New Millett Hybrid Maxed Amp
Sep 12, 2008 at 7:37 PM Post #5,461 of 6,727
Quote:

Originally Posted by digger945 /img/forum/go_quote.gif
manaox,
I wanna know if your eyes water when you get the Opus feedin' the Max.

Yea that's the only reason I didn't go home (Asheville) this year, cuz I bought way too many diy stuffs and goodies
evil_smiley.gif
confused.gif
frown.gif
atsmile.gif



I wish I could do that! I do have a populated OPUS, but no ballsie. TPA is out of stock of them too. Have to wait for more funds anyway... so no biggie.

My max has really started settling in now. It generally takes about 5 hours for it to really settle though it seems with my voltage meter still, though my tubes have well over 50 hours. It sounds really great after its been on about two hours, but even I can notice some soft clipping before that.

The weirdest thing is that things don't sound like they are located properly in the right earphone. I listen to a lot of holophonic stuff (3D aural recording for headphones) and the right side is kind of collapsed. Things that should sound directly behind me sound off to the left corner of the back end and not the middle, regardless of the three sources (granted that they were pretty low end) I've tried. The right side sounds moved to the back end as well. Now something may be wrong with my HD650s which I will test with some different phones later (not the UE11, don't worry about that), but does anyone else have any ideas on something that could cause this with the amp build?

Its like the front right quarter area of headspace is being almost completely bypassed which I thought might be fixed by burn-in. With binaural or holophonically recorded tracks, it feels like I have had my right ear relocated closer to the back of my head.
eek.gif
Its a very interesting yet fatiguing effect that has me constantly wanting to twist my head around to focus on the source of the sound on the right (and with headphones attached to my head, of course that doesn't work).

I replaced some of the transisters in the left channal when I repaired my mistakes, but things actually sound in their proper places there. So unless its one of those things where the brain interprets audio cues on the left side and they aren't projected properly to connect with the right side noises, I am not sure why the never touched matched transistors would be causing this. At least I can say this is interesting and could be a variety of thing such as source, cable, amp, headphones, hearing, or just brain damage. :p I rule out the source and cable just because of them working with other things perfectly fine and my brain or hearing isn't affected without the headphones. That leaves either the headphones or amp. If its actually my amp and I obviously suspect it is, it is a very odd occurence to me.
 
Sep 12, 2008 at 8:24 PM Post #5,462 of 6,727
Try swapping the tubes and see if the issue follows the tubes.

What you describe is somewhat typical for a tube that's either not quite up to the snuff of the other one, or one where the bias has fallen off. Bias on the tubes will continue to drop for 2-3 hours on a typical 12AE6, but more than likely, they will not drop the same. The result is that after a couple of hours your soundfield will seem a bit mis-matched.

Sometimes this effect can occur with a difference in the tenths of a volt. In those cases, you're often better off just listening to your headphones while you make a fine bias adjustment. If that doesn't fix it, then it's a bothersome mis-match in the tubes.

They take some fiddling ... welcome to tubes.
smily_headphones1.gif
 
Sep 12, 2008 at 8:33 PM Post #5,463 of 6,727
Quote:

Originally Posted by RubberDuk /img/forum/go_quote.gif
Just dropping by to mention I bought a MAX built by a fellow head-fier and I'm in love. That is all. Carry on.
tongue_smile.gif



Hey RubberDuk, I am so happy to hear that. Enjoy.......
biggrin.gif


James
 
Sep 12, 2008 at 10:04 PM Post #5,464 of 6,727
Hi

how do I measure the heater voltage to the tube?

Thanks
Frank
 
Sep 12, 2008 at 11:07 PM Post #5,465 of 6,727
Quote:

Originally Posted by fc911c /img/forum/go_quote.gif
Hi

how do I measure the heater voltage to the tube?

Thanks
Frank



Right lead of R1 to V+ is the heater voltage for the Right tube.

Left lead of R1 to Gnd is the heater voltage for the Left tube.

Alternatively, you can measure the voltage drop across R1, subtract from the value of V+, and divide by two.
smily_headphones1.gif
 
Sep 12, 2008 at 11:16 PM Post #5,466 of 6,727
Quote:

Originally Posted by tomb /img/forum/go_quote.gif
Right lead of R1 to V+ is the heater voltage for the Right tube.

