Thanks.
At this time I have two boards built and operational. The parts for the build photos will all be here by wednesday.
This weekend I did some experiments with a hybrid configuration using the board to drive mosfets. I have succesfully done this in the past, but this time I made some smoke. I didn't have the time to figure out why it fried.
I am posting a picture of my second board. It is seen here being used in a failed hybrid amp experiment. It is built pretty much like the first board except that there is no rectifier tube. There are two 1N5408 diodes where the tube should be. This looks like the best path to chose with 6CW5's due to their high current demands, more than a 5AR4 can make and a 5U4 drops too much voltage.
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For 6BQ5's, EL84's, 7189A's and the Russian equivalents:
Funny you should ask that. There was a box containing a Hammond 372HX delivered today while I was at work. Of course I hooked it up when I got home. I put in some Russian 6P14P tubes (cheap on Ebay) and cranked it up. At idle the B+ is 358 volts and at a fully cliped 18 WPC the B+ is 347 volts. At a more reasonable 15 WPC the B+ is 350 volts and the distortion is 2.2% in one channel and 2.4% in the other. At 10 WPC the distortion is 0.5%. Some 7189A's may be able to handle more B+ than this, but the Russian tubes, some EI 7189A's and several NOS or used 6BQ5's are on the verge of screen or plate glow at continued full power operation, so 350V looks like a good place to go.
I made a deal on the Hammond 372HX, so I used it. A 272HX would probably work OK for less money (in 120 volt countries).
For OPT's I am using some surplus guitar amp OPT's that I bought a bunch of 10 years ago. They work excellent for this amp, so I doubt that I will try anything else. They are "80 watt" (really about 25 watt) 6600 ohm to 4,8, 16 ohm without UL taps. I have taken one apart and found low cost construction with zero interleaving, wound on power transformer cores, but they measure good, and sound better. I have tried the lowest cost Edcor XPP10-8-8K OPT's with mixed results. They sound great at low volume but distort at a few watts or so. After all they are only 10 watt transformers.
I would look for something with a 6K to 8K ohm primary, at least a real 20 watt rating more would be better but too big (over 50 watts) will cost some power and sonic detail.
For 6CW5's:
I am still looking for the optimum power transformer. I will report further as I get to look at more transformers, but I am currently using an Antek 1T200.
For an OPT look for a 3K to 4K ohm primary, and similar ratings to the EL84 transformers. I am using the same guitat amp OPT wirh a 8 ohm load on the 16 ohm tap to give a 3300 ohm primary.
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The board is 5.5 by 8.0 inches.
For $20 each, I'll look at the ugly toroids!
I am in the process of building two amplifiers based on the Simple P-P. One will be a double decker design. The toroids are on the lower deck and will not be visible. The other will simply mount all of the components shown in the last photo on a wood and Lexan chassis. I haven't worked out all of the details yet, but I will post them when I figure it all out.
In theory it should be OK. It might be a good idea to mock up all of the components (on a piece of plywood or your workbench) and carefully test for hum before committing to a chassis design.
The double decker Simple P-P that I started has 3 toroids all touching side to side. One of them is the power transformer. This amp is not finished yet, so I don't know the results. I have wood shop class on thursday nights, and I would have finished it last night, but lifes little roadblocks keep getting in the way.
On another ocassion I stacked the toroids on top of each other with no obvious interaction. They were all power supply transformers though.
The amp testing that I have been doing with this board has been done with a mix of toroid and conventional transformers. They have been randomly scattered on my work surface and I have yet to notice any coupling, but it is possible.
The double decker Simple P-P that I started has 3 toroids all touching side to side. One of them is the power transformer. This amp is not finished yet, so I don't know the results. I have wood shop class on thursday nights, and I would have finished it last night, but lifes little roadblocks keep getting in the way.
On another ocassion I stacked the toroids on top of each other with no obvious interaction. They were all power supply transformers though.
The amp testing that I have been doing with this board has been done with a mix of toroid and conventional transformers. They have been randomly scattered on my work surface and I have yet to notice any coupling, but it is possible.
George,
Are you ready with the installation guide? I am still a bit new at this so I am not ready to run with scissors yet.
I have been holding off on buying the boards until you have this ready to go. Can you give us an update when you have a chance.
Still sending prayers for Sheri's mom.
Alan
Are you ready with the installation guide? I am still a bit new at this so I am not ready to run with scissors yet.
I have been holding off on buying the boards until you have this ready to go. Can you give us an update when you have a chance.Still sending prayers for Sheri's mom.
