Is 25w/ch safe for bi-amping 340 se?

[choirbass]

Hi everyone,

I've been lurking for a while, but just a couple questions about the safest minimum wattage for each post when bi-amping 340 se's.

I have a 2 channel t-amp that is rated for 25w/ch, but know the 340's are rated for 35w minimum. Would 25w per post be enough to safely drive them without risking damage at all, even if they were driven loud?

I ask because a tweeter in an htm-200 se was damaged during a loud scene in LOTR, and didnt realize at the time that too little can actually be a really bad thing :(.


Thank you for any help,

Brandon

[choirbass]

Hm.. thinking about it again, I'm gonna have to assume that if ~20w was a minimum for 2 4" woofers, then 25w 'really' isn't going to be enough to safely power 2 6.5" woofers. Oh well, lol.

[Mag_Neato]

Actually, the 340's are BI-Wireable, not BI-Ampable.

So, that would mean running two sets of wire from a single amp, one set to each pair of binding posts with the post jumper plates removed. Bi-amping gets a bit more complex, requiring, I believe, an external crossover.

As long as you keep the volume within the limits of the amp the speakers will be fine. If you want to rock out then yes, more power is needed.

[choirbass]

Thanks :)

I had thought the internal crossover would manage which frequencies it was fed from a full range amp, and that the tweeter for instance essentially wouldn't attempt to drive anything below what the crossover is set to. And vice-versa for the woofers. Essentially not damaging either, but I might very well be wrong.

The binding posts were recently removed, and the internal crossover 'seemed' to handle things fine. Such as if I wanted only high frequencies, id just simply unplug the banana plugs from the +- of the woofers. Missing a lot of the speaker that way, but it does seem to work fine. The woofers though, aren't being driven any longer with the t-amp. Though, if doing any of this is causing damage, I'll stop.

[DougMac]

Thanks :)

I had thought the internal crossover would manage which frequencies it was fed from a full range amp
That is correct. I think your 25 watts might be ok to power the tweeter, but not a good idea for the woofers.

Was your tweeter in the HTM-200 that was damaged being driven by a T amp? As you pointed out, overdriving a modest powered amp can be as destructive to speakers as providing too much power.

Since you evidetently watch movies with action at loud volumes, I think using an underpowered amp for 340's is an overall bad idea. I'm not sure why you'd even be considering it, given your past experience.

[Mag_Neato]

Here's something I found thru a quick google search:

"The true benefits of bi-amping cannot be realized with passive crossover networks of a speaker system. Bi-amping truly shines when parts of the passive network of the speaker system is replaced by active networks where each amplifier is bandwith limited at the input. For more detailed information about bi-amping, we recommend reading the following article Benefits of Bi-Amping from Elliot Sound Products."

Sorry, the article link did not copy. Basically, it says to use 2 identical amps along with what it says above to achieve the best results. Maybe Dave F. can shed some more light on this. I do believe the speakers' crossover needs to be designed for bi-amping.

[choirbass]

That is correct. I think your 25 watts might be ok to power the tweeter, but not a good idea for the woofers.

Was your tweeter in the HTM-200 that was damaged being driven by a T amp? As you pointed out, overdriving a modest powered amp can be as destructive to speakers as providing too much power.

Since you evidetently watch movies with action at loud volumes, I think using an underpowered amp for 340's is an overall bad idea. I'm not sure why you'd even be considering it, given your past experience.

Yeah, I've been talking with Dave over the last few days after i damaged the 200 SE. (paraphrasing) He said had said that driving speakers with too little power, can cause the amp to clip at high enough levels, and that sends a surge to the speaker, which is what causes the distortion. I had looked online after that, and the clipping I guess is sending a constant sine wave to the driver(s), not allowing the coil to cool down, it overheats, and is damaged after long enough. (if i remember right).

The reasoning for multiple amps though, even if they are barely passing the minimum recommended wattage, was to lessen the load on each amp so they wouldn't clip. And you cant attach more than one set of wiring to the 200s like the 340s, and these t-amps arent bridged (so bridging the channels is out of the question), so I was hoping that it would be feasible with each t-amp channel driving the high/low. But, with barely enough wattage as it is, even multiple amps isnt going to really work it turns out anyhow.

[choirbass]

Here's something I found thru a quick google search:

"The true benefits of bi-amping cannot be realized with passive crossover networks of a speaker system. Bi-amping truly shines when parts of the passive network of the speaker system is replaced by active networks where each amplifier is bandwith limited at the input. For more detailed information about bi-amping, we recommend reading the following article Benefits of Bi-Amping from Elliot Sound Products."

Sorry, the article link did not copy. Basically, it says to use 2 identical amps along with what it says above to achieve the best results. Maybe Dave F. can shed some more light on this. I do believe the speakers' crossover needs to be designed for bi-amping.


