What makes a speaker "tube friendly "?

[Colin]

Why is it that at preacherman DaddyDees Klipsch gathering in Little Rock, Arkansas (May, 2004) we listened to Diana Krall on the Wright 2A3, Led Zepplin on Deans monster Quad P/P, using classic Klipsch corner Khorns and there were no solid-state amplifiers anywhere?

[Colin]

What makes a loudspeaker tube friendly?

1. When you save so much money lugging the darn things out of some ole ladys house that you can afford esoteric, new or refurbished hand-made tube amplifiers!

2. When the loudspeaker is so well dampened with bags of sand that a tube amplifier can rest on top of them.

3. When the side panel of the loudspeaker has a fan that you can point towards your tube amplifier.

4. When your significant other yells shut that damn thing off so often that your expensive, hand-woven by Tibetan monks, gold filament tubes last for years.

5. When your son can run the pair flat out during the entire day that you are away without damaging either amplifier or speaker.

6. When it is a skinny B&O and slides into a narrow UPS shipping tube.

7. When the loudspeakers bottom is so low, that only SVS tubes will match to create a flat frequency response.

8. When the good looks of the cheap loudspeaker dont overshadow the dull looks of the expensive tube amplifier.

9. When it is constructed with horn drivers.

10. When it is bigger than a 2-drawer filing cabinet.

11. When it takes two men to move the sucker.

12. When the first watt matters.

[Deang]

Oh yeah, well answer me this: How many potato chips does it take to fill the Eifel Tower with Peanut butter?!

[sunnysal]

I think the la grange multiplier is needed to calculate the number of chips needed for the eiffel tower, i could be wrong though...

[jt1stcav]

Well, regardless of the chip/Eiffel Tower factor, and all the above mentioned "technical jargon", I for one, don't really care about the technical aspects of how or why a loudspeaker works with any given amplifier. I'm not knocking those who do, and I'm obviously thankful that there are electrical/acoustical engineers that also care (or we wouldn't be enjoying our systems). Their hard work is appreciated, but all I care about is the sound of my system; to my ears, my Cornwalls (with all their flaws) sound totally incredible via vacuum tube amplification, period! Maybe they'll not perform up to specs when I finally connect my 300B SET amp to them, but if the tone is pure and sweet to my ears, with all the smoothness (and coloration) that SET amps are known to possess, then I'll be totally pleased!

Thanks Dean, for the 15 ohm resistor tweek (for lack of a better word)...I appreciate your concern with the sound of my horns with the BEZ amp (if I ever get to receive it, I may just try it...it all depends how happy I'll be with this SET magic)!

[Deang]

I'm really happy with the sound of my "flawed" system too.

Things were getting too quiet around -- I thought it was time to stir things up a little. I guess I just wanted to make sure I hadn't lost the gift.

[Erik Mandaville]

Jt: I think you're going to like your new 300B amps very much!

[maxg]

Mark,

Notice I started picking holes in this thing before you did. Makes me quite proud - of course it wasnt in the right areas - but to the uninitiated, in a dark room, with their eyes closed, a questionable educational history and someone talking constantly in the background I reckon I could almost pass for someone who understands some of this.

On the other hand - maybe not.

[Deang]

"So Dean, what do you think about the guy's article now?"

I think I'm tired of thinking.

I think that if he's wrong, then I still have to figure out why the general consensus seems to agree with the premise, especially in regard to SET amps. I find it especially disconcerting that even those that manufacture SET amps, recommend speakers with benign impedance curves with their use.

I'm starting to think that Kelly was right all along, that there is no way to predict how something is going to respond or sound like in a system unless you just plop it in and have a listen.

[maxg]

"I'm starting to think that Kelly was right all along, that there is no way to predict how something is going to respond or sound like in a system unless you just plop it in and have a listen. "

Well that works for me

I have been surprised by how things performed against expectations (both better and worse) that now, when I audition something I am surprised when I am not surprised!

[Deang]

"...I am wondering what specifically the SET amp guys mean by "benign impedance..."

Pretty much what we've been talking about, and stated in the article:

"Tubes like a resistive load - it's really that simple. A resistive load translates to a flat impedance, and an inductive rather than a capacitive phase angle. A less technical way of looking at an ideal speaker from a tube's point of view is as follows: tubes like consistency. They prefer a speaker that doesn't swing from 8 ohms to 2 ohms and back again. If the impedance is going to dip it should do so gradually, or in small dips. Tubes like a steady load ..." -- This of course from the paragraph that set your teeth on edge.

"Another important parameter is speaker impedance. A speaker with a very flat impedance is very beneficial. "What constitutes a flat impedance?" you ask. Speakers are typically rated at 4 or 8 ohms but these values are rarely constant and due to the reactive elements within the actual driver and crossover components this value will vary with frequency. So for example a certain speaker might be rated at 8 ohms nominal and 6 ohms minimum. Check the specifications for your speaker or call the manufacturer for more details. For SE amps you want to avoid speakers that possess impedance dips down in the low frequency range. i.e. an 8 ohm speaker that dips to 4 ohms at 50Hz or a 4 ohm speaker that dips to 1 ohms at 60Hz because these dips have a tendency to suck the life out of your amp resulting in a soft bass response and loss of dynamics at these specific frequencies. So a speaker with a really flat impedance helps and generally one that fluctuates 2 ohms or less will be a good choice." -- Ron Welborne

http://www.welbornelabs.com/recomendspeaks.htm

"And with a very stable impedance (minimum 6.80), the Kosala is a very easy load for any amplification."

