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NOS TDA1541A double crown

Posted 27th January 2012 at 05:54 PM by dvb projekt

I am a lucky man!

Iīve got two NOS TDA1541A double crown DACīs from a friend



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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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Rating: 2 votes, 4.50 average.

First Watt F5 Amp build

Posted 27th January 2012 at 02:53 PM by dvb projekt
Updated 8th January 2014 at 08:17 PM by dvb projekt (Project finished)

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

Letīs see if the F5 can play in the same league as my 300B monoīs



The parts


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Schaffner FN 2070 - 3A multistage EMI Filter



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Antek AS-4218 - 400VA transformer



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SST03 Softstart module from Sjostrom Audio
Design without extra transformer


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RFB03 rectifier bridge from Sjostrom Audio

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with IXYS DPG 60 C 200 HB HiPerFRED diodes



...
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Whither Next for RJM Audio?

Posted 26th January 2012 at 01:22 AM by rjm
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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My system (Jan 2012)

Posted 23rd January 2012 at 01:12 PM by rjm
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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Oh, MY!

Posted 23rd January 2012 at 07:51 AM by rjm

Denon DL-A100

Transparent DL-103 for Denon's 100th anniversary.
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op amps for audio

Posted 23rd January 2012 at 07:36 AM by rjm

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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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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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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The new system, up and running.

Posted 22nd January 2012 at 11:52 AM by rjm
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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Sony SA H7900, motional feedback active speakers

Posted 21st January 2012 at 11:42 AM by hbc

Following my "conversion" that valves really do sound better than transistors:

http://www.diyaudio.com/forums/solid...c-project.html

My home stereo, which is compromised by having to be small person resistant, has been in a state of flux. I worked out that the most economical tube fix was to by a receiver from ebay, so I got a 1967 ish one, 17 tubes, push pull EL84s etc, it is original and it works, but the RIAA is way, out the FM stereo decoder needs re alignment, and all the output tubes share a common cathode resistor, 2 ECC83s in series.... so it went on the bench and has stagnated... also most of my speakers don't really suit it.


So to fill the gap I thought I would drag out a pair of Sony SA H7900 active speakers I acquired about 8 years ago, not just active, motional feedback woofers and electrostatic tweeters no less, and bass reflex(?) what could possibly go wrong?


When...
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