I glad you realize this safety issue. For your info, there are similar thread in this forum that already closed by Moderator.
Yes, this Bob Carver and Sunfire is the name I remember seeing in the High End magazine. Except that I saw it in connection with a tower speaker. I remember it as a 500 watt amp in the subwoofer section of the tower. This would supplement your external amp. You external amp would power the upper drivers.
Carver says it is about the size of a candy bar. That was what made me see it as having to be unisolated, not even having a switching supply.
This cube subwoofer has a special driver, with lots and lots of displacement.
This small box approach is one subsituting raw power for box volume. It is probably as case of running below fs too?
This special driver might have been designed to meet the requirements of power mains isolation. It would be tough.
I am continuing to read from this site.
It was, I believe, this Bob Carver and Sunfire that inspired me to start this thread.
This is an outstanding forum.
I have reservations about transformerless systems.
Here it seems to be part of a raw power approach to low bass. See my below fs thread.
Kartino, can we still read that closed thread?
I don't want to advocate anything unsafe.
It was because I was alarmed at the thought of transformerlessness that I took not of the Bob Carver Sunfire ad.
In fact, what I saw was not being offered by Bob Carver.
It was offered by some other make. But they advertised that the special little amp board was designed by Bob Carver, and was of the Sunfire type.
Was their driver built to provide isolation?
There are many questions here, and I think this is the right group to explore them with.
Carver says it is about the size of a candy bar. That was what made me see it as having to be unisolated, not even having a switching supply.
This cube subwoofer has a special driver, with lots and lots of displacement.
This small box approach is one subsituting raw power for box volume. It is probably as case of running below fs too?
This special driver might have been designed to meet the requirements of power mains isolation. It would be tough.
I am continuing to read from this site.
It was, I believe, this Bob Carver and Sunfire that inspired me to start this thread.
This is an outstanding forum.
I have reservations about transformerless systems.
Here it seems to be part of a raw power approach to low bass. See my below fs thread.
Kartino, can we still read that closed thread?
I don't want to advocate anything unsafe.
It was because I was alarmed at the thought of transformerlessness that I took not of the Bob Carver Sunfire ad.
In fact, what I saw was not being offered by Bob Carver.
It was offered by some other make. But they advertised that the special little amp board was designed by Bob Carver, and was of the Sunfire type.
Was their driver built to provide isolation?
There are many questions here, and I think this is the right group to explore them with.
Still reading from the Bob Carver site.
Definitely, this is a note worthy design.
This certainly involves a kind of driver I wouldn't expect to find at radio shack.
Definitely, this is a note worthy design.
This certainly involves a kind of driver I wouldn't expect to find at radio shack.
Bob Carver thinks the use of MOSFETs for Amp output is just a fad!
Yes!
This Carver web site is absolutely fascinating, and could be the subject of intense study.
I do not see it anywhere say the built in amps are transformerless. But I think is is probable.
Look at his special drivers. They don't really have a cone, rather it is a flat disk.
So, if there is such a thing as a safe transformerless amp and powered speaker, I think these are it!
Now, the other Sunfire products would not be transformerless.
Highly intriquing.
But also, I am not going to buy a driver and duplicate this. Some audio stuff yes, but not this.
Carver is one of those handful of names that influence where everything else goes.
Yes!
This Carver web site is absolutely fascinating, and could be the subject of intense study.
I do not see it anywhere say the built in amps are transformerless. But I think is is probable.
Look at his special drivers. They don't really have a cone, rather it is a flat disk.
So, if there is such a thing as a safe transformerless amp and powered speaker, I think these are it!
Now, the other Sunfire products would not be transformerless.
Highly intriquing.
But also, I am not going to buy a driver and duplicate this. Some audio stuff yes, but not this.
Carver is one of those handful of names that influence where everything else goes.
I think Velodyne is the one manufacturing transformerless subwoofers. For last 10 years at least.
