound (presumably echoes etc... both on the original recording and from the room) is much more consistent

- the "background" improvement seems to be enough to help with perceived realism of instruments, to the point where the brain conjures up a real instrument much more frequently than before (I'm not describing this well, but it's like you can almost see the instrument in front of you)

- phase-shifting sound effects where the background seems to swirl around are much more prominent (this is one thing current room/equipment had been missing)

- I finally found the point where even I think "that's too damn ugly for the living room"


You used two words I had not heard before - MDAC and Pinkfish - so I had to go look them up

There certainly is a point of diminishing returns and I feel like I'm getting fairly close to that point myself (at least until I listen to LFR's) but the good news so far is that while my hearing is probably equally shot (or worse) I am still finding that I can recreate most of the aspects I really liked about the better sound systems from 35-40 years ago.

Fortunately I never made it into serious audiophile territory back then (other than hanging out in the $100K system listening rooms until the salesmen asked me to leave) so hoping I won't have to go there now either.

AFAICS the limiting factor in my listening environment is now the big cushy arms on my listening chair. If I lean back in the chair the imaging is really blurred, but perching on the front edge of the seat brings it all back. Even after all these years I'm still being surprised by how much difference the environment makes.

If I can put off messing with REW until the gloomiest part of winter I will consider that a great success.

When you shorten your acoustic space's initial time delay gap to less than the delay in the recording you perceive the acoustic space in the recording as your own.

Hint!

REFLECT !

Thanks. I'm fighting some kind of cold/flu thing right now and brain not working but will think about that when my thinker starts working again.

I think it argues for headphones... or really big recording studios

I've been to Prince Edward Island. Dirt is red.

Potatoes were good!

PS. Feel better Bridgman!

Sure. With headphones the issue is completely bypassed.

Once you get into REW you might find your subjective impressions of what you like don't match how your room "should" measure. Don't worry about that stuff. It's more rewarding to correlate your subjective likes with measured results as a baseline. Then when you change something, and measure it, you can try to understand the technical reasons for your new subjective impression and really hone in on refining that part.