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.
Dual 701 turntable assembly problems
- By Jan Dupont
- Analogue Source
- 44 Replies
Hi All
Servicing a Dual 701 turntable and detached the Cam wheel the wrong way.
Now I got these two small parts (#146 Pawl and #145 Tension spring)
And have no idea how to fit these. Service manual doesn't give any help, so do we have a Dual expert here?
I think it must be close to this, but where to attach the spring?
Any help appriciated
Servicing a Dual 701 turntable and detached the Cam wheel the wrong way.
Now I got these two small parts (#146 Pawl and #145 Tension spring)
And have no idea how to fit these. Service manual doesn't give any help, so do we have a Dual expert here?
I think it must be close to this, but where to attach the spring?
Any help appriciated
Attachments
Dayton Reference RS270-8 10" Woofers (almost new in original boxes)
For sale: One pair, Dayton RS270-8 10" woofers. Woofers have been briefly mounted to test, but have less than 10 hours of use.
One of them has a cone blemish- the other is in cosmetic perfect condition. Spiders are perfectly flat (no cone sag).
Selling for $130.00 for the pair, plus shipping.
Would accept up to two Dayton Audio DCS165-4 6.5" subwoofer drivers and/or up to four Dayton Epique E180HE 7" passive radiators in partial or total trade toward these.
Located in Kennesaw GA. Local pickup definitely available!
If replying to this- please also send an email to gwaters@inbox.com, as I don't get to check in here as much as I used to...
Thanks!
Regards,
Gordon.
One of them has a cone blemish- the other is in cosmetic perfect condition. Spiders are perfectly flat (no cone sag).
Selling for $130.00 for the pair, plus shipping.
Would accept up to two Dayton Audio DCS165-4 6.5" subwoofer drivers and/or up to four Dayton Epique E180HE 7" passive radiators in partial or total trade toward these.
Located in Kennesaw GA. Local pickup definitely available!
If replying to this- please also send an email to gwaters@inbox.com, as I don't get to check in here as much as I used to...
Thanks!
Regards,
Gordon.
For Sale High-end DIY speaker project (Eclipse 1238R, Madisound 8252R, Focal 7V313, SEAS 27TFFC, enclosures
For sale: Very high-end DIY speaker system, I helped design and build about 20 years ago. It is a project- as it will require some re-building.
This system is four-way, tri-amped, with passive crossovers (included) between the midrange and tweeter. Drivers per channel are: tweeter: 1- SEAS 27TFFC, midrange: 1- Focal 7V313, mid-woofers: 4- Madisound 8252R 8", subwoofers: 2- Eclipse W1238R.
The cabinets for the mid/tweeter and midbasses are Woodstyle, from Madisound. The mid-high cabinets are sealed, and the midbass cabinets have one Dynaudio aperiodic Variovent in the rear of each cabinet. The mid-tweeter cabinets are in good shape, including grills, but the midbass cabinets will require some repair, as there is some damage to the plinths of the cabinets. The cabinets themselves are in good shape, save for one missing grill- but the plinths have gotten slightly wet in storage, and will need some remediation. The cabinets for the subwoofers were built-into the wall of the original installation- and were not save-able, when this system was removed. I do have the specs for the subwoofer cabinets.
This system, as mentioned, was tri-amped. We originally used a Madisound Sledgehammer 3-way active crossover and a couple of four-band parametric EQs on the bass and midbass- but, all of this function could be much more easily accomplished now, by something like a DBX Driverack. That's what I would recommend, wholeheartedly. I can give the buyer a good starting point for the crossover settings in the Driverack (active crossover points of roughly 50Hz and 400Hz). The original passive crossovers (2.6KHz) between midrange and tweeters are also provided.
I don't know of any practical way to ship this- it's available in the northern Atlanta GA USA area (I'm in Kennesaw GA, but can drive to meet within reason- I have a pickup truck with covered camper shell).
Asking $600 for the lot.
This, frankly, was one of the finest audio systems I have personally encountered anywhere- and that includes very high-end systems I have worked with, that have price tags of into the seven-digit-dollar amounts. I would really enjoy having someone put it back into use...
Thanks!
Regards,
Gordon.
