High Efficiency Speaker Asylum

Need speakers that can rock with just one watt? You found da place.

Return to High Efficiency Speaker Asylum


Message Sort: Post Order or Asylum Reverse Threaded

If it is high level HD.....

106.203.99.90

Posted on November 19, 2020 at 22:17:14
Bill the K
Audiophile

Posts: 7892
Joined: June 3, 2006
that makes SET amps so likeable and musical, then why not some designers put their heads together and come up with a manipulated speaker that plays the high level HD distortion? Then everybody will have the benefit of owning a SET amp without going for one and can get the same Serotonin in the brain thru the new speaker. Ideally it could be a small attachment to the crossover or somewhere so that we can use our present speakers. I am not sure if this speaker will turn out to be an active speaker with a SET built in. That will defeat the purpose.

Cheers

Bill

 

Hide full thread outline!
    ...
RE: If it is high level HD....., posted on November 20, 2020 at 05:18:23
Bill Fitzmaurice
Industry Professional

Posts: 4991
Location: New England
Joined: October 20, 2002
It's not high level THD, it's a combination of moderate THD plus compression. To some extent it can be duplicated electronically, that's what electric guitar modeling pre-amps and amps do. It can't be duplicated mechanically.

 

on the other hand, HD levels of most loudspeakers is high, posted on November 20, 2020 at 07:01:49
mhardy6647
Audiophile

Posts: 13981
Location: New England
Joined: October 12, 1999
Contributor
  Since:
October 23, 2016

-- one or two orders of magnitude higher than the distortion of the upstream electronics chain.
And, at low frequencies, much of that HD is of the "euphonic" kind -- so-called "second harmonic" (i.e., one octave above the fundamental); oft referred to as "doubling" in the realm of woofers.
I don't think (FWIW) that euphonic HD is what makes a good SE(T) amplifier sound good.

The example above from ASR is randomly, arbitrarily, and slightly somewhat misleadingly chosen. ;) It is a small, inexpensive loudspeaker. Note that at very low frequencies (30 Hz), the (EDIT) THD is nearly 100%. Interstingly, it's mostly 3rd HD, though.


all the best,
mrh

 

RE: on the other hand, HD levels of most loudspeakers is high, posted on November 20, 2020 at 08:36:16
Bill Fitzmaurice
Industry Professional

Posts: 4991
Location: New England
Joined: October 20, 2002
The THD may approach 100% at 30hz, but I wouldn't be running that speaker lower than 80Hz.

 

RE: If it is high level HD....., posted on November 20, 2020 at 12:09:59
Paul Joppa
Industry Professional

Posts: 7025
Location: Seattle, WA
Joined: April 23, 2001
The first amplifier I built came from the pages of Popular Electronics, in 1962 I think - I was a teen at the time. It used the then-new "transistors." Powered by four D-cells, the speaker was the collector load, running DC through the speaker. This offsets the speaker cone, which increases even-order distortions.

We were living in a furnished rental house, which had a huge mono speaker in the corner of the house. It made quite satisfactory music. I've since wondered whether the cone offset contributed to the sound.

 

The SET "magic", posted on November 20, 2020 at 14:07:30
Brian H P
Audiophile

Posts: 760
Location: Oregon
Joined: December 18, 2012
comes from a combination of low output power, 1-5% SECOND harmonic distortion only (upper harmonics greatly reduced), a damping factor turned to mush and an unstable frequency response into variable speaker impedances caused by the high output transformer impedance, and somewhat rolled-off "sweet" highs. As Bill F notes, some of these characteristics may be "emulated" in solid-state, especially Class-D designs with DSP.

They are really only suitable for driving extremely high-sensitivity speakers, which tend to have very low distortion of their own, and whose frequency response errors (such as shrill edgy treble) they may somewhat compensate for. Such SET/horn combos can in fact sound quite euphonic and lovely, to the point where many audiophiles prefer their presentation to a more "accurate" performance.

 

I said it was misleading ;) (nt), posted on November 20, 2020 at 14:20:49
mhardy6647
Audiophile

Posts: 13981
Location: New England
Joined: October 12, 1999
Contributor
  Since:
October 23, 2016
nt
all the best,
mrh

 

RE: The SET "magic", posted on November 20, 2020 at 15:55:54
Cleantimestream
Audiophile

Posts: 7105
Location: Kentucky
Joined: June 30, 2005
Or, there is more to be learned/revealed on crossover distortion that is simply not known, ergo we do not know what to measure for. How does one account for the superior/seamless midrange easily heard in a properly built SET... mushy bass>? Perhaps you have not heard superb bass from a 45 to appreciate what it sounds like. Understand I have owned numerous >100,000 systems encompassing most engineering {still miss ion plasma tweeters}.
The Mind has No Firewall~ U.S. Army War College.

