2. amps-preamps
  3. 1176738136

Lack of bass with SP-9 MK3

I've just acquired an AR SP-9 MK3 and my short-lived excitement quickly faded. While the depth and highs are crisp and more detailed than my old GTP-500II (Adcom), the lows are uneventful to say the least.

Granted the Adcom had the Contour enabled, this preamp's lows seem non-existent. I suppose there's a chance that I've been listening to exaggerated lows, but I've tried running various genres through the unit with same results. Is the unit faulty or will new valves fix the issue?

Any suggestions would be much appreciated!
fourrings000bfd
sherod
1,690 posts
 
I would compare your output impedance of the preamp to match with the input impedance of your amp. A simple adjustment of cap values in either might be just the ticket, assuming you are going to keep the amp.
schipo
1,268 posts
 
SP-9s all have whimpy power supplies along with most of the new Audio Research gear. Stay with the older stuff it is built much better.
mitch4t's avatar
mitch4t
1,610 posts
 
I had and SP9 Mk3 a few years ago and I kept it for about a week. Way too thin all over. I couln't get rid of it fast enough.
fourrings000bfd OP
2 posts
 
Thanks for all the responses. Looks like there isn't much that can be done since so many people had a similar experience. My main goal was to make sure that these characteristics are inherit of this particular unit rather than the neutral, tubed design in general.

Sherod -- the SP9 should be fairly well matched with my Adcom 5802, see the specs below. My understanding is that the desired minimum ratio is 10:1.

GFA-5802: 10k/105k Ohm(balanced/unbalanced)
SP-9: 250 Ohm
audphile1's avatar
audphile1
4,966 posts
 
fourrings00@yahoo.com, the input sensitivity of the amp is 1.7v.
On the preamp - CD Input to Main Output gain is 9db.

Could the out gain be a bit low for the preamp to drive your amp?

You can try switching your cd player from cd input to any available high-level input and you should get 21db of output gain. See how it sounds then.
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