[Dusty Chalk]

http://www.metasonix.com/TM4.htm

and they're sold here:

http://www.vacuumtube.com/newpage1.htm

I saw this mentioned in Recording magazine. The picture of it showed a pen that wasn't much shorter than the box longways. US$450

 

[domer2004]

Looks great, but how does it sound? 1w @ 8ohms with 5 (read FIVE?!?!?!?)% THD?

Brett

 

[Dusty Chalk]

Quote:

Originally posted by domer2004 Looks great, but how does it sound?

I have no idea, personally. The product has only just been announced, it's not even on that second page I linked to, I only know they're going to sell it because I know they sell Metasonix stuff.

 

[bootman]

Quote:

Looks great, but how does it sound? 1w @ 8ohms with 5 (read FIVE?!?!?!?)% THD?

To be honest, that is not a surprising spec for tube gear!

 

[domer2004]

I guess I just gave away my inexperience with tubes!

Brett

 

[dngl]

tube harmonic distortion doesn't sound nearly as nasty as solid state harmonic distortion. It's all about evens vs. odds.

Only goes down to 70hz? That's an outrage!

 

[Dusty Chalk]

Quote:

Originally posted by Jon Beilin Only goes down to 70hz? That's an outrage!

Yeah, that can't be right. If it is, I'm not getting them.

OTOH, if you want that headphones/sub system, you wouldn't need a crossover!

 

[Morse]

Well, not all valve amps have rotten numbers and large amounts of even harmonic distortion; it depends on whether it's a Single Ended or Push Pull amp, and on how much Negative FeedBack is applied in the gain stages of the amp. Usually low cost valve amps don't have more than a driver stage and an output stage, so they won't have many NFB loops. Also, Push Pull amps cancel out even harmonics with valves, just like they do with transistors, leaving primarily odd harmonic distortion.

Looking at the complement of valves, the unit in question is a Single Ended design, rather than a Push Pull, which definitely accounts for the numbers. If you're unfamiliar with SE amps, take a look at http://www.hometheaterhifi.com/maste..._toc_main.html
(you'll have to click on "Product Review - Bottlehead Paramour Monoblock Single-Ended Class A Triode Tube Amplifiers - April, 2001"

That 5% number is at clipping (the THD is usually less than that), and the amp looks like it's got a passive preamp, which usually results in somewhat lacklustre bass, but a wonderfully clean and transparent sound overall.

My only problems with what I saw in the ad were 1. I haven't found the 6BM8 valves that it uses yet, 2. I don't have the schematics for the amp or the specs on the valve yet, so I can't determine how stable the little guy is with ugly loads and 3. I can't afford one for a couple of months!!

Thanks for letting me know about this neat little amp!
Hopefully I didn't put anyone to sleep with this post!

Enjoy your music,
Morse

 

[Morse]

Eureka!

Scratch what I said about not being able to find anything on the 6BM8 valve; Svetlana still makes them, and I've found a couple of places that stock them.

For anyone who's interested, it's a triode/pentode dual valve; the pentode section has an AF (At Failure) rating of 1.8 watts. There's also a very useful little technical bulletin at Svetlana's website on this one.

Enjoy your music,
Morse

 

[domer2004]

grreeeeaaaaaaaatttt.....does that mean that it should sound good

Can someone please explain the difference between even and odd harmonic distortion? Damn it, can someone just guide to a place that will explain tube amps to me?

Brett

 

[Beagle]

Quote:

Only goes down to 70hz? That's an outrage!

That's weird, the X-Cans peters out around there too. What's up with that?

 

[Dusty Chalk]

Quote:

Originally posted by Beagle That's weird, the X-Cans peters out around there too. What's up with that?

Only if, by "around there", you mean 30Hz.

http://www.musical-fidelity.co.uk/pr...nts/index.html

 

[dngl]

For $450 you could get a Melos SHA-1... tube goodness to the max (at least in the under $1k category).

Anyway, odd order harmonics sound sorta grainy and nasty. Even order harmonics sound harmonious and rich. Get the three Stereophile test CDs and between the CD and the booklet you'll be an audio masta.

 

[domer2004]

hehe, thanx jon. Where can I find a Melos SHA-1? If it is really the isht, I will fork over the flow. Do tubes not go as low as SS though? That would be very disappointing to find out

Brett

 

[dngl]

The Melos SHA-1 is a hybrid amp. Signal stage is tubed, output stage is solid. It has the advantages of both and the disadvantages of neither. It's a truly wonderful amp, and stereophile puts it up with the MAX. unfortunately, it's discontinued. Search audiogon and ebay- they're not too hard to find. The Melos has a full frequency response. You're not losing anything.