Hello Guys,

Now I am planning the DSP-integrated Power Amplifier Board Project.
Current ideas are two variations ...

• FreeDSP INTEGRA Duo (ADAU1466 + TAS6422) Stereo Speaker Output
• FreeDSP INTEGRA Quad (ADAU1466 + TAS6424) 4ch Speaker Output

For starters, now I'm working on a 2ch version prototype design. The intention was to install the Full-Range/2-way boombox enclosure.
But this can be a single-board solution for desktop audio systems...



Input

• RCA Analog
• Optical S/PDIF
• Coax S/PDIF or AES/EBU
• USB (Amanero Combo384)
• Raspberry-pi Zero W/2W

Control

• AUX POT x1 (for DSP)
• Source Selector (TBD)
• Rotary Encoder x1 (for Power-Amp)
• A push-button or clickable Rotary Encoder
• 3digits LED Display
• PIC16F18346 MPU

Output

• Speaker Output x2 (Duo), x4(Quad)
• Optical S/PDIF

Power Supply

• 2.5mm Center 5.5mm Sleeve Wall Power Adaptor or 24V 4A PSU
• Screw Terminal for Power Switch

CyberPit

I have a Bryston 2B-LP that I bought new in the US in 1987. I've moved overseas and back with it a couple of times. While using it overseas, I always had it plugged in to a step-down transformer.

It recently occurred to me that I might be able to convert it for 230V by rewiring its two transformer primaries in series. That's sort of what restrappable transformers do, except, here, there are two separate cores, so, if the current draw of one channel was significantly higher, it would probably tend to sag more, since the other transformer would have more back EMF and be dropping more of the supply voltage. Is that a real concern, or does this plan sound reasonable? BTW it ran fine for years off of 50Hz 120V, so I'm not too concerned about the frequency.

Orders now are open on Dorati NOS DAC kits - PM me and be sure to include your payment method and location so I can quote you inclusive of fees and shipping. Dorati offers a sound quality upgrade over its predecessor 'Kubelik' but retains the same physical footprint of 81mm * 50mm, slightly smaller than a credit card; the maximum height is 24mm. The design is non-oversampling (i.e. there's no digital filter on-board) uses passive I/V and has a discrete output stage. What sets it apart from typical NOS DACs is the use of an LC filter prior to the active stages. The input format is I2S (three signal wire) at 44k1/16bits. BCK can be 1.4 or 2.8MHz, no MCK is required. Output is CD standard 2VRMS and headphones at 300ohm impedance and above can be directly driven. Power supply requirement is a single 12-15V rail at 150mA max. There's a digital invert function, selectable by a 0R resistor. Schematic may be found here : Dorati schematic updated 6.23
Dorati can be used in a pair of boards to create a balanced output DAC. To achieve this you'll also need an I2S splitter board which is sold separately. The splitter changes the normal L,R stereo configuration of I2S into two outputs: L+,L- and R+,R-.

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, about 6%.

Price for a Dorati kit : 168RMB (~$25)
I2S splitter board to create balanced output DAC : 90RMB

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 Dorati kit into a fully operational DAC?

First you'll need a well regulated low noise power supply of 12 - 15V rated at 150mA or higher. An LM317-based board set to the correct voltage will suffice if you already have an unregulated supply (like a typical wall-wart). I don't recommend switching supplies due to issues with common-mode noise, its very hard to filter out. This dis-recommendation though only applies if you're building a stand-alone DAC. If you are building the Dorati into a system with the amps in the same box then switching supplies are perfectly fine but I would then recommend an LC filter to reduce the switcher's output ripple, a direct connection is likely to reduce SQ. We can supply an LM317-based board with either DC (for unregulated DC) or AC (for a transformer) input option. LC filters for SMPSUs are on the drawing board as I write this, best enquire if they've become available.

Second you may need a digital interface card. I say 'may' because some digital sources produce I2S directly (like Raspberry Pi, many dedicated SDcard players) but most sources will either output USB (like a PC or laptop) or S/PDIF coax (a CD or DVD player) or Toslink. We can supply a card for interfacing one (or more) of those sources to Dorati's I2S input. A CM6631A-based card for USB input is the premium choice as it operates under 'async USB' which is the lowest jitter. A mid-range alternative is an interface based on an STM32F4 microcontroller - while still low jitter, its output is not as clean on start/stopping as with CM6631A. TE7022 is another suitable USB controller chip in the mid-range bracket. In the bargain basement dept are the interfaces based on 'adaptive USB' such as CM108 and PCM270X.

There's an advantage in going for a USB interface that operates on full-speed USB (12Mbits) rather than high-speed (480Mbits). That is - you can buy a cheap isolator device to use with it and isolation from your PC's common-mode noise is most definitely worth having from a SQ point of view. 480Mbit isolators have recently become available but are much more expensive (price ratio in the region of 10:1 compared to 12Mbits). For my DACs I have come to the conclusion that isolation is more valuable than ultimate lowest jitter. Full-speed USB interfaces only go up to 96k sample rate so if you're someone who needs 192k then look out for a high-speed isolator.

The S/PDIF board we recommend handles both coax (two inputs) and Toslink. Further, it has a switched I2S input - this is useful to accept an I2S stream from a separate USB interface card to facilitate a USB input. A single pole switch acts as source selector, cycling through the four sources. An OLED screen is an option to indicate the selected input. If your DAC supply is 12V, you can directly power this card from the same supply as you use to feed the DAC. The simple coax/Toslink board needs a regulated 5V PSU which can be implemented via a regulator from the DAC supply.

Third you'll be wanting some output sockets, typically RCAs so you can connect your finished DAC to your amp or preamp. Or if you're feeding high impedance HPs, a 6.3mm (or 3.5mm) TRS socket. We can supply these. We also have a PCB for mounting a pair of RCAs which makes connection a little easier.

Lastly, and this is obviously optional for a DIYer, is a case. We haven't supplied cases in the past because they're so heavy (i.e. expensive to ship).

Whilst these links all worked when I posted, Ali links go stale very quickly so beware. CM6631A is rapidly becoming unobtainium, we couldn't find a single Taobao seller with stock :

USB CM6631A card examples : Aliexpress CM6631A USB-I2S
USB STM32 card example : Aliexpress STM32USB card
USB TE7022 card example : Aliexpress TE7022 USB interface
USB PCM270X card example : Aliexpress PCM2706 USB interface
USB full-speed isolator example : Aliexpress USB full-speed isolator
USB high-speed isolator example : Aliexpress USB high-speed isolator
Multi-input S/PDIF card : Aliexpress S/PDIF Toslink I2S switcher
Coax/Toslink S/PDIF card : Aliexpress DIR9001 S/PDIF receiver

Do I need special tools to build and test my Dorati kit?

You'll need some fine diameter solder (0.3mm is recommended), a temperature controlled soldering iron with a fine bit and a pair of tweezers. A magnifier comes in very handy but that depends on your eyesight. Desoldering braid is helpful for correcting mistakes. If you've never soldered SMD before then maybe Dorati will be too challenging for a first project as there are around a hundred parts. However none of them are microscopic (the smallest is 0805) and none of the ICs has pins closer together than 1.27mm. For testing you'll need a DMM (digital multimeter).


What's supplied in the kit?

There's a picture directly below of the contents (to be added) : the bare PCB plus all the components that mount on it (resistors, caps, inductors, LED, ICs etc.). Given that 0805 sized components are incredibly easy to lose, we include a spare or two for each value. Input, output and power are supplied via 4pin Molex-style headers, we supply the mating half with crimped wires to these too.


