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MC240 Restoration

I had a pair of 240's in the mono mode pushing my Bozaks in the 60's but I wanted to bi-amp so I traded them for 275's. A much better sound I thought. I then went with 2100's, and I didn't like the bass. So I went with Crown amps for the next 30 years or so. I'm back with Mac amps for the last 10 years. They will out live me for sure.
 
twiiii said:
I had a pair of 240's in the mono mode pushing my Bozaks in the 60's but I wanted to bi-amp so I traded them for 275's. A much better sound I thought. I then went with 2100's, and I didn't like the bass. So I went with Crown amps for the next 30 years or so. I'm back with Mac amps for the last 10 years. They will out live me for sure.
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I’ve had many combinations of Amp’s and Speakers, most have been current or up to date, I have to say that going Vintage has Really turned me around and what I consider Audio Nirvana....so far the marriage of the twin 240’s and MX110Z with High Efficiency speakers have resulted in an audio experience I have never been faced with. I am a new Fan of vintage Audio and my ears don’t lie!!
 
I run my MC40's with vintage Altec speakers. Yummy.
So did you ever compare the original caps to the Russian PIO's? I was interested in your opinion.

BillWojo
 
Hated to start a new thread for a subject that has been covered time and time again so I'll ask my question here. I'm recapping my MC240 and really want to leave the black beauties in, however all four of them are measuring in the .260uf range (should be .22). That is well out of the +/- 10% tolerance of a new one. I'm measuring these with a Fluke meter and any new caps that I measure are spot on, so I believe my meter is accurate.

I have read that these need to be tested at their normal operating voltage, but I'm assuming that only applies to leakage? Unfortunately I don't have a real capacitance meter.

Thanks
 
lakebilly said:
Hated to start a new thread for a subject that has been covered time and time again so I'll ask my question here. I'm recapping my MC240 and really want to leave the black beauties in, however all four of them are measuring in the .260uf range (should be .22). That is well out of the +/- 10% tolerance of a new one. I'm measuring these with a Fluke meter and any new caps that I measure are spot on, so I believe my meter is accurate.

I have read that these need to be tested at their normal operating voltage, but I'm assuming that only applies to leakage? Unfortunately I don't have a real capacitance meter.

Thanks
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The main problem with the striped BBs is electrical leakage throwing the tube stage operation points off and affecting the operation.
If you are going to pull them to test, you may as well just order a recap kit from Jim McShane and be done with it.
Also, you can cut to the chase on the carbon composition resistors and replace them all with properly rated metal film types, or at least measure them all and replace the ones out of tolerance.
 
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The only way to really test a cap is at full rated voltage.

I’ve tested many Black Beauties at operating voltage and approximately 60% were out of spec by >10%.
 
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