I think you are expanding on exactly why I find the original poster's question a curiosity. While I have not worked in sound reinforcement for a number of years, even so, we had stereo bi-amped, tri-amped or quad-amped systems. Even a simple stereo bi-amp system requires four amps at a minimum.
It seems very retro to go with a monaural PA system with passive crossovers and high wattage. For that matter, it is also prohibitively expensive when you consider the cost of the components and crossovers that can handle that amount of power!
Lastly, any sonic advantage tubes might bring to the party are almost certainly lost with the environment (and passive crossovers). Add alcohol and no one is going to care anyway, so why go through all the expense?
Thank you Loren42 and Tubelab for commenting.
I guess I didnt explain my idea very well...
There are lots of points to comment on so I may forget a few, but basically my story is that I have been apart of the free party/rave scene in England for a number of years, and our rig was perfect for the job... Old, cheap, and sounded rubbish. I run events in hired venues for up to 1000 people and have always had to hire in PA equipment. I only graduated last year, but from working with a valve amp technician I brought up the question of building my own to use in these venues. I never really plan on taking this into a field.
Anyway, my mentor suggested a number of options and bi-amping was his best recommendation. Either that or go down the route that I believe Wavebourne (dont quote me) uses, and use MOSFETS or bipolar transistors at the output stage.
I am not offended Loren42, its just they dont teach you these things in uni so asking on this site will give me the biggest insite on the subject, even if it shows my lack of knowledge. And 1KW was mearly plucked out of the air.
Cheers
I guess I didnt explain my idea very well...
There are lots of points to comment on so I may forget a few, but basically my story is that I have been apart of the free party/rave scene in England for a number of years, and our rig was perfect for the job... Old, cheap, and sounded rubbish. I run events in hired venues for up to 1000 people and have always had to hire in PA equipment. I only graduated last year, but from working with a valve amp technician I brought up the question of building my own to use in these venues. I never really plan on taking this into a field.
Anyway, my mentor suggested a number of options and bi-amping was his best recommendation. Either that or go down the route that I believe Wavebourne (dont quote me) uses, and use MOSFETS or bipolar transistors at the output stage.
I am not offended Loren42, its just they dont teach you these things in uni so asking on this site will give me the biggest insite on the subject, even if it shows my lack of knowledge. And 1KW was mearly plucked out of the air.
Cheers
Even if the venue had excellent acoustics (fat chance) and the audience were all audiophiles, and the speakers were all up to the task (yeah, I'm dreaming, but) and you wanted to use the best equipment for the job, I would still look for a high powered SS amp for the low frequencies. It just makes sense. Then the decisions can be broken down to stereo or mono, bi or tri amped. So we are now looking at from 1 to 4 high quality amps. These can realistically be tube amps, and things like the OPT's can be tailored to the frequency response needs of the intended job. You can crank serious power through a small OPT if you exclude the low frequencies. The power is split up so you don't need 1KW from 20Hz to 20KHz out of one amp. With a system like this you would still get tube sound. The total system would be smaller, cheaper, and consume far less power than a single 1KW tube amp. Now do you take the cost, size, and weight savings and ramp it up to 2 or 3 KW?
On the other hand, I grew up near the University of Miami. During the 60's and 70's there were outdoor concerts held on their soccer field about once a month. I used to check out the equipment. The U of M sound system was tri amped using Crown DC-300's and Altec speakers. Didn't sound half bad, and was loud enough to disturb the peace in the sorrounding elderly afluent neighborhood. One afternoon I heard the loudest sound coming from the UM campus that I had ever heard, so I went to check it out. A British band called the Illusion (Did You See Her Eyes, 1969) had brought their own equipment. Stacks of Marshall Major heads (200 watts 4 X KT88) wired up to columns of 15 inch speakers, all running on some huge step up (115 to 230 volt) transformers. Yes there was several kilowatts of all tube power. An awesome sight, maybe 10 amplifiers all filled with Genelex KT88's!
Well, let's start at the beginning.
First, what type of events are these? Indoors, outdoors, combinations of each, etc. If you plan on working a lot of different venues you need to identify the worst case for each type of venue. Also, what type of audio will it be i.e., music, speech, both).
Ideally, if you can track down people or companies that have worked these venues before you can inquire as to what equipment was used and hopefully, how successful they were.
When you know the requirements of what you have to fill you can select the speakers needed to do the job that fills all venues. If you already have speakers, it still is a good idea to do this because you may find gaps or holes in your current gear that needs to be addressed.
The SPL efficiency of the speakers will let you work out what the minimum number of Watts required to achieve a desired sound pressure level. This is not trivial because room or outside acoustics play a part, so you must factor in a headroom factor to cover unforeseen conditions.
The next question is if you plan to do this as a hobby or are you trying to make money? If the latter, then a cost-benefit analysis will swing your purchase to solid state amps. They are more rugged electrically and physically, whereas tubes are more fragile and require periodic replacement, which is not cheap!!!
