Yamaha yst-sw800 power supply questions
- By tonskulus
- Power Supplies
- 0 Replies
Ok I finally managed to fix one of these nice subwoofers. There is something I dont fully understand. Amplifier is capable of 800Watts RMS power. However, the power cord is rated 2.5Amps. The input RFI choke is rated 2.5Amps. Mains transformer has very thin secondary windings, something like 0.5mm diam. How do these withstand such a load?
Power supply is very simple self oscillating SMPS (ZCS/ZVS type?), no controller IC's, only few discrete components. Output voltage is +/-112Volts. Amplifier is also made out of discrete components, Class TD topology.
Yamaha claims:
Power supply has superior load characteristics, minimal noise, higher efficiency and stability.
Power supply holds the voltage and current levels to zero while the decice turns on and off, this reduces noise.
Other advantages include superb sability against power fluctuations.
Yet, so simple smps circuit? Well, it failed and there has been many YST-sw800's having the same issues, main amplifier failed and psu failed.
What I did notice, is that there was many bad solder joints especially on amplifier pcb. One driver (Q1A) transistor was shorted but output fets and other semiconductors were all ok. I changed the driver transistor and fixed all bad solder joints. When I turned the amp on, that very same driver transistor immediately got very hot. Bias current was out of spec, so it had to be failed bias trimmer which I soon changed. Problem solved, amplifier is now very stable and is running cool.
So the original cause of this failure was possibly some bad solderings and/or bad bias trimmer. This caused the amplifier run out of control and, possibly burn the SMPS.
SMPS main transistors (2SC4140) were shorted. Both drivers were shorted and two resistors was burned. I changed these and it fixed the smps. I used BUX98AQ as a replacement type, these are more robust than original 2SC4140's.
So, there is no short circuit or over load protection for SMPS?! Did they choose the cheapest way to make SMPS? 😀
Schematic:
Power supply is very simple self oscillating SMPS (ZCS/ZVS type?), no controller IC's, only few discrete components. Output voltage is +/-112Volts. Amplifier is also made out of discrete components, Class TD topology.
Yamaha claims:
Power supply has superior load characteristics, minimal noise, higher efficiency and stability.
Power supply holds the voltage and current levels to zero while the decice turns on and off, this reduces noise.
Other advantages include superb sability against power fluctuations.
Yet, so simple smps circuit? Well, it failed and there has been many YST-sw800's having the same issues, main amplifier failed and psu failed.
What I did notice, is that there was many bad solder joints especially on amplifier pcb. One driver (Q1A) transistor was shorted but output fets and other semiconductors were all ok. I changed the driver transistor and fixed all bad solder joints. When I turned the amp on, that very same driver transistor immediately got very hot. Bias current was out of spec, so it had to be failed bias trimmer which I soon changed. Problem solved, amplifier is now very stable and is running cool.
So the original cause of this failure was possibly some bad solderings and/or bad bias trimmer. This caused the amplifier run out of control and, possibly burn the SMPS.
SMPS main transistors (2SC4140) were shorted. Both drivers were shorted and two resistors was burned. I changed these and it fixed the smps. I used BUX98AQ as a replacement type, these are more robust than original 2SC4140's.
So, there is no short circuit or over load protection for SMPS?! Did they choose the cheapest way to make SMPS? 😀
Schematic:
Microfarads- Nano Speaker using PS95 and W5-2053
I wanted to share a decent build I finished, what I'm calling the Microfarads!
Project Description:
This is the most challenging smallest speaker I've built to date. Due to the strict enclosure volume restrictions, this is also the most precisely built speaker I've made with each cut toleranced to less than 1/32".
Total internal volume (not air space) is 3 liters including the PS95 sub-enclosure, I was pretty frustrated about some of the nonsensical restrictions on this project initially but ultimately grew to appreciate Ben's sense of neurotic restricted creativity =)
The subwoofer is the Tang Band W5-2053 with 2 Peerless 5.25" per enclosure.
Crossover frequency is about 300hz
Design Goals:
1 - Build a full range speaker capable of solid bass with smooth response to 20kHz
2 - Total internal volume of 3 liters including mid enclosure
3 - Unique striking look
4 - Ensure every possible square inch is covered by a sound radiating diaphragm =)
Driver Selection:
I tried a few different drivers but always knew I'd end up with the W5-2053, this thing is a monster and the bass it puts out from only 3l is astounding. Was an interesting driver to work with as it's response falls off a literal cliff at around 1kHz, so I used that to my advantage in the XO.