This system is four-way, tri-amped, with passive crossovers (included) between the midrange and tweeter. Drivers per channel are: tweeter: 1- SEAS 27TFFC, midrange: 1- Focal 7V313, mid-woofers: 4- Madisound 8252R 8", subwoofers: 2- Eclipse W1238R.
The cabinets for the mid/tweeter and midbasses are Woodstyle, from Madisound. The mid-high cabinets are sealed, and the midbass cabinets have one Dynaudio aperiodic Variovent in the rear of each cabinet. The mid-tweeter cabinets are in good shape, including grills, but the midbass cabinets will require some repair, as there is some damage to the plinths of the cabinets. The cabinets themselves are in good shape, save for one missing grill- but the plinths have gotten slightly wet in storage, and will need some remediation. The cabinets for the subwoofers were built-into the wall of the original installation- and were not save-able, when this system was removed. I do have the specs for the subwoofer cabinets.
This system, as mentioned, was tri-amped. We originally used a Madisound Sledgehammer 3-way active crossover and a couple of four-band parametric EQs on the bass and midbass- but, all of this function could be much more easily accomplished now, by something like a DBX Driverack. That's what I would recommend, wholeheartedly. I can give the buyer a good starting point for the crossover settings in the Driverack (active crossover points of roughly 50Hz and 400Hz). The original passive crossovers (2.6KHz) between midrange and tweeters are also provided.
I don't know of any practical way to ship this- it's available in the northern Atlanta GA USA area (I'm in Kennesaw GA, but can drive to meet within reason- I have a pickup truck with covered camper shell).
Asking $600 for the lot.
This, frankly, was one of the finest audio systems I have personally encountered anywhere- and that includes very high-end systems I have worked with, that have price tags of into the seven-digit-dollar amounts. I would really enjoy having someone put it back into use...
Thanks!
Regards,
Gordon.
For Sale Amber 3501a Audio Distortion and Noise Measuring System
This is a really nice condition Amber 3501a that I bought a few years back to fill a gap while soing some maintenance on my other analyzers. The previous owner adapted this unit for his convenience when working in the field and at his shop on audio amplifiers. He changed the BNC generator output jack to an RCA jack, and added banana jacks for easy hookup of amplifier outputs. To switch between channels for taking measurements, he changed the front grounded/ungrounded input switch to switch between banana jacks (Input 1 and Input 2).
Here it is testing a buffer/preamp with very low output showing good sensitivity. I've used it for testing a few Adcom amps and it worked well, but as you can see from the unit beneath the Amber, I've moved into a different type of analyzer, and still have my early HP analyzers, so this is ready to move to the next person who wants a quick and easy way of testing functionality and performance without going into a more expensive system, or a more fiddly/time consuming approach like a soundcard and REW. Actually, I have those systems as well, and each has its own place. I find these self-contained distortion analyzers to be best for initial function/performance testing of units I'm evaluating prior to and after repairs.
When I bought it I cleaned all the rotary switches and board connections, inspected the boards and terminations, tightened various fasteners, and re-painted the front corner brackets.
How about $350 plus shipping and PP fees (CONUS only, please)? I can provide two PDF manuals for the buyer - the slightly different 3501 and for this 3501a. Thank you.
Here it is testing a buffer/preamp with very low output showing good sensitivity. I've used it for testing a few Adcom amps and it worked well, but as you can see from the unit beneath the Amber, I've moved into a different type of analyzer, and still have my early HP analyzers, so this is ready to move to the next person who wants a quick and easy way of testing functionality and performance without going into a more expensive system, or a more fiddly/time consuming approach like a soundcard and REW. Actually, I have those systems as well, and each has its own place. I find these self-contained distortion analyzers to be best for initial function/performance testing of units I'm evaluating prior to and after repairs.
When I bought it I cleaned all the rotary switches and board connections, inspected the boards and terminations, tightened various fasteners, and re-painted the front corner brackets.
How about $350 plus shipping and PP fees (CONUS only, please)? I can provide two PDF manuals for the buyer - the slightly different 3501 and for this 3501a. Thank you.
