[Guy 13]

Hi Blair and all Audio Circle members.
I am fairly new with Audio Circle, have been mainly writing on GR Research site.
After spending hundred plus hours surfing on many audio sites, I came to the conclusion that every manufacturers claim that their products are the best, that they have found and they offer the best approach to the most realistic music reproduction, in addition most, but not all, of the owners of the manufacturers equipment claim that they have made the best choice.
Who to believe ? ? ?
The conclusions of my findings, which are far from being final or word of God, are that they are all good and each one has his own strength and weakness.
Like it or not, I will exclude from the above statement all the good and/or odd looking Chinese made amplifiers, even the ones made for well known American manufacturers. Of course there are some exceptions, but they remain exceptions.
That’s my opinion, for what it’s worth !
Now, can some one tell me with simple words what are the strengths and weaknesses of each of the below items:
(And if I forgot something, please ad it on.)

SE Triode :
SE Pentode :
Ultra linear :
Parallel tubes :
Push pull :
Power supply, double tube rectification (5U4) :
Power supply single tube rectification (5U4)
Solid state rectification :
Power supply chokes:
Power supply extra filtering capacitors:
Switching from tube to solid state (Diode) rectification:
Power supply 0C3 tube regulation:
DC filament:
(Which tubes will benefit the most and the least from that
option ?)
Tunable NFB (Negative feed back):
Tunable Bias:
Auto bias:
Large power supply for 6550, but used for 6L6:
Steel versus aluminum versus other metal chassis:
Separate power supply for pre-amp/phono stage and power section:
6L6 versus 6550/KT88 (Other than just more watts):
Am I wrong if I say that Class D solid state amplifier is better at the low end and tube amplification is better in the mids and hi ?
I know, that’s a lot of stuff to answer and/or comment, but no need to do it at once and all at the same time.
I think the above will not only benefit to me, but to many other Audio Circle members.
I have seen on Audio Circle, some topics that have only 10 answers and comments, but 800 plus members have viewed the topic, that means something.
I will be watching the evolution of my topic.
Have a nice day.
Guy 13
(Now in Vietnam, but from Montreal, Canada)
. . . . . . . . . . . . . . . . . . . . .

[Niteshade]

There are quite a few things in your list to digest all at once, so I will group them into separate posts. Anyone is welcome to join in.

It is a fair observation to say every manufacturer believes their equipment is the best.

The philosophy behind all of Niteshade Audio's products: Develop the best possible design around a component's strengths using as streamlined a circuit as possible. That means we use electronic devices in accordance to the best circuit position available to them. Using a component properly yields superior performance and naturally lends itself towards superior circuits.

What I consider inferior design properties:

1] When more components are used than are necessary to achieve good performance, relative to a streamlined circuits that can outperform it or at least perform as well.

2] Forcing a component to perform a duty it is not designed to perform. The result is an inferior circuit that, for example, could wear out tubes quickly.


The above philosophy has a bearing on my answers to some of your questions.

You forgot a category of tube technology: OTL

Power tube wiring configurations configurations:

The best is what is called a tetrode hookup. Triode and ultra-linear are technically inferior because they have to stress the tube in order to achieve high performance. The stress comes from higher idle current. As a result, the tube will produce less power per input watt. This issue should be avoided at all costs. Triode and ultra-linear hookups also reduce power supply filtering effectiveness. That is not good either.

Dual rectifiers: Permit double the current output of a single rectifier. We go by application to determine if this is best for your requirements since sonic attributes are modified going from single to double.

Parallel tubes: Reduce output impedance and increase output power capabilities in amps and preamps. The increased power output manifests itself as a stabler circuit during sustained high power demand as well as transient response performance. Wide bandwidth performance is also increased greatly.

Single ended output: One tube is used for the output stage per channel. Advantages include a reduction of components, less heat output and economical tube replacement. This configuration can be made light weight without a severe compromise in performance.

Push-Pull: Think of it as a children's see-saw. This is split-load amplification. One tube handles the negative part of an incoming wave while the other amplifies the positive. This is the most efficient way to design a high powered amplifier. When made properly, they are as clean and exact as single-ended amps. Another advantage to push-pull: They have natural noise canceling abilities unlike single ended amps.

