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Jeffrey D. Medwin

Montana Directly Coupled 2A3 amps, versus Missouri KT88s, in SE/Pentode, Zero NFB

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11 minutes ago, babadono said:

Can't measure useful information be running a square wave through a supposedly linear audio power amplifier? Whaddayatalkinbout? JEESH!

We don't need no stinkin square waves!

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1 hour ago, CECAA850 said:

So you brought an amp that wouldn't play music correctly.  I'm at a loss.  If you can detect different ga wire in an amp, can notice one inch difference in wiring with your ears, can hear negative effects of tie wraps around caps, how can you not notice that your amp isn't reproducing all the music?

 

 

                       ******************     Its so nice to see you " not being critical " of what I straight-report.    ***************************

 

 

It can take from 6 to typically 12 months to fully-develop a new amplifier design.  It needs to be done on more than one system. 

 

This was just my very first test, on a system other than mine.  No designer gets it right on a first iteration.  Sol Marantz, for example,  had to trouble-shoot EVERY Marantz 10B , that Sid Smith designed,  and his factory built, not one was OK,  off the assembly line,  as built !!!  

 

You, being a buy - it - consumer, probably not an amp developer and / or builder,  and liking to find fault in me, whenever and where ever you can - seem to be oblivious to what happens in the real world !  Or, your distaste for me, will seem to over ride your own common sense.   

 

Your post was very mediocre in my opinion.  A poor reflection on you sir,  not the one you so-wanted to criticize and belittle !!  

 

All non - constructive posts are a reflection ...........and an embarassment,  of the person doing the posting !!

 

Jeffrey Medwin

 

 

 

 

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7 minutes ago, Jeffrey D. Medwin said:

Its so nice to see you " not being critical " of what I report.  

Not being critical just trying to understand how someone with a golden ear can proudly present an amp to a collection of audiophiles that won't play the entire spectrum of music.  Did you tell them it was defective and needed help straightening it out?  Did you not know it sounded bad ahead of the gathering?  I'm just curious. 

 

Notice how I had problems with what you posted not you personally.

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23 minutes ago, CECAA850 said:

Not being critical just trying to understand how someone with a golden ear can proudly present an amp to a collection of audiophiles that won't play the entire spectrum of music.  Did you tell them it was defective and needed help straightening it out?  Did you not know it sounded bad ahead of the gathering?  I'm just curious. 

 

Notice how I had problems with what you posted not you personally.

 

Yes, I told them it in advance, it was NOT fully developed, and I needed help in adjusting its playback in certain musical parts of the spectrum.

 

Yes, I certainly knew it was not completed.  I did as much as I could with MY sources, my parts on hand,  my budget, and with MY system. 

 

 I needed a better system and the best possible audio amps, and sources, to do comparisons.  Drove 3,500 miles to do so, my annual vacation.  In two over-night changes, I got things worked out, that would have taken me maybe six months to determine,  if at all, with the limitations I had.

 

 I use the top of the line BDP-09FD Pioneer Elite ( 30 pound )  Blu Ray player as a constant source.   Dennis uses the newer version of that, but he also runs the signal into a Berkeley Audio ALPHA DAC  with custom power supplies, and has LOVELY amps.   I was able to get things done in a far shorter order.   Also, Dennis is likely the most artistic and experienced person I know, in making subjective listening decisions of an amplifier, and transposing faults into strengths. 

 

Nothing was defective, ( your hurtful chosen word ) it is under development.

 

Jeffrey Medwin

 

 

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4 minutes ago, Jeffrey D. Medwin said:

Yes, I told them it was NOT fully developed, and I needed help in adjusting its playback in certain musical parts of the spectrum.

You left that out of your original post, you only said:

 

On first insertion of the KT88 amp, it truly " held its own " and showed promise,  and we were all favorably pleased - as an initial brief listen.  Dennis Fraker astutely pointed out the amp was missing music information, not playing it back at all, in a few areas, and I totally concurred.  He and I pulled the amp out, and Dennis made adjustments, changing mostly capacitor / power supply configurations.

 

It reads like Dennis noticed the flaws and you agreed with him.  Why would he astutely point something out that you've already told him?

 

 

 

 

Defective definition:

Imperfect in form or function

 

It seems to fit the definition.

