Simple crossover good enough?
I picked up some speakers recently, an MTM layout which sound quite good, but I’m curious about the crossover design.
The tweeter is a Vifa D20TD-05-06 and there are 2x Vifa C13WG-08-08 wired in parallel for the mid woofer.
The application notes on the tweeter suggest 2nd order with cutoff at 5kHz, but the actual for these ones is first order LC at ~8kHz (0.47 Ohm 5W and 4.7uF Poly in series to the -ve terminal)
I’m wondering if maybe there should be an inductor on the mid/woofer, but the drop off is quite steep after 10kHz so maybe not?
The tweeter is a Vifa D20TD-05-06 and there are 2x Vifa C13WG-08-08 wired in parallel for the mid woofer.
The application notes on the tweeter suggest 2nd order with cutoff at 5kHz, but the actual for these ones is first order LC at ~8kHz (0.47 Ohm 5W and 4.7uF Poly in series to the -ve terminal)
I’m wondering if maybe there should be an inductor on the mid/woofer, but the drop off is quite steep after 10kHz so maybe not?
DIY ultrasonic vinyl cleaner
- Vendor's Bazaar
- 8 Replies
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After a previous modification, this very stable ultrasonic rotary vinyl record cleaning machine is now completed.
I used a geared motor as its rotational power.
Ultrasonic cleaning can deep clean the record very clean, but it will not damage the vinyl record.
The machine can be set to a timer and can clean a set of records in about 20 minutes.
After a previous modification, this very stable ultrasonic rotary vinyl record cleaning machine is now completed.
I used a geared motor as its rotational power.
Ultrasonic cleaning can deep clean the record very clean, but it will not damage the vinyl record.
The machine can be set to a timer and can clean a set of records in about 20 minutes.
Vintage DAC MP1936 production
- By wyqgyn
- Vendor's Bazaar
- 0 Replies
I think some friends have seen the previous post because he was very confused. I think I will reorganize and send it to him. This is a very old DAC, with a price of $200 per unit back then. Because it is the first generation chip for recording magnetic tapes. So he is very valuable. He works great and can recall warm vintage sounds. You can purchase PCB boards and ship them from China. If you are a friend of the European Union. Please provide the IOSS number, which consists of IM and 10 digits. The mailing time is about 10 days. All PCBs consist of four parts: audio input board, format conversion board, DAC decoding board, and power board. You can play app content through a Bluetooth chip (purchased in China, manufactured in Shenzhen), or use CS8412 coaxial to play CD content. COMBO384 can also be used to connect to a computer for playback, and there is also an external input IIS interface for connecting to Philips turntable playback. I will provide Taobao product connections. You can use Taobao's overseas warehouse to purchase. If you need assembly instructions and BOM list, please send an email application: 410746700@qq.com
Production of DAC1136/DA73/DA726 Original DAC Modules
- By wyqgyn
- Vendor's Bazaar
- 3 Replies
I am very honored to have purchased 2 DAC726 chips, which are identical to DAC1136 and DAC73. These are chips from a long time ago. A chip used to record cassette tapes for opening machines. Today I designed a DAC audio decoder that works with this chip. He works great and can recall warm vintage sounds. You can purchase PCB boards and ship them from China. If you are a friend of the European Union. Please provide the IOSS number, which consists of IM and 10 digits. The mailing time is about 10 days. All PCBs consist of four parts: audio input board, format conversion board, DAC decoding board, and power board. You can play app content through a Bluetooth chip (purchased in China, manufactured in Shenzhen), or use CS8412 coaxial to play CD content. COMBO384 can also be used to connect to a computer for playback, and there is also an external input IIS interface for connecting to Philips turntable playback. I will provide Taobao product connections. You can use Taobao's overseas warehouse to purchase. If you need assembly instructions and BOM list, please send an email application: 410746700@qq.com
Bottlehead Markaudio Alpair 5.3 Pipette ML-Voigt
- By planet10
- Full Range
- 14 Replies
https://bottlehead.com/product/pipette-speaker-kit/
Smaller than it looks. About the size of a microTower
dave
BASEFACE 1.4D Chinese Clone distortion issue
Hi,
I’m working on a clone BASSFACE class D amplifier that was brought in with a burnt-out power supply and a dead output section.
It’s using 10 IRF260Ns for its output.
After fixing the power supply, I noticed the drive waveform on the output had a step on the turn-on, and the low-side FETs were running hot without a load at idle.
