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F5

Posted 28th January 2012 at 06:39 PM by alexcp (My DIY projects)
Updated 11th April 2016 at 08:27 PM by alexcp (Added photos)

Just finished fine tuning my First Watt F5 clone.

I built it about a year ago out of parts that I had on hand back then, including a power supply reused from another project. The resulting sound was rather disappointing. Now I spent time matching transistors and tuning the feedback network. The amplifier now is very close to the performance described in the original service manual.

I am listening to F5 (the music is Tchaikovsky performed by Wiener Philharmoniker and von Karajan) and realizing that it is so good that if this was my first amplifier, I might not be interested in building anything else.

Update: after a year, this is still the best amplifier.

Update: I purchased the official F5 PCBs from the diyAudio store. I will rebuild the amplifier, hopefully with better FETs and other parts.
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Old

NOS TDA1541A double crown

Posted 27th January 2012 at 05:54 PM by dvb projekt
Updated 30th November 2016 at 09:23 AM by dvb projekt

I am a lucky man!

I´ve got two NOS TDA1541A double crown DAC´s from a friend



Click the image to open in full size.

He bought the last from Philips a long time ago...


Just now i swapped them on my Red Baron modules...

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What could i say.... They will never leaving the DAC modules again !!!




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Old
Rating: 2 votes, 4.50 average.

First Watt F5 Amp build

Posted 27th January 2012 at 02:53 PM by dvb projekt
Updated 13th November 2015 at 10:32 AM by dvb projekt (New photo source)

After reading so much over this amp, i will start a new project for my Hornspeaker

Let´s see if the F5 can play in the same league as my 300B mono´s



The parts


Click the image to open in full size.

Schaffner FN 2070 - 3A multistage EMI Filter


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Antek AS-4218 - 400VA transformer



Click the image to open in full size.

SST03 Softstart module from Sjostrom Audio
Design without extra transformer


Click the image to open in full size.

RFB03 rectifier bridge from Sjostrom Audio

Click the image to open in full size.

with IXYS DPG 60 C 200 HB
...
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Old

Whither Next for RJM Audio?

Posted 26th January 2012 at 01:22 AM by rjm (RJM Audio Blog)
Updated 1st February 2012 at 09:20 AM by rjm

On the occasion of selling the 100th and last VSPS Stereo Kit, it's time to consider what direction(s) RJM Audio will take over the next little while.

A. A minor revision of the stereo VSPS board is planned. Just a point release to address feedback I received over the last couple of years. Point release on current boards (Phonoclone 3, VSPS 300, Sapphire) expected when I deplete existing stock and have to re-order.

B. Since my circuit designs are essentially modular (the voltage regulation of the Sapphire headphone amp could be used with the Phonoclone, the output stage of the Sapphire could be detached and used on the output buffer on the VSPS...) I'm going to work on bringing that vision to a concrete reality by developing "swap-in swap-out" circuit boards... like those toys where you can change out the head, body and legs of a character to make many variations.
  1. X-reg board
  2. Zener reg board
  3. basic op amp gain block board
  4. VSPS and
...
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Old

My system (Jan 2012)

Posted 23rd January 2012 at 01:12 PM by rjm (RJM Audio Blog)
Updated 26th January 2012 at 03:57 AM by rjm

Biggest changeover in many years.

Denon DP-2000, DA-307, DL-103 turntable/tonearm/cartridge
Phonoclone 3 with 160 VA Plitron power supply
47 Labs "Treasure" model 0247 preamplifier
47 Labs "Treasure" model 0347 amplifier
Onkyo D-605SR speakers
Cables by oyaide, mostly.
(photo: Pentax K10D, Pentax FA 31mm F1.8 AL Limited)
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Old

Oh, MY!

Posted 23rd January 2012 at 07:51 AM by rjm (RJM Audio Blog)

Denon DL-A100

Transparent DL-103 for Denon's 100th anniversary.
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Old

op amps for audio

Posted 23rd January 2012 at 07:36 AM by rjm (RJM Audio Blog)

Douglas Self on op amps for audio, which I read before in slightly different form, on another web site somewhere, many years ago... today was a refresher course.

Excerpts from op amps in small signal audio design, by D. Self [Part 1, part 2, part 3, part 4].

I suppose I should get with the times and start using the LM4562 seeing as it is available in DIP8 now. (I had this memory that it was only SOIC, go figure...) Pity it's dual only. On the other hand, that leads to some neat ideas, like a compact version of the Sapphire amp for example, or the X-reg.

I am struck by how few choices we really have when it comes to practical op amps for audio in single DIP8 packages. There is the NE5534, TL071 and TL051, the OPA134, the OPA604, and OPA27, OPA627. Maybe the AD797 but I have yet to see the point. Given that the TL1071 and derivatives are outdated and replaced essentially by the OPA134, and given the excessive cost (and questionable sonic benefit)...
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Old

Anyone notice parallels here with Intel?

Posted 23rd January 2012 at 01:25 AM by abraxalito
Updated 23rd January 2012 at 01:27 AM by abraxalito

Could Kodak's demise have been averted? | Technology | The Observer

My best bet for why Kodak is history comes towards the end of this relatively short piece:

More insightful analyses point to the fact that Kodak had a near-monopolistic grip on a market that was giving it a 70% margin on its products and processes, and that therefore the people who ran the film part of the business were the ones who carried most weight in corporate discussions.
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Old

Bt schematic

Posted 22nd January 2012 at 04:59 PM by klewis
Updated 23rd January 2012 at 01:19 AM by klewis

http://www.diyaudio.com/forums/solid...lifier-86.html
Pavel's scheme http://www.diyaudio.com/forums/solid...ifier-103.html
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Old

The new system, up and running.

Posted 22nd January 2012 at 11:52 AM by rjm (RJM Audio Blog)
Updated 25th January 2012 at 08:57 AM by rjm

So now we have the model 0247 DAC/preamp/headphone amplifier and model 0347 power amplifier in the main system. That's the old Denon DP-2000 TT, Phonoclone 3, and Onkyo D-605SR speakers.

The gain of the 0347 is 30 dB, so with the 0247 doing duty as a preamp the overall gain is a tad high, but it's perfectly useable. I'll look at the passive preamp options (including the model 0447) at a later date.

Anyhow, the big news is it completely destroys the non-inverting LM3875 Gainclone I have been using for the last decade, so badly, in fact, I'm starting to wonder if my Gainclone was busted. In comparison with the 0347 it sounds like a distorted, uncontrolled mess.

Since my speakers are really very modest in quality (though at 82dB and 6 ohms, a bit of a rough load) I wasn't expecting much difference one way the other, so this comes as a severe shock.

Unfortunately I'm not within reach of a good reference system to give the 0347 a real evaluation....
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