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Author Topic: 1000 Watt tube amp  (Read 25558 times)

RMoore

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zmix

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Re: 1000 Watt tube amp
« Reply #1 on: March 24, 2010, 10:46:34 pm »

...bet it sounds Kilo

compasspnt

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Re: 1000 Watt tube amp
« Reply #2 on: March 25, 2010, 12:38:14 am »

Did Larry build that...?
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Larrchild

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Re: 1000 Watt tube amp
« Reply #3 on: March 25, 2010, 09:28:21 am »

index.php/fa/14520/0/
Looks like he switched from rows of KT-88s to a quartet of 813 transmitting tubes. 2500vdc on the plates!

The tough part with these amps is that the plate load is pretty hi-z so an output transformer that passes full HF is tough due to size and high-ratio.



But the Bass!  mmmmmmmm  Smile
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Larry Janus
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Jim Williams

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Re: 1000 Watt tube amp
« Reply #4 on: March 25, 2010, 12:20:32 pm »

In the late 1960's there was an exterminator in Venice CA off Pico Blvd. His name was Frank Cooley. He built tube guitar amps. They were called "TNT". Canned Heat used them exclusively. So did I. I had a blues band with the brother of Bob Hite, "The Bear", Richard. We also had 125 watt TNT tube amps, all 6CA7 based designs. They came with 15" JBL's and they were LOUD!

The 125 watters were the small amps. The bigger models were either 250 or 500 watts. He didn't stop there. He built a custom head for Canned Heat lead guitarist Henry Vestine.

That one was 3 feet long, weighed in at 150 lbs and put out 1500 watts. It used 16 KT-88 power tubes and very large transformers.
It was used at one concert, at Santa Monica Civic in 1969.

Henry was SO LOUD people began to leave the concert. Frank was also there and flipped out. He began pulling out power tubes from the rear of the amp during the show.

In 1974 I was in West LA Music and that head was there right in the middle of the floor, for sale. I guess it was just dropped there as no one wanted to hurt themselves moving it. I thought about that $300 price, for about 3 seconds. Then I remembered the shear damage that thing could do. Once I did fire up the 500 watter in my parent's back yard in 1970. Ten minutes later I had a crowd of friends from 2 miles away all wanting to check out the rock concert. I had a 50 foot cord from my Strat and it would still feedback uncontrollable, too much even for me!

I memoriam to Frank, Henry and the Heat, I designed the Basson Sound guitar amps in a similar way. They are 120 watts, 4 6CA7 power tubes and enough SPL's to kill small rodents. I love them.
www.bassonsound.com
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Larrchild

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Re: 1000 Watt tube amp
« Reply #5 on: March 25, 2010, 10:17:25 pm »

Ryan, didn't Tubby or Scientist build some leviathan tube amp?
Maybe it was another dubster but I think you posted pix.
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zmix

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Re: 1000 Watt tube amp
« Reply #6 on: March 26, 2010, 10:22:50 am »

Larrchild wrote on Thu, 25 March 2010 22:17

Ryan, didn't Tubby or Scientist build some leviathan tube amp?
Maybe it was another dubster but I think you posted pix.


King Tubby would have been the guy... I'd love to see some of his work!

RMoore

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Re: 1000 Watt tube amp
« Reply #7 on: March 26, 2010, 11:30:19 am »

The reggae sound system peeps have a long tradition of DIY / home brew PA's and amps. I rather suspect this particular 1000W amp may have been built for that purpose - some bass rumble, but not 100% sure about that.

a 1500w guitar amp? That's just insane (!)...


Here's King Tubby with his homebrew set up for his 'Hometown Hifi':

http://1.bp.blogspot.com/_uo_eC6uZluY/RoWdnOuZe3I/AAAAAAAAAPc/NhmQ1MDuESg/s400/king_tubby.jpg

No idea as to the wattage - it sure looks d*mn cool..

I've been told by several people in JA that Tubby's was not the loudest system but was the best sounding by far at rockin' the block parties.

Tubby's amp was apparently destroyed in the mid 70's by police who felt the wrong crowd attended his events & KT gave up sound system activities thereafter..


