TDA2004 Bridge configuration, distortion/2nd harmonic?
- Chip Amps
- 82 Replies
Hello,
Recently started a little project where i needed a decent speaker output, so started researching some chip-amp designs.
I landed on a TDA2004 which was readily available from my "local" electronic store. Using the 2005 datasheet for the bridge configuration (the tda2004 datasheet does not have any, but cant really find reason why).
I attach the schematics from the datasheet for reference. Only thing i changed from it was adding a 10k log pot on the input, and using 56ohms instead of 12 to lower the gain somewhat. Should end up at about 38db instead.
I'm very happy with the sound from it, it turned out perfect for my project. Its enough fidelity, hehe.
However, of course I could not let it be, so I found some videos online about using FFT functionality of a oscilloscope to check distortion.
I got interested in this, not mainly for checking the amp as I know there are tons of other checks that needs to be done and as I said, I was happy with the sound.
I just wanted to try out FFT on the scope, as I have never used it before.
I got everything setup and using a .wav file with a 1% distortion added just to check that I'm able to catch that, and I was successful.
However, I did notice that I have a distortion on the 2khz that is about the same %. Now, it is not in fact the added distortion that is playing tricks here. That distortion is always present, no matter if i choose another 1khz "clean" file or even a function generator.
Did some reading, and I think "crossover" distortion can show up like this. So is this the reason? Can it be fixed on a amp like this? Or maybe is it even expected? I see that there is 1% distortion in the datasheet specs, but not sure if this is what they mean with that.
Please see the spectrum analyzer screenshot and the circuit attached.
Any ideas or other intel is greatly appreciated!
Recently started a little project where i needed a decent speaker output, so started researching some chip-amp designs.
I landed on a TDA2004 which was readily available from my "local" electronic store. Using the 2005 datasheet for the bridge configuration (the tda2004 datasheet does not have any, but cant really find reason why).
I attach the schematics from the datasheet for reference. Only thing i changed from it was adding a 10k log pot on the input, and using 56ohms instead of 12 to lower the gain somewhat. Should end up at about 38db instead.
I'm very happy with the sound from it, it turned out perfect for my project. Its enough fidelity, hehe.
However, of course I could not let it be, so I found some videos online about using FFT functionality of a oscilloscope to check distortion.
I got interested in this, not mainly for checking the amp as I know there are tons of other checks that needs to be done and as I said, I was happy with the sound.
I just wanted to try out FFT on the scope, as I have never used it before.
I got everything setup and using a .wav file with a 1% distortion added just to check that I'm able to catch that, and I was successful.
However, I did notice that I have a distortion on the 2khz that is about the same %. Now, it is not in fact the added distortion that is playing tricks here. That distortion is always present, no matter if i choose another 1khz "clean" file or even a function generator.
Did some reading, and I think "crossover" distortion can show up like this. So is this the reason? Can it be fixed on a amp like this? Or maybe is it even expected? I see that there is 1% distortion in the datasheet specs, but not sure if this is what they mean with that.
Please see the spectrum analyzer screenshot and the circuit attached.
Any ideas or other intel is greatly appreciated!
Voltage Display Replacement (DSN-DVM-368) on Zero Zone LPS-25?
- By MrJohn
- Power Supplies
- 2 Replies
Hi All,
I bought my Linear Power Supply secondhand. I opened it up and if the name on the board is indicative of the maker, it looks like it's a Zero Zone LPS-25. The voltage display has been dying for some time and I would like to replace it but I'm having some difficulty finding it. Anyone have one of these? DSN-DVN-368 v3.01.
I am definitely a novice when it comes this stuff, but my soldering skills are pretty decent. I used to mess around with R/C cars and I've built a couple ACAs, although I don't really comprehend everything I am doing since it's basically like a paint by number type of build).
At some point, I would like to learn enough to build one of these Linear Power Supplies myself and this display replacement is a start right? Any help is appreciated. Thank you!
* Alos, any tips of removing what looks to be hot glue?
I bought my Linear Power Supply secondhand. I opened it up and if the name on the board is indicative of the maker, it looks like it's a Zero Zone LPS-25. The voltage display has been dying for some time and I would like to replace it but I'm having some difficulty finding it. Anyone have one of these? DSN-DVN-368 v3.01.
I am definitely a novice when it comes this stuff, but my soldering skills are pretty decent. I used to mess around with R/C cars and I've built a couple ACAs, although I don't really comprehend everything I am doing since it's basically like a paint by number type of build).
At some point, I would like to learn enough to build one of these Linear Power Supplies myself and this display replacement is a start right? Any help is appreciated. Thank you!
* Alos, any tips of removing what looks to be hot glue?
Interest for another Omicron group buy
- By alexcp
- Group Buys
- 17 Replies
UPDATE 03/24/2025: this GB is now closed.