I changed the driver transistors from 2316, 916 to 2073, 940 respectively, and doing so solved the problem with the drive waveform. However, the amplifier was getting distortion well before the clipping point. The driver transistors on the low side, especially the 2073, were also running hot when I did this. I switched back to the original drivers to see if the distortion was also present with them fitted, and indeed it was, and it was much worse.
I also tried leaving the 2073, 940 on the high side and the original transistors on the low side, which was somewhat better. I also tried other transistors like 649, 669, and the results were much worse.
Any idea on what is causing this and how I can fix it?
Any help would be greatly appreciated. (I’m kind of new to fixing class D amps 😅)
Also, the rail voltage is 180 peak-to-peak.
I’m working on a clone BASSFACE class D amplifier that was brought in with a burnt-out power supply and a dead output section.
It’s using 10 IRF260Ns for its output.
After fixing the power supply, I noticed the drive waveform on the output had a step on the turn-on, and the low-side FETs were running hot without a load at idle.
I changed the driver transistors from 2316, 916 to 2073, 940 respectively, and doing so solved the problem with the drive waveform. However, the amplifier was getting distortion well before the clipping point. The driver transistors on the low side, especially the 2073, were also running hot when I did this. I switched back to the original drivers to see if the distortion was also present with them fitted, and indeed it was, and it was much worse.
I also tried leaving the 2073, 940 on the high side and the original transistors on the low side, which was somewhat better. I also tried other transistors like 649, 669, and the results were much worse.
Any idea on what is causing this and how I can fix it?
Any help would be greatly appreciated. (I’m kind of new to fixing class D amps 😅)
Also, the rail voltage is 180 peak-to-peak.
Behringer UCA202: Fixing the Low Frequency Cross-talk
- By bolserst
- Equipment & Tools
- 25 Replies
Attachments
Heater Wiring - the Good the Bad and the Ugly
- By nazaroo
- Tubes / Valves
- 286 Replies
looking over photos of DIY projects on the net, and hearing the many stories about hum, makes me want to offer some observations that might help amateur builders.
Understanding the problem of tube heaters and hum is the first step toward ensuring your wiring job will be good enough to give happy results (no hum).
(1) The heater supply is usually A.C. (alternating current), a 50 or 60 cycle voltage taken from a winding off of the power-supply transformer. As such, it is usually more or less a sine-curve (but often with additional components, harmonics), but can actually appear as gross as a sawtooth depending upon the quality of your line voltage.
(2) For hi-fi and musical applications, the heater lines unfortunately provide a way in for noise from the mains (random hash, transients), and also radio frequency noise (RF), because the wires can also act as antennae, picking up noise from nearby motors and other equipment.
(3) So even if you don't convert your Alternating Current (A.C.) power to Direct Current (D.C.), you will still want to have some filtering and protection from line and radio noise.
(4) Also, if you don't convert to D.C., the 60 cycle A.C. hum will leak into other nearby circuits through the electromagnetic field coming off the heater wires, unless you take some precautions.
(5) As well, noise from other parts of the amp (the High Voltage HV supply, the screen supply and bias supplies) can also pick up and inject noise back into the heater lines.
(6) Many people don't bother to convert A.C. to D.C. for the heaters, and so other methods must be applied to minimize hum and noise. This is sometimes a cheaper solution.
In any case, hum and noise remains a problem with amplifier circuits, so basic strategies should be used.
Regardless of whether or not you convert A.C. to D.C. (removing most of the hum), the Mains coming into the amp should be filtered and/or isolated from line noise. This can be done with a basic capacitor network on the lines.
It can be built into the line plug:
-----------------------------------------------------
Next, comes the layout of the heater wiring itself.
(1) The A.C. supply wires are twisted together, to collapse and minimize the field around each. At the same time as current flows in one direction on one line, it is returning in the opposite direction on the other line, and the two fields interact and cancel each other out.
(2) But there is ANOTHER reason why the wires are twisted together, which is often forgotten or neglected: It also stiffens the delivery system and minimizes movement of the wires. What movement? Any motion in a wire carrying current, or in a magnetic field generates a signal, or creates a coupling field. The motion can be very small, almost invisible, as in a guitar or violin string. It will still be very significant here.
The practice of twisting wires is also done to greatly stiffen them, minimizing motion and coupling fields.
(3) This is also the reason why SOLID wire (such as 18 to 14 gauge) should be used for heater leads. In fact, any and all electrical activity has an impact on all metal in the area, and in case you haven't guessed it, will also cause physical forces of motion on the wires. Here we DON'T want flexibility, but rather stiffness.
