bowtie427ss
Lunatic Member
Holy crap GDM! Godspeed to you mate. Here's to hoping all scans bring good reports.
I know from experience that i don't have to tell you to take it slow and easy, your injury is doing a fine job of that, and i'll try not to post any "side splitters" for a while.
I know from experience that i don't have to tell you to take it slow and easy, your injury is doing a fine job of that, and i'll try not to post any "side splitters" for a while.
jaaronb
Active Member
No worries at all! Reminds me I have a nodule I need to get checked that turned up during a lumbar MRI a few years ago. The referral for the nodules is a CYA/SOP...they refer everyone with appearance of one to avoid malpractice lawsuits down the road. They're common and extremely rarely anything to worry about.
That broken rib though - hope you have a speedy recovery. I know from experience how painful those are!
jaaronb
Active Member
I just spoke to Bill at Great Plains Audio. They took a close look at the 806as, tested them, regaussed, and have not been able to find anything wrong with them or to replicate the distortion. He said they look pristine.
So the question is obviously...what could be causing it? I've never heard this kind of distortion from my system before - it only occurs in a narrow frequency band and is only particularly audible during quiet passages during which those frequencies are prominent, e.g., a quiet trumpet solo. Obviously the first thing I'll do is switch the drivers to opposite channels - I stupidly did not do that before sending them off because the nature of the distortion sounded so mechanical - rather than electrical - to my ears.
It almost sounds as though there is a vibrational quality to the distortion.
The distortion is such that you can still hear some of the source tone that is causing the distortion, but not much, and it is more of a true distorted sound, rather than static or electrical noise being introduced.
I really hope Bill is right, and it isn't the compression driver, but what worries me a bit is that the distortion seemed to become slightly more noticeable and perhaps louder after I cleaned the voicecoil gap and reseated the diaphragm.
Anyway, assuming Bill is right, and upon switching the CDs to opposite channels the distortion remains on the left side (and does NOT follow the driver in question), to me the next most likely suspect is the crossover, especially given that I made them.
Does the nature of the distortion I'm describing sound like something that could be caused by a faulty cap? Or a bad inductor? Poor soldering? A broken wire inside the sheathing of the inductor input/output leads? (this seems a possible suspect come to think of it...portions of the inductor lead wires were stiff to the point of feeling hardened or brittle (although they did not crumble or anything).
Anybody ever heard this kind of distortion from a compression driver before? Anybody have a guess? The caps are all new, I'm using the original inductors. I did not have the 30923 networks installed during all this. As always, I'd appreciate any help or guesses - educated or otherwise!
gdmoore28
Super Member
Aaron, I'll bet your crossovers are fine. Maybe somebody will correct me, but I can't conceive of anything in the crossover that would cause distortion in only one single frequency range. You'll be able to test this once you get them back and see if the problem is still there. If so, swapping sides will tell the tale.
The other day when I was doing my testing I thought I could detect a similar distortion from my horn. I used the old mechanics trick. I used a stethoscope to trace the distortion to a mechanical rattle being induced by the cabinet.
The other day when I was doing my testing I thought I could detect a similar distortion from my horn. I used the old mechanics trick. I used a stethoscope to trace the distortion to a mechanical rattle being induced by the cabinet.
jaaronb
Active Member
Thanks for that GDM... I couldn't think of anything that would introduce it in the crossover either.
It *seems* to be coming directly from the mouth of the horn. I had the bug guy who happened to be there tell me what he heard and he heard the same thing.
Could it be caused by the horn being too loosely bolted to the compression driver body? I can't imagine it could.
Really hope I don't have to send it back again, but then I don't want to chase a phantom distortion pattern back through my crossovers either. Bill is aware of what the issue was, and swept it with test gear, and was unable to find anything wrong with it or replicate the issue.
Like you said, the simple swap will tell the tale.
elitopus
Addicted Member
I have also heard this distortion before. On my last setup with large format horns. I only noticed it on certain songs and certain frequencies. Especially stuff like piano or classical music.
I took the drivers apart to look for any defects but could not find any. I have had diaphragms come apart before, and the usual junk in the gap. That wasn't the case with these drivers.
I would do a sweep on those drivers and not be able to duplicate the distortion. It was on both drivers, but more on one than the other. It was such a pain to move them around that I never swapped them from side to side.
Horns (and Altec especially) are so reveiling of any flaws in upstream components. I just recently replaced my CD player because it was causing a hiss in one channel. Also the balance seemed off. I don't think its something like that, that is causing your problem but you never know.
Like was mentioned above, you might have a horn that is vibrating against the cab at a certain frequency. Or something like that.
Have you listened to your problem song with the 806 driver not attached to the horn?
I took the drivers apart to look for any defects but could not find any. I have had diaphragms come apart before, and the usual junk in the gap. That wasn't the case with these drivers.
I would do a sweep on those drivers and not be able to duplicate the distortion. It was on both drivers, but more on one than the other. It was such a pain to move them around that I never swapped them from side to side.
Horns (and Altec especially) are so reveiling of any flaws in upstream components. I just recently replaced my CD player because it was causing a hiss in one channel. Also the balance seemed off. I don't think its something like that, that is causing your problem but you never know.