I had a pair of PS95's I'd been wanting to try out and was shocked by how good they sounded, so after trying some different drivers I settled on those. They were also welcome with the limited space I had to work with.
Enclosure design:
This was purely determined by 2 factors...driver and PR mounting dimensions and the strict internal volume requirement. As you can see it's all a tight fit.
Precise calculations were made initially using some triangle area calculators to ensure internal volume was at or less than 3l.
Passive Radiators ended up with no weight which resulted in a 56hz tuning frequency, more boosted than I wanted but adding any weight maxed out the excursion that much sooner. I was able to add 15 grams to bring it down to 50 but the passives were straining much sooner, as is the W5 easily over powers 2 5" PR's, really 3 or 4 of these would better keep up with 1 W5.
Another passive radiator issue I dealt with early on was "enclosure walk", using dual opposed passive radiators solves most of that. Also Sorbothane feet in 30 durometer further eliminated any chance of movement.
Enclosure Construction:
Construction is solid mahogany, angled joints are mitered, all glue construction.
I made this CAD (Cardboard Accurate Dimension) to help with the initial concept, I also used it to check test cuts to ensure things were aligning and helping with angle calculations:
Plywood test cut that was perfect, this locked in all my angles on the table saw:
Tape held it all together:
In Mahogany:
I made the cut out of one board to match the grain:
Attaching front baffle:
My cut list:
Test fit:
Clamping and gluing the baffle:
Before I attached the sides I wanted to finalize the mid enclosure, since the PS95 needed no airspace to play to 300hz, I molded a tight fitting fiberglass enclosure.
I started by mounting the driver into a board just like I would in the final enclosure, then I built a makeshift mold using layers of alum foil and masking tape:
Fiberglass matte:
Polyester resin:
Wala, about 5 layers:
Removed from the mold:
Trimmed up and painted:
Built into the mold was a 3/16" Sorbothane disc which creates a CLD treatment to the back of the enclosure, as the driver is screwed down it loads up on this viscoelastic dampening medium and greatly acoustically dampens the mid enclosure. I tested this and it works well:
Mounted, it is attached with silicone adhesive and some screws for good measure:
Time for some sides:
All panels glued and flush, ready for some roundovers:
I didn't have enough room for a full 1" round over like I wanted to do, but fortunately the W5 wouldn't benefit from it, so I developed a way to do a tapered round over using a wedge for the router bearing to ride on:
This created a precise contour that cleared all driver frames.
And all round overs and treatments done:
And a coat of Danish Oil, BOOM! There's the grain!
And after soaking in:
Crossover Design:
I tried many designs including various frequencies and electrical slopes before finalizing on what I have here. I ended up with 18db on the mid and 12 on the sub. Since I was crossing over at 300hz I used an Lpad to not only balance out the more efficient PS95 but also as a baffle step function.
The PS95 also displays break up bad above 15k but it starts around 9k, I implemented a 12db low pass sound 10kHZ which rolled off the top end nicely until it was voiced the way I wanted. Not sibilant but with air and space. Indicators are 18ga, all capacitors are electrolytic except for poly in the PS95 top end roll off and the 1uf listed in the schematic.
I tuned this until it had a flat response but like that the highs just fell flat, despite loving the FR plot it just didn't sound rift, so what sounded best is what's below (near field at about 12" centered on the mid.
Installed, tight fit!
Conclusion:
These were a blast and they've been my go to speaker for casual listening the last few weeks! Everyone that has heard them has fallen love with them, so I'll be very interested to hear how they hold up at Indiy. The bass is shockingly powerful for 3 1/2 inch diaphragm, they put out comparable bass to many 10 inch sub offers that I've heard and built in the past, they will easily trounce most 8" on the market.
This is the first time I've used a "full range" driver and I'm very pleased with it, working with the top and was challenging but once I got it rolled off and minimized the break up it really smoothed out and is quite surprising how much crisp clear treble this driver can produce. Imaging is excellent, they sound great near field as well as 6 to 8 feet away, they have no trouble filling a room with sound and I have even fooled a couple people into thinking they were hearing the Rally Sports when in fact it was the microfarads.