What, if anything, is unique about Dorati's design?

Commercial NOS DACs typically have minimal filtering after the DAC chip itself. Dorati has two kinds of filters resulting in a 5th order overall lowpass response - a 3rd order passive filter prior to I/V and a 2nd order active filter afterwards. The passive filter prior to any active stage improves subjective dynamics - it means the I/V buffer no longer 'sees' a step waveform out of the DAC chip, rather a continuous signal. The active filter provides 'NOS droop' compensation - meaning you get a flat frequency response to around 17kHz whereas a typical (not every) NOS DAC has roll-off approaching 3dB by 20kHz. No opamps are used, the analog signal processing stages are all discrete transistors. Dorati's DAC chips are 'multibit' but they're not strictly speaking 'R2R' as internally they use no resistors. Instead capacitors are used as elements in the DAC which have their charge constantly refreshed (similar to the DRAM in your computer) to compensate for any drift.

Hello, I just had a problem today with the Across Audio by Chywen Bryston 4b clone boards.. I already done this clone a few times in the past (4B sst clone from Across Audio by Chywen Rev5) in the past and it work fine. But recently I've burn three boards back to back when trying to adjust bias to 20mv on R45. It start to burn when reaching about 10 mv. All the positive ramp destroyed... Did somebody find the solution or the cause of this problem ?
I saw that somebody that had the same problem in a post. (Fetamp)
Thanks

SOLD

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Where can I find a service manual for the Cayin 251b amplifier?

Hey guys,

I would appreciate some ideas based on your experience.

I am playing now with Rotel RSX-1058. There is no sound coming out of this receiver.
1) It powers up, there is a working communication between the main MCU and the front panel MCU as well as with the volume control & input selection ICs (I verified that they work)
2) The MCU keeps the output stage of the preamp in mute
3) The MCU keeps the DSP in reset state, therefore the sound goes through (if we forget mute=on) only in 'Bypass' mode, where the DSP is not used.
4) All the supplies seem OK
5) Both the MCU and the DSP oscillators are working fine

It's not hugely common receiver but based on your experience with perhaps some other devices - any ideas what typically goes wrong?




Thanks!

Unused, in sealed box. Two pairs available.
Paypal, Free Shipping.
100euro/pair

Hi, I want to build a high quality single input line level valve pre to partner my quad 303 amps.

I've built elekit kits before which i really like, but they only offer a pre with included phono stage etc which i don't need.

If they built a cheaper single or double input pre without phono i would buy it.

Are there any tried and tested simple designs or kits that would cover what i am after?

Thanks for any suggestions.

Hoping to try soldering VQFN package TPS7A regulators using this very cheap mini hotplate, reviews on the tube seem ok just for single small PCBs.

Any one have experience with hotplates like these?

Also recommendations for 138 C paste and no clean flux, leadfree is the main option it seems at the temp range.

Evening ladies and gents, Austin here, new to the forum and introducing myself. Love me some vintage equipment but definitely a beginner/novice. Electrician by trade with basic electronic skills.

I have an old, old NAD 304 integrated amp which I bought on my grad student budget years ago and guess what, I am still using it with a NAD 512 CD player.

A while ago the 304 started loosing signal at low levels. It fades one channel at a time, at first it was just the left channel, now it's both. The fading in two channels isn't simultaneous. It occurs more often after a few minutes of playing, rather than when the amp's just turned on.

Sometimes I hear intermittent problem that sounds like a bad wire contact, i.e. "scratchy".

Checked all wire connections, headphone output doesn't have the same problem. What could it be and what should I check/replace?

Hello everyone,

Long time reader, but finally got in.

Hello,

as I am fond of making loudspeakers out of marble I thought a thread with stone / concrete / marble boxes could be fun and inspiring for anyone who wants to use these box building materials.

https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7536566

I seen this today on YouTube advertised by GR research

YouTube

It will be my first open baffle build I’ve been curious about one and for the price as a starter kit it seem too good to pass up. My last speaker I built was the BK 20 Fostek package kit I built for my ACA. That was kind of complex folded horn speaker to build took about 100 hours from start to finish.

The X-Statik looks like a simple easy inexpensive build minimum woodworking skill easy finishing. I keep having to put off my alpha J build but I was thinking of using the speakers with the Alpha J.

I used the search tool bar to see if I could find a thread on “ X-Statik “ nothing turned up. Does this mean I use the wrong search term ? Or the speaker wasn’t good enough to make it on DIY Audio Forms ?.

Anybody with experience please chime in and tell me what I’m in for when I complete this project will it be a keeper or give away as a gift ?.

I've been working on a variation of the JLH symmetric headphone amplifier that is designed to address one of its original problems, which is the relatively large values of emitter resistors needed to get the auto-bias circuitry working. The thought occurred to me that the emitter resistor values could be greatly reduced if an additional current was extracted/injected from/into the base connection(s) of the current-regulating transistors. This would, in essence, add an offset to the base voltage so the output transistors' emitter resistors could be reduced in value.

First pass results (i.e., not worrying about drift due to temperature variations) looked pretty good but the circuit's phase margin wasn't very good. The JLH design is interesting because if you place capacitors between the output node and the input transistors' emitter you get something like this:



Not shown: the version here is using .5 ohm resistors on the output transistor's emitters, much smaller than the original JLH design..

Given the phase response plot now the subject line of my post should be clear. Feed-forward, pole-zero, however you want to classify it, those driver transistors plus the capacitors work a treat.

For a 1KHz input, a 0 dB fundamental on this circuit's output has a 2nd harmonic level that's about 120dB down from the fundamental. Not surprising, considering the high OLG of the OPA1656. I'm pretty happy that the amp is stable despite the huge overall gain. At least in simulation. The output transistors' idle current is about 140mA for that result. The rails are +/-15V

Here's a screenshot with the AC feedback loop restored:

Its bandwidth is WAY too high for my taste -- it's just asking for oscillation problems due to external parasitic coupling. But that's easy enough to address.

Just to repeat, I haven't checked to see how this approach works over temperature. The bias-control loop gain is lower compared to the original JLH design (due to the lower Re) so I certainly don't expect it to be better. But, given the fact that the bias control transistors' input dynamic resistance has to be the same as in the original JLH design (since their emitter currents are the same), maybe not enough of a difference to matter.

These are all simulations so real-world results will almost certainly be worse. However, I'm encouraged because the (simulated) transistors on the + and - sides are different in terms of device parameters, yet producing that level of distortion.

I have to say that I'm not all that crazy regarding the way the driver transistors are operated (w/regard to their emitter resistors' load voltages). It's a way to ensure relatively poor PSRR. There are relatively easy ways to address it, and I have already designed/built a variation on the original JLH HA that does just that -- using +/- 4V voltage regulators.

Hello, I've been a reader here for a long time. I work (diy) on power amplifiers and make PCBs using Eagle. I am a retired electronics engineer (technician in germany ).

A few year's ago I learned all about the magic sound of the TDA 1541a Chip. As a result I purchased a Marantz PM75 amplifier as I needed an amp. But this was one of few machines at that time ( circa 1989/90 ) which has a DAC. And that DAC contains a Silver Crown TDA1541 chip. It sounds really good and I have since had all the capacitors replaced with Kemit ones. To my mind it is underrated and given that chip it is very good value for money to buy second hand.

