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Discussion Starter · #1 ·
Hi all!

I have a single 4Ω marine-grade speaker installed in a steam shower that I'm going to power from a separate amp so I can combine L/R on the pre-amp side.

The amp is listed as 4Ω in stereo mode -- but does that only apply if you have two speakers connected?

Would I have better success running more power in bridged mode even though the amp listed at 8Ω in bridged mode? Should I look for a different amp?

Speaker: www jamesloudspeaker com /assets/productAttachment/63SA-7-Datasheet-12-2013.pdf

Freq Response 38-22kHz ± 3dB
Impedance 4 ohms
Sensitivity 85dB @ 2.83V / 1m
Power Req. 25-50 watts

Amp: Pyle PAMP1000 www pyleaudio com /sku/PAMP1000/Digital-Stereo-Power-Amplifier[/url]

Technical Specs:
Max Power Output: 160 Watt
RMS Power Output: 80 Watt x 2 @ 4 Ohm
Frequency Response: 10-50kHz (+/- 3dB)
S/N Ratio: 100dB
T.H.D.: 0.1%
Stereo Impedance: 4-16Ohm
Bridged Impedance: 8-16Ohm
Voltage Selector 110/220V, 50/60Hz
Replaceable Fuse: T4AL (110/120V), T2AL (220/240V)
 

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I would not try to run a 4 ohm speaker with a bridged amp rated only at 8 ohms.
 

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Hi all!

I have a single 4Ω marine-grade speaker installed in a steam shower that I'm going to power from a separate amp so I can combine L/R on the pre-amp side.

The amp is listed as 4Ω in stereo mode -- but does that only apply if you have two speakers connected?

Would I have better success running more power in bridged mode even though the amp listed at 8Ω in bridged mode? Should I look for a different amp?

Speaker: www jamesloudspeaker com /assets/productAttachment/63SA-7-Datasheet-12-2013.pdf

Freq Response 38-22kHz ± 3dB
Impedance 4 ohms
Sensitivity 85dB @ 2.83V / 1m
Power Req. 25-50 watts

Amp: Pyle PAMP1000 www pyleaudio com /sku/PAMP1000/Digital-Stereo-Power-Amplifier[/url]

Technical Specs:
Max Power Output: 160 Watt
RMS Power Output: 80 Watt x 2 @ 4 Ohm
Frequency Response: 10-50kHz (+/- 3dB)
S/N Ratio: 100dB
T.H.D.: 0.1%
Stereo Impedance: 4-16Ohm
Bridged Impedance: 8-16Ohm
Voltage Selector 110/220V, 50/60Hz
Replaceable Fuse: T4AL (110/120V), T2AL (220/240V)
Just use one channel of that amp to power it. Not so hard. Rated for 4 ohms.
 

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Agree with the other comments; just run it on one channel.
Also, don't just connect the L/R out of the preamp with a Y cable. Here's why.
 

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The protection circuit on some amps kicks in if you don't have anything connected to them and you turn up the volume. So one channel connection may or may not work.

Also the nominal impedance given for a lot of speakers is a marketing number. It may or may not be 4 ohms in your case. If the amp has a protection circuit, then I would ignore such specs and connect and use the speaker anyway. Should it stress the amp too much, it will shut down. If there is no protection circuit (doubt it very much) then you need to make sure the amp doesn't run too hot. Touch the top of the case and if it is too hot to touch, then something is not right.

Enjoy your showers :).
 

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I kinda agree with amirm about just hooking up one channel and see what happens. I always thought you should have a load on a amp, but maybe that's old school thinking.

Also A9X-308's link on Y Cables was interesting. Made me think about using the ins and outs on my two subs instead of a Y, but it probably doesn't matter since that is a mono signal.
 

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The protection circuit on some amps kicks in if you don't have anything connected to them and you turn up the volume. So one channel connection may or may not work.

Also the nominal impedance given for a lot of speakers is a marketing number. It may or may not be 4 ohms in your case. If the amp has a protection circuit, then I would ignore such specs and connect and use the speaker anyway. Should it stress the amp too much, it will shut down. If there is no protection circuit (doubt it very much) then you need to make sure the amp doesn't run too hot. Touch the top of the case and if it is too hot to touch, then something is not right.

