Pinging Ethan Winer, et. al: what SHOULD the test tone sound like?

dogorman · « **on:** 3 Jun 2008, 10:44 pm »

I have downloaded the complete set of test tones from Mr. Winer's realtraps website, and just now played the 300hz sine wave for as long as I could stand to listen to it, which wasn't very long.

The thing I can't quite figure out is whether I was discomforted by the unfettered intensity of the sound, or if I was discomforted because the sound wasn't unfettered.

What I heard was a very "tubular bell" sort of note, accented by an overtone about a half-step lower in pitch and of a much dryer timbre, something not unlike what you'd hear if you'd mounted a very, very tightly sprung piece of tissue paper over the tweeters. The overtone also seems to wander in both pitch and intensity, particularly if I monkey with the volume on the preamp remote -- the overtone gets much stronger for a second or two after I adjust the volume.

I also tried the interesting (?) test of playing the same track in the DVD player, and I got the same result.

Are these the very sort of things I'd hear if I had a problem, or are they associated with having made the test cd on a computer dvd-burner, or is it supposed to sound like that?

dogorman · « **Reply #1 on:** 3 Jun 2008, 10:51 pm »

ADDENDUM:

I didn't type this before because I didn't believe it, but the PITCH changes as I raise and lower the volume. It gets higher if I lower the volume and lower if I raise the volume.

Please tell me that there's one, obvious, can't-be-anything-else explanation for all of this, because I'd planned to do a lot of other things this evening besides slitting my wrists....

AB · « **Reply #2 on:** 4 Jun 2008, 12:13 am »

I am not Ethan but I too have used the Real Traps test tones to drive myself crazy. And I have used them to sort out the usual room troubles in the process.

The tracks do not consist of one continuous tone. The tones last for 10 seconds and then increase to the next frequency for the next ten seconds. So track 29 is 290Hz for ten seconds then 291 for the next ten etc. until you reach 300.

Track 30 is pink noise.

So is that what you're hearing - the tone rising every ten seconds?

dogorman · « **Reply #3 on:** 4 Jun 2008, 12:21 am »

No, I noticed that too -- the pitch-changes to which I'm speaking are independent of the ten-second cutoffs. I know this must sound completely hallucinatory, but the pitch of the reproduced signal (and the overtone) actually change in the opposite direction as the volume.

I can't imagine that's right, and yet I don't really know for sure -- particularly since I don't have a reference for what the test tones are supposed to sound like.

AB · « **Reply #4 on:** 4 Jun 2008, 12:56 am »

You got me, then.

I used my computer speakers just now to listen to a few of the tones. Can you try that?

I can only imagine the tones are exciting some resonances either in your speakers or in your room.

I'd crawl around and see if I could find where these overtones are strongest.

dogorman · « **Reply #5 on:** 4 Jun 2008, 01:01 am »

I can eliminate the speakers from having switched-in a pair of different vintage and design. And I think I can also eliminate the room on the basis of having listened in the near field.

My thinking is that there's something internal to either the amp or preamp that's not behaving the way it should. If this was tube gear, I'd say I had a bad tube and it was "squawking," but seeing as how it's all SS, I'm not sure what the equivalent problem would be, or if there even is one.

JRace · « **Reply #6 on:** 4 Jun 2008, 03:26 am »

If you really want to know what a 300Hz pure tone sounds like go to your local hearing clinic and ask to hear the 250Hz tone (probably as close as they will be able to get).

It should sound like a solid tone, no pitch changes, no intensity changes.

mgalusha · « **Reply #7 on:** 4 Jun 2008, 02:08 pm »

If you can use your PC as a source Marchand Electronics offers a free tone generator for Windows. See this page.

It's not sophisticated but it works just fine. Try it with some headphones first to get an idea of what a 300Hz (or whatever) tone sounds like without room interactions.

As a side benefit, you can pretty easily figure out where your high frequency hearing drops off. Not with any kind of accuracy like a hearing specialist would offer but you can get a ballpark figure.

Mike

AB · « **Reply #8 on:** 4 Jun 2008, 03:11 pm »

Speaking of hearing tests...
This is fascinating.

http://www.phys.unsw.edu.au/jw/hearing.html

Sorry for the thread hijack.

Ethan Winer · « **Reply #9 on:** 4 Jun 2008, 04:05 pm »

Quote from: dogorman on 4 Jun 2008, 12:21 am

the pitch-changes to which I'm speaking are independent of the ten-second cutoffs. I know this must sound completely hallucinatory

You may not be hallucinating.

When a room resonance is near, but not exactly the same as, a frequency coming from the speakers, you'll hear what seems like a single note yet it's still out of tune. So this may well be what's happening. The best way to know for sure is to use our test tone CD as intended, and spend the half hour plotting each frequency. Then if you see, for example, a strong peak at 108 Hz (just south of an A bass note), you'll know that's the right explanation.

--Ethan

mgalusha · « **Reply #10 on:** 4 Jun 2008, 04:12 pm »

Quote from: AB on 4 Jun 2008, 03:11 pm

Speaking of hearing tests...
This is fascinating.

http://www.phys.unsw.edu.au/jw/hearing.html

Sorry for the thread hijack.

Nice hijack.

