I always hope it's initial ignorance and enthusiasm settling into reality and more modest, reasonable projects being pursued.
500W is indeed too small amount of power for so ambitious project.
1200W push-pull GU81M amplifier based on Russian UPV-1.25 is exactly what thread author should be looking for.
Amp is very stylish, small and compact, weighting only 200 Kg (441 lbs), easy transportable with a truck.
Additionally, it could serve as green energy saver for a house ("dacha") on the outskirts of Siberia during long and cold winter.
Full article can be found in Rusian magazine called "Radio", year 2007, Nr 4 (April). Use Google translate if necessary.
1200W push-pull GU81M amplifier based on Russian UPV-1.25 is exactly what thread author should be looking for.
Amp is very stylish, small and compact, weighting only 200 Kg (441 lbs), easy transportable with a truck.
Additionally, it could serve as green energy saver for a house ("dacha") on the outskirts of Siberia during long and cold winter.
Full article can be found in Rusian magazine called "Radio", year 2007, Nr 4 (April). Use Google translate if necessary.
Attachments
"I always hope it's initial ignorance and enthusiasm settling into reality and more modest, reasonable projects being pursued."
Amen to that.
--------
"Parts Express sells a 200W speaker line matching transformer for about $60. With a primary side impedance of 25R, this thing offers an attractive fix for the major drawbacks of tube OTL power amps. ...."
That would appear to be converting 40V to 70V, not much of a ratio.
( V*V/R = 200W V = 40)
---------
"1200W push-pull GU81M amplifier based on Russian UPV-1.25 is exactly what thread author should be looking for.
Amp is very stylish, small and compact, weighting only 200 Kg (441 lbs), easy transportable with a truck."
3500V B+, 441 lbs, truck
Ummm, no comment needed I think. Just reinforce the flooring and provide a garage door for the truck.
Amen to that.
--------
"Parts Express sells a 200W speaker line matching transformer for about $60. With a primary side impedance of 25R, this thing offers an attractive fix for the major drawbacks of tube OTL power amps. ...."
That would appear to be converting 40V to 70V, not much of a ratio.
( V*V/R = 200W V = 40)
---------
"1200W push-pull GU81M amplifier based on Russian UPV-1.25 is exactly what thread author should be looking for.
Amp is very stylish, small and compact, weighting only 200 Kg (441 lbs), easy transportable with a truck."
3500V B+, 441 lbs, truck
Ummm, no comment needed I think. Just reinforce the flooring and provide a garage door for the truck.
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I remember back in the '70s a letter from Audio Research announcing a "Dual 150" amp, which included this quote: "Note: This unit operates at idle at 1500 watts, dissipated as heat. Provision should be made for the anticipated environmental temperature increase."
We got a 5-ton AC system for the sound room, and then Audio Research didn't build it.
We got a 5-ton AC system for the sound room, and then Audio Research didn't build it.
Sounds like they were the inventors of "vaporware".
How about just training a horse to tap its foot to the music.
How about just training a horse to tap its foot to the music.
Well, I see it as 70V to 40V, or 3:1 impedance step-down, which would make an 'OTL' output stage a LOT happier. This xfmr has a 4R tap as well, so potentially the primary Z could be 50R if an 8R load was attached there. This changes output stage requirements to 280Vpp @ 2.8Ap and puts the supply rails near +/- 200VDC, which is pretty tame for a 200W tube amp.
You boys sure are chatty.......
My ignoramus brain spent most of the day topping out a small stand of Loblolly and Longleaf pines some beetles had got into.
Which is more dangerous high voltage or high heights? The answer is ground(men) LOL.... 😕😕😕 oh I got a nice shakin when they let one top swing....
Yes 500+w is off the table.
What I don't get (and I have been studying) is how does the massive jump occur from a Dynaco A431 (10lbs?) capable of 120W according to this A431S Triode USA Output Transformer for Dynaco 4300 Ohm 60W/120W for Dynaco MADE IN USA
Then we go straight to 400lbs?
Obviously there is some range between 10lbs-400lbs but the weights get out of control much sooner than I'd expected.
