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Author Topic: Spa/Retail Install - Distortion as I add speakers?  (Read 545 times)

Paul Shearer

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Spa/Retail Install - Distortion as I add speakers?
« on: February 27, 2020, 03:16:54 pm »

Hi all! I am installing a 70v setup in my wife's spa and I am coming up against an odd issue where there is distortion in the audio that becomes present as I add speakers. Here are the deatails:

Amp: Pyle 300w 70v Amp - https://www.amazon.com/Wireless-Bluetooth-Public-Address-Amplifier/dp/B07MTXN7Q9/ref=sr_1_14?keywords=pyle+bluetooth+amp&qid=1582841525&sr=8-14 Edit: I originally linked the incorrect amp. Apologies.
Speakers: Speco 8" 15w https://www.bhphotovideo.com/c/product/1246235-REG/speco_technologies_86_series_g86tg_70_25v.html - these were already installed.

I have 8 of these installed in a drop ceiling, and they are wired in parallel. As soon as I add more than 1 to the wiring, I can start to hear some distortion in the audio signal. This is a spa so the audio level is VERY low. I am barely pushing them at all. In fact, I would say the volume knob on the amp is at roughly 5%.

I am a former touring musician so I have some experience with pro music audio, but this install has been giving me some issues!

So far I have tried:
- changing out speakers (still distorted)
- changing out to a lower wattage Pyle amp (still distorted)
- removing all but 1 speaker from the chain (no distortion)
- replacing the wiring (still distorted)
- using different wattage taps on the transformer (still distorted)

Any ideas? Thanks!!! :)
« Last Edit: February 27, 2020, 05:13:27 pm by Paul Shearer »
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Brian Jojade

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Re: Spa/Retail Install - Distortion as I add speakers?
« Reply #1 on: February 27, 2020, 04:34:57 pm »

The amp you have linked is NOT a 70v amp.  You should use a step up transformer such as https://www.parts-express.com/70v-200w-high-power-speaker-line-matching-transformer--300-226. This transformer would present an 4 ohm load to the amp and then you simply add up how many watts you're tapping of speakers and make sure you don't go over 200 watts. If you're running stereo, you'd need 2 of these, one for each channel.

Or, a better solution is get a quality amp that does have 70v output capabilities built in.  The Pyle amp you are using is a pile of you know what.... The specs listed are all over the board.  The rated distortion is pretty high, even on a good day. :)
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Brian Jojade

Paul Shearer

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Re: Spa/Retail Install - Distortion as I add speakers?
« Reply #2 on: February 27, 2020, 05:14:54 pm »

The amp you have linked is NOT a 70v amp.  You should use a step up transformer such as https://www.parts-express.com/70v-200w-high-power-speaker-line-matching-transformer--300-226. This transformer would present an 4 ohm load to the amp and then you simply add up how many watts you're tapping of speakers and make sure you don't go over 200 watts. If you're running stereo, you'd need 2 of these, one for each channel.

Or, a better solution is get a quality amp that does have 70v output capabilities built in.  The Pyle amp you are using is a pile of you know what.... The specs listed are all over the board.  The rated distortion is pretty high, even on a good day. :)

Hey Brian! Thanks for the reply. I originally linked the wrong amp.

The correct one is here: https://www.amazon.com/Wireless-Bluetooth-Public-Address-Amplifier/dp/B07MTXN7Q9/ref=sr_1_14?keywords=pyle+bluetooth+amp&qid=1582841525&sr=8-14

I am not surprised it is low quality, do you have any decent budget recommendations?
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Caleb Dueck

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Re: Spa/Retail Install - Distortion as I add speakers?
« Reply #3 on: February 27, 2020, 06:59:17 pm »

Hey Brian! Thanks for the reply. I originally linked the wrong amp.

The correct one is here: https://www.amazon.com/Wireless-Bluetooth-Public-Address-Amplifier/dp/B07MTXN7Q9/ref=sr_1_14?keywords=pyle+bluetooth+amp&qid=1582841525&sr=8-14

I am not surprised it is low quality, do you have any decent budget recommendations?

Define 'budget'.  Nothing is going to be in the uber-nowhere-near-reality price point of a Pyle item.  You get what you pay for is totally true.  If having background music doesn't help business more than a handful of dollars a year - something's wrong.  :) 

Here's low cost but not junk-
QSC SPA series
Powersoft Mezzo
Stewart
LEA
RDL
Lab.Gruppen Lucia

Make sure you add up the wattage of all the speakers, and add around 20% extra.  If you have 12x 15w speakers - plan on a 225w per channel amplifier.  Make sure it's rated at 70V, not 2/4/8 ohm or 100V.  You will also want some sort of mixer/DSP/processing in the amp or upstream; use a good high pass filter around 100Hz to keep the transformers from distorting. 