If you doubt this, or think it is insignificant,
try loosening the bracing bolts on your power transformer,
and listening to the horrible vibrating rattles as the E-I sections bounce around.
(4) Getting back to the theory behind twisting the wires, We want to recognise also that the number of twists is also strongly related to the DISTANCE to the next object that might pick up the signal, by the Inverse Square Law:
Quote:
"The circuit is essentially a coreless electromagnet with only a single turn of wire. By twisting the wires, we produce many small electromagnets, instead of one large one. Furthermore, these many small magnets are pointing in alternating directions. If we were very close to one of these magnets, we could still detect it, but once we are a small distance away, the adjacent opposing magnets will cancel it out (figure 3)."
Thus we want as many twists as possible (per inch), to minimize the proximity effect to other nearby objects.
On the other hand, if you twist the wires too tight, you can also short them or break them or weaken them to the point where they generate resistance and heat unevenly, so there is a limit to how much you can coil / twist the wires before you risk damaging them.
Now we are ready to understand why many seemingly good efforts at heater-wire dressing fail.
The hum is directly related to distance:
(1) The most sensitive components are the ones closest to the heater wire. That would be the area right around the socket! This is typically where the twisting-dressing technique is done the most poorly and sloppily!
(2) Wires at a right-angle to the heater-wire are the least sensitive to hum. Often wires and components are laid out badly in regard to this obvious issue: orientation.
(3) Other components may or may not be more or less sensitive to heater hum depending on orientation. THERE ARE NO general rules for this. For instance, its a bit tricky to orient a coil (or a cap!) for minimum hum, because it has a 3-dimensional field! Some components will be sensitive in ANY orientation, and must be shielded.
Understanding the problem of tube heaters and hum is the first step toward ensuring your wiring job will be good enough to give happy results (no hum).
(1) The heater supply is usually A.C. (alternating current), a 50 or 60 cycle voltage taken from a winding off of the power-supply transformer. As such, it is usually more or less a sine-curve (but often with additional components, harmonics), but can actually appear as gross as a sawtooth depending upon the quality of your line voltage.
(2) For hi-fi and musical applications, the heater lines unfortunately provide a way in for noise from the mains (random hash, transients), and also radio frequency noise (RF), because the wires can also act as antennae, picking up noise from nearby motors and other equipment.
(3) So even if you don't convert your Alternating Current (A.C.) power to Direct Current (D.C.), you will still want to have some filtering and protection from line and radio noise.
(4) Also, if you don't convert to D.C., the 60 cycle A.C. hum will leak into other nearby circuits through the electromagnetic field coming off the heater wires, unless you take some precautions.
(5) As well, noise from other parts of the amp (the High Voltage HV supply, the screen supply and bias supplies) can also pick up and inject noise back into the heater lines.
(6) Many people don't bother to convert A.C. to D.C. for the heaters, and so other methods must be applied to minimize hum and noise. This is sometimes a cheaper solution.
In any case, hum and noise remains a problem with amplifier circuits, so basic strategies should be used.
Regardless of whether or not you convert A.C. to D.C. (removing most of the hum), the Mains coming into the amp should be filtered and/or isolated from line noise. This can be done with a basic capacitor network on the lines.
It can be built into the line plug:
-----------------------------------------------------
Next, comes the layout of the heater wiring itself.
(1) The A.C. supply wires are twisted together, to collapse and minimize the field around each. At the same time as current flows in one direction on one line, it is returning in the opposite direction on the other line, and the two fields interact and cancel each other out.
(2) But there is ANOTHER reason why the wires are twisted together, which is often forgotten or neglected: It also stiffens the delivery system and minimizes movement of the wires. What movement? Any motion in a wire carrying current, or in a magnetic field generates a signal, or creates a coupling field. The motion can be very small, almost invisible, as in a guitar or violin string. It will still be very significant here.
The practice of twisting wires is also done to greatly stiffen them, minimizing motion and coupling fields.
(3) This is also the reason why SOLID wire (such as 18 to 14 gauge) should be used for heater leads. In fact, any and all electrical activity has an impact on all metal in the area, and in case you haven't guessed it, will also cause physical forces of motion on the wires. Here we DON'T want flexibility, but rather stiffness.
If you doubt this, or think it is insignificant,
try loosening the bracing bolts on your power transformer,
and listening to the horrible vibrating rattles as the E-I sections bounce around.
