Replace ECC83 preamp valve with E88CC(6922)

[hillbear]

I have a Philips NOS E88CC valve - can it be used as straight swap for ECC83 ???????

[SY]

They're about the same physical size. They both are dual triodes. Every other parameter of the tubes is sharply different.

[bigwill]

While the pinout is similar the heater connections are different, too

[Skorpio]

Originally Posted by SY

They're about the same physical size. They both are dual triodes. Every other parameter of the tubes is sharply different.

Not correct...

The have compatible heater requirements, they are pin compatible....but....yes....

[bigwill]

So no they cannot be used as a straight swap for an ECC83

[joaquim]

Yes and no, depeding on nfb and fq, ECC88(E88CC, longer life span then ECC88). E88CC is a high frequency tube, and ECC83 is a AF(audiofq..) tube. So the answer is no, ECC83 isn't equal to E88CC... but try.. it might sound okay anyway, both tubes has 6.3V heater voltage and around 250 - 300V plate voltage.. but if it's fitted in th RF-stage in an old tube Radio, it want work, once again, ECC88 is an RF-tube, but you want to use ECC88 instead of ECC83, and it's not a straight swap, but it ought to work... again, try.. just make sure your not damge the tube or the next stage... I think I've actually used a ECC88 instead of ECC83 in a line amp for guitars look up the gm and the steepness on the tubes and compare, µ/S too...

Best of luck to you!

[hillbear]

Thanks for your input - but I am really none the wiser ! Does anybody have a definitive answer ????

[SY]

Yes, the definitive answer is they are NOT at all the same.

The have compatible heater requirements, they are pin compatible....but....yes....

Other than the ECC83 having a 12V heater and the ECC88 having a 6V heater, the ECC83 having a centertapped heater, the ECC88 not, and a 2:1 difference in heater current...

[rongon]

OK, I'm no expert, but I'll try to help...

The short answer is no, they are not interchangeable.

ECC88 = 6DJ8

ECC83 = 12AX7

ECC88 is a frame grid, high frequency twin triode. It has a low(ish) internal resistance (approx. 5000+ ohms) and is usually used with higher standing current (approx. 3 to 15mA) and relatively low anode voltage (65 to 125V). ECC88 mu (amplification factor) is rated at 33. ECC88 has a 6.3V heater (only) which draws 300mA (360mA for some 6922 or E88CC types).

ECC83 is an older design audio (low) frequency twin triode. It has a rather high internal resistance (approx. 70,000+ ohms) and is usually used with a very low standing current draw (approx. 1mA) and relatively high anode voltage (150 to 200V). ECC83 mu is rated at 100 (very high). ECC83 heater may be wired for 6.3V at 300mA or 12.6V at 150mA.

If your ECC83 is wired for 12.6V heater and you drop in an ECC88, you'll be putting 12.6V on your ECC88's 6.3V-rated heaters. That probably would not be good.

So while the two tubes have a similar base and pin-out arrangement, they are not substitutes for each other. You would need to re-design the circuit if you wanted to use ECC88 in place of ECC83.

Is this in a guitar amp? If that's the case, you could try 12AT7 (ECC81) or 12AU7 (ECC82). Usually no harm in that. If it's a hi-fi amp of some kind, then I wouldn't try it.

[Joshua_G]

Originally Posted by hillbear

Thanks for your input - but I am really none the wiser ! Does anybody have a definitive answer ????

There is no definitive answer.

From engineering point of view, the 2 tubes aren't swappable, ECC83 has a miu (amplification factor) of 100 while E88CC has a miu of 33, ECC83 has anode current of 1.2mA while E88CC has anode current of 15mA, ECC83 has transconductance of 1.6mA/V while E88CC has transconductance of 12.5mA/V. For 6.3V heater supply, with ECC83 it has to go 1 wire to pin 9 and 1 wire to pins 4 and 5 tied together, while with E88CC it has to go 1 wire to pin 4 and 1 wire to pin 5, while pin 9, which is shield, should connect to the ground.

However, should you take care of the heaters connections, you can try and swap the tubes. It may work and sound okay and may not work well.