Distributed Audio Systems

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Indeterminacy
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Distributed Audio Systems

Post by Indeterminacy »

Practicalities in converting a DAS into a "regular" power amp.

I spent the better part of an hour explaining, to a guitar player, why you can't just hook up 2 speaker cabinets to a distribution amplifier. The concept of each speaker having it's own transformer and WHY could not cut through the target fixation fog of 200watts
per channel of brutalz potential. The word " Industrial" must mean extra stuff, right?

I recommended that Yngwie not just hook his cabinets to this amp he was gifted. I suspect he will anyway.

Is he is going to be disappointed in the result(s)?
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Re: Distributed Audio Systems

Post by crochambeau »

Depends on the amp I think, and exactly how it is utilized. I have a few industrial amps and I do use them "inappropriately".

My Rauland TAX125 amps operate fine with an 8 ohm load hanging on the 25 volt rail (I'm not forcing the amp into a severe mismatch). These are solid state, output transformer amplifiers.

I would avoid going for the gold by driving off the 75 volt line, unless the load reflects a power dissipation in line with the amplifier spec (using an "assumed" constant voltage as the baseline of the equation).

I've seen plenty of old PA amps (tubed now) that have taps for distribution or direct, and I want to say some (if not all) of them do a little sharing down in the lower end of the ratio turns on the secondary.

I say let the kids play in the street all they want.
When in doubt, add resistance.

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Re: Distributed Audio Systems

Post by Indeterminacy »

crochambeau wrote: Sun Nov 08, 2020 9:13 am Depends on the amp I think, and exactly how it is utilized.
My advice was based on unknown unknowns. I tend to err on the far side of caution when presented with applications based on something not in hand or no documentation.

Especially when Yngwie cooked 2 Greenbacks loaded in a 2-12" cab when he hooked it up to a Marshall JCM 800 - 100 watt head.
crochambeau wrote: Sun Nov 08, 2020 9:13 am I say let the kids play in the street all they want.
Agreed, but Yngwie.


I have yet to do the deep due diligence dive on the amp, shown below, in question.

Peavey ICA 400  3.jpg
Peavey ICA 400.jpg
Peavey ICA 400  2.jpg
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Re: Distributed Audio Systems

Post by crochambeau »

Indeterminacy wrote: Mon Nov 09, 2020 3:20 am
I have yet to do the deep due diligence dive on the amp, shown below, in question.

Image
Peavey. I would not at all be surprised to see them engineer out the output transformer element, which does complicate things. Can we get a gutshot?

My sense is that you'll see an "underbuilt" output section of discrete power devices, high power rails with low current throughput built in.

200 watts from 70 volts returns a 24.5 ohm load, so if Yngwie is happy stacking two 16 ohm cabs in series the current delivery capabilities of the amp will not be overshot.

But yeah, left to standard approaches you're probably looking at a future BBQ there.

Gutshot might tell a different tale, of course.

As an aside, if that 24 volt enable in feeds a solid state relay as opposed to a mechanical relay, it might be fun to feed it a signal derived comparator pulse to turn the amp on and off based on signal frequency. I got yer class C distortion secret right here, compadre.
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Re: Distributed Audio Systems

Post by Indeterminacy »

crochambeau wrote: Mon Nov 09, 2020 9:17 am
Indeterminacy wrote: Mon Nov 09, 2020 3:20 am
But yeah, left to standard approaches you're probably looking at a future BBQ there.

Yngwie is a name for a specific guitar player that frequents a local record store. He's actually a Punk/Hardcore, learned 3 chords, started a band guy, so Yngwie. Great dude, heart of gold. Artist. The "it kept blowing the fuse so I put one in it that wouldn't blow guy."

There was no way I could guide him to understand why it was not an all ya gotta do situation. Because output doesn't necessarily mean speaker. He could not grasp the concept. Completely brainlocked on, Dude - Industrial. Amplifier. 200watts per channel.

After smoking the legit, OG Greenbacks in a borrowed cabinet he said, " but it's a Marshall".

He will probably become a bandcamp millionaire.

When you stare into the Abyss, the Abyss stares back.


The one true Yngwie.
yngwie.jpg
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Re: Distributed Audio Systems

Post by crochambeau »

Indeterminacy wrote: Tue Nov 10, 2020 4:51 am After smoking the legit, OG Greenbacks in a borrowed cabinet
Oh man, ouch. Reminds me of the time I borrowed some vintage Altec mains and smoked those care of an overdriven amp. Expensive mistake. Ah youth.

Your stance in all of this appears quite sound. If that amp can be opened, and there is a 25 volt option (there really should be, since building code does not recognize 70 volt as a "low voltage" which puts constraints upon the people licensed to perform installations (at least in states that adhere to such concepts, I realize Peavey is a Mississippi company)) anyway, if it can be set to deliver a 25 volt rail he might fly under the radar in typical use.

Might.

I remember my palpable disappointment upon reading that the real Yngwie officially changed his middle name to Fucking, and then getting confirmation it was not true.
When in doubt, add resistance.

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