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Jeffrey D. Medwin

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

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Hello All, 

 

Earlier, Maynard had asked me for a report on the trip to Montana with the new DC SE KT88 amp prototype.  So here it is.

 

There were four to five of us, traveling from as far away as Seattle and Richmond, VA., each of us very experienced with Serious Stereo  2A3 amplifiers, who became the "Montana listening panel."

 

First, we all listened to three different Serious Stereo 2A3 amps, using two different driver-tube types, three different output transformer types, and three different 2A3 tube types.

( The 2A3 tubes we heard were :  the ultra deluxe AVVT Mesh 2A3s, the EML Mesh 2A3s, and the JJ 2A3-40s.  )

 

None of our amplifier testing was done with electronic measurement devices, but rather, all judgments were made subjectively as a group - on music playback.  We all judged things such as human voices, full orchestra, highlighted solo instruments, and ordinary audience clapping between selections.  We used Dennis' top-of-the-line Pioneer Elite Blu-Ray Player as a music source, into his Berkeley Audio Design digital converter with special power supplies.  Music selections were primarily Celtic Thunder and the Eagles Farewell Tour, both nicely-recorded sources.

 

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.

 

Back into the system the KT88 DC amp went, the next day, and we had all liked the changes.  Dennis did one further round of adjustments, getting G2 to synch with the plate and G1, musically, in a precise way.  Playback on our two man music selections, became special to "me", in several ways:

 

a) When a 12 year old boy sang, we could finally sense his age, from his voice,  which was missing before .

 

b) When a group of five male singers sang in unison, we could separately hear the voice character, of each singer

 

c) When a solo acoustic guitar took the lead, we could sense each string's initial pick, the instantaneous pulsed dynamic rise, and the trail-off VERY precisely.

 

 

Never before, had I ever heard a) through c) - in combination,  from any single audio amp I have built and auditioned.  But I have certainly not heard them all !! 

 

Considering that the KT88 amp had zero break-in time, on the various film caps added, and the solder joints were fresh - no break - in, this was an encouraging result to initially hear. 

 

Two of Dennis' 2A3 amps did certain NICE things , musical things, that my prototype did not do, and that was GOOD for me to hear.  One Serious  Stereo 2A3 amp pair, I really liked, had perhaps $10,000 more in special parts, than all the others. It was" voluptuous sounding " to me, lovely to hear.   One other Serious Stereo amp prototype, more modestly constructed parts-wise, with a symmetrically made 7B4 driver tube - and a special  ( non E-I ) output transformer, played with the least distortion, and both Dennis and I liked that amp - a lot, for long term listening. 

 

Maynard, when I got the KT88 Prototype home from Montana, it played maybe 4 to 6 dB louder, with the same input voltage applied.  I can now easily HEAR the ranges that were missing, pre-trip-to-Montana, and there are TWO different changes we made in Montana, that may require a slight value or parts source ( Manufacturer WIMA to Mundorf Supreme Silver and Oils ) adjustment.  

 

Let me address more completely  " a), b) and c) " above, and what I THINK is happening.  Two things :

 

1) Some of the difference is between a 2A3 triode tube - and a KT88 beam power tube ( as Dennis and I are executing it ).  The KT88, a tube purposely designed for Audio, ....is a sleeper !!  

 

2) Some of the performance comes from six NEW design factors, employed  - together - uniquely in this prototype, to achieve a), b), and c) above.:

 

      ( 1 )   The B+ to the high gain Driver tube is uniquely DOUBLE shunt regulated,  ( double series regulation,  is precisely what Mr. Robert Fulton had me do in 1983 to my first design, " The Triode Music Amp ". )

 

      ( 2 )   The G2 B+ supply is resistively separated, and heavily shunt regulated ( 100 Watt chassis mount resistor ), and employs a Dennis Fraker Final Filter ( L/C ) right on the KT88's G2 tube socket pin.

 

      ( 3 )    G2's VDC was specially chosen by Dennis, to optimize G2 , to be triode-like, when purposely operated in a " Pentode " mode.

 

      ( 4 )   This amp uses multiple 5U4GB rectifiers, each acting as a single diode.  ( Ever hear a stock pair of McIntosh MC-60 mono tube amps fellas, or a McIntosh MI-200 with  Dennis Fraker mods ???  )  Two 5U4GBs very-beneficially halves the rectification's DCR.    It also ( .....two squared..... ) quadruples the Peak Instantaneous Current capability, of this lovely-sounding DIRECTLY heated rectifier tube.

