SET amp owners thread

[morricab]

Horns are simple. Once you have those high quality drivers and core design which has been proven over decades nothing fancy is required The fanciness is only for new manufacturers to try something distinct, which is usually they screw up.

Horns are many things but simple is not one of them. I think the classic compression drivers were excellent (although some of the better modern ones are just as good) but the older diffraction horn designs have been surpassed by more modern designs use computer modeling to remove resonances that color the tonality.

 

[morricab]

It's called the Gedlee Metric.

It's based on two papers published by Earl Geddes and Lydia Lee:

http://www.gedlee.com/Papers/Distortion_AES_I.pdf

http://www.gedlee.com/Papers/Distortion_AES_II.pdf

As he was finishing up writing the papers, Earl remarked to me: "Now I know why you and your friends like tube amps."

For a long time I had heard Geddes did think distortion in amps mattered but then they did this work and I guess it changed his view somewhat.

 

[morricab]

if you don’t think hifi has progressed since the 40s, then we can agree to disagree. The irony is you want Be Radian tweeter horns in your diy job.

We have *much* better materials science and can eliminate distortion to a vastly superior degree than before. Iirc, JBL themselves spent several million developing the M2 horn.

I know where Bonzo is coming from. Hear a real WE theater speaker from the 1930s or a replica system and you can doubt easily that there has been ANY progress in speakers at least on speakers. Of course they are huge...so shrinking for domestic use is what JBL and Altec did later.

That said , new materials can improve things somewhat...but not as much as one might assume given the investment.

 

[bonzo75]

Horns are many things but simple is not one of them. I think the classic compression drivers were excellent (although some of the better modern ones are just as good) but the older diffraction horn designs have been surpassed by more modern designs use computer modeling to remove resonances that color the tonality.

Sorry, I was referring to the whole horn speaker which is what I thought Keith referred to. But with horns, yes. For example, wooden Altec multicell replicas and the autotech designs are quite better than most older ones

 

[Alrainbow]

Whats the

A whole bunch of modern pro drivers use very stiff suspensions still with hardly any throw. The dynamikks speakers we sell use such drivers. Even the 10 inch woofer in our Athos 10 is very stiff but produces deep and powerful bass while looking like it isn’t moving at all! It is a speaker using modern pro drivers.

Interesting , Whats the Xmax on them ..?

 

[Alrainbow]

A whole bunch of modern pro drivers use very stiff suspensions still with hardly any throw. The dynamikks speakers we sell use such drivers. Even the 10 inch woofer in our Athos 10 is very stiff but produces deep and powerful bass while looking like it isn’t moving at all! It is a speaker using modern pro drivers.

These : https://dynamikks.de/athos-10-kopie.html

 

[Rob181]

These : https://dynamikks.de/athos-10-kopie.html

That would be them - would love the have a listen to the new version of the Monitor series...

 

[Duke LeJeune]

For a long time I had heard Geddes did think distortion in amps mattered but then they did this work and I guess it changed his view somewhat.

Earl's data indicated that a very large amount of low-order distortion - 2nd order, maybe something like 15% or 25% - was only borderline detectable and was not objectionable. Overall his finding showed a slightly negative correlation between THD and preference, indicating that (as a generalization) higher THD amps tend to sound better than low THD amps. He found that the distortion and noise as the signal passed through the zero point tend to be audible and objectionable, because these (virtually instantaneous) anomalies are not "masked" by other sounds. Distortions which are delayed in time relative to the main signal - which (if I understand correctly) is what happens with large amounts of global negative feedback - also tend to be audible and objectionable, even in small amounts. I'm neither math enough nor brain enough to understand exactly what he looked at and how he analyzed his findings to arrive at his conclusions, so these are my recollections from conversations with him.

At some point along the way, but NOT as part of the study he did for these papers, Earl measured a bunch of amplifiers he had access to and found a particular Pioneer receiver to perform exceptionally well based on the Gedlee metric. Its published specs were unremarkable as I recall; in other words, there was no hint of hidden excellence in the numbers. He used one of these receivers for many years, and may be using it still. No I don't remember the model number, and it has been discontinued, but it developed sort of an underground cult following, and audiophiles being what they are, many were hotrodded with various upgrades.