DAMN YOU REALITY!!!! I'LL GET YOU SOME DAY!!!
Now after reading this I'm going to go look at my current stock and do some thinking.
Output Transformer Impedance
I already have a OPT with physical measurements nearly identical to that Triode A431S and built for a 2R load.
Time to go play with these power transformers....
My ignoramus brain spent most of the day topping out a small stand of Loblolly and Longleaf pines some beetles had got into.
Which is more dangerous high voltage or high heights? The answer is ground(men) LOL.... 😕😕😕 oh I got a nice shakin when they let one top swing....
Yes 500+w is off the table.
What I don't get (and I have been studying) is how does the massive jump occur from a Dynaco A431 (10lbs?) capable of 120W according to this A431S Triode USA Output Transformer for Dynaco 4300 Ohm 60W/120W for Dynaco MADE IN USA
Then we go straight to 400lbs?
Obviously there is some range between 10lbs-400lbs but the weights get out of control much sooner than I'd expected.
DAMN YOU REALITY!!!! I'LL GET YOU SOME DAY!!!
Now after reading this I'm going to go look at my current stock and do some thinking.
Output Transformer Impedance
I already have a OPT with physical measurements nearly identical to that Triode A431S and built for a 2R load.
Time to go play with these power transformers....
If i wanted "tube sound" in a subwoofer, I'd couple a tube preamp with a lot of 2nd order harmonic distortion to a class-D monoblock rated for at least 3x the RMS power rating of the woofer.
Because it's not that they lie in the class-D specs, it's that the power vs. thd graph is extremely telling. They also lie, but that's not the point.
Because it's not that they lie in the class-D specs, it's that the power vs. thd graph is extremely telling. They also lie, but that's not the point.
EDIT, it was last coupled to a amp advertising 1200w peak and the only issue was amp clipping and knocking the dust cap loose 🙂
But you meant a class D amp rated at 1500 rms correct?
The car audio world doesn't seem to mingle well with the HIFI world.
The "indestructible trunk thumper" subs are awful impressive but compliance and mass make them hard to drive outside the 12vdc unlimited amps environment. (not unlimited but you know what I mean)
I'd also been looking at all the class T amps so cheaply available now but need to read some threads on how or IF tube preamps fit in that equation.
Class T is totally new to me.
That would be for driving higher sensitivity woofers, not this beast.
EDIT, I don't wanna talk about class T, just saying that I'm looking into all the possibilities.
But you meant a class D amp rated at 1500 rms correct?
The car audio world doesn't seem to mingle well with the HIFI world.
The "indestructible trunk thumper" subs are awful impressive but compliance and mass make them hard to drive outside the 12vdc unlimited amps environment. (not unlimited but you know what I mean)
I'd also been looking at all the class T amps so cheaply available now but need to read some threads on how or IF tube preamps fit in that equation.
Class T is totally new to me.
That would be for driving higher sensitivity woofers, not this beast.
EDIT, I don't wanna talk about class T, just saying that I'm looking into all the possibilities.
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Yeah, I mean 1500w or greater. If by 4+4 ohm you mean two 4 ohm speakers, that makes it easier - use a 2x750w amp tied to the same signal.
Does "Class T" still exist as current production parts? I thought that was mostly just marketing-speak by Tripath, and 100% of Tripath parts were discontinued after their acquisition by, iirc, Cirrus. There are still 'new' chips on the market, but they are copies of copies of copies, and as a result their sound quality and durability fall short of the genuine, long-out-of-production article.
At any rate, "class D" is really just a matter of building amplifiers using techniques similar to switching power supplies (rather than techniques similar to linear power supplies). It's not really "digital" (though power DACs exist). "Class T" was just "class D" plus Tripath's special sauce. Which did sound pretty good.
The attached graph is entirely representative of the distortion you should expect from any class-D (or T) amplifier. This one in particular is for International Rectifier's reference design, bridgeable "up to" 1000w RMS into 8 ohms. As you can see, it's real good up until about 400w. And this is into a resistive load, which means that this graph is extremely optimistic.