Enjoy your showers :).
Hmmm...let's see...85dB/w/m...in a shower heads are usually about a half meter or so from the ceiling...so 91dB/1 watt...in a highly reflective "room"....I don't thing I see an issue here, not in the amp driving it, or the protection circuit, or a possible lower impedance somewhere in the spectrum, overheating (unless you run the water too hot). You will be running a fraction of a watt on average.
 

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Hmmm...let's see...85dB/w/m...in a shower heads are usually about a half meter or so from the ceiling...so 91dB/1 watt...in a highly reflective "room"....I don't thing I see an issue here, not in the amp driving it, or the protection circuit, or a possible lower impedance somewhere in the spectrum, overheating (unless you run the water too hot). You will be running a fraction of a watt on average.
With the sound of shower going it won't be a fraction of watt. But that doesn't matter. An unloaded amplifier may trigger the protection circuit for both channels. When and how it triggers this cannot be explained away with how loud you are playing. My point regarding overheating was a general one dealing with the question of if "4 ohm is OK on 8 ohm amp." The best way to know if it is or is not OK is to run it and check for temps or protection circuit kicking in.
 

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With the sound of shower going it won't be a fraction of watt. But that doesn't matter. An unloaded amplifier may trigger the protection circuit for both channels. When and how it triggers this cannot be explained away with how loud you are playing. My point regarding overheating was a general one dealing with the question of if "4 ohm is OK on 8 ohm amp." The best way to know if it is or is not OK is to run it and check for temps or protection circuit kicking in.
Ha. I figured I'd get "amirmed" with that one. See, the thing of it is, I've actually done that installation. Sure the shower sound is loud, but loud is also an absolute. Nobody expects 20dB s/n in a shower, but nobody also tollerates sound louder than 85dB very well either. So your theories are correct, but in practice it doesn't matter. It'll be a watt at most, less than that typically. The shower my client had didn't suffer from lack of audio volume, it had other issues, mostly plumbing and steam generator. And the amp was low power, nothing special. Worked just fine.
 

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Let me back into this another way. I know from experience that you can hold a normal conversation in a shower with the water on without raising your voice. And while the distance between the participants may be somewhat less than a typical conversation outside a shower, the voice spl isn't likely to be much above 75db spl. The conversation is unimpeded by the shower noise. This implies that speech from said speaker in the ceiling would also need to reach the ears at 75dB spl. And at the stated speaker sensitivity that would require a fraction of a watt.

I compiled the data to support the above statement experimentally enlisting a willing volunteer, and while actual conversation wasn't sustained at length, becoming secondary to other activities, sufficient data was collected to support my statements. For completeness, both a male and female voice were sampled.

I urge and recommend anyone to replicate the experiment for validation of the data. Yeah. That's the reason I'm going with.
 

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Ha. I figured I'd get "amirmed" with that one. See, the thing of it is, I've actually done that installation. Sure the shower sound is loud, but loud is also an absolute. Nobody expects 20dB s/n in a shower, but nobody also tollerates sound louder than 85dB very well either. So your theories are correct, but in practice it doesn't matter.
I spoke of no theory. What I explained had nothing to do with how loud you do or do not listen to music in a shower. OP asked if he should use one channel or both and I said using one channel may cause the amplifier protection circuit to kick in. How loud that volume is or is not, is not something you can determine in advance. Some amps never do it. Some will shut off pretty quickly. This is not a theory. It comes from testing countless amplifiers and understanding of their design.

It'll be a watt at most, less than that typically. The shower my client had didn't suffer from lack of audio volume, it had other issues, mostly plumbing and steam generator. And the amp was low power, nothing special. Worked just fine.
Again this has nothing to do with our discussion. If it did, it would be a moving target since you said this: "And at the stated speaker sensitivity that would require a fraction of a watt." A watt is not a fraction of a watt. And what your client thought was adequate is neither here, nor there. Every shower and every person is different.

