Tube for CAT Mk3

I just retubed my CAT Mark 111 with NOS Mullard ECC88(6922) and NOS Mullard CV4004(12AX7). In my system, the Mullards improved the midrange and overall dynamics. They are also very quiet both in the line and phono stages. The only drawback of course is the cost. NOS Mullards are getting harder to find. I have also used Amprex 6DJ8(6922) with excellent results.(you can not use the 6DJ8s in the V6 and V7 postions secondary to difference in plate voltages)Good luck.

I bought a CAT SL-1 III used, and sent it back to the factory for a phono stage. It had two NOS tubes replacing 6922's, and the factory told me that was a bad idea, that they weren't rated to handle the current the 6922's in that position would get. So I'd check with the factory on where it's SAFE to use other than 6922's. They're very friendly and helpful. Phone number: (716) 359-2700.

Oops, I see that the responder before me warned you already, and more specifically than I could, about voltage ratings. Sorry to be redundant.

Best 6922/6dj8/7308 Siemens 7308/ECC188.A freind who has tried over 20 different tubes from the 6922 family recomended it.Its is the best tube i have ever heard.I put it in the Output stage of my CD Player.The same night my wife sat down and after a few seconds was asking what ihad done to the system.She commented that i must of spent a thousand + to get this improvment.

Call Kevin Deal at upscale audio.Ask him about NOS Radiotechniques.They are great for CAT's

CAT owners beware... Please note that when using different equivalent as for the 6922 at position V6 and V7, you are in risk of blowing a couple of fets. this has happened more than once in my CAT,[recently MK 3 upgraded] so as i read about a guy who throws in 20 [!] different brands/equivalents and thinks everything is workin'fine....it sure get's my heart rate up. You may do this searchin'and trying just to get a 'sound' but the CAT has a specific design around the V6 V7 6922, and so uses very closely matched Sovtek reflector series. this is recommended by the factory, and for reason. If you are able to get amperex or siemens or whatever NOS thats ok, but you are indeed one in a million lucky guy who still can come up with a pair which are up to spec's for use at V6 V7 DON'T SAY I DIDN'T WARNED YOU... if in doubt call Ken Stevens [CAT] or Kevin Deal from upscale audio. Happy CAT owner for 7 yrs, wouldn't trade it for any other Enjoy. Ron [the netherlands]

Hi Superclamp, I think you and I met on another thread over this very same issue. I am a CAT Ultimate owner. Since the manual only says no US 6dj8's at positions V6 and V7, I would be very interested to know exactly what CAT told you is and is not acceptable at those positions. You and others on this thread seem to be suggesting that not only US 6dj8's, but perhaps all 6dj8's and all other 6922 equivalents (like the 7308/E188cc and the cca) and even 6922's from brands other than Sovtek (and perhaps Amperex or Siemens) are forbidden. I realize that I will have to give Ken Stevens a call, but considering the rather terse, and not very clarifying warning in the manual, your warning is not very understandable. Can you or perhaps anyone else who has specific knowledge of what is and is not allowed at V6 and V7 shed a very bright light on this subject. How, for example, could only certain brands of European NOS 6922 tubes be acceptable when this is not stated anywhere in the manual? I, too am a very happy CAT owner.

By the way Rec, it seems as per your post you are using Mullard ECC88's in V6 and V7. The ECC88 is the European designation for the 6DJ8. The ECC88 is not a 6DJ8 equivalent, but exactly the same tube as the 6DJ8. So, you are violating your own rule by using a 6DJ8 in V6 and V7. The E88CC (European designation), is the same as the 6922. Both the 6DJ8 (ECC88) and the 6922 (E88CC) fall into the same 6DJ8 "family" of tubes of which there are several others, including the 7308 (E188CC), the cca (This is the European designation. I don't think there is a U.S. designation.), the E288CC (European) and the 7922, etc. These "equivalents", while not exactly the same as either the 6DJ8 or 6922, are considered to be "premium versions" of the 6922. Generally they are considered to be safe to substitute for a 6DJ8/6922, but there are exceptions with certain equipment and certain circuits. The warnings of Superclamp and others notwithstanding, all of these tubes will produce a different sound in the CAT. The Telefunken cca at V6 and V7 produces the best sound I have ever heard from the CAT Ultimate. However, I am sticking with Telefunken 6922's (E88CC) in V6 and V7 until I get this V6 and V7 thing fully understood and resolved. Can anyone speak in detail about what the CAT can and cannot accept in V6 and V7 and why, reconciling this information with the extremely brief and unrevealing information in the CAT manual?

Yes, I am aware the the ECC88 is the same as a 6DJ8, I spoke with CAT and they said not to used the US 6DJ8 but the European ECC88 would be fine. It seems to work in my system. I am pleased with the sound.

Thanks very much Rec for replying. This corresponds with my understanding of the manual, that only US 6DJ8's are forbidden in the CAT MK III or Ultimate in V6 and V7. I will still call CAT in order to find out about other members of the 6DJ8/6922 family like the 7308/E188CC or the cca in order to see if they are forbidden at positions V6 and V7 or elsewhere like at V1,V2, V5 and V10. I will post the results of that inquiry here.