You'll see the same kind of hockey stick (or no thd vs. power graph at all) in any class-D datasheet. For example, the 20-ish watt rated TA2021 from tripath is way clean up to about 7 and a half watts.
The good news is that since we don't listen to sine waves, your actual music power output will rarely be in the right-hand side of the graph.
Does "Class T" still exist as current production parts? I thought that was mostly just marketing-speak by Tripath, and 100% of Tripath parts were discontinued after their acquisition by, iirc, Cirrus. There are still 'new' chips on the market, but they are copies of copies of copies, and as a result their sound quality and durability fall short of the genuine, long-out-of-production article.
At any rate, "class D" is really just a matter of building amplifiers using techniques similar to switching power supplies (rather than techniques similar to linear power supplies). It's not really "digital" (though power DACs exist). "Class T" was just "class D" plus Tripath's special sauce. Which did sound pretty good.
The attached graph is entirely representative of the distortion you should expect from any class-D (or T) amplifier. This one in particular is for International Rectifier's reference design, bridgeable "up to" 1000w RMS into 8 ohms. As you can see, it's real good up until about 400w. And this is into a resistive load, which means that this graph is extremely optimistic.
You'll see the same kind of hockey stick (or no thd vs. power graph at all) in any class-D datasheet. For example, the 20-ish watt rated TA2021 from tripath is way clean up to about 7 and a half watts.
The good news is that since we don't listen to sine waves, your actual music power output will rarely be in the right-hand side of the graph.
Attachments
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"Obviously there is some range between 10lbs-400lbs but the weights get out of control much sooner than I'd expected."
One needs to include the weight of the power xfmr, inductors and chassis, besides the OT. A bass amp may tend a bit toward the heavy side besides.
That GU-81 Amp took 441 lbs for 1200 Watts, or about 2.72 Watts per pound. One can obviously do better weight-wise if that is a priority. That VTA M-125 Amp hit 34 lbs for 125 Watts, or 3.6 Watts per pound. It looks rather light in the inductor dept. though.
A switchmode power supply could shave off maybe 40% of the weight. And an OTL design might trim off another 20%. (more tubes and filament/heater power required though) (the OT for the tube amp in this case looks more like a current transformer, around 0.2 Ohm output Z instead of 8 Ohm)
--------------------------------
Another approach would be to start with a SS amplifier, and modify it to give tube sound. The attached diagram just replaces the global feedback attenuator of a SS amplifier with a triode in reverse. This means the output must equal the input signal times the tube Mu. (don't pull the tube out while its working though)
--------------------------------
And a half way approach uses a tube amp to put the finishing touch onto the output of a SS amp. A Tube Veneer Amp so to speak. (2nd diagram) (the output xfmr for the tube amp looks more like a current transformer in this case, like 0.2 Ohm output Z, instead of 8 Ohm)
One needs to include the weight of the power xfmr, inductors and chassis, besides the OT. A bass amp may tend a bit toward the heavy side besides.
That GU-81 Amp took 441 lbs for 1200 Watts, or about 2.72 Watts per pound. One can obviously do better weight-wise if that is a priority. That VTA M-125 Amp hit 34 lbs for 125 Watts, or 3.6 Watts per pound. It looks rather light in the inductor dept. though.
A switchmode power supply could shave off maybe 40% of the weight. And an OTL design might trim off another 20%. (more tubes and filament/heater power required though) (the OT for the tube amp in this case looks more like a current transformer, around 0.2 Ohm output Z instead of 8 Ohm)
--------------------------------
Another approach would be to start with a SS amplifier, and modify it to give tube sound. The attached diagram just replaces the global feedback attenuator of a SS amplifier with a triode in reverse. This means the output must equal the input signal times the tube Mu. (don't pull the tube out while its working though)
--------------------------------
And a half way approach uses a tube amp to put the finishing touch onto the output of a SS amp. A Tube Veneer Amp so to speak. (2nd diagram) (the output xfmr for the tube amp looks more like a current transformer in this case, like 0.2 Ohm output Z, instead of 8 Ohm)
Attachments
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Woops, a typo got fixed in the wrong place above.
Delete the last enclosed sentence, just above the first dashed line in previous post.
