diyAudio - Blogs http://www.diyaudio.com/forums/blogs/ A community dedicated to helping everyone learn the art of audio. Projects by fanatics, for fanatics! en Sun, 12 Feb 2012 12:21:22 GMT vBulletin 60 http://cdn1.dastatic.com/forums/images/diy/misc/rss.jpg diyAudio - Blogs http://www.diyaudio.com/forums/blogs/ Converting Eagle printed circuit board layout files to Gerber format http://www.diyaudio.com/forums/blogs/rjm/833-converting-eagle-printed-circuit-board-layout-files-gerber-format.html Sat, 11 Feb 2012 00:20:40 GMT File this under "things-I-should-have-learnt-to-do-many-years-ago-but-was-too-lazy-to-bother".

Many pcb fab outfits that do business with hobbyists and DIYers choose to accept Eagle .brd files, which means they do the conversion to Gerber output so you don't have to. I've relied on that for far too long, but when an error showed up in one the .pdf proofs on the last batch of boards I sent out for fabrication, they asked me to send the Gerber files instead. So I bit the bullet and after a couple of false starts managed to give them what they wanted. Looking back at it, it was easy and something I should have learnt, as I wrote up above, years ago, but, for posterity, here's how it's done:

(In Eagle 6.1, on Windows Vista)
  1. Make a working folder for the Gerber files.
  2. Copy the Eagle board (.brd) file to this directory.
  3. Open Eagle (version 6.1)
  4. Select menu item "file/open/CAM job"
  5. The open file dialog appears, defaulting to the Eagle CAM directory. Open the file called "gerber.cam". The CAM Processor window now appears
  6. From the CAM Processor windows select menu item "file/open/board" and open the .brd file you copied to the directory in step 2.
  7. Click on the "Process Job" button. There is a short progress bar, maybe a warning about having more than one signal active.
  8. A bunch of 8 new files are created in the working folder. As prompted, you should delete the temp file which ends in .$$$
  9. OK, almost done. You still need to make the drill files. From the CAM Processor window, choose "file/open/job" and select "excellon.cam"
  10. Click on the Process Job button again, and 2 new files are created, .drl and .drd
  11. Delete, if you like, the original Eagle .brd file from the working folder. You should be left with 9 files (.cmp .drd .dri .gpi .plc .sol .stc .sts and .whl) Select them, and, on Windows at least, choose to add to a zip compressed archive.
  12. That's it, you're done. The archive is ready to be sent off to the board manufacturer.

Probably. I'm not an expert. It's what I did and I was told by the receiving party that all was present and correct.

Any comments and corrections would be welcome. ]]> rjm http://www.diyaudio.com/forums/blogs/rjm/833-converting-eagle-printed-circuit-board-layout-files-gerber-format.html Audio op amp comparison NE5534A vs. OPA134 http://www.diyaudio.com/forums/blogs/rjm/832-audio-op-amp-comparison-ne5534a-vs-opa134.html Fri, 10 Feb 2012 23:49:55 GMT Finally got around to some more comparison listening with the Sapphire (http://phonoclone.com/diy-sapp.html) headphone amplifier. To recap: the... Finally got around to some more comparison listening with the Sapphire headphone amplifier. To recap: the circuit has an open loop diamond buffer output, so the op amp is just providing voltage gain. It configured for a non-inverting gain of 21 dB to match my 300 ohm HD600 headphones. Pretty much textbook operating conditions.

The op amp inputs are impedance balanced at about 1 kohm. This is about the crossover point where you start thinking about using FET input stages, but BJTs should still be fine.

I'm interested to see if there is a definite signature to a FET-input opamp. The original build called for an OPA134, which is a JFET input circuit. I tried the OPA27, which is a low-noise, high-input-current BJT design, and last night I tried the NE5534A, a classic general purpose audio opamp with bipolar inputs.

I've long been in agreement with Douglas Self on the NE5532/NE5534 : anyone who reports these op amps sound bad is either not using them correctly, or is just being a snob. As cheap and generic as this IC is, it also happens to sound just fine. Really good, actually.

