[lextek]

Which jack were you plugged into? OTL or Transformer switch postion? You must have had it cranked.

Bob

 

[franktalk]

What was that? Cranked too loud? Say it again please!

Actually not. I'm talking about maybe three or four click stops up from the zero point.

I have to admit that I am beginning to be concerned. I' m wondering if there is something wrong with the amp since there have been times it has been magical but there have been as many other times that it was not listenable. It really seemed to be better before being "burnt in." The breakup point really seems to be more in the upper register of the bass frequencies now rather than on the deepest notes.

Any thoughts other than a tube roll which is in process?

 

[Kim Hardee]

I've had my MG Head OTL about a week, and even though the right channel is intermittent I have been able to make some observations and measurements.

I think the best sounding option is the transformer output with no feedback. I do not hear any hum and almost no hiss at full volume with stock tubes. The bass is very slightly rolled off, but not bad (I measured -3db at 25 Hz). The measured output impedance is about 12 ohms.

My second choice is the transformer output with feedback. The only advantage here is slightly more bass, and the almost inaudible hiss is gone. The bad news is the loss of imaging.

I know this goes against other's reviews, but I don't like the OTL output. The bass seems to be artifically boosted with my HD-600s. Also, bass notes sound smeared together on music with very fast bass lines. I guess if you want more (boosted) bass, then this output is a good option. I my opinion this output just doesn't sound as good as the transformer output (either with feedback or without). Keep in mind I am only talking about results with my HD-600s.

I think the reason for this is the very high output impedance of the OTL output (I measured about 7K ohms). This may explain the sloppy bass and the bass boost since the HD-600 headphones have almost a 2X increase in impedance at frequencies around 100 Hz. This would cause an increase in voltage to the phones at these frequences. I tried plugging in some Grado phones into the transformer output while listening to my Senns through the OTL output, but didn't hear any improvement. I was hoping that doing this would lower the output impedance of the OTL output enough to make a difference. The measured OTL output impedance dropped to 3.5K (still very high).

One thing that might help is to replace the 100uF electrolytic caps in the OTL output with 2uF film caps. My calculations show that this should not affect the frequency response due to the high output impedance. I previously thought that even 100uF wasn't enough, but I neglected to take the output impedance into account. This may improve the sound, but will probably not fix the bass problems.

I've mentioned this before, but another issue is the loud pop if you plug phones into the OTL output after the amp is powered up. This seems dangerous for the phones. I recommend adding 22K resistors from the OTL outputs to ground to bleed off the capacitor charge.

I would be interested in hearing other opinions.

 

[lextek]

Tried a Telefunken ECC83 today. Not much diiference from the stock Tesla. I aslo had a new set of Red Clou's so I'll have listen some more. The Telefunken doesn't glow as much as the Tesla.

Lextek

Happy New Years

 

[Nezer]

Quote:

Originally posted by franktalk I' m wondering if there is something wrong with the amp since there have been times it has been magical but there have been as many other times that it was not listenable.

Welcome to tubes. This is the issue I've had with tube guitar amps that has me concerned with headamps. I would start with your power. Ge up at 3am every day for about a week and see if it's consistantly magical when the power is cleaner than during the day. There could be a problem with the amp but I've seen perfectly good guitar amps do *exactly* the same thing. Sounds magical one day and the next it sounds like junk. No consistancy whatsoever. After researching this a bit I finally came to the concolusion that power was at play.

Of course, I ditched the whole tube guitar amp thing and now I use a digital modeling amp from Line 6. It sounds the same every time plus it has about 5 billion personalities.

 

[lextek]

If power is the problem I might try some sort of AC conditioner like PS Audio Ultimate Outlet. I'm on a Tube kick now. As long as it sounds good solid state or tube, I don't care.

Lextek

Happy New Year

 

[kelly]

Between here and HeadWise, you guys have convinced me that I really really want to buy an MG Head OTL.

I live in Dallas, Texas -- so where is the best place to order one? All of the references I've seen on here actually link to the MG Head DT, not the OTL. If there's somewhere I should email who has really good prices and service, just the email address is fine. Also, what was your total price including shipping? (I reallize mine will be slightly different due to location.)

The second part of this question--I'm a total newbie to tube amps and that's part of why I'm eager to experiment with this unit--it seems like the most affordable way to try it. But... which tubes am I absolutely going to want immediately, where's the best place to buy them and the prices? (Model numbers help a lot, remember, I'm new at this -- never bought a tube before.)

Thanks

Kelly

 

[Nick Dangerous]

Buy amp from Headroom (www.headphone.com).

Tubes from Uncle Ned (www.triodeelectronics.com).

Buy a 12AX7A Svetlana Russia Tube, 6BQ5/EL84 EI Yugoslavia Tube Matched Pair, and 6BQ5/EL84 Tesla/JJ (Slovakia) Matched Pair.

This is a good place to start. In fact, this is exactly what I just did.

 

[chych]

kelly, try calling headroom (www.headphone.com) via phone. Even though they are listed as "DT" models, they are OTL, or will be... for some at least... The phone would be a better solution...

The stock MG Head comes with some decent tubes, you should stick with those fora while and then upgrade when you really want to. www.upscaleaudio.com sells tubes, and there are a bunch of other sites.

 

[lextek]

Does anyone know of a source that would be able to replace the "detent" style volume control of the MG OTL with a "smooth" type? My only complaint.

thanks,
Lextek

 

[kelly]

The price on Headroom is listed as $370. Is that the going price for the OTL model?

Kelly

 

[mc whak]

If you'd have ordered before the new year it would have been $330, but they raised the price (not just Headroom, but Divertech as well).

 

[Dusty Chalk]

Quote:

Originally posted by Nezer This is the issue I've had with tube guitar amps that has me concerned with headamps. I would start with your power. Ge up at 3am every day for about a week and see...

A real musician would have still been up from the night before!

j/k...

 

[Nezer]

Quote:

Originally posted by DustyChalk A real musician would have still been up from the night before! j/k...

Been there, done that... The trick is to stay "medicated" the whole time. Fortunatly I'm much older now and my body nor mind can take that abuse any more.

 

[Dusty Chalk]

Quote:

Originally posted by Nezer Fortunatly I'm much older now and my body nor mind can take that abuse any more.

I think you meant unfortunately. I'm there with you my brother.