This ultra-legendary figure in the UK, Jah Shaka, ran his system on homebrew tube amps in those metal crates - the xformers looked like some kind of huge WWII surplus units:

http://www.jim-baker.co.uk/img/jah_shaka_3.jpg
http://www.jim-baker.co.uk/img/jah_shaka_1.jpg

The system was stolen a few years back, but I was lucky enough too experience it in the past - sounded awesome..
Sessions similar to this clip, same era, same club 700-1000 people: http://www.youtube.com/watch?v=0PONu4SkzeE

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People's Republic of Ryan

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By the end of today, another day is gone forever. You will never get it back.
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MDM,

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Re: 1000 Watt tube amp
« Reply #8 on: March 29, 2010, 08:01:35 am »

sheesh... and I thought the MC-3500 was heavy at 125 lbs
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RMoore

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Re: 1000 Watt tube amp
« Reply #9 on: March 30, 2010, 06:58:14 am »

Some more UK tube PA sounds:


London's Jah Observer @ Notting Hill....  gotta love the shelf sagging under the weight!


http://farm2.static.flickr.com/1149/1251402109_b1cf4ea44d.jpg



And a  'revive sound' Downbeat Melody in Bristol running a collection of original vintage 1950's / 1960's boxes imported from JA including an original King Tubby 1960's bass bin - pretty cool..


Views of their mondo 'Tip-A-Tone' tube amp with lunar lander module lamps plus some others, including an amp  which literally goes to '11' here:
<http://www.lickitback.co.uk/downbeat.php>



http://www.lickitback.co.uk/art/downbeat-photo.jpg
http://i176.photobucket.com/albums/w190/kidbingo/TubbysHTHF.jpg
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People's Republic of Ryan

http://www.myspace.com/twilightcircus
 http://www.youtube.com/user/Ryonik
 
By the end of today, another day is gone forever. You will never get it back.
We must never let up for a second. Work harder at every single thing - Terry Manning

 You miss 100 percent of the shots you never take - Wayne Gretzky

bruno putzeys

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Re: 1000 Watt tube amp
« Reply #10 on: March 30, 2010, 07:21:04 am »

Larrchild wrote on Thu, 25 March 2010 14:28

The tough part with these amps is that the plate load is pretty hi-z so an output transformer that passes full HF is tough due to size and high-ratio.

Not sure if I get that. The turns ratio goes down as you parallel more tubes. So HF should be quite easy to get right.
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Larrchild

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Re: 1000 Watt tube amp
« Reply #11 on: March 30, 2010, 08:56:20 am »

In his circuits with rows of tv tubes or KT-88's, the load is reasonable as you say, but with 4 transmitting tubes, it's still pretty high. (9500 ohms) I'm saying transmitting tubes like 813's operating at higher voltages seem to want a fairly hi-Z load. Smile
Looks like a pair of 813's in AB1 want 19 k load resistance @2500 vdc.
   http://faculty.frostburg.edu/phys/latta/ee/wing813amp/813dat asheet1.jpg
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Larry Janus
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RMoore

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Re: 1000 Watt tube amp
« Reply #12 on: March 30, 2010, 10:04:31 am »

Note: the site layout is a little unclear but it would appear he's done several different 1000W amp projects using 813, 807 or KT88's..


1000w from 4 tubes - madness (!).. I love this idea though.

I wonder how the sonics of the 813 compare with the KT88?

Apparently there is the possibility of arcing with these 813's if there is a failure mode..


Schematic:

http://www.chambonino.com/construct/constwire2.html

From the builder's site:

http://www.chambonino.com/construct/const9.html


Hello, all you high-powered tube amp maniacs out there! Having recently been commissioned to design and build four 1kw tube amps, ........yes FOUR!!....... , I decided to use four of the classic 813 tubes rather than multiples of KT88's. In-fact twenty KT88's would have been needed to get the 1000 watts!



and



   (1). I am overwhelmed (but not surprised) at the immense amount of e-mails and phone calls that I have received about this project since it was placed on the site a few months ago. Thank you for all your interest. I realize it is hard to find something like this amplifier elsewhere!! And………

   (2). If any of you out there ever tackle this enormous baby (or even a 500 watt version with 2 x 813’s and just half the HT current.....everything else stays the same apart from a plate-to-plate load of 19,000 ohms for just two bottles) please remember that you are working with extremely, potentially lethal voltages!! Apart from the obvious 2,500 volts on those top-caps, even the 750 volt screen (grid 2) supply and the lesser 500 volt rail for the pre-amp and drive can also stop the heart!! Be very careful!

