Hodgepodge
Identical post on ASR ( https://www.audiosciencereview.com/forum/index.php?threads/hodgepodge.61979/ )
Quick story: Went to my storage unit and found some parts I never used for an old project I canned. A pair of KEF SP1632 drivers and a few dayton 5 1/2" Epique drivers. So I was playing around in CAD to see if I can make something relatively compact. I think I may have stumbled into a cardioid design. Here's what I got:
This would be an active design. I found this a little while ago ( https://www.tinyosshop.com/index.php?route=product/product&path=158_193&product_id=1233 ) which should allow me to even out the response between the KEF and the daytons. I would like to put something in the port chambers in order to create small group delay, enough to drag the signal 90 degrees out of phase, but I'm not sure what I could use. DSP would take care of the rest. I still have a lot of little details to work out, but that's the gist of the design. Would love to hear from the community on what I can do to make this work. If it won't work it won't break my heart, but I figure this could be a good learning experience either way🙂
Quick story: Went to my storage unit and found some parts I never used for an old project I canned. A pair of KEF SP1632 drivers and a few dayton 5 1/2" Epique drivers. So I was playing around in CAD to see if I can make something relatively compact. I think I may have stumbled into a cardioid design. Here's what I got:
This would be an active design. I found this a little while ago ( https://www.tinyosshop.com/index.php?route=product/product&path=158_193&product_id=1233 ) which should allow me to even out the response between the KEF and the daytons. I would like to put something in the port chambers in order to create small group delay, enough to drag the signal 90 degrees out of phase, but I'm not sure what I could use. DSP would take care of the rest. I still have a lot of little details to work out, but that's the gist of the design. Would love to hear from the community on what I can do to make this work. If it won't work it won't break my heart, but I figure this could be a good learning experience either way🙂
Cayn Vacuum Tube CD Player CDT-17A repair and new Project
- By sergiob
- Digital Source
- 7 Replies
These days I started restoring an old purchase, a Cayin CDT-17A CD player that I bought years ago for a modest price, $200. The CD player had various problems, someone had tampered with the PCB to the point that it no longer worked. I managed to "resurrect" the CD player, I asked myself the question, leave it like this or redo everything, and, how to proceed? In the absence of an electrical diagram and taking advantage of my passion for PCBs, I redesigned everything, separating the various stages, Control, Power Supply, DAC and finally the Tube power supply and audio and the digital audio outputs. The result is this. Now, is it possible to improve on the original design? Does anyone have any ideas?
On the net you can find something, but nothing of that!
ORIGINAL
NEW POJECT
On the net you can find something, but nothing of that!
ORIGINAL
NEW POJECT
The Nightmare Before Labor Day
- Multi-Way
- 202 Replies
The acoustics in my new home are horrendous and I have to figure out a way to deal with that, or else find a new hobby.
This is my old place, in San Diego. The main room is really wide and deep and the ceiling is a standard height.
Four years ago, I lived in a tiny condo, and one of my top requirements when I bought a house was a big living room. I had to sell my Gedlee Summas in 2016 because my old condo was way too small for such a big speaker.
The living room in my new place is about as large as the old place, but the ceiling is nearly 30' high. When I bought the place, I had daydreams of a space where there would basically be no 'ceiling bounce' and I thought this room would image like a dream.
Instead: it's an acoustical nightmare.
So many issues with his space:
1) Due to the fact that there's absolute nothing between the speakers and upstairs, you can play music in the living room and it's about as loud upstairs as it is downstairs.
2) Due to the fact that there's nothing between the kitchen and the living room, anything that's going on in the kitchen interferes with the living room. Last night we had guests over and I had to put my chair a meter away from the TV, just so I could watch a show.
3) Every surface in the house is flat and reflective. It's like putting speakers in a warehouse.
So I gotta come up with some way to tame this space, acoustically.
My initial idea was a CBT of Unity horns. The idea that I had, was that you could array a vertical series of Unity horns and get a beamwith that's 30 degrees or less. The idea was that I could listen to music or watch a movie without bugging everyone else in the house. After discussing this on the Facebook group, I came to the conclusion that an array probably isn't ideal. The problem with an array, is that it doesn't control directivity to a low frequency. For instance, an array that is one meter tall will control directivity to about 340hz. But nearly all of the issues that I'm having in this space are at low frequency and ultra low frequency.
For instance, on Monday I was trying to watch "Heat." In the movie, the action sequences are about 20dB louder than the dialog. This creates a catch-22:
* if I lower the volume to accomodate the action sequences, the dialog is completely unintelligible
* if I play the movie at a decent volume level, the action sequences irritate everyone in the house, particularly if people are sleeping. My wife's complained about this, and I've even had guests complain about it. (My guest room is on the opposite side of the house, about as far from the speakers as you can get.)
The obvious solution would be a dedicated home theater in the basement. Which would be great if I lived where homes have a basement. In Nevada, there's exactly one house with a basement, and it's built to withstand a nuclear bomb:
Las Vegas House With Doomsday Bunker for Sale
Although I'll admit that buying a fallout shelter and installing Unity horns in it would be a very Patrick Bateman thing to do, I don't particularly like their decorating choices.
