That was one that immediately sprung to mind, but there are various other self immolating designs out there.
I might also include things like the audible illusions preamps that ran the tubes way too hard for a decent life.
Grey area comes with amps that die if turned on with no speakers connected
. unconditionally stable seems optional in high end products...
I might also include things like the audible illusions preamps that ran the tubes way too hard for a decent life.
Grey area comes with amps that die if turned on with no speakers connected
. unconditionally stable seems optional in high end products...
I fixed one of those for an acquaintance when I lived in Taiwan.
Idiosyncratic and as hot as hell probably best describes it, but it did sound wonderful.
I believe around 1980 Counterpoint had a preamp with some thermal problems. It shut down after about an hr. But if the cover was off you could blow, not with a fan but just blow with your mouth from about 2 feet on the Lm7812 and it would turn back on for a while. I mentioned to one of the engineers that they were dissipating about 8 W from that part and they responded something like " that's no problem it's a 20w part " I didn't point out that that 20w rating was on a perfect heatsink not a small one mounted about 1" from a vacuum tube or they didn't need to supply that 12v regulator with 20V . So how did they solve this problem ? easy find some off brand 7812's that didn't have a thermal cutoff built in.
Add dangerous to that. It nearly cost me an eye when I tested one and it exploded. Also not enough clearance between mains voltage carrying parts and PCB etc. The silly volume control, the volume potentiometer becoming unreliable because of the heat...
For some reason the designers name was published and it helped people defending the product despite all the drawbacks that would normally not have been accepted. That's how it works. Design a turd amplifier, add no speaker protection, put a famous name on it and when it burns the woofers its fans/zealots will say it was your own fault
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I don't disagree - many of the rules broken and that volume control :O
In the one that I repaired, there were some power resistors in series with IIRC a second set of reservoir caps that had burnt out. After fixing it I just took a listen before returning it and it sounded very smooth - that's what lead to the sx-Amp, but a totally different design from my side of course.
In the one that I repaired, there were some power resistors in series with IIRC a second set of reservoir caps that had burnt out. After fixing it I just took a listen before returning it and it sounded very smooth - that's what lead to the sx-Amp, but a totally different design from my side of course.
That's not much of an engineering staff. 20W part
I'm way more careful than that.This is so easy to solve. A series power resistor can dissipate half of the wasted power. Plus it doubles as a fuse
.
It depends on how they worked out the fan size.
Maybe it was just thrown in.
Or maybe it was worked out.
Or maybe they tried it and it worked ok ?
I have a Marshall 100 watt guitar amp that is a TDA chip amp with same size fan.
The big mistake was to have the fan blow air in but no output vent !
The case is far from leaky.
The in vent seems to be the out vent too.
Maybe it was just thrown in.
Or maybe it was worked out.
Or maybe they tried it and it worked ok ?
I have a Marshall 100 watt guitar amp that is a TDA chip amp with same size fan.
The big mistake was to have the fan blow air in but no output vent !
The case is far from leaky.
The in vent seems to be the out vent too.
List is sooo long. Just a few:
I had a C&M labs power amp that was unstable. Blew up three times.
Replaced it with a Sanyo MOSFET. Good sounding, except the Freon in the heat pipe gurgled loud enough to hear it in quiet passages. Replaced it with a B&K. Much better but their physical ground structure was not good. They did fix it in later builds.
Anyone one puts a freaking fan in a unit designed to be in the living spaces is just plain stupid.
Looked at a Krell preamp once. Grey paint on a silver box. You had to get a flashlight to read the controls. No one old enough to afford it could use it.
Early Deon AVR's tuner controls were virtually unusable
Not fond of the tiny buttons on my OPPO BD. Can't see them, can barely feel them.
Slot loading CDs. All of them.
OK, going to insult someone here, but an SP-12 was a bad design as it was too blankety blank hard to get set up right. SOTA had them beat hands down.
Push buttons on the first Hafler preamps did not last a year.
I still thing any remote with toggle codes is stupid. When first invented, OK as we had limitations, but not now. It makes remotes get out of sync. What good is a remote if I have toget up and go over to see what did not stert correctlly?
I had a C&M labs power amp that was unstable. Blew up three times.
Replaced it with a Sanyo MOSFET. Good sounding, except the Freon in the heat pipe gurgled loud enough to hear it in quiet passages. Replaced it with a B&K. Much better but their physical ground structure was not good. They did fix it in later builds.
Anyone one puts a freaking fan in a unit designed to be in the living spaces is just plain stupid.
Looked at a Krell preamp once. Grey paint on a silver box. You had to get a flashlight to read the controls. No one old enough to afford it could use it.
