Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › M³ Project Announcement
New Posts  All Forums:Forum Nav:

M³ Project Announcement - Page 18

post #256 of 565
11/22/04 at 10:51pm
Quote:
Originally Posted by morsel
The 8-pin TLE is a possibility. I took a quick look at the pdf and saw no info on proper use of Cnr, does anyone have a pointer on this?
Tangent's virtual ground writeup shows a schematic with a 1uF Cnr going to the negative rail:
http://www.tangentsoft.net/elec/vgrounds.html

Quote:
Originally Posted by ble0t
Perhaps a small cap from output back to CNR?
You'll see from the datasheet that doing that basically wraps a positive feedback loop around the TLE2426's internal buffer. I think it would make the TLE2426 unstable.
Reply
post #257 of 565
11/22/04 at 11:00pm
I stand corrected
Reply
post #258 of 565
11/22/04 at 11:11pm
My hunch is that you could also connect Cnr to the positive rail and the effect would be the same.
Reply
post #259 of 565
11/23/04 at 5:26am
Quote:
Originally Posted by Lil_JV
Is it okay if we just write M3 in the future? It is even easier than MMM.
Quote:
Originally Posted by morsel
M3 is a model of BMW. Why not just copy and paste M³ from a previous post?
Because
1) a google search on "site:head-fi.org m3" yields a lot of hits for a certain MP3 player
2) Micro$oft's file systems don't care much for superscript

- Eric
Reply
post #260 of 565
11/23/04 at 11:01am
Whoa...those posts are a blast from the past

More to the matter at hand, any updates/decisions?
Reply
post #261 of 565
11/23/04 at 4:30pm
Quote:
Originally Posted by ble0t
More to the matter at hand, any updates/decisions?
No, we're still waiting for more responses to trickle in. If there are updates we'll post them.
Reply
post #262 of 565
12/8/04 at 5:02am
Any updates?i'm looking forward to this design.
and i'm very glad to help you to do something useful.
Reply
post #263 of 565
12/8/04 at 5:19am
Quote:
Originally Posted by digi01
Any updates?i'm looking forward to this design.
and i'm very glad to help you to do something useful.
Thanks digi01. Morsel has gone out of town for a few days and has no email/web access. As soon as she returns I'll meet with her to discuss the open issues and I hope to order a couple of first-cut engineering prototype PCBs to build and test. We'll keep you all posted on the progress.
Reply
post #264 of 565
12/8/04 at 5:30am
OK,thank you.I am very interested in test it.

cheers
Reply
post #265 of 565
12/12/04 at 12:27am

start up pop

I just finished building PPA. And I'm really impressed with its improvement over my previous setup (CMoy and Szekeres). Thanks guys for your contribution. I'm considering taking a course next spring in analog IC design so I might be able contribute later to the society.

I was excited to find out this new M3 project coming up. Can't wait to build it.

I wonder if you guys could include some solution for the pop when the amp starts up.

It seems like the common solution now is either take them off the head or add another switch so that the headphone output could be turned on seperately to avoid the spike in the power rail. Some people used relays or digital ICs to add a time delay, which I figure might go against Morsel's "keep it simple" principle.

I wired my PPA heaphone output to a DPDT switch which works pretty well. However, it would be better if there are holes on the PCB to wire the switch directly to the board in stead half way between the output jack and the OL, OR, OG holes.
Reply
post #266 of 565
12/12/04 at 1:03am
Quote:
Originally Posted by koladd
I wired my PPA heaphone output to a DPDT switch which works pretty well. However, it would be better if there are holes on the PCB to wire the switch directly to the board in stead half way between the output jack and the OL, OR, OG holes.
I used switches too. I couldn't think of a better way/higher quality means of preventing a on/off pop... Relays use power (which for a battery powered system is a negative) and may cause a small technical degradation...


JF
Reply
post #267 of 565
12/12/04 at 3:07am
We didn't design any pop-elimination scheme into the PCB, but you could always do whatever you want when you build the amp. Relays, switches, whatever. I find, though, on the M³ prototype and listening through the HD600, there is virtually no turn-on pop, and only a faint hiss and click on turn-off. Nothing to be worried about as far as headphone safety is concerned.
Reply
post #268 of 565
12/12/04 at 4:43pm
Quote:
Originally Posted by amb
We didn't design any pop-elimination scheme into the PCB, but you could always do whatever you want when you build the amp. Relays, switches, whatever. I find, though, on the M³ prototype and listening through the HD600, there is virtually no turn-on pop, and only a faint hiss and click on turn-off. Nothing to be worried about as far as headphone safety is concerned.
That sounds nice. I think I've been paranoid with my HD600 hooked up to PPA. I've never tried once to see how loud is the pop with HD600. Maybe it's not as loud as with HD280 due to its higher impedance. I may try it later.

JF, I'm gonna try using a 4P3T rotary switch to realize the power on/off sequency. 2 poles for power and 2 poles for the headphone output. Since there are 3 switchable positions, I'm gonna implement it this way.

1st position: both power and headphone off
2nd position: power on and headphone off
3rd position: power on and headphone on

With toggle or rocker switches this could be only done with two switches. Sometimes you forget which to turn on/off first. The rotary switch will totally eliminate this problem.
Reply
post #269 of 565
12/12/04 at 5:11pm
mm interesting. i think i will try this idea out on my next headamp.
Reply
post #270 of 565
12/12/04 at 7:12pm
Quote:
Originally Posted by koladd
JF, I'm gonna try using a 4P3T rotary switch to realize the power on/off sequency. 2 poles for power and 2 poles for the headphone output. Since there are 3 switchable positions, I'm gonna implement it this way.

1st position: both power and headphone off
2nd position: power on and headphone off
3rd position: power on and headphone on

With toggle or rocker switches this could be only done with two switches. Sometimes you forget which to turn on/off first. The rotary switch will totally eliminate this problem.
Very interesting idea. You'll need to verify that between positions 2 and 3 that power doesn't turn off... Make before brake. (If it's not, then your idea probably will still work because the switching will be fast...the capacitor will probably hold the voltage up...)

I've gotten used to a power on sequence. The headphone out switches is over the power switches. So, to turn on it's: (from bottom to top) up, up. Then for off it's: (from top to bottom) down, down. This is a smooth operation... I use totally seperate power for each channel. So, there are seperate switches for left and right. They are next to each other so, I do this with one hand... (Not that headphone listening has a problem with channel seperation... : ).


JF
Reply
New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › M³ Project Announcement