You would need at least:
1. Cone with Reinforced insulation, possibly plastic woofer frame
2. Line-input isolation transformer (UL approved, 4kV insulation rating etc. NOT normal line-in isolation tranny)
3. Amp and speaker in same case
4. All metal parts(magnets etc) grounded etc
You would need at least:
1. Cone with Reinforced insulation, possibly plastic woofer frame
2. Line-input isolation transformer (UL approved, 4kV insulation rating etc. NOT normal line-in isolation tranny)
3. Amp and speaker in same case
4. All metal parts(magnets etc) grounded etc
zenmasterbrian said:
Concerning that thread, bipolar transistors are only worth the effort when voltages over 300V have to be blocked, while MOSFET always produces better performance below 300V.
Try to find a TO-220 MOS device under $1 capable of switching 10A with 1V voltage drop and blocking 700V.
Then check the good old MJE13009 (my favourite switching bipolar). Four of these properly driven can produce in excess of 1800W continuous output with little losses in a transformer-coupled regulated SMPS.
Also, note that MOSFET become plain junk when it comes to switch anything above 600V, which is where bipolar and IGBT devices really excel. Note that high voltage MOSFETs show very high conduction losses, and also suffer from slow turn-on and tail currents due to high gate spreading resistances. Some low voltage low-tech MOSFET devices also suffer from tail currents.
Finally, the following document explains why conventional MOSFET devices explode instantaneously if I try them in my 350V 30A class D amplifier. They become nice thyristors for a few microseconds just after their clumsy body diode has been conducting 😀😀😀
http://www.irf.com/technical-info/whitepaper/s30p5.pdf#search="mosfet body diode dv/dt failure"
BTW: Forget about clumsy and outdated APT stuff and check the new CoolMos series from Infineon (and their body diodes). APT seems almost dead now.
Eva said:
But bipolars have always lower voltage drop than mosfet
But bipolars have always lower voltage drop than mosfet
But bipolars have always lower voltage drop than mosfet
But bipolars have always lower voltage drop than mosfet...
😀
Thanks EVA,
And while we're at it why are things like IGBTs and GTOs still around? IGBTs are just bipolars wearing FET's clothes.
🙂
And while we're at it why are things like IGBTs and GTOs still around? IGBTs are just bipolars wearing FET's clothes.
🙂
Not too long ago, I had the privilege of working with an Electronics Engineer from China. He was absolutely brilliant and had vast amounts of experience from all over the world in areas including military RF, test equipment, power supply design, computer monitor design, and more.
While working on a power supply design problem, he laughed and mentioned that about 90% of the switching AC adapters he’d seen coming from China had not passed CE or UL inspections, yet had CE, UL, FCC, VCCI, and others marked on them. He said that most were “pretty” safe and most might even pass agency inspections if tested, but because of the poor business accountability in China, they had no worries about deaths or accidents.
I found this disturbing and always question the safety of everything. I have also questioned the safety of many other AC power products produced in China including high-end audio products, powered speakers, and others. I always recommend using caution when purchasing cheap or too-much-performance-for-the-cost products, and especially ones from Asian countries, although that’s virtually impossible to avoid. I wouldn’t put too much faith into UL and CE stamps either. Stick with name-brand products and those from established manufacturers.
When building your own power projects, always be very careful and do plenty of research before plugging in.
While working on a power supply design problem, he laughed and mentioned that about 90% of the switching AC adapters he’d seen coming from China had not passed CE or UL inspections, yet had CE, UL, FCC, VCCI, and others marked on them. He said that most were “pretty” safe and most might even pass agency inspections if tested, but because of the poor business accountability in China, they had no worries about deaths or accidents.
I found this disturbing and always question the safety of everything. I have also questioned the safety of many other AC power products produced in China including high-end audio products, powered speakers, and others. I always recommend using caution when purchasing cheap or too-much-performance-for-the-cost products, and especially ones from Asian countries, although that’s virtually impossible to avoid. I wouldn’t put too much faith into UL and CE stamps either. Stick with name-brand products and those from established manufacturers.