And that amp working means nothing as far as others doing the same if you were indeed driving it with one channel and leaving the other fallow.
 

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I spoke of no theory. What I explained had nothing to do with how loud you do or do not listen to music in a shower. OP asked if he should use one channel or both and I said using one channel may cause the amplifier protection circuit to kick in.
Yes, an amp with a protection circuit that shuts down the amp when one channel is not loaded. A possibly valid, but rare and somewhat ridiculous design. Frankly, rather illogical, and not something I've ever seen, but if you say it exists, we can take it on faith I guess.
How loud that volume is or is not, is not something you can determine in advance. Some amps never do it. Some will shut off pretty quickly. This is not a theory. It comes from testing countless amplifiers and understanding of their design.
Are you suggesting that it's quite common for an amp to go into protection when driving a 4 ohm nominal load at just a few watts or less? Like this is something so common as to be concerned with?
Again this has nothing to do with our discussion. If it did, it would be a moving target since you said this: "And at the stated speaker sensitivity that would require a fraction of a watt." A watt is not a fraction of a watt. And what your client thought was adequate is neither here, nor there. Every shower and every person is different.
Yeah, like people in general differ by more than +/- 3dB....don't think so.
And that amp working means nothing as far as others doing the same if you were indeed driving it with one channel and leaving the other fallow.
Is this really a common problem? Funny I've never once run into it in like 40+ years. I must live a sheltered life.

I think if you put a speaker with a given sensitivity in a shower you should be able to take a pretty good guess on how much power it will need to satisfy a user, and take a pretty educated guess as to if an amp would be challenged by the situation or not.

You can reach for a specific set of conditions where the system would fail, but it may not server much purpose other than to highlight an unusual situation.
 

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Is this really a common problem?
No. But neither is someone hitting your car the moment you pull out of the driveway. Fact that it is not common is not of any significance when it happens to you :).

Funny I've never once run into it in like 40+ years. I must live a sheltered life.
I don't know what you have done for those 40 years. Clearly it is not designing and evaluating amplifiers day in and day out or you would have seen this happening to quite a few units. Speaking personally, here is a rather recent example. I was testing a few AVRs and processors, using just their pre-amp output (evaluating their DACs), leaving the amplifier without a load. One of them would routinely go into protection mode when used this way. And it would do so at different volume settings. Here are the units I tested:



We are talking Yamaha, Pioneer, Anthem, Onkyo. Not some brand and unit no one has heard of. Was I surprised that it did that? No. It is within its "rights" to complain when used without a load as that is not a design criteria. The unit is designed to drive a speaker, not sit there and do nothing.

I think if you put a speaker with a given sensitivity in a shower you should be able to take a pretty good guess on how much power it will need to satisfy a user, and take a pretty educated guess as to if an amp would be challenged by the situation or not.
I keep saying this has nothing to do with the discussion at hand yet you keep arguing it. Maybe you think the above activation is due to using too much power? If so, that assumption is wrong. The protection circuit is not kicking in because you are drawing too much power. After all, there is no load at all. It is doing so because it is seeing DC offset on the load terminals and this can happen at any volume level.

You can reach for a specific set of conditions where the system would fail, but it may not server much purpose other than to highlight an unusual situation.
Running an amplifier without load *is* an unusual situation. Expecting predictable performance when it is not part of the design criteria is a mistake. OP is asking about this unusual situation and seeking advice. He is not asking how loud to play music in a shower.
 

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I don't know what you have done for those 40 years. Clearly it is not designing and evaluating amplifiers day in and day out or you would have seen this happening to quite a few units.
Ouch. Nice devaluation of a lifetime career. Sure can't get enough of that.

No I don't test amps every day, but I can assure you, nothing I have ever or will ever design would be so badly misbehaved as to trigger a protection fault under no load. But maybe I need an 80 year career to "measure up".

And it's off to unsubscribe from the Alfa-amirm dominated thread.

Yet Again.
 

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Discussion Starter · #16 ·
Agree with the other comments; just run it on one channel.
Also, don't just connect the L/R out of the preamp with a Y cable.
Ah, that's a really good point. Can anyone recommend a mono mixer or off the shelf summing cable? My soldering is rusty and I'd rather just move forward.

