2. amps-preamps
  3. 1135309079

Newbie Tubie just wants insight and direction....

Hi All and Happy Holidays!
I recently acquired a used Antique Sound Lab 1001dt, it's not the newest version with remote but it does have the built-in bias meter (thank God for this!).

I've recently come over from the SS camp owning a B&K AVR 307. What I'm noticing, and this is only 2 ch vs. 2 ch for the B&K vs. the ASL, is that for HT/movies, I don't get a good center image. I've checked all the settings on the 999es to make sure that it's in downmix 2ch. mode/analog only out so basically I'm only swapping out the amplifiers.

I get a great center image with the B&K but with the ASL the sound seems to be coming from just left and right...not "transparent" if that's the right term. Voices just don't jump out from the middle of the screen as it does with the B&K.

Now, as far as music goes, it's a totally different story, it's HUGE and lucious, velvety and "easy" but there are still some times when I feel that the music doesn't have the proper staging or imaging conjuring up one large ensemble out in front of me or to the center.

Is this just an "experience" of moving from SS to Tube gear or do you think there may be other issues to deal with.

For all purposes I've included all equipment relative to this question below.

Thank you in advance for any insight or advice, tips or tricks...again, Happy Holidays!

Your new tube rig advocate!

Current equipment:
Marantz 63se
Sony 999ES for SACD and HT duties
ASL 1001dt integrated (JJ Tesla kt88's stock 12au7's)
Paradigm Reference Studio 20's V.2's
Silent Audio Apollo C's (the silver ones, can't remember whether these are the C's or the A's)
Signal Cable Bi-wire
Signal Power Cord

I have other equipment but I'll focus on these for now since my question really pertains to 2 channel.
auditude
bignerd100
515 posts
 
Rwbadley,
No tongue-in-cheek. Most tube amps do not invert the phase of the output signal in order to simplify the circuit. The positive and negative taps are correctly positive and negative but the signal is 180 degrees out of phase. THe easiest and most efficacious way to get things in line is to swap the +/- at either speaker or amp end. If your preamp has a phase inversion feature (as Clio09's does) you can use that instead.

The manual for Auditude's ASL should state if this is the case with his particular amp. If it doesn't then I guess that most flawed of instruments must be employed,... the human ear.

Good luck!
auditude OP
10 posts
 
If I were experiencing "out/reversed" phasing wouldn't I also notice a lack/cancellation of bass and mid-bass performance?

I am experiencing wonderful and glorious amounts of bass, though not as "tight" and controlled as my B&K it is there in spades compared to my SS gear. Funny as I thought that this may be the area where I'd be at a loss when going from SS to tube. Happily, I am no where near at a lack of bass. (I'm attributing this to the "harmonics" of the ASL running in triode mode. It's not as prominent running pentode).

At any rate, back to my question, "Wouldn't I notice lack of bass with reversed phase?" as each side would theoretically "cancel" eachother out and I would hear a hole in the lower freqs.

I'm only familiar with that occurrence due to calibration of my subwoofer previously with the ss gear. 85% of the time my sub is off as I am truly a 2ch. guy at heart and these lil' reference 20's punch you in the gut with the ASL.

Please let me know if I am incorrect in my above statements.

Thank you again for the tips and suggestions!
bignerd100
515 posts
 
You would not neccesarily have a lack of bass. Bass would be cancelled out if ONE speaker were out of phase. The lack of bass when phase is inverted is often the case but not always. The easiest way to find out is to invert the phase.
dan_ed
2,451 posts
 
Assuming your phase is correct, I would suggest looking at rolling in some different tubes, especially the 12au7's. Maybe just the thing to get the imaging you're looking for.
auditude OP
10 posts
 
Eureka! I've found the culprit! I sat down and did a level calibration with my ratshack spl meter and found that the right side was 4.5db's louder than the left!

I had the 999es set-up menu and ran the internal test tones with trusty spl meter in hand and lo and behold 4.5db's in variance!

Well, for now, I've set the 999es -4.5 db's on the right channel but long term what can I do? If I'm running my 63se I don't have this luxury.

Replacing internal parts are not the easiest of options but I'm considering checking the resistors and "freshening" up the guts.

Any other thoughts to remedy this 4.5db in difference?

TIA have a safe and happy New Year!
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