After the third Omicron group buy closed in June last year, there has been a number of requests for more boards, so I'd like to see if there is interest for another group buy for:
If you're interested in any of these boards, please sign up below before end-of-day Sunday, March 23 by replying to this thread. Copy the list of those interested into your post and add your own line as follows:
(1) Your name here on diyAudio -- (2) Omicron TH board, pieces -- (3) Omicron SMT bare board, pieces -- (4) Omicron PSU board, pieces -- (5) Omicron DC protection boards, pieces, -- (6) Country to ship the board(s) to.
Try to preserve formatting.
Additional information
The following four boards (bare, unpopulated, parts not included) are offered in this GB, in any quantity you want and in any combination:
What it is
(1) Your name here on diyAudio -- (2) TH board, pieces -- (3) SMT bare board, pieces -- (4) PSU board, pieces -- (5) DC protection boards, pieces, -- (6) Country to ship the board(s).
Try to preserve formatting.
Running List for Subscription:
YourNameNere -- 1 -- 1 -- 1 -- 1 -- USA
This group buy will close on Sunday, March 23, 2025. Be sure to sign up before then.
After the third Omicron group buy closed in June last year, there has been a number of requests for more boards, so I'd like to see if there is interest for another group buy for:
- Omicron through-hole board;
- Omicron SMT board;
- Omicron power supply board;
- Omicron headphone protection board (which is not necessary for the Omicron itself, as the same protection is already included, but which may be used with other headamps).
If you're interested in any of these boards, please sign up below before end-of-day Sunday, March 23 by replying to this thread. Copy the list of those interested into your post and add your own line as follows:
(1) Your name here on diyAudio -- (2) Omicron TH board, pieces -- (3) Omicron SMT bare board, pieces -- (4) Omicron PSU board, pieces -- (5) Omicron DC protection boards, pieces, -- (6) Country to ship the board(s) to.
Try to preserve formatting.
Additional information
The following four boards (bare, unpopulated, parts not included) are offered in this GB, in any quantity you want and in any combination:
- Omicron through-hole PCB: a 80x110mm, two-sided board that carries two amplification channels, optional crossfeed, DC protection circuit, and the output filter. All parts are through-hole and regular sized, so the board is fairly easy to build despite its compact layout.
- Omicron SMT PCB: a 60x90mm, two-sided board that carries two amplification channels, relay-switchable crossfeed, DC protection circuit, and two output filters (one for headphones, one for line output). The board itself serves as a heatsink for the output stages. Most parts are SMT, but no parts are smaller than 1206 or SOT-23, so this board is also reasonably easy to solder by hand.
- Omicron power supply PCB: a 130x80mm, two sided PCB that carries an AC mains filter, 230/115VAC mains voltage selector, a power transformer, a pair of regulators, and an quick-turn-off circuit that works together with Omicron's DC protection. This board is optional - you can power Omicron from other suitable power supplies - but it has been tested in multiple builds and works well with the Omicron.
- Omicron DC protection PCB: a 50x50mm, two sided PCB that carries a copy of Omicron's DC protection. This board is not needed to build the Omicron, which already includes the same DC protection circuit, but may be used with other headamps. The quick-turn-off of this protection works together with Omicron's power supply board.
What it is
- Omicron is a compact, inexpensive and easy to build headphone amplifier with very musical, pure, clean, liquid sound and perfect clarity even in the most harmonically complex pieces. As one of the first GB participants put it, "The clarity is surreal."
- Designed to work with 32 to 600 ohm headphones and tested with a range of over-the-ear and on-the-ear cans from AKG, Beyerdynamic, Grado, Klipsch, and Sennheiser as well as with lower impedance 16 and 8 ohm headphones, such as AKG's K3003 3-way in-ear monitors; even white Apple EarPods (tethered ones, both 1st and 2nd generation) sound great with Omicron, too!
- Ultra low distortion; at -140dBc, Omicron is an order or two more linear than other "high-performance" and "ultra-high performance" headamps. Omicron adds neither dirt nor fairy dust, offering exceptional clarity and fluidity of sound. With Omicron and a good pair of cans, music just carries you away. And if you want to look at the measurements, we have them, too.
- Simple and inexpensive to build. One channel of Omicron is built with just one dual opamp, two transistors, ans a bunch of resistors and capacitors. The circuit allows broad opamp substitution and has been tested to work well with many modern (e.g. OPA1642) and not-so-modern (NE5532) opamps. At the time of the first GB, the total cost of parts to build one Omicron board (two channels) was just $42.
- Built-in fast (10ms) and sensitive (80mV DC) headphone protection.
- Built-in optional cross-feed circuit, helping to create a more realistic soundstage.
- Compact and easy to build.
- $5 per one protection board, $15 per any other one board, plus shipping.
