Valves

[toms wait]

I am researching small signal valves.
The AI 500 has 2 ECC88's and a ECC83.
Is an ECC88 the same as a E88CC?
I have read that an E88CC can be used instead of ECC88 but be wary the other way around.

Also if an E88CC is equivalent to a 6922 then presumably it too can be used instead of ECC88.

Any knowledge or experience on this out there, thanks.

 

[toms wait]

Sorry this looks to be done to death like cable threads.
I'll search instead of writing and blabbing.

 

[rabski]

E88CC and ECC88 are not equivalents. They're close, but the maximum plate voltages and some of the inter-plate allowances are notably different. The plate curves are also not the same, so the ideal operating points are not identical.

The E88CC (and variants such as 6922, Cca and others) have higher ratings, so can usually be used where an ECC88 (6DJ8, M3624, etc.) goes, but not always the other way round. They're quite close, but there are a few things that differ notably, such as the maximum cathode to heater voltage, which has caught a few people out.

Always check with the designer. A quick email to Guy at Puresound, and he'll be able to confirm.

 

[toms wait]

E88CC and ECC88 are not equivalents. They're close, but the maximum plate voltages and some of the inter-plate allowances are notably different. The plate curves are also not the same, so the ideal operating points are not identical.

The E88CC (and variants such as 6922, Cca and others) have higher ratings, so can usually be used where an ECC88 (6DJ8, M3624, etc.) goes, but not always the other way round. They're quite close, but there are a few things that differ notably, such as the maximum cathode to heater voltage, which has caught a few people out.

Always check with the designer. A quick email to Guy at Puresound, and he'll be able to confirm.

I put 6922's in and it sounds ok. I am trying to get rid of a left channel light crackle by changing valves. The 500 was designed with ECC88's and ECC83's so at least it the right way round for swapping.

 

[Redtube]

This left channel light crackle problem appears to be somewhat common, so does anyone have any clear idea what is the most likely cause, the clue might be the fact that it appears tha the left channel in affected in all cases that I have come across?.

 

[pmcuk]

Left channel? Pure coincidence I suspect.

Crackles can sometimes be valves, and there is no "clear idea" of what causes this. But your first stop will be connections.
- dirty/oxidised connectors like valve pins and sockets, RCA etc. connectors
- poor or dried up solder joins
- loose or badly attached wires anywhere in the system

So clean all connections, look at your cables and tighten all screws.

Inspect for bad joints if you are familiar with working on tube equipment and know the usual safety procedures. Re-solder as necessary. Take a multimeter and check all the voltages between channels to see that they match. Obviously this isn't for those who aren't skilled in valve circuits and schematics.

You may or may not get a clearer idea by swapping everything you can between left and right channels. This might hopefully localise your search.

It would be useful to have a sticky on this from e.g. Rabski who knows this stuff pretty well.