Another thing to consider, the more amps you have (i.e., tri-amping, etc.) the less stress on any one component. Also, buying an extra amp to keep as an emergency spare is cheaper than buying one mongo amp and a second mongo amp just in case.
On that thought... If you have multiple amps, loosing one will degrade the sound somewhat, but the show can go on. If you have only one amp and it goes, then you have 1,000 angry people in your face.
My bet would be buy used solid state equipment as cheap as you can and build a wonderful tube amp as a hobby for your flat.
Hi- Just stumbled across this thread. I am starting a project for a sound re-enforcement amp for another ravey event, Burning Man. Though my objectives are much less than yours (~70-100w for ~ 50 people in my camp; mainly background music).
Tubelabs approach sounds the best- divide up the power.
Tubelabs approach sounds the best- divide up the power.
Two words: "solid state"
A hybrid amp would be much more practical.
I designed my own with an ECC82 front end and a MOSFET output stage.
I can get upto 800watts out of it.
Everyone always talks watts when they mean loudness. It's really detrimental.
Start with very efficient speakers. The more efficient the better, fiberglass horns can be used for the bass bins for portability. HF drivers are generally already efficient. Use 100db+ mids 12"s. Really check phase issues at a couple different places in the room. Throw as many efficient speakers into each of the three bands as possible.
Tri amp. this will give you DB since the speakers and amps are not trying to reproduce such a wide Q. Active crossover with a high-order filter. or an overlap maybe, depends. Some multiband or parametric eq's before each power amp can help tailor the sound or resonance issues.
Use a class D solid state amp (light, cheap & portable) for lower frequencies where class D shines. Mids should be something like a big class AB tube or transistor amp. Highs could be an AB or A tube amp, or whatever.
Just some ideas I'd consider before trying to build a 1950s AM radio station instead. If you have to do it, use russian surplus ceramic transmitting tubes for certain, and the cooling system off a car engine attached into the generator.
Start with very efficient speakers. The more efficient the better, fiberglass horns can be used for the bass bins for portability. HF drivers are generally already efficient. Use 100db+ mids 12"s. Really check phase issues at a couple different places in the room. Throw as many efficient speakers into each of the three bands as possible.
Tri amp. this will give you DB since the speakers and amps are not trying to reproduce such a wide Q. Active crossover with a high-order filter. or an overlap maybe, depends. Some multiband or parametric eq's before each power amp can help tailor the sound or resonance issues.
Use a class D solid state amp (light, cheap & portable) for lower frequencies where class D shines. Mids should be something like a big class AB tube or transistor amp. Highs could be an AB or A tube amp, or whatever.
Just some ideas I'd consider before trying to build a 1950s AM radio station instead
. If you have to do it, use russian surplus ceramic transmitting tubes for certain, and the cooling system off a car engine attached into the generator.You can't beat good sensitive speakers as a starting point, 1 watt in and 96db out. From there you have to problem solve the output xformers and power supply.
As others have pointed out building xovers to handle the wattage you want to throw at them isn't cheap.
Driving tubes to 1KW out requires, in essence, another amplifier.
If you just use a rule of thumb that 2KW in nets 1KW out you can start looking at where does the 1KW that doesn't come out go?
I used to go to CES and once jokingly asked Vicktor of BAT audio when he was going to design an amplifier using my favorite triode, an 8877. I have a ham radio amplifier that uses one of those that can be run at 1KW out, constantly for 24 hours, higher on intermitent service, like ham radio, with 4KW on the plates, an easy 2KW out.
The tube requires a blower to constantly remove the heat.
Thank god their isn't any output transformer! We use a variable cap-inductor-variable cap.
Even when I know all of the supply caps have been discharged, I still get the willies thinking about working on something with 4KW on the plates. I find I develop a sloppy approach from working on 450V power supplies in my audio gear.
I've got an 8K xformer for my amp and have never bothered to install it. Fortunately, I just smile when I look at it--its awwwwsome to behold!!
Best of luck with your dream project.
Bob
As others have pointed out building xovers to handle the wattage you want to throw at them isn't cheap.
Driving tubes to 1KW out requires, in essence, another amplifier.
If you just use a rule of thumb that 2KW in nets 1KW out you can start looking at where does the 1KW that doesn't come out go?
I used to go to CES and once jokingly asked Vicktor of BAT audio when he was going to design an amplifier using my favorite triode, an 8877. I have a ham radio amplifier that uses one of those that can be run at 1KW out, constantly for 24 hours, higher on intermitent service, like ham radio, with 4KW on the plates, an easy 2KW out.
The tube requires a blower to constantly remove the heat.
Thank god their isn't any output transformer! We use a variable cap-inductor-variable cap.
Even when I know all of the supply caps have been discharged, I still get the willies thinking about working on something with 4KW on the plates. I find I develop a sloppy approach from working on 450V power supplies in my audio gear.
I've got an 8K xformer for my amp and have never bothered to install it. Fortunately, I just smile when I look at it--its awwwwsome to behold!!
Best of luck with your dream project.
Bob
You mean that a 1000 watt solid state amp would not be enough of a challenge?