So I have to come up with a plan for this space...
This is my old place, in San Diego. The main room is really wide and deep and the ceiling is a standard height.
Four years ago, I lived in a tiny condo, and one of my top requirements when I bought a house was a big living room. I had to sell my Gedlee Summas in 2016 because my old condo was way too small for such a big speaker.
The living room in my new place is about as large as the old place, but the ceiling is nearly 30' high. When I bought the place, I had daydreams of a space where there would basically be no 'ceiling bounce' and I thought this room would image like a dream.
Instead: it's an acoustical nightmare.
So many issues with his space:
1) Due to the fact that there's absolute nothing between the speakers and upstairs, you can play music in the living room and it's about as loud upstairs as it is downstairs.
2) Due to the fact that there's nothing between the kitchen and the living room, anything that's going on in the kitchen interferes with the living room. Last night we had guests over and I had to put my chair a meter away from the TV, just so I could watch a show.
3) Every surface in the house is flat and reflective. It's like putting speakers in a warehouse.
So I gotta come up with some way to tame this space, acoustically.
My initial idea was a CBT of Unity horns. The idea that I had, was that you could array a vertical series of Unity horns and get a beamwith that's 30 degrees or less. The idea was that I could listen to music or watch a movie without bugging everyone else in the house. After discussing this on the Facebook group, I came to the conclusion that an array probably isn't ideal. The problem with an array, is that it doesn't control directivity to a low frequency. For instance, an array that is one meter tall will control directivity to about 340hz. But nearly all of the issues that I'm having in this space are at low frequency and ultra low frequency.
For instance, on Monday I was trying to watch "Heat." In the movie, the action sequences are about 20dB louder than the dialog. This creates a catch-22:
* if I lower the volume to accomodate the action sequences, the dialog is completely unintelligible
* if I play the movie at a decent volume level, the action sequences irritate everyone in the house, particularly if people are sleeping. My wife's complained about this, and I've even had guests complain about it. (My guest room is on the opposite side of the house, about as far from the speakers as you can get.)
The obvious solution would be a dedicated home theater in the basement. Which would be great if I lived where homes have a basement. In Nevada, there's exactly one house with a basement, and it's built to withstand a nuclear bomb:
Las Vegas House With Doomsday Bunker for Sale
Although I'll admit that buying a fallout shelter and installing Unity horns in it would be a very Patrick Bateman thing to do, I don't particularly like their decorating choices.
So I have to come up with a plan for this space...
Oppo new UDP series players - 203/205 - Discussions, upgrades, modifications
- By Coris
- Digital Source
- 852 Replies
Attachments
HF driver diagram failure, defect or too much power
- By maxolini
- PA Systems
- 41 Replies
Guys,
Last Friday gig one of my tops just go dull, so I noticed and when in front of the cabinet, I immediately knew what happened, I lost the HF driver.
The tops are :
Yammy DSR112, the plate amp have all the DSP and limiting , so why the driver fail?
Metal fatigue, too low XO point (too much LF power), or just too much power.
Factory DSP suppose to prevent any harm to the drivers!
I saw pics on the net where the diaphragm shattered like this or more.
See the pic
Like 8 months ago the original driver died, at that time it you can see the glue of the coil bubbled and more dark suggesting power failure.
But why? I have seen people who play them with the limiter light stuck on ,
And nothing blow.
Do I have a bad plate amp that is outputting DC or not limiting right?
I'm puzzled.
Last Friday gig one of my tops just go dull, so I noticed and when in front of the cabinet, I immediately knew what happened, I lost the HF driver.
The tops are :
Yammy DSR112, the plate amp have all the DSP and limiting , so why the driver fail?
Metal fatigue, too low XO point (too much LF power), or just too much power.
Factory DSP suppose to prevent any harm to the drivers!
I saw pics on the net where the diaphragm shattered like this or more.
See the pic
Like 8 months ago the original driver died, at that time it you can see the glue of the coil bubbled and more dark suggesting power failure.
But why? I have seen people who play them with the limiter light stuck on ,
And nothing blow.
Do I have a bad plate amp that is outputting DC or not limiting right?
I'm puzzled.
Micro horns BOSE 2.5"
- By azazello
- Full Range
- 0 Replies
I cut radio BOSE and used 2 2.5" speakers. Plastic boxes are really micro horns, long about 25". Incredible sound with enough bass.
DIY crossover for replica JBL 4345 horn and tweeter
- By NavnFugl
- Introductions
- 1 Replies
Hello,
I've a pair of replica JBL 4345 which I've been 4-way actively bi-amping with the DEQX Pre-8.
I'd like to add 2 subwoofers to the mix, and that means I'll have to free up 2 of the 8 channels from the Pre-8.
My idea is to make a passive crossover for the horn (JBL LE 85, 8 Ohm) and tweeter (JBL 077, 8 Ohm), and then run them off of 1 amplifier.