Fast forward and I decided to upgrade my DAC. I was going down the Chord route (having also got a Hugo2) , but I had a epiphany moment when I decided to stick to old fashioned multibit technology and so decided to purchase a Marantz DAC ie D12, Project D1 or a CDA 94. The latter came up recently for purchase , which had been upgraded with black gate capacitors and better opamps. It does sound fantastic. There is a depth and holographic feel to the bass that is very appealing to hear.

I also wanted to upgrade the TDA1541A chip and have been successful ...... and I have a simple "technical" question in that regard to ask here.

Hey thanks for membership and for running this community, i look forward to share and develop knowledge.
Iam a big fan of the old transistor based consoles especially Neve 80 series consoles and the sound of them, I have nerded out on designing my own modules and now I want to take it a little further and use some of my old 1:12 transformers, to make a mic preamp. but with a transistor amp.
Iam looking for transistor based schematics for mic preamp that can use a 1:12 winding input transformer. If it has ever been made. I know a 1:12 ratio winding would be made for tube amps. But I wonder if anyone back in the days 60’S/70’S made any mic pres in consoles for that type of transformer, that was transistor based. Or also someone nowadays who made it would be of interest.
Let me hear if you heard about such thing or what your thoughts are on the idea.

Kind regards Bob

Hi,

Glad to be a new member of DIY audio.
Im a French Sound Engineer student from Paris and I want to discover the world of diy audio (speakers & later synths)
I will post soon to ask advices on my DIY speaker 2.1 Bluetooth project so hope you will have good recommandations 🙂

Thx
Léo

The pitfalls of AB testing are centered around how our brain works. During the normal day to day operation of the brain it has to map stimuli to a labeled branch of knowledge that means it collapses similar branches to one branch. If it has already heard a sound and then hears a distorted version of that sound it will map the distorted sound to the cleaner sound. That means when AB testing amplifiers that are different, the difference may only be heard the first time. On the second run the amplifiers will sound similar on the same sound track. Does that mean AB testing is impossible and unnecessary? As can be seen in these results here, these amplifiers are different in performance but the brain will correct up to 15% error so that they sound similar, the more correction applied the more pleasant as the brain is replaying the recorded familiar sound rather than the live amplifier sound.

Thanks for accepting me the site.

I assembled this Ian Canada streamer - the flagship compact #93B. It's come together very well - super easy to put together and sounds absolutely divine in my chain. However, it does look like a Mars lander - which I don't mind, but my family is not a fan of (the kit is in my living room), and I do worry about electrocuting some curious visitor who starts poking the super-caps.

Looking for experiences and advice on putting this in a case. One option would be to just build or buy a case into which this can go as it is - as a vertical stack. The other option would be to flatten it and put some of the boards across with ribbons connecting the GPIOs. Am ok with the mains brick outside - just need the main stack inside the case.

If anyone has built a 3D printed case for the whole stack, would love to get the designs ... or other ideas also welcome.

A 2.5 way basreflex loudspeaker floorstander with crossover was tested.

Multiple measurements are consistent and only differ at first impedance peak. 1 Ohm difference. ..Allways... what does this mean? Resister measurements outcomes between the 2 measure methods are the same.
Resister measurements that were done showed expected values and are within range for both methods.

Comparison measurement DATSv3 versus DATSv3 + REW

DATSv3 + REW Red
DATSv3 Purple

In REW all values except “the leads resitance value” for the impedance setup were take from the manual DATv3 on a Mac written by olen.

10kΩ for the Rsense value. (based on the value of output resistor) Don’t know my Dats R value

Set Rsense = 10kΩ

100kΩ for Rin (where is this value derived from?)

10mΩ for Rleads. I used 0.7399 Ohm Messured earlier with dats sofware.

For the reference cal I used a 4.952 ohm resistor..

-- INFO -- My version of the DATSv3 is different from olen’s...See earlier post with picture...If my dats series output resistor value differs say 2000 Ohm from the 10000 in olens Manual could that alter the reponse, and then ONLY doing so in the left part of the graph we are seeing?

Thanks I appreciate your input and thoughts..

OS on laptop, Manjaro Linux with Wine installed....Linux version of REW 5.31.3 installed
install
DATS_V3_setup.exe installed with wine installer. (right click install with Wine windows program Loader)
Installation path: home/.wine/drive_c/Program Files/
Open console and type winecfg hit ENTER
In Wine configuration window that pops up click Add application. Go to c/Program Files/DATSV3/ and select en add DATS.exe
In Wine configuration window select the just added DATS.exe and click audio at top window
I chose windows version 7 but other OS may work.

For the input and output device now there’s the just installed PCM2900C Audio CODEC Analog stereo option to choose. The rest i left at “System default” cause other settings also didn’t add any specific in and outputs. In other words I CAN NOT CHOOSE “SPEAKER” OR “LINE IN” like olen could in the manual DATSv3 on a MAC.

Also in “PulseAudio Volume Control” I chose PCM2900C Audio CODEC profile: analog stereo Duplex

When in REW ...for input and output device same CODEC is chosen...in and output were left to default
No option to CHOOSE “SPEAKER” OR “LINE IN” I think I have might have to edit some settings in Manjaro or ad pipewire or jack to route audio ins and outs...If you guys think the measurement is ok I leave it as it is for now.
have a good weekend

Marantz 300DC. I have one of these amplifiers and inside the amplifier is a small power transformer mounted in the front. The supplies voltage to these really small power supplies, one power supply for each channel mounted up towards the front.




These little power supplies provide a +/- 70vdc to the biasing circuit of each channel. I would imagine the current draw is pretty low. I made some corrections that were made by somebody that worked on it (no idea who did the work) and on power up noticed that the small transformer got pretty warm. Warm enough that the primary winding is now open.



I’m on the search for a transformer, but before I install a new transformer, I want to see what is going on. I intended to hook up a power supply to the amplifier channel so that I can see how much current is being drawn and make sure I get the circuit working otherwise. That way when I put the new transformer in, it’s good to go. It would be nice to see how much current is being drawn so that I might size the new transformer.



This is the amplifier circuit. You can see the +70 V goes towards the top feeding R723, R724, etc. The -70 V is towards the bottom feeding the collector of Q706, R729, etc.

I got it all hooked up as I was wanting to, and powered up the amplifier on a dim bulb tester. The bulbs stayed bright and I heard a “whirring” noise coming from the inside of the power supply. I immediately turned the power off and checked over things and nothing looked damaged at all. I was curious what the behavior was about. I found that the power supply outputs are shorted when they are turned off. I am seeing about 16 ohms across the outputs. Once I turn the power supply channel on the short goes away it course.


I am guessing this is the source of my problem. I thought I would come here for advice before going at it again. I’d really like to not damage this power supply nor the amplifie lol.

The next go, having everything hooked up I’m guessing I should have the +/-70 V turned on before powering up the amplifier? Obviously, they normally turn on at the same time when you’re using the original transformer inside of the amp.

Another thought I had was maybe wiring a diode in series, maybe a 1N4004 or 1N5404. Something to eliminate the short that the amplifier sees. I checked for backfeeding voltage at the points, where the power supply would hook up, but there was no voltage coming from the amplifier itself, which leads me to believe it was just the short it was seeing.

Would love some encouraging advice.