To outsiders "Earl Geddes uses a cheap Pioneer receiver" probably sounded like "Earl doesn't care about distortion in amps", but I think the truth was more like "Earl thinks distortion figures for amps are useless as predictors of sound quality."

(And while I've seen people seemingly assume that Earl listens by looking at measurements, I have watched him listen critically. I have never seen someone so intensely focused on the task of LISTENING before or since, though he would never include his own listening impressions in his data because if he knows what he's listening for then he is not free from potential bias.)

All of that being said, I am not under the impression that Earl thinks amplifier sound quality is a major issue, at least not relative to the sound quality variations in loudspeakers.

 

[morricab]

These : https://dynamikks.de/athos-10-kopie.html

Yep those. These compact speakers really pack a punch.

 

[Duke LeJeune]

Yep those. These compact speakers really pack a punch.

Just took a look at the picture. Four inch voice coil, I assume? If so, that 10" woofer is a little monster!!

 

[morricab]

Just took a look at the picture. Four inch voice coil, I assume? If so, that 10" woofer is a little monster!!

3 inch vc, 105 oz magnet, 7.2 mm linear Xmas. Qts 0.28.

 

[Duke LeJeune]

3 inch vc, 105 oz magnet, 7.2 mm linear Xmas. Qts 0.28.

That big dustcap threw me off, but it's still a beast! Obviously it has a very powerful motor, with a Qts of .28.

 

[morricab]

That big dustcap threw me off, but it's still a beast! Obviously it has a very powerful motor, with a Qts of .28.

I guess it is improving stiffness? It is SET friendly despite only a 91db overall sensitivity. We got good results from an 11 watt SEP (single ended Pentode) in a smallish room

 

[morricab]

Earl's data indicated that a very large amount of low-order distortion - 2nd order, maybe something like 15% or 25% - was only borderline detectable and was not objectionable. Overall his finding showed a slightly negative correlation between THD and preference, indicating that (as a generalization) higher THD amps tend to sound better than low THD amps. He found that the distortion and noise as the signal passed through the zero point tend to be audible and objectionable, because these (virtually instantaneous) anomalies are not "masked" by other sounds. Distortions which are delayed in time relative to the main signal - which (if I understand correctly) is what happens with large amounts of global negative feedback - also tend to be audible and objectionable, even in small amounts. I'm neither math enough nor brain enough to understand exactly what he looked at and how he analyzed his findings to arrive at his conclusions, so these are my recollections from conversations with him.

At some point along the way, but NOT as part of the study he did for these papers, Earl measured a bunch of amplifiers he had access to and found a particular Pioneer receiver to perform exceptionally well based on the Gedlee metric. Its published specs were unremarkable as I recall; in other words, there was no hint of hidden excellence in the numbers. He used one of these receivers for many years, and may be using it still. No I don't remember the model number, and it has been discontinued, but it developed sort of an underground cult following, and audiophiles being what they are, many were hotrodded with various upgrades.

To outsiders "Earl Geddes uses a cheap Pioneer receiver" probably sounded like "Earl doesn't care about distortion in amps", but I think the truth was more like "Earl thinks distortion figures for amps are useless as predictors of sound quality."

(And while I've seen people seemingly assume that Earl listens by looking at measurements, I have watched him listen critically. I have never seen someone so intensely focused on the task of LISTENING before or since, though he would never include his own listening impressions in his data because if he knows what he's listening for then he is not free from potential bias.)

All of that being said, I am not under the impression that Earl thinks amplifier sound quality is a major issue, at least not relative to the sound quality variations in loudspeakers.

The last point you made, "I am not under the impression that Earl thinks amplifier sound quality is a major issue" is where I depart from Earl's point of view. I have heard awesome speakers be completely ruined by poor or mediocre electronics. The speaker might make the most distortion overall but it is not typically the most offensive type of distortion sonically. Linear distotions in particular are easy for the ears to adapt to to the point where people can like and live with all sorts of distortion of this type. The non-linearity typically found in speakers is likewise low order and monotonic, with the exception of things like cabinet resonance and driver breakups...both of which can be fatal to a speaker design but the better ones have under control. Conversely, I have heard what were considered mediocre speakers suddenly sing beautifully when hooked up to really top notch electronics.

