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jimjimbo

Huge 833A tubes

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To be accurate, and not to overstate what is being heard with a KT88 DC amp, please note my observations are from a several day listening session, in mid 2019, using a TOP NOTCH system for evaluation.  All four of us who were present, individually heard this !! 

 

The most recent EH KT88 - 2A3 amp observations are those INITIAL ones of my audio mentor, Dennis Fraker.  He's got both his newest ( built 2020 ) pairs of monoblock amps, ( 2A3 and KT88 ) at his home in Montana, to listen to. 

 

Dennis' positive observation about a EH KT88 was his INITIAL listening reaction.  Short term listening.  This, my friends, can change !! 

 

He will go back and forth between the two sets of monoblocks, and make additional determinations, which he is capable of doing. 

 

I know for a fact, that as of today, 6-20-2020, he feels his KT88 monoblocks are not yet finished.  These now use a Russian 6E6P, triode wired,  as the driver, at about 9-10 mA. into the grid of the Beam Tetrode.   Regarding 2A3s as Finals he has been building 2A3 DC amps since 1989, and I think he feels that the latest Generation 4 / 2020 2A3 amps are a " go ".   This Beam Tetrode amp is his first pair built,  ( other than the stereo 2019 amp of mine, wherein he generally guided my build. ) 

 

So, it would be fair to say, that he and I are in the learning / discovery stage of audio experimenting.  We are not both fully decided, what will be the most fun to use, long term.

 

A cool take-away is that my own 2019 KT88 build applied several new build techniques, ( outlined in prior Klipsch Forum posts ) which Dennis has improved-further-upon in 2020, and these can be applied to any SE DC amplifier circuit, 2A3 or KT88. 

 

Solid progress is being made, in performance, musically-listening-wise.  Exciting times !! 

 

I should point out, pertaining to this thread's 833A tubes, if your highly efficient speakers only need a good Watt or two to adequately drive it, why build a complex / multi-stage amp using a large transmitting triode for the Finals tube, that looks cool, but requires, as someone posted, 20 Watts to drive the tube??

 

Jeff Medwin

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Very exciting indeed!  However, the real takeaway here is that you and Dennis share listening taste in terms of the amp’s harmonic characteristics and its relationship to the speakers with which it is tested.  One cannot assume that those characteristics will be universally appreciated just as some audiophiles find all tube amps to be unacceptable, and as we find SS amps to be unacceptable.  One other question is whether it is necessary to build an amp as complex as yours to achieve a result which is equally pleasing.  That, of course, is a question without an answer.  A certainty is that there is no amp in existence (mine included) which will interface with all speakers and listener preferences.

 

 

Maynard

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Maynard,

 

There is an answer for me. 

 

I can assure you, from my own DIY building,  a certain amount of complexity and cost is required, to get the best possible music performance, from a tube amp that will be satisfactory - to me.   

 

I often use capacitor bundles of 4 to 7 different types and values of film caps, ( wherever all others will use just one cap ), and this makes the circuit " look" busy.  The basic circuits themselves are typically LESS complex than yours and most others.  The amps use just two tube stages, NO coupling caps at all / directly coupled, and are Single Ended !!! 

 

Once someone experiences a higher amplifier performance,.................... it becomes almost impossible to be satisfied, and live with less.

 

Also, Maynard, the amps I use are designed for MY simple highly-efficient speaker load.   NOT built for a usually 3 way speaker and a complex crossover.  Why do it otherwise ???   Build the amp, to fit the need. 

 

My speaker's  515B 15 inch woofer driver is operated direct and full range, ' have no crossover what so ever on the 15 inch.  A simple 12 dB network and L-Pad lays in an  802D compression driver.   

 

Simple high-quality-drivers, a two way speaker, mostly front horn loaded and nicely ......front-radiating.   After searching for 50 plus years, this truly satisfies my audio needs !!!   YMMV. 

 

Jeff 

 

                                               P1010021.thumb.jpg.02ca392f991421fd3d9beb02c68c0bcb.jpg

 

Front horn loading ( 135 Hz up ) and a direct front radiating high-quality fifteen inch driver, does things, mid-bass and up, IMHO, that a rear horn loaded woofer can not do.  Mild mods can be applied thoughtfully, to a stock VOTT A7-8.   Most audiophile - published mods, I have found, miss the mark.

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Hi guys.
Since 2012, I have a self-made lamp amplifier with 833 lamps (Gu - 48 analogue from the USSR). I'll tell you right away, I didn't do it, but I'm not an electronics specialist. I just love listening to music.
Amplifier - single-stroke in class A, 55 W when using 750 W.
For 6 years I brought his sound to my preferences: openness, speed, timbre. In my opinion, and the view of many who listened, it worked. the room I rented, it's not my design.IMG_7046.JPG

9DDF36FF-773C-4A9A-AB99-2A62DB14C361.jpeg

IMG-0bf43c8d5d668d939b06827c407b28e6-V.jpg

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3 hours ago, quadrokot said:

Hi guys.
Since 2012, I have a self-made lamp amplifier with 833 lamps (Gu - 48 analogue from the USSR). I'll tell you right away, I didn't do it, but I'm not an electronics specialist. I just love listening to music.
Amplifier - single-stroke in class A, 55 W when using 750 W.
For 6 years I brought his sound to my preferences: openness, speed, timbre. In my opinion, and the view of many who listened, it worked. the room I rented, it's not my design.