Thank you,
Dan

I'm working on a Lab Gruppen FP3400 with shorted outputs in one channel. My list of collateral damage includes Q1, which the service manual lists as an IXFN73N30 N-Channel enhancement mode Mosfet, but the actual fet installed is the APT30M40JVR. Regardless, neither of these are readily available from my usual sources, so I'm looking for sub suggestions. IXFN102N30P perhaps? 🤔

Hello friends
and @iancanada
I recently finished my first raspberry audio player with Sw Volumio.
Rpi4 4GB RAM
IAN CANADA UCPI Universal Ultracapacitor Power Supply Board for Raspberry Pi
Power supply: Toroidal transformer 2x 9V 5A
Power supply so far by one branch from IAN Canada 5V
Display: 7.9inch Capacitive Touch Screen LCD, 400×1280

Today a new sound card arrived:
IAN CANADA TRANSPORTPI DIGI II Ultra Low Jitter Digital Audio Interface Module.
https://www.audiophonics.fr/en/dac-and-interface-modules/ian-canada-transportpi-digi-ii-p-19555.html

I bought this sub for cheap and I'd like to make better enclosure for it. But I can't figure out what model this is (tried reverse image search and one reddit post but no conclusion) and I have no way of measuring the t/s parameters now. So can someone identify this or tell me how can one measure the t/s parameters for cheap.
Or the not best option, could someone say what could be good ported box for this based on the sealed that it came with?

Thanks

I'm going to design and 3d print 3-way speakers to install on the sides of a TV.
Either active or passive crossovers. I have the tools to measure and make both.

The TV is 90degree wall mounted at the end of an alcove, which is about 2m wide and I'll sit on a bed, close to a wall, about 2m from the TV/speakers.
The height between the bed and ceiling is about 1.5m.

I currently have some spare SB19ST tweeters, a pair of Omnes SW 5.01 woofers and for midranges I have:
2x Tang Band W2-2243S
4x Peerless TC9FD00
4x Peerless TC6FC02
4x Peerless TC6FD00
to choose from.

I'm currently thinking of designing a waveguide for the sb19st and maybe for the mids.
Then I'm leaning towards an MTM with the TC6FC02.
And I've already designed and simulated the base for a T-line for the SW 5.01:


The reason I'm thinking of 3-way is because the SW5.01 is a pretty heavy midbass with a lot of xmax, so I don't know if it could cross over well with the tweeter.

Now my biggest concern is with the waveguide/horn for the tweeter and the placement of the midranges, to get the best sound in the small alcove.

I know it's not going to be perfect in any way, but I'm thinking I should try and make the speakers have a narrower directivity, to not get as many reflections.

I know MTM makes the vertical dispersion narrower, but I'd also want to make the horizontal dispersion narrower.
Should I just place 4x mids in a cross pattern?

Or should I make a unity horn with the mids?
Like the UICW: https://www.diyaudio.com/community/threads/unitized-image-control-waveguide.319698/
I'd use this one, but it's just a little large and I don't see anyone measuring both the vertical and horizontal dispersions, and I think it plays too wide.


Or should I just give up and live with the reflections?

I have a 32x32cm 3D printer so the design possibilities are pretty limitless.

SOLD

Hi all
Selling some very good speakers for a project Troels developed -the SEAS Classic MKII
2 SEAS Prestige CA22RNY H1471-08 midrange - used, as good as new SOLD
2 SEAS Prestige MCA12RC H1304 woofers - new SOLD
2 SEAS Prestige 27TFFC H0881-06 tweeters - used, with brand new membrane voice coil units includ new front panels SOLD
Current retail price around 770 euros
Asking for 380 Euro plus shipping
Info: http://www.troelsgravesen.dk/SEAS-3-Way-Classic-mkII.htm

Greetings Friends. I have a DIT Class D amp I build according to this guide from IEEE Spectrum a few years back and it's been sitting on a shelf since I got into tubes. The amp has a 2x70w module from 3eAudio and their 2-in-4-out DSP based on ADAU1701.



Awww. my first amp.

Anywho, Now I build fancy tube amps and this poor guy is neglected. Alone. But smart and strong. I'd like to make him part of a hybrid Tube-Class D system. I have a little EL84 SE amp with glorious highs and poor bass. I'd like this amp to provide the bottom end.

I would like to program the DSP to be a 2-way Active Crossover, to send the lows to the Class D module and send the highs to a pair of output jacks for a 2nd amplifier. I have a pair of speakers with Bi-Amp capability, want to hear the magic.

I want to add a master volume control to the front end. I plan to add a 100k Log pot to the front panel and run the input directly to that, then to the DSP. Outs 1&2 will go to the onboard amp, Outs 3&4 will go to a pair of RCA jacks on the back panel.

There are 3 pots on the DSP. Crossover Frequency, Onboard Amp Volume, Bass Boost?

There are many projects out there for the Sigma Studio, is there one suitable for this? I suppose I could just watch the video where the guy builds a 2way from scratch...

thanks for taking a look!

w

I just grabbed a couple of Dahlquist DQ 10s for 200 Canadian is there a thread on this forum that can assist me with the subject of rebuilding them and potentially modifying the crossovers and possibly adding a passive rad to the back of the base cabinet I just registered on this site today so I’m not familiar with it my apologies for posting my question in the wrong section if I have done so

I got a new SCHALMEI feedback:
The schalmeis can't keep up with the horn of a Klipsch, but that's not so bad.
These are satellites and they need support down below.
Previously only for cinema use, the 18 inch corner horn has now been integrated.
The speakers are now connected to my Cayin tube amplifier and are separated with a second-order crossover from 80 Hz. The corner horn is connected to the tube via a high-level input (Reckhorn A409). At first the Fostex 206 were installed but these were replaced by TANG BAND W8-1772 and now I am very satisfied with my satellite system.
I didn't know this dynamic before and the details were overwhelming at first, but now this system is the measure of all things for me.
I've recently had a pair of active Dynaudios (16800DM) with me and they can only do a little more in the treble, so kudos to your design.

For about the last 10 years I’ve been using the same Rigol DS1102E. It’s alright, a decent two channel 100 MHz scope that gets the job done. About 4-5 years ago I got an old Tek 7603 with a couple 7A18 inserts and 7B53A trigger so that I would have an analog scope, but definitely use the digital for most everything.

I guess I’ve just become bored with the Rigol and was wanting to get something new, something with a bigger screen maybe. I’ve had my eye on a couple of the new Rigol 12 bit models, wanting to stick with 100 MHz or higher and wanting to go to four channels the options I was looking at were in the 700ish to 1000 range. Like the DHO924s. The DHO814 can be had for just under 500, has 100 MHz bandwidth and 4 channel, but not sure what is being given up at that price point.

Well, this past weekend was a local electronics get together/ swap meet. It happens twice a year here. I’m a vendor there so I get to go a day early to setup if I wish and also two hours early the day of to get first dibs on what I like before the public is let in. A good friend of mine also has a table there so he came early and knew I was looking to get a new scope. He has a buddy that also has a table there and only sells Tektronix equipment. He was a Tek engineer and service member (Tektronix was started in Oregon about an hour from where I live) and though retired is the go to for any Tek repair in the area. Anyways my friend saw a scope he was selling and I took a look at it. He offered it to me for a substantial discount on what he had it priced and if I was going to buy it I wanted to do it before the general public was let in. There were hundreds of people in line to come in. So I grabbed it.

It’s a Tek TDS 684A, 1 GHz, 5GS/s 4 channel scope. I paid 250 for it, it functions perfectly and is in fantastic shape, screen is nice and bright and the front panel is pretty much perfect.

