driver rattling from millett
Apr 21, 2006 at 2:23 AM Thread Starter Post #1 of 26

seanohue

500+ Head-Fier
Joined
Jan 11, 2006
Posts
755
Likes
10
Ever since I stepped my voltage up from 17V to 24V, I've been getting a static (not really rattling i've decided) noise in the drivers of both my 325i's and HD555's. Is this normal at higher voltages or could there be a problem else where? My bias is at 10 and the amp gain is whatever the default value is, I'm using BUF634P's. The noise only happends at certain frequencies, like a low power chord on a guitar or something, so its a little annoying while listening to metal. It's not just limited to the poor quality songs either, it persists in lossless and AAC 320kbps files.
 
Apr 21, 2006 at 2:49 AM Post #5 of 26

seanohue

500+ Head-Fier
Joined
Jan 11, 2006
Posts
755
Likes
10
Im still using a TREAD, but I changed the input wall wart. Instead of the 24VDC 100mA outputting 24VDC, im using a 24VAC 450mA outputting 24VDC. The 24VDC wall wart was set a 24VDC output, but when it got to the amp, the voltage dropped to 17V once the amp was turned on.
 
Apr 21, 2006 at 2:54 AM Post #6 of 26

n_maher

Resistorous Conflagorous
Joined
Nov 20, 2004
Posts
8,405
Likes
31
Quote:

Originally Posted by seanohue
12AX7 and its in both ears.


Please tell me that you meant to type something different there...
 
Apr 21, 2006 at 3:04 AM Post #7 of 26

seanohue

500+ Head-Fier
Joined
Jan 11, 2006
Posts
755
Likes
10
Yea i did, AK just pointed out that 12AX7s cant work there, and I don't know why I thought I was using them. I checked my tubestore order though and they are in fact 12FK6.
 
Apr 21, 2006 at 3:13 AM Post #8 of 26

n_maher

Resistorous Conflagorous
Joined
Nov 20, 2004
Posts
8,405
Likes
31
Have you checked the headphones for loose hair? If there's some resting against the driver it can cause the symtpoms you describe. Also, have you checked the voltage that the TREAD is outputting under load? If you're using a 24V DC wallwart (like it seems you are) and you're using a stock TREAD config (board fully populated) it's possible the voltage at the tubes is too low and the amp still isn't working properly.
 
Apr 21, 2006 at 3:33 AM Post #9 of 26

seanohue

500+ Head-Fier
Joined
Jan 11, 2006
Posts
755
Likes
10
Nah, I had that problem last time. The new transformer reads 24V when the amp is both on and off. I haven't checked the drivers because I dont know how to take apart the HD555's and I cant get the 325i open.
 
Apr 21, 2006 at 3:41 AM Post #10 of 26

seanohue

500+ Head-Fier
Joined
Jan 11, 2006
Posts
755
Likes
10
im gonna give my ears a rest for a few days to make sure that the listening volume isn't causing the problems. thanks for the help though
smily_headphones1.gif
 
Apr 21, 2006 at 12:35 PM Post #11 of 26

n_maher

Resistorous Conflagorous
Joined
Nov 20, 2004
Posts
8,405
Likes
31
Quote:

Originally Posted by seanohue
Nah, I had that problem last time. The new transformer reads 24V when the amp is both on and off. I haven't checked the drivers because I dont know how to take apart the HD555's and I cant get the 325i open.


Where are you taking this reading from? I'd suggest taking a reading on the board at the switch position or somewhere like that. If you're only getting 24V from the wallwart under load you're probably on giving the Millett 22V or less, which could cause issues.
 
Apr 21, 2006 at 5:19 PM Post #12 of 26

Gontran

Head-Fier
Joined
Dec 24, 2005
Posts
63
Likes
0
Quote:

Originally Posted by seanohue
.... im using a 24VAC 450mA outputting 24VDC....


I hope that's a misprint? The obvious answer is that it wouldn't work if it were 24VAC. I don't know enough about your p-supply, but if it has an input protection diode, you could be feeding it with 24V pulsed DC...

Do you have access to another similar set of phones?
Can you feed your amp a sine wave and observe the output with a scope?
 
Apr 21, 2006 at 6:46 PM Post #13 of 26

BradJudy

500+ Head-Fier
Joined
Jun 26, 2003
Posts
848
Likes
10
Quote:

Originally Posted by Gontran
I hope that's a misprint? The obvious answer is that it wouldn't work if it were 24VAC. I don't know enough about your p-supply, but if it has an input protection diode, you could be feeding it with 24V pulsed DC...


He's running 24VAC into a TREAD which is presumably populated to handle the rectification and smoothing.
 
Apr 21, 2006 at 9:45 PM Post #14 of 26

seanohue

500+ Head-Fier
Joined
Jan 11, 2006
Posts
755
Likes
10
I'm taking the reading at the leads on the DC input jack. Yes, the TREAD has the bridge rectifier in so it's outputting DC voltage.
 
Apr 21, 2006 at 10:25 PM Post #15 of 26

seanohue

500+ Head-Fier
Joined
Jan 11, 2006
Posts
755
Likes
10
I think the problem is the source. Everything is fine from my iPod to the millett to both headphones. I would've been able to test this last night but I just got it today. Thanks for the help guys
smily_headphones1.gif
 

Users who are viewing this thread

Top