   !

OK, having gotten that off my chest (pardon the pun!) I will try here to cover all I can to help you. Over the many years that I have repaired, rebuilt, designed and built valve (tube) amplifiers, I have many-a-time stuck to a fairly rigid “tried and tested” formula learnt from these many years of experimentation and results. The CBA-500 (please see this article) follows a similar design pattern to this CBA-1000.

My own designed phase splitter circuit (ECC81) and directly coupled cathode follower/push-pull driver (ECC82/12BH7) is “world beating” and has never let me down! On the CBA-500; the twelve EL36/6CM5/EL360’s needed quite a bit of drive and this can be barely achieved straight from the phase splitter tube. We need a low impedance cathode follower supply/drive to do this, hence the ECC82. In the case of the CBA-500 the HT line is only about 435 volts. This is a trifle low for the push-pull driver so, a crafty but simple and effective trick here is to stand the cathode resistors from the said driver tube not on ground but…….on the minus, negative bias rail. This in turn now puts a greater potential across the driver tube (e.g. HT @ 435 volts but now with the -52 volts bias rail added gives us a total usable voltage of 487 volts), raising both the drive voltage and clipping points. (We always need the drive to be clean, unclipped before the output stage clips!). The other point I must make here is the fact that most bias windings on “off the shelf” transformers are usually of only a few milliamps. This being the case, we wouldn’t be able to use it for this purpose. I therefore always wind my bias windings for at least 300ma or more. This then leaves plenty of headroom for using the bias winding for just such issues as helping the driver tube, along with other items such as series connected DC pre-amp heaters and various relays etc.

On this amplifier, being the CBA-1000, the HT supply for the pre-amp/drive stages is already around 500 volts and generally speaking would be adequate but, although 813 tubes are reasonably efficient and don’t need excessive amounts of drive, (about 180 volts grid-to-grid to achieve the 1000 watts from four), I still opted for the idea of placing the push-pull driver cathode resistors onto the bias rail; this time of around -122 volts. This gives us around a total of 620 volts to play with on the driver tube!! Using a 12BH7 instead of the ECC82 (the 12BH7 being much beefier) gave me at least a further clean, unclipped drive of 20 volts above the required level and is still clean well after the output stage clips! Brilliant! The 12BH7 does run a little warm but……is fine and comfortable at this.

I have now included the SCHEMATIC DIAGRAM for this beast on the site for your help and interest. I think most of it is pretty self-explanatory; any questions please, just e-mail me.

I have always run my pre-amp/driver heaters on DC, right back as far as the sixties!! This is very beneficial all round. As the 12BH7 has a higher heater current than the ECC8? series of tubes, I have done a paralleled 6.3 volt DC chain instead on this amplifier. (Please see power supply schematic: “Y Y” heaters).

For those sufficiently knowledgeable to notice, I always tie the bottom end of my individual bias pots straight on ground. This is not normally a good practice as obviously the pots can then turn the bias off completely to the said tube(s), but….anybody who understands this would not allow this to happen anyway, and would always make sure that there was sufficient bias on the tubes’ grid 1’s before powering the amp(s) up. My reason for doing this is because it keeps the bias supply as low as possible from an impedance point of view and “rock solid”. I also use the 20 turn cermets pots as this too gives very good smooth and accurate setting up of the individual bias per tube. Lastly on this point, I also use 47uf caps on the wipers (output) of each cermets pot too. This also helps keep things “rock solid, accurate and smooth” on the individual bias adjustments.

Moving on, the 20 turn Cermets pot across the plates (anodes) of the phase splitter tube (ECC81) is such a simple, yet extremely effective idea. Usually, on virtually all amplifiers this would be two fixed value resistors, and yet, this simple addition balances the phase splitter tube, the push-pull driver tube, all associated components for both the afore said tubes, all the output tubes (no matter how many) and any deficiencies within the output transformer; all in one fail swoop! This works wonders. Try it and see!