Is it an upgrade from my old Rigol? absolutely. It feels to be much better quality. I saw the original price of this scope and was shocked. Cost as much as most cars. Will I ever use the 1 GHz bandwidth, probably not, but I don’t know.

So thoughts? I’m sure I could easily get my 250 back out of this scope. I see there are broken examples that sell for more. It’s approaching 25-30 years of age, somewhere in there. It has a smaller screen then the new Rigols, but I also got it for 1/3 the cost and in some ways it specs better. Should I keep the money I saved and put
It towards a new analyzer or power supply and keep this new (to me) Tektronix scope or sell the scope and spend the extra money needed for a new 12 bit Rigol?

Would love opinions
Thank you,
Dan

Hello everyone,

My project is coming to maturity but before ordering everything I would like your opinion on my project.

Components :

HP + AMP :

• Subwoofer 4 Ohm : Tang Band W5-1138SMF
• 2x Full Range 4 Ohm (Re 3 Ohm): Dayton Audio RS100-4
• Amplifier: AIYIMA Bluetooth amplifier TPA3116, 2.1 audio card, 2x50W for satellites, 1x100W for subwoofer. Link: https://a.aliexpress.com/_EQYXqNI
• All connected by 2.5mm speaker cables

POWER SUPPLY :

• Dayton Audio LBB-5v2 (5S with 5 26650 3.7V 5000mAh units), which will supply the amp with 21V in principle
• charging via a USB C port that I'll plug into the back of the box

DIMENSIONS :

• 18mm MDF wood
• for the two satellites, each will be insulated in a sealed enclosure, dimensions based on parts express recommendations.
• for the Woofer 6,6L with a Bass reflex of 2,5cm on approximately 14cm.

CROSSOVER :
No crossover, the subwoofer output on the amp cuts at 250Hz, and I'm using the full spectrum on the Full Range satellites, not particularly ideal but the sound should be pretty decent according to my simulations. There will still be a bit of dispersion at the top end of the spectrum, but a tweeter isn't in my budget!

I take all opinions and answer questions, so don't hesitate to ask!
One of my doubts concerns the impedance of the 4Ohm satellites (Re 3Ohm). Wouldn't I be better off with 8 Ohm?
And if you have any idea of the autonomy I can get with this battery pack, that would be great!

Thanks a lot!

I ONLY have my old DS-215-8 woofer , can't afford much more.
I am using a dome tweeter crossed over at 2K presently.

What I am curious about is the implementation of the (4th order LPF ??) and the 10R/22uf/2mH (notch filter).
The tweeter Xover is straight forward and works out in the calculators , but the 4th order is a mystery ??

MTG designs - https://www.mtg-designs.com/diy-speaker-plans/flex-8 -
has the PCB and schema to use this old woofer in what looks like a valid HQ design.
I am about to collect all the various iron core inductors and NPO caps for the woofer side of the Xover.

Is this strange implementation the "secret sauce' to tame the 1K-3K response of the LF driver ?
None of it works out in any online calculator but the result looks nice (below 2).
I might have better 15-20K with my properly padded dome tweeter , but I'm a little bit in awe of
this xover's complexity - would love to know how it works besides just being to identify the sections ??

PS - I'm running it now with just a 2K 2nd order on the woofer - sounds a bit bright in the vocal range.
REAL loud SPL 110+ , still a bit bright mids (but real clear) .....

I was running old (mission domes) at 1.2K - blew one of the tweeters !!

OS

Hi folks.

Has anyone used one of the below sockets?

I'd like to try mains filtering but I'm absolutely not spending a small fortune.

IEC mains filter doo dah

Simple question... I'm going to use a fused mains inlet from Schaffner and I just assumed the version with filter was the smart choice to reduce noise conducted into the amp.

It has since been suggested that it would be unwise to filter the mains.

What say you, learned folk? Filter or no filter?

Pops

Hello,
I was looking at some commercial IEC filters with an intention to clone them. My understanding is that even if the schematics are available, the lay out and actuall construction might be critical for performance so this would be a good reason to buy the ready products. But my little research left me with more questions about how to choose them. In particular, among the models for different current consumption, the only thing that change is the inductor's value: as the current goes up inductance goes down. I suppose it has to do with inductor's saturation but anyway how do we choose the proper filter for a given device? If, for example, the current consumption is at 1A then filters rated at 3A and 10A would perform differently?

I also found datasheets stating inductance at a certain frequency. What would that mean? Does inductance change with frequency?

I read somewhere that a hump around 600 hz will sound boxy and that more stuffing can help with that or a rise around 3000 may sound strident and needs a resistor what are some other freqency response deviations and the effect and solution. Just curious and I spent quite a bit of time looking for this information and really cannot find much. I have a average 5 db dip between 100 and 200 at the listening position not sure what this causes or how to fix it.

Hello

can you advise me i want to have a sub to follow my chp 90 and chp 50 ideally it could be better if it's the same what can you advise me?

Hello, I need some advice regarding an old battleship Sony CD player I recently purchased. At some point in its life, it had a Trichord clock upgrade but this has been removed. I'd like to return it to stock but it's missing the original crystal oscillator. I know the frequency I need (16.9244M), but I don't know if essentially any crystal will do the job? A quick web search throws up a ton of results for oscillators, are they pretty much all the same?
I'll have to replace the components around the original crystal as they've just been snipped and left in place, other option is to try to get another external clock and pick up a DC supply from somewhere in the player.
Any advice would be greatly appreciated!

For sale a pair of ACA MJ Racam built these on a wim and have collected dust since first test, please see photos.

R1/R2 on one board arnt raised above the board so could probably do with replacement and the washers holding down the fets could do with being replaced but everything else is good.

I would recommend setting up again before use.

UK mainland only

£90 ono This will include Postage to mainland UK

Hello,

It is a high voltage switcher NPN in TO-220 package, 400V 12A. I have the "L" suffix ST13009L, can't find any model online. It is an old-ish part but still listed as active on Digikey, however no spice model for it on ST's site... weird. Still looking but if you guys have one in your archives that would make my day! I'm using LTspice.

Regards.

Please post ideas of how you make crossovers with different kinds of adjustements. The easiest way is off coarse to use a variable L-pad for the tweeter, but it is a lot more options as i understand:







https://davis-acoustics.com/en/mv-one-master-2/

Hey everyone.

Iam a big fan of the old transistor based consoles especially Neve 80 series consoles and the sound of them, I have nerded out on designing my own modules and now I want to take it a little further and use some of my old 1:12 transformers, to make a mic preamp. but with a transistor amp.


Iam looking for transistor based schematics for mic preamp that can use a 1:12 winding input transformer. If it has ever been made.
I know a 1:12 ratio winding would be made for tube amps. But I wonder if anyone back in the days 60’S/70’S made any mic pres in consoles for that type of transformer, that was transistor based.
Or also someone nowadays who made it would be of interest.


Let me hear if you heard about such thing or what your thoughts are on the idea.
Thanks
Kind regards Bob

Hello, I am about to graduate from grad school and will finally have some money! So I am getting back into hifi audio. Car and home music listening.

can anyone identify this tube amp , i want to restore it and i need a schematic , i think it was used in some type of tone cabinet , there is no markings on it other then 2222 printed on the front of it . power tubes are supposed to be 6l6gc , other tubes are 6c8 , 6c5 , 6h6 , 5u4 rectifier ,
the power transformer is branded STANDARD RADIO PRODUCTS OF KITCHENER ONTARIO CANADA .
Please let me know if you know what it is.

