Any audio circuit designer who is trained to listen critically and bothers to try may observe that electrolytic capacitors from different manufacturer’s series will sound different in the same application. Yes, we are comparing caps of the same value, voltage rating, size/density, and general construction technique. Even though said manufacturers’ data sheets may show the same specifications, and we may not be able to measure any differences in-circuit, two similar parts will still sound different. Knowing this, I and my close colleagues will choose carefully the electrolytic capacitors that we use to recap vintage equipment and manufacture new equipment. Empirically, we have come to prefer certain product lines, and because often we can not isolate their effects through electronic testing, we are auditioning by ear alone*.
[*Of course we are first limiting our choices to those caps which possess the necessary other characteristics, such as temperate rating, ripple current, etc.]
This is not news. Several third parties have written about the subjective qualities of capacitors in audio, and many smaller manufactures offer premium product lines said to possess superior sonic qualities. However, it is exceedingly rare to find mainstream manufacturers of capacitors not only acknowledging the existence of audible effects, but also publishing actual data explaining why. Thus, it is with great pleasure that I share the following link:
(See section “7-2 Audio Equipment”) Panasonic electrolytic capacitor construction affect on sound quality
Just add water…
This is a trick John Klett taught me for testing power supplies and power amps under load. Instead of using a bulky, expensive power resistor and having it get really hot, you just put a regular 1/4W metal film resistor in a glass of tap water. Here I have 47 ohms drawing about 1 Amp from a 48V DC power supply. I’m doing this to test the noise rejection of an inline L-C filter circuit we designed. The numbers on my AP show an improvement of up to 50 dBu after filtering, which seems to leave the TDK-Lambda “line lump” working just as well as an Acopian Gold Box alternative. Hello compliance!
We received fifty of these chassis today for NLA product. It appears Sansak and I made no mistakes in the drawings, and neither did our excellent fabricator in interpreting them. Hooray!
Here’s what my bench is looking like this week. You’ll notice the NLA FT development PCB I talked about drawing is now tangible and stuffed full of components. It looks like a mess (you don’t want to see the rats nest of wires underneath!), but it’s sounding beautiful and proving our theories as it should. Note the peculiar frequency response shape (pink noise source, 1/3 octave display) on my DK meter – just one of many possible settings. From this controlled chaos will come a new, non-linear way to EQ.
Emmitt said we need to mount all of our transformers for the NLA product on a pair of interior bulkheads, but he didn’t say which transformers, before disappearing again. Sansak suggested best to play it safe and put them all on there… because disappointing E.P. is not an option! Of course, overlaying transformer footprints is nothing new for me, but it requires a lot of holes no matter what. While the resulting panel is only about 3 x 17 inches, we had to draw it using four pages of ARCH C (18 x 24″) in order to fit all of the dimensioning. Here’s a partial screen shot of page one:
I’ve been working at EXILE since 2005 and taking photos the whole time. Now I’ve finally gotten around to organizing these photos, and will be posting albums in the photos page of eisenaudio.com.
Just finished drawing the development PCB for an upcoming NLA product. We’ll use this to optimize all the building blocks individually, and then experiment with chaining them together. Eventually we’ll work out the useful permutations and reduce the result into a compact PCB for the 8 channel production version. Keep nonlinearaudio.com on your radar. We’ll be debuting at the AES convention this fall.