Trouble is I don't have any experience with such activities, so I hope someone here can teach me a thing or two to get started.
What I think I know so far is as follows:
From the JBL 4345 manual they state that the crossover frequency from the horn to the tweeter is at 10kHz, 18dB per octave.
I understand that there are different types of crossovers from 1st to 6th order? They have different names along the way?
After reading around a bit I gather that my crossover needs to be a 3rd order (Due to the 18dB?)
Then I used the link below to calculate what I think is correct:
https://www.diyaudioandvideo.com/Calculator/SpeakerCrossover/
And the result is as follows:
In the calculator I had 2 options for a 3rd order, Butterworth and Bessel, what are the differences between these? Which would suit my case the best?
Am I on the right track here? Or is there something I should know about?
How important are the values? Is it okay to be a bit over or under, in case I can't find a capacitor or inductor with the exact value stated?
I hope someone will enlighten me a bit and maybe give some tips if possible.
Best regards,
NavnFugl
I've a pair of replica JBL 4345 which I've been 4-way actively bi-amping with the DEQX Pre-8.
I'd like to add 2 subwoofers to the mix, and that means I'll have to free up 2 of the 8 channels from the Pre-8.
My idea is to make a passive crossover for the horn (JBL LE 85, 8 Ohm) and tweeter (JBL 077, 8 Ohm), and then run them off of 1 amplifier.
Trouble is I don't have any experience with such activities, so I hope someone here can teach me a thing or two to get started.
What I think I know so far is as follows:
From the JBL 4345 manual they state that the crossover frequency from the horn to the tweeter is at 10kHz, 18dB per octave.
I understand that there are different types of crossovers from 1st to 6th order? They have different names along the way?
After reading around a bit I gather that my crossover needs to be a 3rd order (Due to the 18dB?)
Then I used the link below to calculate what I think is correct:
https://www.diyaudioandvideo.com/Calculator/SpeakerCrossover/
And the result is as follows:
In the calculator I had 2 options for a 3rd order, Butterworth and Bessel, what are the differences between these? Which would suit my case the best?
Am I on the right track here? Or is there something I should know about?
How important are the values? Is it okay to be a bit over or under, in case I can't find a capacitor or inductor with the exact value stated?
I hope someone will enlighten me a bit and maybe give some tips if possible.
Best regards,
NavnFugl
New "Oldie" here :-P
- By MikeEcho
- Introductions
- 1 Replies
Hey,
i just revived my home-studio, it was sleeping the last 13 years in containers -.-
I made a lot of electronic music, soundtracks etc, back in the 90ìes^^
I have some old, analog Roland gear, like TB-303, MC-202, TR-606, TR-909,m Alpha Juno 2, Wavestation A/D, etc pp..^^
So i love the warm, fine analog sound, i swear on vinyls, DAT-Tapes, Tube Amps and even Compact Cassettes 🙂
Now, i am on the search for something tube-styled outdoor gear, and th`s the reason, why i am landed in here.
I am in the mid-fifties, but still feel like an never grown Peter-Pan :-D
I love my dogs, motor-sports, and not to forget - Music, Music was my first love, and it would be my last <3
Hope to meet here open minded, helpful people, same as i am!
cheers and hello to all in here
,
Mario (Germany)I
i just revived my home-studio, it was sleeping the last 13 years in containers -.-
I made a lot of electronic music, soundtracks etc, back in the 90ìes^^
I have some old, analog Roland gear, like TB-303, MC-202, TR-606, TR-909,m Alpha Juno 2, Wavestation A/D, etc pp..^^
So i love the warm, fine analog sound, i swear on vinyls, DAT-Tapes, Tube Amps and even Compact Cassettes 🙂
Now, i am on the search for something tube-styled outdoor gear, and th`s the reason, why i am landed in here.
I am in the mid-fifties, but still feel like an never grown Peter-Pan :-D
I love my dogs, motor-sports, and not to forget - Music, Music was my first love, and it would be my last <3
Hope to meet here open minded, helpful people, same as i am!
cheers and hello to all in here
,Mario (Germany)I
Modding JBL Bar 500
- Room Acoustics & Mods
- 4 Replies
I'm no so satisfied with the sound of my JBL 500 Bar and wanted to see if I can do things about it, like building a larger cabinet for the bass. So first I tried to measure the TS parameters of the subwoofer and the dimensions of the original box to model that in WinISD.
The JBL speaker has markings : S260C3C 3Ohms but it's a special reference for that subwoofer
The method I used to calculate the TS Parameters is here : https://sbacoustics.com/wp-content/uploads/2021/01/Measuring-Thiele-Small-parameters.pdf
The method I used to calculate the impedence is here : https://www.tek.com/en/documents/ho...ement-lab-measuring-impedance-and-capacitance
The results are here :
So first I'd like to know what people think of these parameters, did I made any obvious mistake or is someone willing to measure his speaker for comparaison ?