 

      ( 5 )    I used single lead 8 AWG Mil Spec ( m22759/11 8 ) ground wiring  ( not done before ..... in any audio amp ).

 

      ( 6 )    I used separate filament transformers, for the driver tube and rectifier filaments, each properly phased to the main power transformer, and to each other.  ( fewer perturbations from the main B+  power transformer's high voltage winding is " seen " by the filaments ).  This translates directly as accurate ( audibly less disturbed ) playback of the original input signal.

      

 

Below is a photo of our group, listening in beautiful Livingston, Montana's Paradise Valley, the Gateway to Yellowstone National Park, last weekend.  All great audio listeners. 

 

Maynard, those " dire consequences " of me using zero negative feedback in my amp, never was a factor perceived .............by any of us.  Isn't that cool?  Dennis was correct, we two amp co-developers could get away with it !! 

 

Jeff Medwin

 

Below :  Dennis Fraker,  Jeff Medwin,  CoronaDope, and DrummerWill, front, Ash ( been running a Energy Company owned by Bill Gates - uses fancy Lowthers ).

 

1342668110_TubeWranglerDrLowMuCoronaDopeDrummerWillAshupfront.thumb.jpeg.d08dc238d25a011dce1d1e83e32ddd6a.jpeg

 

 

 

 

Jeff's Mentor, last three decades :  Dennis Fraker, lovely person !!

 

                             194105942_DennisFraker7-27-19.thumb.JPG.faa4f6ce9b6818425fcece159b7fdd38.JPG

 

 

Other interesting reading of this KT88 amp build is ( thankfully ) found here :  https://community.klipsch.com/index.php?/topic/182623-kt88-direct-coupled-design/

 

Have fun.

 

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Wow, I've never heard an 88 that I (personally) thought sounded as good as the AVVT 2A3s. I've had more than several 88s in my pCATS and do enjoy them very much. I've posted that the AVVTs are almost  like unicorns, now. My second pr was the last that Jacs had, and has never been used. Thanks for the post, Jeff. I suspect that this was a very red, red-letter day.

SSH

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On 8/3/2019 at 6:50 PM, ssh said:

Wow, I've never heard an 88 that I (personally) thought sounded as good as the AVVT 2A3s. I've had more than several 88s in my pCATS and do enjoy them very much. I've posted that the AVVTs are almost  like unicorns, now. My second pr was the last that Jacs had, and has never been used. Thanks for the post, Jeff. I suspect that this was a very red, red-letter day.

SSH

 

Hi SSH:

 

I do not know what pCATS are.

 

Likely my amp is the first KT88 Directly Coupled  SE Pentode amp ever made in audio's history.  Especially with zero negative feedback.

 

It has a separate G2 supply ssh, which everyone knows is the best way to run a Beam Power tube ( KT88 ) or a Pentode. 

 

Most KT88s  people hear run G2 either ultra linear or triode connected, ......which Dennis and I wanted to avoid.  Most KT88 amps will use negative feedback, which Dennis and I wanted to avoid........ like the plague. 

 

Drummerwill ( part of the Montana listening panel )  was really impressed, and he has posted on Audio Asylum. 

 

The KT88 amp we all heard in Montana had brand NEW film caps added to it while in Montana, VS the three new pairs of monoblock Serious Stereo 2A3 amps that were fully broken-in. 

 

In the last two days, since I am home, I have put some hours on the Montana-adjusted KT88 amp, and, good news, the film caps are starting to break in.   

 

Amp sounds subjectively ....easily over 10% better to me, than in Montana right after the parts adjustments.    But its a YO-YO...... 'till these newly added caps do their final settling-in !!!   Two weeks usually.

 

I want you to know ssh,  I personally believe it is NOT purely a matter of just one tube VS another.  I took the time  ( Points 1-6 above, in my introduction ) to explain all that was different, circuit-wise.  

 

I firmly believe all those six circuit changes are necessary, highly desirable.  Some of the six may ALSO be applied to a 2A3 amp, of high caliber ( read latest Serious Stereo 2A3 amps - my favorite ).  

 

I use the more recent ( improved ) EH KT88s, less than $90 a matched pair VS about $3,500 a pair for those AVVTs you are hoarding. 

 

Cool, eh ??  Audio can be fun.  Regards.