Most notable, ironically, is their bass performance. In fact they have too much bass, due to the limited excursion capabilities of the passive radiators as well as the very small air volume, tuning frequency is high and the bass response quite boosted below 120Hz. Though they rolloff below 45 Hz, that's enough to encompass the majority of all content in just about all my reference music and other music that I enjoy listening to regularly.
This has been an eye-opening venture into the micro speaker category, and I'm looking forward to doing some more small builds in the future, and another version of these with slightly more airspace with a more capable passive radiator.
Thanks please let me know your thoughts and if you have any questions!
Javad
Project Description:
This is the most challenging smallest speaker I've built to date. Due to the strict enclosure volume restrictions, this is also the most precisely built speaker I've made with each cut toleranced to less than 1/32".
Total internal volume (not air space) is 3 liters including the PS95 sub-enclosure, I was pretty frustrated about some of the nonsensical restrictions on this project initially but ultimately grew to appreciate Ben's sense of neurotic restricted creativity =)
The subwoofer is the Tang Band W5-2053 with 2 Peerless 5.25" per enclosure.
Crossover frequency is about 300hz
Design Goals:
1 - Build a full range speaker capable of solid bass with smooth response to 20kHz
2 - Total internal volume of 3 liters including mid enclosure
3 - Unique striking look
4 - Ensure every possible square inch is covered by a sound radiating diaphragm =)
Driver Selection:
I tried a few different drivers but always knew I'd end up with the W5-2053, this thing is a monster and the bass it puts out from only 3l is astounding. Was an interesting driver to work with as it's response falls off a literal cliff at around 1kHz, so I used that to my advantage in the XO.
I had a pair of PS95's I'd been wanting to try out and was shocked by how good they sounded, so after trying some different drivers I settled on those. They were also welcome with the limited space I had to work with.
Enclosure design:
This was purely determined by 2 factors...driver and PR mounting dimensions and the strict internal volume requirement. As you can see it's all a tight fit.
Precise calculations were made initially using some triangle area calculators to ensure internal volume was at or less than 3l.
Passive Radiators ended up with no weight which resulted in a 56hz tuning frequency, more boosted than I wanted but adding any weight maxed out the excursion that much sooner. I was able to add 15 grams to bring it down to 50 but the passives were straining much sooner, as is the W5 easily over powers 2 5" PR's, really 3 or 4 of these would better keep up with 1 W5.
Another passive radiator issue I dealt with early on was "enclosure walk", using dual opposed passive radiators solves most of that. Also Sorbothane feet in 30 durometer further eliminated any chance of movement.
Enclosure Construction:
Construction is solid mahogany, angled joints are mitered, all glue construction.
I made this CAD (Cardboard Accurate Dimension) to help with the initial concept, I also used it to check test cuts to ensure things were aligning and helping with angle calculations:
Plywood test cut that was perfect, this locked in all my angles on the table saw:
Tape held it all together:
In Mahogany:
I made the cut out of one board to match the grain:
Attaching front baffle:
My cut list:
Test fit:
Clamping and gluing the baffle:
Before I attached the sides I wanted to finalize the mid enclosure, since the PS95 needed no airspace to play to 300hz, I molded a tight fitting fiberglass enclosure.
I started by mounting the driver into a board just like I would in the final enclosure, then I built a makeshift mold using layers of alum foil and masking tape:
Fiberglass matte:
Polyester resin:
Wala, about 5 layers:
Removed from the mold:
Trimmed up and painted:
Built into the mold was a 3/16" Sorbothane disc which creates a CLD treatment to the back of the enclosure, as the driver is screwed down it loads up on this viscoelastic dampening medium and greatly acoustically dampens the mid enclosure. I tested this and it works well:
Mounted, it is attached with silicone adhesive and some screws for good measure:
Time for some sides:
All panels glued and flush, ready for some roundovers:
I didn't have enough room for a full 1" round over like I wanted to do, but fortunately the W5 wouldn't benefit from it, so I developed a way to do a tapered round over using a wedge for the router bearing to ride on:
This created a precise contour that cleared all driver frames.
And all round overs and treatments done:
And a coat of Danish Oil, BOOM! There's the grain!
