New to forum - Need help with amp problem

[Stephen Durost]

Hoping one of you audio experts can help. Here is my situation. I have an apartment with 4 pairs of speakers (flush mounted in-ceiling) in various rooms. I was looking for a simple solution to allow me to use my iphone, and airplay, to play music in the apartment over one or all of the zones. I found a potential solution from Griffin Technologies - it's essentially a small amp that is connected to an Apple airport express - you then pair your iphone with the airport express, music streams to the amp and to your speakers. In this case I have the output from the small amp (20 watts per channel) feeding into a passive 4-zone speaker selector. Now the problem - while I could connect, I kept getting dropouts with the sound - as if the music was being interrupted. After isolating the problem to the small amp, I realize that (a) the amp is not strong enough to power more than one set of speakers at a time without turning down the volume so low that its unusable; and (b) the speaker selector, even with the switches of 3 of the 4 zones turned off, must still draw more power from the amp than it can put out - so I still get the dropouts. When I connect one set of speakers to the small amp, it works fine. The speakers all have minimum power requirements of 10 watts per channel.

So.....the standard response would be "get a more powerful amp" - but in this case, I don't want to move away from the Griffin Twenty, as it works beautifully with my iphone/ipad. So I wondered if I could buy another amp, and connect it between the Griffin Twenty (the 20 watt amp) and the speaker selector, so that the power is boosted. Will this work? I realize I will lose some fidelity, but frankly I'm not focused as much on that as ease of use. Hope someone can help - I am not an audio expert.

Steve

 

[markw]

If that little amp works so beautifully, why are you posting this here?

Please note the wording from the Griffin amp from their web site: "Griffin's Twenty audio amplifier lets you play audio from iTunes and AirPlay-enabled apps to an existing set of speakers using your Airport Express and Apple's AirPlay wireless protocol."

That implies one set of speakers, not four.

Seriously, since you insist on that Griffin amp, simply get one amp for each pair of speakers.

And, no, you can't just connect one after he other to incrase power. Amps don't work that way.

Other solutions are possible but that little amp won't be part of the solution.

 

[Stephen Durost]

Please norte the wording from the Griffin amp from their web site: "Griffin's Twenty audio amplifier lets you play audio from iTunes and AirPlay-enabled apps to an existing set of speakers using your Airport Express and Apple's AirPlay wireless protocol."

That implies one set of speakers, not four.

Seriously, since you insist on that Griffin amp, simply get one amp for each pair of speakers.

And, no, you can't just connect one after he other to incrase power. Amps don't work that way.

Wow, thanks for the nice welcome to the forum!

To answer your question, I don't want to get four amps for each speaker because of the cost, and space this would take up.

Now, for other folks on this board who hopefully might be a bit more welcoming than MarkW - I am assuming that an amplifier does just what it's name implies - it amplifies a signal. So if I am getting a signal out of the Griffin amp which is not strong enough to power my speakers; and I take that signal and amplify it again, but this time with a more powerful amp; that I would end up with a signal that had enough power to drive more than one set of speakers (although I realize that the signal quality may be somewhat degraded). As I said, I'm not an audio expert, so perhaps what I suggest won't work, but rather than just reply "amps don't work that way", perhaps someone can just give me a civil explanation.

 

[crossedover]

Just get a speaker level to line level converter and add a small pro amp like the crown drive core 1500 to insert in between the Griffen and the speaker selector, since your set on the current gear

 

[slipperybidness]

Wow, thanks for the nice welcome to the forum!

To answer your question, I don't want to get four amps for each speaker because of the cost, and space this would take up.

Now, for other folks on this board who hopefully might be a bit more welcoming than MarkW - I am assuming that an amplifier does just what it's name implies - it amplifies a signal. So if I am getting a signal out of the Griffin amp which is not strong enough to power my speakers; and I take that signal and amplify it again, but this time with a more powerful amp; that I would end up with a signal that had enough power to drive more than one set of speakers (although I realize that the signal quality may be somewhat degraded). As I said, I'm not an audio expert, so perhaps what I suggest won't work, but rather than just reply "amps don't work that way", perhaps someone can just give me a civil explanation.

Amps are designed to take low-level signals (ie line level) and amplify them to high level signals (ie speaker level).

If you drive a 2nd amp from the (high level) output of the 1st amp...........you are probably looking at serious distortion/clipping on a good day, and possible fire on a bad day.

 

[Stephen Durost]

Just get a speaker level to line level converter and add a small pro amp like the crown drive core 1500 to insert in between the Griffen and the speaker selector, since your set on the current gear

Thanks, I appreciate the advice. This makes sense (thanks to Slipperbidness for explaining why you don't want to take an amplified signal and amplify it again), and will also be fairly inexpensive and unobtrusive.

 

[Stephen Durost]

Amps are designed to take low-level signals (ie line level) and amplify them to high level signals (ie speaker level).

If you drive a 2nd amp from the (high level) output of the 1st amp...........you are probably looking at serious distortion/clipping on a good day, and possible fire on a bad day.

Thanks for the explanation - nice to hear from more welcoming members on this forum.

 

[markw]

Well, when someone comes in and demands solutions that fit their uninformed, narrow, sphere of knowledge, they shoud be able to live with a sarcastic response.

Had you simply asked for a solution to your problem without stipulating how it should be done, your response would have been somewhat different.

 

[Jeff R.]

Well, when someone comes in and demands solutions that fit their uninformed, narrow, sphere of knowledge, they shoud be able to live with a sarcastic response.

Had you simply asked for a solution to your problem without stipulating how it should be done, your response would have been somewhat different.

I interpreted none of that when I read his post.....must have been a long day at work. There were no demand just questions about whether his uninformed idea would work. He never claimed to be an expert! He was trying to think out if the box for a solution and was asking for some knowledgeable feedback. I don't think it needed a kick in the nuts.

My only other thought on a solution was to buy a 2 channel stereo receiver with A/B channels and use it along with a speaker selector and you could the use the receiver either speaker selector to pick which speakers play. Might be tough to run all 8 at one time. The real challenge is we do not know how these speakers are wire?



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[TLS Guy]

Thanks, I appreciate the advice. This makes sense (thanks to Slipperbidness for explaining why you don't want to take an amplified signal and amplify it again), and will also be fairly inexpensive and unobtrusive.

Your real problem is not just power but driving too low an impedance for any amp. Your Griffin is rated at 8 ohms impedance. It uses the class D Tripath amp I have found out. So you are offering it a 2 ohm load when you connect all four zones. This will blow up most amps. For all I know your speakers my be four ohm in which case you would be offering your amp a one ohm load. You need to know the impedance of your speakers. You can get impedance matching speaker selectors which contain auto transformers.

The one I linked is cheap and cheerful, and I suspect the transformers are not of the best quality. The impedance matching can be defeated if you have impedance matching controls in each room. You would need to be careful you did not accidentally defeat it. You will have a little power loss and your amp is lean for driving four rooms at once. When you do that with this device you will have a little under 5 watts per channel in each room. This device will handle 70 watts per channel, which would give you about 17 watts per channel in each room, which is not a big increase. If you need more power, your best bet is a distribution amp, that would have 8 amps in one case.