 

Jeff Medwin

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Do you think that different brands of Kt-88 tubes would sound different in your new amp? I'm curious because I have an ultralinear amp and a single ended amp that take KT-88's, and some tubes sound better to me than others.

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6 hours ago, kevinmi said:

Do you think that different brands of Kt-88 tubes would sound different in your new amp? I'm curious because I have an ultralinear amp and a single ended amp that take KT-88's, and some tubes sound better to me than others.

 

Hi Kevinmi :

 

Yes, different tubes do sound different - in any circuit.   That is typically the case.

 

But " tube rolling " to me -  is one of the most minor ways of getting musical performance differences ( sometimes improvements ) from an audio amp. 

 

I'd suggest any brand of KT88 will respond similarly, and positively, to the six things outlined in my initial post, and also - to a L.S.E.S. power supply powering / filtering the Final stage's B+. 

 

Regards,

 

Jeff Medwin

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Jeff, now that the amp is back home, can you please post a 3kHz to 5 kHz square wave at around 250 millivolts across an 8 ohm resistor?  While I agree that subjective impressions are always extremely important, I find it valuable to try to correlate what we hear with objective measurements.  Doing that allows for other amps to be developed which offer similar characteristics.  

 

Also, if you have time, can you measure the output impedance as well?  That too may shed some light on why the synergy between the amp and your/Dennis' speakers is so pleasing to you.

 

Thanks---

 

Maynard

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7 hours ago, tube fanatic said:

Jeff, now that the amp is back home, can you please post a 3kHz to 5 kHz square wave at around 250 millivolts into an 8 ohm resistor?  While I agree that subjective impressions are always extremely important, I find it valuable to try to correlate what we hear with objective measurements.  Doing that allows for other amps to be developed which offer similar characteristics.  

 

Also, if you have time, can you measure the output impedance as well?  That too may shed some light on why the synergy between the amp and your/Dennis' speakers is so pleasing to you.

 

Thanks---

 

Maynard

 

Respectfully ......Nope. 

 

I don't own a good square wave generator.   I do own a TEK 565B scope Maynard, and dual probes.

 

But if you want to come in with equipment to measure it, you are welcome any time Maynard.   

 

The tests you mention will not reflect what the tube as implemented, and the amp, can do !!!   You can not develop amps from a square wave trace.

 

 

For example :

 

Will the square wave show us the age of the 12 year old boy, in his voice playback, or

 

will the square wave show the dynamic envelope and nuance of each picked guitar string?? 

 

...... or .......how five guys, singing in unison, can be individually heard voice-wise??

 

 

 

I feel its sort of like measuring a new Ferrari with a retractable tape measure, from ACE Hardware, but one never takes the vehicle out for a drive on the highway.

 

 

( Maynard, you can send me a generator, postage free, and I will measure it and save you a trip.  You would have to teach me how to measure impedance. 

or ..... send a trustworthy  Kansas City area technician over, and they can measure it . )

 

Next someone will ask " How many Watts does it put out clean, without distorting a sine wave ? " 

 

I only need to know one thing ...how well does it play back music on my load ?

 

What if it measures poorly yet sounds superb , as in world-class ???  

 

I hope I have not offended anyone, but we two guys approach amplifier designing differently.

 

Jeff

 

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3 hours ago, Jeffrey D. Medwin said:

I hope I have not offended anyone, but we two guys approach amplifier designing differently.

Jeff,

 

I can appreciate this.  I think there is every reason to believe that what you stated should NOT be offensive.  It's simply a different approach.  Your language reminds me very much of Susumu Sakuma, the Japanese amplifier designer with whom I'm sure you are familiar.  Where voicing of components is done through listening alone, and where objective measurements do not venture much further than the electrically 'safe' application of active and passive parts.  To me, it is very much of an art form, where intuition and long experience are the sources of inspiration for new designs.  And he wasn't afraid to break long-established rules of commonly understood, accepted, and practiced tube audio electronics.  In tuning or voicing components to a specific kind of loudspeaker -- the Lowther PM6A - he started using interstage coupling (just as you have found direct-coupling) to be the most appropriate way of achieving a desired sound.

 

For those unfamiliar with this now late Japanese designer, follow the link to some neat information and some really nice-looking amps!

 

http://www10.big.or.jp/~dh/amp/index.html

 

And of course Maynard's effort here, though different, is most definitely and arguably every bit as valid - for him, and many others who follow a similar path.  It's why components in audio magazines like Stereophile are also put through rigorous testing measurement.  