As regards the pre-amp stages, once again I think the schematic’s are very self explanatory. If you didn’t wish to include the very front-end and tone circuits, then you just simply stop at “pre-amp schematic number two” and your input is as a slave-amp would be. If however, you did decide to go the “whole-hog” and build my own designed front-end pre-amp section too, then I can assure you that you will not be disappointed! My own-design tone circuit is incredible, even though it doesn’t use a “middle control”. I have designed this tone circuit in such a way so that when the bass control is increased, this brings in with it the low-mid. Similarly when the treble control is increased this brings in the high-mid along with the presence too. The combination of the two controls is absolutely breathtaking!! If you aren’t “gob-smacked” with my tone circuit, I’ll eat my hat! (and I do wear one!).

Two final points here, and touching back onto the fact that this amplifier uses extremely high voltages. (Well, they are high as far as most commercial amplifiers are concerned.)

   (1). The two F,1amp fuses on the + and – ends of the main 2,500 volts HT rail should preferably be of the inch and a quarter type (32mm), and should have plastic covers over them, with all connections covered with shrink-sleeving too. Both fuses should also be mounted on a single (each) insulated pillar, and a minimum of one inch (25mm) from the chassis. In the event of a blown (shorting) 813 tube, once either (or both) of these fuses pop there is a chance of arcing if the fuse length is too short and/or too close to the chassis with connections exposed! And finally……….

   (2). For the same reasons as above, the four 1ohm, 1%, .6 watt resistors (.6 watt is fine, the voltage drop across these is miniscule) need to be mounted at least one inch (25mm) away from each other, and at least one inch (25mm) from the chassis too. When one of the 813 tubes becomes short or flashes across inside (as happened on this prototype a couple of times with faulty tubes bought on EBay!!), this resistor, as well as being your reference point for each individual tube's bias, also acts as a fusible resistor too. However, when this resistor blew open on the prototype, the high voltage arced across to the others adjacent to it. Keeping them apart would stop this problem occurring.

Enjoy the amp, enjoy the project but...........please be careful of those high voltages!!

Cheers for all your continued support and interest.

John.



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People's Republic of Ryan

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By the end of today, another day is gone forever. You will never get it back.
We must never let up for a second. Work harder at every single thing - Terry Manning

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Larrchild

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Re: 1000 Watt tube amp
« Reply #13 on: March 30, 2010, 10:43:50 am »

Svetlana once took a 4CX250 external anode tetrode (forced-air all-metal transmitting tube) tube die and built it as a triode with a desired load of about 700 ohms.
Dunno if it's still around, but that had promise. (if you put it in another room to overcome the blower!)
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Larry Janus
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Jim Williams

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Re: 1000 Watt tube amp
« Reply #14 on: March 30, 2010, 11:38:40 am »

For those interested in mondo power tube amp design, Electro Harmonix has released the new KT120 power tube. 60 watts each and you can do some severe damage with those. Maybe I'll replace the GE6550's in my 1966 Deluxe Reverb with a pair of those. It could win the mighty small amp award. Great for small clubs when no one suspects the little amp as the offender.
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RMoore

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Re: 1000 Watt tube amp
« Reply #15 on: March 30, 2010, 11:47:08 am »

Larrchild wrote on Tue, 30 March 2010 16:43

Svetlana once took a 4CX250 external anode tetrode (forced-air all-metal transmitting tube) tube die and built it as a triode with a desired load of about 700 ohms.
Dunno if it's still around, but that had promise. (if you put it in another room to overcome the blower!)


Bizarre!

I found an internets thread from '99 discussing 'London Power Amps' using 4CX250B in some models

http://archive.ampage.org/threads/0/ampgen2/014942/4CX250_tu bes_in_London_Power_amps-1.html

6/1/1999 6:15 PM
Pascal
   4CX250 tubes in London Power ampsThis company uses these unusual tubes in the power section of certain amps and seem to get quite a good amount of wattage from them when compared to the usual tubes we see in amps (6L6, EL-34 and company). Is London Power the only amp maker to use these tubes for guitar amps and does anyone have playing experience with these tubes and/or amps? How do they hold up tone wise. The canadian amps are very pricey so I was wondering if the money is worth it. Also, has anyone homebrewed with these tubes??