Yeah, bi-amping non-identical amps really is a bad idea, can damage the speakers internals and what not, I did end up purchasing a total of 4 of the same t-amps to drive the 4 200's and 3 340s, and then when it all ended up not working out, I thought possibly using them to bi-amp might work, instead of not being able to use them at all, kinda a waste of ~$350 in amps if i wasnt able to at least put them to some use, lol.

I didn't realize at the time when i purchased them that too little wattage could really be a bad thing, so didn't think much of it, unfortunately.

[Funambulistic]

Oh, what a can of worms we can open with this discussion! Basically, from my experience (both academic and practical) any loudspeaker with two sets of binding posts (most often supplied with the ubiquitous jumpers) can be bi-wired or bi-amped (said jumpers removed, of course). Most proponents say bi-wiring is better than not and bi-amping is even more desirable. Of course, possibly the best way to go (as your referenced article mentioned, Ed) is to crossover the amplifiers themselves so that they do not have to run “full range” and, in turn, feed their bandwidth restricted signal to a speaker component (woofer, midrange and tweeter – tri-amping!) without its own crossover. Those “Akitv” (to borrow a term from Linn) systems are rather rare. I once had the pleasure of listening to a pair of the original B&W Nautilus speakers and they required six :eek: mono blocks to realize their full potential. I, for one, like the idea of a single pair of binding posts, something that Ascend employs with the Sierra-1s, as does Wilson Audio, Dynaudio and Sonus Faber, to name a few. Kind of a “You feed us the signal, we’ve got the rest covered” mentality.

Then there are the snake oil vendors… On a harmless note, I visited an audio shoppe where the practice was to single wire a bi-wireable speaker with the positive lead going to the woofer’s positive binding post and the negative to the tweeter’s negative (with jumpers in place). When I asked why they did this, they told me a rep from Linn (or maybe it was Naim) suggested it because it sounded better. I asked for a demonstration and could not discern a difference (perhaps my ears are not audiophile approved). I am sure it made some people feel better, though… :p

@Brandon: Did you say you were bi-amping with 25 watts (i.e. 50 watts total to each speaker) or bi-wiring? I guess I am a little confused as to what your intentions were. And DougMac is quite correct: it is much easier to blow a speaker from lack of power (the amp clipping) than too much power. I learned this the hard way… ;)

[Funambulistic]

Sorry, Brandon - I just saw your last posts (I was typing at the time). Please disregard my question... And my comments about wattage...

[choirbass]

@Brandon: Did you say you were bi-amping with 25 watts (i.e. 50 watts total to each speaker) or bi-wiring? I guess I am a little confused as to what your intentions were. And DougMac is quite correct: it is much easier to blow a speaker from lack of power (the amp clipping) than too much power. I learned this the hard way… ;)

Well, since each t-amp comes with 2 amps (L+R), I was hoping that the 50w from a single t-amp would be enough to avoid problems (with a 25w amp from the L/ch driving the tweeter, and a 25w amp from R/ch driving the woofers).. though that only leaves 15w headroom total, which really doesn't sound like enough, especially without knowing how much power each driver really needs.

[choirbass]

That is correct. I think your 25 watts might be ok to power the tweeter, but not a good idea for the woofers.

Was your tweeter in the HTM-200 that was damaged being driven by a T amp? As you pointed out, overdriving a modest powered amp can be as destructive to speakers as providing too much power.

I had missed this, sorry. Yeah, the tweeter was damaged.


..hm, im just tired now since im completely misreading lol.. off to sleep.

[davef]

I have a 2 channel t-amp that is rated for 25w/ch, but know the 340's are rated for 35w minimum. Would 25w per post be enough to safely drive them without risking damage at all, even if they were driven loud?

I ask because a tweeter in an htm-200 se was damaged during a loud scene in LOTR, and didnt realize at the time that too little can actually be a really bad thing :(.


Thank you for any help,

Brandon

25 watts per speaker input (25 watts to the tweeter and 25 watts to the woofer) should be safe with regard to possible damage from clipping. In most cases, hard clipping will take out the tweeter only and leave the woofers OK. The woofers we use are extremely rugged and unless the T-amp goes to DC, they will be fine.

That being said, with 25 watts feeding the woofer section and 25 watts feeding the tweeter, you will lose headroom compared to just using a 50 watt amplifier. Reason for this is that the high-frequency content (what is being sent to the tweeter) will demand much less current than the low-frequency content being sent to the woofers. For example, with a 50 watt amp driving both the tweeter and woofer sections, 5 watts might be utilized by the tweeter and 45 watts will be available to the woofers.

By using two separate T-amps for what is called "passive bi-amping", there will be excess power available for the tweeter and not quite enough for the woofer section.

Having said that, passive bi-amping of the 340 SE is a MUCH better option than using a single 25w T-amp to drive them.

Hope this makes sense!

[choirbass]

25 watts per speaker input (25 watts to the tweeter and 25 watts to the woofer) should be safe with regard to possible damage from clipping. In most cases, hard clipping will take out the tweeter only and leave the woofers OK. The woofers we use are extremely rugged and unless the T-amp goes to DC, they will be fine.

