Comparing the tuner section of Sansui 2000x and Sansui TU-d99x tuner

[rasenthiran]

Hi guys,

I was able to come across a Sansui 2000x Receiver last week. Love the sound of this little receiver but what surprised me is the tuner section. I found the stereo separation,reception and selectivity better than the TU-D99x. Sansui TU-D99x has better bass and clarity but Sansui 2000x fm stereo broadcast can be feel as we are listening to a cd player. Any comment and view is appreciated. Looks like the build quality of the Sansui 2000x plays a very important role,part here.

Raj

 

[Trnsfmr]

I have also noticed that a lot of older tuners sound better than new ones. I've put a lot of effort into understanding this, and have identified a few reasons.

The 2000 has an IF strip made up of several tuning coils and 10.7 Mhz amps cascaded together. This is to get selectivity. Starting somewhere in the mid 70's most manufactures switched from this type of IF to using ceramic filters in place of the can tuned coils. The problem with the ceramic filters is that they do not have uniform response or group delay across their pass band. Essentially the filter response is "jagged" and not smooth.

Ceramic filters can be selected for the ones that have better response. High end tuners use these more expensive hand picked filters, but they still do not have the innate smoothness of a tuned coil. Bad group delay means that along with the jagged response curve, the phase curve also jumps around and is not smooth. All this affects the final signal we get out of the FM demodulator.

I got interested in this when I restored an Eico ST97 tuner from the 60's. I did it for nostalgic reasons and wasn't expecting anything unusual regarding sound quality. The ST97 uses a tuned can IF strip of course, but also uses a different decoding scheme than every other tuner I have studied since Fisher came out with their "chopper" decoder around the same time in the mid 60's. As far as I can tell, modern tuners use the same scheme, and thus all FM sounds equally bad to my ears.

I have a page about this on my site http://www.qrxrestore.com/fm-follies/

Glad you brought it up. Interesting stuff.

 

[rasenthiran]

Thanks for the explanation,learn something new today.I was very surprised with the Tuner section of this receiver.

 

[rcs16]

Bad group delay means that along with the jagged response curve, the phase curve also jumps around and is not smooth. All this affects the final signal we get out of the FM demodulator.

The ceramic filter group delay and response is noted. Thus you have an aural effect that is not easily measurable in the final audio spectrum.
The sansui TU-X1 is regarded as one of the best. I am sure you have studied the design. Not sure if you have one to listen to and compare. So you are saying that you believe that there are tuner designs that sound better than the TU-X1?
I guess the TU-X1 qualifies, as the wide band IF looks to be all tuned L/C ckts.
It does use a HA11223 stereo decoder.
Do you have the same opinion of SAW type IF filter group delay responses?