The vast majority of audio mods made to a transceiver includes a re-scaling of audio coupling capacitors and/or resistors. Although the Panasonic FC series has been used in many mods, I have begun using Nichicon caps -- most recently when I was modifying my Elecraft K3's ESSB Rx and Tx audio response.
The K3 uses only 10uF of series capacitance from an otherwise excellent headphone driver stage to the headset. My goal was to use as a high a capacitance value as possible while still being able to insert the caps into a high density SMT/SMD area on the K3's front panel where the existing caps are located. I selected a Nichicon FW series radial cap whose value is 330 uF @ 10 WVDC.
Fifteen years ago, I would have never considered an eletrolytic cap under 25 WVDC. Historically, the failure rate of low WVDC caps was quite high -- even when the applied voltage was substantially less than the cap's specified voltage rating. But time and technology has marched on to the point where today's low-voltage electrolytic caps are very reliable.
Although I am an advocate of using these high-quality caps in audio circuits where reasonably high current exists (e.g., headphone and speaker circuits), I am less inclined to use them for intra-stage coupling.
The importance of low ESR caps can be justified in the higher current applications, but when a low-Z source is coupled to a very Hi-Z input, the use of low ESR audiophile-grade caps simply cannot be justified. In these applications, I will oftentimes use any generic electrolytic type or even the sacrilegious tantalum if the coupling Z is high enough.
Other excellent audiophile-grade caps in the Nichicon MUSE family include FG, KG, KZ and ES series (non-polarized). Links to other Nichicon caps appear in the next reply message.
Paul, W9AC
Audiophile-Grade Capacitor Upgrades
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Terrific News!
Howdy Paul,
Welcome to the Forum!!
Glad to have ya around.
Your input will be greatly valued.
We haven't tried the Nichicon caps compared to the Panasonic FC series as of yet.
More due to the fact that we determined the Panasonic FC was the best 'cost to sound' winner a few years back, and now that's the stock we have on hand here.
Looks like we're going to have to acquire some Nichicon caps to make an audio comparison on the next mod victim.
Yes, we agree about the use of the lower rated WVDC caps, but it's still a little nerve racking to install a lower voltage rated cap into a circuit.
There is just something 'Not Right' about it, hahahaha!
We will have to adamantly disagree with you on the use of High Quality Low ESR caps for inter stage coupling. The proof is in the Sonics.
We've rolled too many into circuits for testing purposes and the result is always the same, it's just plain better sounding.
There is better clarity, Frequency extension, tone, and overall sound stage.
Of course using NO coupling caps would be the best, but we all know that there necessary.
Also the Sonic Effect of adding better caps throughout the AF Audio chain is cumulative.
We have gone to the extreme of replacing the XR7 and NPO Ceramic SMD inter stage coupling caps with Polyphenylene Sulphide Film SMD caps.
The result was a noticeable improvement in Audio Quality.
Thanks for the links.
We'll get some on order and try them out.
Take Care,
Welcome to the Forum!!
Glad to have ya around.
Your input will be greatly valued.
We haven't tried the Nichicon caps compared to the Panasonic FC series as of yet.
More due to the fact that we determined the Panasonic FC was the best 'cost to sound' winner a few years back, and now that's the stock we have on hand here.
Looks like we're going to have to acquire some Nichicon caps to make an audio comparison on the next mod victim.
Yes, we agree about the use of the lower rated WVDC caps, but it's still a little nerve racking to install a lower voltage rated cap into a circuit.
There is just something 'Not Right' about it, hahahaha!
We will have to adamantly disagree with you on the use of High Quality Low ESR caps for inter stage coupling. The proof is in the Sonics.
We've rolled too many into circuits for testing purposes and the result is always the same, it's just plain better sounding.
There is better clarity, Frequency extension, tone, and overall sound stage.
Of course using NO coupling caps would be the best, but we all know that there necessary.
Also the Sonic Effect of adding better caps throughout the AF Audio chain is cumulative.
We have gone to the extreme of replacing the XR7 and NPO Ceramic SMD inter stage coupling caps with Polyphenylene Sulphide Film SMD caps.
The result was a noticeable improvement in Audio Quality.
Thanks for the links.
We'll get some on order and try them out.
Take Care,
Voodoo Guru
From Deep in the IDD of the Sub-Harmonix Realm
From Deep in the IDD of the Sub-Harmonix Realm
Re: Terrific News!
> "Of course using NO coupling caps would be the best, but we all know that there necessary."
Unfortunately, most amateur radio gear does not use bi-polar power supplies on the audio chips. When op-amps are powered by +/- dual-polarity supplies, then coupling caps can be completely eliminated through the use of servo control to eliminate inter-stage DC offsets.
Servo-controlled audio in these applications would be the Ne-Plus-Ultra If one were to really take an audio upgrade to the extreme, it would call for the upgade of the audio power supplies to bi-polar types. Probably the most significant benefit is that ultra-clean audio from headphone and speaker drivers could then be employed using bias temperature compensation on complimentary-symmetry transistors. Headphones and speakers fed from this circuit requre no coupling caps.
> "Also the Sonic Effect of adding better caps throughout the AF Audio chain is cumulative. We have gone to the extreme of replacing the XR7 and NPO Ceramic SMD inter stage coupling caps with Polyphenylene Sulphide Film SMD caps."
Another option when the coupling Z is high (and ample cabinet room exists) is the use of metalized ploypropylene or metalized polycarbonate capacitors.
I have to admit that once I get to the 90% point in the audio upgrade on this equipment, I call it quits. IMHO, there are just too many other factors inside amateur radio equipment that acoustically mask further qualitative improvements (e.g., the use of single-ended power supplies), including upgrades to better quality SMD/SMT types. Still, the attempt is educational and can be rewarding to some in knowing that they've done everything possible to extract the "nth" degree of audio improvement from their equipment.
Paul, W9AC
Unfortunately, most amateur radio gear does not use bi-polar power supplies on the audio chips. When op-amps are powered by +/- dual-polarity supplies, then coupling caps can be completely eliminated through the use of servo control to eliminate inter-stage DC offsets.
Servo-controlled audio in these applications would be the Ne-Plus-Ultra If one were to really take an audio upgrade to the extreme, it would call for the upgade of the audio power supplies to bi-polar types. Probably the most significant benefit is that ultra-clean audio from headphone and speaker drivers could then be employed using bias temperature compensation on complimentary-symmetry transistors. Headphones and speakers fed from this circuit requre no coupling caps.
> "Also the Sonic Effect of adding better caps throughout the AF Audio chain is cumulative. We have gone to the extreme of replacing the XR7 and NPO Ceramic SMD inter stage coupling caps with Polyphenylene Sulphide Film SMD caps."
Another option when the coupling Z is high (and ample cabinet room exists) is the use of metalized ploypropylene or metalized polycarbonate capacitors.
I have to admit that once I get to the 90% point in the audio upgrade on this equipment, I call it quits. IMHO, there are just too many other factors inside amateur radio equipment that acoustically mask further qualitative improvements (e.g., the use of single-ended power supplies), including upgrades to better quality SMD/SMT types. Still, the attempt is educational and can be rewarding to some in knowing that they've done everything possible to extract the "nth" degree of audio improvement from their equipment.
Paul, W9AC