Amplifier Conundrum

[chris trainor]

Hello - I recently purchased a Pioneer Elite SC-81 receiver to pair with my Martin Logan Source speakers and Grotto sub. A friend told me to get an amp to fuel the speakers with more power, so I bought a Speakercraft BB275 on Craigslist. I hooked it all up yesterday and while it sounds good, I need to crank the volume knob more to get the same volume when the separate amp is connected. I was assuming the amp would be additive power and not replace the power provided by the Elite SC-81. Did I make a mistake getting a separate amp with less power than the amp in the receiver? Thanks so much.

 

[markw]

No, they are not additive. The external amp replaces the one in your receiver.

And, as far as your volume control setting, different input sensitivities between the Pio's internal amps and your external one could account for the difference. The lower the sensitivity, the higher you'll need to crank the volume but, rest assured, I'm pretty sure it will drive that amp to it's maximum.

And, yeah, you should have gone with an external amp with at least twice the power your receiver can put out.

 

[mtrycrafts]

Hello - I recently purchased a Pioneer Elite SC-81 receiver to pair with my Martin Logan Source speakers and Grotto sub. A friend told me to get an amp to fuel the speakers with more power, so I bought a Speakercraft BB275 on Craigslist. I hooked it all up yesterday and while it sounds good, I need to crank the volume knob more to get the same volume when the separate amp is connected. I was assuming the amp would be additive power and not replace the power provided by the Elite SC-81. Did I make a mistake getting a separate amp with less power than the amp in the receiver? Thanks so much.

Mark is right. Your Pioneer has more power than what you added to it.
If you can, send it back. Stick around and learn about audio.
By chance your friend mention what kind of amp or power to get?

 

[KenM10759]

Is it a no-no to use the pre-outs of a receiver to output to an amp for the L-R mains, and then if the speaker is capable of bi-amping add the outputs of the amp to that of the receiver? If not, why? I don't know if I've ever seen that done, and not tried it myself.

I could imagine a slight time delay, maybe milliseconds, but it could be there.

 

[markw]

Is it a no-no to use the pre-outs of a receiver to output to an amp for the L-R mains, and then if the speaker is capable of bi-amping add the outputs of the amp to that of the receiver? If not, why? I don't know if I've ever seen that done, and not tried it myself.

I could imagine a slight time delay, maybe milliseconds, but it could be there.

So, you're saying that you want to use the receivers internal amp to power one part of a bi-amp capable speaker and an external amp (in parallel) to power the other section?

That would work fine as long as the jumpers are removed from the speaker terminals and the two amp channels never, ever are joined. Hopefully, the gain of both amps will be similar so both speaker elements play at the same level.

There will be no time delay.

 

[KenM10759]

No external jumpers on my speakers, just a cool, easy to use internal mechanism activated by turning two knobs. Clockwise, connected. Counterclockwise, disconnected. I wouldn't do that because the whole point of adding an additional amp is usually to take a load off the receiver and have more power available to the remaining channels. Hence the need to make sure the amp you add for mains is at least as powerful as what the receiver was putting out. I was just curious.

 

[PENG]

No external jumpers on my speakers, just a cool, easy to use internal mechanism activated by turning two knobs. Clockwise, connected. Counterclockwise, disconnected. I wouldn't do that because the whole point of adding an additional amp is usually to take a load off the receiver and have more power available to the remaining channels. Hence the need to make sure the amp you add for mains is at least as powerful as what the receiver was putting out. I was just curious.

Those knobs work the same way as the jumpers though not as good because you can't see/access the internal connections.

Before you proceed, as Mark said, make sure the output from the external amp and the receiver's outputs are exactly the same or very close. If they are within 1 dB you likely won't notice. For the R500, I suggest you use the external amp to feed the bass drivers, assuming your amp is at least twice as powerful as the receiver.

 

[KenM10759]

Not as good because I can't see them? I trust KEF's design implicitly but if in doubt there's this high tech tool I have, labeled "Fluke 85III" which can verify.

I'm not doing this right now though looking at an NAD C275BEE. Considerably more power than what my receiver puts out and at 2.5x the rating I wouldn't need to bi-amp anything.

 

[PENG]

Not as good because I can't see them? I trust KEF's design implicitly but if in doubt there's this high tech tool I have, labeled "Fluke 85III" which can verify.

I learnt not to trust anything unless I have no choice, so yes I measured mine with my Fluke 87V (neither the 85, 87 are accurate enough). It is easy to verify that they are separated, just not easy to verify when the jumper is connected, that it makes a perfect connection. My suggestions is, turn it close tight, and leave them alone for good.

I'm not doing this right now though looking at an NAD C275BEE. Considerably more power than what my receiver puts out and at 2.5x the rating I wouldn't need to bi-amp anything.

No, there is no need then. The 275 has the ability to kill the R500.

 

[markw]

No external jumpers on my speakers, just a cool, easy to use internal mechanism activated by turning two knobs. Clockwise, connected. Counterclockwise, disconnected. I wouldn't do that because the whole point of adding an additional amp is usually to take a load off the receiver and have more power available to the remaining channels. Hence the need to make sure the amp you add for mains is at least as powerful as what the receiver was putting out. I was just curious.

Sorry to have offended you. I don't know the construction of every speaker on the market, nor did you specify what they were.

From your poorly worded newbie question and postulation, I responded in as clear a fashion as possible to answer your question and avoid any confusion. Now, if you want to get pedantic about it with me, you should have known the answer before asking the question.

 

[KenM10759]

Mark, no apologies needed, no offense taken. I'll update my profile to add the list of speakers and other bits so folks will know what I'm driving.

PENG, yes the C 275BEE could blow up my KEF R500 speakers and I'm well aware. No fears. Just like me driving my (now extant) 2004 Pontiac GTO, I never used all it's power or it could've killed me. I wish NAD had a modern, straight power amplifier like that one at a little less power for a lot less money.

 

[fmw]

Mark, no apologies needed, no offense taken. I'll update my profile to add the list of speakers and other bits so folks will know what I'm driving.

PENG, yes the C 275BEE could blow up my KEF R500 speakers and I'm well aware. No fears. Just like me driving my (now extant) 2004 Pontiac GTO, I never used all it's power or it could've killed me. I wish NAD had a modern, straight power amplifier like that one at a little less power for a lot less money.

There is always something like this.

 

[PENG]

Mark, no apologies needed, no offense taken. I'll update my profile to add the list of speakers and other bits so folks will know what I'm driving.

PENG, yes the C 275BEE could blow up my KEF R500 speakers and I'm well aware. No fears. Just like me driving my (now extant) 2004 Pontiac GTO, I never used all it's power or it could've killed me. I wish NAD had a modern, straight power amplifier like that one at a little less power for a lot less money.

No I wasn't worry about you killing your beloved speakers, just trying to highlight how powerful that NAD amp is, relative to the little R50's.