So yes, I could distinguish a difference in the sound of the three op amps I tested: OPA134, OPA27, and NE5534A.

First, the OPA27, which I did not feel sounded as good as the other two here. Music sounded a bit constrained, deadened sense of dynamics, very little air. A bit rough even.

Next the OPA5534A, which I thought was the most neutral and precise of the three. Solid, clean, perhaps a bit "bloodless", but never anything less than faithfull.

That leaves the OPA134, the FET op amp that I am still undecided on. I will say this: I love the way it sounds. It's airy, deep, hugely 3D... but there is this nagging doubt that it's adding a little extra in there. In direct comparison with the NE5534A it seems very slightly sloppy, less solid, and a bit over-accentuated at the top end. ]]> rjm http://www.diyaudio.com/forums/blogs/rjm/832-audio-op-amp-comparison-ne5534a-vs-opa134.html RJM Z-reg + Pass B1 http://www.diyaudio.com/forums/blogs/rjm/831-rjm-z-reg-pass-b1.html Sat, 04 Feb 2012 00:53:34 GMT I was asked to suggest a voltage regulator for the First Watt (Pass DIY) B1 buffer (http://www.passdiy.com/pdf/B1%20Buffer%20Preamp.pdf). One thing... I was asked to suggest a voltage regulator for the First Watt (Pass DIY) B1 buffer. One thing led to another and the next thing I'd sketched up a circuit board for the buffer as well as the regulator.

It's like a B-board, but with the JFET buffer instead of the diamond buffer, and with a single supply and, hence, the coupling caps front and back. Since it's using JFETs for the buffer I used a JFET for the pass device in the regulator, too.

Full credit to Nelson Pass for his design.

Eagle files do not show 2SK170 because the package is not in Eagle. All transistors 2SK170 or equivalent. Zener is 18-22V DO35 or DO41 i.e. Vishay BZX85. V++ is 5-15 V above whatever you select the Zener reference to be.
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]]> rjm http://www.diyaudio.com/forums/blogs/rjm/831-rjm-z-reg-pass-b1.html The Z-reg http://www.diyaudio.com/forums/blogs/rjm/829-z-reg.html Wed, 01 Feb 2012 23:58:23 GMT This is a followup of sorts to the X-reg (http://phonoclone.com/diy-xreg.html), though there is nothing original about the circuit this time around.... This is a followup of sorts to the X-reg, though there is nothing original about the circuit this time around.

It's just a Zener voltage regulator with a series pass transistor. I lifted this particular configuration from the Pionner C-21 preamplifier and re-tuned it for op amp applications. My main interest here is trying to make a small and convenient board layout.

I've used this circuit block already in the Sapphire amp and come away impressed.

The output is about 1 V less than the Zener voltage, and the input voltage should be about 3-6 V above the Zener reference voltage. I'm working here with 17 V unregulated supply and 12 V Zeners, but the values can be reconfigured easily enough for any output from 4-24 V

This is a low current circuit. If you are just powering a few op amps, no heatsinks are needed. Above 25 mA small heatsinks are a good idea. The circuit is not designed for output currents above 100 mA.
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]]> rjm http://www.diyaudio.com/forums/blogs/rjm/829-z-reg.html Current Feedback Amplifier http://www.diyaudio.com/forums/blogs/rjm/828-current-feedback-amplifier.html Tue, 31 Jan 2012 06:15:16 GMT Found this today: DC Coupled Amplifiers for Audio (http://www.andiha.no/articles/audio/dcamp.htm) from an 11 year old web page by one Knut Harald... Found this today: DC Coupled Amplifiers for Audio from an 11 year old web page by one Knut Harald Nygaard.

I've taken some minor liberties with the circuit, shown in the second, color image below. Replaced the current sources with resistors and moved the output buffer out of the feedback loop.

Note the resultant double symmetry of the dual-diamond buffer topology, highlighted in blue.
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]]> rjm http://www.diyaudio.com/forums/blogs/rjm/828-current-feedback-amplifier.html Protoamp project. http://www.diyaudio.com/forums/blogs/digitaljunkie/827-protoamp-project.html Sun, 29 Jan 2012 20:52:53 GMT So,I've been pondering this for a while,and I'm going to finally build it.