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1 minute ago, CECAA850 said:

You left that out of your original post, you only said:

 

On first insertion of the KT88 amp, it truly " held its own " and showed promise,  and we were all favorably pleased - as an initial brief listen.  Dennis Fraker astutely pointed out the amp was missing music information, not playing it back at all, in a few areas, and I totally concurred.  He and I pulled the amp out, and Dennis made adjustments, changing mostly capacitor / power supply configurations.

 

It reads like Dennis noticed the flaws and you agreed with him.  Why would he astutely point something out that you've already told him?

 

 

 

 

Defective definition:

Imperfect in form or function

 

It seems to fit the definition.

 

 

I pointed it out in advance because I am astute !!  

 

Jeff Medwin

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3 minutes ago, Jeffrey D. Medwin said:

 

 

I pointed it out in advance because I am astute !!  

 

Jeff Medwin

 

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33 minutes ago, Jeffrey D. Medwin said:

I pointed it out in advance because I am astute !!  

So Dennis astutely pointed out something that you had already pointed out.  Got it.

  • Haha 1

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1 hour ago, CECAA850 said:

So Dennis astutely pointed out something that you had already pointed out.  Got it.

 

 

Now ya got it, he and I are both astute when it comes to this, but he is certainly the teacher, I am just the student.

 

He was able to recognize it on the first selection we played.  That was good !!  

 

Jeff Medwin

 

 

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15 minutes ago, Jeffrey D. Medwin said:

Now ya got it

I got it a long time ago.

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4 hours ago, Jeffrey D. Medwin said:

All non - constructive posts are a reflection ...........and an embarassment,  of the person doing the posting !!

 

Jeffrey Medwin

 

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20 hours ago, CECAA850 said:

I got it a long time ago.

I had it but I lost it.

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Jeff,  might this be done successfully (noting limitations) on a smaller scale with a 6BQ5?  FWIW I'd guess a tube driving a MOSFET (like the Bravo/Indeed headphone amps but with real voltage swing vs starved anode area swing) might (???) be better on the cheap than a poorly executed PP tube amp.  I dumped my EAR 509s in the 80's as felt they made Ivan Kozlovsky sound "old" ( he was 70 at the time of that recording - lol)  GREAT build - neat report.  

 

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5 hours ago, karlson3 said:

Jeff,  might this be done successfully (noting limitations) on a smaller scale with a 6BQ5?  FWIW I'd guess a tube driving a MOSFET (like the Bravo/Indeed headphone amps but with real voltage swing vs starved anode area swing) might (???) be better on the cheap than a poorly executed PP tube amp.  I dumped my EAR 509s in the 80's as felt they made Ivan Kozlovsky sound "old" ( he was 70 at the time of that recording - lol)  GREAT build - neat report.  

 

 

Yes, it actually could be done with a smaller tube.   But no one can build high performing tube amps "on the cheap".  These are two mutually exclusive concepts.

 

If I were to do a similar build, using a smaller tetrode or pentode Finals tube, I would not ever use a 6BQ5. 

 

I would consider using the military equivalent to a 6AQ5, however, which I prefer over any 6BQ5.  That would be a 6005, GE 5 - star.

 

I actually was thinking about a 6005 version, a few days ago.  

 

But, If I were to go to all the trouble to build such an amp ( its costly !!!  in parts and in building time ) I would just use the KT88 .  It is a GREAT tube choice.  Using the same design, the KT88's 42 Watt rated plate ( VS: a 10 Watt rated 6005's plate), simply makes most sense to me. 

 

Jeffrey Medwin

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Really looking forward to the subjective listening report by your friend and the testing you have lined up.

 

PWK would come in from the lab and frequently say something to the effect of "I got 10 things done today, 9 were total failures . . . ."

 

There are too many sucess stories about persistence,  hard work, trial and ERROR, etc. to repeat here.  The corollary to that is Albert's saying that repeating an experiment over and over and expecting different results is insanity.

 

Keep er moving.  

 

Looking forward to hearing what you find out.

 

Travis

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Thank God I'm happy with lesser grade equipment.

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If amp builders were writers there wouldn't be room in the trash bin for wire.

SSH

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37 minutes ago, avguytx said:

Thank God I'm happy with lesser grade equipment.

The assumption is that it is lesser.  I have a few amplifiers, from a couple of cheap class-D Q5 S.M.S.L amps to two Emotivas to a Neurochrome.  All have their sweet spots but I don't think any of them are bad.

 

I'm kind of glad I don't have the issue either.

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