thebes Posted July 20, 2014 Share Posted July 20, 2014 (edited) OK Class, Put those aprons on, sprinkle a little flour on your rolling board and pay close attention to the following recipe. First, acquire an old Pilot console for $10 bucks and strip out the transformer. Then head over to your local Kmart and buy this wonderful Made In USA all-aluminum cake pan for $12 on sale. Then contact the esteemed world renowned local chef, TubeFanatic, for some suggestions on a cake filling. cakaeamppowersupplyschematic.pdf cakeampnew-rc-filter-2.pdf Edited July 20, 2014 by thebes Quote Link to comment Share on other sites More sharing options...
thebes Posted July 20, 2014 Author Share Posted July 20, 2014 Now purchase all the labelled ingredients from TubeFanatic's Pdf recipe and pour into the cakepan. Then arrange in the order outlined in his recipe while assuring that any negative waves produced when the amp is cooked will travel all in one direction. Quote Link to comment Share on other sites More sharing options...
thebes Posted July 20, 2014 Author Share Posted July 20, 2014 (edited) Oh boyoboyoboy! Fresh out of the oven and hooked up. Get ready for that wonderful home cooked aroma. Uh oh, it smells kinda burnt, and what's that sound coming from it. Sounds like a 1950's Evenirude 2 stroke boat motor. Better rearrange things and put it back into the oven. Nope still no luck. Repeat, Nope-a-dope. Try again. Net even. Surrender and sent to Tube Fanatic? Yes A few days later a package arrives. Open it up, ah, the smell of freshly baked goodness wafts out of the box. Yummy, can't wait to try a slice. Heaven, Nirvosa and the texture! Balanced throughout the gustatory spectrum. Yummy, Yummy, Yummy. Edited July 20, 2014 by thebes Quote Link to comment Share on other sites More sharing options...
thebes Posted July 20, 2014 Author Share Posted July 20, 2014 Oh almost forgot, sometimes a cakepan needs a little paint to show off what's inside. Quote Link to comment Share on other sites More sharing options...
Lemon string Posted July 20, 2014 Share Posted July 20, 2014 great thread, thanks! Quote Link to comment Share on other sites More sharing options...
The Dude Posted July 20, 2014 Share Posted July 20, 2014 Very nice Marty, did Tube Fanatic explain what the problem was. Would be nice to know if some one decided to build and they ran into the same problem. Now you need to head over to coffee and cables to have a cup of coffee with that cake, and some low cost nicely shielded cables you enjoy so much. Quote Link to comment Share on other sites More sharing options...
thebes Posted July 20, 2014 Author Share Posted July 20, 2014 (edited) OK now to the particulars. Our own Maynard (TubeFanatic), yet another one of the Forum technical team to run afoul of my desire to play around with dangerous voltages, was kind enough to lend his design talents and patience to my efforts to recast the guts of a tired old Pilot console into into a standalone Single Ended Pentode amp. What he came up with was a design for an integrated amp. After various misadventures on my part, and approximately 476 emails to a very understanding TubeFanatic, I had managed to construct an amp that sounded truly wonderful with only one fatal flaw. It putted along like a motorboat. After numerous attempts I surrendered and like a blushing bride sent my creation off to be admired by by a true expert in tube design, where I was sure he would slightly change in the position of a resistor, solve the problem and send me a laudatory email on my brilliant work to my preening delight. Er, uh, he was very kind about it, ("oh Marty, I just made a change or two") but as you can see by the pics he completely rebuilt the entire thing. Then he ran it in for 25 hours, brought it to a musician friends house who owns Cornwall,s the speaker I would be playing this amp through. The two of them put their talents to assuring that it was "voiced" right and sent it back to me. The sound? Absolutely enchanting. Coherent across the spectrum. Wonderful sound stage and depth and detail to die for. The power output. According to Maynard, who used math an things like that to come up with the figure, maybe a half a watt. Shortcomings. Because of the ridiculously low power output, it's better as a linestage amp where it's good in a near listening field to well above 90bd. With vinyl through a preamp tape out it can't drive a LOMC, even with the high gain setting on my Anthem PRE1. What I have worked out, however, if running the amp with the gain on the amp set to about 12 o'clock, I set my preamp gain between 9 and 10, and a Ortofon head amp to boost the LOMC signal for vinyl. For Line playback through the preamp , I use an internal boost of 17bd. This gives me plenty of top end without overdriving what we've taken to calling the "Cakeamp" I've had this in my system for several week now, and I must say this is probably the finest sounding piece of gear I own. It's also been a wonderful learning experience. I'm finally getting a true handle on following a schematic, recognizing the terminology, finally understanding "star" grounding and the concept of grounding in general. Last, but not least, with "after" example of Maynard's work to study, I do believe my next project will have have much better layout and soldering. Thanks Maynard. Yet another prince among all the fine tech types here (Mike BSe and Craig especially) who have been so kind and unstinting in their patience and help to me over the years. Edited July 20, 2014 by thebes Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 20, 2014 Share Posted July 20, 2014 Thebes, I am very proud of you!!! The cake pan was an awesome idea! Really cool! Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted July 20, 2014 Share Posted July 20, 2014 Nice amp! Quote Link to comment Share on other sites More sharing options...