I have found that low Intermodulation Distortion is a good indicator of sound quality. The last couple of years I have been measuring 10-12" subwoofers and 6-7" midwoofers in IMD, I will now share some testing in 8" drivers.

The test enclosure is a .5 cu ft (14 liter) sealed box with the bottom lip of the speaker just 2 inches above the floor. The microphone is on a stand 49"high with the base of the microphone 33" from the driver. A distance of about 1.5m from the speaker to the microphone. As I'm not measuring in an anechoic chamber my measurements are not comparable to anyone else's but comparisons can be made between the drivers I test.

Feel free to make suggestions on what drivers you want to see tested.

Hi i have one Behringer a500 unused on which i would like to replace all the electrolytics with better parts The stock ones are scaring
The nice things of this unit are balanced inputs and a decently sized toroid (i know nothing about its actual quality)
i am attaching the schematic
I read of some distortion issues for different position of the input attenuators
Looking at the part of the circuit



i see a strange R71 and surprisingly a pot value bigger than the input impedance at the opamp
I always thought that the pot value should be lower of the following stage input impedance
Can i eliminate R71 at least ? i dont like it at all
Thanks a lot

Feedforward Error Canceling, in theory, could cancel most of the distortion. You could get 0.002% THD figure without much efforts with this technique, at least in simulation. A good example is the famous Current Dumping. If you don't know how Current Dumping works, I highly recommend you jump to this thread to learn how it works and what it can achieve. Current Dumping with OPAMP

Besides Current Dumping, the same technique, Feedforward Error Canceling, can also be implemented to other topology. Here I use a Blameless style amp for example.

See the example below, the Blameless style with EF2, with an average loop gain. Pretty common setup. Please ignore C1 and R7 for now. They will be used later. The idle bias is at 136ma. 10KHz 20Vp into 8 Ohm is about -72 dB THD.


To implement Feedforward Error Canceling, you need pull a resistor from Miller cap VAS side to the inductor speaker side. However, the VAS doesn't have the capability to drive the feedforward resistor directly. The work around is to create TMC (Transitional Miller Compensation) around the driver stage, and use driver stage to drive the feedforward resistor. See updated circuit below. R13, R4, C1 create a transitional network for the Miller compensation.
From the simulation, you can see all the distortion is gone!!.

The optimal value of R7 depends on the inductor value and also the loop gain bandwidth of the amp. The loop gain bandwidth of the example below is about 600KHz. Thus, the optimal value of R7 should be 2 * pi * Bandwidth * L = 2 * 3.14 * 600,000 * 4.7e-6 = 18 Ohm. If you still don't know what is going on, please search Current Dumpling and learn it. This technique is highly effective but also overlooked.



[EDIT]
PS: In the example above, there are 2 things going on. One is TMC, the other is the feedforward error canceling. They both contribute to lower the THD. The TMC may cause other stability issue. I recommend to check the final version that is without the TMC.

I’m playing around with a suspension for my new plinth and did some rough measurements of the two options that others might find interesting. In the plots below Z is up and down X& Y are horizontal. “springs” are a set of metal springs from a VPI HW19 “With Damping” means with the original VPI foam inserts in the springs. “Foam” is mixed cell polyurethane designed for building or machine foundation isolation. “Constrained” means that I built a solid wrap in the XY dimensions from plywood about 80% of the height of the foam blocks. I calculated the size of the foam blocks from the manufactures literature and should be getting a resonance close to what I get with the springs but I think the manufacturer’s data is based on wide thin sheets and the shape I am using (essentially a cube) is changing things a bit. One thing you can’t see in the roughly 1 second of data I posted for each is that the undamped springs rang for an incredibly long time, minutes in fact. The vpi foam inserts while they did raise resonance a bit cut the ringing time considerably.

I have two AMP2 modules. Both are missing main caps.

State unknown but output transistors are all good.

I have complete circuit diagrams.

€200 + shipping at cost.

R

Hi there,
I want to exchange the cheap coupling caps on the Cary SLP 90 clone board but the caps I have at hand are not rated 400v as the once on the board.
Do I really need the 400v rated caps at this position?



Thanks Klaus

Looking for circuit board mount 4 pin socket 300B. Seems nobody is selling them

Hi all, first post on this forum!

I am embarking on on a new project with a friend who is a skilled cabinet maker with access to cnc etc to build some speakers inspired by Fostex lab studio monitor series.
https://www.preservationsound.com/2013/09/fostex-laboratory-series-pro-audio-monitors-c-1980/

The plan is to use the plans for the h400 horn available here: Here is construction plans for Fostex Type of H400 wooden horns - Techtalk Speaker Building, Audio, Video Discussion Forum make out of Sapele and match with a modern 1 inch comp that is suitable (any suggestions welcomed - thinking BMS 4550 or B&C 250)

and build a LF box inspired by this matching cab from the 80s:

https://www.fostexinternational.com/docs/speaker_components/pdf/recom_enclose/w300aII_encl.pdf

but modify for B&C 12NDL76 rather than the original Fostex driver, which I have done here = Subwoofer Box B&C Speakers 12NDL76 | Ported Box | Slot .

Planning to run as low as possible and cross at 800hz as per the original design - to the horn then run a super tweeter from 7k up, (Fostex FT17H?). Does my design look suitable for this?

Not confident in crossover design but have used lots of DSP in live sound scenarios, but would rather run passive from one amp rather than active with DSP on 3 amps so need to work that out. The original crossover plans for the H400/Wa3002 combo are available, how much would it cost to get give someone a list of the drivers I am using and the old crossover plans and get them to make a passive crossover? Thinking Crown macro tech amp(s).

Thanks in advance!

Hey,

Which are your favorite dual (matched) JFETs for differential pairs, that you miss the most?

I was thinking, for example, 2SK389. What else?

Thanks!

Most components are new or used for tests. See photos for details:


Jantzen Air core coils:

1.2mH, 1.6mm, 0.27 ohm, 30x60 mm, 550g, SOLD


NEW: Nihicon KW 2200uF 63V capacitors, new, bought from Mouser, 15 EUR/set of 8 x1


Send PM for details. Price is per piece + post costs, Payment via Paypal.

Hi, I'm Henk from the Netherlands. A long time ago, I was probably 12 years old, I started building amplifiers. I used the DIY kits from Philips for that, I built preamplifiers, a complete 8-channel mixing console and power amplifiers. In that period I also started building speakers.
When I was 18, all that building was a bit over, I was too busy with my studies and work. I was already working in security at the time and built the central units myself for various large projects.
Now a few years ago, before my retirement, I started building speakers again, for example the Klipsch Cornwall (Klonwall). About 2 years ago I started building Horn speakers from Western Electric complete with separate crossovers. These are now finished and I am very happy with the sound that comes out of them. I also bought a tube amplifier (so not built) during that period, the Willsenton R8 and I was very happy with it until I saw a video from Stephe (Skunkie Design) about modifying this amplifier. I did most of the modifications then. A few days ago I had some problems with the amplifier and then I sent Stephe a message which she promptly answered and of course was able to solve my problem, through Stephe I also came into contact with DiyAudio. I hope I can learn more about building audio equipment here.