6/1/1999 7:04 PM
Dave Chun
   If I remember correctly, the 4CX250s are triodes more suited for RF applications (they can dissipate over 250W each.) There's lots more info at the Svetlana website, www.svetlana.com.

6/2/1999 12:57 AM
Bruce
   A pair of 4CX250s in push pull class AB1 at audio frequencies will put out way over 600 watts with the right power supply!  
Try and find an OT for them though! $$$$  
Bruce

6/2/1999 5:16 AM
Dave Chun
   The London Power Bass Amp does just that - a pair of 4CX250s for 700w. I emailed them about the OT and it's a custom Hammond type that weighs *35 lbs.*





http://www.londonpower.com/spectext.htm



If you really need more power, check out our SUPER SCALER models. The SUPER SCALER v700 uses the same 4CX250 power tubes the legendary SPECTRUM 700 used. Half the size of a 6L6 but capable of outputting over 800W per pair. Utter reliability, as witnessed by their aviation and military uses in radars and transmitters in tanks, ships, planes, and anywhere microphonics or failure could not be tolerated.

The SPECTRUM integrated amps are built like our other head-style amps, in a steel Hammond chassis, with venilated cover and wooden ends with flip-uphandles. A custom ToroidTech toroidal power transformer with dual primaries assures world-wide mains compatibility. Our custom Hammond output transformer, PEC sealed military pots and Switchcraft open-frame jacks are all chassis mounted. Solen polypropylene filter caps, Wima and Philips signal caps, metal-film and flame-proof metal-oxide resistors mounted on Teflon circuit cards are hand-wired for a lifetime of service. The usual Twenty Year Warranty applies to everything except the tubes and reverb tank.

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People's Republic of Ryan

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By the end of today, another day is gone forever. You will never get it back.
We must never let up for a second. Work harder at every single thing - Terry Manning

 You miss 100 percent of the shots you never take - Wayne Gretzky

Larrchild

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Re: 1000 Watt tube amp
« Reply #16 on: March 30, 2010, 12:00:11 pm »

A generic 4CX250 doesn't have a low-z load like this special triode version. They used less distance from other elements to the plate to lower the Z. This prohibits higher operating voltages for obvious reasons.
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Larry Janus
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RMoore

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Re: 1000 Watt tube amp
« Reply #17 on: March 30, 2010, 12:01:31 pm »

Jim Williams wrote on Tue, 30 March 2010 17:38

For those interested in mondo power tube amp design, Electro Harmonix has released the new KT120 power tube. 60 watts each and you can do some severe damage with those. Maybe I'll replace the GE6550's in my 1966 Deluxe Reverb with a pair of those. It could win the mighty small amp award. Great for small clubs when no one suspects the little amp as the offender.



Nice!

http://www.univalve.net/vbulletin/showthread.php?p=22758
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People's Republic of Ryan

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By the end of today, another day is gone forever. You will never get it back.
We must never let up for a second. Work harder at every single thing - Terry Manning

 You miss 100 percent of the shots you never take - Wayne Gretzky

RMoore

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Re: 1000 Watt tube amp
« Reply #18 on: March 30, 2010, 12:02:59 pm »


With these absurdly high voltage tubes I'd be a little worried about the amp turning into a Tesla coil... what do you guys think?

http://i.telegraph.co.uk/telegraph/multimedia/archive/01388/Arcing-ladder-back_1388431i.jpg
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People's Republic of Ryan

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By the end of today, another day is gone forever. You will never get it back.
We must never let up for a second. Work harder at every single thing - Terry Manning

 You miss 100 percent of the shots you never take - Wayne Gretzky

bruno putzeys

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Re: 1000 Watt tube amp
« Reply #19 on: April 01, 2010, 07:06:38 am »

Larrchild wrote on Tue, 30 March 2010 14:56

In his circuits with rows of tv tubes or KT-88's, the load is reasonable as you say, but with 4 transmitting tubes, it's still pretty high. (9500 ohms) I'm saying transmitting tubes like 813's operating at higher voltages seem to want a fairly hi-Z load. Smile
Looks like a pair of 813's in AB1 want 19 k load resistance @2500 vdc.
     http://faculty.frostburg.edu/phys/latta/ee/wing813amp/813dat asheet1.jpg

Ah right. I should've done my homework there (I only looked at the posted pic which showed 8 smaller tubes). 9500 is high.
Jim Williams wrote on Tue, 30 March 2010 17:38

It could win the mighty small amp award.

