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I returned to DIY electronics in 2009 after a 20 year pause by building a few kits to get in shape. This blog is for me to keep track of my progress.
Old

24/192 DAC

Posted 7th July 2011 at 12:46 AM by alexcp (My DIY projects)
Updated 16th March 2013 at 02:33 PM by alexcp

Built from a kit. I don't like the sound at all.
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Old

Grounded Grid Preamp

Posted 7th July 2011 at 12:43 AM by alexcp (My DIY projects)
Updated 16th March 2013 at 02:35 PM by alexcp

Built from the kit from Bruce Rozenblit. Very nice one, but is not being used - it has too much gain for any of my systems. I will probably sell it.
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Old

Another Gain Clone

Posted 8th May 2011 at 02:07 AM by alexcp (My DIY projects)
Updated 7th July 2011 at 12:28 AM by alexcp (Added photos)

Unsatisfied with the sound of my gainclone amplifier, I re-used the enclosure and the power supply for a gainclone along the lines suggested by Bob Cordell, whose implementation of an LM3886 based amp was praised by at least one member on the NJ audio society.

I skipped both the Klever Klipper and the toroidal air core output inductor, and kept only 10,000 uF per rail in the PSU. The schematic can be found in Chapter 27 of Cordell's Designing Audio Power Amplifiers. The PCB was designed to re-use the existing mounting holes of the ChipAmp's PCB.

The result? Better than with a plain vanilla chip amp, but still not good enough for music. Perhaps I should not have limited myself to re-use of the PSU et al. but should have taken all the details of my implementation seriously.
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Old

Velleman K4040 mods

Posted 8th May 2011 at 12:32 AM by alexcp (My DIY projects)
Updated 4th May 2014 at 12:59 AM by alexcp

I posted some time ago a note about my Velleman K4040 amplifier. The sound of the amp as built from the kit was unremarkable and definitely not in line with the price. Lacking experience with tubes, I was looking for some time for well documented mods to the kit.

I found two 2006 posts here and here and implemented them rather directly. The only difference is that I used IXCP10M45S instead of a pair of J508 current sources in each channel and replaced the 1N5408 rectifiers with UF5408 instead of adding noise suppressing capacitors in parallel to them.

The mods did not leave much of the original Velleman design in place; the result, however, is a remarkable improvement in sound!

However, two problems remain: (1) I got hum that wasn't present before the mods; and (2) a two-year old running around doesn't get along with eight hot, attractively glowing tubes. The project is shelved until a better time.

For future reference: The toroidal...
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Posted in Tube power amps
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Old

Low effort Class D with ready made modules

Posted 5th April 2011 at 04:45 PM by alexcp (My DIY projects)
Updated 6th April 2011 at 01:29 PM by alexcp

To try out Class D without working too much, I picked two ready-made Class D amplifier modules: one is the $45 2*100 Watt Class-D Audio Amplifier Board from Sure Electronics with the optional $10 volume control board, the other is the $199 IRAUDAMP7S from International Rectifier.

The Sure Electronics module is based on Tripath's TK2050 chipset. Powered from a 150W 24V SMPS from Mean Well, it predictably puts out about 22W RMS to a 8 ohm load. (The declared 2*100W requires a 30V supply and a 4 ohm load.) The sound and the measurements are decidedly mediocre, although at the $45 price, the module still may be a good value. Also, the volume control board feels odd, as the knob only adjusts volume after a push; another push disconnects it again.

The IRF module requires dual rail supply, for which I chose an SMPS400A180 by hypex. With +/-40V rails, the amplifier delivers 100W RMS into a 8 ohm load. The measurements are good, and the sound is very interesting for...
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Old

Digitally controlled class D

Posted 8th February 2011 at 07:24 PM by alexcp (My DIY projects)
Updated 17th December 2011 at 01:24 PM by alexcp

I wanted to build a Class D amp based on TI's PurePath chips - e.g. TAS5086 PWM processor and a few TAS5162 power stages - until I read Bruno Putzeys' "The Truth About Digital (Class D) Amplifiers". He makes a convincing argument that digitally controlled class D is a dead end street. I also noticed that very few people around here have been writing about PurePath. Shall I look at the UcD patent and application note, as well as ready made Hypex modules, instead?
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Old

DCPP aka Engineer's Amplifier

Posted 8th January 2011 at 01:09 AM by alexcp (My DIY projects)

I just built a Distortion Cancelling Push Pull (DCPP) amplifier designed by Peter Millett. It sounds very nice, was fairly easy to build, and is rather inexpensive. Thank you Peter for the great design!
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Posted in Tube power amps
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Old

Burning Amp 1

Posted 9th October 2010 at 06:52 AM by alexcp (My DIY projects)
Updated 16th March 2013 at 02:40 PM by alexcp

To get warm and comfortable on long winter evenings, I built myself a Burning Amplifier 1. With its 300W quiescent dissipation and ineffable ((c) Nelson Pass) sound, it is a nice winter time companion.

I used four heatsinks, each holdings two IRF250 MOSFETs in TO-3 packages and a PCB. Each pair of heatsinks is cooled by a quiet 140mm fan. Power supply uses a 400W toroidal transformer and 2x40,000 uF per channel; it is a dual mono configuration. The amplifier is housed in a 5U 400mm deep enclosure from modushop. Their "pierced base" was very handy to keep all the parts together without sacrificing the looks. Total weight is 23 kg (about 50 pounds).

The knob on the front panel was designed as volume control, but it looks ugly, so I will remove it.
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Old

LME49830 based amp

Posted 4th September 2010 at 06:02 PM by alexcp (My DIY projects)
Updated 8th October 2012 at 10:26 AM by alexcp

This is an implementation of National's reference design for LME49830 with two matched pairs of 2SK1530+2SJ201 per channel. The PCBs were made using National's gerbers (thus National's logos). Sounds surpisingly good, but it has just been completed; I did not have a chance to listen to it carefully yet.

Update: I rebuilt the amp as a pair of monoblocks, each delivering healthy 200W into 8 ohms. It now looks tidier.

Update: the original Gerbers from National are nowhere to be found since national.com was merged into ti.com. Attached are the original archives downloaded from the national.com.
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Old

YAGC (Yet Another GainClone)

Posted 4th September 2010 at 05:58 PM by alexcp (My DIY projects)
Updated 5th September 2010 at 07:59 PM by alexcp

This was unavoidable, I guess. Dual mono LM3886 kit from ChipAmp.com with Avel Lindberg's transformers in a wonderfully compact enclosure from Design Build Listen. I liked the simplicity but not the sound. Why is everyone so excited with gainclones? IMHO, Papa's Zen V4 is not much more complicated to build (although no kit is available), but is so much more an interesting experience!
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