It is my opinion these synthetic, electronic distortions (including effects from power quality) are inherently unnatural and therefore not accounted for by evolutionary development of our hearing and so standout like a sore thumb even at extremely low levels (jitter is another good example) whereas a speaker is a fundamentally mechanical thing that makes largely mechanical resonances and distortions that we can adapt to more easily (although crossover effects can be quite nasty due to phase and time misalignment in addition to FR issues).

 

[Atmasphere]

Earl's data indicated that a very large amount of low-order distortion - 2nd order, maybe something like 15% or 25% - was only borderline detectable and was not objectionable. Overall his finding showed a slightly negative correlation between THD and preference, indicating that (as a generalization) higher THD amps tend to sound better than low THD amps. He found that the distortion and noise as the signal passed through the zero point tend to be audible and objectionable, because these (virtually instantaneous) anomalies are not "masked" by other sounds. Distortions which are delayed in time relative to the main signal - which (if I understand correctly) is what happens with large amounts of global negative feedback - also tend to be audible and objectionable, even in small amounts. I'm neither math enough nor brain enough to understand exactly what he looked at and how he analyzed his findings to arrive at his conclusions, so these are my recollections from conversations with him.

At some point along the way, but NOT as part of the study he did for these papers, Earl measured a bunch of amplifiers he had access to and found a particular Pioneer receiver to perform exceptionally well based on the Gedlee metric. Its published specs were unremarkable as I recall; in other words, there was no hint of hidden excellence in the numbers. He used one of these receivers for many years, and may be using it still. No I don't remember the model number, and it has been discontinued, but it developed sort of an underground cult following, and audiophiles being what they are, many were hotrodded with various upgrades.

To outsiders "Earl Geddes uses a cheap Pioneer receiver" probably sounded like "Earl doesn't care about distortion in amps", but I think the truth was more like "Earl thinks distortion figures for amps are useless as predictors of sound quality."

(And while I've seen people seemingly assume that Earl listens by looking at measurements, I have watched him listen critically. I have never seen someone so intensely focused on the task of LISTENING before or since, though he would never include his own listening impressions in his data because if he knows what he's listening for then he is not free from potential bias.)

All of that being said, I am not under the impression that Earl thinks amplifier sound quality is a major issue, at least not relative to the sound quality variations in loudspeakers.

Another amplifier that would appear to measure well by the Geddes method might be the Realistic SA175C which is a 6-watt amp. It and its brethren (SA100C, SA101) employ a 4-transistor power amp circuit that uses a fair amount of capacitive coupling. The circuit is entirely single-ended until the output transistors and so makes a fair amount of 2nd harmonic. As long as you don't push them hard these amps can sound quite sweet (although to really hear what they do they have to be refurbished and the loudness contour defeated) and smooth- I'm assuming because the 2nd harmonic is doing a fair amount of masking of the higher orders. Sunn made a solid state guitar amp back in the early 70s that employed a zero feedback fet preamp section, driving a single ended voltage and driver circuit, which only went to push-pull via a sizable interstage transformer. This amp also makes a fair amount of 2nd ordered harmonic and is known amoungst guitar players as one of the richer sounding solid state amps.

 

[Exlibris]

Ah, I see...could be quite a wait then...Odeon is not the most "user friendly" company...

I received an update yesterday. The Odeon 33s that I ordered should be ready next week. The shipment is coming by sea so I might have them by mid to late August.

 

[morricab]

I received an update yesterday. The Odeon 33s that I ordered should be ready next week. The shipment is coming by sea so I might have them by mid to late August.

You sure are a patient man...

 

[snopro]

Coincident Technologies Frankenstein 300b Mk.2 monos with Takatsuki TA-300b tubes driving Horning Eufrodite Ellipse speakers

 

[morricab]

Coincident Technologies Frankenstein 300b Mk.2 monos with Takatsuki TA-300b tubes driving Horning Eufrodite Ellipse speakers

How do you like those Eufrodites? I was thinking about these speakers.

 

[dwhistance]

Going back to the original post I'm using an SJS Arcadia (Simon Shilton) PSE 2A3 amp with Ocellia Grandis Calliope Signature 30 Twin speakers. The amp has been modified by taking out a gain stage so it is currently WE 417A driving the 2A3's. I'm using RCA JAN 2A3 valves. The combination is dynamic and revealing but still very musical.