- Shipping is calculated at checkout. U.S. Postal Service offers inexpensive shipping to the continental U.S. starting at $3.80 (USPS Ground Advantage) with tracking or $1.60 (USPS First Class Mail) without. International shipping (USPS First Class International Package) will cost somewhere between $16 and $20, depending on the destination. Should you want to buy something else from me, I of course can combine shipping.
- The main thread has lots of details, including full schematics, part lists, board outlines, assembly instructions, and more. The first post in the main thread includes a list if links to most useful posts. I will review the thread in the coming days and update it as needed.
- The DC protection has its own thread.
- Part lists aka BOMs has been published for each board. I will update the BOMs over the next couple of weeks making sure all parts are available and any errors and omissions discovered so far are corrected.
- We support Omicron builders in the main thread.
(1) Your name here on diyAudio -- (2) TH board, pieces -- (3) SMT bare board, pieces -- (4) PSU board, pieces -- (5) DC protection boards, pieces, -- (6) Country to ship the board(s).
Try to preserve formatting.
Running List for Subscription:
YourNameNere -- 1 -- 1 -- 1 -- 1 -- USA
This group buy will close on Sunday, March 23, 2025. Be sure to sign up before then.
The F5 Preamp 2024
As already mentioned earlier in the F5Pi thread, we have all the ingredients that will also make a nice Preamp.
It has taken much longer than we wanted, but it is finally playing music since yesterday.
www.diyaudio.com/community/threads/the-f5pi-f5p-voltage-gain-stage-m2-output-stage-perfectly-integrated.406024/post-7524606
www.diyaudio.com/community/threads/the-f5pi-f5p-voltage-gain-stage-m2-output-stage-perfectly-integrated.406024/post-7538379
www.diyaudio.com/community/threads/the-f5pi-f5p-voltage-gain-stage-m2-output-stage-perfectly-integrated.406024/post-7741027
As always, I don't comment on subjective sonic impressions.
I'll leave it to Fran to tell you what he thinks, when he has enough hours on it.
Happy reading,
Patrick
.
It has taken much longer than we wanted, but it is finally playing music since yesterday.
www.diyaudio.com/community/threads/the-f5pi-f5p-voltage-gain-stage-m2-output-stage-perfectly-integrated.406024/post-7524606
www.diyaudio.com/community/threads/the-f5pi-f5p-voltage-gain-stage-m2-output-stage-perfectly-integrated.406024/post-7538379
www.diyaudio.com/community/threads/the-f5pi-f5p-voltage-gain-stage-m2-output-stage-perfectly-integrated.406024/post-7741027
As always, I don't comment on subjective sonic impressions.
I'll leave it to Fran to tell you what he thinks, when he has enough hours on it.
Happy reading,
Patrick
.
Attachments
Transformer suited for MC step up?
- By profiguy
- Analogue Source
- 1 Replies
I have a set of these Jensen transformers and was curious if they would be useful for MC step up with a low output MC cartridge?
The winding and DCR ratios suggest a possible good fit for MC step up. Aside from shielding and FR linearity, is there anything else I'm missing from the equation which would define these transformers as being a good fit for purpose?
If this transformer isn't a good fit, does anyone have other good suggestions for reasonably priced, decent MC step up transformers which would play nice with low to medium output MCs? I'm running both the AT OC9/II and an older VDH MC cart. Both are low output units.
The winding and DCR ratios suggest a possible good fit for MC step up. Aside from shielding and FR linearity, is there anything else I'm missing from the equation which would define these transformers as being a good fit for purpose?
If this transformer isn't a good fit, does anyone have other good suggestions for reasonably priced, decent MC step up transformers which would play nice with low to medium output MCs? I'm running both the AT OC9/II and an older VDH MC cart. Both are low output units.
voltage doubler switching noise
- By emartine
- Tubes / Valves
- 13 Replies
Hello. I am using this for my preamp heater circuit:
I also connect that the output to an LM555 timer that activates a relay and all sort of jazz.
the thing is that i get some mishaviours because of this turn on noise:
if I switch it off and turn on again, looks like this, and everything works flawlessly:
any idea on how to reduce that noise?
is this because of the voltage doubler?
the diodes inside the BR310?
may be transformer inrush current?
THANK YOU!
I also connect that the output to an LM555 timer that activates a relay and all sort of jazz.
the thing is that i get some mishaviours because of this turn on noise:
if I switch it off and turn on again, looks like this, and everything works flawlessly:
any idea on how to reduce that noise?
is this because of the voltage doubler?
the diodes inside the BR310?
may be transformer inrush current?
THANK YOU!
Adcom gfa-5200 with slope of the square wave in the bass range
- By birnstingl
- Solid State
- 3 Replies
Attachments
Burson Supreme Sound V6 Classic Opamp Upgrade for Music Hall 25.2 DAC
I just received some V6 Classics from Carlos at Burson/Supreme Sound. I reached out after seeing a thread on DiyAudio about offering samples and wanting to step my Music Hall 25.2 DAC up a notch or two. Big Thank You!
