kevin gilmore

first grilling of the new year. prime tomahawk

i have never seen a transformer output amplifier ever generate thd numbers like that. Not a single one regardless of cost. not even the lundhall silver thing thats $5k each. can't wait to see what a 10khz square wave looks like. also likely that its not actually a balanced amplifier even though it has balanced inputs. i think that kingsound made a chipamp/transformer portable. never heard anyone that liked it.

so birgir bought a a90d without knowing it. nice.

they quote .0008% thd has to be koss circuit. opamp driving stack of transistors. lots of gain and lots of feedback. no chip amp driving a transformer can do this. and nothing else can do 2000 vppss also remember they are doing this on a total power budget of 15 watts.

well its much better built than the viva piece of crap.

the idea is to make the environment for the stupidly expensive tubes as friendly as possible. there are rumors of 300b in one or more amplifier companies with an average tube life of 8 months. For something that should be 10,000 hour tubes. my circuit limits the start current to 1.5 amps for 30 seconds.

no output transformers on the other side. Products (vivaaudio.com) looks to be a phase splitter output similar to the beveridge speaker. balanced from a single ended input. what a massive piece of crap this is.

is that supposed to be a choke load for the 300b? whats with the extra shunt rc filters?

was saving that for the xxl version ok, fine

fixed. glad someone is paying attention.

yep, a trim pin. not really necessary unless someone comes up with a reason. all parts on order.

had to make the board bigger because of the diameter of the 300B pictures not same size (major squares are 1 inch)

that section runs on 300 volts. ksa1156 is in stock at mouser now. would work fine. i think the pinout is backwards from 2sa1968 so just rotate it around. the emission labs tube with the octal base and the center tap filament would make things much easier but would limit the amp to those tubes. so its the standard 4 pin socket.

so i posted this elsewhere because people really want to spend large amounts of money on an electrostatic amplifier that uses a pile of 300b. this is the first of two. Megatron xl with 4 x 300b Megatron xxl with 8 x 300b Power supply #1 goldenreferencehv all solid state Power supply #2 tube rectified lc filtered no regulation solid state regulated bias. Power supply #3 tube rectified lc filtered 4 x 6l6gc fully regulated voltages. 300 volt tube rectified and 6bq5 regulated power supply. solid state regulated bias high voltage rectifier tubes are gz34 (5ar4) 300v rectifier tube is ez81 I figure a megatronxxl with power supply #3 should come in at a retail built price of $40k evidently one or more companies are making dc supplies that slam 7 amps into cold 300b resulting in tubes that don't last very long. so this will have a slow start quad 5v power supply board. the xxl will have 2 of these boards. amp chassis will be about 14 x 14 x 4 inches. power supply box should be the same size. the spice simulations indicate that minimum distortion is set at about 33ma, so this is likely to eat about 300 watts total power consumption. distortion will end up about .01% at full voltage swing.

buy whatever you can find that is the right voltage and meets minimum current requirements. bonus if it fits the original holes. otherwise remove old studs, drill new holes etc..

use something round and small diameter to push the piston down, then tiny long nose pliers to extract the o-ring. then size appropriately from a selection of o-rings and reassemble the same way.

pics of the unreplaceable o-ring please.

the owners of ray samuels audio will say their amp is the best. just ask them. my favorites are 1) rudistor with the silver wire enhancement 2) singlepower es2 with the all tube regulated power supply 3) felista megatron. definitely you are a moron. torus? you mean tuchas. and you must have a really big one.

100 watts maximum for those speakers!

there is (or at least should be) a board for the rk27 pot.

you may be the first person to test these boards. but if you have music, highly likely that everything works right. if the dac has a significant dc offset, that may cause trouble. maybe wiring of the pot is wrong? edit: 10k pot highly recommended with the that340 chips. 50k is not going to perform well.

so that is what new math actually is.

a short in that place is definitely going to cause trouble.

i thought the viva was all about bling.

the pictures show that the inputs are line level. and its tubes. so likely push pull transformer output. for the price, can't touch it.