And after soaking in:
Crossover Design:
I tried many designs including various frequencies and electrical slopes before finalizing on what I have here. I ended up with 18db on the mid and 12 on the sub. Since I was crossing over at 300hz I used an Lpad to not only balance out the more efficient PS95 but also as a baffle step function.
The PS95 also displays break up bad above 15k but it starts around 9k, I implemented a 12db low pass sound 10kHZ which rolled off the top end nicely until it was voiced the way I wanted. Not sibilant but with air and space. Indicators are 18ga, all capacitors are electrolytic except for poly in the PS95 top end roll off and the 1uf listed in the schematic.
I tuned this until it had a flat response but like that the highs just fell flat, despite loving the FR plot it just didn't sound rift, so what sounded best is what's below (near field at about 12" centered on the mid.
Installed, tight fit!
Conclusion:
These were a blast and they've been my go to speaker for casual listening the last few weeks! Everyone that has heard them has fallen love with them, so I'll be very interested to hear how they hold up at Indiy. The bass is shockingly powerful for 3 1/2 inch diaphragm, they put out comparable bass to many 10 inch sub offers that I've heard and built in the past, they will easily trounce most 8" on the market.
This is the first time I've used a "full range" driver and I'm very pleased with it, working with the top and was challenging but once I got it rolled off and minimized the break up it really smoothed out and is quite surprising how much crisp clear treble this driver can produce. Imaging is excellent, they sound great near field as well as 6 to 8 feet away, they have no trouble filling a room with sound and I have even fooled a couple people into thinking they were hearing the Rally Sports when in fact it was the microfarads.
Most notable, ironically, is their bass performance. In fact they have too much bass, due to the limited excursion capabilities of the passive radiators as well as the very small air volume, tuning frequency is high and the bass response quite boosted below 120Hz. Though they rolloff below 45 Hz, that's enough to encompass the majority of all content in just about all my reference music and other music that I enjoy listening to regularly.
This has been an eye-opening venture into the micro speaker category, and I'm looking forward to doing some more small builds in the future, and another version of these with slightly more airspace with a more capable passive radiator.
Thanks please let me know your thoughts and if you have any questions!
Javad
Needed: Bell 7007 / Fostex 800 ?? schematic/service manual
- By Jan Dupont
- Solid State
- 5 Replies
Got my hands on a Bell 7007 Power Amplifier (should have been build for Bell by Fostex and be the same as a Fostex 800 Power Amplifier), and It needs a complete overhaul.
Can't find either the schematics or the service manual though....
Any kind soul here that has it it would like to share with me??
Thanks in advance.
Can't find either the schematics or the service manual though....
Any kind soul here that has it it would like to share with me??
Thanks in advance.
I´ve built a 3A5 preamp
- By Ryssen
- Tubes / Valves
- 110 Replies
I´ve built a 3A5 preamp:
But what I do not completly understand is the Gyrator.
If I set the voltge (Anode) to about 100v,the current through the tube halves is 10mA 20mA per tube,maybe a little high.
And if I set the current to 5mA /triode ,10ma per tube.The voltage is about 60-65 v at anode.
The question is how do I set it?
By the way This one is microphonic....
But what I do not completly understand is the Gyrator.
If I set the voltge (Anode) to about 100v,the current through the tube halves is 10mA 20mA per tube,maybe a little high.
And if I set the current to 5mA /triode ,10ma per tube.The voltage is about 60-65 v at anode.
The question is how do I set it?
By the way This one is microphonic....
What crossover is it?
Can you tell from the pics what kind of crossover it is? What are the frequencies?
For Sale Rode NT-4 Mic For Sale
RØDE NT4 stereo microphone Kit with case.
The RODE NT4 is a single-point X/Y stereo condenser microphone with low-noise electronics and a crisp, detailed sound.
Used in excellent + shape.
Price $ 300.00USD plus shipping( SOLD )
The RODE NT4 is a single-point X/Y stereo condenser microphone with low-noise electronics and a crisp, detailed sound.
Used in excellent + shape.
Price $ 300.00USD plus shipping( SOLD )
Help needed by building a subwoofer filter and looking for a possibility of a sharing Design for testing
- By Micha2007
- Analog Line Level
- 17 Replies
Hello members, 
actually I work on my first LM3886 Amp and for this I want to have also a subwoofer filter.
