2 x 12au7 amp running on 9 volt adaptor and smps

[zambo]

Thanks for the info Rick. Very good reads. I sent taylor a pm asking if he knew of or was interested in designing/building such a device. Dont ask dont get right? Do you have any new amps since Obsession? I love your work. 

[iccaros]

I have some 6af11 compactrons. Which have two triodes and a pentode in the glass. the 65 ma of  the smps should be enough (I estimate a draw of 35ma not counting heater) to get 2 -3 watts out (3.24 by the math .018 * 180) .


the squirrel monkey http://www.solorb.com/elect/musiccirc/squirrelmonkey1/


Zambo you might be able to use one of these tubes, just adjusting your design, to create that Case amp.....
I bought 4 of these tubes on ebay for $12

[zambo]

i was reading about compactron amps on ax84 and saw that someone had mixed results with them. I havent tried but they seem interesting for sure. I love the idea of 2 pre and a power tube all in one envolope.

[iccaros]

i was reading about compactron amps on ax84 and saw that someone had mixed results with them. I havent tried but they seem interesting for sure. I love the idea of 2 pre and a power tube all in one envolope.

The ones I saw issues with had two pentodes in the same tube, sharing a cathode.  I am not sure the issue, but I am sure its fixable.

I just got sockets in, I was going to use my 24.6 - 0- 24.6 backards and get 120 out from a 24v wall wart.. (should work yes?)

instead I have two of those SMPS on order.. Still need an output transformer to finish.. But I'll see if I can reproduce your tone with it..

[El Heisenberg]

Hey where can you buy output transformers on the cheap??? 30 bucks is alot to me.

[iccaros]

Hey where can you buy output transformers on the cheap??? 30 bucks is alot to me.

Whats a good price?

[iccaros]

Where is the grid return resistor for the upper output triodes?  Also, your coupling capacitor to the output stage comes off the wrong side of the plate resistor and so does the coupling cap from the first stage to the second stage.  If it works, you have something different in there from what you drew.  BTW, is that a tone stack at the input to the second stage?  I don't see any pots and there is nothing in a position to act as a simple volume control.

Sounds like the 11K taps are a bit high for a push-pull parallel triode output.  I would expect the optimum to be about half of that.  Some people drive reverb tanks from a single-ended 12AU7 and the impedance is on the order of 2500 ohms.  PPP 12AU7's may be around 2500 ohms plate-to-plate, but I don't have actual figures.  Triode output impedances should definitely be less that pentode or beam power tube impedances.

I would also advise a lot more capacitance at the input to the SMPS.  A power converter is a negative resistance at the input since the internal feedback (if regulated) causes the current to increase when the voltage decreases.

I started my own thread
http://www.diystompboxes.com/smfforum/index.php?topic=91606.0

[zambo]

I just realized there is a .0022uf 1kv cap that goes from the right half to the left half of the ot on the primary side or on pins 1 and 6 of the power tube closest to the ot. I dont really know how to update it but its a pretty important cap.

[iccaros]

I just realized there is a .0022uf 1kv cap that goes from the right half to the left half of the ot on the primary side or on pins 1 and 6 of the power tube closest to the ot. I dont really know how to update it but its a pretty important cap.

Updated.. Check the drawing on the (2) page, It should have updated to having the changes

[zambo]

almost, instead of going right to left it would have to go verticaly bridging the right and left sides of the ot primary. Thanks!

[iccaros]

almost, instead of going right to left it would have to go verticaly bridging the right and left sides of the ot primary. Thanks!

Ok,, how's it now?

I looked at the firefly this time

[zambo]

Thats it! Now it looks perfect. Thanks again!

[iccaros]

Zambo
Can you read what your amp is pulling current wise? This would give us a better Ideal of needs. Or at the least be helpful for me

[zambo]

will do asap. where would I measure that? Across the.........b+ to ground from the ot primary centertap? positive lead on ct neg on ground? sorry to be dim....just still learning this stuff..

[iccaros]

Just from the high voltage side.. just pull from the output of the power supply and the connect the meter between so that all current from the supply through the amp must flow through the meter. Ensure your meter is setup to read current (amps) which on mine means you must plug in differently.

[Scruffie]

I have some 6af11 compactrons. Which have two triodes and a pentode in the glass. the 65 ma of  the smps should be enough (I estimate a draw of 35ma not counting heater) to get 2 -3 watts out (3.24 by the math .018 * 180) .


the squirrel monkey http://www.solorb.com/elect/musiccirc/squirrelmonkey1/


Zambo you might be able to use one of these tubes, just adjusting your design, to create that Case amp.....
I bought 4 of these tubes on ebay for $12

I saw your Squirrel Monkey Before! Very nice, I really wanted to get one/build one when I saw it, just the idea of a single tube amp practice is somehow appealing.

[iccaros]

Sorry that is not mine, I found it on the web.. I am planning on building it this year.. I have a Champ that died,,, well not mine a friends,, and he wants me to test this build using the Champ parts with this tube.. See what I can do..

[iccaros]

Ok I have two Taylor edge SMPS http://www.tayloredge.com/ in, they ship fast, ordered on Friday got on monday..

In am going to attempt this once I get a transformer, I have been using 70volt line transformers, which I do not believe will cut it..

Also I need more resistors and caps.. The high wattages ones, I always seem short on. .

[zambo]

If you get the higher voltage 400+ caps you can always switch to a hammond 269ex  power trans later if you like. Its a nice option to have. I used the small bear 250v caps in mine as thats what i had around. Looking forward to hearing your amp sir! sorry i havent measured the current yet on mine. I am building a proper board for the ps and caps. I also got side tracked building a seperate tube reverb  the good news is it works...it hums a little and I need to enclose it.....another thread I guess. 

[iccaros]

tube spring reverb  or a Tube reverb  no spring..


I got a bunch of 400 and 650 caps, but wrong values.. I did not lot of robotics for work so digital electronic take different caps..  so stocking up..