 

 

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On 8/5/2019 at 1:53 PM, erik2A3 said:

Jeff,

 

I can appreciate this.  I think there is every reason to believe that what you stated should NOT be offensive.  It's simply a different approach.  Your language reminds me very much of Susumu Sakuma, the Japanese amplifier designer with whom I'm sure you are familiar.  Where voicing of components is done through listening alone, and where objective measurements do not venture much further than the electrically 'safe' application of active and passive parts.  To me, it is very much of an art form, where intuition and long experience are the sources of inspiration for new designs.  And he wasn't afraid to break long-established rules of commonly understood, accepted, and practiced tube audio electronics.  In tuning or voicing components to a specific kind of loudspeaker -- the Lowther PM6A - he started using interstage coupling (just as you have found direct-coupling) to be the most appropriate way of achieving a desired sound.

 

For those unfamiliar with this now late Japanese designer, follow the link to some neat information and some really nice-looking amps!

 

http://www10.big.or.jp/~dh/amp/index.html

 

And of course Maynard's effort here, though different, is most definitely and arguably every bit as valid - for him, and many others who follow a similar path.  It's why components in audio magazines like Stereophile are also put through rigorous testing measurement.  

 

 

 

 

Thanks Erik, 

 

You are very kind.  I have several spare low DCR ( 8 Ohm Hammond ) chokes for your Moth project BTW. 

 

Interesting twist here !!  I just found out  - some of the initial listening conclusions of what we all heard, were NOT fully understood by those of us ( Drummerwill and myself ) who opened our mouths and reported . 

 

Without going into any discussion, I would ask all folks to take our two sonic Forum reports with a grain of salt.  PLEASE !! 

 

I have been undeniably shown how, inadvertently,  I have misled readers here, which is the very last thing I would seek to do !!. 

 

There was no ill intent, but ten minutes ago, I came to understand what was going on in the listening sessions.

 

Yes, I consider Maynard to be one of the best people I have met in audio, and in life.  Its a shame we two aren't now still living 60 miles apart, as we were many decades ago.

 

Jeffrey

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On 8/5/2019 at 10:43 AM, Jeffrey D. Medwin said:

 

 

For example :

 

Will the square wave show us the age of the 12 year old boy, in his voice playback, or

 

will the square wave show the dynamic envelope and nuance of each picked guitar string?? 

 

...... or .......how five guys, singing in unison, can be individually heard voice-wise??

 

 

Jeff

 

 

Jeff, as shown below, you are missing out on a truly amazing listening experience!  It's how I listen frequently!!! 😀

 

Maynard

'scope pic.JPG

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Maynard,

 

Early next week I will be lending-out my new KT88 SE DC amp for three weeks  to my trusted friend in Kansas City, who owns and lives in a 1911 K.C. Firehouse ( horse drawn equipment ) for him to listen to.

 

He runs either ALTEC A2s or A4s. .........you know, multiple 515B woofers and a 288 top-end driver.   

 

                        1206567113_A2andA4.JPG.dfb6e6f25858a381b5cefe65e2579a38.JPG

 

 

He works for a Professional Sound Equipment company, that does Commercial Installations, all over the USA - mostly Mid-West.  

 

I would think my friend will either own, or have access at his shop, to measuring equipment, so we can all see what a square wave looks like, etc.  I will inquire, and post results of this DC SE KT88 prototype 

 

I mentored him, about 25 years ago, to build his first DIY 2A3 SE amp, and we have been on great terms, ever since !!  Cool guy, cool HUGE "home" and cool audio system in it.

 

Stay tuned, a few weeks away.  Thanks for your input Maynard.

 

Jeff Medwin

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Added heatsinks today , as a final step for long-term reliability. 

 

Need to clean up Thermal Grease neatly, but new KT88 amp is done today.

 

 

     2067792593_SNIP35.JPG.d93bd48ad2dd41001c36a0db0a77fa61.JPG

 

Weighs a hefty 50 pounds.  Observe how the 120 VAC PowerTransformer and rectifiers fields are opposite and as FAR away as possible, from the amp's lowest-level audio signals,  ie: the RCA Jacks and the Driver tubes !!  This is advantageous, performance-wise - simply better in lay-out / design.

 

 

    1591763727_SNIP28.JPG.4ae0ddcd650d507d62c00726c4923973.JPG

 

 

      Gee, I will have to paint the power transformer's laminations black now !!  Will do that after I clean up the two heatsinks' thermal grease residues.