Then I went ahead to measure the enclosure. It's made of 30mm MDF at the bottom and 18mm MDF on the sides. Three faces are covered with damper. The "panel to panel" measurements are: 267mm x 267mm x 350 mm for a volume of 24.95 Liters (without removing the volume of the daming)
The vent is tricky to measure as it's an oval, and conical : The vent section Outside is like this with a section of 4475,2 mm²
The vent section inside is like that with a section of 3191,1 mm² :
As the vent has a 90° angle in the piping, I measured the longest length to be 40 cm
and the short length to be 20 cm.
To summurize :
Vent port outside : 4475,2 mm²
Vent port inside : 3191,1 mm²
Vent long length : 40 cm
Vent short length : 20 cm
It's probably very wrong but if we assume the means, the vent average size is 3833mm² and 30 cm in length
Then in WinISD I entered the following parameters :
I do not know what are Vcd and Dvol or how important (used) they are in the software
When creating an WinISD project I entered the volume of the box : 24.95 Liters, then the vent diameter to get the same average area
Then I played with the tuning frequency in order to have WinISD calculate the vent length that is about the same size as mine : 30 cm
I'm very surprised with the results :
Did JBL really tuned a subwoofer like this and applies heavy DSP filtering ? Is that part of why I feel the JBL Bar 500 sound "Boomy" and not punchy or tight ?
Do you think I can build a larger box to make things a little better ?
Next I'll measure the frequency response of the amplifier within the subwoofer.
EDIT : I wired a 5 Ohms resistor at the output of the subwoofer amplifier module and measured amplitudes with my scope. The soundtrack generates sinusoidal tones with the sample amplitude and is played over bluetooth to the bar.
By measuring the voltage across the resistor I have an image of the gain for the whole system applied to that subwoofer
First observation: When no sound is applied there is a 385kHz sinewave with an amplitude of 1V at the terminals of the amplifier output:
This is probably the operating frequency of the D class H bridge used in this amplifier.
When I play my soundtrack overbluetooth I can plot the amplitude response of the amplifier only on it's resistor load :
We see a huge gain arround 30Hz and a band cut between 44 and 50 Hz.
Frequencies below 25 Hz are rejected by the amplifier DSP
There is a very smooth cutout frequency above 100Hz but the slope is too "weak" in my opinion and could be steeper.
This does not match exactly the spike of amplitude modeled with WinISD but I probably have many errors in my WinISD model.
Now with all these considerations, it seems that if I can build a box with the same speaker, a volume about 100L and a tuning frequency of 15Hz I can have a better low frequency response, and less of a bump at 70Hz. In red is the response with 100L box and a 15Hz tuning
The vent air speed seems to reach crasy high speeds at low frequency, however below 20Hz the JBL amplifier has a large attenuations and the speaker would never have the same excusion at these frequencies. So it might work because these air speeds are never going to be obtained in real world
I could of course make the vent larger, however the 1st port resonance would be too low...
What are your thoughs on my reasoning before I cut any piece of wood please ?
EDIT :
Link1 : https://www.diyaudio.com/community/threads/hack-for-jbl-wireless-subwoofer.413330/
Someone having issues with the amplifier and tries to add a new input to the subwoofer
Link2 : https://www.diyaudio.com/community/threads/jbl-bar-500-sub-no-power.421103/
Somone having issues with the subwoofer power supply
The JBL speaker has markings : S260C3C 3Ohms but it's a special reference for that subwoofer
The method I used to calculate the TS Parameters is here : https://sbacoustics.com/wp-content/uploads/2021/01/Measuring-Thiele-Small-parameters.pdf
The method I used to calculate the impedence is here : https://www.tek.com/en/documents/ho...ement-lab-measuring-impedance-and-capacitance
The results are here :
So first I'd like to know what people think of these parameters, did I made any obvious mistake or is someone willing to measure his speaker for comparaison ?
Then I went ahead to measure the enclosure. It's made of 30mm MDF at the bottom and 18mm MDF on the sides. Three faces are covered with damper. The "panel to panel" measurements are: 267mm x 267mm x 350 mm for a volume of 24.95 Liters (without removing the volume of the daming)
The vent is tricky to measure as it's an oval, and conical : The vent section Outside is like this with a section of 4475,2 mm²
The vent section inside is like that with a section of 3191,1 mm² :
As the vent has a 90° angle in the piping, I measured the longest length to be 40 cm
To summurize :
Vent port outside : 4475,2 mm²
Vent port inside : 3191,1 mm²
Vent long length : 40 cm
Vent short length : 20 cm
It's probably very wrong but if we assume the means, the vent average size is 3833mm² and 30 cm in length
Then in WinISD I entered the following parameters :
I do not know what are Vcd and Dvol or how important (used) they are in the software
When creating an WinISD project I entered the volume of the box : 24.95 Liters, then the vent diameter to get the same average area
Then I played with the tuning frequency in order to have WinISD calculate the vent length that is about the same size as mine : 30 cm
I'm very surprised with the results :
Did JBL really tuned a subwoofer like this and applies heavy DSP filtering ? Is that part of why I feel the JBL Bar 500 sound "Boomy" and not punchy or tight ?