My Music Hall 25.2 DAC and ph25.2 Headphone Amp have been my daily companions while I work from home during the pandemic so they have been getting 6-8 hours of use daily and I feel I've become very accustomed to how they sound. Everything is stock aside from replacing the stock Electro-Harmonix tube on the 25.2 DAC with a Gold Lion.
Tube swapping was a great cheap and easy inexpensive upgrade for this DAC. The Electro-Harmoni stock tube is what I consider to be on the neutral and dry side. The Gold Lion adds a touch more warmth and romance and an additional sense of spaciousness.
So far I have about +- 20 hours of listening to the V6 Classics which replaced 2 X OPA2134 and 1X OPA2604.
One of the criticisms of this DAC is that it can sound a little rolled off and isn't the most revealing. For me, it's one of the reasons I like it. Prior to the Pandemic, I was mostly a vinyl/analog listener and really only used digital to search out new music on streaming services or on my daily commute to work. Since buying this DAC, I've pulled my CD collection out of mothballs and picked up a decent transport.
While this isn't a review of the DAC, the description of its character it is important because the biggest change I noticed right off the bat is the V6 Classic opamps brought so much more detail retrieval and openness to the sound that I was very surprised what I had been missing all along. I've been mostly listening with AudioQuest NightHawks and NightOwls and I find them to be a great example of the differences between the stock opamps and the Bursons. The V6 Classic is similar to the NightHawks in the sense that it's more open sounding with a bigger soundstage and a bit more even bass response, where the stock opamps are more like the NightOwls being more intimate and more bass-heavy.
Overall, I would easily recommend this upgrade for users of the 25.2 or 25.3 DAC. While it may seem like a steep investment for a $599 piece of equipment, it really takes what is already an overachieving product up to a new level. You can spend allot more and get allot less as they say!
Since swapping is so easy with this equipment, I'm going to give the V6 Classics some more listening time and then reinstall the stock opamps and report back.
My Music Hall 25.2 DAC and ph25.2 Headphone Amp have been my daily companions while I work from home during the pandemic so they have been getting 6-8 hours of use daily and I feel I've become very accustomed to how they sound. Everything is stock aside from replacing the stock Electro-Harmonix tube on the 25.2 DAC with a Gold Lion.
Tube swapping was a great cheap and easy inexpensive upgrade for this DAC. The Electro-Harmoni stock tube is what I consider to be on the neutral and dry side. The Gold Lion adds a touch more warmth and romance and an additional sense of spaciousness.
So far I have about +- 20 hours of listening to the V6 Classics which replaced 2 X OPA2134 and 1X OPA2604.
One of the criticisms of this DAC is that it can sound a little rolled off and isn't the most revealing. For me, it's one of the reasons I like it. Prior to the Pandemic, I was mostly a vinyl/analog listener and really only used digital to search out new music on streaming services or on my daily commute to work. Since buying this DAC, I've pulled my CD collection out of mothballs and picked up a decent transport.
While this isn't a review of the DAC, the description of its character it is important because the biggest change I noticed right off the bat is the V6 Classic opamps brought so much more detail retrieval and openness to the sound that I was very surprised what I had been missing all along. I've been mostly listening with AudioQuest NightHawks and NightOwls and I find them to be a great example of the differences between the stock opamps and the Bursons. The V6 Classic is similar to the NightHawks in the sense that it's more open sounding with a bigger soundstage and a bit more even bass response, where the stock opamps are more like the NightOwls being more intimate and more bass-heavy.
Overall, I would easily recommend this upgrade for users of the 25.2 or 25.3 DAC. While it may seem like a steep investment for a $599 piece of equipment, it really takes what is already an overachieving product up to a new level. You can spend allot more and get allot less as they say!
Since swapping is so easy with this equipment, I'm going to give the V6 Classics some more listening time and then reinstall the stock opamps and report back.
For Sale Vendetta Research SCP2C
Legendary phono amp in perfect condition. All electrolytics have been replaced. Im the second owner. See photos for the cosmetic condition.
Not many C models have been made, so pretty rare.
2850€ + shipping
Located in Finland
-Antti
Not many C models have been made, so pretty rare.
2850€ + shipping
Located in Finland
-Antti
Tube clipping nube question
- By Rupopulles
- Tubes / Valves
- 10 Replies
Hi All,
I'm LTspicing my first tube amp dablings. 300B fantasies. I noticed the following:
When the input signal on the grid exceeds the cathode voltage, the 300b output tube clips.
On the 12ax7 input tube however, the grid signal does swing past the cathode voltage. Which is correct? Is this supposed to happen or is this a modeling discrepancy?