From the Data Sheet for the Adire Audio Kosala Loudspeaker:

http://www.adireaudio.com/Files/cut%20sheets/not%20for%20resale/Kosala%20Sales%20Brochure.pdf

"With no feedback dialed in, the output impedance is slightly less than 2 ohms, according to Dennis. That's certainly high enough to bother some measurement wonks (footnote 2). And true, you will likely get frequency-response anomalies if your speakers' impedance is all over the place. One rule of thumb with high-output-impedance single-ended designs is to pick a speaker whose impedance curve is relatively flatin other words, a speaker whose impedance stays close to the nominal 4 or 8 ohms across the frequency spectrum. If the impedance varies by more than 20% or so, up or down, you may have problems. Thus, with a nominal 4 ohm speaker, you wouldn't want the impedance to dip below 3 ohms or rise above 5 ohms. With a nominal 8 ohm speaker, you wouldn't want the impedance to stray beyond 6 to 10 ohms." -- Dennis Had

http://www.stereophile.com/amplificationreviews/740/index8.html

There's more of this kind of thing, I just don't have time to dig it all out.

As far as speakers with low sensitivity typically being the only type that have benign curves, I don't think that's really true. The ALKs do it for the K-horns, Belles, and LaScalas, there is the Adire Kosala referenced above, and some single driver designs. I don't know anything about other big horns like Altec/JBL, so I can't comment on those.

[artto]

Dean, since you have one of the most squirrelly Klipschorn setups I've ever encountered (although I too had mine in a 10x14 bedroom at one time, but thats another story), and you seem to have a perpensity for tube amps, I would like to extend you a personal invitation for a visit to my place before you exchange your Khorns for another equipment of the month selection. Ohio, right? Going to make the Indy trip? Take an extra day or 2 & hop on up. The Chicago Blues Fest is the same weekend (Thur-Sun).

[Deang]

The only thing I'm "changing" right now is my QUAD preamp for The Peach -- and I had made that decision months ago after spending a few days with the Blueberry prototype. On my list of things that make the most significant impact -- amps actually come last -- at least at this level. Speaking of which -- how long Mark? It is time to list my preamp for sale?

I'll be trying out a pair of Craig's monoblocks in the near future, and if there is anything out there that can move ahead of the QUADs in the areas that I think are most important -- it would be them. Craig's hotrodded Dynaclones are right up my alley, and I'm itching to hear them. I think AC balance adjustment, individual bias pots for each tube, and loads of filtering is what I think it will take to top what I have now. Not to mention the ability properly adjust for using 6550s, KT-88s, KT-90s, KT-66s, and EL-34s -- well, that kind of makes them a valve rollers dream.

Right now I'm happy, I'm not really looking for the Holy Grail or anything. I just want to try SET to see if I should add it to my list of future purchases. If it doesn't do what I think it will do -- I can just save myself some money down the road.

I like my set up -- it kicks arse.

I sure appreciate the invite, but I can't afford to be away from work right now, I have a lot going on, and it's all hot. Later in the summer I can probably get away if you're still into it.

[D-MAN]

Hoggy, I'm in Lynnwood. Unfortunately, I'm running a MC300 into my horns...

I do have a pair of 6550 mono tube heads in the closet that I could dig out. But it could get messy...

DM

[D-MAN]

This is always a sticky wicket...

The "tube" sound should be discussed. Here's what I think it is...

I would regard "tube" sound as having a tendency to round the leading and trailing edge of a given waveform as compared to amp that produces a realistic rendition of the actual waveform. There are, however, tube amps that do not alter the waveform as above, and therefore, the "tube" sound would not be apparent in such a case.

The speakers of any type cannot produce anything near the actual waveform, and they all tend to round the edges due to inertia, air resistance and the laws governing mechanical motion.

So I suppose that speakers that round the waveforms less are better than the ones that do more of it. Compression horns tend to have a better transient response (that is, the response to quick "spikes" of signal) than non-compression drivers due to the smaller diaphragms involved. Horn couplers, in turn, also increase the efficiency of whatever is attached to them, esentially acting as acoustic transformers from the driver to the atmosphere, so the net effect in the case of a fully-loaded horn speaker is:

1) enhanced response to transients (short duration signals)

2) increased efficiency (higher acoustic output per electical watt input)

3) less "rounding" of waveforms due to less mechanical resistance

Therefore, I would say that ANY all-compression loaded horn speaker would be more "tube" friendly in that the typical rounding of the waveform coming from the tube amp would not be "added" to by the speaker. This is assuming the case where an amp is producing a "tube" modified signal.

And that is not to say that all horn loudspeakers present the same quality of sound...

DM

[hoggy]

1st you'd have to figure out how many peanuts it takes to make the peanut butter than convert the peanut butter to patato chips and on and on and so forth. Or vise-versy. D-ManLynnwoods not that far but to tell the truth I love the way my Khorns sound with my Mac and if tubes in fact do make that much differnce for the better why are you using your Mac instead? Just curious?

hoggy