Do you think I can build a larger box to make things a little better ?
Next I'll measure the frequency response of the amplifier within the subwoofer.
EDIT : I wired a 5 Ohms resistor at the output of the subwoofer amplifier module and measured amplitudes with my scope. The soundtrack generates sinusoidal tones with the sample amplitude and is played over bluetooth to the bar.
By measuring the voltage across the resistor I have an image of the gain for the whole system applied to that subwoofer
First observation: When no sound is applied there is a 385kHz sinewave with an amplitude of 1V at the terminals of the amplifier output:
This is probably the operating frequency of the D class H bridge used in this amplifier.
When I play my soundtrack overbluetooth I can plot the amplitude response of the amplifier only on it's resistor load :
We see a huge gain arround 30Hz and a band cut between 44 and 50 Hz.
Frequencies below 25 Hz are rejected by the amplifier DSP
There is a very smooth cutout frequency above 100Hz but the slope is too "weak" in my opinion and could be steeper.
This does not match exactly the spike of amplitude modeled with WinISD but I probably have many errors in my WinISD model.
Now with all these considerations, it seems that if I can build a box with the same speaker, a volume about 100L and a tuning frequency of 15Hz I can have a better low frequency response, and less of a bump at 70Hz. In red is the response with 100L box and a 15Hz tuning
The vent air speed seems to reach crasy high speeds at low frequency, however below 20Hz the JBL amplifier has a large attenuations and the speaker would never have the same excusion at these frequencies. So it might work because these air speeds are never going to be obtained in real world
I could of course make the vent larger, however the 1st port resonance would be too low...
What are your thoughs on my reasoning before I cut any piece of wood please ?
EDIT :
Link1 : https://www.diyaudio.com/community/threads/hack-for-jbl-wireless-subwoofer.413330/
Someone having issues with the amplifier and tries to add a new input to the subwoofer
Link2 : https://www.diyaudio.com/community/threads/jbl-bar-500-sub-no-power.421103/
Somone having issues with the subwoofer power supply
Attachments
Aino gradient - a collaborative speaker project
Ok folks, inspired by the discussions of room acoustics, sound perception and boundary reflections here at diyaudio.com, I hereby start a new thread for a collaboratory speaker project named
Aino gradient
The inspiration to this project is the legendary and revolutionary home stereo speaker by designer Jorma Salmi, the Gradient 1.0 and it's siblings.
History
We will discuss it's design principles and we try to reconstruct and perhaps even go beyond it's performance and sound quality in contemporary domestic room environment.
This is not a commercial project and if we break some patented or otherwise protected things/issues, it is not intential.
The name of the project combines the very popular finnish first name for women (also wife of composer Jean Sibelius) and the concept of sound pressure gradient Sound speed gradient - Wikipedia, the free encyclopedia
The guidelines for development are as follows:
- to create a pair of stereo speakers that makes use of laws of physics, specially room acoustics to:
- minimize the early reflections from boundaries and to
- utilize the floor boundary gain by
- combining controlled directivity and controlled reflections
The means to achieve this are guidelined by the innovative pioneering work of Jorma Salmi, and they are mainly these:
- the bass utilizes a down-firing driver
- the mid is a large dipole tilted upwards
- the tweeter has controlled and quite narrow directivity (cascaded line array), perhaps dipole/bipole radiation
Ladies and gentlemen, start your engines!
Juhazi
EDIT - status Feb. 2025
Minidsp 4x10HD broke 2021, now two 2x4HD units with latest iteration of settings. LR2 acoustic xo
Aino gradient
The inspiration to this project is the legendary and revolutionary home stereo speaker by designer Jorma Salmi, the Gradient 1.0 and it's siblings.
History
We will discuss it's design principles and we try to reconstruct and perhaps even go beyond it's performance and sound quality in contemporary domestic room environment.
This is not a commercial project and if we break some patented or otherwise protected things/issues, it is not intential.
The name of the project combines the very popular finnish first name for women (also wife of composer Jean Sibelius) and the concept of sound pressure gradient Sound speed gradient - Wikipedia, the free encyclopedia
The guidelines for development are as follows:
- to create a pair of stereo speakers that makes use of laws of physics, specially room acoustics to:
- minimize the early reflections from boundaries and to
- utilize the floor boundary gain by
- combining controlled directivity and controlled reflections
The means to achieve this are guidelined by the innovative pioneering work of Jorma Salmi, and they are mainly these:
- the bass utilizes a down-firing driver
- the mid is a large dipole tilted upwards
- the tweeter has controlled and quite narrow directivity (cascaded line array), perhaps dipole/bipole radiation
Ladies and gentlemen, start your engines!
