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Kt-88 ultralinear project

Posted 17th August 2010 at 06:51 PM by NBBN_amplifiers

Hi to All,

I'm designing a KT-88 Ultralinear amplifier using the idea of Satoru Kobayashi 2002.
The pre amplifiers is a solid state using a TL-72 with gain 10 and the second stage i have the superb DRV134 Burr-brown (Low distortion: 0.0005% @ 1KHz) which is a differential output amplifier.
Following comes the 6N1P svetlana and the EI 12BH7AEG direct coupled and the last stage with KT-88.
The most important part is that it's all in one, I mean, all in one board. I integrated the high voltage power supply regulator and the low voltage for the op-amps in the board eliminating wires around.
I've been working in this board for more than 3 months and creating BOM, calculation an so one. So far the project is around U$ 1266,00 including all parts, not board, and transformers plus the tubes.

Attached you can see the print-screen of the board. I didn't send to production yet, and i plan to go slowly in this project due the cost mostly...
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Old

Digital Audio Signal Generator

Posted 15th August 2010 at 01:50 PM by alexcp (My DIY projects)
Updated 15th August 2010 at 04:18 PM by alexcp

This handy instrument is a version of the design published in Australian Silicon Chip (a subscription is required to view the details of the article). It is based on a dsPIC33 microcontroller, has TOSLINK and S/PDIF digital outputs (44.1k, 48k and 96k sample rates) and a stereo analog output. Output frequency, phase, attenuation, and other parameters are set by the keyboard. It produces sine, square, triangle, and sawtooth waves and has a variety of modes. It can be powered by an external DC source or a battery. The article claims low distortion for sinewave (less than .06%) and even lower with a good external DAC, but I did not have a chance to verify that just yet. Highly recommended.
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Posted in Instrumentation
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Old

Creek with a tweak

Posted 15th August 2010 at 11:05 AM by alexcp (My DIY projects)
Updated 18th August 2010 at 08:24 PM by alexcp

One of the more interesting projects for me was building a tweaked clone of Creek 4330. It was designed for Creek by diyAudio member x-pro; the schematic is available on his web site. The tweak was the topic of x-pro's paper and was discussed in this forum. Last year, this design generated enough interest on one of Russian DIY forums for a group buy of PCBs and some components. I used a PCB from that group buy, a compact chassis from modushop, and a K4700 speaker protection kit from Velleman. Today it is this amp that I use most often for music, and I am very pleased with its sound. Thank you x-pro for sharing the design!
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Old

understanding capacitor Bob Pease

Posted 14th August 2010 at 02:27 PM by klewis
Updated 28th August 2010 at 03:07 PM by klewis

http://www.national.com/rap/Applicat...570,28,00.html

OS-Con Capacitors
http://archive.chipcenter.com/eexpert/akruger/akruger007.html

Vishay MKP capacitors at Digikeyhttp://search.digikey.com/scripts/Dk...+63V&x=26&y=21
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Old

The Speed Of Sound

Posted 14th August 2010 at 06:06 AM by Artmaster

my sound world you can see there:
ArtMaydan
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Old

CMoy and PPA

Posted 13th August 2010 at 09:37 PM by alexcp (My DIY projects)
Updated 6th April 2011 at 01:35 PM by alexcp (Added pictures)

Of course I built the ubiquitous CMoy. It was a big improvement over various built-in headphone amps (e.g. in a TV) and added headphone capability to where it did not exist (e.g. to a Playstation).

Encouraged, I built the PPA project with a Young-Jung power supply. The enclosures for both the amplifier and its power supply are from modushop.

On first power-on the amp oscillated at 12 MHz when connected to headphones. The oscillation was inaudible but clearly visible on a scope. A quick look at head-fi.org showed that PPA instability is not a new problem. I reduced the value of R11 (see PPA's schematic), which eliminated the oscillation and improved the sound. I replaced the recommended OPA627 with LME49710.

PPA is positioned as a high-end DIY headphone amp, and it is in this project that I felt how subjective "high-end" is. PPA is a nice amp, but a true high-end device like Musical Fidelity X-CANv8 simply blows it away.
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Posted in Headphone amps
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Old

BantamDAC

Posted 12th August 2010 at 07:57 PM by alexcp (My DIY projects)
Updated 15th August 2010 at 11:09 AM by alexcp

ezDAC lacked a USB input, so I leveraged my newly acquired SMD soldering skills building BantamDAC from a kit. While PCM270x-based USB DACs are rather common, BantamDAC is a compact (1" x 2"), neat version.
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Posted in Digital Sources
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Old

ezDAC

Posted 12th August 2010 at 07:39 PM by alexcp (My DIY projects)
Updated 16th August 2010 at 07:05 PM by alexcp

After power amps, speakers and a preamp I wanted to try my hand in digital sources and built a version of ezDAC. It is a fairly simple DAC with a CS8416 digital receiver, an AD1896 sampling rate converter, and a PCM1794A with a passive I/V converter for the DAC proper. Nothing fancy, but sounds as good as my DacMagic.

I used three separate 3VA toroidal transformers (for digital circuits, the DAC, and opamps) in the PSU. The enclosure is from modushop. I had to re-create ezDAC's PCB using the free version of Eagle (which I had never used before) and learn to solder SMDs.
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Posted in Digital Sources
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Old

Elekit TU-879S

Posted 12th August 2010 at 07:24 PM by alexcp (My DIY projects)
Updated 16th March 2013 at 02:02 PM by alexcp

Elekit TU-879S is the best sounding kit I have ever built. Thank you TubeDepot.com for selling these kits. With my DIY full range speakers I mentioned a couple of posts earlier, the sound is fantastic.

Update: one of the original 6L6 tubes got blue sparks inside. As this amp can use KT88, KT66, or EL34 without any adjustment or modification, I replaced both 6L6s with EL34s left from the K4040 project, but the sound deteriorated. A replacement 6L6 from TubeDepot.com restored everything.
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Posted in Tube power amps
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Old

First Watt B1 clone

Posted 12th August 2010 at 07:19 PM by alexcp (My DIY projects)
Updated 12th May 2013 at 04:09 PM by alexcp (Added photos)

What to say... B1 is a great design by Nelson Pass. Easy to build, absolutely transparent to the sound, compact, PCBs are available. I built one, using Nelson Pass' gerbers for making my own PCB, in an enclosure from diyenclosures.com (which sadly seems to be defunct now). The big blue film caps are 10uF Evox Rifa PHE426.

Update: I added a relay input selector, which reduced crosstalk between inputs. I also built another B1 clone (the last three photos), in an enclosure 1U (40mm) high.
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