That being said, with 25 watts feeding the woofer section and 25 watts feeding the tweeter, you will lose headroom compared to just using a 50 watt amplifier. Reason for this is that the high-frequency content (what is being sent to the tweeter) will demand much less current than the low-frequency content being sent to the woofers. For example, with a 50 watt amp driving both the tweeter and woofer sections, 5 watts might be utilized by the tweeter and 45 watts will be available to the woofers.

By using two separate T-amps for what is called "passive bi-amping", there will be excess power available for the tweeter and not quite enough for the woofer section.

Having said that, passive bi-amping of the 340 SE is a MUCH better option than using a single 25w T-amp to drive them.

Hope this makes sense!


Thanks Dave, that did clear up a lot :)

[GirgleMirt]

Which T-Amp do you have? I wasn't aware there was a 25W/ch T-Amp... :confused:

Also the T-Amps are usually rated for 4 ohms, if you run 340SEs, which are 8 ohms, the original Sonic Impact T-Amp for example was rated 15W (4 ohms), so you get something like 5-6W at 8 ohms... Even the Super T amp and the 2nd gen seem to share the same power output...

The boards (and other T-Amps by companies other than Sonic), seem to share the 25W rating @4 ohms, so again, running 8 ohms speakers you're getting less Watts... One for example says 25W @ 4ohms and 14W @ 8 ohms...

[choirbass]

Which T-Amp do you have? I wasn't aware there was a 25W/ch T-Amp... :confused:

Also the T-Amps are usually rated for 4 ohms, if you run 340SEs, which are 8 ohms, the original Sonic Impact T-Amp for example was rated 15W (4 ohms), so you get something like 5-6W at 8 ohms... Even the Super T amp and the 2nd gen seem to share the same power output...

The boards (and other T-Amps by companies other than Sonic), seem to share the 25W rating @4 ohms, so again, running 8 ohms speakers you're getting less Watts... One for example says 25W @ 4ohms and 14W @ 8 ohms...

That is something I 'completely' missed, lol :o... The Topping TP21 is only 25w@4ohms now that I reread the specs on the manufacturers site:

http://www.p-macaudio.com/ProductDetails.asp?ProductCode=TP21

On the plus side, I definitely learned a few things in a relatively short time, and can certainly look towards investing in a different set of suitable amps now :)

[DougMac]

On the plus side, I definitely learned a few things in a relatively short time, and can certainly look towards investing in a different set of suitable amps now :)
I've got just what you need:

http://www.mcintoshlabs.com//images/products/mc452-s-front.jpg

[choirbass]

I've got just what you need:

http://www.mcintoshlabs.com//images/products/mc452-s-front.jpg

:p I could see that more happening if I did have more money, lol. Buuuut, looking on their site, you can't even buy them online, so no price. Hm. I guess the old saying 'If you have to ask, you probably can't afford it' applies :).

But, I will be looking around more, even if buying something isn't going to happen 'all' that soon.

[Funambulistic]

It runs a mere $7000. Pocket change, my dear fellow... If you really want to get serious, the MC1.2kW monoblocks at $11,000 each are the way to go. So, for a 7.1 system it would be... um, I suck at math - where's my checkbook? ;)

[buddhadas]

There is always used McIntosh.

The bottom shelf is a Mc 2120, this does the trick rather well. :D

Jim

[buddhadas]

Or this for stereo with the Sierra's. None of these amps will break the bank, thankfully.

[choirbass]

What about an Emotiva UPA-7? http://emotiva.com/upa7.shtm.. $600 isnt bad at all. Either that or just going the mono route... but would definitely take longer that way, not that I'm on a deadline or anything, lol. Emotiva came to mind only because of the looks, don't know much about them beyond that.

I probably will look into McIntosh, since it's been mentioned a few times, or maybe Marantz even?

[Funambulistic]

I was looking on Audiogon for multi-channel amps for you (I love spending other people's money ;) ) and saw an Emotiva amp that sold... just now. Everything I have read about Emotiva, especially their amps, has been good. $125 watt x 7 for $600? You can't do much better than that. The build quality is excellent and they look gorgeous. Granted, they are not McIntosh... But neither is the price.

[buddhadas]

That is why I suggested used McIntosh. To afford the new ones I would have sell my soul, since I have already sold my soul for rock-n-roll that is no longer an option. :D

[choirbass]

Emotiva it is :D. Birthday is coming up in a few days, and I have that much set aside as well. Still need to finalize shipping with Dave too. But, that should be taken care of soon I would think. Then, all should be good :).

[choirbass]

That is why I suggested used McIntosh. To afford the new ones I would have sell my soul, since I have already sold my soul for rock-n-roll that is no longer an option. :D

I guess I was just a bit unsure as far as used. With a warranty being out too, probably.

[Sam1000]

I guess I was just a bit unsure as far as used. With a warranty being out too, probably.

BTW. the 340s sound fantastic with a used H/K receiver as well :-)