just opened up my carver tube cd player due to a slipping loading tray belt and a weird fuzziness on highs on one channel. i was going to replace coupling caps for the tubes with PIO's. the coupling caps on the tube board are 2.2mF

do they really need to be that big? i'm used to seeing 0.47mfd or similar for audio coupling.

I think you mean they are 2.2mmF, or uF. 2.2mF would be really large.

I would stick with or increase the capacitance value, rather than slimming down. The capacitance on a coupling capacitor will set your low frequency limit.

they are labeled 225k. online calculator claims that its a 2.2uF (2.2 micro farad)

most coupling caps i have seen in gear are 0.47. why would they use such a high value in this player? output tubes are ecc83.

my initial post may have been confusing with the 2.2mF.

FWIW, i think that the diverse labeling of capacitance is shameful. i can tolerate it up to a point, say the 1960s, but after that the SI system of prefixes should've been instituted on electronic component labeling as a general rule. why it still continues today is completely beyond me.

Yes, "225k" I believe means 2.2^5 picoFarads, which is 2.2^2 nanoFarads, which is 2.2 uF.

But I'd stick with those values if you're going to replace them.

FWIW, i think that the diverse labeling of capacitance is shameful. i can tolerate it up to a point, say the 1960s, but after that the SI system of prefixes should've been instituted on electronic component labeling as a general rule. why it still continues today is completely beyond me.

And this would help how? I have at work a pair of "smart tweezers" that reads nano farads. :thumbsdn:, when it should read only micro or pico.

just opened up my carver tube cd player due to a slipping loading tray belt and a weird fuzziness on highs on one channel. i was going to replace coupling caps for the tubes with PIO's. the coupling caps on the tube board are 2.2mF

do they really need to be that big? i'm used to seeing 0.47mfd or similar for audio coupling.

Is that the Carver 490/T CD player? Maybe not......I recall mine using two 6DJ8.....

mike,

youre right, ecc88. had to wipe the dust off the tube. its a 490/t. bought it new in 1992.

KE4MCL is on track for 2.2 mf

Yes it is big!! 2.2mmf would not pass any low frequencies.

Fred

KE4MCL is on track for 2.2 mf

Yes it is big!! 2.2mmf would not pass any low frequencies.

Fred
2.2milliFarads :sigh: You sure about that? Where is this cap in circuit? Is it connecting the signal path? What is the load? The load and the cap will determine the critical frequency. ...the -3dB low frequency corner.

For a 2.2mmF (or 2.2uF microFarad) feeding a 10k ohm load, the low frequency corner is 7.2Hz.

A 2.2mF into the same load is 0.0072Hz:scratch2:

And this would help how? I have at work a pair of "smart tweezers" that reads nano farads. :thumbsdn:, when it should read only micro or pico.

not sure i catch your drift...but perhaps i mistyped a bit. i was really talking about using the proper SI abbreviation for the prefix, like "mF" for milli-Farad or "uF" (u=mu) for micro-farad, etc.. instead what you often see for microfarads are things like "MFD" (i like picturing a Mega-farad cap!) and "mf," especially older pieces :nono: the "225k" is also confusing but in a different way. i realize that often they are short on space with the small caps, but on big electros, don't you think that "39 mF" is better than "39,000 uF"? now, my sampling of newer caps isn't that large, so i may just be complaining about exceptions to the rule.

anyway, SI rant ended, since it's really not that big of a deal :no:

we just get used to it. In the olden days, picoFarads (10^-12 F) were labeled "mmf" (for micro-microFarad), and the old hands (e.g., my father) referred to the units as "micro-Mikes".

To get back to the original question it is no doubt a load issue. It is not unreasonable to suppose that a CD player might be used with a solid state amplifier. If the Zin of the load is 1/10th as much then approximately 10x as much capacitance is needed to keep the low frequency response up to snuff. The line level devices with 0.47uF output caps were no doubt intended for connecting to vacuum tube devices which typically have Zin of 100K or more. SS devices often run Zin of 10K-20K.

mike