When building your own power projects, always be very careful and do plenty of research before plugging in.
Hi All,
I am very familiar with the Carver tracking down-converter. These supplies are isolated from the AC mains by a conventional transformer. The secondary is rectified and filtered in the conventional way. The output is Pulse Width Modulated basically, to allow the desired amount of energy through to your circuits. This is done at a high frequency to make additional filtering easier.
Nothing magical, and it works very well. In the Lightstar (original) the supply sits around 12 ~ 13 VDC above and below ground. I owned one of these amps for a while. One of the best for sound in the Carver line. The other point is that the raw supplies would sit at + / - 125 VDC. Each channel had it's own supply, two power cords.
I still kind of miss it.
But it was not directly connected to the AC mains from the secondary side!
My advice is very simple. Do not construct any device that runs directly from the AC mains with no isolation. In other words, use a transformer, or don't build it!
-Chris
I am very familiar with the Carver tracking down-converter. These supplies are isolated from the AC mains by a conventional transformer. The secondary is rectified and filtered in the conventional way. The output is Pulse Width Modulated basically, to allow the desired amount of energy through to your circuits. This is done at a high frequency to make additional filtering easier.
Nothing magical, and it works very well. In the Lightstar (original) the supply sits around 12 ~ 13 VDC above and below ground. I owned one of these amps for a while. One of the best for sound in the Carver line. The other point is that the raw supplies would sit at + / - 125 VDC. Each channel had it's own supply, two power cords.
I still kind of miss it.
But it was not directly connected to the AC mains from the secondary side!
My advice is very simple. Do not construct any device that runs directly from the AC mains with no isolation. In other words, use a transformer, or don't build it!
-Chris
Maybe you had an external Sunfire amp?
In the ad I saw, it was just a little tiny circuit board.
In this paper in says it is the size of a large candy bar.
Maybe they have specially designed the driver to make it provide reliable isolation.
I don't know, and it does concern me. That is why I started this thread.
In the ad I saw, it was just a little tiny circuit board.
In this paper in says it is the size of a large candy bar.
Maybe they have specially designed the driver to make it provide reliable isolation.
I don't know, and it does concern me. That is why I started this thread.
Hi zenmasterbrian,
We would rather not interfere unless things get completely out of control as the other thread appeared it may.
-Chris
Actually, there are many moderators around. We do not always post in a thread either, even though the thread is read. The thread you have referred to had already come up in discussion.
We would rather not interfere unless things get completely out of control as the other thread appeared it may.
-Chris
Hi zenmasterbrian,
I didn't see where it stated there was no power transformer. If they combined a mag coil circuit followed by a down-converter the results may be interesting. A mag coil is smaller and lighter than a standard transformer, but still provides full isolation. They may not have shown the complete power supply and amplifier.
I think a high frequency switcher driving the down-converters might be the answer. This would be very efficient indead. The circuit board you saw was probably just the amplifier circuit. I have not seen the inards of the sub.
-Chris
I didn't see where it stated there was no power transformer. If they combined a mag coil circuit followed by a down-converter the results may be interesting. A mag coil is smaller and lighter than a standard transformer, but still provides full isolation. They may not have shown the complete power supply and amplifier.
I think a high frequency switcher driving the down-converters might be the answer. This would be very efficient indead. The circuit board you saw was probably just the amplifier circuit. I have not seen the inards of the sub.
-Chris
Thanks. How about getting my class D thread going again?
Anyone seen one of these Sunfire Subs? The driver looks like a flat disk, not a concave cone. It looks like it could be deisigned for isolation.
Anyone seen anything else unisolated?
Of course the vacuum tube TVs and radios had loud speakers. But they were more recessed that audiophile speaker enclosures are today. They had a cloth grill, but they also had the plastic enclosue, with narrow slats.