are these real Jubilees or DIY  -

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3 hours ago, quadrokot said:

Hi guys.
Since 2012, I have a self-made lamp amplifier with 833 lamps (Gu - 48 analogue from the USSR). I'll tell you right away, I didn't do it, but I'm not an electronics specialist. I just love listening to music.
Amplifier - single-stroke in class A, 55 W when using 750 W.
For 6 years I brought his sound to my preferences: openness, speed, timbre. In my opinion, and the view of many who listened, it worked. the room I rented, it's not my design.IMG_7046.JPG

9DDF36FF-773C-4A9A-AB99-2A62DB14C361.jpeg

 

15 inch woofers front firing on jubilees  cabs  -   bass reflex ----------------     can you elaborate on what you have accomplished with this modification , and any plans , specs you can share

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I had a Diy Jamboree based on original drawings from Dana Moore. The bass was powerful and large, but had a large peak of 12 dB at about 125 Hz. After which there was the same pit at about 250-300 Hz. Rock did not play in the absence of this range, there was no energy, the lack of which was not so noticeable in other genres. Unfortunately, the measurement screens were not preserved.
So, after consulting with Dana, I reworked Jamboree for direct 15 "speakers. The 200-300 Hz range got better, but the peak around 100 Hz remained big. I attribute this to Jamboree's own resonances. The bass seemed to play on the same note. , close to 100 Hz.
I was not able to reconfigure the crossover because I am not such an expert.
So I decided to make a box with a phase inverter for two 15 ".
The crossover was based on the ALK II, slightly modified its woofer link, replacing the coil with a different denomination.
All my dances around this wonderful Acoustics ended with an incredible sound. I am very pleased.
This is probably offtopic, the same theme for the 833 lamp.

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Іn six years of living with an amplifier on 833 lamps, I was able to compare it with many other tube, transistor and PWM amplifiers. These were Quody, Diinako, Scott, Audio Sculpture and others. None of them could match the 833 lamp. She paints great musical images, for example, the singer was standing at full height. The piano was as wide as natural.
Yes, high power consumption, in the anode of 1650 volts it causes respect and caution. It is hot near the amplifier in summer. But for such a sound you can tolerate everything.
One-stroke amplifier 55 watts in class A. At first, my amplifier worked with Jamo 909 R. It revealed their full potential.
Modern PWM amplifiers are better in bass, but they have not yet reached such midrange frequencies as the 833.
I liked that my one-beat play rock easily.

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On 6/27/2020 at 11:58 AM, quadrokot said:

Іn six years of living with an amplifier on 833 lamps, I was able to compare it with many other tube, transistor and PWM amplifiers. These were Quody, Diinako, Scott, Audio Sculpture and others. None of them could match the 833 lamp. She paints great musical images, for example, the singer was standing at full height. The piano was as wide as natural.
Yes, high power consumption, in the anode of 1650 volts it causes respect and caution. It is hot near the amplifier in summer. But for such a sound you can tolerate everything.
One-stroke amplifier 55 watts in class A. At first, my amplifier worked with Jamo 909 R. It revealed their full potential.
Modern PWM amplifiers are better in bass, but they have not yet reached such midrange frequencies as the 833.
I liked that my one-beat play rock easily.

 

 

The use of the term " one-stroke ' must be a meaning of ONE audio stage, sometimes in the USA also called a " spud " amplifier.  Do I have this correct??  Please confirm. 

 

If so, yes, a simple circuit is nice.   

 

I enjoyed seeing the speaker progression, from rear horn loaded bass, to front radiating direct woofers.  That is what I use also.

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On 6/27/2020 at 4:04 AM, RandyH 000 said:

are these real Jubilees or DIY  -

Apparently plans of the Dana Moore copies of Jubilee.

 

 

Funny how everyone wants to thank Dana Moore, but not PWK/Chief Bonehead. Probably because they PWK didn't publish plans for everyone to make. He is from the Ukraine so I'm sure he can't get Jubilee bins.

 

The state of the art has grown significantly from that clone/copy bin in what Roy is doing.

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Hi Jimjimbo,

i would be interested in buying a couple of your 833s.

I have a high feedback design underway based on Frank Blohbaum's Multiplied Transconductance Amplifier (MTA) philosophy.

1500V @ 180mA into 5K:6R OPT

Contact me off list if interested

timgrindell(at)gmail.com

stay safe

tim

 

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3 hours ago, dhsettim said:

Hi Jimjimbo,

i would be interested in buying a couple of your 833s.

I have a high feedback design underway based on Frank Blohbaum's Multiplied Transconductance Amplifier (MTA) philosophy.

1500V @ 180mA into 5K:6R OPT

Contact me off list if interested

timgrindell(at)gmail.com

stay safe

tim

 

@jimjimbo so that he sees this.

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9 hours ago, dhsettim said:

Hi Jimjimbo,

i would be interested in buying a couple of your 833s.

I have a high feedback design underway based on Frank Blohbaum's Multiplied Transconductance Amplifier (MTA) philosophy.

1500V @ 180mA into 5K:6R OPT

Contact me off list if interested

timgrindell(at)gmail.com

stay safe

tim

 

Hi Tim, sending you email.

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