Whammy Custom PCB + Dual Mono PSU + Muses 72320 Vol Control
Another day, another finding,
for sale is a set of custom PCBs for Wayne Colburn's Whammy, just a different approach (and a bit better sounding as I listened to about 3 versions of it). Designer of the set is a very professional DIYAudio member who puts a lot of passion into his routings and PCB making. The special thing is, you can put the Amplifier backpack on the PSU with appropriate Spacers and thus fit it into a 3U Galaxy Case from ModuShop (230x280), by using L-shaped aluminum heatspreads you can dissipate the output transistor heat directly to case without the need of a dedicated heatsink. The other thing making it special is the PSU (or UPS how the designer called it). It's a dual mono cap multiplier with HF and LF filters, thus very silent ;-). The amp board is nearly fully stuffed, only 4 resistors and a few caps missing. Stuffed with original BB OPA604. The muses vol. Control can be directly supplied by the PSU and does not need any special PSU
Consists of:
I paid a total of around 230€ for everything,
asking 200€ + shipping + PP fees.
A built variant on bench for testing before it went into the enclosure (I know its dark pictures, just you get an image of how its backpacked).
for sale is a set of custom PCBs for Wayne Colburn's Whammy, just a different approach (and a bit better sounding as I listened to about 3 versions of it). Designer of the set is a very professional DIYAudio member who puts a lot of passion into his routings and PCB making. The special thing is, you can put the Amplifier backpack on the PSU with appropriate Spacers and thus fit it into a 3U Galaxy Case from ModuShop (230x280), by using L-shaped aluminum heatspreads you can dissipate the output transistor heat directly to case without the need of a dedicated heatsink. The other thing making it special is the PSU (or UPS how the designer called it). It's a dual mono cap multiplier with HF and LF filters, thus very silent ;-). The amp board is nearly fully stuffed, only 4 resistors and a few caps missing. Stuffed with original BB OPA604. The muses vol. Control can be directly supplied by the PSU and does not need any special PSU
Consists of:
- Whammy Board nearly fully assembled
- A set of nicely matched 2SK2013 / 2SJ313 Output Transistors
- Dual Mono PSU cap mulitplier PSU
- Muses 72320 Vol. Attenuator
I paid a total of around 230€ for everything,
asking 200€ + shipping + PP fees.
A built variant on bench for testing before it went into the enclosure (I know its dark pictures, just you get an image of how its backpacked).
NJW Symasym - potential GB Interest
- By Fabian85
- Group Buys
- 7 Replies
This will probably the last chance to get Rudi_ratlos latest iteration of Symasym boards as it will also be one of my last group buys for this. It's a great sounding amp, check on Forums for more information about it.
It's the latest version with 2 pairs of NJW output transistors. houses a speaker protect circuit (that does not have to be populated, but why wouldn't you). Board size is about 215x95mm. The board shares the option to power the front end of the circuit with a dedicated PSU by setting jumpers.
Price will depend highly on several factors as:
I ran it through several well known PCB manufacturers and I came to about 14-15$ for a single board, not including taxes.
Please share your thoughts and interest that way. If enough people are interested, I will quote for the most requested.
#1 DIYAudio Name / Country / Qty of PCBs / Color (Green / Black / Red / something else) / Thickness (1.6 or 2mm) / HASL-Lead free or ENIG
It's the latest version with 2 pairs of NJW output transistors. houses a speaker protect circuit (that does not have to be populated, but why wouldn't you). Board size is about 215x95mm. The board shares the option to power the front end of the circuit with a dedicated PSU by setting jumpers.
Price will depend highly on several factors as:
- Number of interested builders
- 1,6 / 2mm PCB
- Min. is HASL-lead free
- PCB color ;-)
I ran it through several well known PCB manufacturers and I came to about 14-15$ for a single board, not including taxes.
Please share your thoughts and interest that way. If enough people are interested, I will quote for the most requested.
#1 DIYAudio Name / Country / Qty of PCBs / Color (Green / Black / Red / something else) / Thickness (1.6 or 2mm) / HASL-Lead free or ENIG
Increased voltage supply forYamaha SC-02
- By photropik
- Headphone Systems
- 3 Replies
I have one of these Yamaha SC-02 mini guitar practise mixer things. It runs on two 1.2v - 1.5v batteries.