Like was mentioned above, you might have a horn that is vibrating against the cab at a certain frequency. Or something like that.
Have you listened to your problem song with the 806 driver not attached to the horn?
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jaaronb
Active Member
No I haven't tried listening without the horns. GPA shipped them back today, so I should have them Monday at the latest...I'm anxious to get them and see if the issue persists.
We're you ever able to get to the bottom of the issue with your last drivers?
You're right about how revealing the Altec compression drivers are. The issue I'm hearing could absolutely be caused by something upstream.
It does make me feel a little better to know someone else has heard a similar issue.
macaltec
Metal Master
I experienced basically the same thing with both my Cornwall II's and Heresy II's while playing Nora Jones, "Turn Me On" and Cowboy Junkies, "Cold Tea Blues". I have found that " Cold Tea Blues" is very good for finding weaknesses in setups. Swapped speakers and it didn't make any difference. Swapped amps, went from a Pioneer SX939 to an H/K Citation 19, problem solved. It may not fix your problem but it is worth a try.
elitopus
Addicted Member
+1
Start swapping things around. For me it could have been my CD player. Looking back I wish I would have tried that.
There is lots of talk about mass loading. Some people even mass load their speakers, crossovers, amps, preamps, and even CD players! Seems like some designs need this or benefit from it more than others.
And maybe component flaws starts to show more when playing Altecs at 100+db's
Start swapping things around. For me it could have been my CD player. Looking back I wish I would have tried that.
There is lots of talk about mass loading. Some people even mass load their speakers, crossovers, amps, preamps, and even CD players! Seems like some designs need this or benefit from it more than others.
And maybe component flaws starts to show more when playing Altecs at 100+db's
jaaronb
Active Member
Yep... The volume issue did occur to me... but I don't think I've had them above ~95db peaks... Usually listen in the ~77 -83db range.
Don't worry... If the distortion is still there, first thing I'll do is make a YouTube video of it... even if it's mainly to assure myself that I'm not crazy.
I was hoping they'd arrive yesterday, since FedEx home delivery runs on Saturdays, but no dice. Hopefully tomorrow!
Don't worry... If the distortion is still there, first thing I'll do is make a YouTube video of it... even if it's mainly to assure myself that I'm not crazy.
I was hoping they'd arrive yesterday, since FedEx home delivery runs on Saturdays, but no dice. Hopefully tomorrow!
jaaronb
Active Member
Hey guys - got the 806as back from GPA and wanted to report back.
... The distortion I was hearing over a narrow frequency band is... Totally gone.
Called Bill at GPA to let him know of this outcome. He was a bit surprised, but said he hadn't been there to check them out when they first came in. I reminded him that after I cleaned the voicecoil gaps on both - before sending them off - upon reassembly the distorted driver sounded worse - more pronounced distortion on more passages that was more noticable.
FWIW, anyone listening to these or other Altec drivers should drop the nominal $70 bucks roundtrip trip to have them regaussed by GPA.
They sound noticably smoother across the HF band than before. I guess I was expecting the regauss to give them more HF punch, but in fact, the opposite seems the case. They are more refined and consistent across the HF band than before. Much smoother and more revealing.
FWIW, I think the issue was in how the diaphram in the bad driver was seated.... No big surprise that I reseated it worsely than it had been seated in the first place, causing more mechanical distortion than before. No telling how long since they had been used regularly before I got them, but OH MY GOODNESS they sound fantastic now.
I'm gonna go solder up the 30923 networks now.
I was not expecting the 3uf Jensen PIO caps I got for the 30923s to be roughly the size of a smoke grenade....
... The distortion I was hearing over a narrow frequency band is... Totally gone.
Called Bill at GPA to let him know of this outcome. He was a bit surprised, but said he hadn't been there to check them out when they first came in. I reminded him that after I cleaned the voicecoil gaps on both - before sending them off - upon reassembly the distorted driver sounded worse - more pronounced distortion on more passages that was more noticable.
FWIW, anyone listening to these or other Altec drivers should drop the nominal $70 bucks roundtrip trip to have them regaussed by GPA.
They sound noticably smoother across the HF band than before. I guess I was expecting the regauss to give them more HF punch, but in fact, the opposite seems the case. They are more refined and consistent across the HF band than before. Much smoother and more revealing.
FWIW, I think the issue was in how the diaphram in the bad driver was seated.... No big surprise that I reseated it worsely than it had been seated in the first place, causing more mechanical distortion than before. No telling how long since they had been used regularly before I got them, but OH MY GOODNESS they sound fantastic now.
I'm gonna go solder up the 30923 networks now.
I was not expecting the 3uf Jensen PIO caps I got for the 30923s to be roughly the size of a smoke grenade....
elitopus
Addicted Member
That just means they are good
And hey I am glad you got your driver issue sorted out. I agree that GPA does a hellava good job.
Valveglow
Super Member
Thanks much! Not yet, but I am sure to be coming up with a few. I'm a JBL guy who has recently become fascinated with building an Altec 19 type speaker and also, I will be inheriting some 414Z woofers, as well as a couple of compression drivers. Thus far, I have three 811b horns, so I am certain I will need to construct something before too long!! If you don't mind, when I have specific questions, I will look you up, as my knowledge on this is hovering near zero...
Thanks again!!