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Posts posted by seti

  1. My friend and I finished another pair of amplifiers. These were a real mission. I spent so much time on these. They are supposed to be 90wpc which they are but they clip like crazy. They are super clean up to 75wpc.

    2 x 5ar4, 2x od3, 2 x 6sn7, 2 x kt90..... There was a 12au7 preamp stage but we ripped it out. We add JJ and Hayseed caps and also two test points and pots for setting bias. They are still pretty much Allen 90 organ amps but with a beefed-up power supply.




    • Like 6
  2. 7 hours ago, henry4841 said:

    I misunderstood the kind of hum you are having. I was under the impression you were talking about mechanical hum coming from the transformer itself but what you are saying is you are hearing hum from your speakers. Sometime it can frustrating finding hum coming from the circuit itself. I like the software program called Arta which will show which you have 60hz or 120hz with ease. Distinguishing 60hz from 120hz by ear is not something I am good at but is easily seen with Arta or any distortion analyzer. 


    If it is noticeable with 84db speakers you definitely do not want to hook it up to Klipsch speakers. 


    The hum could be circuit or transformer laminations or maybe both.

    Yeah we still got some work to do. I'm optimistic we can knock the hum down.  You know how it is when you just finish a big build and your just amazed any sound comes out at all. That is how I am anyway. I'm curious about the actual power rating and distortion measurements. That should follow.

  3. 2 hours ago, henry4841 said:

    As I am sure you know transformer hum is usually associated with being pushed to hard. Unless they are unreasonbly hot I would probably just turn the music up until you can no longer hear the hum. Being older than the amps I hum a little myself. 


    Excellent looking rebuild. 



    I don't think it is being pushed too hard as it is running lower voltage and current than spec. It was over 600v now it is 550v. The 0d3 cuts the voltage to the driver stages to around 300v.  We even removed a preamp stage then installed a larger potted choke. All the caps are cool after an hour of running. All the transformers and chokes not even warm. We are going to do some distortion and power testing and then try to find the hum. I can't tell if it is 60hz or 120hz right now. I've never had a tube amp this powerful. My bench speakers are 84db1w1m if I hear hum on this I'm scared of 107db 1w1m..... 


    This was something I had to get out of the way. If I can get it to a point where I am happy with it I might ebay or audiogon it so I can buy parts for other projects.







    I bought these monoblocks many years ago from a Little Rock Central High School teacher. I sent them to hot glass audio for a rebuild. Anyone who remembers that con knows it was a miracle I even got them back. He broke all NOS tubes in shipping. I sold them to my brother because I was frustrated but he just sold them back to me. The nightmare continues. I completely gutted them and rebuilt them from scratch but I did have professional help. I added bias adjustments removed a 12AT7 preamp section and upgraded power supply with a beefier choke and caps. The power tubes switched from, 6550 to KT90's which are from the collection I inherited from Daddy Dee. Thanks again to Daddy Dee. The tube compliment is 2 x KT90, 2 X 5AR4, 2 x OD3, and 2 X 6SN7. They sound really good when turned up but still a little transformer hum to work out. I need to tighten them down. Not sure I need freaking 90 watt amps.



    • Like 7
  5. 2 hours ago, mark1101 said:

    Have jury duty this week.  So far excused Monday/Tuesday.  As long as I'm excused Thurs and Fri I will get last minute flight/room/car and should be there.  Somebody please save me a seat in lab listening room late Friday.  Have to hear those Jubs again.




  6. On 3/4/2023 at 7:55 PM, MMurg said:

    From https://www.klipschmuseum.org/blog/2023/2/14/pwk-birthday-bash-2023


    Friday, March 10 – Listening Sessions at the Klipsch Lab featuring JUBILEES!


    Max 10-12 people per session! Session times: 10:00 AM-12:00 PM, 1:00 PM – 3:00 PM, and 3:00 PM – 5:00 PM


    MUST pre-register for the Listening Sessions at the Lab! To register: email beckie@klipschmuseum.org


    (Include your name and session time preferred.) (Free Event)


    Funny thing is I  think I am the one that posted that lol.......



    • Haha 1
  7. 22 hours ago, Chief bonehead said:

    I will have the jubs setup on Friday in hope engineering listening lab for those who want to hear them in a typical listening room. We will also have the mclaren 905’s protos at the visitors center playing. I hope to have it where you can listen to your own selections. 


    What time does this start on Friday?

  8. 8 hours ago, richieb said:

    For shites and grins let’s say the kickstarter falls short of the goal for publication. Money is returned and no copies 

    are printed. For all the work and hardship(s) people have endured what sense does it make to basically call the 

    project a failure and publish nothing? We see “prototype” books, where it will be printed, on what materials, etc. and 

    yet it’s possible a tangible product gets the axe? This makes no sense - 


    This is just how crowd funding works. I'm cautiously optimistic we will make it... If we don't make it would you like to publish for the museum? LOL...



  9. 1 hour ago, KT88 said:

    I think that's a good idea. I would additionally offer a similar amp in the same Metropolis movie like cabinet but without electronic crossover...for all lovers of Cornwall, Heresy, LaScala and Klipschorns from today's production. I bet there will be buyers if the price is adequate but doesn't shoot into unaffordable spheres, maybe a few $K might be attractive. No one would have to ask if these amps would be a good match for Klipsch Heritage speakers.


    I believe Cary Audio did a Klipsch specific amplifier.

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