Probably common sense to you. Yet I haven't found the answer. Perhaps you would like to point me to the obvious truth. Thank You!
Kind regards,
Ruben
I'm LTspicing my first tube amp dablings. 300B fantasies. I noticed the following:
When the input signal on the grid exceeds the cathode voltage, the 300b output tube clips.
On the 12ax7 input tube however, the grid signal does swing past the cathode voltage. Which is correct? Is this supposed to happen or is this a modeling discrepancy?
Probably common sense to you. Yet I haven't found the answer. Perhaps you would like to point me to the obvious truth. Thank You!
Kind regards,
Ruben
minicrescendo elektor pcb
- By scafas
- Vendor's Bazaar
- 0 Replies
trying to resurrect an Orion 2150GX after massive short
- By spartaco02
- Car Audio
- 32 Replies
Attachments
For Sale Bruel & Kjaer - Vintage Microphone Amplifier Type 2603
Attachments
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2603 ready to ship.jpg
The Photography and Camera Thread
I thought it would be nice to have dedicated thread to talk about cameras and such.
To start things off…
On a whim, I bought a $17 manual focus C-mount lens with M4/3 adapter for my LUMIX GX-1. It’s 35mm focal length which gives 70mm equivalent FOV in 35mm format. I wasn’t expecting much, but the lens arrived and it’s nicely built all metal (black anodized aluminum) and laser engraved markings with butter smooth operation. Multi coated lens elements, a round 12 blade aperture. When I installed it on the camera - it instantly transformed the feel and how you take pictures - because both aperture and focus are now mechanical rings and you have to use it just like the old school manual film cameras. I left the camera on aperture priority and applied compensation when needed. Test shots showed nice sharpness wide open at F/1.6 (although very narrow plane is in focus) and superb narrow depth of field to isolate the subject. Nice bokeh - smooth tonality in out of focus regions. Color rendition is excellent. I don’t see any light falloff even wide open. I did not expect it to work so well, frankly. Here are some test shots in the lab. I’m a happy camper. This is a nice portrait lens and it’s going to add another dimension to manual shooting. Damn amazing for $17!
Highly recommended! They make adapters for other camera formats. I chose M4/3 for mine. Here is the one I got. It even comes with two threaded C mount spacer rings to allow macro photography.
Lens looks like this with adapter:
Mounted on the camera it’s quite compact for a short telephoto:
Here is a closeup photo wide open, note the tight depth of field and smooth out of focus regions:
Farther away and still wide open (look at the text on the driver handles):
Color rendition is nice - very accurate:
I can’t wait to use this to take candids or on the street.
The main thing is that it brings back the muscle memory of using my old film cameras. Instead of holding to my eye, I look at the screen to focus. My camera has a magnifier patch to check focus.
To start things off…
On a whim, I bought a $17 manual focus C-mount lens with M4/3 adapter for my LUMIX GX-1. It’s 35mm focal length which gives 70mm equivalent FOV in 35mm format. I wasn’t expecting much, but the lens arrived and it’s nicely built all metal (black anodized aluminum) and laser engraved markings with butter smooth operation. Multi coated lens elements, a round 12 blade aperture. When I installed it on the camera - it instantly transformed the feel and how you take pictures - because both aperture and focus are now mechanical rings and you have to use it just like the old school manual film cameras. I left the camera on aperture priority and applied compensation when needed. Test shots showed nice sharpness wide open at F/1.6 (although very narrow plane is in focus) and superb narrow depth of field to isolate the subject. Nice bokeh - smooth tonality in out of focus regions. Color rendition is excellent. I don’t see any light falloff even wide open. I did not expect it to work so well, frankly. Here are some test shots in the lab. I’m a happy camper. This is a nice portrait lens and it’s going to add another dimension to manual shooting. Damn amazing for $17!
Highly recommended! They make adapters for other camera formats. I chose M4/3 for mine. Here is the one I got. It even comes with two threaded C mount spacer rings to allow macro photography.
Lens looks like this with adapter:
Mounted on the camera it’s quite compact for a short telephoto:
Here is a closeup photo wide open, note the tight depth of field and smooth out of focus regions:
Farther away and still wide open (look at the text on the driver handles):
Color rendition is nice - very accurate:
I can’t wait to use this to take candids or on the street.
The main thing is that it brings back the muscle memory of using my old film cameras. Instead of holding to my eye, I look at the screen to focus. My camera has a magnifier patch to check focus.
VRDN PSU fully built and working
- Swap Meet
- 3 Replies
Two VRDN boards for sale, fully working as I used them for my DAC.
Asking EUR 30 each or EUR 50 for both plus shipping to The Netherlands.
Asking EUR 30 each or EUR 50 for both plus shipping to The Netherlands.