Alan
There have been many interruptions in my work on the instructions including 50+ hour work weeks and Sherri winding up in the hospital with cardiac symptoms (all tests were clean). I have one board that I have been listening to, and three more being built for photographic purpuses. I will build amps with these boards too. Despite all of the **. I took over 700 pictures last weekend, but I am not finished yet. I will take a few hundred more pictures, then sort through them all to find the ones I like. They must then all be resized and edited for posting to the web. A trip to Sherri's moms must happen soon, but her treatments are on hold until her WBC level improves, when that happens I will be gone for about 10 days. Everything is loaded on my laptop so I can work on the instructions anywhere. Given all of these variables it is real hard to provide an exact date, but I am sitting on over $2000 worth of boards and parts (all on my credit cards), and I have sold exactly 1 board this month, so I am trying to hurry as best I can while still providing an excellent set of instructions.
Here is a photo of the 3 boards currently under construction. Note the diodes in place of the rectifier tube on one board. This is required with 6CW5 tubes. Also note the tube socket on "stilts" on another board. This lets you mount the parts on the top of the board and raise the tubes up to the deck. I used this method on a Tubelab SE with a Lexan deck for show off purposes. Astute observers will notice that in my rush, I put the tall socket on the wrong board. It should be on the board behind the one it is on. Now I get to take it off.
I got to crank the Simple P-P to eleven last night (Sherri wasn't home). It is running cheap Ebay sourced Russian 6P14P tubes, a Hammond 372HX power transformer and some surplus OPT's. The Tubelab SE likes detail and music like Norah and Diana Krall, The Simple SE is a good all around performer, but this amp likes to ROCK. It does justice to Norah and Diana, but it LIKES Pink Floyd, Ozzie, Santana, Metallica, and all sorts of vintage rock. I even enjoyed cranking some Billy Idol. Some of the punch and dynamics that I like so much in my old 300Beast are present in this amp. The only thing this amp has in common with the Beast is the surplus OPT's, could it be the OPT?
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George,
It seems like it in never stops for you and Sherri. I think that I speak for many here on diyAudio.com when I say we are thinking of the two you and wishing you the best, or praying for the two of you. I think that we all appreciate your input and insights regarding your own work, as well as the work of others.
I appreciate the update, and I looking forward to purchasing at least two, of your Simple PP boards. I have been watching the progress of this project since it first appeared on the pages of tubelab.com. i am very excited to get working on the board, and trying it out in a number of variations.
Regards,
Alan
It seems like it in never stops for you and Sherri. I think that I speak for many here on diyAudio.com when I say we are thinking of the two you and wishing you the best, or praying for the two of you. I think that we all appreciate your input and insights regarding your own work, as well as the work of others.
I appreciate the update, and I looking forward to purchasing at least two, of your Simple PP boards. I have been watching the progress of this project since it first appeared on the pages of tubelab.com. i am very excited to get working on the board, and trying it out in a number of variations.
Regards,
Alan
Oh dear,atleast the tests came back okay. Stress can cause such issues (don't ask me how I know).. You guys should take a rest (as much as possible) and don't let us add to it.
I'm very anxious to try out the universal PP driver boards once they're ready,but I can patiently wait until things settle down for you a bit.
Ditto Digitaljunkie's comments. I've got one of the boards ready for parts/stuffing but I have absolutely no problem waiting for the parts list, construction details, etc. Take a break a relax and little George. After all, this is a hobby (spelled FUN), not your job. While we may at times sound like impatient children, the ol' 'good things come to he who waits' definitely applies to your amps. Take you time and give the wife a big hug!
I'm very anxious to try out the universal PP driver boards once they're ready,but I can patiently wait until things settle down for you a bit.
I really meant for my post to come out sounding the same way. I fell short!!! While I am excited, I can wait for as long as it takes. You and Sherri need to be healthy for each other first and foremost. I think, as I said earlier, that we all care more about you than your stuff. Be well and take good care of yourself and your wife.
Alan
I am curious as to the sonic differences for the different power tubes that are compatible with this board. This will be my first tube amp build and I have been looking at EL84 type amps but i am still a newb at this.
I hope to be able to purchase this board as a kit with the part to populate the board and look to everyone else for transformer suggestions.
My plan is to use this amp with some 8 ohm 90db bookshelf speakers as a secondary system with the possibility of a powered sub at a later date.
Thanks,
Scott
I hope to be able to purchase this board as a kit with the part to populate the board and look to everyone else for transformer suggestions.
My plan is to use this amp with some 8 ohm 90db bookshelf speakers as a secondary system with the possibility of a powered sub at a later date.
Thanks,
Scott