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Old 13th February 2013, 06:07 PM   #31
TheGimp is offline TheGimp  United States
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midmoe, to upload photos click the "Go Advanced" button below the message text box.

This will take you to a screen which has a box below for the button to "Attach Files".

This opens a dialogue box which allows you to browse your computer for the file (Photo), upload it, and attach it to your message.
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Old 14th February 2013, 12:14 AM   #32
midmoe is offline midmoe  United States
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Default schematics garnier circletron 9115

still in semi-prototype phase, but good enough to be useful. Am drawing about 130 watts power consumption, tubes running not too hot, very listenable with good volume considering impedance mismatch.
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Old 14th February 2013, 12:58 AM   #33
midmoe is offline midmoe  United States
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thanks to the gimp for the exxcellent info. Somehow the power supply didn't get included, but this is the intresting one anyway. Will work on getting power supply up later, also a short movie. The model number is 115 on the schematic, but numbered 9115 in text. This is because the basic design without output stage is a 115, but the entire amp has 9 tubes, hence the 9115 demarcation. I am planning on building higher tubed units, in stereo, using a similiar sized box, but "candle abra-ing" the output tubes. Instead of a single output tube per socket, an adapter will sit down and have room for 2, 3 or 4 tubes in each candleabra cluster. So the model number will reflect the 115 designation, preceded with the total number of tubes the power supply is designed to carry. A problem developed when I tried to order transformers for a second unit...seems as though the fil. xfmr. is no longer available from Allied, but they had a Hammond equiv. which I went ahead and ordered. Some of the higher tubes sets will be completely wired series string, controlled warmup. This will eliminate the bulky fil. xfmr. and allow room for a bigger power xfmr. for the main B+/B- supplies. After I've made four monos, I should be finished setting up a metal shop, and wood shop and have all the bugs worked out. I'm using 1/2" solid white oak for case sides, but local suppliers have walnut, cherry and ash. I'm using alot of old school parts, such as from 40-50s amps from organs for better quality than what is normally available. along with genuine catalin trim parts I have saved since th 90's midmoe
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Old 15th February 2013, 03:14 PM   #34
midmoe is offline midmoe  United States
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intresting "muntzian" development.....in fooling around with the series string in driver section, I placed the 12AU7 and two 12BH7s in series w/diode rectifier and put in as additional voltage drop a 25Z5 tube from the late 30's. Everything seems to be lighting up in a normal fashion. With a "ballast" tube mounted up on top, the heat will be discarded without having a hot resistor inside case. Of course, any 25 volt .3a tube might do....looking thru the tube manual, I see 25L6, 25N6, 25W4, along with a few others....if I can dig up a 25L6, I'll try it as that uses a standard octal socket. Funny thought...using the 25L6 as a headphone driver output....haha...or could some other 25 volt tube be used in some ancillary bias control circut...?...(dual purposed) or perhaps two 12 volters in series. this would widen the range of options in thinking out some sort of bias control/equalization circutry... madman muntz lives on...midmoe ps.....four sixes??
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Old 15th February 2013, 07:51 PM   #35
Ketje is offline Ketje  Belgium
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Well,finaly a cicuitdrawing
To get a better view I redraw the thing.Can't say I like it Click the image to open in full size.
The screengrids are connected that the tube operate somewhat like a UL-PP with the tap at 50%.The voltage won't go very deep,poor swing not much output.Between the anodes is now 120+150+120+150=540ohm that comes as a load in parallel with the speaker.Another big loss.
Also you need 5 psu + the heaters.Not very economical.
Normaly a outputcircuit like this needs an input somewhat more then Vspeaker/2 ,allready rather lage, with this feedback to the cathodes you need even 2/3-th more.
Mona
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Old 15th February 2013, 10:50 PM   #36
midmoe is offline midmoe  United States
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ketjie...thank you so much for the great, well thought out schematic....you do't like it or you don't like "it" ? I don't know if you built it and don't like the sound or don't like it from a design perspective ? As it has 6 output tubes instead of the shown 2, if you did build it I am hoping you made room for 4 more outputs......if... The screen criticism is valid, however. It is lossy, and needs cleaning up, but does the job for now and am using it on next monoblock......midmoe ps. sounds better than the mac.

Last edited by midmoe; 15th February 2013 at 11:10 PM. Reason: misspelled
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Old 16th February 2013, 11:10 AM   #37
midmoe is offline midmoe  United States
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looking into the rca tube manual for likely 25 volt ballast tubes to use, I came across a 25B5, refered to as a "direct coupled power amplifier". It consists of two triodes with the grid of the first triode hooked up internally to the cathode of the second triode, with no external attachments ! I'm sure it somehow works, but am puzzled as to how the references to ground are missing to the oddball setup, with no way to set bias on usual places.....since the tube is dc coupled, it must use a staggered supply voltages, one side getting double the b+ than the other....sure seems strange to build a tube like that. It is an old-school 6 pinner, so maybe they would have hooked it up externaly, but ran out of pins.
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Old 16th February 2013, 11:40 AM   #38
Ketje is offline Ketje  Belgium
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No I have no intentions to build it.Far to much psu's and very poor output versus consuption.At least change the connection of the screengrids.
As for that odd tube,this is whatI found.
Mona
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File Type: jpg 25B5.JPG (42.1 KB, 233 views)
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Old 16th February 2013, 02:37 PM   #39
cnpope is offline cnpope  United States
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Quote:
Originally Posted by midmoe View Post
...in fooling around with the series string in driver section, I placed the 12AU7 and two 12BH7s in series w/diode rectifier and put in as additional voltage drop a 25Z5 tube from the late 30's. Everything seems to be lighting up in a normal fashion.
If that series string is being fed from 120V, then you are considerably overrunning all the tube heaters. Each of the 12BH7 and the 12AU7 tubes will be getting almost 17V rms.

Chris
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Old 16th February 2013, 08:35 PM   #40
midmoe is offline midmoe  United States
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chris each tube looks exacly as the brighness level as if in 6.3 vac setup.....regardless of what the meter says, if the fils glow just right, the voltage has got to be right. (each tube shows 10vdc on my vom meter) Have left it hooked up in series and hour, turned it back on after cooldown, had very minor "surge" of 12AU7 fils.....within norms. Some of the smaller tubes surge a little anyway even with standard hookup. I do have to use a 100 ohms paralleling 12AU7, to equalize it's drop with others...looking back over the thread, I see I forgot to mention this...sorry. Right now , I have a 100 ohm, 5watt, which runs normal warm...so that is the only extra heat generated inside the case with the driver fils. This setup will remove 11.3 watts of power from fil. xfmr. now still a little hot even with muffin fan. With the outputs taking 60.48w, that should help alot with heating problem. ketjie...yes the voltage doesn't go deep as there is less room to travel with the lower B+ 170....however, I am going for current depth, not voltage. Essentially attempting to see how close a tube can made to behave as a transistor. I imagine the impedance is down about as far a possibe with 6 tubes....nearing 200 ohms with max. heating of the 1000 ohm, 10 watt rheostat with white noise taken as reasonable approximation. Yes the screen circut is lossy, have wired and rewired the prototype so many times, don't want to stress the sockets anymore, plus I'm using solid wires which can't take too much movement. The screens will be fixed this coming week. I put such a lossy matrix in to quiet the overshoots on large bass notes...this was before the "freddie drive" was in....I'm quite sure a change back to a more normal screen wiring can be made without blowback in next one. I got in all the tubes, xfmrs, caps and etc....should know by middle of next week how to fix that and other small issues.. the "tread" polished alumnum top looks cool, Almost a mirrored surface.....midmoe
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