OTL: Transformerless output: Multiple tubes or transistors are configured in a push-pull design that utilizes a bi-polar power supply that, when everything is balanced, eliminates DC current at the output. Like every other design, they have sonic attributes that people like. It is my opinion that OTL should be strictly in the realm of transistors. A circlotron implementation of the OTL philosophy is best implemented with tubes: An output transformer is used, however, there is little or NO DC current flowing through the transformer's primary leading to excellent performance AND a reduced parts count relative to an OTL circuit.

I will write more later on. Others are always welcome to jump in!


 

[Guy 13]

There are quite a few things in your list to digest all at once, so I will group them into separate posts. Anyone is welcome to join in.

It is a fair observation to say every manufacturer believes their equipment is the best.

The philosophy behind all of Niteshade Audio's products: Develop the best possible design around a component's strengths using as streamlined a circuit as possible. That means we use electronic devices in accordance to the best circuit position available to them. Using a component properly yields superior performance and naturally lends itself towards superior circuits.

What I consider inferior design properties:

1] When more components are used than are necessary to achieve good performance, relative to a streamlined circuits that can outperform it or at least perform as well.

2] Forcing a component to perform a duty it is not designed to perform. The result is an inferior circuit that, for example, could wear out tubes quickly.


The above philosophy has a bearing on my answers to some of your questions.

You forgot a category of tube technology: OTL

Power tube wiring configurations configurations:

The best is what is called a tetrode hookup. Triode and ultra-linear are technically inferior because they have to stress the tube in order to achieve high performance. The stress comes from higher idle current. As a result, the tube will produce less power per input watt. This issue should be avoided at all costs. Triode and ultra-linear hookups also reduce power supply filtering effectiveness. That is not good either.

Dual rectifiers: Permit double the current output of a single rectifier. We go by application to determine if this is best for your requirements since sonic attributes are modified going from single to double.

Parallel tubes: Reduce output impedance and increase output power capabilities in amps and preamps. The increased power output manifests itself as a stabler circuit during sustained high power demand as well as transient response performance. Wide bandwidth performance is also increased greatly.

Single ended output: One tube is used for the output stage per channel. Advantages include a reduction of components, less heat output and economical tube replacement. This configuration can be made light weight without a severe compromise in performance.

Push-Pull: Think of it as a children's see-saw. This is split-load amplification. One tube handles the negative part of an incoming wave while the other amplifies the positive. This is the most efficient way to design a high powered amplifier. When made properly, they are as clean and exact as single-ended amps. Another advantage to push-pull: They have natural noise canceling abilities unlike single ended amps.

OTL: Transformerless output: Multiple tubes or transistors are configured in a push-pull design that utilizes a bi-polar power supply that, when everything is balanced, eliminates DC current at the output. Like every other design, they have sonic attributes that people like. It is my opinion that OTL should be strictly in the realm of transistors. A circlotron implementation of the OTL philosophy is best implemented with tubes: An output transformer is used, however, there is little or NO DC current flowing through the transformer's primary leading to excellent performance AND a reduced parts count relative to an OTL circuit.

I will write more later on. Others are always welcome to jump in!

Triode, pentode, push pull, options and up grade ? ? ?
Re: Triode, pentode, push pull, options and up grade ? ? ?
There are quite a few things in your list to digest all at once, so I will group them into separate posts. Anyone is welcome to join in.
Sorry about that. I wanted to put everything under one post, so it won’t be scattered all over Audio Circle.
It is a fair observation to say every manufacturer believes their equipment is the best.

The philosophy behind all of Niteshade Audio's products: Develop the best possible design around a component's strengths using as streamlined a circuit as possible. That means we use electronic devices in accordance to the best circuit position available to them. Using a component properly yields superior performance and naturally lends itself towards superior circuits.

What I consider inferior design properties:

1] When more components are used than are necessary to achieve good performance, relative to a streamlined circuits that can outperform it or at least perform as well.

2] Forcing a component to perform a duty it is not designed to perform. The result is an unstable circuits that, for example, wears out tubes quickly.


The above philosophy has a bearing on my answers to some of your questions.