 

Bob Carver tweaked a SS amp to sound exacly like a CJ years ago..., posted on November 20, 2020 at 18:19:17
Rod M
Web Geek

Posts: 13217
Location: So. California
Joined: March 1, 1999
Contributor
  Since:
March 1, 1999
Try it:

To make your solid state amp sound more tube like, here is what you do, buy some 20 to 25 watt resistors like these http://www.electronicsurplus.com/vishay-dale-electronics-cpwn20-3-resistor-power-0-3-ohm-20w, then place only one resistor in series with one of your speaker terminals. Bob suggested buying 3 of these resistors (6 total) starting at 1/4 ohm, 1/2 ohm, and 1 ohm.

The more resistance you use, the more tube like your amp will become, however, past 1 ohm on most speakers, the bass will get sloppy past 1 ohm. The resistors can be inductive or non inductive, feel free to experiment with both kinds.


-Rod

 

RE: Bob Carver tweaked a SS amp to sound exacly like a CJ years ago..., posted on November 20, 2020 at 20:09:38
Paul Joppa
Industry Professional

Posts: 7025
Location: Seattle, WA
Joined: April 23, 2001
Some speakers (not many!) are designed for use with low-damping-factor amps.

Interestingly, it has the advantage of "cheating" on Hoffman's Iron Law; you can get a bit more efficiency from a bigger magnet on an otherwise-identical driver, in the same box.

 

RE: Bob Carver tweaked a SS amp to sound exacly like a CJ years ago..., posted on November 20, 2020 at 20:28:47
rivervalley817
Audiophile

Posts: 3586
Joined: June 15, 2020
if I remember the controversy correctly surrounding that claim Carver's concoction only reproduced the mid range and HF characteristics

regards,

 

RE: If it is high level HD....., posted on November 21, 2020 at 06:09:52
dave slagle
Manufacturer

Posts: 5209
Location: NYC
Joined: April 27, 2001
The cone offset is a casual curiosity to me. years ago I was using lowthers and while many insisted they were underhung I found many to actually be "even hung" where the length of the voice coil equalled the physical height of the gap. The way I found this out was from having the unassembled permandur parts of a PM4A and a PM-2A where I had demagnetized it. Fully understanding that the fringing flux would be asymmetrical with more emphasis or focus occurring at the bottom of the voice coil and given the very small X-max I would typically center the coils just below the top of the gap as a best guess for centered. Understanding that air was naturally asymmetrical I often wondered about purposely "off centering" the voice coil in the gap to combat this.

Enough of the back story... I build an autoformer output amp using PP 6C33's for an early NY Noize. and the 6C33's used power toroids with additional windings as autoformers in the anodes with a negative supply in the cathode. This put the center tap of the "secondary" at ground and in a perfect world with matched DCR's and currents there would be no DC offset. Well with 400ma of anode current, variability of the 6C33 and the nature of DCR's and windings, somewhere around 100-200mv of DC offset was had at the speakers. It was enough to visibly show a displacement of the lowther cone speaker when connected. Air is asymmetrical, it generates an even order distortion (patricularly lowthers in rear loaded horns) and the phase of the drive from a 2W SE amp is clearly audible in the bass. The interesting thing about the PP 6C33 amp was it showed a similar effect with phase even though the even order distortions were minimal. My thoughts at the time had the DC offset of the driver placing the cone in the asymmetrical flux path (even order distortion generator) and depending on which way the DC offset was phased this could either add to or "cancel" the distortion of air in the rear loaded horn.