I was thinking of powering with a bank of four 18650s which would sit underneath quite nicely.
I'm wondering if I need to add a regulator, the device appears quite analogue, so I was wondering if upping the voltage to 4.4v would be detrimental to it's functioning.
Posted in headphones because it's designed for headphones, and I use it as a little headphone amp, it even drives my old 2k ohm DT-100 nicely.
I was thinking of powering with a bank of four 18650s which would sit underneath quite nicely.
I'm wondering if I need to add a regulator, the device appears quite analogue, so I was wondering if upping the voltage to 4.4v would be detrimental to it's functioning.
Posted in headphones because it's designed for headphones, and I use it as a little headphone amp, it even drives my old 2k ohm DT-100 nicely.
Digital Control of Attenuation – Repository for DIY
I’m starting this thread in the Pass Labs sub-forum, because I think there is a need for this information here, and because the idea for a digital attenuator came while building the excellent Iron Pre by Zen Mod.
There seems to be interest in a repository for free information pertaining to digital attenuation systems, in particular the Muses family of chips: 72320 and 72323.
Over the years, there have been a number of attenuators available using the Muses products. Some are commercial, but most were developed in-house by DIYers. Therefore, there is likely to exist quite a lot of knowledge in the community about implementing Muses chips.
If it weren't for generous people like Nelson Pass, Wayne Colburn, Zen Mod, Mark Johnson, XRK, 6L6, AKSA, Salas, and many others, our DIY efforts would have looked very different. And since this forum is called diyAudio, we should embrace the culture of sharing. So, in the spirit of DIY, I encourage everyone who can contribute, to share information about digital attenuation, no matter how small.
In this thread we can collaborate and share information for building our own Muses attenuators. Feel free to share your microcontroller code, libraries, schematics, tips, experiences, etc. as well as questions.
I’ll kick off by listing an Arduino library for the Muses72320 by Christoffer Hjalmarsson: github.com/qhris/Muses72320
* New - Updated library to include gain function and also other updated functions: MUSES72323 Library
Muses72320 datasheet
Muses72323 datasheet
Arduino libraries & code (generously supplied by @Nikon1975) - added 23 Sep 2023
Muses72320 Library
Muses72323 Library
Arduino code (full preamp code, including Muses72323) - added 26 Sep 2023
Arduino code for Muses72323 (Muses72323 code only. It compiles, but not tested)
Muses 72323 library for calculating the 16-bit address by @d00dz1
(Also see this thread for more information)
ESP32 code
Muses72320 on ESP
Library for Muses72323 using Soft-SPI as well as Hard-SPI by jpk73 - added 4 May 2024
SSOP32 adapter board. Mouser# 854-AB-SOIC32/SSOP
There seems to be interest in a repository for free information pertaining to digital attenuation systems, in particular the Muses family of chips: 72320 and 72323.
Over the years, there have been a number of attenuators available using the Muses products. Some are commercial, but most were developed in-house by DIYers. Therefore, there is likely to exist quite a lot of knowledge in the community about implementing Muses chips.
If it weren't for generous people like Nelson Pass, Wayne Colburn, Zen Mod, Mark Johnson, XRK, 6L6, AKSA, Salas, and many others, our DIY efforts would have looked very different. And since this forum is called diyAudio, we should embrace the culture of sharing. So, in the spirit of DIY, I encourage everyone who can contribute, to share information about digital attenuation, no matter how small.
In this thread we can collaborate and share information for building our own Muses attenuators. Feel free to share your microcontroller code, libraries, schematics, tips, experiences, etc. as well as questions.
I’ll kick off by listing an Arduino library for the Muses72320 by Christoffer Hjalmarsson: github.com/qhris/Muses72320
* New - Updated library to include gain function and also other updated functions: MUSES72323 Library
Muses72320 datasheet
Muses72323 datasheet
Arduino libraries & code (generously supplied by @Nikon1975) - added 23 Sep 2023
Muses72320 Library
Muses72323 Library
Arduino code (full preamp code, including Muses72323) - added 26 Sep 2023
Arduino code for Muses72323 (Muses72323 code only. It compiles, but not tested)
Muses 72323 library for calculating the 16-bit address by @d00dz1
(Also see this thread for more information)
ESP32 code
Muses72320 on ESP
Library for Muses72323 using Soft-SPI as well as Hard-SPI by jpk73 - added 4 May 2024
SSOP32 adapter board. Mouser# 854-AB-SOIC32/SSOP
Help with low current 12V SMPS design
- By MJC147
- Electronic Design
- 14 Replies
Hi, Im having a go at building a low current 12v 0.4A smps. I need it to be small, and cost effective, and i hope not to have to use any ic’s.
