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I think my mg head is taking a dump!

post #1 of 34
Thread Starter 
today of all days, I just got my AT W1000's and was trying to listen to them when I noticed a high pitch whine in the right ear cup of the headphones. So I started investigating, checking tubes, connections, interference etc. Finding nothing I decide to completely turn off the source and just sit there with the headphones on and listen, sure enough there it is, an intermittent high pitched squeal now in both cups. Has anyone experienced this with this amp? Anyone have any idea of the problem, and what should I do, I bought the amp from headroom and they no longer sell them anymore, this thing is only about six months old, it's gotta be under some kind of warranty right??? Help!!!!!
post #2 of 34
Have you tried the Head in a different room, different outlet?
post #3 of 34
Tubes, tubes, tubes...
Turn the amp off. and then reseat all the tubes, reseat the cables, reseat the headphone cable. Then check your switches and sources.

Then, if that doesn't help, turn it off again and after a little while, swap the left and right channel tubes.

If that doesn't solve it... then turn it off, wait awhile, unplug the unit and then remove the bottom panel. Once done, reroute the two wires which come from the power input by twisting them while taking them around the panel section.

If you get to this final solution, which usually only affects one channel and not both, come back here and ask before trying the fix....
post #4 of 34
Thread Starter 
thanks guys, I already reseated the tubes and the headphone plug and the power cord and the interconnects. as for taking apart the amp itself I'm not sure I want to start doing that sort of thing because I'm not skilled in electronics, and wouldn't that void any sort of warranty?
post #5 of 34
First, if it seems like you started having problems when you changed to a different headphone set. Have you tried using a different headphone set to see if the problem is due to the amp and not the headphone?

Next, tubes are like voodoo. Try swapping the tubes (el84s) to see if that helps.

Finally, if the whine persists, then unplug it, take out the tubes, and open that sucker up. Joe L knows about the twisty wire fix and I haven't heard anyone voiding whatever warrenty exist by doing so....

I have a new MG Head due to arrive tomorrow, and you better believe that I'll probably be doing the twisty on this unit as well...
post #6 of 34
Thread Starter 
I tried with both the AT's and my senn hd600 and it happens with both of them. I am really leary about taking it apart but when time allows I guess I'll give it a try. I think I'll call headroom tomorrow and ask their opinion as well. I'd rather send it in for service and have it done right rather than screw it up worse than it is right now. thanks for the advice merc and joe!!
post #7 of 34
Do you have another driver tube? The 12AX7? That has right and left sides so it can be a common point of failure. The EL84’s are left and right only. It wouldn’t seem likely that both would fail unless it’s something inside the amp.

You say you’ve rolled the tubes so try swapping the 12AX7.
post #8 of 34
Quote:
You say you’ve rolled the tubes so try swapping the 12AX7.
And, BTW... a nice substitute for the stock 12AX7 is a 5751... ?

Wouldn't it be cool if your whine led you to a better sounding replacement for your 12AX7...?

If you can get your head whineless, I will send you a better tube for your head.

Hmmm, maybe it is time for Nick's Tube Roll 2003?
post #9 of 34
ooo I want tubes for my MG-Head! Hopefully it'll be here next week - so many great 5751's to try (after some searches it seems there are several top-quality 5751's or 12AX7's that no one's tried yet! but I guess it doesn't make too much sense to spend half as much as the amp on a single tube...) - too bad I have no money to try them Any advice on where to get some cheap & great tubes would be appreciated


-dd3mon
post #10 of 34
Since the problem started in one ear, and then went to the other as well, that could mean either of the tubes is suspect. It could be the 12ax7 went out one half at a time, or that on EL84 went out, and then it's mate went out next. So, try swapping out the tubes in stages and see if the problem goes away, or stays. You didn't mention tuberolling as an attempt to solve your problem, so this would be a great place to start. If that doesn't fix the problem, you'll have to talk to HeadRoom about having someone help you troubleshoot it down to something else internally.

Sorry to hear your amp is going south on you fyrfytrhoges. It's always a bummer when someone's amp goes out.
post #11 of 34
Quote:
but I guess it doesn't make too much sense to spend half as much as the amp on a single tube.
Holy Cow...? Is that how much things have changed in the past months? Last I checked(last week), a very best rated Sylvania JHS went for around $20 and many not so lesser 5751 tubes went for under $15 and $10, NOS. Of course, the highly rated EL84s, such as the JJs, go for around $10 or so...?

Add it up and it isn't even close to the price of even an MG Head OTL Mk I much less a Mk II.

Hope that info helps!
post #12 of 34
Thread Starter 
thanks guys, I don't think this is a tube problem, the tubes I am using are fairly new ones, I'm going to call headroom in the morning and see what they can do for me, I guess maybe I'll send it to them or if they won't take it I'll send it somewhere else and have it tested, in the meantime I managed to strip one of the screws that holds the bottom panel on the amp, live and learn I guess is the phrase of the day for me. by the way I swapped the middle tube - raytheon and mullard and had the same problem with both. guess it's back to the headroom little for a while, probably a long while the way it looks!
post #13 of 34
Well first off the prices that I've found (from dealers and even eBay lately) for the tubes you mentioned are much higher, $40 or more! But I was referring to tubes not yet attempted by Head-Fi'ers to my knowledge, check AudioAsylum - several very rare and high dollar 12AX7 compatible tubes discussed there.

-dd3mon
post #14 of 34
fyrfytrhoges:

Don't give up. I am determined to solve your problem!

And..., you will thank me for doing so later by posting your listening joy from the Head...?

You mentioned that you turned off your souce for the whine test. Did you also unplug it so that the Head had NOthing plugged into it?

DID anything else. whatsoever, change in the system from which the source is connected? Did you try using ONLY the source CD player and the amp plus the Senns?

As I think of more ideas, I'll send them to you...!
post #15 of 34
dd3mon:
Quote:
Well first off the prices that I've found (from dealers and even eBay lately) for the tubes you mentioned are much higher, $40 or more!
Oops... here is $12.50 each http://cgi.ebay.com/ws/eBayISAPI.dll...category=14947

And, here is another buy you might have missed? http://cgi.ebay.com/ws/eBayISAPI.dll...&category=3284

Anyway....... If you shop carefully, you can find the 5751 you want for much less than you think... IMO.
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