You forgot a category of tube technology: OTL
Yes, you are right, the reason for that involuntary omission is that the OTL technology never attracted me; therefore I have a tendency to forget about it…
Power tube wiring configurations configurations:

The best is what is called a tetrode hookup.
I wonder why so many audiophiles only swear by the DHT 300B (Triode) ? ? ? They claim that they get the most natural midrange for voices and acoustic instruments…
I kind of agree with them. Several times, I’ve listen to a 300B triode amplifier with Lowther DX-3 drivers in a horn enclosure, I was impressed buy all the details you get I’ve heard.   
Dual rectifiers:
I saw somewhere on Audio Circle that you use diodes rectification for the 60wpc amplifier, instead of two tubes, would it be better to go with diode rectification or double tube rectification for 30 and 60wpc ? Is double tube rectification making a (Big) difference on the sound and what kind of difference would that be ?
Parallel tubes:
If that’s the case, instead of a single 6L6 tube, why not two parallel 6V6, you would get about the same wattage with the benefits you mention above ?
Before experimenting with other configurations that’s the way I want to go first, it’s the lowest in price. 
Push-Pull:
It as been written many times, that it is very difficult to make a good : phase splitter or phase inverter (I hope I am using the correct terminology) and many manufacturers could not do it properly, some say it will always be inferior to SE. They say that McIntosh came very close to be perfect with their circuit, meaning, not degrading the sound…
OTL:
I don’t like the idea of a zillion tubes, mainly because of the heat it’s generating.
No sound degrading output transformer might be a good idea, but a well engineered and built transformer is a good and well proven approach, of course at Transcendent they will not agree with me, but that’s O.K. each one as the right to his own opinion and conviction. 
I will write more later on. Others are always welcome to jump in!
Of course, other people can joint, I am sure they might have something to share with us, isn’t that the purpose of Audio Circle.
Have a nice day.[/b]Guy 13 in Vietnam.
Blair Lamphear
Niteshade Audio

[BobRex]

Ummm Guy, please learn how to cleanly respond to postings.  Your responses to Blair gave me a headache trying to determine who was saying what.

Anyway,  I don't agree with everything Blair said, here are my opinions:

Triode vs Tetrode / Pentode - This depends on whay you want to hear.  Apples to apples Pentodes and Tetrodes typically give you more power.  As always, there are exceptions.  In my experience triodes sound "purer", with less grain and more of what Sam Tellig used to refer to as palpable presence.  BTW - if you like the sound of 300Bs, you should also listen to 2A3s or 45s, each one is more linear and extended than the typical 300B.

SE vs Parallel vs PP - There are times when be best circuit is the simplest circuit.  Again, SE is as simple as you can get.  Now the trick is, with only one output tube, you limit power and potentially bandwidth.  With parallel circuits you can increase power, but you have the potential for tube mis-match.  The audibility of this may be questionable (some people hear it, some don't.)  PP brings in the issue of phase splitters (which BTW don't have to be active devices, you can also use a transformer) and their issues.

OTL - Ralph Karsten has been making OTL amps for over 20 years.  They are reliable and rugged and sonically damned good.  The technology is sound (no pun intended.)  What Blair wrote makes little sense - Atma-sphere amps  are cyclotron amps and DO NOT have an output transformer; they also use triodes.  They aren't push pull, so I don't know where Blair gets his comments from.  BTW - you might want to investigate OTL, either Transcendent ot Atma-sphere, there are many member here that love what OTL does, and in fact, so does the press.

[Niteshade]

Futterman based OTL's are push-pull. A single ended OTL must have some kind of decoupling device to eliminate DC, such as a capacitor.

Circlotrons are similar to OTL's but use an output transformer.

OTL's can use any tube. Low impedance ones are the best of course.

Links:
http://circlotron.tripod.com/

http://webpages.charter.net/dawill/tmoranwms/Circuits/6AS7_Futterman_OTL.gif

[BobRex]

Blair, here is a quick cut from Ralph Karsten's web page (Atma-sphere.com/papers):

"In the 1960s and 1970s OTLs developed a reputation for unreliability, primarily due to a circuit developed by Julius Futterman and the later marketed by New York Audio Labs (Harvey Rosenburg). The Futterman circuit was for many years the most publicly visible OTL, and was known for stability issues (caused by positive feedback nested within a global negative feedback loop). When in oscillation, (which could be caused by overload, component failure or even layout problems), the amp had a tendency to destroy itself. For many years the public has associated the weaknesses of the Futterman circuit with OTLs in general. Fortunately modern OTLs have solved the earlier problems of the Futterman by (for the most part) using entirely different circuitry.

In fact, every manufacturer who has ever attempted to produce a Futterman amplifier has ultimately gone out of business. The public is very demanding of reliability. For 30 years, the 'Futterman legacy' has been the largest marketing issue any OTL manufacturer has had to face.

