Krell Issues Recall on Four Amps

[klipschfan]

Krell Issues Recall on Four Amps Home Theater NewsPower Amplifier NewsWritten by AVRev.com Thursday, 23 July 2009





Four amplifiers from Krell have been recalled due to potential overheating problems. The KAV-1500, KAV-500i, KAV-250a/3, and KAV-250a models have been called in for a recall so that Krell can replace faulty fuses that might cause the units to overheat.
Krell will be responsible for the cost of the fuse replacement. Once a certificate of replacement is presented, they will issue a $100 check to whoever did the installation. For any questions, Krell customers are to call Walt Schneider at 203.298.4014 or at service@krellonline.com. This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

[jdandy]

I find this fuse replacement deal, and the reason for it a little unusual. What it sounds like is Krell plans to put lower current rated fuses in the amps. I guess the reasoning is that before the amps can put out enough power to get too hot, they will just blow the fuse. Hmm. It seem more prudent to install large enough heat sinks to cool the amps properly during operation within their advertised ratings. Perhaps when Krell started building these amps in China they cut a few corners in the design, and the smaller fuse is the quick fix. If I were an owner of one of these Krell amps, this fix would not make me happy.

[PHC1]

Originally Posted by jdandy

I find this fuse replacement deal, and the reason for it a little unusual. What it sounds like is Krell plans to put lower current rated fuses in the amps. I guess the reasoning is that before the amps can put out enough power to get too hot, they will just blow the fuse. Hmm. It seem more prudent to install large enough heat sinks to cool the amps properly during operation within their advertised ratings. Perhaps when Krell started building these amps in China they cut a few corners in the design, and the smaller fuse is the quick fix. If I were an owner of one of these Krell amps, this fix would not make me happy.

Or perhaps they just used a fuse with too big of a rating that is not needed to produce full rated power?

[jdandy]

Originally Posted by PHC1

Or perhaps they just used a fuse with too big of a rating that is not needed to produce full rated power?

Serge.......I guess that's where the confusion comes in. How does reducing maximum current capibility of a fuse make an amp run cooler without the fuse blowing? If the amps are still able to produce full rated power with the new fuse, how does this control the operating temperature of the amp?

[PHC1]

Originally Posted by jdandy

Serge.......I guess that's where the confusion comes in. How does reducing maximum current capibility of a fuse make an amp run cooler without the fuse blowing? If the amps are still able to produce full rated power with the new fuse, how does this control the operating temperature of the amp?

I guess that would depend on where and what that fuse controls. I doubt Krell would pay $100 to replace a simple fuse that would be user accessible which leads me to believe it may be an internal fuse.

[jdandy]

Serge.......Internal or external, a fuse is simply an over current device that opens when the rating is exceeded. A fuse is not a current controlling device that manages current flow by reducing it during a period of peak demand. I might have to give Walt Schneider a call just to satisfy my curiosity.

[PHC1]

Krell Industries has issued a recall for four amplifiers: the KAV-250a, KAV-250a/3, KAV-500i and KAV-1500 due to rail fuse ratings. The recall effects models made between January 1997 and February 2001. The amplifiers, which were designed to operate at temperatures warm to the touch, may have fuse values that could cause the units to overheat. Krell says the recall consists of replacing two rail fuses for each amplifier channel and will supply and install the new fuses free of charge or the user can have the change done by a qualified technician. Frankly, this is easy for virtually anyone to do. Krell says a certificate of fuse replacement must be noted upon successful replacement of the fuses. Upon verification, Krell will issue a $100 check to the person responsible for the fuse replacement. End users should contact Walt Schneider at (203) 298-4014 or at service@krellonline.com with any questions about the recall.

[PHC1]

Amplifiers Recalled by Krell Industries Recalled Due to Fire Hazard
The U.S. Consumer Product Safety Commission, in cooperation with the firm named below, today announced a voluntary recall of the following consumer product. Consumers should stop using recalled products immediately unless otherwise instructed.

Name of Product: Amplifiers

Units: About 2,300

Distributor: Krell Industries LLC, of Orange, Conn.

Hazard: The amplifiers were designed to operate at a temperature warm to the touch. However, a component input device can fail and cause the amplifiers to overheat, posing burn and fire hazards to consumers.

Incidents/Injuries: Krell has received 50 reports of the amplifiers overheating including reports of smoke and electrical fire. No injuries have been reported.

Description: This recall involves Krell power amplifiers with model numbers KAV-250a, KAV-250a/3, KAV-500i and KAV-1500. The amplifiers are used to provide power to a loudspeaker in a home audio playback system. The Krell logo is printed on the front of the amplifier.

Sold by: Authorized dealers and distributors of audio equipment nationwide from January 1997 through February 2001 for between $3,000 and $8,000.

Manufactured in: USA

Remedy: Consumers should immediately stop using the amplifiers, and contact Krell to schedule the free installation of replacement fuses.

Consumer Contact: For additional information contact Krell at (888) 436-6055 between 9 a.m. and 4:30 p.m. ET Monday through Friday, or visit the firm's Web site at www.krellonline.com. Consumers can also email the firm at service@krellonline.com .

[PHC1]

Originally Posted by jdandy

Serge.......Internal or external, a fuse is simply an over current device that opens when the rating is exceeded. A fuse is not a current controlling device that manages current flow by reducing it during a period of peak demand. I might have to give Walt Schneider a call just to satisfy my curiosity.

Yes Dan, technically you are correct. What I am thinking though is if there is an internal fuse, which in this case there are actually two, one for each "rail", if the fuse is of the wrong size, it can can continue to provide current to the transistors in whatever stage that would cause them to exceed the safety operating range and overheat.

When stereophile tested the Ayre MX-R, there was a situation where one needed to change the rail fuse from 10 to 15 amps to test the amplifiers into 2 ohm loads at full power. The extra current ability of the larger rail fuse was needed to get there. The undersized fuse blew too soon. Krell may have put a fuse that was too large and not blow soon enough to prevent thermal runaway.

[jdandy]

Serge.......That makes sense, and when I think about it this is probably what is happening. I'll recend my China quip.