2. amps-preamps
  3. 148665-78452

Need a preamp?

Hi all, 

I have an older Cary tube preamp and a Bob Latino ST70 with a built in attenuator driving a pair of Proac D30R. The combo seems to be a tad too warm so I tried using the amp without the preamp and it seems to sound better with a wider soundstage and more extended highs. I have a phono amp also so I can also listen to LPs and cds. Is there a reason I need a preamp other than the convenience of switching between the two?  Would a ss preamp or passive preamp add to the sound?  I presume any preamp would only degrade the quality and can't make it better than it is. 


jaferd
gregm
3,405 posts
 
We use a preamp in order to drive the amp adequately, as well as for attenuation & switching between sources. One of the problems that may arise without a pre is that the source device does not have a powerful enough output to drive the amp. But, from your own description
I tried using the amp without the preamp and it seems to sound better
it seems you do not have this problem. So, go pre-less, why not :)?
(BTW, have you tried running the phono into your amp, and can it drive the amp?)
georgehifi's avatar
georgehifi
10,312 posts
 
jaferd

Is there a reason I need a preamp other than the convenience of switching between the two?
No your Bob Latino ST70 has an input impedance of 280kohm and sensitivity for full wattage output of just 1v in.
With these sort of specs you only need a passive preamp


Would a ss preamp or passive preamp add to the sound? I presume any preamp would only degrade the quality and can’t make it better than it is.
Yes any active preamp will add colouration to the sound.

Just use the built in attenuator as the volume control, and use an input switch box, like this
http://www.goldpt.com/sw4.html

Or leave your attenuator full up and just get a $49 Schiit Sys which has two switchable inputs, you’ll be fine with your cd’s, and you’ll have enough volume with your phono preamp as well if it’s high enough gain.
https://www.schiit.com/products/sys

Cheers George

atmasphere's avatar
atmasphere
11,841 posts
 
The Cary is not the most neutral preamp around IMO. So a passive would work quite well in your situation as you already know. I think you can get switch boxes to switch between inputs. Since you already have an internal volume control in the amps (which is the best way to go if you go passive) then the switch box is all you need- if switching the inputs manually is too much of a hassle.
jaferd OP
44 posts
 
Thanks for inputs. Would the Schiit degrade or color the sound more than the Goldpt cause it's so much more affordable. Also, would either give worse sound than just switching the inputs manually and using the attenuator? Just for my own education, do passive preamp color the sound at all and what about cables? Are there any affordable, I mean in the 300 dollar range, used cables I should look for that do not add coloration?  
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