Hi all,
I've been searching around without any joy for evidence of noise measurements of modern batteries or supercapacitors when used as power supplies for digital circuits.
I can see older references and measurements for lead acid and nicad batteries in various articles and in threads like this Battery-powered supplies - diyAudio
But I can't see anything similar for supercapacitors or for example LiFePo4 batteries.
I've heard very good reports from people using lifepo4 with a float charger to power their dacs, but I'd like to understand some of the theory and benefits.
Is anyone aware of any publicly available results comparing lifepo4 to other methods of low noise power supply?
Thanks,
James

Welcome new member,

Start a thread here and introduce yourself to activate your forum posting privileges. Please save your technical questions for another post. The Moderation Team will approve your introduction, if you would kindly allow us a little time for this to happen we would appreciate it.

Please note, we are an English speaking forum. Posting in the forum's legitimate sales area is restricted until new members have built up a small count of quality posts elsewhere on the forum. This is done for the protection of both new and established members.

We're looking forward to learning about your journey and how we can help you.


diyAudio
Moderation Team

* Threads other than introductions created here, and other non-complying posts may be removed or other such action at the discretion of moderation.

I am looking for a schematic for a 1935-36 Gibson EH150 1st Generation second series amp. I've been asked to bring it back to stock but it came with a 5U4 rectifier, 5V6 and 6V6 power tubes, and a 6A6 preamp tube. I know the 5V6 and 6V6 can't be right and the 5U4 rectifier is a question mark. It looks like the amp was recapped in the 60's and the tech who did it splattered solder all over and did a really bad job. Does anyone know where I could find a schematic? This is a very early amp with no volume control or any pots at all. There is a resistor on the one input jack and a cathode resistor but that is all. There is a choke, a field coil speaker, and a lot of dust. Any help on a schematic would be fantastic!

I bought these cheap off ebay. Seller said 10K ohm-4,8 Single End Transformer. Quite Large and heavy. I would guess Chinese.
Just thought someone here might recognise these. 200 for the pair so the impulse kicked in LOL. He mentions Yaqin but I'm not sure
about that. Thanks

I am still not finished building my monster OB line array speakers but am already looking ahead for a next build



My next build will run also use a ESS Heil tweeter >3khz
The mids will be two alpair 12p's

For the woofers I am eying the 21" Lii Song OB drivers. Problem is there are 2 versions from 2 different Lii Songs.....

Version A



Version B



Version A has higher QTS and QMS and dual voice coil.

Version B has vented pole piece, higher VAS and thicker plates and looks a little more premium to me, even though it is slightly cheaper.

Which one would you pick and why?

I purchased six Tang Band W5-876SE 16 ohm woofers on closeout from Parts Express several years ago and never got around to doing anything with them. I'm thinking about using them for MTM speakers. I've searched around quite a bit and have found many posts that mention that they can be used for MTM but no specific info on how to best go about it. Where should they be crossed and what type of tweeter would be work with them? Are there any existing designs? I'd also consider some kind of TL enclosure if that would sound substantially better. They'll mostly be used for music.

I'm trying to find a (2SK433) SMD transistor with the marking (KE) or a replacement.

Would this be a good combo for a small subwoofer.

Peerless 830452 10 inch sub and this

10" passive radiator for Sonus Faber speaker.

https://www.jktukku.fi/product/4177/tymphany-10-bassoelementti

Guessing this is the driver used in older Gravis B1, the Gravis B1, has two passive radiators, Sadly I only have access to 1 passive radiator

Hi

The reason why I joined this page is to get some help with audio issues. I know a little about audio technics so I really couldn't solve my problems. But this new world of sounds is really interesting so thought I might join.

Adam
Odorheiu-secuiesc

Hi there,

I registered here, because it seems the only place where people are discussing multiuple things from my current setup.
I want to give and get some feedback about minor modifications that I have planned.

the speakers: https://www.diyaudio.com/community/threads/panasonic-sb-pm28-active-crossover-help.301156/
and the crossover: https://www.diyaudio.com/community/...uit-diagram-for-a-weah-d222-crossover.406079/
for this setup I use a SMSL AD18 Amp.

Best regards

Hi all,

New member here, moving over from the DIY live sound/Soundsystem world and have some questions for a smaller scale project!

So I was one of the lucky ones to be able to build and own one of a few hundred 2021 DIY Sony VFET amplifiers as pre built (OS) and tested by mr. Pass.
Now, due to significant downsizing, basically losing a hobby/listening room due to family expansion, I put this amplifier up for sale.









The amplifier is the N-channel version, see link to build thread. I have built it fully as stock and the Meanwell SMPS is included. In the past two years I have had the amp playing compression drivers on Yuichi Horns from 600hz and up. The sound, well this forum will back up it's qualities 🙂


Please send me your best offer + shipping and paypal fees from The Netherlands. I'd rather have this amp making someone happy than it being not in use at my place but if it does not meet my price, I will keep it as the collectors item it is. 🙂

On another thread I proposed several sophisticated RIAA preamps, adding LTSpice simulations for all or most of them.

One of the main problems in simulating RIAA preamps in any program is that you have to add a load that includes both the anti-RIAA and the cartridge.

The one I found the most interesting one was an opamp representation of an idea Erno Borbely had proposed years ago in The Audio Amateur magazine, in a discrete preamp design e introduced there.

The RIAA part of the preamp was split in two preamps: the first one being passive and the second being active.

So with the help of some DIYAudio friends, which I hope show themselves here, it was arrived to working preamps with excellent simulation specs.

To start showing models and sims, I will start by what I consider a brilliant development by Hans Polak to the original proposal by EB.

It is to be noted that also MarcelvrdG contributed to this design.

I've seen a lot of kit on many forums, but often it comes with a lot of visible cables.

This may be quite acceptable to those contributors, but it's quite easy to hide most of them if you choose.

I'm a tidy person, so I don't like to see them. They can also be a trip hazard, more of a problem, if something expensive then gets dragged off a stand when it happens.


I use plastic trunking. it's dirt cheap, easy and quick to fix, either with a few small screws or just the adhesive that is on the back.
Mine sits on top the skirting boards and is hardly noticeable. Of course, any change of equipment can be accommodated as the tops just clip on and is easily removed and replaced.



Now I know this won't interest many, but perhaps it will some.

Cables from one double socket feed the TV and everything under it to the left and the wall unit lighting and all my audio equipment to the right.







This feeds my electric piano, its amplifier and the music stand lamp.






There are two pairs of cables to each of these jukebox wall boxes, which have quick release connectors behind them. The cables pass down inside the trunking below the shelf, then along more trunking on top of the skirting board, then disappear behind the wall unit.



This trunking comes in different widths and lengths, here in the UK, usually in 3mtr lengths for just a few pounds. Easily cut with a small saw. You can get "elbows" for them but they aren't really necessary.

Hi, all!

Just joining. Starting with saying thank you to user DannerD3H for making a guide for Hypex HFD newbies. Really appreciated!

Have just started building a pair of active speakers using FA253 and having no prior experience of any design or build.

Anyone wants to coach me through this project?

Denis
London

G'day Guys,

I've been playing around with Mark Johnson's UDP3 in LTspice.

Firstly to understand what its doing and secondly to modify it to my purpose.

I don't understand the 2nd stage clamped capacitance multiplier entirely and I can't find a model for the AZ431AZ so that I can simulate it.
From what I can figure out the purpose of this subcircuit is to set the output voltage at 19v (aside from the reduction in ripple).

I would like to be able to use the UDP3 for input voltages other than the specified 22vac and output voltages other than 19vdc.
With this goal in mind it seems like the clamped capacitance multiplier subcircuit should be modified or dropped to allow the extra flexibilty.

I've whipped up a sim in LTspice however I am very new to simulation so please forgive me if things are not done well.