Juhazi
EDIT - status Feb. 2025
Minidsp 4x10HD broke 2021, now two 2x4HD units with latest iteration of settings. LR2 acoustic xo
Power Supply Optimization for Bluetooth Audio System
- By Sigismund
- Power Supplies
- 2 Replies
Hi,
I want to build a bluetooth audio system with an ESP32 + DAC + Class D amplifier. This is the first draft of the project and I would like to discuss it with you before starting real tests, in order to optimize the schematics.
What I would like to discuss in particular is the power supply. The entire assembly will be powered from a 12V voltage source, obviously an SMPS. This voltage goes directly into the power amplifier. Then, the ESP32 module and the DAC must also be powered from the main 12V. And here's the interesting part. I started the power supply chain through a bidirectional LC filter, which must filter in particular the ripple generated by the 5V DC converter on the input, so that it doesn't go into the amplifier. On the converter side, I added dumping with an RC snubber for stability, and on the amplifier side, the dumping is introduced by the amplifier's filter capacitors that have an ESR of 2 x 260mR. The converter drops the voltage from 12V to 4.5V. Then comes another LC filter cell similar to the one on the input, with dumping included. This attenuates by 48 dB at 400kHz (the coverter frequency). From here, it goes into an LDO that powers the ESP32 with 3.3V... And it also goes to the DAC, through an RC filter (since we have low consumption), which increases the attenuation to 83dB, and through a 3.3V LDO that further increases the attenuation to 123 dB ! This is my first attempt at designing LC filters and DC converters, so I need to check it with someone who really knows about this...
What do yoy think ? Is this enough to have a quiet amplifier, without switching interference in the audio band ?
I want to build a bluetooth audio system with an ESP32 + DAC + Class D amplifier. This is the first draft of the project and I would like to discuss it with you before starting real tests, in order to optimize the schematics.
What I would like to discuss in particular is the power supply. The entire assembly will be powered from a 12V voltage source, obviously an SMPS. This voltage goes directly into the power amplifier. Then, the ESP32 module and the DAC must also be powered from the main 12V. And here's the interesting part. I started the power supply chain through a bidirectional LC filter, which must filter in particular the ripple generated by the 5V DC converter on the input, so that it doesn't go into the amplifier. On the converter side, I added dumping with an RC snubber for stability, and on the amplifier side, the dumping is introduced by the amplifier's filter capacitors that have an ESR of 2 x 260mR. The converter drops the voltage from 12V to 4.5V. Then comes another LC filter cell similar to the one on the input, with dumping included. This attenuates by 48 dB at 400kHz (the coverter frequency). From here, it goes into an LDO that powers the ESP32 with 3.3V... And it also goes to the DAC, through an RC filter (since we have low consumption), which increases the attenuation to 83dB, and through a 3.3V LDO that further increases the attenuation to 123 dB ! This is my first attempt at designing LC filters and DC converters, so I need to check it with someone who really knows about this...
What do yoy think ? Is this enough to have a quiet amplifier, without switching interference in the audio band ?
Single Ended KT66 / KT88 6550 Triode Strapped & Ultra Linear
- By Grid01
- Tubes / Valves
- 20 Replies
Attachments
Making a Variac more optimal
- By Sadface
- Power Supplies
- 11 Replies
G'day Guys,
I managed to find a 2KW single phase variac for 100 kiwibucks a wee while back.
https://www.aliexpress.com/item/100...OCdnqQdW&utparam-url=scene:search|query_from:
One of these but without the fuse holder which is problem #1
Problem #2 is the analog meter is pretty poopy. At 230Vac output according to my DMM the analog meter reads 220Vac.
Problem #3 is the connections. Having to wire things in ever time will be a pain in the buttocks.
So my evil plan is to graft a large plastic jiffy box on the front so that I can mount the extra bits to make it more usefull:
Here's the block diagram.
So far I have tested the variac to make sure it works as intended: check.
I checked the accuracy on the built in analog meter as per above. 10Vac out at 230Vac
I also checked the function of the digital meter: much better. 2Vac out at 230Vac
Next up is to start cutting into the jiffy box to mount the goodies.
After that I will need to figure out how to mount the jiffy box to the front of the Variac chassis. Probably rivet nuts.
I managed to find a 2KW single phase variac for 100 kiwibucks a wee while back.
https://www.aliexpress.com/item/100...OCdnqQdW&utparam-url=scene:search|query_from:
One of these but without the fuse holder which is problem #1
Problem #2 is the analog meter is pretty poopy. At 230Vac output according to my DMM the analog meter reads 220Vac.
Problem #3 is the connections. Having to wire things in ever time will be a pain in the buttocks.
So my evil plan is to graft a large plastic jiffy box on the front so that I can mount the extra bits to make it more usefull:
- Fused IEC socket for power in
- A digital meter: https://www.aliexpress.com/item/100...order_list.order_list_main.131.68d61802ltfBqQ
- Illuminated power on switch
- A slimline NZ power socket for the outlet.
Here's the block diagram.
So far I have tested the variac to make sure it works as intended: check.
I checked the accuracy on the built in analog meter as per above. 10Vac out at 230Vac
I also checked the function of the digital meter: much better. 2Vac out at 230Vac
Next up is to start cutting into the jiffy box to mount the goodies.
