[joelongwood]

I'm using the Ei84s. I do have a question though. After a few hours, I decided to try various 'phones with my Head. When I plugged in the CD3000s I was greeted with a noticeable "buzzing" in the left channel. Music masks it most of the time, but in quiet passages I can still hear it. I then listened carefully to the Senns again and noticed the "buzz' is there very, very slightly. But I could swear it wasn't there in the beginning of my listening session, because I was listening specifically for any extraneous noises. It's a little more noticeable on the MS Pros, and totally non-existent on the Grado HP-1s. I switched the tubes, right to left, and the 'buzz' is still there. I've also noticed, that with no signal, the "buzz" remains constant until about the 2 o'clock volume setting and then DECREASES to almost nothing. Right before full volume, however, it picks up again in intensity. Any clues?

 

[chych]

Probably some grounding errors... Try changing power outlets? Wing posted a few tips on this somewhere in this thread.

The loudness probably has to do with the sensitivity of the headphone. Strange though, my CD3000s do not show the microphonics with my 12ax7 but my etys do. No buzzing though, though my volume is at 2 clicks (!!... ~8 o'clock) now, there is waaaay too much gain on this amp for me, especially from a 7V source.

 

[timoteus]

Finally got around to trying the "Wing Mod" as it should now officially be called.

I really like the sound now as everyone else who has tried it so far. I can echo the comments of wing, chych, and joelongwood. My Head DT was a quiet and well behaved unit with no quality control problems to start with and so I haven't experienced any problems with hiss, hum, or microphony since the mod.

Since I have a number of different decent tubes I have been rolling them since doing the mod. They all sound better than before. Even the stock JJ ECC 83 which I hadn't plugged in for quite awhile seems to sound better than NOS did before the mod. A great tube especially considering the price.

I will sling a few adjectives at you in an attempt to describe the sound. Richer, fuller, less strained, bigger, more detail, less smear, more in your face which helps with the HD600's laid back style.

This is a keeper mod in my opinion. Thanks go to wing for sharing. Maybe wing will come up with a transformer mod or change in the future??? Way to go wing!!

Output tubes:
* EI EL-84
the sometimes stock 6P14

Driver tubes:
JJ ECC 83
Telefunken 12AX7/ECC83 greyplate
*RCA 5751 COMMAND

* favorites so far

 

[joelongwood]

Regarding my discovery of the left channel buzz yesterday, the mystery continues. I listened to the CD3000s off and on all day. Guess what? NO buzz at all.......silence. Then around 5 pm the buzz appeared.......but it was slightly different at first. It would go from a soft buzz to a louder buzz in a second or so.......almost like it was cycling. That lasted about 15 minutes, and now it's back to a steady buzz. Could be one of the many electrical devices in this house......computers, stereos, oil burner motor,......anything. At least I know it's not the MG Head itself.

 

[Wing]

Congrats joe and timoteus, you have discovered Single Ended Triodes with no global NFB. A word of warning though, the black electrical tape I used didn't stick too well. Make sure that those ends are really well insulated.

The buzz, I believe is electrostatic interference/noise/ ground loops in the AC. This would explain its intermittent nature. I have received my toroids (Avel Lindberg, Plitron) and will report on their performance once I get around to putting them in. I may also try to re-orient and isolate the stock transformer on my baseline MG Head once the toroids are in the experimental amp. If that works, then there may not be a need for toroids.

 

[Hardhead]

Originally posted by timoteus
Finally got around to trying the "Wing Mod" as it should now officially be called.

While Wing may have discovered this mod independently, a review of Joe Lau's posts on Head-Fi will clearly demonstrate that the manufacturer of the Head is more than willing to make suggestions to improve the sound of his creations.

 

[timoteus]

Congrats joe and timoteus, you have discovered Single Ended Triodes with no global NFB. A word of warning though, the black electrical tape I used didn't stick too well. Make sure that those ends are really well insulated.

Thanks Wing, I put a very small wire nut on the end of each wire and then tucked them away.

 

[Wing]

I would like to clarify that I did not discover the mod independently. Joseph Lau I believe had posted an article on how to mod the MG Head to OTL. Part of that mod was to remove the NFB. Nobody, as far as I know, nobody had posted anything on the boards regarding the results of trying out the mod. I may just have been the first to do so.

 

[wasifazim]

A couple of snips (no, not there) and my Head DT completes its transformation as well. The gain is nuts, I've really got to turn the volume down. I'm experiencing the same left channel volume-independent buzzing others have reported, but oddly enough it goes away completely with the impedance switch set to low.

 

[joelongwood]

Quote:

I'm experiencing the same left channel volume-independent buzzing others have reported, but oddly enough it goes away completely with the impedance switch set to low.

I find the the buzz to be headphone dependent....using higher impedance/less sensitive 'phones (AKGK501,K340) the buzz is simply not audible. With Senn HD-600s, the buzz is ever so slight, and does disappear with the impedance switch set to low. But that seems to kind of collapse the soundstage and the music does not sound as full and rich to me. The buzzing is worst with the Sony CD3000s and CD1700s......which is not good, because these things sound GREAT with this mod. But, as I posted earlier, this damned buzzing (which BTW is VERY annoying and detracts from the music, simply because I know it's there), seems to be time-of-day dependent in my house. All morning and afternoon.....silence. Around 4 or 5 in the evening, the buzzing returns. Very strange.

 

[wasifazim]

joelongwood, have you (or anyone else for that matter) been able to determine if the buzz is reduced or eliminated by using a good power conditioner? I'd like to solicit opinions before getting an Ultimate Outlet or something..

 

[joelongwood]

I know absolutely nothing about power conditioners.

 

[Kim Hardee]

Are any of you that are experiencing buzzing or humming using the tube cage? I wonder if the cage would help shield the tubes and reduce or eliminate the noise.

 

[joelongwood]

No tube cage here. I have a Dynaco ST70 tubed amp that exhibits more hum without the cage, but this noise is not a low pitched hum. It is definitely a BZZZZZZZZZZZZZZ sound. High impedance phones do not reveal this buzz at all......dead silence.

 

[wasifazim]

Just lovely, I've solved the buzzing problem..turn off the dimmer-controlled lights in the room and it all goes away. Methinks that dimmer needs to be removed this weekend..