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    the safety precautions around high voltages.

identifying valve 6N1 Pi-EB (an old useless rapirman cited them as 6DJ8 replacements?)

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tonescout

tonescout

Member
Joined 2020
#1
Looking at some equyivalents it looks more like an ECC85, and not sure if this is able to be used as an equivalent to an ECC88?

any ideas, or is this another f** up by the repair guy, that I used before I started doing things myself!

Thanks

Rich
 
#2
The 6DJ8 is a miniature nine-pin medium gain dual triode vacuum tube. It is distinguished by its very high transconductance, mostly the result of its frame grid construction. Versions of the tube are named ECC88, E88CC, 6922, E188CC, CV4108, 7308, 6N1P and 6N23P.
An ECC83 or 12AX7 has similar characteristics but different heater wiring; pins 4 & 5 6volts, pin 9 screen for 6n1 etc and pins 4 & 5 12volts with pin 9 centre tapping for heaters.
Your repair guy clearly had more knowledge than you, it would seem.
 
#3
tonescout,

The 6N1Pi has Aproximately:

1/2 the transconductance, Gm, of a 6DJ8
2x the plate resistance, rp, of a 6DJ8
2x the filament current of a 6DJ8

Similar gain, u
The same pinout

The ECC88, E88CC, 6DJ8, and 6922 are more similar to each other; Versus the distant cousin, the 6N1Pi

Just My Opinions


I have never used, and never seen an ECC85, so I have no opinions on it.
 
#8
Thanks everyone, and the reason I am asking is that I don't use them as I did not trust what this guy did/chose after discovering there was a series of fundamental errors created by the 'repair' that I fixed ONLY with your kind help on this forum [Thanks!]
I was tidying up my valve drawer and came across them and wondered if they could be used or what they were equivalent to 🙂
 
#10
JonSnell Electronic said:
The 6DJ8 is a miniature nine-pin medium gain dual triode vacuum tube. It is distinguished by its very high transconductance, mostly the result of its frame grid construction. Versions of the tube are named ECC88, E88CC, 6922, E188CC, CV4108, 7308, 6N1P and 6N23P.
Click to expand...
This is a direct quote from Wikipedia I assume, where later in the same wikipedia post it quotes it is not a direct equivalent, hence my desire to talk to the amazing combined knowledge on this forum 😀
 
#12
tonescout said:
This is a direct quote from Wikipedia I assume, where later in the same wikipedia post it quotes it is not a direct equivalent, hence my desire to talk to the amazing combined knowledge on this forum 😀
Click to expand...
Equivalents have all electrical caracteristics exactly or almost the same , not filament current twice , transconductance half and so on .
The problem with ECC88 is that being a highly desirable tube there is financial interest to invent cheap equivalents .
 
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#14
tonescout said:
Looking at some equyivalents it looks more like an ECC85, and not sure if this is able to be used as an equivalent to an ECC88?

any ideas, or is this another f** up by the repair guy, that I used before I started doing things myself!

Thanks

Rich
Click to expand...
6N1P != ECC88 != ECC85.
Heater voltages and pinout yes, heater current not, and different gm, u on all of them. You need to look at the specific use case. ECC85 and 88 were designed for operation in TV sets, 6N1P is mainly for audio.
 
#15
Saying that a 6N1P is equivalent to a 6DJ8 or 6922, ECC88, E88CC, etc., is just like saying that . . .

Ford and Chevy decided to use the same parts all the way from the transmission, clutch, driveline to the differential rear end axle.
The Only problem was, the Ford engine was designed to use a 4.11 differential, But the Chevy engine was designed for a 2.05 differential.
(Ford and Chevy did not really do that, but if they did, using the wrong ratio on the differential "works, but Very Poorly").

6N1Pi:
Transconductance 4,000 microMhos and rp 7000 Ohms; u = 33
(I have built amplifiers using the 6N1P; do not get caught by the errors on the Svetlana 6N1P data sheet; it says:
Gm 7000 uMhos; rp 4000 Ohms, the data sheet is completely wrong).

6DJ8:
Transconductance 12,500 microMhos and rp 2640 Ohms; u = 33

Do not only consider the same u, and the same pinout . . . Those are the only common specifications of the 6N1Pi to the other tubes.
If those two tubes are the same, then all differential rear end axles are also all the same ratio, 2.899:1 (geometric mean of 2.05 and 4.10).
(Your Mileage May Vary . . . and it Will Vary).
 
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#17
tonescout said:
Looking at some equyivalents it looks more like an ECC85
Click to expand...
The ECC85 was used as the front end in some FM receivers of the late 50s & early 60s.
It was used in the Eico HF90 Kit & came as part of a complete module with all the RF inside.
The raw 10.7 MHz was ready to use in the following IF Strip. The pre-built RF section sure
beat trying to line up a 3-gang open tuning capacitor at 100 MHz..
I built two of those kits pre 1960. One of them still runs most days in the workshop.
 
#19
That erroneous Svetlana data sheet mentioned by 6A6sUMMER in Post#15 has been misleading people for something like 25 years.

Bottlehead used it as a driver for a while, a couple decades ago. It sounds nice and is more linear than most of the mu=~35 double triodes, of which there are very many. We found that the sound quality often declined after around one year of use, and switched to others with better longevity.
 
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#20
OK - I think that concludes it then >
These 6N1 valves are of no obvious use to me, so if anybody is interested in the pair I have then let me know, they have been used by for about 2 hours before I pulled them out when the preamplifier came home accompanied by lots of hum from the repair and I wondered if these weird valves were the possible cause!

Thanks!
 
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