Basic idea- Fairly simple Push-Pull amplifier,that will deliver ~50Wpc,Using common/available tubes.
I decided to go with the 'usual' octals,since they are all a similar basing/pinout(7ac?).
This leaves us open to use 6L6,EL34,6550,KTxx,etc. for output tubes.
We'll have to have a -Vg1 supply with a wide voltage range to cover the needs of all those tubes,shouldn't be a problem.

The power transformer is a big 1kva/500W beast,used in the Tektronix 545A. (P/N 120-120)
Pete Millett was kind enough to post some data on this transformer,and a few others here:
Tek power transformers

The output transformers are rated ~100W,they came from a pair of old RCA MI-12188A amps.
They are ~3.5-4.0K (p-p) primary impedance.
There is some information on these amplifiers/transformers here:
The Shrine of the Ancient and Most Excellent RCA MI-12188A Power Amplifier

I'm thinking I might want to incorporate George's 'Powerdrive' setup in this amp.
I have two main thoughts behind this.
First, it gives our input tube(s) a nice high impedance to drive - we won't have to worry as much about whether it has enough drive for the chosen output tubes.
Second,It will be able to drive whatever output tubes we can fit in the output 'holes',without breaking a sweat.
All we need to do is make sure our driver can swing enough voltage.

To fit the kind of modular/prototype theme,I'm going to use a ST-70 board as a driver. This way we can use the original Dynaco circuit/board,or one of the many other "upgrade" boards available. We can even spin our own custom boards/circuits to experiment with.


Here's the power supply schematic,as viewed from my mind's eye. Some values and things are just kind of ballpark/placeholders for now.
http://i199.photobucket.com/albums/a...CHEMATIC-2.png

And here's the basic amp schematic,again some values and things are just kind of ballpark for now.
http://i199.photobucket.com/albums/a...utputStage.png


A couple of questions,

I need to find some MOSFET's to use for the source followers,any thoughts on FET's that are currently available?

Also,I'm wondering about the +V supply for the source followers. Since I'm not planning on driving the grids very far positive (though,it could happen) would it be okay to lower the +V for the source followers,to help lower dissipation? Right now I'm thinking of using something like a +/-150V supply. Could I maybe swap that for,perhaps, +12V and -150V supplies?

I'm sure I'll have more to ramble about later..but for now,any thoughts? ]]> DigitalJunkie http://www.diyaudio.com/forums/blogs/digitaljunkie/827-protoamp-project.html F5 http://www.diyaudio.com/forums/blogs/alexcp/826-f5.html Sat, 28 Jan 2012 18:39:48 GMT 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... 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. ]]> alexcp http://www.diyaudio.com/forums/blogs/alexcp/826-f5.html NOS TDA1541A double crown http://www.diyaudio.com/forums/blogs/dvb-projekt/825-nos-tda1541a-double-crown.html Fri, 27 Jan 2012 17:54:13 GMT *I am a lucky man! Iīve got two NOS TDA1541A double crown DACīs from a friend :D Image: http://img401.imageshack.us/img401/7285/sam1096.jpg ...
I am a lucky man!

Iīve got two NOS TDA1541A double crown DACīs from a friend

:D



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


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



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

:worship:


 ]]> dvb-projekt http://www.diyaudio.com/forums/blogs/dvb-projekt/825-nos-tda1541a-double-crown.html First Watt F5 Amp build http://www.diyaudio.com/forums/blogs/dvb-projekt/824-first-watt-f5-amp-build.html Fri, 27 Jan 2012 14:53:31 GMT *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...
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




Schaffner FN 2070 - 3A multistage EMI Filter





Antek AS-4218 - 400VA transformer





SST03 Softstart module from Sjostrom Audio
Design without extra transformer




RFB03 rectifier bridge from Sjostrom Audio



with IXYS DPG 60 C 200 HB HiPerFRED diodes





PSU with Mundorf 22.000ĩF/40V M-Lytic AG caps
and Mills MRA05 resistors







diyaudio amp pcb with
PRP PR9372 & Mills MRA05 resistors
For R9, R13 & R14 witch are in the signal line, i choose Texas Components TX2575 resistors.
For P1 & P2 i choose Vishay 1240 bulk metal foil pots, ordered also at Texas Components.