I have omited everything up to and including the rectifiers as unimportant for the work at hand.
I have also omited the ferrite beads as I can't figure out how to sim them properly. I don't think these are very important for the sim anyway.
I couldn't get a model for the TIP122 to work so I am using the model for the TIP142 as close enough for my purpose.
So starting with the first capmx stage, here's what I have come up with.

For 25vdc in, I am getting 3v drop which seems reasonable.
With a 0.35Vrms input ripple. I am getting 3.4mVrms out.
40db reduction in ripple according to my calculation.


Adding a 2nd stage the same as the first drops another 3v and gives me ripple so low I can't see any in the sim even with the scale set to pV.

So a couple of questions to get the ball rolling.
1)Are my assumptions reasonable so far?
2) Is 350mVrms a reasonable ripple voltage for something like a 150mA load
3) Is there a way to figure out what the ripple is in the sim when it is so low the line is flat on a 1pv scale?

I would like to figure out what improvement in ripple reduction would be from adding a second stage.

My main use case for this circuit will be as a 'pre-regulator' before a VRDN style denoisered LM317/337 in place of a CRC filter.

So the ultimate question is:
If one was to simply chop off the clamped capacitance multiplier and put it in front of a denoiser, is there much benefit to adding a 2nd capmx stage?

Hi, I'm trying to repair the Nakamichi NHMD600.1. I don't have PWM on the output transistors. On the driver board, it seems that 2 components are missing. Does anyone know this driver board?

thanks

Hi there - I was kicking around the idea of making a Pure Audio Project (PAP) clone using an 8" full range with 2 15" woofers...but the x-over had me ruffled. I've never built a speaker or cross over and wasn't sure I wanted to tackle it. Plus I'm not completely convinced a FR will give me the top end I want so I was thinking of adding a tweeter/super tweeter of some kind. I was also thinking about trying to add Dirac room correction to my system. Then recently I've been reading about how far class D amps have come, and maybe thinking of trying something in that vein. Enter miniDSP's new FlexHTX; eight channel dsp with Dirac built in--talk about flexibility. So, and bear with me here....consider an active three way PAP clone using the FlexHTX as the cross over. Drivers would be two Bianco 15" drivers, a Tang Band W8 full range driver in the middle, and some sort of AMT or Ribbon tweeter mounted next to the full range, NEO 3 for example or Mundorf ($$). Amplification would come from two three channel Purifi based class D amps like Buckeye or one of the other similar ones out there. I'd run the woofers up to 400hz, the tang band from 400-8k or so and the tweeter from 8k up. With the functionality of the Flex I can do all the x-over work digitally, time alignment etc and room correction. I'd still have two channels in the x-over left over for subs if needed. I'm confident I can build the open baffle.

What do you all think of this idea? I don't love being bound to using the miniDSP's DACs...but to be honest DACs are all getting pretty damn good and the idea of getting the cross over "right" plus the in-room correction probably makes up for whatever shortcomings the onboard DACs might have.

What am I looking for? Big, open sound, excellent imagine, dynamics, clarity. Music is a wide range but mostly country rock (Grateful Dead, Bill Strings) and 80s rock and small group be-bop jazz. Really looking for that big immersive soundstage I hear people describe from open baffles without giving up the dynamic impact of high sensitivity speakers.

I'd have to liquidate most of the existing rig to fund something like this, and I don't love putting pre/dac/x-over all in one box but maybe that's the ludite in me. I keep reading/hearing great things about the clarity and transparency of these class D amps and seriously considering taking the plunge in this direction. Tell me what you think!

The list of differences between LDR Pre MkII and original VxD LDR volume controller is so long that I thought it might require a new thread, even though LDR Pre MkII is actually a spin-off of amazing VxD from Vincent:

Arduino based LDR volume and source selection controller

1) Instead of Arduino Nano which runs on Atmega328P, LDR Pre is driven by Atmega328PB which can be found on some Chinese Arduino Nano clones. To utilise however the full power of "PB" which has three native 16 bit timers instead of one, Nano clone boards require hardware modification to expose additional pins on "PB", as well as new bootloader which uses serial1 instead of serial0.
2) LDR Pre has native 16-bit "DAC" capability, instead of 8-bit DAC in VxD. This allows smooth volume changes without impedance range switching which was causing volume bumps due to time constants in RC filters at PWM outputs.
3) LDR Pre supports only OLED with SSD1306/SSD1311, no LCDs any more. OLEDs from Aliexpress running on SSD1309 are not supported - I was not able to make them work over I2C.
4) LDR Pre has firmware which stores all the parameters in EEPROM.
5) LDR Pre fw has ability to change all the parameters from user interface, including: load and nominal impedance, screen brightness, screen saver timeout, welcome message, I/O names and LDR min values, max saved volume level, measured 5V voltage, etc.
6) Entire user interface is accessible by a remote or encoder. You can use only one of them or both to access all functions.
7) Backlight pin is now used to control power amp relay
8) Entire board runs on 5V. Built in Nano 5v regulator is not used any more, so less heat on the controller board. OLED now draws current from power supply directly instead from Nano.
9) Power supply is now delivering 4X5V instead of 2X12+8V.
10) There is no feedback code to maintain constant current in LDRs. I found this routine to cause more instability in impedance than environment temp, so I removed it. This allowed more room for additional functions.
11) Since all the parameters are stored in the EEPROM, it's possible to deliver unified, one-size-fits-all precompiled firmware updates without involving Arduino IDE and all the hassles it carries. There is no need to have IDE installed at all to update firmware or change parameters.
12) Calibration routine has been changed and optimized to accommodate 16-bit timers.
13) There is an option in the menu to reset all parameters and names to default values.
14) Firmware is power amp friendly - it can be configured not to save volumes above max value stored in EEPROM. By default this value is 10 (out of 50).
15) Firmware boots into standby mode. Pressing play button on remote for 3 seconds turns on the device and powers up the power amp (if connected). Pressing it again for three seconds puts the device in standby mode again and turns off the power amp stage.
16) Pressing center button on (Apple) remote or encoder for 3 seconds enters the setup menu.
17) There is now a child lock in the firmware, which allows to disable encoder and operate with remote only.

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I find myself in possession of most of the parts for a 2016 SONY VFET amplifier.

I picked up PCBs here that were populated originally for use with K60/J18 devices…of which I have a few.

However, in searching for a pair of the special mounting brackets used with this amp project I also acquired a pair of J28 KF33 VFETs here in the swap meet.

They were originally from
CircuitDIY Acronman according to the seller.

Not curve traced. No Vgs written on them. I’d have to figure out the testing procedure to determine Vgs.

Still, I’d like the opportunity to assemble the amp as NP originally designed it.

To my knowledge NP never curve traced the VFETs. My understanding is he measured the Vgs of the devices and then I suppose he tried to put together pairs of the K82/J28 that would avoid any serious operational problems in the circuit.

I’m looking for a pair of K82 that would work with the J28 KF33 I have properly in the circuit.

I’d be willing to buy them outright or would consider other options such as trading for some of the K60/J18 devices I have which are perfect for the SONY VFET Part 3 OS project.

I would also consider buying K82/J28 pairs if there is someone who has them from a reputable source that never got to building with them.

Again, I don’t feel obligated to have curve traced matched pairs.

In the event that someone does have some special curve traced matched pairs of K82/J28 and they are interested in a trade then I might consider offering some Semisouth R100 curve traced matched pairs that I have hoarded in exchange.