Effect of IERC coolers on SQ

[john dozier]

I have just had the oddest occurence. I have a pair of modified (teflon and styrene caps) ASL Monsoons with 8 EL34s each. I just installed some IERC tube coolers on the EL34s. I cannot believe how much the SQ improved. Smoother highs, better definition, better soundstage replication, the whole nine yards. Can someone explain this-lack of microphonics in tubes perhaps? I am at a loss. Thanks and regards

[kevinkr]

I use some smaller IERC coolers/shields on driver and small signal tubes. I suspect the design of the shield with its multiple fingers damps the envelope effectively, also obviously reduces or eliminates effects of EMI on the tube as well.. I haven't tried them on power tubes so I can't imagine what the story is there.

They're pretty pricey even for surplus NOS or used on eBay so I try to grab them at ham fests for chump change whenever I can.

[john dozier]

I was lucky as I picked them up on the bay for about $3 each. They are the only ones I have ever seen that fit EL34's. I am still surprised by the improvement. I doubt it could be measured by traditional means. Regards

[kevinkr]

You really lucked out!

[trobbins]

Originally Posted by john dozier

I doubt it could be measured by traditional means. Regards

If you had a digital cro and could store an 'input side' waveform, and an 'output side' waveform (ie. on either side of the EL34 stage) then you could do a scale and subtraction and attempt to set up and look for non-harmonically related noise, or noise of a particular frequency that was persistent with change in input signal.

Best if you remove any feedback that would attempt to reduce any EL34 induced distortion.