I'm afraid I'll always win that one. Twisted Evil

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Larrchild

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Re: 1000 Watt tube amp
« Reply #20 on: April 01, 2010, 09:05:41 am »

Slightly off-topic.. Great finally meeting you at AES! Smile
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Larry Janus
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Larrchild

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Re: 1000 Watt tube amp
« Reply #21 on: April 01, 2010, 09:48:56 am »

RMoore wrote on Tue, 30 March 2010 10:04


Apparently there is the possibility of arcing with these 813's if there is a failure mode..


He's running this thing at Max rated plate voltage and is totally asking for trouble. I never ran 813's above 2250 vdc.
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Larry Janus
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John Monforte

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Re: 1000 Watt tube amp
« Reply #22 on: April 03, 2010, 12:37:06 am »

At 2500 volts, won't it generate x-rays?
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Larrchild

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Re: 1000 Watt tube amp
« Reply #23 on: April 03, 2010, 07:50:09 am »

Hence the term "more transparent".
Seriously, just barely.
> 10kV they become an issue.
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Larry Janus
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Moby (Mike Diack)

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Re: 1000 Watt tube amp
« Reply #24 on: April 04, 2010, 04:16:38 pm »

Sometimes 2 output tubes is enough.
Here is a Mullard design using MZ2-200 bottles (sorta like a 212 with a bowler hat)
http://www.r-type.org/static/mz2200.htm
And a locally made version of it that I inherited
(Used to power dozens of Vitavox horns at religious rallies in the '60s). 58 on stand is for scale.
index.php/fa/14574/0/
M
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Larrchild

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Re: 1000 Watt tube amp
« Reply #25 on: April 04, 2010, 05:06:25 pm »

Mike, I suspect a classified ad in Jamaica's "Gleaner" would provide a very healthy sum from one of the many thermionically-faithful denizens. Smile
Very Nice!
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foreignlove

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Re: 1000 Watt tube amp
« Reply #26 on: February 28, 2011, 08:43:31 pm »

Love the amp!
Does any one know anyone in USA who is able to build 500- 1000 watt tube amps. Cant seem to find anyone. Thanks
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Mike Cleaver

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Re: 1000 Watt tube amp
« Reply #27 on: March 01, 2011, 02:04:10 am »

Stephen Sank used to have a picture of a one off RCA power amp that delivered either 500 or 1000 watts IIRC.
He had it up for sale.
Don't see it on his site anymore.
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Jim Williams

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Re: 1000 Watt tube amp
« Reply #28 on: March 01, 2011, 11:20:52 am »

bruno putzeys wrote on Thu, 01 April 2010 04:06

Larrchild wrote on Tue, 30 March 2010 14:56

In his circuits with rows of tv tubes or KT-88's, the load is reasonable as you say, but with 4 transmitting tubes, it's still pretty high. (9500 ohms) I'm saying transmitting tubes like 813's operating at higher voltages seem to want a fairly hi-Z load. Smile
Looks like a pair of 813's in AB1 want 19 k load resistance @2500 vdc.
      http://faculty.frostburg.edu/phys/latta/ee/wing813amp/813dat asheet1.jpg

Ah right. I should've done my homework there (I only looked at the posted pic which showed 8 smaller tubes). 9500 is high.
Jim Williams wrote on Tue, 30 March 2010 17:38

It could win the mighty small amp award.

I'm afraid I'll always win that one. Twisted Evil




Yea, Hypex. Did you ever finish that 2k watt module?

Back in 1977, there was a tweed Fender Champ done up by Red Rhodes. It was used in a booth at Namm. He gutted it, built two chassis, one on top, one on the bottom. He fitted 6 kt-88's in it with 2 massive transformers.

This was a 200 watt Champ! Every 10 minutes they would crank it up. By the time the SPL meter man came by, it was off. They never found the source of that volume, no one ever suspected it was "The Champ".
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bruno putzeys

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Re: 1000 Watt tube amp
« Reply #29 on: March 02, 2011, 02:55:44 am »

The 2k module has been is in production for a year now. A higher performance one is slated for Q3 of this year or so.
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