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Velleman K4040

Posted 12th August 2010 at 04:53 PM by alexcp (My DIY projects)
Updated 26th May 2011 at 12:54 PM by alexcp

Then was the K4040 from Velleman. Contrary to some reviews, I found this amp sounding rather nice, particularly after I replaced the EL34 tubes in the output stage with separately purchased matched quads. However, the sound does not quite match the price, and I keep this amp mostly for its looks.

Update: I modified this amplifier, leaving little of the original design. See a later post with the details.
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Posted in Tube power amps
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Old

S5 Electronics "L" series tube amps

Posted 12th August 2010 at 04:52 PM by alexcp (My DIY projects)
Updated 5th May 2015 at 12:38 PM by alexcp

I started with a Model 8LS stereo amp from S5 electronics. Later I put it into a Hammond enclosure and replaced the tranformers with Edcors.

Separately, I built a Model 16LS, which is the same thing with a doubled output stage, giving a very similar sound. Both use a 5670 double triode in the voltage amplifier and phase splitter, and 2x6005 (4x for the 16LS) in the PP output stage.

Both versions are very easy to build, nice with vocals, but not quite HiFi - see the FFT charts. Matching tubes and the resistors in the split-load phase splitter circuit helps to reduce distortion.
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Posted in Tube power amps
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Old

Aleph "MJ" using SemiSouth SJEP120R100 outputs

Posted 8th August 2010 at 09:29 PM by Tea-Bag
Updated 9th August 2010 at 12:34 PM by Tea-Bag

So I believe I am finished with the Mini-A version modified for SemiSouth R100 output. The MJ is not in reference to Michael Jackson, rest his soul. Simply a reference to Mosfet input, JFET output.

Technical pieces:
R8 is a 1K pot. This allow for some DC offset adjustment.
R18, This affects drain current to differential pair. This value is lowered. I chose 220R resistor since I have a bunch of them. Papa presented this as needed on mod's in general for the lower VGS of the R100 (~1.5v)
R19, gate resistor to Power JFET R100. This is lowered to 47R. We see with F1J and F2J that gate resistors are lower.


Rail Voltage is +/-24v
Source voltage is .425v and is largely determined by the 100K pot settings and heatsinks on hand. The real value of the pot is ~ 70-80k here. I let the IRF240's run no higher than 65c and R100's no higher than 70c.


Sound

Previously I had R18 at 392 default and R19...
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Old

Mis-understood ArT - Part II

Posted 6th August 2010 at 10:15 PM by tomtt
Updated 19th January 2011 at 11:42 PM by tomtt

i actually spoke to Taylor Swifts agent.

he cleared up a few unanswered questions,

i had about the 'Kanye/Taylor incident.'

http://img836.imageshack.us/img836/7...itowebcam5.jpg

Click the image to open in full size.

http://gifsoup.com/MTMyODAxNw


http://www.radioworld.com/article/105742

http://www.fundinguniverse.com/company-histories/Ballantyne-of-Omaha-Inc-Company-History.html
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Old

Up and running

Posted 4th August 2010 at 09:08 PM by stripe157

As of August 4, at 4:01, this is an official, working amplifier!

Once I decide on a volume control knob, I'll make a wooden face plate for it and call it finished... for now.
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Old

PassDIY LDR

Posted 30th July 2010 at 10:10 PM by DougL
Updated 14th September 2010 at 06:33 PM by DougL

http://www.diyaudio.com/forums/analo...ml#post2258073

This looks cool.
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Old

Binding posts/RCA

Posted 27th July 2010 at 04:11 AM by stripe157

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Old

How low can you go?

Posted 26th July 2010 at 06:46 AM by abraxalito
Updated 31st August 2010 at 04:28 AM by abraxalito

The prices of DVD players just keep on going down here. Yesterday I bought my very first 99RMB [that's under $15] model in Carrefour. I couldn't wait to get home to see how it sounded.

First up I listened to one of my favourite BIS recordings - Mozart 40 in a version for piano, flute and strings. The sound really wasn't as bad as I'd expected - the cello sounded really 'reedy' rather than full-bodied and the flute was akin to a sopranino recorder in its higher register with very little bloom. But there was a fair approximation to a soundstage and really quite decent dynamics, not at all 'bitstream'.

Rebecca Pidgeon's 'Spanish Harlem' is the test disc I use to check for sibilance (it has lots of 's' sounds), and sure enough there was some but definitely not terrible considering the price.

This undoubtedly had potential for the price - I wondered if it could be improved. Inside almost all the functions are integrated on the MediaTek chip (although it...
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Old

Chassis by Dell... with tubes

Posted 20th July 2010 at 06:15 PM by stripe157

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Old

Chassis by Dell

Posted 20th July 2010 at 05:00 PM by stripe157
Updated 27th July 2010 at 07:48 AM by stripe157

Under construction:
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Front:
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With some black satin sprayed on:
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With TubeLab.com's Simple SE board:
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