Delete the last enclosed sentence, just above the first dashed line in previous post.
Yeah I did mean chip amps.
Some subwoofers have gone to dual voice coils with various impedance.
They can be run series or parallel. On this speaker possible configs are parallel for 2ohm, individually on two different 4 ohm channels, series for 8 ohms. (allowing bridging most 2ch amps)
We are having a storm so I'm able to do a full volume test. (as if)
I did just connect it to a Samson S1000 ( admittedly low brow but the only thing I'm willing to do potentially destructive testing with today ; )
a single 4ohm coil rated at 250w rms was able to take the entire output, supposedly 500x2 when bridged into 4 ohm. (they lie)
Over 3/4 volume it began to distort and clipping fairly hard at full volume and running quite hot.
That is a single coil 😀
Your x3 estimate sounds about right.
good subwoofer test https://www.youtube.com/watch?v=6HRac9vyKJE
punishment for your amp https://www.youtube.com/watch?v=Z6hGiY10bcI
`
We should consider this thread over. I didn't realize 500w was out of the realms of sanity. I'm going to read in the transistor amp section for a while.
Some subwoofers have gone to dual voice coils with various impedance.
They can be run series or parallel. On this speaker possible configs are parallel for 2ohm, individually on two different 4 ohm channels, series for 8 ohms. (allowing bridging most 2ch amps)
We are having a storm so I'm able to do a full volume test. (as if)
I did just connect it to a Samson S1000 ( admittedly low brow but the only thing I'm willing to do potentially destructive testing with today ; )
a single 4ohm coil rated at 250w rms was able to take the entire output, supposedly 500x2 when bridged into 4 ohm. (they lie)
Over 3/4 volume it began to distort and clipping fairly hard at full volume and running quite hot.
That is a single coil 😀
Your x3 estimate sounds about right.
good subwoofer test https://www.youtube.com/watch?v=6HRac9vyKJE
punishment for your amp https://www.youtube.com/watch?v=Z6hGiY10bcI
`
We should consider this thread over. I didn't realize 500w was out of the realms of sanity. I'm going to read in the transistor amp section for a while.
And a special thanks to Mr. Smoking amp for adding so much info. I AM reading it, it's a lot to digest at once.
This project is going to take some time to plan......
This project is going to take some time to plan......
I have been down that road.....think about what tubes were in the organ.....a big batch of twin triodes, In the old Baldwin that I parted out there were 36 X 6SN7's (that's what I wanted from it), and a few other small tubes. Each one of those 6SN7's needs 600 mA just to light it's heater, but only one or two mA for the flip flop frequency divider. So the huge power transformer had two FAT green wires which made 6.3 volts at over 20 AMPS!!!! but less than 100 mA of B+ current. The huge transformer is probably not useful for an amplifier.
A 500 watt tube amp IS doable, but not by a beginner that hasn't built a tube amp before. I have been building tube amps for over 50 years, and I haven't made my 500 WPC amp yet.....but it will be built. The cheapest way to make a high quality full frequency range amp is to run about 650 volts into 4 BIG sweep tubes, or 6 or 8 smaller tubes PER CHANNEL. The OPT's will be about 20 pounds each, and cost about $400 EACH!!! Power can come from a few Antek or other toroids. I already have all the parts, but too many more useful projects on the table.....OH, yeah I haven't even finished building the table.
You can get similar power with high voltage transmitting tubes, but the impedance goes up, and the OPT's get even more expensive.
Below about 600 volts the impedance gets low enough that a large number of tubes will be required to support the peak currents.
Settle for 100 WPC, build Pete's big red board with 6HJ5's get 125 WPC, over a dozen have been built, not terribly hard to build. Want to use it to drive a sub? I'm not sure the 100 watt Edcor OPT's will stand up to constant thumps of 25 Hz bass without saturating. When an OPT saturates often, things blow up because the tubes have to eat all the overcurrent.
Cheap sub amp....buy one of the Chinese "500 watt" class D boards that use the TI TAS 5630 chip. I got a $50 board almost 2 years ago. I haven't blown it up yet, and it does make over 300 watts on a 600 watt 48 volt power supply (from Amazon). Make the tube amp to play everything above 100 Hz.