Lab Gruppen Lucia 240/1-70 if you have 13 or fewer speakers tapped at 15w, or 19 or fewer speakers tapped at 10w.  Has built-in basic DSP.  This is what I'd look at first for low cost but not awful quality.  Slightly under $400. 

Personally I'd look at something with a bit more power and DSP.  That way when you rip out the Speco speakers for something listenable - you won't have to spend money yet again on an amplifier. 
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Brian Jojade

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Re: Spa/Retail Install - Distortion as I add speakers?
« Reply #4 on: February 27, 2020, 07:22:53 pm »

The specs on that unit are even uglier.  Advertised THD at 1%  Yikes! Most amps you'll see listed at .05% or less distortion.  But you're dealing with a $65 amp.  Don't have any expectations of quality out of that.  Yeah, they say that it's a 500 watt amp, but they say 'MAX' That's a far cry from the RMS rating that any reputable manufacturer would use.  Peak power is what you get when all hell freezes over. Real RMS power can be a fraction of that.

Do you have a realistic budget to work with on this? If you're driving 8 speakers tapped at 15 watts per speaker, that means you need an amp capable of 120 watts or more.  For ceiling speakers in an office setting, 15 watts is pretty high, actually.  You could probably roll them back to 10 watt or even 5 watt taps and have them do the job.

A nice matching amp that I'd consider is the JBL CSA 1120Z. 120 watt amp, designed to give you years of reliable service without the gimicky crap on the toy amps.  However, the MAP on this unit is $419.  That's pretty much at the lowest end of what would be considered decent quality.  Quality 70v amps are designed to give you decades of reliable service, so over the life of it, it's not that expensive.

Alternatively, you can use standard amps and use your own matching transformer which I linked earlier. Note that just the matching transformer costs nearly what your amp does.  That should be an indicator of what you're working with....

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Brian Jojade

Gordon Brinton

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Re: Spa/Retail Install - Distortion as I add speakers?
« Reply #5 on: February 27, 2020, 10:44:09 pm »

Are you certain you have things hooked up correctly?

You are using the 70V terminal on the amp as (+) and the Com as (-). Since it is a 500 W amp, (we're probably talking 50 to 150 rms,) you can use the 5 W lead from each speaker transformer for (+) and the Com lead for (-). All 8 speakers together should then draw 40 W total. I wouldn't think that should be too much for that amp. All speakers should be wired parallel from that one 70V out terminal.
« Last Edit: February 27, 2020, 10:56:45 pm by Gordon Brinton »
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MikeHarris

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Re: Spa/Retail Install - Distortion as I add speakers?
« Reply #6 on: February 28, 2020, 01:57:08 am »

See if you can find a Denon DN-333XAB.
Now discontinued...but perfect

https://www.bhphotovideo.com/c/product/1135433-REG/denon_dn_333xab_mixer_amplifier_with.html
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MikeHarris

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Re: Spa/Retail Install - Distortion as I add speakers?
« Reply #7 on: February 28, 2020, 01:58:25 am »

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Paul Shearer

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Re: Spa/Retail Install - Distortion as I add speakers?
« Reply #8 on: February 28, 2020, 10:19:29 am »

The specs on that unit are even uglier.  Advertised THD at 1%  Yikes! Most amps you'll see listed at .05% or less distortion.  But you're dealing with a $65 amp.  Don't have any expectations of quality out of that.  Yeah, they say that it's a 500 watt amp, but they say 'MAX' That's a far cry from the RMS rating that any reputable manufacturer would use.  Peak power is what you get when all hell freezes over. Real RMS power can be a fraction of that.

Do you have a realistic budget to work with on this? If you're driving 8 speakers tapped at 15 watts per speaker, that means you need an amp capable of 120 watts or more.  For ceiling speakers in an office setting, 15 watts is pretty high, actually.  You could probably roll them back to 10 watt or even 5 watt taps and have them do the job.

A nice matching amp that I'd consider is the JBL CSA 1120Z. 120 watt amp, designed to give you years of reliable service without the gimicky crap on the toy amps.  However, the MAP on this unit is $419.  That's pretty much at the lowest end of what would be considered decent quality.  Quality 70v amps are designed to give you decades of reliable service, so over the life of it, it's not that expensive.

Alternatively, you can use standard amps and use your own matching transformer which I linked earlier. Note that just the matching transformer costs nearly what your amp does.  That should be an indicator of what you're working with....

Thanks, Brian and everyone else for your replies. I will get on replacing the amp ASAP, and report back if the distortion still persists.

MANY THANKS!!!!  ;D
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Re: Spa/Retail Install - Distortion as I add speakers?
« Reply #8 on: February 28, 2020, 10:19:29 am »


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