Left lead of R1 to Gnd is the heater voltage for the Left tube.

Alternatively, you can measure the voltage drop across R1, subtract from the value of V+, and divide by two.
smily_headphones1.gif



ok thanks Tom

I have 12.7 on both sides on one of my Millet amps and 12.6 and 12.9 on the other board. How come the differance in voltage on the second one?

BTW I am running 29v

thanks
Frank
 
Sep 13, 2008 at 3:02 AM Post #5,467 of 6,727
Quote:

Originally Posted by fc911c /img/forum/go_quote.gif
ok thanks Tom

I have 12.7 on both sides on one of my Millet amps and 12.6 and 12.9 on the other board. How come the differance in voltage on the second one?

BTW I am running 29v

thanks
Frank



Just guessing, of course, but I'd chalk the difference up to the variance in the tubes. The heaters will draw what they need to draw, but there may be slight variances (although I can't remember seeing a difference that big). Swap them with each other and see if the voltage difference follows. If not, then you may have a mis-matched part somewhere else on the board.
 
Sep 13, 2008 at 1:10 PM Post #5,468 of 6,727
Quote:

Originally Posted by tomb /img/forum/go_quote.gif
Just guessing, of course, but I'd chalk the difference up to the variance in the tubes. The heaters will draw what they need to draw, but there may be slight variances (although I can't remember seeing a difference that big). Swap them with each other and see if the voltage difference follows. If not, then you may have a mis-matched part somewhere else on the board.


Hi Tom

you guessed right it moved with the tube. At least I know it wasn't something I did.
biggrin.gif
Maybe it will settle down after the tube burns in for a while.

Frank
 
Sep 14, 2008 at 3:03 AM Post #5,469 of 6,727
frown.gif
another soundless Millet...

some things to note:

Sound does come out of RB14L/R

Everything has been biased: @85mV on BD137/8, 27VDC across board, 13.5VDC per tube bias

QM1 is in the correct orientation (wording facing the front of case)

Tubes light up and get warm

I do not hear any audible clicking from the relay.

transistor heatsinks get a tad warm, but not uncomfortablly hot like stated on the website


Any tips/things i can try? I have a camera that can take decent macros if that will help.

Thanks in advanced!
 
Sep 14, 2008 at 3:48 AM Post #5,470 of 6,727
Quote:

Originally Posted by acold7dusta /img/forum/go_quote.gif
frown.gif
another soundless Millet...

....

Sound does come out of RB14L/R
.....



[size=xx-small]
Check the Relay. does it click after a few seconds?..[/size] it could be the E-12 delay circuit. check out all the parts there for values, orientation, shorts, cold solder joints, etc. pics would be good if you don't find anything and of that region specifically.
 
Sep 14, 2008 at 9:23 AM Post #5,471 of 6,727
Quote:

Originally Posted by ruZZ.il /img/forum/go_quote.gif
[size=xx-small]
Check the Relay. does it click after a few seconds?..[/size] it could be the E-12 delay circuit. check out all the parts there for values, orientation, shorts, cold solder joints, etc. pics would be good if you don't find anything and of that region specifically.



Yes - Russ is correct - it has to be in the relay circuit: sound from RB14L/R proves it.

Get us some pics as soon as you can. In the meantime, since you seem certain the BD139 is oriented correctly, check these:

- DM1, zener diode, backwards
- Not using a Darlington transistor for QM2 (MPSA14)
 
Sep 14, 2008 at 4:31 PM Post #5,473 of 6,727
I just noticed that I am using a MPSA14 transistor for QM2... but thats what the bill of materials calls for
confused.gif
 
Sep 14, 2008 at 4:50 PM Post #5,474 of 6,727
Sep 14, 2008 at 5:10 PM Post #5,475 of 6,727
Just to make sure - have you left the amp on for more than a minute or two? It may take up to 90 seconds or longer before a relay will trip. That can seem so long it may appear as if it's not going to work.

Your parts look OK, except as you mention, we can't see DM1 in those shots.

MrMajestic2's suggestion is a good one. It looks like you may not have complete connection on some of those joints.
 

Users who are viewing this thread

Back
Top