 

 

    SNIP 33.jpg

 

 

                                                                         I wish people could hear how this amp plays back on a speaker .   

 

 

                                               SNIP 19.JPG

 

Six brass washers at each bottom cover attachment point elevate bottom cover.  There are three different Outside Diameter brass washers used, forming a brass Pyramid shape, as part of the amp's Isolation Platform ( this copies a Dennis Fraker  / Serious Stereo 2A3 amp / 1989 invention ).   Highly Audible.

 

                                                   Jeffrey Medwin

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After the Livingston, Montana amplifier testing trip/vacation a few weeks ago, at my audio mentor's shop, TEST TWO of the new KT88 amp is happening over the next month, starting Monday evening, right in Kansas City.  

 

I loaded my new KT88 Directly Coupled Pentode amp into my old friend Randy's SUV on Friday afternoon, and told him to take about a month to evaluate the unit.  He was the fellow owning / living in the 1911 horse-drawn Kansas City Firehouse station.  He was running a Yamomoto A-08 Type 45 amp, and had tremendously huge ALTEC A2 and / or A4 speakers, in his cavernous listening area.

 

Fantastic news, unknown to me, Randy has upgraded both his speakers and amplifier since I last visited him, well over a year ago.   

 

For speakers, he has ALTEC 416B woofers reconed and remagnetized..  He constructed a DIY SIXTEEN CUBIC FOOT MLTL enclosure for them.  Its a two way.  On top of each enclosure is a ALTEC 32 ( 90 degree bent ) high frequency horn, with an 802D High Frequency compression driver doing top-end duty.  A KISS, large two way MLTL. 

 

When he sends me external and internal pictures of his custom build, I will show you all what they look like.  Its a very cool DIY build.  The 15 inch is obviously, directly radiating into the listening space. 

 

What really pleases me is he upgraded his " pretty " Yamomoto A-08 Type 45 amp ( which my own 2015 Type 45 DC amp " destroyed  " on a A-B , three years ago ) for a pair of 20 Watt rated monoblocks.  A " Thoress 845 amp ", made in Germany by Reinhard Thoress, of Aachen.   It uses three tubes, but its only a two - stage amp, which I LIKE, .....always better than a three stage amp.  Zero negative feedback , just like my amp, ....which I like, demand. Rated 20 Watts.  I was told these 845 monoblocks retail for $14,000 a pair, so it will be a great choice for Randy to compare, to the new KT88 stereo amp prototype .

 

The Thoress website is here :

 

http://www.thoeress.com/en/   Click on 845 amp, their top of the line offering.

 

Here is what one monoblock looks like :

 

                1541455409_PhotoThornessAMPN845.thumb.JPG.0093ddb03180cc4f82915555fd4daef8.JPG

 

                                                                                                                and the internals look like so :

 

               2040105494_PhotoThornessAMP845INTERNAL.thumb.JPG.0ce8976edb8839ce304897185ed4e185.JPG

 

 

My friend Randy is employed in the professional audio Installation business, for commercial enterprises / venues,  and he has someone who is excellent, who will measure my amp, on square waves, etc etc, as per Maynard's request - in the early part of this thread.  We will take o-scope pictures. 

 

Maynard thinks he can tell an amp's " goodness "  and sonics from the square waves, and he hopes I will learn something.  I think Randy should have BOTH amps nicely measured, post them, and most important of ALL, report to us on how each plays MUSIC, comparing one to the other,.   Randy will hopefully tell us which amp he likes best, and by what magnitude, and ways,  is one superior to the other !!!  .

 

Personally, I just want to know what sounds best to him, on music playback, over a month's time. 

 

What I think would be GREAT FUN, is to post the square wave shots of both amps ( Thoress 845 and my new KT88 Pentode ) up here without designating -  which is which  - and have Maynard comment here to us, on what he likes best, and how Maynard thinks they will sound..

 

Then, afterward, we need to divulge square wave identities, and compare the data, to what Randy will write up and hopefully share with us, during the month he subjectively performs his own evaluations on music playback.  Fantastic !!  

 

Maynard, is that asking too much of you ??  Hope not.  It will be FUN , and instructive - to see that transpire.  Do you feel I have " set you up ?? "  If so, feel free to beg - off sir.  In any case, we WILL SEE the KT88's square waves, and other measurements up here in several weeks, for both of us to learn from, Maynard.

