How many watt amp to drive 4ohm bookshelf speakers?

Bryan R

Bryan R

Active Member
Hey all,

I'm pretty new to the speaker world, not very educated yet I'm afraid. :P Ready to learn, though!

I can't seem to find easy-to-understand discussion of matching amplifier watts and speaker ohms anywhere.

I have a pair of 4ohm Sony speakers that I'd like to get an amplifier for (hopefully a t amp, if possible), but am clueless as to the best/necessary wattage to drive them. :drool:

Also, would it be possible to get such an amplifier that I could upgrade to 6 or 8ohm speakers in the future without having to get a full blown amp as opposed to a t amp?

Sincerely,
Confused
 
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Dear Confused:

Can you tell us what model the speakers are? Then we or you can search and see what specs they might have and what their limits are as far as wattage are concerned.

Yours truly,
Tom
 
OvenMaster said:
Dear Confused:

Can you tell us what model the speakers are? Then we or you can search and see what specs they might have and what their limits are as far as wattage are concerned.

Yours truly,
Tom
Click to expand...

Sure!

They're actually from an older JVC micro system, the model number on the back is SP-UX1000GR.

Looks like impedance is indeed 4ohms, it says power handling capacity is 20 watts... So I don't want to exceed 20 watts in each channel, correct?

Does this mean I could purchase a t amp with the ability to go up to 40 watts, as long as I never turn the volume up past halfway? Would that ensure different (and more robust) speaker options in the future using the same t amp?

And how do ohms fit into all of this?

Thanks,
Bryan (Less confused)
 
I take it no reply because I'm spot on...?

Of course I'm still confused about ohms and voltage and whatnot...
 
You probably don't have anything to worry about. I suspect you could run those on a 3 wpc tube amp or a 100 wpc solid state amp, and it would just be a matter of where you turn the volume control to get the sound level you want. The key is don't push amps into clipping. If you turn anything up and quality of sound goes down back it off.

Matching speaker ohms to amp output is more of a concern with tube amps. For solid state, for most speakers rated 4, 6, 8 ohms you won't have a problem.

Speaker sensitivity (some say effeciency) is where one could have a concern with the amplifier wpc. Speakers with sensitivity of for example 95db need less power to attain the same volume level of a speaker with a sensitivity of 84db. Most speakers are somewhere in the middle and most receivers will deal with them just fine.

The other thing you said was about turning the volume knob half way to get 20 watts out of a 40 watt amp. I don't think that's the case but it really doesn't matter, for most speakers just a few watts can be quite loud.
 
That micro system is rated to deliver 15Wpc to the speakers, so a standard T-Amp, like the one available from parts-express.com would be ideal. Just don't expect it to fill an auditorium with sound.
 
chicks said:
That micro system is rated to deliver 15Wpc to the speakers, so a standard T-Amp, like the one available from parts-express.com would be ideal. Just don't expect it to fill an auditorium with sound.
Click to expand...

Thank you very much!
It just needs to fill a small bedroom. :)
Should I just go ahead and get a 15 or 20 watt t amp?

The reason I ask, is if I got a 40 watt t amp like this:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=248-462&vReviewShow=1&vReviewRand=882995

would it be better compatible with most better speakers in the future while still being suitable for the JVCs (as long as I am mindful about clipping and don't ever turn up the volume all the way)?
Or is 15 watts sufficient for most other box/bookshelf speakers anyway? Sounds like it'd be too weak to me.

Basically the JVCs may just be temporary, holdovers until better speakers are found/chosen.

Thanks so much for your help.
~bryan
 
What causes clipping is when you try to push an underpowered amp, not when you put too many watts into speakers. So if you were to get an amp that was too small, and push it to extremes, you would cause it to clip. But if you get the 40wpc that you listed, you shouldn't have a problem as long as you're not listening at insane volume levels. Speakers are almost always rated conservatively - your JVC speakers, even though they're rated at 20w, could probably easily take 30 or more, so there's really not much to be worried about.
 
i would go ahead and get the 40 watt so if you upgrade to better speakers in the future, the power will be there. like others have said, just be careful with the vol. knob. once you start to hear distortion, back it down a little bit.
 
tmad: Didn't know this before, thanks for the knowledge. :)

All right, sounds like a plan.

Thanks so much, everyone.
 
T amp

I bought two of these to mess around with and I can can you they have a remarkable sound.
http://shop.ebay.com/?_from=R40&_trksid=m38&_nkw=HLLY+TP-20+
If you buy one though click the Ebay link here on AK to get there first. I think AK gets a little kick back for that.
I run this little amp with Boston HD9 speakers that were found at GW for 4.99 and are 90DB efficient. You won't blow the roof off or get huge thumping bass but the sound is so clean I actually listen to it more than my main system. With just a volume knob and no controls for tone it is amazing.
Cubdog on here just got the 90w version and I think he is going to run it for a while and report back. The one he got is just the board but makes for a nice DIY project and is very inexpensive.
 
Heck, I'm running my main stereo on 8 watts. Even with Indignias (not the most efficient speaker) they do more then fine.
 
Bigkahuna said:
I bought two of these to mess around with and I can can you they have a remarkable sound.
http://shop.ebay.com/?_from=R40&_trksid=m38&_nkw=HLLY+TP-20+
...
I run this little amp with Boston HD9 speakers that were found at GW for 4.99 and are 90DB efficient. You won't blow the roof off or get huge thumping bass but the sound is so clean I actually listen to it more than my main system.
Click to expand...

Yeah, definitely. I'm watching that first auction, the tab's been open in my browser for a couple days now. ;)
I've heard good things about the HLLY T's.
Any idea how high the auction might get? I really don't wanna pay much more than $55, any chance I'll get lucky or is it guaranteed to exceed that? :P
 
Bigkahuna said:
Cubdog on here just got the 90w version and I think he is going to run it for a while and report back. The one he got is just the board but makes for a nice DIY project and is very inexpensive.
Click to expand...

The Tamp-90 is a complete unit. I'll post some pictures in my thread soon.

cubdog
 
Reasonable price Hlly

Bryan R said:
Yeah, definitely. I'm watching that first auction, the tab's been open in my browser for a couple days now. ;)
I've heard good things about the HLLY T's.
Any idea how high the auction might get? I really don't wanna pay much more than $55, any chance I'll get lucky or is it guaranteed to exceed that? :P
Click to expand...

I paid a little more than 40 bucks for each including shipping from two different sellers.
 
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