Any experience with EZ-80s, 5687s or Bendix 6900s?


I have an AMR CDP and it uses EZ-80s as rectifiers and 5687s in the output stage. I may have a problem with a rectifier tube and was thinking of replacing it (them). I know nothing about EZ-80s (or EZ-81s). The current rectifier is an NOS Philips. Does anyone here know what a Telefunken EZ-80 might sound like in this application or how it might compare to the Philips?

Also, I have heard that some people are using Bendix 6900s in place of the 5687 Tunsgarams. Same questions here if you have any input.

Thanks,

Frank
fmpnd
Sorry, I mixed these tubes up in my original post. The Phillips are the 5687s and the Tungsrams are the EZ-80s.
After this last weekend, the tube configuration on my AMR CD77 is Philips 5687 in the rear, Mullard CV4024 (12AT7) in the middle, and RFT EZ80 in the front. I have heard good things about the Bendix 5687, but haven’t had a chance to audition them. This past weekend I had some extra time compared four different sets of EZ80’s (front position).

Tesla – rolled off highs & lows; very warm; sounded like a screen was placed in front of the speakers. I was not impressed at all.
Brimar – similar to the Tesla, but not quite as warm and not as rolled off at either end. The mid-range is where these tubes excel.
Tungsram – great extension both top & bottom, but poor density. Music had a hallow sound, like listening through a pipe. Also has a bit of boost in the upper mid-range. I had used these previously, but was never happy with them.
RFT- Magic time! This is by far the best tube I have tried in this position. Voices are real; in the room with you real! Thunderous bass, excellent midrange and a delicate high end. If one can find fault with them, it would also be a bit of push in the upper midrange, but far less than the Tungsram. Mind you, I’m knit-picking (but isn’t that what we all do with this “hobby”?). I plan on adding a third set of damping rings to the tubes – my guess is that it will help control it a bit.

Remember, no tube is perfect. All have their strengths and weaknesses. What works in my system my not work in yours. You really have to experiment to find out what’s best for you. In my opinion, this is one of the great strengths of the AMR; you can customize it to your liking. Also, you can easily move the damping rings to different points on the tubes to make even finer adjustments to the sound. Additionally, if your machine is not a 77.1 (the current version), you can have Darren Censullo of Avatar Acoustics modify it to the new standard – a substantial improvement!
Thanks Kgproperties! You and I must have similar tastes. Your description of the Tungsram sound is exactly what I told Darren yesterday. I reviewed the original version of the AMR for Stereo Times and just had Darren send me the .01 update (with Tungsrams). I still have both players.

I am having a hard time finding the RFT EZ-80s. I have a friend loaning me some Telefunken EZ-80s and Bendix 6900s to try. It sounds like the RFTs may be what I am looking for from your description. Do you have any sources for the RFT EZ80s?

Regards,

Frank
I have tried a bunch of EZ 81 rectifiers in my system and the old Mullards are King. The plain old RCA's are also very good and probably less rare and precious. Now, according to Cary, the EZ 80 is a direct drop in replacement for the EZ81's in their SLP 90 preamp. I am not sure however if we can assume that to be the case in all equipment and applications. Perhaps someone else out there could enlighten us on that question. I was told they have exactly the same electrical specs. What does the tube reference manual say?