Here is the design for the 3U front and back









The mechanical work



The transformer, rectifier bridges, soft start module and EMI Filter are on their places




Just a quick look with the psu in the 2nd floor

:)




Starting internal cabling with Kimber TCX cable.




Fitting test on the heatsink


Stay tuned!





 ]]> dvb-projekt http://www.diyaudio.com/forums/blogs/dvb-projekt/824-first-watt-f5-amp-build.html Whither Next for RJM Audio? http://www.diyaudio.com/forums/blogs/rjm/823-whither-next-rjm-audio.html Thu, 26 Jan 2012 01:22:35 GMT 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 Phonoclone boards with no voltage regulation.
  5. Diamond buffer board. (configurable for headphone, preamp, or line buffer use)
  6. Power buffer board. Unity gain transistor output stage for power amplifier. More of a long term project, concept only at this point.

All the boards will be standardized as much as humanly possible, same size and mounting, using common resistor values, etc, so a minimum number of different parts are required, and if you collect the parts for one project, you can re-use most of them on another one.

[update]

After thinking it over, the fundamental problem with the approach is the more general purpose and granular you make the modules, the bigger and more complicated the total circuit becomes: instead of one circuit board and four standoffs, you have four, and a dozen or more chassis holes to drill and a similar number of extra interconnects.

It makes more sense, I think, it to develop the modular circuit blocks, but put them together in common combinations when making a circuit board. ]]> rjm http://www.diyaudio.com/forums/blogs/rjm/823-whither-next-rjm-audio.html My system (Jan 2012) http://www.diyaudio.com/forums/blogs/rjm/822-my-system-jan-2012.html Mon, 23 Jan 2012 13:12:32 GMT Biggest changeover in many years. Denon DP-2000 (http://denon.jp/jp/museum/products/dp2000.html), DA-307 (http://speaker.kir.jp/cm-to/da-307.htm),... 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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]]> rjm http://www.diyaudio.com/forums/blogs/rjm/822-my-system-jan-2012.html Oh, MY! http://www.diyaudio.com/forums/blogs/rjm/821-oh-my.html Mon, 23 Jan 2012 07:51:43 GMT Denon DL-A100... Denon DL-A100

Transparent DL-103 for Denon's 100th anniversary.
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]]> rjm http://www.diyaudio.com/forums/blogs/rjm/821-oh-my.html op amps for audio http://www.diyaudio.com/forums/blogs/rjm/820-op-amps-audio.html Mon, 23 Jan 2012 07:36:07 GMT 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... 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) of the OPA627, and given the rather nondescript performance and suspect "black box" design of the OPA604, one is basically left with NE5534 for general work, OPA134 for high impedance, low input current applications (following volume controls) and the OPA27 for phono stages and low noise, low impedance work preferably in the inverting circuit topology.

For dual DIP8 packages, NE5532 or LM4562, and for FET input, OPA2134. ]]> rjm http://www.diyaudio.com/forums/blogs/rjm/820-op-amps-audio.html Anyone notice parallels here with Intel? http://www.diyaudio.com/forums/blogs/abraxalito/819-anyone-notice-parallels-here-intel.html Mon, 23 Jan 2012 01:25:31 GMT 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. ]]> abraxalito http://www.diyaudio.com/forums/blogs/abraxalito/819-anyone-notice-parallels-here-intel.html Bt schematic http://www.diyaudio.com/forums/blogs/klewis/818-bt-schematic.html Sun, 22 Jan 2012 16:59:55 GMT http://www.diyaudio.com/forums/solid...lifier-86.html
Pavel's scheme http://www.diyaudio.com/forums/solid...ifier-103.html ]]> klewis http://www.diyaudio.com/forums/blogs/klewis/818-bt-schematic.html