Ultimately the amp was PP and used 6C33's both of which I find have little musical character so after the show the amp was pulled off its wheels cut apart and put back into the parts bin. I do recall about a decade later looking at some underhung vintage compression drivers and noticing that the voice coils were not centered in the gap. It was a stereo pair from different vintages so I surmised the offset was indeed intentional to combat the vastly different pressures on either side of the diaphragm. This got me musing about adding a variable DC offset to tweak the voice coil positioning and that idea still remains on my to-do list.

dave

 

RE: Bob Carver tweaked a SS amp to sound exacly like a CJ years ago..., posted on November 21, 2020 at 06:33:31
Bill Fitzmaurice
Industry Professional

Posts: 4991
Location: New England
Joined: October 20, 2002
Carver's concoction didn't duplicate tuba amp characteristics when said tube amp is pushed past its linear response capabilities. It's the same reason why a 50 watt 6L6 push-pull doesn't sound like a 3 watt SET at the same volume.

 

RE: Bob Carver tweaked a SS amp to sound exacly like a CJ years ago..., posted on November 21, 2020 at 13:40:03
rivervalley817
Audiophile

Posts: 3586
Joined: June 15, 2020
sounds like the real world to me

'tuba amp' ; )

... I'm stealing that

regards,

 

"superior/seamless midrange", posted on November 21, 2020 at 16:05:17
b.l.zeebub
Audiophile

Posts: 7677
Location: 52deg 28'N,1deg56'W
Joined: April 17, 2006
That is your 2nd Order distortion in action.

Some people like that, others don't. It is not HiFi though.

 

RE: Bob Carver tweaked a SS amp to sound exacly like a CJ years ago..., posted on November 21, 2020 at 19:13:23
hahax@verizon.net
Audiophile

Posts: 3729
Location: New Jersey
Joined: March 22, 2006
I have spoken with Gordon Holt about the process and he assured me Carver accomplished what he claimed.

 

RE: "superior/seamless midrange", posted on November 22, 2020 at 00:41:08
91derlust
Audiophile

Posts: 963
Joined: December 25, 2014
Why do you say that must be due to H2 distortion? Why not the lack of crossover distortion or near-absence of higher-order harmonics?

I suspect confirmation and loss aversion biases are at play in these discussions. I'd like to see the evidence of the levels of the different types and combinations of distortion listeners can reliably identify, or even just get a sense of with non-critical listening. Certainly in no way definitive, I recall one well-regarded SS amplifier designer pegging it at roughly 2% for H2 distortion; some listeners will be more sensitive and others less.

I've observed what I think was H2 distortion when driving some moderate efficiency speakers with my previous 2A3 SET to almost-loud levels; I did not like that sonic imprint at all. I have not experienced that with my current 2A3 SET and higher efficiency speakers. On those rare occasional I listen loud, my amp is probably producing 1W with peaks. When listening at normal levels, my amp is probably producing low 100ths of Watt, with peaks in the low 10ths of a Watt, if that. I suspect distortion is pretty low at those levels. Sounds fine.

I still enjoy higher power / lower efficiency systems too... I even like my Metaxas amp driving the high efficiency speakers. Go figure.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

Speaker driver or speaker box?, posted on November 23, 2020 at 06:03:39
Ivan303
Audiophile

Posts: 41701
Location: Cadiere d'azur FRANCE - Santa Fe, NM
Joined: February 26, 2001
Horns?

How does one know?

What speaker measurements tell the tale?

Thanks.



 

RE: Speaker driver or speaker box?, posted on November 23, 2020 at 06:13:12
Bill Fitzmaurice
Industry Professional

Posts: 4991
Location: New England
Joined: October 20, 2002
As I recall it was a totally subjective listening test. That makes the conclusions drawn suspect. Watch this video starting at the 2:45 marker.

 

RE: If it is high level HD....., posted on November 23, 2020 at 11:20:30
Paul Eizik
Audiophile

Posts: 2064
Joined: September 15, 2001
Back in the early/mid 90's Sound Practices magazine exploded on the scene with the then outrageous idea that the SET was the best amplifier topology, with horns as the default preferred speaker type for them. It was interesting to see this play out in the audio magazines at the time. Stereophile's John Atkinson declared the first SET they tested "...a tone control..". One of the best articles about the then new (outside of Japan) SET craze was in Audio magazine, now unfortunately gone. Among the usual tests and discussions thereof about the harmonic distortion spectrum of various amps, the author included slew rate tests of the 300B SET he used for the article. He found that the slew rate performance of this 8 Watt amp was surprisingly good, and stated that you would have needed a 90 Watt class A transistor amp to equal it. I haven't noticed any other discussion of this, but it certainly begs the question of the audibility of slew rate performance and how it contributes to the SET sound. At an audio show in the late 90's I heard one of Nelson Pass's Aleph transistor amps which sounded more tube like than some of the actual tube amps at the show. So I don't know if an add on is needed, you just pick your speakers and then the amp to match, though Sound Practices seemed to start with the SET amps which then picked the horns for them.