At this point no accurate history of OTLs can ignore Atma-Sphere Music Systems. Founded in August of 1977, Atma-Sphere was created around its radical new approach to OTL technology and a dedication to State of the Art in audio amplification.
 
Atma-Sphere's biggest claim to fame is the introduction of the world's first reliable and practical OTL. This was accomplished by using a fully symmetrical output circuit (known as the Circlotron; first devised in 1954 by Cecil Hall), which resulted in low distortion and 1/2 the output impedance. The low distortion means that little or no feedback is required, resulting in a very stable amplifier. Atma-Sphere is also the first to offer an OTL amplifier in a fully balanced (differential) configuration, allowing for balanced and single-ended inputs (and in fact offered the first balanced-line products for use in the home). A further innovation was the first use of a fully symmetrical driver circuit.

The design was quite successful; Atma-Sphere is now the largest and oldest manufacturer of OTLs worldwide.

There have been only three patents issued to OTL manufacturers since the 1950s; two of them belong to Atma-Sphere. "


There is more, of course, but I'll let you read the papers.  You are aware of Atma-sphere aren't you?

[Niteshade]

Yes, I am aware of that company. What they have done with OTL technology is nothing short of astounding. Futterman was a stepping stone and they have indeed improved that design several times over.

Call me stubborn, but I still believe the transformer-based circlotron is a better approach. Transformers increase circuit efficiency and that is why I like them. They provide a means to interface with speakers better. I do plan on designing a transformer based circlotron next year based on 6L6's or El34's.

I will never dispute what someone says they like. It would make little sense.

If someone wants a specific sound/tone quality, I will recommend which one of my amps or preamps best fits their needs and it will not include circuits I dislike, something I choose not to put my name on. Just recently I won over a customer who REALLY WANTED a triode-wired 6L6 amplifier. I would have made it for them, but I seriously advised against it, especially within the confines of the budget AND what they expected for performance. The individual has had this amp for a while now and I doubt triode mode will cross their mind again.

I do not like designs that have practicality issues even though ones like the OTL, certain triodes, some pentode circuits and various other things are interesting.

The bottom line: There is more than one way to get the sound and performance you want and it is wise to look at other avenues than the impractical for solutions. The end result will be a fatter bank account and more than likely a better product.

[Guy 13]

Ummm Guy, please learn how to cleanly respond to postings.  Your responses to Blair gave me a headache trying to determine who was saying what.

Anyway,  I don't agree with everything Blair said, here are my opinions:

Triode vs Tetrode / Pentode - This depends on whay you want to hear.  Apples to apples Pentodes and Tetrodes typically give you more power.  As always, there are exceptions.  In my experience triodes sound "purer", with less grain and more of what Sam Tellig used to refer to as palpable presence.  BTW - if you like the sound of 300Bs, you should also listen to 2A3s or 45s, each one is more linear and extended than the typical 300B.

SE vs Parallel vs PP - There are times when be best circuit is the simplest circuit.  Again, SE is as simple as you can get.  Now the trick is, with only one output tube, you limit power and potentially bandwidth.  With parallel circuits you can increase power, but you have the potential for tube mis-match.  The audibility of this may be questionable (some people hear it, some don't.)  PP brings in the issue of phase splitters (which BTW don't have to be active devices, you can also use a transformer) and their issues.

OTL - Ralph Karsten has been making OTL amps for over 20 years.  They are reliable and rugged and sonically damned good.  The technology is sound (no pun intended.)  What Blair wrote makes little sense - Atma-sphere amps  are cyclotron amps and DO NOT have an output transformer; they also use triodes.  They aren't push pull, so I don't know where Blair gets his comments from.  BTW - you might want to investigate OTL, either Transcendent ot Atma-sphere, there are many member here that love what OTL does, and in fact, so does the press.

Hi Bob.
Thanks for the useful information, it's highly appreciated.
I am trying to learn how to cleanly respond to postings, but it's not easy because my computer it's not doing what I want. Sorry about that. I will find a different way to post my comments.
I wanted to insert my comment in red between Blair comments, but it did not worked.
It's not easy to choose between SE triode, push pull, OTL, etc...
Which is better ? That's what I am trying to find out.
Thanks and have a nice day.
Guy 13.