Early Deon AVR's tuner controls were virtually unusable
Not fond of the tiny buttons on my OPPO BD. Can't see them, can barely feel them.
Slot loading CDs. All of them.
OK, going to insult someone here, but an SP-12 was a bad design as it was too blankety blank hard to get set up right. SOTA had them beat hands down.
Push buttons on the first Hafler preamps did not last a year.
I still thing any remote with toggle codes is stupid. When first invented, OK as we had limitations, but not now. It makes remotes get out of sync. What good is a remote if I have toget up and go over to see what did not stert correctlly?
That's not much of an engineering staff. 20W part
This is so easy to solve. A series power resistor can dissipate half of the wasted power. Plus it doubles as a fuse
Solving a design error with a new design error
Normally one would choose a lower secondary voltage on the transformer. Why generate useless heat?
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The mains is always 220V assumption (250V for me) and not understanding transformer regulation
I don't know if the design can be considered a huge engineering error and it would have to be redesigned, that would lead to a much larger volume of rendering it impractical.
There is a lot of space inside from what is seen in the photos of the OT and that I have been able to find on the web, if the cover of the AR VT200 allows a good flow of air upwards, it should be fine.
I haven't read anything about the fan being noisy in the reviews in the attached link, aren't the bearings worn and do you need a replacement?
A Noctua NF-A8 PWM moves 55.5 M3 / H, I recently replaced the original fan of a 1000 Watts (bridge) PA, class D, for that model and the result is excellent for home use. Totally silent But it is 80mm, maybe a 40mm one is an easier replacement, although the NF-A4x20 PWM moves 9.4 m³ / h ...
Noctua
Audio Research VT200 Amplifiers user reviews : 5 out of 5 - 12 reviews - audioreview.com
There is a lot of space inside from what is seen in the photos of the OT and that I have been able to find on the web, if the cover of the AR VT200 allows a good flow of air upwards, it should be fine.
I haven't read anything about the fan being noisy in the reviews in the attached link, aren't the bearings worn and do you need a replacement?
A Noctua NF-A8 PWM moves 55.5 M3 / H, I recently replaced the original fan of a 1000 Watts (bridge) PA, class D, for that model and the result is excellent for home use. Totally silent But it is 80mm, maybe a 40mm one is an easier replacement, although the NF-A4x20 PWM moves 9.4 m³ / h ...
Noctua
Audio Research VT200 Amplifiers user reviews : 5 out of 5 - 12 reviews - audioreview.com
You are probably right. Though lots of tube produces heat; a different angle picture shows just enough verticle space. An advertisement on net as follows
Audio Research VT200 200W/ch Stereo Tube Power Amplifer Dealer Ad - US Audio Mart
suggests this amplifier is/was 20 year old and original tubes were still working. Which the seller is selling along with new tubes. We can say that tube and amplifier survived the heat. The design could have been better but they did just about alright considering amplifier size would have been one minor criteria in typical home use where one can place it along with other equipments.
Regards
Solving a design error with a new design error
It depends on what voltages you have available. When it comes to transformers, I use what I have for the most part. (I have a whole lot of salvage transformers.) And for a manufacturer, they use parts that they can order in quantity for a discount.
I don't see how it's an error if it works and provides long life.
It certainly doesn't compromise the sound. It's cheaper than having a custom transformer made or using two transformers. I have a stash of power resistors just for this application. 
It does for me. If I'm spending money to get high-quality audio I don't want to be paying for the opposite: fan noise.
This is the kind of design error that is big, in one regard, because it's likely to be "justified" with rationalizations.
The only scenario I can think of where the fan noise (that is obtrusive enough to be noticed in the listening room) isn't an issue is if the amp is placed in another room and the cables are put through the wall to the other. That's a solution for PCs with their "inaudible" fans, too.
That solution also has the benefit of putting the heat from the amp into a different space where it noise from the air conditioning to compensate for the heat buildup might be less onerous (such as if that other room is much larger than the listening room).
If people like the Stereophile reviewer had said the fan is truly inaudible at normal distance without adjusting its speed control then it would not be as big of a flaw. It's still problematic, though, for pulling in dirt and for other reasons.
People citing long life for the amp are using the apples and oranges fallacy. Apples = fan noise (design sound quality). Oranges = long life (design reliability).
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A serious manufacturer uses the right transformer and limits generation of useless heat to a minimum and gets reliability in return (and so does the buyer).
Salvaging transformers in the DIY field often leads to using the wrong voltage resulting in having to resort to tricks. It is more efficient and elegant to design with the right values not to use what one has.
Salvaging transformers in the DIY field often leads to using the wrong voltage resulting in having to resort to tricks. It is more efficient and elegant to design with the right values not to use what one has.
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