ECL86 or ECL85 for mini amp?

[Jeroen211]

I know the ECL86 (in triode mode) is a good sounding tube for making a simple SET mini amp with. Just curious if an ECL85 would do even better? Any experiences soundwise?

 

[JonSnell Electronic]

The ECL85 was designed and optimised for frame oscillator and output in television receivers.

The ECL86 was designed and optimised for audio, both triode and pentode sections. The 'sound' has nothing to do with triode/pentode mode, it is due to circuit design.

I wouldn't entertain the ECL85 for this job.

 

[jhstewart9]

I wouldn't entertain the ECL85 for this job.


Why?

 

[kodabmx]

I would. Frame output tubes are quite linear and capable in triode connection, and the ECL85 (6F5P) is cheap and plentiful compared to the expensive and now kind of rare ECL86 (6GW8)

Someone already did SET with it, too.
6F5P SET Amplifier.
SPICE Design of 6F5P SET Amplifier

6 for 15$ 6pcs 6F5P (6Ф5П, 6VG8, ECL85) Vacuum Triode-Pentode HI-FI AMP Tubes, NOS, USSR | eBay

 

[Lampie519]

ECL85 makes a good driver, and yes, it can be used in an audioamp, but that was not the question. You asks if would be better...
No, it will not be better. The simple fact is that you would have to make a different output transformer and the triode has less gain, the ECL86 is half an ECC83 and a EL84 combined. So easy to get a good amp.

 

[jhstewart9]

Starting from zero means none of that matters. The sound will be whatever your speaker system does with the amp output.

 

[Kay Pirinha]

ECL86 is half an ECC83 and a EL41 (not EL84!) in a common envelope.


Best regards!

 

[Lampie519]

Sure it does, as a transformer for a EL84 can be found easy. Do you have a transformer lying arround in you junkbox for a ECL85? It would surprise me. Yes, any transformer can be used to get some output, but again, that was not asked, wasn’t it?
Why people can not just answer what was asked in the first entry?
How difficult is that?

Best regards, Frank

 

[Kay Pirinha]

Confusing EL84 with EL41 won't help either.
Best regards!

 

[davorin]

ECL85 makes a good driver, and yes, it can be used in an audioamp, but that was not the question. You asks if would be better...
No, it will not be better. The simple fact is that you would have to make a different output transformer and the triode has less gain, the ECL86 is half an ECC83 and a EL84 combined. So easy to get a good amp.

ECL86 is half ECC83 end EL41 or EL80 combined, but not EL84!

 

[Lampie519]

Yes, that is true, then again, the same output transformer can be used for all of these tubes but not for an ECL85 as the internal resistance is way off and will not make it a better amp (as this was the question)

Best regards, Frank

 

[Jeroen211]

Thanks. I know the ECL86 was designed for AF and is the obvious choice. But there are a lot of ECL85 amp schemes on the net that claimed to be good too.

In my case I am just curious because I use the pentode in triode mode. The ECL85 triode might then be a better driver as it resembles half of an ECC81.

 

[davorin]

ECL85/6GV8-XCL85/9GV8-LCL85/10GV8-PCL85/18GV8 is a very good tube for audio amplifiers, very linear, with lower internal resistance and with lower supply voltages uses an output transformer of lower primary impedance (read: cheaper!) than the tube ECL86 / 6GW8-PCL86 / 14GW8, which is much cheaper and lighter to procure.
The improved ECL805 / PCL805 variant, which has an increased maximum platee dissipation (especially from TELEFUNKEN) of Pa = 11W, is even better, but it is also increasingly difficult to find.
The attached data refer to SE-class-A with the cathode feedback of the output tube connected to the 16 Ohm secondary terminal.

 

[Jeroen211]

ECL85 is a very good tube for audio amplifiers, very linear, with lower internal resistance and with lower supply voltages uses an output transformer of lower primary impedance (read: cheaper!). The improved ECL805 variant, which has an increased maximum plate dissipation (especially from TELEFUNKEN) of Pa = 11W, is even better, but it is also increasingly difficult to find.

Interesting as I have a few NOS Telefunken ECL805's lying here. But my OPT's are for EL84 alikes so I think I will stick with the ECL86 right now.

 

[Tubes4e4]

Hi Jeroen,

I know the ECL86 (in triode mode) is a good sounding tube for making a simple SET mini amp with. Just curious if an ECL85 would do even better? Any experiences soundwise?

ECL85 / 6GV8 /PCL85 / PCL805 / 18GV8 pentode section strapped as triode can make a very nice and compact 5 Watt push pull amp. The rather lowish plate resistance helps with even rather "cheap" iron. Using decent iron, I prefer it to triode strapped PP using E/PCL86 any day.

I built several amps with that tube.

Kind regards, Tom Schlangen

EDIT: Uh, you were asking about SET, not tridoded PP. Anyway, my plate curves should be of help

 

[Kay Pirinha]

If you want to run the ECL85 power pentode at 250 V plate voltage and 36 mA plate current, you can try a 7kohms OT. If you've got a ECL805 and run it at 250 V and 42 mA, hence 10.5 watts plate dissipation, the OT needs to transform to 6 kohms as a rule of thumb.
Best regards!

 

[Jeroen211]

Thanks anyway. I also have good experiences with trioded ECL86 PP in a Lafayette LA224 Stereo.

 

[Merlinb]

Why people can not just answer what was asked in the first entry?
How difficult is that?

Difficult, because the question does not mean anything. What does 'do even better' mean? Nothing and anything.

 

[Jeroen211]

If you want to run the ECL85 power pentode at 250 V plate voltage and 36 mA plate current, you can try a 7kohms OT. If you've got a ECL805 and run it at 250 V and 42 mA, hence 10.5 watts plate dissipation, the OT needs to transform to 6 kohms as a rule of thumb.
Best regards!

These OT impedances are not that different as with ECL86. My OPT's are probably 7k so I think it is worth trying it. I run them on 300V/30mA...

 

[Shoog]

To be honest the ECL82 is far more appropriate for audio, is cheap and plentiful. Great sounding amps at up to 10Watts in PP can be easily achieved.

Shoog