[Niteshade]

Continuing with your questions from the other day:

If it can be built, there will be a home for it. People will like it. You will find camps that swear the 300B is the best tube in the world. Same goes for any given tube or amplifier type.

There are those who enjoy OTL's, amps that produce under a watt and so on. They're not wrong! All that counts is that THEY are happy. You are going to be confused if you purchase based on what someone else says is good.

The best thing to do is ask me to make an amplifier that sounds a specific way. My judgment is very good.

As a manufacturer and designer, it is important to me to produce amps and preamps based on what people say they like. Here is a list of what is said:

I Like ______ (fill in)
A dark sounding system
A warm tone
A neutral tone
A bright, crisp tone
A subdued, syrupy tone
Heavy bass
Tight bass
Little bass
Easy listening
Loud listening

The list of what I get requests for goes on for miles.    Each and every one of these individuals believes their taste is the best and it is for them.

If someone tells me they want clean, clear power with a neutral tone and the amp has to be fast with good dimensionality, then I would suggest a pentode based amplifier. I can and do make amplifiers with pentodes that have these qualities.

People often forget that an amplifier's circuit and components are responsible for 98% of the sound quality. The tubes used do make an impression, but not nearly as much as most people believe. 

[Ericus Rex]

I am trying to learn how to cleanly respond to postings

The preview button helps alot.

[Guy 13]

The preview button helps alot.

Hi Ericus.
Thanks for the advice.
I always use the preview button, but this time I wanted to answer the comments of the sender with my comments in red between the sender’s different comments.
I’ve copied and pasted the sender’s text onto Microsoft Word but the background was grey and I could not make it white, in addition, I could not get my comments to show up in red when I copy and paste them to the post reply.

That’s not a big problem… But, can some one help me anyway ?
Thanks and have a nice day.
Guy 13.

[BobRex]

Guy,

Try this:

Press the quote button to respond to a post.  In the response window you will see some code as a header to the quote - "[quote......]", and some other code at the end -" [/quote]".  You can use this to bracket anything you want to be a quote, so that if you want to interject a comment inside of a quote you just go to the line where you want to comment and insert a "[/quote]".  The viewer will recognize the bracket as a command and will box and grey out the quoted material.  You can then add your comment on the next line.

When you are ready to quote more material, either copy and past the initial quote command (1st line of the post) or just type in "

" (drop the quote marks ", I just put them in to stop the interpretation of the bracketed command).  At the end of the quoted section just throw in another "

".

If this looks confusing, don't worry - it's easier to do than to explain it 

[BobRex]

Blair,

I'm just trying to make sure that Guy gets all points of view.  I understand where you are coming from and I'm happy that you recognize there are many paths to "sonic nirvanna."  Let's face it, it's tough for a newbie to quickly absorb what many of us have spent years at.

I've only ever seen one Futterman amp - back in the late '70s.  It came into our shop for repair (suprise!) and from what I remember it was a bear to work on.  I'm also not a big fan of the 300B - so far I haven't heard an amp using the tube that didn't sound depressed in the highs and a little too midrangey.

I am thinking of replacing my SE 2a3 amps, The Atma-sphere S30 is on the shortlist and I am intrigued by your SEP designs.  Don't be suprised if I call to set up a demo some day.

[Niteshade]

Bob,

That's fine! I am glad you jumped in.

"Which is better", "What should I do?" questions are tough. People will always stand by what they know works for them.

It's good to get people to 'think out of the box' so they know there are other ways of doing things. Class D amplifiers are a great example. They've come along way and filled many a niche.

[Guy 13]

Guy,
Try this:
Press the quote button to respond to a post.  In the response window you will see some code as a header to the quote - "".  You can use this to bracket anything you want to be a quote, so that if you want to interject a comment inside of a quote you just go to the line where you want to comment and insert a "".  The viewer will recognize the bracket as a command and will box and grey out the quoted material.  You can then add your comment on the next line.
" Lets see if it works ? Yes, it does work ! "
When you are ready to quote more material, either copy and past the initial quote command (1st line of the post) or just type in "".
If this looks confusing, don't worry - it's easier to do than to explain it 

I've followed your instructions step by step and it works.
Thanks a lot.
I have contacted Brian via a PM (Personnal message) and I am going with the SE-15wpc, I should have my amplifier some time in July it will be driving my GR V1 and I will post my listening impressions, no need to say that I am very anxious.
Again thanks and have a nice week.
Guy 13 in Vietnam.