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Please help me troubleshoot Millett Max issue (no output)

post #1 of 18
2/17/10 at 8:01pm
Thread Starter 
I recently purchased a millett max from a member on here, however, when I connect it, I do not hear ANY sound at all through the headphones.

I have a voltmeter and checked the RCA out of my DAC and I see that there is current, plus, my dac has a headphone out and that works fine...so Im pretty sure its not that.

Is there anyway to test the amp to see where the problem lies? When I plug in the headphones and power the amp on, I do not hear anything. When I raise to volume to max I do not hear any noise at all through the amp.

The tubes do light up though, so the amp is definitely powered on.

TIA for any help!
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post #2 of 18
2/17/10 at 8:07pm
Maybe its a bit silly question, but just to make sure. Have you tested the amp some 2 or 4 minutes after turning it on? The Millett Max has an internal switch (a relay, really) that remains disconnected for the first 2 or 4 minutes after turning on the amp, for protection of the headphones. You'll actually hear a slight click when it connects.

cheers!
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post #3 of 18
2/17/10 at 8:58pm
Thread Starter 
Well...that was a good catch, as I DIDN'T do that.

However, I started it up with the headphones plugged in, waited 10 minutes and then tried it and still no luck.

I tried it twice. The first time, I disconnected the RCA's and reconnected them while the amp was still on and powered off on me.
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post #4 of 18
2/17/10 at 9:16pm
Quote:
Originally Posted by pacmantravis View Post
Well...that was a good catch, as I DIDN'T do that.

However, I started it up with the headphones plugged in, waited 10 minutes and then tried it and still no luck.

I tried it twice. The first time, I disconnected the RCA's and reconnected them while the amp was still on and powered off on me.
We'll need some pics. If you supply some pics of the outside, we can tell you how to take it apart - they're all different, to some degree. Once that's done, you can take some pics of the inside and let us see if we see something.

In the meantime, perhaps you should contact the person you bought it from. If he sold it to you, he should support it so that you can get it working, at the very least. It may be something simple like one of the power leads came loose in shipping, etc.
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post #5 of 18
2/17/10 at 9:28pm
Thread Starter 
Here is a pic of the amp from the seller.

Im assuming I need to unscrew the front and back?

Also, just want to make sure...when I insert the tubes, are they supposed to click or anything? When I put them in, I couldn't really tell if they were in snug or not, however, they are lit up right now.

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post #6 of 18
2/17/10 at 9:29pm
Uhm... remember to bias tubes?
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post #7 of 18
2/17/10 at 9:47pm
Thread Starter 
...I have no idea how to do that and google didnt really help too much.

Can you point me in the right direction?
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post #8 of 18
2/17/10 at 10:03pm
MAX Setup and Bias Settings

Millett Hybrid amps need to have the tubes biased whenever installing new tubes (and that includes plugging same ones in unless the tubes are identical or you remember which is left vs right ).
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post #9 of 18
2/17/10 at 10:10pm
Thread Starter 
Ok...I'm going to have to check that out then.

In the meantime...what does it mean when sound only comes out of one ear (the right one)?

That's where Im at right now...just have sound coming out of one ear.
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post #10 of 18
2/17/10 at 10:32pm
Thread Starter 
Ok...well, I switch the tubes around, made sure they were plugged in firmly and now I can hear from both ears.

Should I wait for the tubes to be burnt in before setting the bias?
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post #11 of 18
2/17/10 at 10:53pm
No, bias them now.
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post #12 of 18
2/17/10 at 11:02pm
Don't feel bad. With the Millett MiniMax I used to own, I actually ordered a second set of 12AE6 tubes from Craig at Whiplash because I thought the initial ones he sent were bad. Turns out I didn't have my DMM set properly. If it had it would have told me that the bias for the 12AE6 tubes (going from the stock 12FM6) was 24vdc and should be around 13.5vdc. <<Facepalm>>
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post #13 of 18
2/17/10 at 11:31pm
Actually, if the PSU is set at 24V, tube bias should be 12V. Always 1/2 of PSU voltage. The 13.5V example is because most people run their amps at 27VDC.
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post #14 of 18
2/17/10 at 11:35pm
The PSU on the Whiplash Millet MiniMax IS set to 27V. I typically ran tubes around 15V as to me they sounded better.
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post #15 of 18
2/17/10 at 11:48pm
OK - I'm shocked. Never would I have considered that two tubes would've both been so far off in bias that he got no sound in both ears. A little sound in one, yes - but both to be completely silent? Either the OP didn't describe his first post accurately, or something else was going on, IMHO.

At any rate, it certainly sounds like a bias issue from the later posts.

To the OP - most likely the original owner had the amp biased. So, the only thing you need to do is find out which tube should go in which hole. Sounds like from your last post you found it.

EDIT: Yes, some tubes with some headphone combinations may sound better biased at 15V or more - but you'll give up voltage swing which is a disadvantage with high impedance phones. To get the maximum swing and power FA is correct - bias at 1/2 the supply voltage. That's the standard recommendation unless you're a tinkerer.
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Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Please help me troubleshoot Millett Max issue (no output)