I've seen Mr. Millet's ebay offerings. Very nice to have things all laid out and reasonably priced.
I got into organs FIRSTLY for the purpose of playing them, secondly for the 12AX7s and 12" alnico speakers.
All the rest are just a bonus and eventually I started thinking about guitar amps (cherryburst? really?)
I didn't really expect to make anything with the mondo transformers from tube oscillators organs.
Most of what I'm after are tonewheels with a tube amp. These have a fairly balanced set of transformers because it's all in the amp.
I'll be going Sunday to get another L100... free. (maybe $12 in gas and some beer for the second man)
Not a bad deal, even before counting speakers and iron.
As a side note all the hammond tube amps have a RCA phono input (left side of the big silver box) and sound quite nice in combination with transistor amps and ceramic magnet speakers.
Unfortunately their age is a handicap. (EDIT this is AO-29 of which I have 3 currently, L100 uses AO-41 +AO-43)
I got into organs FIRSTLY for the purpose of playing them, secondly for the 12AX7s and 12" alnico speakers.
All the rest are just a bonus and eventually I started thinking about guitar amps (cherryburst? really?)
I didn't really expect to make anything with the mondo transformers from tube oscillators organs.
Most of what I'm after are tonewheels with a tube amp. These have a fairly balanced set of transformers because it's all in the amp.
I'll be going Sunday to get another L100... free. (maybe $12 in gas and some beer for the second man)
Not a bad deal, even before counting speakers and iron.
As a side note all the hammond tube amps have a RCA phono input (left side of the big silver box) and sound quite nice in combination with transistor amps and ceramic magnet speakers.
Unfortunately their age is a handicap. (EDIT this is AO-29 of which I have 3 currently, L100 uses AO-41 +AO-43)
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At Amplifiers with valves the first part there is a 2 x 600 watt or 1 x 1200 watt tube amplifier.
Then at part EL64xx ther is a 750 watt tube ampllfier (EL6470); EL6471 = 1000 watts; EL6472 = 2000 watts EL6477 anr EL6478 (10KW and 20KW)
the EL6480; EL6481 and EL6482 are 50 Kw = 150-200 Kw amplifiers.
alle wil=th valves 🙂
Enjoi!
Then at part EL64xx ther is a 750 watt tube ampllfier (EL6470); EL6471 = 1000 watts; EL6472 = 2000 watts EL6477 anr EL6478 (10KW and 20KW)
the EL6480; EL6481 and EL6482 are 50 Kw = 150-200 Kw amplifiers.
alle wil=th valves 🙂
Enjoi!
Thank you Mississippi!
Those parallel amps are fascinating but I wonder how load impedance is dealt with.
Doesn't paralleling 2 amps halve the load impedance? Then 3 amps?
I don't see multiple jacks so how is this dealt with? (or am I completely wrong)
I do like that idea very much considering efficiency.
It would also work nicely with smaller components, er, more easily sourced components.
Shopping now for 6P31S, 6CM5, 6JH5, all $5 or less each. Basically cheap enough to offset the cost of iron (and spare up
)
Back to work for me now ... no rest for the wicked.....
Those parallel amps are fascinating but I wonder how load impedance is dealt with.
Doesn't paralleling 2 amps halve the load impedance? Then 3 amps?
I don't see multiple jacks so how is this dealt with? (or am I completely wrong)
I do like that idea very much considering efficiency.
It would also work nicely with smaller components, er, more easily sourced components.
Shopping now for 6P31S, 6CM5, 6JH5, all $5 or less each. Basically cheap enough to offset the cost of iron (and spare up
)Back to work for me now ... no rest for the wicked.....
Because there is no feedback, each amp is a voltage source.
The outputvoltages are the same, the current can be added.
All outputs of the output transformers are connected in parallel when switched on.
Each amp will be responsible for a part of the load. It's a "constant voltage output" system.
The outputvoltages are the same, the current can be added.
All outputs of the output transformers are connected in parallel when switched on.
Each amp will be responsible for a part of the load. It's a "constant voltage output" system.
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