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homeskillet homeskillet is offline

diyAudio Member

About Me

  • About homeskillet
    Location
    Seattle
    Occupation
    Craftsman and Musician
    Country
    United States

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Total Posts
Blog - Journey to the Center of the Circuits of Homeskillet
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General Information
  • Last Activity: 18th December 2014 07:46 AM
  • Join Date: 31st March 2010

Blog

Latest Blog Entry

Posted 6th August 2013 at 05:43 AM by homeskillet Comments 0
Posted in Uncategorized
Aug. 27th, 2013 edit:
Tapping the output transformer as a balanced secondary is totally goofy as was determined by Osvaldo de Banfield and Cnpope (Chris) here:
http://www.diyaudio.com/forums/tubes...madness-2.html

I'll leave it posted here just to show that I'll try just about anything and to show that it's unwise.

Aug. 7, 2013 edit:
I was just looking for the Hawksford and Mills current amp paper on google and I found this very blog post so I thought I would point out a potential drawback to the following feedback technique. Hawksford and Mills claim that using a sense resistor to the ground return from the speaker introduces a distortion similar to "interface distortion" in voltage amplifiers.

There is very little I could find about interface distortion.

As far as I can see it, this feedback scheme may introduce back emf from the speaker and feed it back to the amp...

Posted 5th August 2013 at 05:34 AM by homeskillet Comments 0
Posted in Uncategorized
Continued after some listening and more tinkering from here:
http://www.diyaudio.com/forums/blogs...e-big-amp.html

It seemed lacking in the high end so I added a bit more capacitance to the bypass cap on the cathode resistor on V1.

This picked the high end up nicely. I then hooked the speaker up to the 16 ohm tap and used the 8 ohm tap as the feedback center tap. This resulted in a bit more output and I like the sound just fine.

The volume seems to increase after it's turned on a while. Also, it needs a B+ fuse in the event that V1 doesn't draw then V2 will have no bias and will draw tons of current and then will dump tons of current into it's cathode resistor.

The schematic posted here is updated with voltages and values done to the best of my ability and it sounds very nice. It's not a finished design but great for experimenting.

I will be setting this aside as my curiosity is leading...

Posted 3rd August 2013 at 05:55 AM by homeskillet Comments 2
Posted in Uncategorized
Hi. Here continues the tinkering continued from the forum post:
http://www.diyaudio.com/forums/tubes...-feedback.html

I took out that EF184 and the plate to plate feedback loop since I read that devices with a more stable performance without feedback sounded better once it was applied than devices that rely on feedback for their very operation. This seemed about right and I was tiring of the sound a bit.

The plate to plate feedback was the only way I could find to stabilize the EF184 and 6550 in this basic configuration and give any reasonable results and wiring it satisfied my curiosity so apart it came.

I replaced V1 with a 12AT7 and wired it in parallel since I figured it could use all the help it could get to drive the 6550.

The global feedback is my first attempt at current feedback. It's basically part of my first attempt at feedback at all.

I...
Recent Comments
Hi. Sorry I didn't see...
Posted 20th December 2013 at 05:42 AM by homeskillet homeskillet is offline
There's no feedback...
Posted 20th August 2013 at 12:55 PM by Michael Bean Michael Bean is offline
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