I'm not advocating this. I just want to know what is on the market, and how sane it is.
Anyone seen one of these Sunfire Subs? The driver looks like a flat disk, not a concave cone. It looks like it could be deisigned for isolation.
Anyone seen anything else unisolated?
Of course the vacuum tube TVs and radios had loud speakers. But they were more recessed that audiophile speaker enclosures are today. They had a cloth grill, but they also had the plastic enclosue, with narrow slats.
I'm not advocating this. I just want to know what is on the market, and how sane it is.
Hi zenmasterbrian,
-Chris
In a PM response, I told you that the events in that thread were under consideration at this point. Your comment is not helpful to your cause.
This is not why the driver has a flat surface. You should direct your inquiry directly to Sunfire for a factual response from the guys who designed it.
I have watched people get zapped and been zapped. It is not safe and that is why you don't see it any more.
There is nothing legal on the market that I can think of in the way of consumer audio equipment. For safety reasons, this is not sane in the least! You should have a look at what they got away with in the 20's and 30's. Mind blowing, and there were deaths. Electricity is not a toy and should always be treated with the utmost respect. Fail to do this at your own peril, or the peril of others around you. It is for this reason that this topic may be closed. Even for what appears to be an academic discussion.
-Chris
Hi, Eva and MJJZ,
I gree with Eva, Mosfet are good for under 200V (for me!) and for you MJJZ, at high voltage the Rds on beetween bipolar and mosfet not a concern anymore, remember that this is HIGH VOLTAGE, you know relation in ohms law, that at high voltage a small resistance is no a corcern, but the concern is a small capacitance at high voltage at high speed switching became very trouble. Salute to EVA for her experience!
And I agree to for sub with mains with some rule shall follow as MJJZ said. But I believe that only commercial manufacturer that able to design the special box, special speaker, good input isolation, good ground arrangement etc. But for DIYer still NO-NO!
I gree with Eva, Mosfet are good for under 200V (for me!) and for you MJJZ, at high voltage the Rds on beetween bipolar and mosfet not a concern anymore, remember that this is HIGH VOLTAGE, you know relation in ohms law, that at high voltage a small resistance is no a corcern, but the concern is a small capacitance at high voltage at high speed switching became very trouble. Salute to EVA for her experience!
And I agree to for sub with mains with some rule shall follow as MJJZ said. But I believe that only commercial manufacturer that able to design the special box, special speaker, good input isolation, good ground arrangement etc. But for DIYer still NO-NO!
I agree that mains is not toys.
Somebody who have realize the risk of electricity is somebody who have no knowledge about electricity. Because this is not conversation beetwen students and teacher, but this is talking about our life in reality.
I am very sorry for you Brian, take electrical college first before you talking about electrical safety.
BTW. Are you in college?
Somebody who have realize the risk of electricity is somebody who have no knowledge about electricity. Because this is not conversation beetwen students and teacher, but this is talking about our life in reality.
I am very sorry for you Brian, take electrical college first before you talking about electrical safety.
BTW. Are you in college?
Hello all, I'm really enjoying reading this one.
RE: Sunfire Subs, we have a few dozen at work- both the ruggedized version for pro use and the home version. I can take one apart and post pics if you want.
RE: Sunfire Subs, we have a few dozen at work- both the ruggedized version for pro use and the home version. I can take one apart and post pics if you want.
Hi imix500,
The pictures would be instructional. Thank you for your offer.
I had some Carver subs apart under warranty (long time ago!). They were not remarkable in a Carver sense. Nothing stayed with me as being special. The Lightstar was special.
The pictures may satisfy some curiousity.
-Chris
The pictures would be instructional. Thank you for your offer.
I had some Carver subs apart under warranty (long time ago!). They were not remarkable in a Carver sense. Nothing stayed with me as being special. The Lightstar was special.
The pictures may satisfy some curiousity.
-Chris
- Status
- Not open for further replies.