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Shakeydeal

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1 hour ago, mikebse2a3 said:

I find the obsession some people have with “neat pleasing to the eye wiring style” to be misguided and often sacrificing the benefits of 3 dimensional wiring of good point to point designs that can look messy to an untrained eye.  
 

miketn

Here are a few examples of what my products look like "under the hood"...... Hmm....... can't shrink them down far enough to get three of them on here.

 

Instead, I'll post a link to the gallery on the website for these pics.

 

https://www.toolshedamps.com/inprocessconstruction

 

The wiring methodology is my own, it does not emulate anyone's style. I'll be adding construction pics as time allows to this gallery.

 

And, yes, nothing is as it is accidentally. All of these choices have been deliberate. Everything has been carefully selected based on the tonal colors it adds to the finished piece. These selections cannot be quantified by math alone........... after all, a 220R/1/2W resistor is a 220R/1/2W resistor isn't it? Whether it's carbon film, metal film, carbon comp, thin-film, or tantalum doesn't matter........... or does it? Even if they measure the same? Hmm............? This then is a rhetorical question, of course they all sound different, despite measuring the same. The human ear doesn't lie, and it is IN FACT the most important development tool we have. Because once we've crossed our "T's" and dotted our "I's", they are the tool that can mean the difference between a good amplifier, and something truly magical. :)

 

Cheers!

 

Matt.

 

 

 

 

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2 hours ago, mikebse2a3 said:

I find the obsession some people have with “neat pleasing to the eye wiring style” to be misguided and often sacrificing the benefits of 3 dimensional wiring of good point to point designs that can look messy to an untrained eye.  

LOL, I'll let that slide, as that wasn't what I meant.

 

Matt, they are gorgeous amps, and I am sure, as reported, sound wonderful.

 

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32 minutes ago, ToolShedAmps said:

These selections cannot be quantified by math alone

 

Yes they most certainly can be.

 

Mainly look at two data points given in the spec sheets. One is temperature coefficient and the other is voltage coefficient. In theory a resistor would be an exact resistance at all frequencies, temperatures, and potential differences across it's terminals. When drawn on a graph that perfect single resistance would end up being a straight line, or called linear.

 

In the real world resistors are not perfectly linear due to their coefficients. Let's look at voltage coefficients in an application. If you were to take a resistor with a very high voltage coefficient, it would measure at one resistance with say 5v across it, typically close to it's rated value but when you get up to say 50v across it the resistance value has changed. On a graph this no longer makes a straight line, it has become non-linear. Non-linearity causes even harmonic distortion. So resistors with a high voltage coefficient will have more distortion where there is more signal swing across it. Like plate loads, especially plates that swing large voltage swings like phase inverters or driver stage for a DHT amplifier.

 

Temperature coefficient is similar in that the resistors change their resistance value depending on it's temperature. 

 

If you have a keen mind you will notice that for any given resistor type, carbon, film etc... they all will have lower voltage and temperature coefficients the larger their power rating is. A 1 watt resistor will have much lower voltage and temp coefficients compared to a 1/4 watt resistor. So it's smart to pick critical resistors and oversize them for better linearity.

 

Nothing in this is magic, it's all been easily explained a long time ago.

 

If you want low distortion in a single stage DHT amp driver circuit then just lose the resistor load on the plate like all modern amplifiers and use a better load. When you look inside modern SS gear almost everything is loaded with a current source which gives low DC losses but very high AC loading leading to much lower distortion compared to a resistor load. I personally prefer a gyrator load on the plate. So although it's great you are choosing resistors that have low distortion it's still light years behind a more linear load for the driver stage of the DHT amps. I am certain you will see a pretty drastic drop in distortion changing from a resistor plate load in your amps to anything more linear.

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Years ago I was experimenting with a 417A input tube interstage coupled to a 2A3 similar to the image in this thread.

 

My main goal was to see what "all the rage" was concerning this input tube (417A) being transformer coupled to a 2A3/300B. I don't remember my circuit values, but they were different from the ones in the circuit uploaded. I tried a lot of different operating points for both the 417A & 2A3 and was not satisfied (measurement wise) with any of them. 

 

Overall, changing the operating points only changed the sound slightly. Nominal distortion was >1% @ 1 Watt, 8 Ohm. This in my opinion is too high, but there did seem to be A LOT OF MAGIC going on in the sound. I bit too much magic for me. 

