Hi,
With all due respect but there is no such thing:
Nope, once again, Ei (Novak in ex-Jugoslavia) and RFT in East-Germany where Philips subs.
Cheers, 😉
With all due respect but there is no such thing:
Nope, once again, Ei (Novak in ex-Jugoslavia) and RFT in East-Germany where Philips subs.
Cheers, 😉
Of cource what I meant was that Ei etc..... were making tubes for Telefunken too.Ei did not have Philips old machinery only,but older Telefunken also.
Haven't you seen any Teles with the diamond on the bottom?All German telefunkens have it....that is "West German" of cource back then......
The ones that look like ECC88 were the Tele ECC803 not the ECC83
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Hi,
Again, with respect:
Sure, but none of those were ever made outside TFK's own factories, let alone in communist countries such as former Yugoslavia.
In short, when there's a diamond shaped mark between the pins, you can be sure it's made by TFK. When not it can, could or more likely is not made for or by TFK.....
60% of the tubes out there are just "fraudes", you know. Sad but that's how it went.
Cheers, 😉
Again, with respect:
Sure, but none of those were ever made outside TFK's own factories, let alone in communist countries such as former Yugoslavia.
In short, when there's a diamond shaped mark between the pins, you can be sure it's made by TFK. When not it can, could or more likely is not made for or by TFK.....
60% of the tubes out there are just "fraudes", you know. Sad but that's how it went.
Cheers, 😉
I'm not saying anything different than what you say.
From what I read long time ago,Tele (first) and Philips (later) machinery,went to Ei after they stopped producing tubes in their countries.
Ei-made smooth long plate ECC83's had 4 seams on top of the glass(philips "sign" ),smooth plate(tele "sign" ) but no diamond mark.
Perhaps at some point they(Ei) were using a combination of both Philips and Tele machinery ?
I have never seen an original Philips ECC83 with long smooth plates,at least not yet.
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True, but you can still get grid current. This is because of two effects:fdegrove said:
1. different metals for grid and cathode set up a built-in potential (SY can explain, he is a chemist)
2. the hot cathode means you have a thermoelectric generator.
Grid current shoots up once the grid goes positive, but in small signal circuits it is important to ensure that the grid is not merely negative but also sufficiently negative. This seems to be not as well known as it ought to be. The 'knee', where the current starts to go up, is typically in the region -0.5V to -1V but varies from one valve type to another and also from one sample to another. It can also change with ageing. My guess is that a high mu valve will suffer more from this, because the grid is very close to the cathode.
Thanks for all the comments.
The reason for the enquiry was to seek a suitable valve for a valve/mosfet hybrid amp. I would be using one half of the valve to provide all of the voltage gain required (32dB) and the other as a cathode follower buffer. This would then drive a complimentary pair of mosfets for the output stage. (No overall feedback).
Noting that Croft Acoustics successfully uses the ECC83 in their hybrid amps, it seemed a good place to start. My simulations using the Norman Koren spice model indicate that the required gain can be achieved with the following parameters:
HT = 220V
Anode current = 0.4mA
Anode load = 220k
Cathode degeneration = 1.5k
Distortion at 60Vpp = 2% (mainly 2nd harmonic)
However, some of the comments so far suggest that getting the best out of the ECC83 may be somewhat fraught, so suggestions for alternatives would also be welcome.
The reason for the enquiry was to seek a suitable valve for a valve/mosfet hybrid amp. I would be using one half of the valve to provide all of the voltage gain required (32dB) and the other as a cathode follower buffer. This would then drive a complimentary pair of mosfets for the output stage. (No overall feedback).
Noting that Croft Acoustics successfully uses the ECC83 in their hybrid amps, it seemed a good place to start. My simulations using the Norman Koren spice model indicate that the required gain can be achieved with the following parameters:
HT = 220V
Anode current = 0.4mA
Anode load = 220k
Cathode degeneration = 1.5k
Distortion at 60Vpp = 2% (mainly 2nd harmonic)
However, some of the comments so far suggest that getting the best out of the ECC83 may be somewhat fraught, so suggestions for alternatives would also be welcome.
As a general rule, closer grid pitch is what increases mu, while closer grid-cathode spacing increases transconductance. They are interrelated, but the general rule holds.
I used an ECC83 to drive a MOSFET source follower, cascoded, which it did easily. It's a very good way to use this tube.
Will it drive any mosfet source follower (to my knowledge not all mosfets have the same input capacitances).
Will it drive a non cascoded source follower as well?
In other words, would it be good to see what must be driven in this particular case (configuration; input capacitances)?
Maybe the OT can indicate?
I haven't tried it with every possible source follower. It worked very nicely with a cascoded IRF820.
0.4 mA current and 1k5 cathode resistor is - 0.6 V grid voltage.
Apart from the already mentioned grid current, this grid voltage is not enough to accept line input levels like the max 2VRMS (5.6Vp-p) delivered by the average CDP.
I know that in practice the volume control will attenuate before the input tube, but nevertheless it is poor engineering.
With todays sources there should be at least - 3V grid voltage; ECC83 is nice for a phono preamp, not for a line level input stage IMHO.
Well, if you bring feedback to the cathode, you can successfully use ECC83 as a line amp, though it would not be my first choice. Your comments about a low Vgk are quite apt.
Best uses for this tube in my experience are RIAA, in applications where the input capacitance isn't critical (e.g., second stage), and input tube for power amps using a 5-20 topology.
Best uses for this tube in my experience are RIAA, in applications where the input capacitance isn't critical (e.g., second stage), and input tube for power amps using a 5-20 topology.
Hi,
Yes, I heard that too but that alone does not suffice to make a valve to the same high standards TFK could.
Those smooth plate EI were often branded as 7025 which they in fact were.
EI was one of those rare (probably the only one) to manufacturer some etc.
typical US tubes such as a 6FQ7...
They were pretty good tubes but hard to come by unless you could buy by the ruckload and go through the Kafka hassle of dealing
with an Eastern-European country....😀
That said, other than the good sounding TFK, Philips and some Mullards you could try Philips ECC808 (6KX8) or the even harder to find E283CC.
Cheers, 😉
Yes, I heard that too but that alone does not suffice to make a valve to the same high standards TFK could.
Those smooth plate EI were often branded as 7025 which they in fact were.
EI was one of those rare (probably the only one) to manufacturer some etc.
typical US tubes such as a 6FQ7...
They were pretty good tubes but hard to come by unless you could buy by the ruckload and go through the Kafka hassle of dealing
with an Eastern-European country....😀
That said, other than the good sounding TFK, Philips and some Mullards you could try Philips ECC808 (6KX8) or the even harder to find E283CC.
Cheers, 😉
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There is an additional 1k (decoupled) which brings the overall grid voltage to around -1V. As mentioned, I only have simulation results currently, but these indicate that it is fine with a line level input. Remember the negative feedback means that the grid and cathode are (substantially) varying together.
The cathode follower can easily cope with 60Vpp into the mosfet source follower without slew rate limiting. This is for Exicon mosfets.
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