That is very cool. Sadly my hearing drops at about 14K, which isn't too bad for 48yo male but it would be nice to hear 16K again.

dogorman · « **Reply #11 on:** 4 Jun 2008, 07:00 pm »

Well, I'm essentially 100% convinced that it isn't the room. I can hear the same strange things happening in the very, very, very near field.

A member of another forum used the phrase "bad cap," which I was inclined to dismiss as a catch-all answer, but now I'm not so sure.

jneutron · « **Reply #12 on:** 4 Jun 2008, 08:58 pm »

Quote from: dogorman on 3 Jun 2008, 10:51 pm

ADDENDUM:

I didn't type this before because I didn't believe it, but the PITCH changes as I raise and lower the volume. It gets higher if I lower the volume and lower if I raise the volume.

Please tell me that there's one, obvious, can't-be-anything-else explanation for all of this, because I'd planned to do a lot of other things this evening besides slitting my wrists....

Listen to somebody singing with headphones on where you can also hear the music. If they have them loud, they will sing off key, in the exact same pitch change direction you noted.

Don't know why, but it does work. Figured it has somtin ta do wit dat coily ting in da eeeyaah.

Cheers, John

dogorman · « **Reply #13 on:** 4 Jun 2008, 09:23 pm »

Well I've got a problem than I'm relatively confident can't be explained by ear-response, most notably because it's intermittent.

I've had this persistent difficulty in the behavior of my gear for some time, now, and it's bad enough that non-audiophiles can hear it. I haven't been using the test-tones for long enough to say any of the following things about them, specifically, but with regular source material the problem has been...

a) unpleasant enough that my girlfriend can tell the difference
b) sometimes absent after powering-down and re-connecting everything
c) global to different source components
d) global to a different house, a friend's speakers and wall outlet
e) neither more or less likely during the day or night
f) not invokable by any known means if not already present by itself

At someone else's suggestion I just tried to run the test tone with two different pairs of speakers, and couldn't get any of the pathologies described in my OP to happen, with the original pair on which I'd been hearing all the problems yesterday.

In the meantime, Steve McCormack himself posted a reply in a different forum, in which he said, "That sort of problem isn't associated with electronics; it's your speakers."

To which I say, gosh, all four pair it's been detected on? Same exact problem?

Toka · « **Reply #14 on:** 4 Jun 2008, 09:58 pm »

Quote from: AB on 4 Jun 2008, 03:11 pm

Speaking of hearing tests...
This is fascinating.

http://www.phys.unsw.edu.au/jw/hearing.html

Sorry for the thread hijack.

When I went for a hearing checkup recently I showed that test to the audiologist and his assistant...big laughs all around. Fun to play with, though.

tgp06 · « **Reply #15 on:** 4 Jun 2008, 10:10 pm »

c) seems to eliminate a source as the issue. d) and e) make me think it's not a power issue (other than possible intermittant interference on your line from a refrigerator, air conditioner, etc). d) and your last statement leads me away from the speakers. There's not much left...preamp, power amp as major items. I know you've changed ICs at times, so I wouldn't suspect an issue there. I would try another preamp OR power amp in your system for awhile (being an intermittant problem you may have to listen for an extended period to either duplicate the discrepency or be certain the change fixed the issue). Change only one of those (pre or power amp). If the problem is gone long term, that is your problem component. If the problem occurs again, put your original back in (I'd say it's OK). If it's still an issue, do the same with the other item (pre or power amp).

dogorman · « **Reply #16 on:** 4 Jun 2008, 10:49 pm »

Okay -- I think I can persuade a buddy of mine to trade separates, one at a time like that.

Any reaction to the suggestion made by others that the symptoms don't support electronic problems?

tgp06 · « **Reply #17 on:** 4 Jun 2008, 11:14 pm »

Only to the extent that it may still be occassional pollution on your home power, but can't imagine how that do anything other than get louder or softer when you adjust volume. Seems like you've eliminated most things in your system, except the pre & power amps. The symptom doesn't seem consistent with motor interference/pollution- usually get a "hashy" sound, at constant freq- not a perceived frequency change related to volume.

JRace · « **Reply #18 on:** 5 Jun 2008, 03:28 pm »

Have you tried replicating the issue withonly one speaker playing?
What about with both speakers playing, and one out of phase?

When you say different pairs of speakers, do you mean another set, or different brand/model of speakers?

dogorman · « **Reply #19 on:** 5 Jun 2008, 08:05 pm »

The problem recurs with different brands and models of speakers. In particular, Linn Ninkas, Totem Mite-T's, Audio Physic Spark IIII's, and Linn Katans.

A late-breaking development: When the problem is occurring, I can feel what I always thought was a faint vibration on the front aprons of both the amp and preamp. When the problem isn't occurring, I can't feel the "vibration."

I hadn't thought much about it until last night, when I realized that I could still feel it after powering everything down -- which suggests that it's not a vibration at all, but a very, very faint electrical discharge, leaving the front apron of the two pieces and traveling down my hand into ground.

...unless I'm imagining that, too. At this point I have no idea what to believe, except that my very, very expensive rig sounds positively unlistenable, and I'm pretty-well exasperated with the whole flippin' thing.