[rollo]

  Advantages and disadvantages of the designs have embattled designers for years. What is your circuit choice and why ? Is it distortion preference ? phase splitting issues ? noise ? Power ? All of the above and more ?

charles

[Niteshade]

The first question is not about the amp, but these:

1. Speaker efficiency
2. Room size
3. What you like to listen to and how (LOUD, soft, etc...)


(Sorry to be a 'ball hog' but I love these questions!)

I would not say there are not any inherent disadvantages to SET, SEP, PP, PP-Parallel topologies. The disadvantages come into play when the amp is not interfaced with everything else correctly.

[poseidonsvoice]

The first question is not about the amp, but these:

1. Speaker efficiency
2. Room size
3. What you like to listen to and how (LOUD, soft, etc...)


(Sorry to be a 'ball hog' but I love these questions!)

I would not say there are not any inherent disadvantages to SET, SEP, PP, PP-Parallel topologies. The disadvantages come into play when the amp is not interfaced with everything else correctly.

  But I have an inkling that the OP was looking for 'theoretical' advantages and disadvantages given a fully optimized system.

Anand.

[rollo]

The first question is not about the amp, but these:

1. Speaker efficiency
2. Room size
3. What you like to listen to and how (LOUD, soft, etc...)


(Sorry to be a 'ball hog' but I love these questions!)

I would not say there are not any inherent disadvantages to SET, SEP, PP, PP-Parallel topologies. The disadvantages come into play when the amp is not interfaced with everything else correctly.

I am takling about circuit design not choice of type for ones use. You have no preference for either. Those three criteria are the only reason for a design choice ? If ya gonna be a ball hog answer the question, I love these answers.

charles

[Niteshade]

Those criteria take priority over the design selection. Reason being that those questions can severely limit your topology choices.

If you were to start from scratch: Buy a new amp and speakers and have a room that's around 15x20 feet or so, I would recommend speakers that were at least 90db efficient and a push-pull amplifier of around 60 watts.  If you wanted more amplifier choices with the same room size, then go with at least 95db efficient speakers.  Now you can choose single ended, singled ended parallel and your smaller push-pull amplifiers. I am referencing to rock & roll, bluegrass or country music played at moderately loud volumes. I can 100% guarantee anybody that room size, listening volume,speaker type & efficiency and music genre listened to take priority over the amp design (initially).

If you have speakers in the 95+db range, you will have the best topology selection. I personally prefer SEP and push-pull amps. Their the most versatile and provide the most performance per dollar. Favorite tubes: 6L6, EL34 & 6550.

[FullRangeMan]

NiteShade argument looks good.  I would suggest this Klipsch RF83, two way 100dB SPL speaker to play with such amp:
  http://www.klipsch.com/na-en/products/rf-83-overview/

[Wind Chaser]

Based on my limited experience with a couple of EL84 and 2A3 amps, I prefer the sonic attributes of the SET over PP.  I like the power of PP, but the refinement of the SET is more important to my ear.  But as Niteshade implied, the choice of speakers with a SET becomes an issue.

[Niteshade]

Now you're talking! 

Their incredible performers for the price and can handle allot of power even though they are efficient. No need for a sub with these things! They perform better than the spec's suggest.

NiteShade argument looks good.  I would suggest this Klipsch RF83, two way 100dB SPL speaker to play with such amp:
  http://www.klipsch.com/na-en/products/rf-83-overview/

[FullRangeMan]

Now you're talking! 

Their incredible performers for the price and can handle allot of power even though they are efficient. No see for a sub with these things! They perform better than the spec's suggest.

Hello,
On a Brazilian forum there is a Club of this brand and the overall opinion is this RF83 is a stunning speaker for music,
they said the bass is Texas size and very good quality.
Regards, Gustavo

[Wind Chaser]

Klipsch RF83, two way 100dB SPL

My understanding is that spec of sensitivity / efficiency is overstated.

[JakeJ]

Based on my limited experience with a couple of EL84 and 2A3 amps, I prefer the sonic attributes of the SET over PP.  I like the power of PP, but the refinement of the SET is more important to my ear.  But as Niteshade implied, the choice of speakers with a SET becomes an issue.

This why I feel Single-Ended Push Pull is a better solution.  All the glory of triode but with power and lower distortion.  I have poured over several technical papers and the common theme is that SET will have unacceptable distortion figures when pushed to it's limits.  Of course the answer might be that if you want to run a 300B SET amp that will max at 9 Watts then you have to use a speaker that only needs 4.5 Watts.  History would seem to support my position as I found most early PA and theater amps used triodes in push-pull or parallel.  The SET amps seemed to be relegated to table radios and were definitely designed to a price point.
 
OK, let the tomatoes fly. 

[JoshK]

RF83's say it is rated to 29hz, says its 100db/2.83v/1m and it isn't the size of a fridge.  I like how they managed to get around a little incovenience called physics.