 

It is also possible,  I may be able to find a Kansas City Klipsch owner, and  possibly do yet another KT88 amplifier A-B there, depending on speakers and gear types he owns.  The truth, will be known. It will set us free !!

 

Jeffrey Medwin

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On 8/5/2019 at 8:23 PM, Jeffrey D. Medwin said:

Interesting twist here !!  I just found out  - some of the initial listening conclusions of what we all heard, were NOT fully understood by those of us ( Drummerwill and myself ) who opened our mouths and reported . 

 

Without going into any discussion, I would ask all folks to take our two sonic Forum reports with a grain of salt.  PLEASE !! 

 

I have been undeniably shown how, inadvertently,  I have misled readers here, which is the very last thing I would seek to do !!. 

 

There was no ill intent, but ten minutes ago, I came to understand what was going on in the listening sessions.

Jeffrey

 

A few days ago you advised everybody to take your reports about amplifier performance with a grain of salt, because you hadn't understood what was going on.  Do you have any updates on this?

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8 hours ago, Backfire said:

 

A few days ago you advised everybody to take your reports about amplifier performance with a grain of salt, because you hadn't understood what was going on.  Do you have any updates on this?

 

Your question is reasonable IMHO.

 

That warning occurred thirteen days ago. .  While we were all in Montana, we had a single technical problem, that partially-obscured what the group heard.  The experienced listeners in the group were able to hear through the difficulty, and have a good idea as to performance, but I wanted to be conservative in my public representation, so I authored that warning Backfire.

 

Since then, the amp has had two weeks of break-in playing time, to form the many many bypass capacitors inside it.   

 

The current test will be out of my hands.  Longer term ( I will let Randy have the KT88 amp a month ) Randy will compare it against the $14.000 a pair Thoress monoblocks, and hopefully, he will provide me with a written subjective report, he authors.  I'll post it here. (  I actually THINK I already know what the comparison results will be. )  But I'd rather have him report his results, so I am "Mum" at this juncture as to what I think he will hear.

 

What is now VERY interesting to me is having Randy allow his lab-experienced friend to possibly measure BOTH zero feedback amps, take Square Wave O-Scope photos, ( as per Maynard's suggestions ) and we cam find out IF the subjective and measured results - synchronize with each other.  That will be COOL !!   We will all learn something !!!!!!!!!

 

One final thought I had, since this is a Klipsch Forum  :  if the KT88 amp does not embarrass itself  ( compared to the $14K 845 Thoress monoblocks ), I will try to have a Kansas City area Klipsch owner evaluate this new KT88 design in his system, and have that person independently post a listening report.  

 

Jeffrey Medwin

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Randy's New Testing Components:

 

Here are the photos of his DIY SIXTEEN cubic foot enclosure for a rebuilt ALTEC 416 15 inch Woofer.  And one photo he took of one channel of his new Thoress mono amps.  He will be evaluating the new KT88 amp of mine with both these components, in his 1911-built Kansas City horse-drawn Firehouse station.. 

 

Randy has a friend who will do tube amp measurements Maynard suggested.  We will all learn from that, I hope.

 

107027591_16CubicFootMLTL416.JPG.041a4846d4aa552ef659d176c34b01ef.JPG

 

 

Can you spot the partially-covered-by-blankets huge ALTEC A2 or A4 speaker system, behind the new smaller 16 cubic foot MLTLs?? 

 

New 2-way MLTL speakers, below, use ALTEC 416 woofers,,  Altec 802  compression drivers, on Altec 32 bent horns,  with a special crossover.

 

2017007238_New16feet416MLTL3.JPG.4aab6221db4dec0d54381ab9a1e1d972.JPG

 

 

 

499402206_MLTL2.jpg.39a0ac36039f3a0c5a7c2be1850c92a8.jpg

 

 

Sure is a amplifier chassis pretty color.  How will it compare to the new KT88 stereo amp prototype, THAT is the question !!!  

 

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On 8/18/2019 at 2:22 PM, Jeffrey D. Medwin said:

While we were all in Montana, we had a single technical problem, that partially-obscured what the group heard.

 

And what was it? Why the vague details?

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Since then, the amp has had two weeks of break-in playing time, to form the many many bypass capacitors inside it.   


Since they’re all in parallel, you’d think it’d be done by now.
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On 8/3/2019 at 4:07 PM, Jeffrey D. Medwin said:

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. 

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?

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

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