Hello all, for anyone interested here is a description of the technical side of these massive amps.
I'll start with the chassis, it is made entirely of 1/2" aluminum and 1/2" tool plate for the top and bottom. All aluminum is 6061-T6. Everything was done using a Bridgeport manual mill, as these plates are too large for the average sized CNC machine. All machine work was done by myself with the exception of the "W"'s.
Those were cut with water jet. The finish as you can see is either chrome or blue metallic powder coat base coat covered with a high gloss powder coat. It is very blue and shiny! It has so much silver flake in it that in really bright light they tend to look silver, very cooool!
The inside of the amps look exactly like the outside! All of the transformr and capacitor cans are deep drawn aluminum and have no seams, very costly but worth every penny. Cost was not in the picture on these amps. Top notch parts thruout.
Now, the reason they are so large. Danny wanted them to be extremely powerful, have huge amounts of headroom, and he wanted this to be acomplished with a very wide bandwidth and at power!!
I put many hours of thought into this project and this is what I have achieved.
I'll start off with the topology. The amps are parallel push-pull UL operation class a/b. Each channel uses a matched sextet of KT-88's and 3 GE7044's. The amps have only 3 caps in the entire audio path and they are all Sonicap Platinums
The output stage is direct coupled NO CAPS! All resistors are either PRP or KIWAME for the higher wattage units.
This is what I measured on the original prototypes:
280 watts continuous into either 4 or 8 ohms
I measured the bandwidth at full power(280 watts) and this is what I got:
4hz- 70khz!!!!
and the thd at this level was <2%!!!!
I measured this several times because I did not believe it myself!
I designed the output transformer for these amps as I do for all my stuff, well it is a monster
Weighing in at 60 pounds in the raw!! aa The reason for the wide bandwidth. These weigh more than alot of amps.
The bias is user adjustable and is indicated by the use of 2 large meters that read all of the time.
With the bias current I selcted to use with these amps They will output approximately 110 watts in class A. The tubes will last around 3 years depending on the amount of use.
It takes a massive power supply to get all of this going.
I started with a 40 pound power transformer that supplies all of the voltages needed except the filaments, those are separate transformers, 3 of them. The frontend and bias supplies are pretty straight forward, all 3 supplies are pi filtered and have huge amounts of capacitance and each cap is bypassed with a Sonicap.
The main B+ supply is the beast. It is a dual pi filtered supply. I designed some 2hy 1 amp chokes that have a dcr of 5 ohms. Each supply uses 2 of these. the rectifiers are ultrafast soft recovery types. The capacitor banks consist of 6- 2700uf@450 volt cans, each one of these is bypassed with a Solen metalized poly 47uf@630volt cap and these were each bypassed with a Sonicap Platinum 1 uf@600volt. Very expensive caps!
The main B+ runs at 650 volts and can output 1 amp easily! The cap banks have 915 joules of energy storage@ 650 volts!!!!
Very Very dangerous! Headroom, I think so!
Thats about it. I'm sure Danny will post more pics as I get them to him. I'm hoping to be finished at the end of this week and I'll start to test them. By the time I'm finished I will have around 5-600 hours of time in them from idea to finished. I just wish I didn't have to be building them on my living room floor because they are huge and man are they heavy. Around 260- 275 when fully finished each amp! Enjoy
Gary
