Actual Receiver Frequency Response (1 Viewer)

[Dennis B]

I was wondering if anybody knows the actual frequency response of the Marantz SR7200 which I'm using as my pre/pro or how I could measure it without the influence of my room.
I've done extensive ETF testing on my speakers and room, primarily at low frequencies, and am starting to worry about the mid to high freq band now.
It's really weird that for all conditions that I've logged so far, the full bandwidth frequency response of the room + speakers starts to roll off at about 8 kHz all the way to 20 kHz in an almost straight line, with an amazing 25 dB difference between these two points. :frowning:
I'm using an RMB-1075 as my amp and B&W 602s as my main speakers, and for both the specs are very good all the way up to 20 kHz. For the 7200 I have no such spec, there's nothing in the manual or the web, so that's why I'm asking about it.
Could this possibly be right?
Thanks,
Dennis

 

[Brandon B]

8kHz is really low.

However, I do have a Sony Prologic receiver that states 20-20k, but is definitely rolling off severely above 15kHz (as compared to all the same equiipment with the Sony replaced by a Norh preamp)

I'd look at your cables or something else to be rolling off that low though.

BB.

 

[Dennis B]

Thanks, Brandon, but I'm using AudioQuest Type 6s. I've also tried lamp cord, but it behaves the same. It's also not the amp, because I got the same thing before I even got it, but since I was so busy looking at low frequencies, I never paid attention to it.
I also got a very early reflection showing up on ETF, at about 0.5 ms and very strong. I'm still working on where it's coming from. Could it possibly be blamed for the first problem?

 

[Brandon B]

A smoothly sloped in room cancellation starting at 8K seems pretty unlikely, to me with my limited knowledge anyway. (I assume that's what you meant by maybe the delay causing it.)

Defect in the Marantz processing?

I'd post this in the DIY area too, as more guys in there are familiar with this sort of stuff.

BB