Bryston 4B-SST clone kit for sale, $ 80 plus the shipping cost
- By gaetan8888
- Swap Meet
- 1 Replies
Attachments
Dark LED passive filter-I/V stage for NOS DACs
- By abraxalito
- Vendor's Bazaar
- 185 Replies
Orders now are open on 'Dark LED' passive filter/IV stage boards, ready built and tested or as a kit for the baseboard with a pre-built and tested filter plug-in. PM me and please don't forget to include your chosen payment method and location so I can quote you inclusive of fees and shipping.
'Dark LED' combines a grounded base (discrete) cascoded stage followed by a 9th order LC filter, then passive I/V followed by a single-ended output buffer, designed to deliver lowest noise. The LC filter does the job of removing DAC images which, when in NOS (no oversampling) begin at 24.1kHz where this filter gives 40dB attenuation. Input sensitivity is +/1mA for 1VRMS out. The grounded base input stage presents a very low impedance to your DAC chip's current output (typically of the order of 5ohm) which helps it give of its best.
Here is how an 18kHz sinewave looks on a typical very-lightly filtered NOS DAC, compared to the filtered output of 'Dark LED' reproducing the same signal :
Preferred payment method is via Wise which typically adds a 2% fee. Our receiving currency is CNY, alternatively USD or Euro. PayPal may also be used, in USD but will attract higher fees, 5.5%.
Price for a Dark LED built and tested unit including top-mounted filter board : 920RMB (~USD128)
A kit with most SMD parts pre-soldered at JLC, filter plug-in pre-built : 720RMB (~USD100)
Physical dimensions: 72mm * 65mm, max height 25mm. Fixing centres : 60mm * 60mm, M3 holes.
Shipping is in addition and depends on your location and speed of service. Courier (FedEx, TNT, DHL) typically takes 8 - 10 days and e-packet four to eight weeks. Not all locations can be serviced by e-packet though.
FAQs
What else is needed to turn the built up Dark LED filter-I/V stage into a fully operational DAC?
You'll need, as a foundation, an existing DAC with a current output, +/1mA R2R chip. A few examples of suitable DAC chips are PCM56, PCM61, AD1860, AD1865 and PCM1702, these all have +/-1mA output in Iout mode. Your base could be an existing DAC board where you wish to bypass its on-board I/V (perhaps a socketed opamp) or maybe just a lash-up on perf-board with your R2R chip of choice. If your chosen DAC chip includes an opamp, be sure that this isn't in-circuit and the input to 'Dark LED' is being taken from the Iout pin of the DAC chip. With a socketed single opamp I/V the DAC Iout can usually be taken from pin2 (-ve input) of the socket when the opamp's removed.
Next you'll need a well regulated low noise power supply of dual rail +/-18V rated at 100mA or higher. An LM317 and LM337-based board set to the correct output voltages will be the bare minimum noise-wise. If you already have a single winding AC supply (an AC wall-wart) then 18VAC at 10-20VA would be in the right ballpark. Use a half-wave rectifier so you get both rails from a single winding or alternatively, a centre-tapped trafo. I don't recommend using switching supplies due to issues with common-mode noise, its very hard to filter out.
Third you'll be wanting some output sockets, typically RCAs so you can connect your Dark LED I/V to your amp or preamp. But your existing DAC may already have these, fed from its own filter stage.
What will I have left to solder if buying the kit version?
The parts JLC hasn't soldered are three NP0 capacitors, several 0.1% thin film resistors, ferrite beads (all 0805 size), SOT-89 transistors, 7mm dia inductors and the through-hole parts which are electrolytic caps and connectors.
What, if anything, is unique about Dark LED's design?
The LC filter is hand-built with in-house wound close tolerance gapped ferrite cored inductors, selected NP0 ceramic caps and the rest of the circuitry uses discrete (bipolar and MOS) transistors to deliver as low noise as possible. To this end, an SE (single-ended) approach is taken with I/V. The name 'Dark LED' comes from the use of infra-red LEDs as voltage references, which are very low noise indeed.
The use of IR LEDs helps reduce intrinsic and power-supply coupled noise meaning that a heroic ultra-low noise PSU isn't required, LM317/337 deliver satisfying results sonically at around 20uV audio band noise. Some technical background to the design can be found on my blog : https://www.diyaudio.com/community/threads/i-v-stages-and-noise.391189/post-7146239
'Dark LED' combines a grounded base (discrete) cascoded stage followed by a 9th order LC filter, then passive I/V followed by a single-ended output buffer, designed to deliver lowest noise. The LC filter does the job of removing DAC images which, when in NOS (no oversampling) begin at 24.1kHz where this filter gives 40dB attenuation. Input sensitivity is +/1mA for 1VRMS out. The grounded base input stage presents a very low impedance to your DAC chip's current output (typically of the order of 5ohm) which helps it give of its best.
