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6dj8 to 7dj8

macman007

macman007

Mcintosh..Made In USA
I'm fairly new to tubes but I love 'em. Just dont know a ton of stuff about them. I have a bottlehead seduction phono pre I built about 3 years ago.The other day i was looking for new tubes and found 7dj8's that were supposedly compatable with 6dj8's. Is this true? What should I expect if i use them? is there an advantage? Will it improve or degrade the sound? Will it damage the unit? Do any of you recommend a specific tube for the bottlehead based on personal experience?

So many questions, so little time.........

Artie :scratch2:
 
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7DJ8 will work in any 6DJ8 circuit... as long as it doesn't require maximum cathode emission. So if ithe circuit runs HOT (high current, near maximum ratings), forget it. Since it has a higher rated filament voltage, it will be like running the 6DJ8 at 5V or so.
 
7DJ8 are better and last longer.

:yes: Like you i'm also new in tubes,but since i bought a Musical Fidelity passive preamp i have tried a lot of tubes.
I tried 6DJ8,6922,6AQ8,NEWS,NOS,and JAN and let me tell you the best ones in my system are the 7DJ8/PCC88 NOS Philips.The lows more tight,the mids more open and the highs like crystal. :smoke:

Have fun
 
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Filament voltage is the same according to the data, but the current is about 1/3. Pin out is the same, but the 7 is a high frequency while the 6 is a high MU. I would think that if the filament can handle the current the difference is going to be that the 7 will amplify the higher freqs more than the 6 will. Question is are the freqs in the audible range?
I can't find the info on the filament current but Wardsweb probably knows.
 
Triode CD line stage.

Hey 6647

as i said before i am new in this big world of tubes,but in my opinion a passive preamp works allmost the same way as an active preamp without any equalizer knobs. :scratch2:
It does the "tube magic". :thmbsp: For those who wonders a expense CD player can do, this is a very inexpensive way to improve an audio system. :D
The Muscial Fidelity X10-D is connected between my NAD C521BEE CD-Player and an integrated amp T40 from british Highend manufacturer Myryad.

Sounds impression is massive . The clarity and deepness of the sound stage is absolutely amazing. It seems as if the sound sources vanish into the room as if you're experiencing the concert real live. :smoke:

I cannot understand why Musical Fidelity discontinueed production :sigh: of these "really" improving sound devices.

Maybe "passive preamp" is not the right technical word for it,maybe "triode CD line stage" is more like it.

Ciao.
 
Your MF is a tube buffer stage.

All of my line amps run 6DJ8/6922, and I've rolled everything out there.

The Creme de la creme is the Amperex 7308, if you can find them. The Sovtek 6922 is the best current production tube. The 1986 NOS JAN 6DJ8 is my recommended 'best buy'. The offer great low end and control, an articulate midrange, without the touch of high end harshness that the majority of current production tubes to. That, and they are affordable also.

I've rolled some 7DJ8's, and haven't been impressed thus far.

Cheers,
Russ
 
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mhardy6647 said:
Pardon my ignorance (which is genuine)... but why does a passive preamp have any tubes in it?
Click to expand...


It is powered and is if I read correctly using 2 dual triodes with either one tube being the amp and the other set up as SE or 1/2 of each. Single volume knob it is mainly for headphones but can be a line stage. I guess there are OPTs in it. It is a very low power SET.
 
"PCC88 Twin Triode" not 7DJ8

Thanks Russ for the tip about the Amperex. :thmbsp:

...But i was wrong about the 7DJ8.Instead the 7DJ8 you must read "PCC88" this is the tube i was talking about - "PCC88 :yes: Twin Triode" - wich i think is different from 7DJ8 wich i've never tried before.As you know in Europe we have another names for valves,that's my confusion. :scratch2:

Do have you tried PCC88 NOS Philips ?!
My second choise are ECC85 Telefunken. :thmbsp:

Thanks Thatch,for your simple but pratical explanation about passive preamps. :yes:
Ciao.
 
My anthem pre 2L uses the 6dj8/6922 tube and I've used everything under the sun in
this unit and to me mullards sound the best. Everyone has different gear and different
tastes so there really is no "best" tube for all situations.

The 7dj8 works just fine in my system and my understanding is it can handle a higher
filament voltage so supposably they will last longer. As far as sound goes again I did
prefer the mullard 6dj8 in my system but yours may vary, you just need to hear them.
 
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