(4) Getting back to the theory behind twisting the wires, We want to recognise also that the number of twists is also strongly related to the DISTANCE to the next object that might pick up the signal, by the Inverse Square Law:
Quote:
"The circuit is essentially a coreless electromagnet with only a single turn of wire. By twisting the wires, we produce many small electromagnets, instead of one large one. Furthermore, these many small magnets are pointing in alternating directions. If we were very close to one of these magnets, we could still detect it, but once we are a small distance away, the adjacent opposing magnets will cancel it out (figure 3)."
Thus we want as many twists as possible (per inch), to minimize the proximity effect to other nearby objects.
On the other hand, if you twist the wires too tight, you can also short them or break them or weaken them to the point where they generate resistance and heat unevenly, so there is a limit to how much you can coil / twist the wires before you risk damaging them.
Now we are ready to understand why many seemingly good efforts at heater-wire dressing fail.
The hum is directly related to distance:
(1) The most sensitive components are the ones closest to the heater wire. That would be the area right around the socket! This is typically where the twisting-dressing technique is done the most poorly and sloppily!
(2) Wires at a right-angle to the heater-wire are the least sensitive to hum. Often wires and components are laid out badly in regard to this obvious issue: orientation.
(3) Other components may or may not be more or less sensitive to heater hum depending on orientation. THERE ARE NO general rules for this. For instance, its a bit tricky to orient a coil (or a cap!) for minimum hum, because it has a 3-dimensional field! Some components will be sensitive in ANY orientation, and must be shielded.
Level shifter using pentode and schade feedback?
- By Tjj226
- Tubes / Valves
- 11 Replies
Hello all. I am working on an OTA, OTL, OCL, OCD : P headphone amp for a friend. He loves his HD800s and the impedance never drops below 300 ohms, so I have the following circuit idea.
We have a couple problems with this circuit. 1: I would need to interface the incoming ac signal with a circuit that is sitting at ~ -155v 2: The input capacitance of the 4P1Ls would be pretty high and require a fairly beefy driver.
Both requirements can be solved separately, however, is there a way were we can kill two birds with 1 stone? Short answer? Maybe. I'm not really sure and I could use some help.
Here is my test circuit. The idea is to create a cathode follower where the output sits at ~ -155v. The signal is fed to G2 instead of G1. This allows G2 to remain at ground potential whilst G1 and the cathode can be shifted down towards the negative supply rail. Finally, I am trying to incorporate schade feedback in order to have triode like performance at the output.
In this circuit the cathode does sit at the correct potential! Yay. Level shifting achieved!
Only 1 small problem. I hardly get any output signal. Where I would expect to get nearly 1v out (0.95v ish), I only get 6mv out 😢
I am hoping some of you might be able to enlighten me on what I might be missing here.
We have a couple problems with this circuit. 1: I would need to interface the incoming ac signal with a circuit that is sitting at ~ -155v 2: The input capacitance of the 4P1Ls would be pretty high and require a fairly beefy driver.
Both requirements can be solved separately, however, is there a way were we can kill two birds with 1 stone? Short answer? Maybe. I'm not really sure and I could use some help.
Here is my test circuit. The idea is to create a cathode follower where the output sits at ~ -155v. The signal is fed to G2 instead of G1. This allows G2 to remain at ground potential whilst G1 and the cathode can be shifted down towards the negative supply rail. Finally, I am trying to incorporate schade feedback in order to have triode like performance at the output.
In this circuit the cathode does sit at the correct potential! Yay. Level shifting achieved!
Only 1 small problem. I hardly get any output signal. Where I would expect to get nearly 1v out (0.95v ish), I only get 6mv out 😢
I am hoping some of you might be able to enlighten me on what I might be missing here.
Designing a "tapered" port?
- By fredygump
- Subwoofers
- 9 Replies
I've seen subwoofer designs where the port has a very restricted center section, and gradually tapers towards both ends. Sometimes they have an almost elliptical flare at the exit. I don't know what they are called, so if you know what they are called, that'd be a big help!
For the record, I don't mean a straight port with flared ends.
Examples are Genelec and their LSE subs, and I have seen pro audio speakers that use ports like this also.
On the Genelec, I suspect the restriction in the middle of the port reduces turbulence, since the port follows an arc. And on the pro audio side, I think maybe it allows a shorter port length while minimizing port noise/ resonance?
I'm asking because I built a radius port awhile back, and now I am interested in trying to improve the design. But I was just guessing, and I don't know the theory behind such a port.
The port I designed has a 10% restriction in the center. To determine port length, I made the inner and outer surfaces the length that VituixCAD calculated. (I used the length of the surfaces based on the realization that air flow will "stick" to those surfaces.)
