Bentley Acoustic Corporation EC86 Tubes
 

I recently purchased, but have not yet received, a used Acoustic Plan Digimaster DAC. It has four EC86 tubes which are imprinted with the name "Bentley Acoustic Corporation". Can anyone tell me something about these tubes - ?sound quality as compared with other EC86 tubes, value, availability, manufacturer(s)...?

Thank You

Canudos.......Bentley Acoustic Corporation was not a tube manufacturer. They were an import reseller based in England. They are no longer in business. From what I have found, Bentley Acoustic Corporation purchased surplus tubes and had them branded with their logo. Your guess is as good as anyone's on where the tubes were manufactured.

Just heard back from Acoustic Plan, I can use EC86, E86C or EC806S tubes from any source. They confirmed that BAC tubes would no longer be available. They also said that it is important that the tubes be "matched to a quartet".

Do you know or can you suggest a source that will describe the expected sound differences among the three tube choices?

Can you elaborate on the "matched to a quartet" statement? I know that there are several different measurements for tubes but I do not know which ones are the most important or how close a match each tube needs to be in relation to the other three to be considered a good match?

Canudos.......It is rare that a tube seller will express the sound of a particular tube other than a very generalized comment. This is because the tube is only part of an audio circuit and the final result of the sound is dependent on the entire circuit design, not just the tube. This is why tube aficionados who routinely swap tubes in their amplifiers often have many different versions from different manufacturers of the same tube. The only way to truly understand the sound of different tubes is to use them in your amplifier.

Matching triode tubes is done by comparing a tubes transconductance, gain, and plate current to other tubes. When tubes display close electrical properties with other tubes they are considered a matched pair or matched quad, etc. Most tube venders charge an additional fee to match tubes. If it is important to you, be certain your tube vendor will provide that service and provide the electrical data on the tube box. It is very rare to see triode tubes that are a true perfect match, but being close is generally satisfactory.

EC86 tubes can still be found from Mullard, Philips, and others, usually costing $15 to $30 each. The EC806S is a Telefunken tube and can be a bit more difficult to locate. Do a Google search for tube sellers of these tube types.

Thanks, I appreciate your guidance. Since these are inexpensive tubes, actual trials are feasible.