Paul

 

RE: "superior/seamless midrange", posted on November 23, 2020 at 11:35:36
Retsel
Audiophile

Posts: 1180
Joined: April 17, 2000
Can I presume that you were never swooned by the wonderful prose by the late Harvey "Gizmo" Rosenberg who raved about the sound of directly heated triodes? It is hard not to at least be infected by his passion on the issue, even if you never bought into his poetic claims.

The distortion of DHT amps is low provided that the speakers are sufficiently efficient. I use 300B amps on Lowthers in front waveguides, which I suspect are over 100 db efficient. I do use sand amps below 500 hz for the woofer (Bryston) and subwoofer (Hafler), so I am inbetween I guess.

I tried my Hafler P7000 on the Lowthers and removed it as fast as I put it in, and it certainly was NOT because the Hafler was lower in distortion... What a God awful sound that combination made, sheeesh. I would like to try a First Watt amp at some point. I have read the comments of many who prefer their SE amps to the First Watt amps, but there are also many who do like the combination.

Retsel

 

RE: Speaker driver or speaker box?, posted on November 23, 2020 at 13:13:39
Paul Joppa
Industry Professional

Posts: 7025
Location: Seattle, WA
Joined: April 23, 2001
Apologies - I have corrected my post.

 

Curious about what speaker characteristics , posted on November 23, 2020 at 13:20:59
Ivan303
Audiophile

Posts: 41701
Location: Cadiere d'azur FRANCE - Santa Fe, NM
Joined: February 26, 2001
might make it more suited for low damping factor amps.

Bigger magnets?

Sensitivity?

Boxes vs. horns?

If it's magnet size, guessing the JBL 2441's on Edgar 'salad bowls' should qualify?






 

RE: Curious about what speaker characteristics , posted on November 23, 2020 at 20:24:33
Paul Joppa
Industry Professional

Posts: 7025
Location: Seattle, WA
Joined: April 23, 2001
In this case, I'm just talking about bass. The low damping factor raises the effective Q of the driver, while a bigger magnet decreases it. So you can make the same alignment in the same box with the same cone, while the larger magnet increases the efficiency.

As I understand it, in the early post-WWII days many speakers were maximum efficiency designs with huge magnets and a low Q. This made them suitable for bass horns, but as direct radiators their Q was too low to get deep bass. A solution was unity damping (output impedance of the amp was equal to the driver's DCR), and there were several amplifiers that used a mix of positive and negative feedback to create unity damping, usually with a switch to choose between high damping and unity damping.

 

RE: Curious about what speaker characteristics , posted on November 23, 2020 at 21:27:32
91derlust
Audiophile

Posts: 963
Joined: December 25, 2014
My simple take is that amplifiers and speakers form a system: factor the amplifier output impedance into the design of the speaker. SET (in combination with a speaker) bass need not be "mushy" as some claim.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

RE: "superior/seamless midrange", posted on November 24, 2020 at 03:56:19
b.l.zeebub
Audiophile

Posts: 7677
Location: 52deg 28'N,1deg56'W
Joined: April 17, 2006
I was never swayed by any tube amp and Lowthers are the worst speakers I have ever heard in over 40 years.

 

RE: "superior/seamless midrange", posted on November 24, 2020 at 06:51:33
Tom Brennan
Audiophile

Posts: 5681
Joined: January 2, 2000
The greatest audiophile skill is finding gear with complimentary faults.

 

RE: "superior/seamless midrange", posted on November 27, 2020 at 04:06:55
b.l.zeebub
Audiophile

Posts: 7677
Location: 52deg 28'N,1deg56'W
Joined: April 17, 2006
It is impossible to make Lowthers sound acceptable with judicious component choice, they are far too bad for that.

 

RE: "superior/seamless midrange", posted on November 27, 2020 at 21:16:28
Tom Brennan
Audiophile

Posts: 5681
Joined: January 2, 2000
I heard some good sounding Lowthers, Alan Hendler's for instance. And I heard some bad ones too. Given the range of drivers Lowther makes and the various ways people load them I think general conclusions are not realistic.

 

Page processed in 0.041 seconds.