2. amps-preamps
  3. 116539-70778

New preamp, loss of low freq.?

Hooked up new preamp, and I lost what I think is some low freq slam. Reasoning behind this?
i have been rewarded with the best cleanest, accurate midrange/highs I have ever heard, but did lose some low frequencies.      Normal?  

Sanders preamplifier is the new addition. 

Should i I hook up my equalizer to  smooth out, and add some low freq. 

it it is recording dependent, I still feel I lost some bass when sanders is in the mix. 

Not complaining, this has completely opened up my energy rc-70's, I have never heard these sound so loud, so clear before.   It's I feel I lost a few octaves in the lower register. 

Better? Leave it, I can definitely get used to this sound, as before it was a small bit boomy, maybe I just need time to adjust, and to let the pre warm up for a couple weeks. 

thoughts, recommendations, tweaks? I suppose I could move the speakers a little closer to the wall, this may add a little more bass. 
128x128arcticdeth
georgehifi's avatar
georgehifi
10,312 posts
 

Amp 10kohm, this could be the problem if your preamp is capacitor coupled on it’s output. As if the preamp’s output cap (if it has one), the size of it could have been calculated for a more normal (industry standard) >47kohm input impedance power amp.

Which the size of the cap may have been done so it’s say -3db at 10hz  with a 47kohm poweramp. Which is fine. 

But if that amp is 10kohm input then the -3db point will be 4.7 x higher at 47hz  easily heard and so will sound like it has a bass roll off. 

To test this, you can find out if the preamp is capacitor coupled by talking to the designer, or a quick test is to get another amp that you know is >47kohm input impedance and see if it still has a bass roll off.  


Cheers George

arcticdeth's avatar
arcticdeth OP
1,572 posts
 
Georgelofi;

Amp 10kohm, this could be the problem if your preamp is capacitor coupled on it’s output. As if the preamp’s output cap (if it has one), the size of it could have been calculated for a more normal (industry standard) >47kohm input impedance power amp.

Which the size of the cap may have been done so it’s say -3db at 10hz with a 47kohm poweramp. Which is fine.

But if that amp is 10kohm input then the -3db point will be 4.7 x higher at 47hz easily heard and so will sound like it has a bass roll off.

To test this, you can find out if the preamp is capacitor coupled by talking to the designer, or a quick test is to get another amp that you know is >47kohm input impedance and see if it still has a bass roll off.










So, I purchased a amp or preamp that is a mismatch? And won't sound good??  Wtf, I'm always fuc**ng something up. 
Tried for a stellar system, and always something wrong when I make a purchase,    Always!!!! Damn.

what is recommended? Sell preamp?

lowrider57's avatar
lowrider57
5,417 posts
 
George,
Yes, the amp's input impedance is extremely low at 10kohm, and is not a good match for this preamp. But the preamp's output impedance is very low, so an amp with an input impedance lower than 47kohm can be used for testing, correct?

If he can borrow an amp with an input impedance of >25kohm approx., it should be adequate for testing. Your thoughts?
lowrider57's avatar
lowrider57
5,417 posts
 
George,
From a design perspective, why does the McCormack have such a low input impedance?
arcticdeth's avatar
arcticdeth OP
1,572 posts
 
Yes, inquiring minds want to know............
More to discover