Having guarantee issues with KR Audio?

After speaking with Eunice Kron( owner of KR) over dinner in Las Vegas, she advised that KR no longer has any intention of selling KR 300Bs to any outside source, instead opting to manufacture tubes solely for use in their own amplifiers. However, right after this conversation, she doubled the price of the 300B tubes over night.

As for reliability and warranty of KR 300Bs, their longevity for those tubes manufactured in the last 18 months has deteriorated. They seem to be more prone to premature demise. Coincident has received back about a half dozen 300Bs that have gone bad within 6 months of use. KR does offer a 6 month warranty. Well this is not really a warranty at all, as it turns out. After sending back to KR all the defective 300Bs, KR denied offering replacements because " the tubes were misused by their owners and therefore not subject to the warranty". In other words, KR offers a warranty but if a tube becomes defective it is the user's fault and not KR's.

In the case of 2 customers who had their KR 300B balloons expire within 2 months of use, we replaced them free of charge inspite of the fact that we only offer a 14 day warranty on tubes.

Due to all of the above, we no longer stock nor sell KR 300Bs. Our standard supplied EH Gold Grids have proven to be extremely reliable( not a single failure in the field) and sound superb. For those who wish to upgrade, we highly recommend the Sophia or TJ carbon plates. They sound great and their manufacturers extend a genuine up to one year replacement warranty. We no longer offer for sale, any 300Bs other than the EHs since we are confident in their reliability and sonic performance.

As for using differing 300B tubes in the Frankenstein amplifiers, all of them will work as the operating voltages and bias current of our amps is within spec for all of them. Stereomojo used the Frankenstein as the reference amplifiers in a 6 tube 300B comparison with no tube failures. If the 300B is properly manufactured and falls within the specs required for a 300B, it will work without incident in the Frankenstein amplifiers. Some tubes are better constructed then others and will last longer but that is a tube issue nothing to do with the amplifiers.

Israel Blume
Coincident Speaker Technology

All the KR 300Bs Coincident received were purchased directly from Eunice Kron in her capacity as owner of KR. From the time or order and prepayment, which was demanded, delivery would take a minimum of 60 days and at times, 120 days. Mrs. Kron stated that all our orders had to be manufactured , therefore the delay. At no time was there any mention that the tubes were anything but current manufacture and up to the latest spec. Coincident ordered and received KR 300Bs on at least four occasions spanning a two year period. On one occasion, delivery after prepayment of the order took 6 months to be delivered.

I took this issue and the reliability problems up with Mrs. Kron when we had dinner at CES 2009. During our meeting she admitted to delays in deliveries and quality control problems which she attributed to the turnover in staff from the very experienced previous workers to new employees who had little or no tube manufacturing expertise. She also admitted to serious financial difficulties and offered to sell the tube manufacturing business to me.

The reliability problems were not solved during the entire time Coincident purchased KR tubes. Mrs. Kron, when sent the defective 300Bs simply refused to replace them or offer a refund, rather stating," if they failed, the tubes must have been used incorrectly". In other words, we offer a warranty, unless the tubes fail.

Coincident has since switched to recommending the Black Bottle Treasury 300Bs, which have in over two years of use in the field , not suffered a single failure and they sound superb.

Israel Blume- Pres.
Coincident Speaker Technology