After that I will need to figure out how to mount the jiffy box to the front of the Variac chassis. Probably rivet nuts.
Thermal measurements for Modushop Galaxy 1GX388 2U chassis
I am planning to use a Modushop Galaxy 1GX388 2U 330 mm by 280 mm by 80 mm chassis for a pair of Zenductor 2 amplifiers. To find out whether the 10 mm thick corrugated sidewall profiles are sufficient as heatsinks for 15 W to 25 W dissipated power per side, I did thermal measurements with a DC power supply, a 100 W 8 Ohm power resistor, and a thermal camera built into my cell phone.
The answer is that the chassis should work as is, i.e. without replacing the side walls with real heatsinks.
I attached the power resistor with a pair of spare M3 screws and nuts (supplied with the chassis) to the center region of the flat middle section of the 2-channel side of the Galaxy sidewall profile, and ran tests at about 18 W and 39 W, both with the wall free standing and as part of the assembled chassis (with the rear panel partially slid in, to leave an opening for the resistor power cables, and the remaining opening mostly blocked against air movement).
Temperatures stabilized after 20-30 minutes, and were lower than expected. From the measured temperature rises, and correcting for the heat loss directly from the resistor body to ambient, I compute a thermal resistance of about 1.4 K/W or °C/W.
Graph of four measurements (two power levels, freestanding and chassis-integrated heatsink):
Ambient temperature (the zero level of the graph above) was about 22°C. Interestingly, the equilibrium temperatures for the heatsink (corrugated 10 mm sidewall) were lower in the chassis than free standing. The increase in effective convection surface, from bolting on the other four panels of the chassis) must outweigh the shielding effect of the case.
Between the second and third measurement series, I installed (slid, with the screws and nuts already in place) the sidewall into the chassis.
Also interesting (to me) is that radiation losses are not negligible. A sidewall (448 cm^2, counting both surfaces, but not the corrugations) at 40°C radiates about 5 W more power into a 22°C room than it absorbs. I chose NOT to correct for radiation, since the effect will be of similar magnitude in the real application of the chassis.
As mentioned, I did correct for the direct convective losses from the power resistor, by measuring the resistor equilibrium temperature of 120 °C (!) at 9.68 W, with convection shielded from the resistor mounting surface (sitting on an insulating surface), giving a thermal resistance of 10.2 K/W.
The thermal resistance from the resistor case to the heatsink computed as about 0.5 K/W, which should be similar to achievable case-to-heatsink resistances for transistors. No thermal compound was used.
Example of a thermal image (equilibrium image for 18 W power, resistor mounted to side wall inside the chassis):
The resistor mounting position 'shines through' to the outside surface; I used the maximum, center temperature as heatsink temperature for my calculations. This choice should give correct results for the estimated case temperature of the device to be cooled. The average heatsink (side wall) temperature will be lower than computed from the effective thermal resistance of 1.4 K/W.
Resistor mounting position:
The answer is that the chassis should work as is, i.e. without replacing the side walls with real heatsinks.
I attached the power resistor with a pair of spare M3 screws and nuts (supplied with the chassis) to the center region of the flat middle section of the 2-channel side of the Galaxy sidewall profile, and ran tests at about 18 W and 39 W, both with the wall free standing and as part of the assembled chassis (with the rear panel partially slid in, to leave an opening for the resistor power cables, and the remaining opening mostly blocked against air movement).
Temperatures stabilized after 20-30 minutes, and were lower than expected. From the measured temperature rises, and correcting for the heat loss directly from the resistor body to ambient, I compute a thermal resistance of about 1.4 K/W or °C/W.
Graph of four measurements (two power levels, freestanding and chassis-integrated heatsink):
Ambient temperature (the zero level of the graph above) was about 22°C. Interestingly, the equilibrium temperatures for the heatsink (corrugated 10 mm sidewall) were lower in the chassis than free standing. The increase in effective convection surface, from bolting on the other four panels of the chassis) must outweigh the shielding effect of the case.
Between the second and third measurement series, I installed (slid, with the screws and nuts already in place) the sidewall into the chassis.
Also interesting (to me) is that radiation losses are not negligible. A sidewall (448 cm^2, counting both surfaces, but not the corrugations) at 40°C radiates about 5 W more power into a 22°C room than it absorbs. I chose NOT to correct for radiation, since the effect will be of similar magnitude in the real application of the chassis.
As mentioned, I did correct for the direct convective losses from the power resistor, by measuring the resistor equilibrium temperature of 120 °C (!) at 9.68 W, with convection shielded from the resistor mounting surface (sitting on an insulating surface), giving a thermal resistance of 10.2 K/W.
The thermal resistance from the resistor case to the heatsink computed as about 0.5 K/W, which should be similar to achievable case-to-heatsink resistances for transistors. No thermal compound was used.