 

The magic in this case was 2nd harmonic distortion and gobs of it. As I said, I am going from memory, and I did not save any circuit notes or graphs from my AP. 

 

I  may need to mock it up again and post the AP results. 

45-2A3-TransDrive-v4a.png

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Good God…. You are missing the point. This is musical. I’ve tried everything from gyrator, J-Fet CCS, tube CCS, inductor, you name it to load my voltage amplifier stage/s…. this sounds BETTER to my ears. And they are in fact, what my customers rely upon.

 

Please don’t turn this thread into some sort of inane engineering pissing match. I have no idea what you think you need to prove to anyone. Armchair braggadocio and looking down ones own snoot at the effort of others is seldom attractive. 

 

It’s my amplifier I will build it as I see fit. My customers truly enjoy the music that it makes. 107…. and counting.

 

And really, that’s all that matters.

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1 minute ago, ToolShedAmps said:

Good God…. You are missing the point. This is musical. I’ve tried everything from gyrator, J-Fet CCS, tube CCS, inductor, you name it to load my voltage amplifier stage/s…. this sounds BETTER to my ears. And they are in fact, what my customers rely upon.

 

Please don’t turn this thread into some sort of inane engineering pissing match. I have no idea what you think you need to prove to anyone. Armchair braggadocio and looking down ones own snoot at the effort of others is seldom attractive. 

 

It’s my amplifier I will build it as I see fit. My customers truly enjoy the music that it makes. 107…. and counting.

 

And really, that’s all that matters.

 

You made a pretty bold statement that resistors should be the same but they aren't and that math doesn't explain why, but it does and that was the only point I was making.

 

So your ears prefer distortion, that's fine nobody says you have to like anything in particular.

 

You are selling amps that's great!! I am certain the looks of them is what sets them apart and sells them. The circuits themselves are pretty standard two stage zero feedback designs that have been built a million times before your amps were even available. For people that prefer a cleaner sound they typically use a more linear load for the driver but that's not a golden rule, if you like distortion stay with the resistor that's what great about being the engineer, you make the choices. We were triode strapping high gm pentodes as DHT drivers 20-30 years ago, it's nothing new. Before that you typically saw cascading 6SN7's. Your chassis are novel which is what has caused a stir which is great don't get me wrong. You are very talented at that.

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Of course measurements have real value “when implemented and interpreted in the proper context and with their limitations recognized..!!!“ but ultimately we are designing not for a meter/test but for the human experience and the latter is the ultimate goal and the meters/tests are just tools that must be used wisely and within their limitations.  

 

Heyser who was a pioneer in measuring Audio, Acoustics and Sound Reproduction wisely warned the audio engineers of what was the intended results of their labor and the best engineers understand this fact I’m sure. By the same token the listening experience is also dependent in part by experience and training when it comes to making valid judgements when comparing sound reproduction from our Equipment/Room..!!!

 

Einstein:  "Not everything that can be counted counts, and not everything that counts can be counted"

 

Richard C. Heyser:  “Perhaps more than any other discipline, audio engineering involves not only purely objective characterization but also subjective interpretations. It is the listening experience, that personal and most private sensation, which is the intended result of our labors in audio engineering. No technical measurement, however glorified with mathematics, can escape that fact.”

 

 

miketn 

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35 minutes ago, captainbeefheart said:

So your ears prefer distortion, that's fine nobody says you have to like anything in particular.

 

Could it be that the distortion isn’t what someone likes but the lack of some unmeasured distortion that the ear/brain perceives but not revealed by the test you chose to measure with…?

 

miketn

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2 minutes ago, mikebse2a3 said:

Of course measurements have real value “when implemented and interpreted in the proper context and with their limitations recognized..!!!“ but ultimately we are designing not for a meter/test but for the human experience and the latter is the ultimate goal and the meters/tests are just tools that must be used wisely and within their limitations.  

 

Heyser who was a pioneer in measuring Audio, Acoustics and Sound Reproduction wisely warned the audio engineers of what was the intended results of their labor and the best engineers understand this fact I’m sure. By the same token the listening experience is also dependent in part by experience and training when it comes to making valid judgements when comparing sound reproduction from our Equipment/Room..!!!

