On 1/10/2011 11:19 PM, dhsatyadhana wrote:

...and this just in! I just tried out all of my ULRs with my Grado SR-60 "near-audiophile" and fairly power-hungry headphones, with the volume attenuator. I did A/B tests on various stations here in the Seattle area, and the clear winner from an audio perspective is...

What could cause significant differences in audio when all these small
portables, Eton, CCrane, Tecsun, that I've dissected use the same CD1622
audio output chip and the same value caps, resistors, etc. in the audio
circuits? The circuits are all identical in the 7 different radios
I've examined and are straight out of the CD1622 datasheet posted in the
files section. Using quality headphones is obviously the way to test
them, but it still leaves me wondering what the determining factors
could be. Kiwa and Big Sky Audio have kits to improve the audio in
communications receivers which involve replacing polarized electrolytic
caps in the audio stages with non-polarized electroylitics and ceramic
caps with mylar. I could understand if Tecsun was using a better
quality cap, or design, than say Eton, but from what I've seen, that
isn't the case. Maybe it's just a case of variables in the particular
batch of CD1622s, caps, etc. In that case, my PL-380, or CCrane SWP may
be my audio winner. Using good headphones is definitely the way to
enjoy FM and also pull out the weak ones while DXing MW.

The CD1622 is made for low coast small footprint portables not for
audiophile quality sound. Anyone looking for sound comparable to high
end tuners is not going to find it in a $50 portable radio. These are
truly "pedestrian" radios meant to sell at a price that the average
Chinese worker can afford and not aimed at the US/European audiophile.

I would think Silicon Labs has a high standard of quality control and
the audio response out of one Si4734 would be very close to that of
another.

Anyone else have any ideas regarding what Kevin and others are noting?

Rick W4DST