Á'la Krell (if you remember those commercials from the 80'-s)
55Vac x 1.41 = 77.5VDC
77Vdc rails will allow about 500W @ 4R (more or less!)
If you want to make a decent amplifier I would go for dual mono amp with 1 transformer per channel.
For instance my Rauch DVT250s lateral mosfet amp has 2 X 1KVA transformers and is rated at 550W@4R per channel, but the transformer voltage is a little higher.
77Vdc rails will allow about 500W @ 4R (more or less!)
If you want to make a decent amplifier I would go for dual mono amp with 1 transformer per channel.
For instance my Rauch DVT250s lateral mosfet amp has 2 X 1KVA transformers and is rated at 550W@4R per channel, but the transformer voltage is a little higher.
I have a bad feeling about your project, Daniel. I could be wrong, but I guess that you do not have a lot of experience building amplifiers. First, your transformers are not 1000W, but 1000Volt-Amps, which are different from watts. Second, two 1000VA transformers are overkill for any home audio application. Third, if you had the experience necessary to tackle such a big project, you would know the answer to your questions.
If you want to take full advantage of the transformers, you will need a very high power design with a lot of filter capacitors, many output devices, a softstart, huge heatsinks, and a huge chassis to put it all in. In fact, I don't know if you will be able to find a chassis that holds two 1000VA transformers and all the other stuff you will need. This will get very expensive very fast. If you bought the transformers because you got a good deal on them, you will waste far more money on heatsinks and filter capacitors than you "saved" on the transformers.
My advice is:
1) Decide how much money you're willing to spend.
2) Pick a design that looks interesting and fun to build, like maybe the F5 or Honey Badger for sale at the diyAudio store, or the LM3886 kit from ChipAmp.com. There are always group buys going on for F5 parts. Pick something that many other people are building. It's more fun that way.
3) Try to predict how much it's going to cost. Be as detailed as you can. All the little things (PCB standoffs, RCA phono jacks, power input module, fuseholders, barrier strips) add up quickly.
4) Try to return your 1000VA transformers for the stuff you'll need for your new amplifier. I hope the store sells a lot of different stuff.
5) Tell us what you are going to build. Have fun!
If you want to take full advantage of the transformers, you will need a very high power design with a lot of filter capacitors, many output devices, a softstart, huge heatsinks, and a huge chassis to put it all in. In fact, I don't know if you will be able to find a chassis that holds two 1000VA transformers and all the other stuff you will need. This will get very expensive very fast. If you bought the transformers because you got a good deal on them, you will waste far more money on heatsinks and filter capacitors than you "saved" on the transformers.
My advice is:
1) Decide how much money you're willing to spend.
2) Pick a design that looks interesting and fun to build, like maybe the F5 or Honey Badger for sale at the diyAudio store, or the LM3886 kit from ChipAmp.com. There are always group buys going on for F5 parts. Pick something that many other people are building. It's more fun that way.
3) Try to predict how much it's going to cost. Be as detailed as you can. All the little things (PCB standoffs, RCA phono jacks, power input module, fuseholders, barrier strips) add up quickly.
4) Try to return your 1000VA transformers for the stuff you'll need for your new amplifier. I hope the store sells a lot of different stuff.
5) Tell us what you are going to build. Have fun!
What speakers do you have that will take 38 V rms on them? Are you a guitar or bass player? You can get that out of 110 VAC transformers. (stacking the windings to make a center tap). Pretty high voltage for hi-fi use, unless you are pumping Beethoven into a 300 seat restaurant. And like Byron said, you're limited to about 1.5 A per output transistor by life, transistors, and heat sinks, so you have a lot of parallel output transistors on a big heat sink behind a big fan to use this high a voltage unless you were intending to drive 16 ohm guitar speakers. The high a voltage is PA use or guitar or bass use only, IMHO. PA amps have 2 levels of drivers transistors, 4 bias diodes, VI limiters, SOA detectors, all sorts of complications for a newbie. Look at the Peavey CS800 b revision schematic, about as simple a PA amp as you can build with +-80 v rails. And the B revision is not hifi. (Schematic is on diyaudio.com use google to search diyaudio.com:CS800 schematic or something).
The exception is if you have lot of obsolete gain 10 output transistors like 2n3442 or 2n3773 or something. In the late sixties the excess voltage of 77 v rails was used to put out 22 V on 8 ohm speakers, but that didn't last past 1980. Motorola started pumping out high gain G suffix output transistor then, for more than 1/3 of the rail voltage on the speaker.
I'm building an amp with a bargain 95 VAC CT transformer, but I'm only using one side of the transformer, with one pair of output transistors. I'm only looking for about 35 W into an 8 ohm speaker. The other half of the transformer ? If it can figure out how to couple a second signal to the minus rail instead of the center tap, the bottom half of the transformer might be the second channel for the second speaker.
The exception is if you have lot of obsolete gain 10 output transistors like 2n3442 or 2n3773 or something. In the late sixties the excess voltage of 77 v rails was used to put out 22 V on 8 ohm speakers, but that didn't last past 1980. Motorola started pumping out high gain G suffix output transistor then, for more than 1/3 of the rail voltage on the speaker.
