Rick Robinson <w4dst@...>
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?