[FullRangeMan]

Hi Boys,
I see the rated efficiency of speakers as the average of the SPL range, not the efficiency in a bass point, treble or the entirely freq range.
But I can be wrong.
Klipsch looks a honest Company to me, IF you have any info say otherwise, please fell free to inform me as this RF83 is in my Wish List.
Regards, Gustavo

[rollo]

 Over the years we have owned PP Triode, SET and SS PP. To our ears the SET is a non fatigueing sound. Yes speaker choices are limited and can get quite expensive when power is needed.
  The speakeres we use have a sensitivity of 96db. With the darTZeel SS amp plenrt of thrills power and a high fi show. With the SET a relaxing affair with body and soul. Yes the bass is a bit rounder the highs maybe not as extentended but the midrange is more natural and emotional.
  Is it the phase splitting of the PP vs SET. Lets take Humpty Dumpty as an example. No matter how well he is put back together he is pot the same as before he fell. Now SET does have more disortion and power supply noise issues which require filtering of the mains. The distortion of the SET is more agreeable to our senses than PP which can come across as bright or hard sounding.
 At one of our meetings the hostwas driving Maggies with a sacreligous 8 watts. A definite no no with Maggies. Right ? Wrong.   The sound was glorious until clipping. Now the VTL 150s drove the Maggies much better but the tonality and harmonic stucture was MIA compared to the SET. For low to med volume and accomodating music selection most perferred the SET sound as limited as it was.
  I believe in the KISS theory. Why would a designer want to split the single, play with feedback and hope to reasemble the original input signal. 
  Are we building a better mousetrap or asking for complicated solutions?


charles

[JoshK]

Hi Boys,
I see the rated efficiency of speakers as the average of the SPL range, not the efficiency in a bass point, treble or the entirely freq range.

If that is the case, then they don't go to 29hz.  You can have 100db in one range and -3db at the bass point without having sensivity be, well down only -3db at the lower corner. 

They might be fine sounding speakers, I was calling out BS specs.

[Niteshade]

They are very,very,very good sounding speakers! The bass response is simply incredible and everything they do is effortless. A three watt low bass note will rattle the room. It's far from mushy or wobbly as well.

Are the spec's bogus? I can't say. Could you explain your reason?

[FullRangeMan]

Over the years we have owned PP Triode, SET and SS PP. To our ears the SET is a non fatigueing sound. Yes speaker choices are limited and can get quite expensive when power is needed.
  The speakeres we use have a sensitivity of 96db. With the darTZeel SS amp plenrt of thrills power and a high fi show. With the SET a relaxing affair with body and soul. Yes the bass is a bit rounder the highs maybe not as extentended but the midrange is more natural and emotional.
  Is it the phase splitting of the PP vs SET. Lets take Humpty Dumpty as an example. No matter how well he is put back together he is pot the same as before he fell. Now SET does have more disortion and power supply noise issues which require filtering of the mains. The distortion of the SET is more agreeable to our senses than PP which can come across as bright or hard sounding.
 At one of our meetings the hostwas driving Maggies with a sacreligous 8 watts. A definite no no with Maggies. Right ? Wrong.   The sound was glorious until clipping. Now the VTL 150s drove the Maggies much better but the tonality and harmonic stucture was MIA compared to the SET. For low to med volume and accomodating music selection most perferred the SET sound as limited as it was.
  I believe in the KISS theory. Why would a designer want to split the single, play with feedback and hope to reasemble the original input signal. 
  Are we building a better mousetrap or asking for complicated solutions?


charles

HI Rollo,
Your testimony call my attention, I will look more closely to SET amps to have a first hand(ear) opinion.
Thanks, Gustavo

[Niteshade]

A push-pull amplifier designed properly is actually incredibly detailed, not harsh and does not overly process audio. Think of it this way: There is a big job to do, like cleaning out the basement. It goes by faster with two people than with one. Push-pull splits the load and the increased system efficiency actually makes the system sound better, not worse. SET's are great for undemanding jobs. The KISS design process holds for Single ended & push pull circuits and has the same result: better sound. Feedback is something that is at times necessary BUT amplifiers can be designed so that they do not require much of it. I have heard systems where it's abused and it sounds awful and others where it was 100% beneficial, worked as it should AND worked flawlessly.

Never blame the tools for performance issues (as long as the tools/methods are sound). Always blame how they are used.

Over the years we have owned PP Triode, SET and SS PP. To our ears the SET is a non fatigueing sound. Yes speaker choices are limited and can get quite expensive when power is needed.
  The speakeres we use have a sensitivity of 96db. With the darTZeel SS amp plenrt of thrills power and a high fi show. With the SET a relaxing affair with body and soul. Yes the bass is a bit rounder the highs maybe not as extentended but the midrange is more natural and emotional.
  Is it the phase splitting of the PP vs SET. Lets take Humpty Dumpty as an example. No matter how well he is put back together he is pot the same as before he fell. Now SET does have more disortion and power supply noise issues which require filtering of the mains. The distortion of the SET is more agreeable to our senses than PP which can come across as bright or hard sounding.
 At one of our meetings the hostwas driving Maggies with a sacreligous 8 watts. A definite no no with Maggies. Right ? Wrong.   The sound was glorious until clipping. Now the VTL 150s drove the Maggies much better but the tonality and harmonic stucture was MIA compared to the SET. For low to med volume and accomodating music selection most perferred the SET sound as limited as it was.
  I believe in the KISS theory. Why would a designer want to split the single, play with feedback and hope to reasemble the original input signal. 
  Are we building a better mousetrap or asking for complicated solutions?


charles

[JoshK]

They are very,very,very good sounding speakers! The bass response is simply incredible and everything they do is effortless. A three watt low bass note will rattle the room. It's far from mushy or wobbly as well.

Are the spec's bogus? I can't say. Could you explain your reason?

Look up hoffman's iron law.  Then get a copy of unibox and play around with drivers in tuned boxes and see if you can replicate anything even remotely close to these numbers. 

The only thing I know that can hit 29hz @ 97db (-3db down from 100db rated) would be in the sub horns in the 400+L neighborhood, which those speakers clearly are not. 

[Niteshade]

This is interesting: http://www.audioholics.com/reviews/speakers/floorstanding/von-schweikert-vr2/page-4

These are much smaller speakers and have a response of 20-20,000hz. Their sensitivity is low, but they will cover the advertised frequencies. I like them, but they are somewhat hard to drive and not as forward & engaging as RF-83's.