Example of a thermal image (equilibrium image for 18 W power, resistor mounted to side wall inside the chassis):
The resistor mounting position 'shines through' to the outside surface; I used the maximum, center temperature as heatsink temperature for my calculations. This choice should give correct results for the estimated case temperature of the device to be cooled. The average heatsink (side wall) temperature will be lower than computed from the effective thermal resistance of 1.4 K/W.
Resistor mounting position:
For Sale Antek transformers
I have used Antek transformers for sale. Revised price and shipping cost
AS-4220 opens box but never wired up. Asking $40.00 plus actual shipping cost to lower 48 states. SOLD
AS-4432 limited use once then removed. Asking $40.00 plus actual shipping cost to lower 48 states.
AN-5220 used, asking $45.00 plus plus actual shipping cost to 48 lower states
AS-3218 used pull from dual mono amp. Asking $30 each plus actual shipping cost to lower 48 states. Sold
AS-4220 opens box but never wired up. Asking $40.00 plus actual shipping cost to lower 48 states. SOLD
AS-4432 limited use once then removed. Asking $40.00 plus actual shipping cost to lower 48 states.
AN-5220 used, asking $45.00 plus plus actual shipping cost to 48 lower states
AS-3218 used pull from dual mono amp. Asking $30 each plus actual shipping cost to lower 48 states. Sold
Need help understanding bode plot phase shift
- Solid State
- 3 Replies
Hey guys! I have been trying to design my own simple small signal circuits for using in my condenser microphone. I am pretty new to this, but I was able to get some designs that perform well in regards to THD and Bandwidth. However, when I perform an AC analysis, the bode plot that is displayed also shows the phase relationship within a range of frequencies. When I do a search to understand how much phase shift (or what kind of phase shift) I should see, I can't find an answer. There are tons of videos and blogs that show how to measure the phase shift, but none really saying "how much" I should allow in my design. I saw one guy on reddit saying he allows no more than 10 degree shift from zero. So how much phase shift should be allowed in a well designed circuit? Also, will I be able to hear this as long as the shift is distributed evenly throughout the whole "audible" frequency range? I will post some pics of my bode plot from qspice, and maybe somebody can give some feedback on it.
Here is one where the shift seems to be even up to around 25Khz
Question 1 - is this amount of phase shift considered acceptable in (hifi standards)? Or at least professional standards?
Question 2 - is this going to be audible?
Here is another plot with a more complicated situation going on (180 degrees)
This one has some corner frequencies from some inconvienient bypass caps I had to use.
Question - this shift in the low frequencies, is it normal? Will this cause the low end to be cancelled out or distorted?
Thats it, thanks for reading, any feedback would be really helpful.
Here is one where the shift seems to be even up to around 25Khz
Question 1 - is this amount of phase shift considered acceptable in (hifi standards)? Or at least professional standards?
Question 2 - is this going to be audible?
Here is another plot with a more complicated situation going on (180 degrees)
This one has some corner frequencies from some inconvienient bypass caps I had to use.
Question - this shift in the low frequencies, is it normal? Will this cause the low end to be cancelled out or distorted?
Thats it, thanks for reading, any feedback would be really helpful.
YH11068A 10-32V to 45-390V dc/dc - guess the control ICs
- By trobbins
- Power Supplies
- 50 Replies
You may have seen this neat dc/dc available recently, especially given the wide variable B+ setting capability, and quite high power rating, and ability to run off 12VDC.
For low power valve amps (eg. up to 6V6 push-pull) they should make it very convenient to power just from a 12VDC 4-5A plug-pack.
The initial intrigue is what control IC's are used, as the 8-pin packages are defaced.
To help the guessing game, the attached doc has my first pass at a schematic drawing. No doubt I've misinterpreted a few parts, and the IC pin numbers are based on what I think are the pin 1 dimples that haven't been defaced completely.
Some strong power saving pulse skipping is going on, which appears as low frequency ripple at times, and at other times it is just pulse skipping at 70kHz ripple. The FET drain waveform is pretty clean and fast, given the simple pcb and parts. The current sense filter cap ground and IC ground seem a compromise of layout. The turn-on appears to be trying to occur close to a zero-voltage dip. No load loss is pretty good.
http://dalmura.com.au/projects/YH11068A.pdf
Ciao, Tim
For low power valve amps (eg. up to 6V6 push-pull) they should make it very convenient to power just from a 12VDC 4-5A plug-pack.
The initial intrigue is what control IC's are used, as the 8-pin packages are defaced.
To help the guessing game, the attached doc has my first pass at a schematic drawing. No doubt I've misinterpreted a few parts, and the IC pin numbers are based on what I think are the pin 1 dimples that haven't been defaced completely.
Some strong power saving pulse skipping is going on, which appears as low frequency ripple at times, and at other times it is just pulse skipping at 70kHz ripple. The FET drain waveform is pretty clean and fast, given the simple pcb and parts. The current sense filter cap ground and IC ground seem a compromise of layout. The turn-on appears to be trying to occur close to a zero-voltage dip. No load loss is pretty good.
http://dalmura.com.au/projects/YH11068A.pdf
Ciao, Tim