Guest David H Posted July 20, 2014 Share Posted July 20, 2014 Looks like fun. Props to Maynard for the assist. Nice... Dave Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted July 20, 2014 Share Posted July 20, 2014 Thebes.......glad to see you survived another amp project.. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted July 20, 2014 Share Posted July 20, 2014 Good job, Marty. What's the next amplifier project? Quote Link to comment Share on other sites More sharing options...
jason str Posted July 20, 2014 Share Posted July 20, 2014 Even the frosting looks nice. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted July 20, 2014 Share Posted July 20, 2014 Marty, glad that the amp continues to provide so much enjoyment! To clarify a few points for those who are interested: The schematics shown above are for the original proposed design. When I had it here on the bench, I made a number of modifications, so if anyone is interested in building a clone of this, get in touch with me for the updated, final version (I'll try to draw out the schematics this week). Regarding the motorboating, it was caused by a combination of lead lengths which were a bit longer than necessary, the lead dress, and a voltage amp with too much gain. With shorter lead runs, and reducing the gain of the front end by using some current feedback, all was well and totally stable. Power output is actually a bit higher than Marty stated. The limiting factor is the bottom end output due to the smallish transformers, but the unit still put out 1 watt at around 40 Hz before clipping. With the CWs that can still provide a fairly substantial listening level. The 6GW8s (ECL86) which are used are fairly costly these days, so from the standpoint of expense, it would be more effective to use different tubes unless one wants the convenience of using a voltage amp/power amp in one envelope. I really love the cake pan construction. That was an extremely popular mode in the 50s and even in the 60s as the pans were less expensive than actual chassis. Maynard Quote Link to comment Share on other sites More sharing options...
thebes Posted July 20, 2014 Author Share Posted July 20, 2014 Very nice Marty, did Tube Fanatic explain what the problem was. Would be nice to know if some one decided to build and they ran into the same problem. I tried to pin him down on that, but I suspect it was pretty much everything I did, instead of one thing in particular. I mean just take a close look at the Marty build versus the pro build. I have a ways to go. Thanks Craig, Actually I thought I was being original when I bought the cake pan, but it appears that back in olden times hobbyists would build them out of all sorts of things, cake pans, cookie containers, what ever was handy and cheap. As to a future build, I have one or two ideas in mind. As far as a case goes, I do like the looks of this one gallon can I have on hand. Oh, and a note on the case. It doesn't show in the finish cakeamp pic, but I have built a small wooden frame for it, but will do something more substantial. I'm waiting for a customer of mine, whose a major creative woodworker, to get back in town from a consulting job. I'll trade him some time and have him run up something better for this amp. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 21, 2014 Share Posted July 21, 2014 Marty, You have acrylic skills....build a chassis out a clear plex and be very anal about wring and parts quality like using some nice turret strips rather then terminal strips... I know its been done before but I think the look it would warm the twins up for some favorable action... The only bad point will be lack of shielding but with amplifiers its not all that important. Find a simple PP console amp for the donor parts. I'll cook up the circuit. But lets make this a winter project when were both twiddling our thumbs. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted July 21, 2014 Share Posted July 21, 2014 I had a few minutes in which to draw out the final version of the amp which Marty is now using. Hopefully, I didn't omit anything! If anyone spots something which doesn't look right, let me know asap!!! Maynard Marty final design.pdf marty new power supply.pdf Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted July 21, 2014 Share Posted July 21, 2014 As to a future build, I have one or two ideas in mind. As far as a case goes, I do like the looks of this one gallon can I have on hand. Building equipment in unusual enclosures is lots of fun. Many of the hams I know do that all the time. Here's one project built in a tuna fish can! http://www.amqrp.org/kits/tt2/ Maynard 2 Quote Link to comment Share on other sites More sharing options...
NOSValves Posted July 21, 2014 Share Posted July 21, 2014 Maynard, That tuna can is awesome! What program are you using to make those schematics? Your fellow local tech.....Craig Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted July 21, 2014 Share Posted July 21, 2014 Maynard, That tuna can is awesome! What program are you using to make those schematics? Your fellow local tech.....Craig Craig, it's the Digikey Schemeit program. It's excellent although the learning curve takes a while since it has a number of peculiarities. But, considering that it's free, it's worth putting up with some hassles particularly since it has all the tube schematic symbols and lets you create custom symbols as well. Keep in mind that anything you create and save on there becomes their property to use as they see fit. No big deal as far as I'm concerned. Check it out as I think you will enjoy it! Regards---- Maynard http://www.youtube.com/watch?v=hSXmNBdyuls Quote Link to comment Share on other sites More sharing options...
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