So I have later a 2.1 System.
I found this and I be very interessed on it:
https://www.lcaudio.dk/pdfs/subfilter.pdf
Does anybody build and make this in this way by EasyEda or KiCad an want to share
the PCB Gerber Data with a young electronic interessted girl ? 😉
I want to test it, and it was on first step easier to get a finished PCB
for testing and understanding.
kind regards
actually I work on my first LM3886 Amp and for this I want to have also a subwoofer filter.
So I have later a 2.1 System.
I found this and I be very interessed on it:
https://www.lcaudio.dk/pdfs/subfilter.pdf
Does anybody build and make this in this way by EasyEda or KiCad an want to share
the PCB Gerber Data with a young electronic interessted girl ? 😉
I want to test it, and it was on first step easier to get a finished PCB
for testing and understanding.
kind regards
2022 Yukon Denali Bose subwoofer dump
- By JOHNNYFAMOUS
- Car Audio
- 2 Replies
Hey all,
I ordered a Yukon Denali 5 months ago and it just now arrived - Micro chip shortage. . I am speechless its an amazing truck!
it has a 14 speaker bose system, As I was expecting the bose subwoofer is not even in the ballpark. the rest sound ok, I can hear the speakers fighting to create bass and they just can't. I have a fair bit of experience building and wiring some high-end car audio systems back in the 90s and lots of current experience with audiophile home systems. I know things have changed since the 90s🙂
Originally I was thinking I would find a place to do a simple sub install, but the more I ask around, the less I trust anyone to work on this thing, they just don't seem to know what they are talking about or are familiar with with these new trucks. I found the Bose sub in the back left quarter panel, and I was surprised to see the fuse box right next to it, got me excited thinking that I could mount AND wire the amp right there off of the fuse box, or close by anyway. Thoughts? I have no idea what AWG wire is there but assume I would want at least 8awg. I had visions of having to run a power supply all the way to the battery. I suppose that is still probably ideal but I would prefer not to if I can help it, it sure is a far distance. Also, it appears I can just get an amp with high-level inputs and unplug the bose right there?
I plan to run a small 200-400 watt RMS amp and then build a small ported enclosure for a 10 or 12-inch subwoofer. There really is not much room with the 3rd row up.
Any thoughts or experience with the wiring back there on a 21 or 22 yukon??
I ordered a Yukon Denali 5 months ago and it just now arrived - Micro chip shortage. . I am speechless its an amazing truck!
it has a 14 speaker bose system, As I was expecting the bose subwoofer is not even in the ballpark. the rest sound ok, I can hear the speakers fighting to create bass and they just can't. I have a fair bit of experience building and wiring some high-end car audio systems back in the 90s and lots of current experience with audiophile home systems. I know things have changed since the 90s🙂
Originally I was thinking I would find a place to do a simple sub install, but the more I ask around, the less I trust anyone to work on this thing, they just don't seem to know what they are talking about or are familiar with with these new trucks. I found the Bose sub in the back left quarter panel, and I was surprised to see the fuse box right next to it, got me excited thinking that I could mount AND wire the amp right there off of the fuse box, or close by anyway. Thoughts? I have no idea what AWG wire is there but assume I would want at least 8awg. I had visions of having to run a power supply all the way to the battery. I suppose that is still probably ideal but I would prefer not to if I can help it, it sure is a far distance. Also, it appears I can just get an amp with high-level inputs and unplug the bose right there?
I plan to run a small 200-400 watt RMS amp and then build a small ported enclosure for a 10 or 12-inch subwoofer. There really is not much room with the 3rd row up.
Any thoughts or experience with the wiring back there on a 21 or 22 yukon??
europower ep2000
- By karachay
- Solid State
- 2 Replies
hi friends. i try to repair my amplifier but i stuck on silly error. on d5 and d8 i cannot get 15v. i change zeners but still same problem. any idea why i cannot get 15v from them?
it was burn power transistors 5200 and 1943. i change them and test it and see that 15v not coming. i check driver transistors too they are ok.
thank you for all answers.
it was burn power transistors 5200 and 1943. i change them and test it and see that 15v not coming. i check driver transistors too they are ok.
thank you for all answers.
unusual failure mode for a speaker driver (at least for me)
- By jussik
- The Lounge
- 9 Replies