Here is my explanation of the circuit: 220v DC flows in via J1. This 220v is then stepped down by the resistor divider, to under 50v. This <50v powers the switching circuitry
(this low current 50v is just supplying the switching circuitry, it is NOT connected to the output). The switching circuitry switches 220vdc through isolated transformer T1.
Finally, the one and only output of this SMPS on pins 1 & 2 of t1, is completely isolated from the 220v input.
My issue is that Q5 isn't switching, i believe the astable multivibrator is drawing too much current from the 50v voltage divider. What can i do to supply the astable multivibrator.
I could increase the wattage handling of the voltage divider resistors, but to begin with this whole voltage divider method to supply the multivibrator is very inefficient.
I imagine everyone is scared off now.
Here is my explanation of the circuit: 220v DC flows in via J1. This 220v is then stepped down by the resistor divider, to under 50v. This <50v powers the switching circuitry
(this low current 50v is just supplying the switching circuitry, it is NOT connected to the output). The switching circuitry switches 220vdc through isolated transformer T1.
Finally, the one and only output of this SMPS on pins 1 & 2 of t1, is completely isolated from the 220v input.
My issue is that Q5 isn't switching, i believe the astable multivibrator is drawing too much current from the 50v voltage divider. What can i do to supply the astable multivibrator.
I could increase the wattage handling of the voltage divider resistors, but to begin with this whole voltage divider method to supply the multivibrator is very inefficient.
I imagine everyone is scared off now.
Attachments
DIY NEAT IOTA ALPHA project. Anybody know what tweeter to use?
- By norway-diy
- Multi-Way
- 16 Replies
Hi, Im a pretty new to DIY speakers. I have just done a couple of kits before.
Now I want to make a "copy" of the Neat Iota Alpha speakers, I like the look of them and I read a lot of good reviews for such a small speaker.
I have been digging around on the net and found some info. I have the dimensions and the name of the woofer and mid drivers.
But Im struggling with the tweeters.
They use Peerless SDS-P830656 woofers and Peerless HDS-P830870 mid drivers.
The tweeter they use are listed as 50mm EMIT Planar Magnetic, but I cant find them on the internet.
These are very cheap drivers and I find it a bit strange that the price of the speakers from Neat are over 2000 $ here in Norway!
So, do anybody know where I can buy the tweeters they use, or can anybody give me some good advice when it comes to pairing the Peerless drivers with a matching (
ribbon) tweeter?
The Neat speakers are 2.5 way speakers and I will add some pixs here.
I will prob need some help if possible with the X-over, but I did read that they are crossed over at 4k and 80 hz
Hope somebody can help me out here.
B
Now I want to make a "copy" of the Neat Iota Alpha speakers, I like the look of them and I read a lot of good reviews for such a small speaker.
I have been digging around on the net and found some info. I have the dimensions and the name of the woofer and mid drivers.
But Im struggling with the tweeters.
They use Peerless SDS-P830656 woofers and Peerless HDS-P830870 mid drivers.
The tweeter they use are listed as 50mm EMIT Planar Magnetic, but I cant find them on the internet.
These are very cheap drivers and I find it a bit strange that the price of the speakers from Neat are over 2000 $ here in Norway!
So, do anybody know where I can buy the tweeters they use, or can anybody give me some good advice when it comes to pairing the Peerless drivers with a matching (
The Neat speakers are 2.5 way speakers and I will add some pixs here.
I will prob need some help if possible with the X-over, but I did read that they are crossed over at 4k and 80 hz
Hope somebody can help me out here.
B
Linear Audio High-voltage Delay for Tube Amplifiers V4
- By Cetla416a
- Tubes / Valves
- 7 Replies