 

 

 

Einstein:  "Not everything that can be counted counts, and not everything that counts can be counted"

 

Richard C. Heyser:  “Perhaps more than any other discipline, audio engineering involves not only purely objective characterization but also subjective interpretations. It is the listening experience, that personal and most private sensation, which is the intended result of our labors in audio engineering. No technical measurement, however glorified with mathematics, can escape that fact.”

 

 

miketn 

 

I completely agree. I am not one that gets hung up on getting vanishingly low distortion as I know it's not the end all determining factor in sound quality. Some wouldn't entertain the idea of 1% THD but that's about what I find to be where it becomes perceivable to the average person. Some people can even hear if the second harmonic is in or out of phase with the fundamental below 1%, so it has it's effects.

 

Someone that has 105db/1watt speakers may never get above 1 watt with their amplifier and so 5% THD at 7 watts never comes into play for them while others may prefer very complex music and require more power, if the amplifier cannot cleanly deliver it the sound becomes muddied. People have different requirements which is why I ultimately say that to know if these low power, high distortion amplifiers will work for them is to actually audition them. It might meet the needs of some but not others, that's why there are so many different amplifiers out there.

 

I have no intention of having an amplifier company, I just enjoy making amplifiers for myself or others. I get great joy bringing people the sound they want without spending huge money. Which is why I try and not push one particular type of amplifier, designs have tradeoffs and when someone is interested in having an amplifier made I try and gather as much information as possible to make an amplifier that will suit their needs best. A low powered SET amp is not for everyone.

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20 minutes ago, mikebse2a3 said:

Could it be that the distortion isn’t what someone likes but the lack of some unmeasured distortion that the ear/brain perceives but not revealed by the test you chose to measure with…?

 

Distortion is a change of the waveform between input and output, any difference will be measurable and quantifiable.

 

Not all distortion is equal, you can view them to music theory as a parallel. The second harmonic is a musical octave, the third harmonic a 12th, etc..  These are known as musical intervals and a form of harmony.

 

If you want to break things down to what is natural, sound waves in the air to the ear is expressed with equations in fluid dynamics. In laymen terms the high pressure peaks will travel faster than the low energy troughs which leads to a non-linear transfer and subsequent even harmonics. So one could say even harmonics are more natural vs odd harmonics. This is a very well known concept and why SET amps sound nice due to the even harmonics. In guitar distortion world some prefer linear distortion which produces a more aggressive odd harmonic content. Square waves produce odd harmonics for example.

 

Typically you don't want distortion but low level even harmonics are going to be much more benign and natural compared to odd harmonics.

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21 minutes ago, captainbeefheart said:

A low powered SET amp is not for everyone.

I go from one extreme to the other. My tube amps satisfy most of my needs, but sometimes I've got to play my music louder, but I still want the"magic" sound that a tube amp gives me. That's when I switch to one of my SS amps. 

 

One of my recent favorites is a Phase Linear 700B chassis that was stripped and reconfigured for full complimentary outputs and a completely new discrete driver board (designed by me of course). I have the PCB ready to go, I just need to send it off to a PCB house. 

 

The proto-type driver board is in it now, is a highly modified factory board for proof of concept. 

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3 minutes ago, captainbeefheart said:

Distortion is a change of the waveform between input and output, any difference will be measurable and quantifiable.

 

The problem is that the typical standard type distortion you are referencing are made with waveforms that are basic and simple but in reality they don’t even begin to put the amplifier under the conditions that we are requiring it to perform with (ie: complex musical waveforms which are transient in nature as well and unlike your basic distortion test typically sited).

 

Do you believe that a typical harmonic or intermodulation distortion test really represents a complex musical waveform which is really what an amplifier has to pass..?

 

miketn

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For anyone interested sit down at a piano and play these musical intervals that relate to harmonic distortion. You will be able to hear the difference in what these different harmonies sound like which directly relates to how harmonious the type of distortion is.

 

So it's not just total harmonic distortion, but what TYPE of distortion it is made up as.

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2 minutes ago, mikebse2a3 said:

Do you believe that a typical harmonic or intermodulation distortion test really represents a complex musical waveform which is really what an amplifier has to pass..?

 

A good engineer shouldn't just test using a sine wave, that's just one standardized test procedure.

 

You can use any test you feel fit. Multi-burst tones, square wave tests, IMD, TIM, etc.......... The amp should reproduce any waveform accurately in the audio band so as long as you know what type of test will show what you are trying to view. Sine waves are not the whole picture which is well known which is why we have a multitude of tests.

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