Here is how an 18kHz sinewave looks on a typical very-lightly filtered NOS DAC, compared to the filtered output of 'Dark LED' reproducing the same signal :
Preferred payment method is via Wise which typically adds a 2% fee. Our receiving currency is CNY, alternatively USD or Euro. PayPal may also be used, in USD but will attract higher fees, 5.5%.
Price for a Dark LED built and tested unit including top-mounted filter board : 920RMB (~USD128)
A kit with most SMD parts pre-soldered at JLC, filter plug-in pre-built : 720RMB (~USD100)
Physical dimensions: 72mm * 65mm, max height 25mm. Fixing centres : 60mm * 60mm, M3 holes.
Shipping is in addition and depends on your location and speed of service. Courier (FedEx, TNT, DHL) typically takes 8 - 10 days and e-packet four to eight weeks. Not all locations can be serviced by e-packet though.
FAQs
What else is needed to turn the built up Dark LED filter-I/V stage into a fully operational DAC?
You'll need, as a foundation, an existing DAC with a current output, +/1mA R2R chip. A few examples of suitable DAC chips are PCM56, PCM61, AD1860, AD1865 and PCM1702, these all have +/-1mA output in Iout mode. Your base could be an existing DAC board where you wish to bypass its on-board I/V (perhaps a socketed opamp) or maybe just a lash-up on perf-board with your R2R chip of choice. If your chosen DAC chip includes an opamp, be sure that this isn't in-circuit and the input to 'Dark LED' is being taken from the Iout pin of the DAC chip. With a socketed single opamp I/V the DAC Iout can usually be taken from pin2 (-ve input) of the socket when the opamp's removed.
Next you'll need a well regulated low noise power supply of dual rail +/-18V rated at 100mA or higher. An LM317 and LM337-based board set to the correct output voltages will be the bare minimum noise-wise. If you already have a single winding AC supply (an AC wall-wart) then 18VAC at 10-20VA would be in the right ballpark. Use a half-wave rectifier so you get both rails from a single winding or alternatively, a centre-tapped trafo. I don't recommend using switching supplies due to issues with common-mode noise, its very hard to filter out.
Third you'll be wanting some output sockets, typically RCAs so you can connect your Dark LED I/V to your amp or preamp. But your existing DAC may already have these, fed from its own filter stage.
What will I have left to solder if buying the kit version?
The parts JLC hasn't soldered are three NP0 capacitors, several 0.1% thin film resistors, ferrite beads (all 0805 size), SOT-89 transistors, 7mm dia inductors and the through-hole parts which are electrolytic caps and connectors.
What, if anything, is unique about Dark LED's design?
The LC filter is hand-built with in-house wound close tolerance gapped ferrite cored inductors, selected NP0 ceramic caps and the rest of the circuitry uses discrete (bipolar and MOS) transistors to deliver as low noise as possible. To this end, an SE (single-ended) approach is taken with I/V. The name 'Dark LED' comes from the use of infra-red LEDs as voltage references, which are very low noise indeed.
The use of IR LEDs helps reduce intrinsic and power-supply coupled noise meaning that a heroic ultra-low noise PSU isn't required, LM317/337 deliver satisfying results sonically at around 20uV audio band noise. Some technical background to the design can be found on my blog : https://www.diyaudio.com/community/threads/i-v-stages-and-noise.391189/post-7146239
Attachments
Ideal bridge rectifier GB
- By iTiberius
- Group Buys
- 539 Replies
I had a look on the market, did not find one, so we built one. 🙂
We have designed a small form synchronous rectifier, aka ideal bridge, using modern ultra low Rdson mosfets.
It started as a small side project, but the results are so good that we want to put this in production and make it a standard product.
The advantages of such bridge are very well documented:
Active rectification - Wikipedia
http://www.ti.com/lit/wp/snva595a/snva595a.pdf
Synchronous Rectifier Circuit | Active Rectifier | Radio-Electronics.Com
http://peufeu.free.fr/audio/alim_mos_diode/
Linear product presentation.
https://www.youtube.com/watch?v=x74SSPgKiNA
While this video is about automotive product, the principle is similar.
https://www.youtube.com/watch?v=X5qFJ5XNi9A
Specifications:
- operates from DC to 600Hz
- AC operating voltage 6Vac to 51Vac
- DC operating voltage 9Vdc to 72Vdc
- Iq = 1,5mA
- continuous load current up to 16A or more depending on mosfet configuration.
Do not use centre taped transformers (and centre taped used as main reference ground).
The price will start from 35euro and go down with volume as we get parts in lower price.
Up to 100 units - 35 euro
Up to 200 units - 30 euro
Over 200 units - 25 euro
GB google spreadsheet is open till 1st March included
https://docs.google.com/spreadsheets/d/144EP7ZezFLFgZeNq8q8LCgoa5Lb6z94TKbopFC7S6aw/edit?usp=sharing
Regards,
Tibi
3 Way DSP Amp
I assembled the following revision of the light version of the board, three channels of 100W PWM DAC with DSP ADAU1452.
