[tanchiro58]

Hi Everyone or Owners of the Promitheus Apollo preamp,

I just got the Promitheus Apollo preamp and tried to swap the 6N1P tubes with RCA 6922s Germany. I heard that both tubes are equivalent (Nicholas told me too). But since I put the RCA 6922s to the preamp immediately I heard a distortion noise like buzzy sounds out of my speakers. Should I replace any resistors and/or capacitors to match with the 6922s or 7308s?

Have anyone tried this before to any preamp and/or Promitheus Apollo preamp? Thanks in advance for your inputs and helps. I would appreciate your time and your experience.

Best regards,
Tan

[martyo]

Hi,

I have AVA gear with 6N1P's and from everything I have read and heard because of the much higher heater current on the 6N1P's you can substitute the 6N1P's for 6922's but not the other way. I would just check with the manufacturer of your preamp first. It's not your speakers, they were fine before the tube change I presume.

Frank probably saved me alot of money when he upgraded to the 6N1P's, no NOS to roll. 

[yo2tup]

Hi,


Frank probably saved me alot of money when he upgraded to the 6N1P's, no NOS to roll. 

my set amps use 6N1P's as drivers and they can be rolled NOS e80cc tubes just fine 

[F-100]

Tanchiro58,
  I swapped out the 6N1P with 6922 tubes on the Promitheus Apollo amp today and it humps like hell. Definitely not a good match. 

[Steve]

"I have AVA gear with 6N1P's and from everything I have read and heard because of the much higher heater current on the 6N1P's you can substitute the 6N1P's for 6922's but not the other way."

Maybe I am reading things wrong, but I believe you wrote this backwards, but I understand what you meant.  One can replace the stock 6N1P with a 6922, but not necessarily the opposite. The filament current, as you mentioned is much higher in the 6N1P than the 6922.

Take care.

[JoshK]

Word to the wise.  The 6N1P has a bit different parameters than the 6922-odes, even beyond the higher filament current.  The 6H23P is closer (equiv) to the 6922.  Some people believe that the 6N1P sounds best in a circuit made for it rather than the 6922.  If AVA designed for the 6N1P then it could likely sound best with the 6N1P.  Its a good tube btw.

[alotaklipsch]

MY BAD UR RIGHT

[JoshK]

TRY E182CC, OR BENDIX 6900, AND SMILE

Those are totally different tube types though, they are more 5687 like.  For that you could try the 6N6P which is very similar to the 5687 family (with 6922 pinout).  But the circuit should be optimized for this type.

[KBK]

You can find these tubes from various vintages and manufuacturers, by shopping on ebay. I've dealt with most of those tube resellers, they are good folk. Please don't educate them as to what they have in their hands - I like my cheap pricing. (the vast majority have NO idea of what they are selling..which is bargain drug pricing of tubes to tube-o-philes)

[zacster]

Don't kid yourself about these sellers.  EBay is a good market indicator of real value.  If they were worth more, they'd cost more. 

I bought Amperex Bugle Boys 6DJ8 from a dealer for $15/ea, and even he thought that was high.  There are a lot more of those around than you'd think if you only listened to the audiophiles.  He had lots on hand too.  OTOH, some tube types are truly scarce.

The 6N1P is generally considered to be a high heater current equivalent to the 6DJ8/6922/ECC82 family.  You cannot substitute by using a 6N1P unless  you know you've got the extra current.  You can always add a filament transformer if you really want to use them.  The other way around is fine.  If it was built to take a 6n1p you can use a 6dj8 or 6922 without problem.

[tanchiro58]

If it was built to take a 6n1p you can use a 6dj8 or 6922 without problem.

Zacster,

I have tried the RCA 6922 gold pins made in Germany to replace the 6N1P in the Promitheus Apollo preamp and they sound distorted to my speakers. Nicholas at Promitheus Audio told me he uses Amperex 6922s without any problems. 

Tan

[Steve]

I checked out the data sheet. Interesting because the transconductance is only listed at 4450 uhmo vs 12k for the 6922s, mu is similar, 35 vs 33.

But the plate curves are close to the 6922. Something is not right somewhere as the bias voltages are not that much different between the tubes, yet calculations from transconductance and mu would indicate otherwise.

Thanks for bringing up the differences Josh.

[JoshK]

Steve,

It seemed funny to me too that gm was lower but Ih is so high, seems a bit of a waste of energy. Although I know they aren't as related as mu & Ip are to gm.  Or is it mu*Ik?  I forget.

[JoshK]

Wait, that's dumb...current is preserved, so its the same thing.   

[tanchiro58]

Wait, that's dumb...current is preserved, so its the same thing.   

JoshK,

If so, why I heard the distorted sound out of my speakers when I use RCA 6922s in the Promitheus Apollo preamp?

[Steve]

Has to do with variables, like plate voltage, RL etc, the design.


Take care.