Either that -- or a good amp with a mono switch? Most of the Pyle amps I've seen with any mono switches are PA amps which don't have the low-end range for the high-end speaker I'm starting to regret installing in this shower. :)
 

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Ah, that's a really good point. Can anyone recommend a mono mixer or off the shelf summing cable? My soldering is rusty and I'd rather just move forward.

Either that -- or a good amp with a mono switch? Most of the Pyle amps I've seen with any mono switches are PA amps which don't have the low-end range for the high-end speaker I'm starting to regret installing in this shower. :)
Get one of these: http://atlona.com/product/at-pa100-g2/

It is a class-d design so very efficient and doesn't generate heat. It is small. And has ability to be remote controlled. It has mono/stereo switch. It is designed to be hidden some place and forgotten which I think you would want in this situation.

May be hard to find in retail though. Did a search and found one on Amazon. It has the right model number but wrong picture: http://www.amazon.com/Atlona-Techno...F8&qid=1429882569&sr=8-1&keywords=AT-PA100-G2

BTW, nothing wrong with salvaging that speaker for your use :).
 

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Ouch. Nice devaluation of a lifetime career. Sure can't get enough of that.

No I don't test amps every day, but I can assure you, nothing I have ever or will ever design would be so badly misbehaved as to trigger a protection fault under no load. But maybe I need an 80 year career to "measure up".

And it's off to unsubscribe from the Alfa-amirm dominated thread.

Yet Again.
Not sure Amir was claiming to be chained to a lab bench for 80 years.:D

Here is one example of why an amp should go into protect mode if it has no load on its output.

I once connected a set of speakers at the opposite end of a house using a long spool of 4 conductor wire. It was the only wire I had conveniently available at the time that was long enough to span the distance. It was a temporary install, so after connecting the speakers in the 'speaker room' and then unrolling enough for the span I left the remainder of the wire on the spool (~15') and connected the amp in the 'amp room' to the dangling end of the wire from the inner spool (rather than cut the wire).

Then I powered up the system and when I got back to the 'speaker room' I discovered that one of the wires had become disconnected from its speaker somehow. Since I was all the way in the 'speaker room' at the time, I decided to just connect the wire live instead of traveling the length of the house twice more to shut off the amp, and twice more again to turn it back on again after fixing the connection.

Of course that spooled wire generated a huge inductive spike off the active output signal while I fumbled with the connection, and blew the output fuse on that channel (no protection circuit on this particular piece of vintage cr-- er, equipment). Fortunately the amp survived the spike but there is no guarantee it was still in the same pre-spike state and/or could survive any such spike it might see at its output in the future.

This scenario could exist in any system with an intermittent connection to a speaker through long cabling of unspecified configuration. If the connection is making and breaking at random, and the speaker/crossover/wire stores significant energy, all bets are off as to whether any given amp will survive the inductive spikes that result. In such scenario it makes perfect sense to detect open output and go into protect mode before the speaker connects and spikes the amp.

Regarding whether or not an amplifier protection circuit detects an open at the output, my preference is that it should do whatever it needs to in order to protect the amp and speaker regardless of any inconvenience.

Most of the Pyle amps I've seen with any mono switches are PA amps which don't have the low-end range for the high-end speaker I'm starting to regret installing in this shower. :)
Here I was feeling weird for having an old HTPC installed in my bathroom... with Boston Acoustics sat/sub speakers of course.

Tip: if you for any reason notice that the amp cannot handle an open output (IMO unlikely but possible) simply connect something like a 10Kohm resistor across its output. If that is too large resistance, make it smaller until the amp functions OK but keep the power dissipation in the resistor within its spec (assume the amp is driving fully clipped square waves and use [[Vpeak-to-peak/2]squared]/resistance to calculate the power) and don't let it ignite a fire anywhere with its heat.

This is probably just academic debate and purely silly to get all 'steamed up':rolleyes: about. The amp is going to work just fine for you. Relax.;):)
 
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