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Build your own case

Posted 20th November 2009 at 08:52 PM by DougL

http://www.diyaudio.com/forums/const...ml#post1987690

These are answers I need.

Thanks.
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Old

Delivery

Posted 20th November 2009 at 06:48 PM by Bas Horneman (Bas Horneman's diyAudio.com blog)

Look what the mailman/woman dropped at my casa.

A matched quartet of GM70's (Almost ashamed at how little I paid for them) GM70's are for a SE GM70 amp with MQ parafeed iron.

And the 500R trimpots and 0,22uF caps for the Baby Huey.

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Old

To do

Posted 20th November 2009 at 02:53 PM by relder (Rob's active 3way with transconductance chipamps build blog)

A main reason I'm active on this project is the event coming up on the 5th. For me there's nothing like a deadline to get me out in the garage.

A lot left to do:
  • MLS measurements - on/off axis at varying output impedances for 3 drivers will make for quite a few measurements
  • Figure out how to enclose the mid - I'm thinking open back at the moment
  • Design the active crossovers in Soundeasy
  • Build the active XOs - point to point likely using FirstWatt B1 type buffers (two JFETs isn't much more work than an opamp)
  • Paint

Two weeks left!
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Old

Construction of a P2P LM3886 gainclone part 2.

Posted 20th November 2009 at 02:44 AM by wintermute (Wintermutes Rantings)
Updated 25th November 2009 at 11:18 AM by wintermute (Added to category amplifiers)

edit: applogies to anyone viewing this at less than 1280 screen width... It formats properly with that (two images side by side) but I'm not going to go and redo all the images now!!! I already did twice....

OK Continuing on where Part 1 left off. The next step was to attach the Power Supply wiring. I will continue the numbering from the first blog entry for consistency.

18. Click the image to open in full size. 19. Click the image to open in full size.

images 18 and 19 show the completed amplifier with +ve -ve and zero volts wires connected. Note also that there is a separate zero volts return from the zobel capacitor to the star ground on the PS board. The red wire is the +ve the blue wire the -ve and the green wire is the zero volts. The return for the speakers is direct from the speaker output jack to the star point on the PS board. So in all there...
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Posted in amplifiers
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Old

Construction of a P2P LM3886 gainclone part 1.

Posted 19th November 2009 at 08:18 AM by wintermute (Wintermutes Rantings)
Updated 17th April 2011 at 01:19 PM by wintermute (Added to category amplifiers)

edit: 17th April 2011. Just to set the record straight, although I refer to this chipamp as a "gainclone" strictly speaking it is not. A gainclone is I believe actually a clone of the 47 labs gaincard, however many people refer to chipamps as gainclones incorrectly (myself included).

edit: apologies to anyone viewing this at less than 1280 screen width... It formats properly with that (two images side by side) but I'm not going to go and redo all the images now!!! I already did twice....

Well I said about 4 years ago that I would do a build writeup for my P2P gainclone. I took all of the pictures but never got around to it. I'm off sick and lacking energy so decided it was as good a time as any to have a crack at it

I started out with the BrianGT schematic. I wanted to build something that people were using and was likely to just work. Here is a copy of the schematic
Click the image to open in full size....
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Old

Ordered 500R pots for the driver stage.

Posted 18th November 2009 at 08:27 AM by Bas Horneman (Bas Horneman's diyAudio.com blog)

And while I was at it I saw some 0,22uF Epcos MKV from the same seller. The Epcos will do duty as coupling cap, as I've seen good reports (anecdotal) on them.

I asked Ian (gingertube) what the 470R resistors were for. Because I figured the CCS would take care of everything of the balance.

Here was his answer:
Quote:
The 1K pot is to set balance in the diff amp. The resistance in the triode cathode degenerates the tube gm (Ia/Vgk). Sweeping the pot wiper from side to side varies the amount of degeneration on each of the 2 triodes until they match. This is the minimum distortion condition for the diff amp. As we don't want to throw away gm un-necessarily we don't want those resistance values too high - just high enough to be able to adjust for matching behavior.
For a random sampling of 12AX7 and ECC803S that I had, 1K was too much, 100R was'nt quite enough so I dropped the 470R on each side of the 1K pot which effectively makes that pot about
...
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Old

Slowly but surely making progress

Posted 16th November 2009 at 09:36 PM by Bas Horneman (Bas Horneman's diyAudio.com blog)

I have used a diy fluid for drilling for the first time. Used bicycle chain oil...water and detergent. Quite happy with it. Drilled the largest hole yet. And it looked almost professional.

Also a photo of the oak enclosure after it was treated with boiled linseed oil. The oil makes the oak enclosure look a lot better, it really brings out the grain. As usual I don't have "before" pictures to show the difference. (the pictures below had a partial coat already)

I'm not sure what to seal the wood with. Suggestions are welcome. Right now I'm thinking about shellac.
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Posted in Building
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Old

cyrus2 and psx spares

Posted 16th November 2009 at 12:50 PM by cyrusnut

i dont know if i am doing this right, but i need a potentiometer for a cyrus2 amp, and any metal casings for the toggle on/off switch variety including the psx.cyrus do not supply spares, having tried on numerous occasions, and getting nowhere. please help, there must be one out there somewhere. my email is scotchb@fsmail.net. awaiting reply in ernest. cheers.
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Old

3 way post #9 - tweeter distortion measurements

Posted 16th November 2009 at 01:50 AM by relder (Rob's active 3way with transconductance chipamps build blog)

Unlike the mid and woofer - the tweeter doesn't seem to show any gains under current drive.
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Old

3 way post #8 - mid distortion measurements

Posted 16th November 2009 at 01:45 AM by relder (Rob's active 3way with transconductance chipamps build blog)

Some decent reductions in 3rd harmonic.
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Posted in 3 Way
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