I'm building an amp with a bargain 95 VAC CT transformer, but I'm only using one side of the transformer, with one pair of output transistors. I'm only looking for about 35 W into an 8 ohm speaker. The other half of the transformer ? If it can figure out how to couple a second signal to the minus rail instead of the center tap, the bottom half of the transformer might be the second channel for the second speaker.
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Two words: Dirty Harry. It's a stripped-down high(ish)-fi version of the CS800, and about as easy to get working as something in this power range gets.
Since you have two trafos you could actually clone a QSC USA1310, which requires separate power supplies for each channel. Dirt simple schematic and low component count. Doesn't quite sound as good as the DH, though.
Since you have two trafos you could actually clone a QSC USA1310, which requires separate power supplies for each channel. Dirt simple schematic and low component count. Doesn't quite sound as good as the DH, though.
Use both halves and a 2-diode rectifier (pointing the same way). Center tap is GND. Regulation will be better this way. This is how they used to do simple single power supplies back when amps like Apex's new retro design were common.
(2x55V-AC) power 1000VA this is write on the transformer , output current is 9.09 A 
Each they are weigh 7.3 kg
ByronInLawrence i have expirience my friend , don't worry about me I was just interesting what the others gonna say and to see maybe others gonna give me better choise then my choice ..
Edit: I think that i found good amplifier documentation
http://www.construyasuvideorockola.com/downloads/amp400w_mono.pdf
I made one time amplifier from this columbian page , it was working good , i think to make this amplifier , it has all the documentation , pcb , how to wire the amplifier , list of all components that i need , everything
At the bottom of this documentation it is write : If you want more power, use MJL21194 transistors, the voltage should rise
voltage transformer to a maximum of 60 +60 volts AC.
Can i use 1000 VA , 2x59V AC, 8,48 A toroidal transformer with MJL21194 transistors on the output to get more power ? does it safe ? And how much RMS power im gonna get on 4 ohm-s with this configuration and how much RMS power on 4 ohm-s with the standard transistors and standard transformer 2x55V-AC power 1000VA ? Some word for the THD for the two configuration ?
Edit: Video with amplifier which i was talking about http://www.youtube.com/watch?v=pgzdrWy6APA
I thnk that all have now something to say
Thank to all , Daniel
Each they are weigh 7.3 kg ByronInLawrence i have expirience my friend , don't worry about me
I was just interesting what the others gonna say and to see maybe others gonna give me better choise then my choice .. Edit: I think that i found good amplifier documentation
http://www.construyasuvideorockola.com/downloads/amp400w_mono.pdf
I made one time amplifier from this columbian page , it was working good , i think to make this amplifier , it has all the documentation , pcb , how to wire the amplifier , list of all components that i need , everything
At the bottom of this documentation it is write : If you want more power, use MJL21194 transistors, the voltage should rise
voltage transformer to a maximum of 60 +60 volts AC.
Can i use 1000 VA , 2x59V AC, 8,48 A toroidal transformer with MJL21194 transistors on the output to get more power ? does it safe ?
And how much RMS power im gonna get on 4 ohm-s with this configuration and how much RMS power on 4 ohm-s with the standard transistors and standard transformer 2x55V-AC power 1000VA ? Some word for the THD for the two configuration ? Edit: Video with amplifier which i was talking about
http://www.youtube.com/watch?v=pgzdrWy6APAI thnk that all have now something to say
Thank to all , Daniel
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Wire it for 220 Volts and then plug it into 110 volts
then you gonna have 27.5 Volts AC plus 27.5 Volts AC with 500 watts of power.
Other obvious use is to make a very power full unit as you may have almost 80 plus 80 volts (aprox.) after rectification and filtering.
Your 1000 watts, if feeding a Class AB audio amplifier, will result in 650 watts RMS of total power.... very nice power.
This will result, after rectification and filtering 38.7 plus 38.7 Volts DC...good to several good amplifier we have in our forum.
regards,
Carlos
then you gonna have 27.5 Volts AC plus 27.5 Volts AC with 500 watts of power.
Other obvious use is to make a very power full unit as you may have almost 80 plus 80 volts (aprox.) after rectification and filtering.
Your 1000 watts, if feeding a Class AB audio amplifier, will result in 650 watts RMS of total power.... very nice power.
This will result, after rectification and filtering 38.7 plus 38.7 Volts DC...good to several good amplifier we have in our forum.
regards,
Carlos
The man who sell me the transformers , say that i can change
maybe ask yourself, do you want good sound, or high power
you need to be both experienced and clever to combine the two
you may be loosing it already at 100watt
That is my question .. What amplifier can i make from two 2x55VAC 1000W toroidal transformers ? What is the maximum power but with the smallest distorsion ...
Regards , Daniel
55VAC -> 55Vrms@1000W -> 55Vrails -> 55V/sqrt(2) = 38Vrms -> sqr(38V)/8ohm=180Watt rms; 4ohm->361watt; 2ohm->722watt.
Maybe you have some more volts due to caps, but don't count on that while having big loads.
Please assume 40% lost due to heat dissipation: 1000W -> 600W for load. ->300W for load per channel.
Max. 300W/channel is the limit.
Vulgo: More power needs more volts or lower ohms (incl. more transformer watts).
Result: 1000W transformers
8 ohm: max. 2x180W
4 ohm: max. 2x300W
2 ohm: max. 2x300W
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do you maybe want to take thet calculation one more time? it's a HUGE misstake in there.
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