My assumption about a radius design is that there will be turbulence as air reverses direction rapidly while trying to follow an arc. So my intuition says that restricting the port cross section in the middle section compresses the air, reducing this turbulence.
Questions I'd like to answer:
-Are my thoughts even remotely close to being accurate?
-How much restriction can I add before hurting the port's output?
-Do I need a specialized tool to calculate this type of port, or can I start with a calculation for a straight port?
-To achieve a desired tuning frequency, do I have to keep the port's internal volume the same as what a calculator says?
-Or does the restriction in the middle of the port offset the reduction in internal volume?
I will probably do some experiments at some point, but I don't know when that will happen. I'm in the middle of a long term project that deserves my full attention, so if you see me doing subwoofer testing, you will know that I am being irresponsible... 😛
For the record, I don't mean a straight port with flared ends.
Examples are Genelec and their LSE subs, and I have seen pro audio speakers that use ports like this also.
On the Genelec, I suspect the restriction in the middle of the port reduces turbulence, since the port follows an arc. And on the pro audio side, I think maybe it allows a shorter port length while minimizing port noise/ resonance?
I'm asking because I built a radius port awhile back, and now I am interested in trying to improve the design. But I was just guessing, and I don't know the theory behind such a port.
The port I designed has a 10% restriction in the center. To determine port length, I made the inner and outer surfaces the length that VituixCAD calculated. (I used the length of the surfaces based on the realization that air flow will "stick" to those surfaces.)
My assumption about a radius design is that there will be turbulence as air reverses direction rapidly while trying to follow an arc. So my intuition says that restricting the port cross section in the middle section compresses the air, reducing this turbulence.
Questions I'd like to answer:
-Are my thoughts even remotely close to being accurate?
-How much restriction can I add before hurting the port's output?
-Do I need a specialized tool to calculate this type of port, or can I start with a calculation for a straight port?
-To achieve a desired tuning frequency, do I have to keep the port's internal volume the same as what a calculator says?
-Or does the restriction in the middle of the port offset the reduction in internal volume?
I will probably do some experiments at some point, but I don't know when that will happen. I'm in the middle of a long term project that deserves my full attention, so if you see me doing subwoofer testing, you will know that I am being irresponsible... 😛
Revisiting XOC1 TH18 EPA Mod 30Hz with SBA 18SW1900D
- By maxolini
- Subwoofers
- 7 Replies
Guys,
does anyone have the plan for the moded XOC1 TH18 made by EPA
i was looking on my SUB plans folders and cant find it
while browsing trough my HR saved screens i found the EPA screen and when on it
i simmed some drivers and the
it can take 1kw to hit xmax at 30hz
the sompresion ratio is almost 3:1
does a BL of 28 for that driver will cut
not risking the driver cone get shredded to pieces ?
SBA 18SW1900D
does anyone have the plan for the moded XOC1 TH18 made by EPA
i was looking on my SUB plans folders and cant find it
while browsing trough my HR saved screens i found the EPA screen and when on it
i simmed some drivers and the
SB Audience Nero-18SW1900D 18"
caught my eye on how it sims ,looks goodit can take 1kw to hit xmax at 30hz
the sompresion ratio is almost 3:1
does a BL of 28 for that driver will cut
not risking the driver cone get shredded to pieces ?
SBA 18SW1900D
What is purpose of resistor in the circuit
- Solid State
- 15 Replies
Hello All
Refer to picture below.
Could you let me know what is purpose of resistor in the red circle ?
I guess this may be feedback to Vbe it is correct ?
Thank you.
Best Regard
Refer to picture below.
Could you let me know what is purpose of resistor in the red circle ?
I guess this may be feedback to Vbe it is correct ?
Thank you.
Best Regard
Antek AN-5435 Transformer For Sale
Brand New Antek AN-5435 500VA 35V transformer for sale. Purchased for a project that I sold off before power up. Never had power applied or even wires attached, all wires as shipped. $65 shipped in the CONUS.
Compact KT88 SET monoblocks
- By Gmichael52
- Tubes / Valves
- 11 Replies
Here’s one of the compact KT-88 SET’s I built. I’ve built some crazy amps so I don’t like to post up project builds that are a failure.. and I’ve built many.
Doing some QA on this one. This one is quite the joy. Ran out of copper bar stock, so this one took the lead and finished it up.
More pics to come.
Doing some QA on this one. This one is quite the joy. Ran out of copper bar stock, so this one took the lead and finished it up.
More pics to come.