Since there were some changes to the board structure, I decided to create a new topic to avoid confusion. Description of the previous version of the board here.
On this board revision, I add three auxiliary ADC inputs and two discrete input/output ports from the DSP. This expands the possibilities of external control of the chipboard.
To coordinate the operation of the ESP32 module and the DSP via the I2S port, a clock frequency detection circuit was implemented on the I2S bus; this was done to eliminate the transient process when receiving I2S data.
An ESP32 module was added to the optical input/output board to implement wireless audio transmission via Wi-Fi and Bluetooth.
Starter projects for Sigma Studio.
Since there were some changes to the board structure, I decided to create a new topic to avoid confusion. Description of the previous version of the board here.
On this board revision, I add three auxiliary ADC inputs and two discrete input/output ports from the DSP. This expands the possibilities of external control of the chipboard.
To coordinate the operation of the ESP32 module and the DSP via the I2S port, a clock frequency detection circuit was implemented on the I2S bus; this was done to eliminate the transient process when receiving I2S data.
An ESP32 module was added to the optical input/output board to implement wireless audio transmission via Wi-Fi and Bluetooth.
Starter projects for Sigma Studio.
3Way DSP Amp + adapter for Dante AES67 board.
Aliexpress sells the Audio Network Transmission Interface A404 module, which supports the DANTE data transfer protocol.
The A404 module can be connected to the 3-Way DSP Amp using the adapter I assembled.
This solution, using Dante software, allows you to transmit two stereo channels to the 3-Way DSP Amp via the Ethernet.
The price of the 3Way DSP Amp + adapter board without the DT AES67 module is $105.
Attached to the post is an archive of a folder with files for the starter project for Sigma Studio.
The A404 module can be connected to the 3-Way DSP Amp using the adapter I assembled.
This solution, using Dante software, allows you to transmit two stereo channels to the 3-Way DSP Amp via the Ethernet.
The price of the 3Way DSP Amp + adapter board without the DT AES67 module is $105.
Attached to the post is an archive of a folder with files for the starter project for Sigma Studio.
Salas Folded Simplistic Phono (2014)
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Tried unusual output stage with great results
- By Radian
- Digital Line Level
- 48 Replies
Hi guys I have to share my unscientific experiment.
I got bored in my hotel room so I thought I try something crazy.
I pulled the opamps out of my Chinese R2R DAC and also out of my Accuphase c-3850 preamp clone boards from Ali that normally use NE5534 on the input.
Took some wires that fit nicely into the opamp sockets and connected all in in/out fashion.
Result is very good. Dynamic detailed spacious sound.
All is powered by the Jan Didden silent switcher that runs off a 5v power bank. It puts out positive and negative 15v for the Accu boards and 5V for the Dac itself.
Listened for about 2 hours with only using up 1 bar of four from my 10a/h power bank.
I used my phone with USBplayer pro in bit perfect mode.
Absolutely stunning without any expensive opamps involved.
Gain is very high but for road use I will put the volume pot between the two Accuphase clone boards
If I use my tube amp I can probably get away with using only one Accuphase board.
I got bored in my hotel room so I thought I try something crazy.
I pulled the opamps out of my Chinese R2R DAC and also out of my Accuphase c-3850 preamp clone boards from Ali that normally use NE5534 on the input.
Took some wires that fit nicely into the opamp sockets and connected all in in/out fashion.
Result is very good. Dynamic detailed spacious sound.
All is powered by the Jan Didden silent switcher that runs off a 5v power bank. It puts out positive and negative 15v for the Accu boards and 5V for the Dac itself.
Listened for about 2 hours with only using up 1 bar of four from my 10a/h power bank.
I used my phone with USBplayer pro in bit perfect mode.
Absolutely stunning without any expensive opamps involved.
Gain is very high but for road use I will put the volume pot between the two Accuphase clone boards
If I use my tube amp I can probably get away with using only one Accuphase board.
Bridged amplfier circuit help
- By Angel23
- Solid State
- 11 Replies
I've wanted to build a bridged amplifier as a project for a while, so I decided to first simulate a schematic in LTSpice. However, I got really weird results. The first channel looks fine, but on the second, the waveform doesn’t go as low as the first channel (I’m not sure how to explain it better), and the top is heavily distorted. Also, when using the Fourier function, the first channel gets around 0.003148% THD, while the second one is around 0.4–0.5%.
Also in lt spice simulation, i used the universal op amp 5 if that matters.
Here is an image:
The green wave is the 2nd channel and the blue the first.
Heres the schematic:
Also in lt spice simulation, i used the universal op amp 5 if that matters.
Here is an image:
The green wave is the 2nd channel and the blue the first.
Heres the schematic:
