[jdkJake]

Nice work cfcubed! Very original.
 
I would definitely like to see your acrylic bending technique on the other thread. Are you going to use something like MEK to clear the edges?

 

[cfcubed]

Thanks.    Yes either M.E.K. or Weld-On Acrylic cement will do the trick (Edit: found Weld-On helps clear the edge but tricky work w/torch can make it clear).   Maybe you're in on this but had to figure out the cutting bit when I cut down my M/C windshield using the technique here:
http://tidyville.roadstarclinic.com/windshield.html
then its just finding a piece of wood that's => the target interior width, heating top/bot of acrylic bend spot (w/heatgun) & making its right angles by pushing it down over the wood's edge.
 
OK will post some build tips & pics in that other thread in a bit.  Here's one more pic to show some of the guts:
 

 
BTW the angled ends of alum plate & assoc gaps were intentional to provide venting, my circ saw just got a bit carried away on 'em
Quote:

Nice work cfcubed! Very original.
I would definitely like to see your acrylic bending technique on the other thread. Are you going to use something like MEK to clear the edges?

 

 

[liamstrain]

That looks great!

 

[Rescue Toaster]

 
Finally did a test fitting of my amplifier. Should hopefully be able to listen to/RMAA it sometime next weekend! (time permitting). I had this cool old CATV amplifier extrusion case that has a full RF shield/seal around it, so I'm going to use that (the PCB's *barely* fit, I had to file them down a bit in the middle). I hope it has enough dissipation laying down (since the fins run lengthwise). Otherwise I might turn it on end and make a combination amplifier/headphone stand or something...
 
There's a gas discharge regulator & a CCS that will be mounted to the top plate. Either with the tube standing up normally, or I'll make a little wooden offset (I plan on making wooden endcaps) so the tube lays horizontally, since gas discharges work in any orientation.

 

[Bow to Ed]

These are my builds. They are like a Szekeres headphone buffer with some differences. There was a project like this on DiyAudioProjects.com but my amplifiers are a little different still.
 
My first build. The base is a polished and lacquered piece of plywood. I wanted to keep it simple. There is no hum or noise and it sounds very good. When I turn the volume up all the way there is audible clipping distortion but that goes way beyond the loudest volume I can stand to hear. The only way I would go that high is if I were to set my headphones (Skull Candy) down on the desk and use them as speakers.
 

 
 
The second build. I made this for my mentor who runs a Yahoo Group on vacuum tubes. It features increased filtering capabilities and a better enclosure. The enclosure was made of 9/16" plywood and painted with Rustoleum Gloss Black.
 

 
The amp features the following:
 
-DC input with filtering. The first amp uses a 1-ohm resistor into three 470 uF caps with +12v in. The second amp will use a 7.5-ohm resistor into a 1000 uF cap with +15v in. These schemes should remove all noise from the power supply.
 
-50K input impedance due to the volume control knob.
 
-Class A triode stage a la 12AU7 with un-bypassed cathode. Other tubes tried in this spot were EH12AT7, Sylvania 12U7, and JJ ECC82. The last tube doesn't like the low voltages so much. I don't know why.
 
-Direct-coupled output to a class-A MOSFET output stage. The MOSFETs are IRF510 in my first build and IRF610 in the second. The output stages are loaded with constant current sources to about 100 mA each. The output capacitors are 470 uF types bypassed by a 330 nF green film cap.
 
-Zero negative feedback. I don't have anything against using it but I just didn't implement it into this design.
 
Also I can show off something I once called FET-Zilla. It is a similar amplifier to the types described above. The only differences are that the amplifying device is an MPF102 instead of a 12AU7 triode and the output MOSFETs are loaded by resistors at a much lower current instead of CCSed. Nonetheless, it was still a pretty good amplifier and is worth mentioning.
 

 

 

[G.Trenchev]

 
This is my small hybrid amp.Regulated power supply inside,powered by notebook charger.

 

[Starfire]

Two channel B22 I just finished, just in a cheap pactec case for now but sounds great no matter what case is around it
 

 

[Tilpo]

Two channel B22 I just finished, just in a cheap pactec case for now but sounds great no matter what case is around it
 

Very nice pictures! You should have put in a little more effort and turn the 'B' into the proper 'β' :rolleyes:

Is it me, or do you have an extremely long DC umbilical cable?

Seeing this makes me all the more anxious to finish mine. Currently awaiting JFET's blew through accidentally switching the gate and source pins.

 

[Starfire]

Yeah true about the B, it's abbreviated so much I forget!  Still needs a knob too.
 
The cord is long about 4 feet, but I hated to cut it after all the time spent braiding it.
 
I'm actually thinking about adding the ground channel and I'd need a better case then.

 

[davisoly]

This is just spectacular. I can only imagine how "Plain Jane" it would look without the illumination. Great idea Sweetie!
Lynn

 

[qusp]

Quote:

Yeah true about the B, it's abbreviated so much I forget!  Still needs a knob too.
 
The cord is long about 4 feet, but I hated to cut it after all the time spent braiding it.
 
I'm actually thinking about adding the ground channel and I'd need a better case then.

imo stick with the 2 channel, or go all the way with a 4 channel. its a tired old fashionable argument, but i see no reason to go with a buffered virtual ground in a home amp and since your layout appears sound i think it will match or better the 3 channel.

 

[Starfire]

My only reason was I had read the ground channel widened the soundstage.

 

[jcx]

if the the "3-channel" active gnd has an audible effect then it proves it is less accurate - use a piece of Cu Roof flashing for output, signal gnd between boards and you won't have measurable "gnd contamination" - not that it is perceptible with Class A amps anyway
 
EDIT - we should continue any circuit implemetaion discussions in a build thread - I edited to add this to cut down on non-subject posts

 

[Starfire]

Well then is balanced really that much of an improvement (I have no plans of going balanced though)

 

[Tilpo]

Well then is balanced really that much of an improvement (I have no plans of going balanced though)

As far as I know balanced is only useful when you need very long wires, which is never the case in rigs for personal use.
Balanced mainly finds its use in professional applications. In personal applications there really isn't any point in getting balanced except for the doubling of power output of the amplifier.