I'm seeing the trifecta: cheaper, more reliable and better.
Done to death. Not better SQ, IAC - just more convenient. high powered SS amps tend to be coarse sounding at reasonable home listening levels. It's easier just to buy a 1000 watt SS amp (I have). I build my own tube amps, though.
I000 WATT SOUNDSYTEM
Hey
its worth doing///have done so myself finished my upper bass amp and sub bass amp this year...driving 4 18 inch scoops off the big amp....starting a pre in october and will be out next year couple of companies will wind the transformers for u...big differences in price and performance though
Hey
its worth doing///have done so myself finished my upper bass amp and sub bass amp this year...driving 4 18 inch scoops off the big amp....starting a pre in october and will be out next year couple of companies will wind the transformers for u...big differences in price and performance though
For building a large-ish tube amp, you can get a 1000 Watt Xantrex 600 V (XHR 600-1.7) power supply off Ebay for a few hundred dollars (auctions, not the buy-it-nows) that weighs 11 Lbs and fits in a briefcase. As George mentioned, there are Plitron 400 watt toroid OTs. And then some KT120s or whatever that will run off 600 V and a fan for cooling.
If you want to go more challenging yet, then look at the David Berning type switched impedance converter idea. Other switchmode variants available too. It uses switching Mosfets to develop the HV plus the output impedance conversion (the OT) using small switchmode ferrite xfmrs. Audio amplification still by tubes. This combo eliminates both the heavy power supply and the heavy OT. This can actually weigh less than a class AB SS amp of equivalent power, since no heavy heatsinks are required, just a fan. Can still use KT120 or whatever tubes. You could probably get 500 Watts audio this way in a suitcase sized unit that weighs 40 or 50 Lbs.
If you want to go more challenging yet, then look at the David Berning type switched impedance converter idea. Other switchmode variants available too. It uses switching Mosfets to develop the HV plus the output impedance conversion (the OT) using small switchmode ferrite xfmrs. Audio amplification still by tubes. This combo eliminates both the heavy power supply and the heavy OT. This can actually weigh less than a class AB SS amp of equivalent power, since no heavy heatsinks are required, just a fan. Can still use KT120 or whatever tubes. You could probably get 500 Watts audio this way in a suitcase sized unit that weighs 40 or 50 Lbs.
Ceramic tubes
Just as an aside, I have several good 4CX3000A and 4CX10000A EIMAC power pentodes I've been considering for HF linear amp (1-30 MHz) amateur radio projects.
When I dug up some of the tech data on these tubes, they were described as "power pentodes for audio amplifiers and HF radio amplifiers". Gees, a 10-kilowatt 4CX10000A, as an audio amp??? Just imagine...... Hhhmmmm.....
Just as an aside, I have several good 4CX3000A and 4CX10000A EIMAC power pentodes I've been considering for HF linear amp (1-30 MHz) amateur radio projects.
When I dug up some of the tech data on these tubes, they were described as "power pentodes for audio amplifiers and HF radio amplifiers". Gees, a 10-kilowatt 4CX10000A, as an audio amp??? Just imagine...... Hhhmmmm.....
Hi Charlie,
ok your thread is more than 1 -1/2 year old. Is your project are still actuell?
A question: did you ever build an valve amp? Even a small one? If your answer is no, try to begin with a smaller one and not such an challenging huge monster.
If your answer is yes, my suggestion is an amp with loads valves in parallel to achieve this amount of Watts. Plenty of valves in parallel keep the plate voltage low , therefore a low load impedance . That make the winding of the opt much more easier. nevertheless the opt will still be a big block of copper and iron. The power iron is not rocket science but will cost you also a lot of bucks. The estimated cost for the iron and the valves will alone somewhat of abt. 3500 quids. If you really going on these project please let us informed abt. the forthcoming.
Good luck.
regards
Wolfgang
from Hamburg
ok your thread is more than 1 -1/2 year old. Is your project are still actuell?
A question: did you ever build an valve amp? Even a small one? If your answer is no, try to begin with a smaller one and not such an challenging huge monster.
If your answer is yes, my suggestion is an amp with loads valves in parallel to achieve this amount of Watts. Plenty of valves in parallel keep the plate voltage low , therefore a low load impedance . That make the winding of the opt much more easier. nevertheless the opt will still be a big block of copper and iron. The power iron is not rocket science but will cost you also a lot of bucks. The estimated cost for the iron and the valves will alone somewhat of abt. 3500 quids. If you really going on these project please let us informed abt. the forthcoming.
Good luck.
regards
Wolfgang
from Hamburg
Last edited:
Hi Charlie,
me again. I found this little book in the internet. There are neat circuits inside, up to 1100 Watts.
http://rainers-elektronikpage.de/BABANI_Design_Handbook_PDF.pdf
regards
Wolfgang
from Hamburg
me again. I found this little book in the internet. There are neat circuits inside, up to 1100 Watts.
http://rainers-elektronikpage.de/BABANI_Design_Handbook_PDF.pdf
regards
Wolfgang
from Hamburg
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