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Author Topic: They keep making the same errors  (Read 7408 times)

Hal Bissinger/COMSYSTEC

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Re: They keep making the same errors
« Reply #10 on: March 27, 2013, 11:30:24 pm »

Well, if you are talking about those eight 15w/100v speakers in your other post they were close. Total would be 8.33 ohms.
 
Could you use one channel of a 400w per channel consumer amp? You could try. Many won't play nice with inductive loads though and most power ratings are fantasy. 
 
-Hal
« Last Edit: March 27, 2013, 11:33:18 pm by Hal Bissinger/COMSYSTEC »
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BenGibbs

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Re: They keep making the same errors
« Reply #11 on: March 30, 2013, 07:53:11 pm »

Well, if you are talking about those eight 15w/100v speakers in your other post they were close. Total would be 8.33 ohms.
 
Could you use one channel of a 400w per channel consumer amp? You could try. Many won't play nice with inductive loads though and most power ratings are fantasy. 
 
-Hal


Lucky I didn't say anything. I was under the impression the total impedance would be in the order of 50 ohms +.
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Mike Caldwell

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Re: They keep making the same errors
« Reply #12 on: March 30, 2013, 08:39:36 pm »

I could make a huge list but I'll keep it short.

One of my favorites is the spec for a cassette tape recorder as only recording format in school music rooms and auditoriums. I will say that one has started shifting to CD recorders but only in the last couple years but the cassette still shows up from time to time. You gotta love copy and paste engineering from 20 year old specs putting our tax dollars to good work.

Another is the spec for all the audio equipment in the rack to have the chassis bonded to a common ground buss bar isolated from the rack and the buss bar tied to the common ground point in the telcom server room. Yea rack was wired to "spec" and it hummed like no tomorrow till the buss bar grounding was removed. Maybe in a AM transmitter site something like would have to be worked out and implemented.

« Last Edit: March 30, 2013, 11:20:52 pm by Mike Caldwell »
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duane massey

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Re: They keep making the same errors
« Reply #13 on: March 30, 2013, 11:06:10 pm »

I'm very glad to be removed from dealing with consultants and designers. One of the worst ones I can recall involved a consultant who loved Lyntech power control systems, showed up on every job.
He spec'd a complete breaker panel, but with only ONE breaker in it. The system consisted of ONE TOA powered mixer and 12 70v speakers tapped at 5w each. The client never even questioned the expense.
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Duane Massey
Technician, musician, stubborn old guy
Houston, Texas

Ron Hebbard

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Re: They keep making the same errors
« Reply #14 on: March 31, 2013, 12:56:02 am »

I'm very glad to be removed from dealing with consultants and designers. One of the worst ones I can recall involved a consultant who loved Lyntech power control systems, showed up on every job.
He spec'd a complete breaker panel, but with only ONE breaker in it. The system consisted of ONE TOA powered mixer and 12 70v speakers tapped at 5w each. The client never even questioned the expense.

Tell me the only breaker was the one powering the sequencer and you'll have me convulsing!

Toodleoo!
Ron Hebbard
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Jason Lavoie

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Re: They keep making the same errors
« Reply #15 on: April 01, 2013, 10:40:29 am »

Well, if you are talking about those eight 15w/100v speakers in your other post they were close. Total would be 8.33 ohms.
 
Could you use one channel of a 400w per channel consumer amp? You could try. Many won't play nice with inductive loads though and most power ratings are fantasy. 
 
-Hal

I think you missed a zero there.. and went 70V instead of 100V
150W@70V gives 8.33 ohms.
15W@100V gives 166 ohms

Jason
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Brad Weber

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Re: They keep making the same errors
« Reply #16 on: April 01, 2013, 12:30:39 pm »

I'm very glad to be removed from dealing with consultants and designers.
The problem is not consultants and designers.  The problem is processes and situations that support or even favor unqualified Consultants and Designers.  This often manifests itself in public bids and large corporate bids with a "low qualified bid" approach as the 'qualified' aspect often relates more to business rather than technical qualifications.

Adding to that, while groups like the Construction Specifications Institute have tried to reinforce that communications systems are a separate work product, many Owners, Purchasing Agents, General Contractors, Construction managers and so on still include AVL work under the Electrical Engineer and Electrical Contractor.  When those parties are having to bid competitively to get their work then that almost forces them to cut corners where they can including things like using 'free' design services, regurgitating old documents, etc. because if they don't do that then the project may go to the competitor that did.

A similar situation exists with internal resources being asked to bid systems, they will often take the path of lowest cost/least effort, especially if they are not the ones who have to live with the results.

This topic always reminds me of the State bid where the actual End User had been burned before and worked with me to make sure we qualified the bidders.  At the public bid opening the Apparent Low Bid was significantly deficient on some of the qualifications and their bid was about to be rejected when the State Purchasing Agent, who knew nothing about audio or the actual work involved in general, stood up and said they could accept any discrepancies they wanted and would accept the low bid.  Basically, that person didn't seem to care about anything other than being able to go back to their superiors to tell them how much money they supposedly saved  (and regardless of whether it actually represented getting a lesser value).  It took the End Users actively fighting it and getting Attorneys and higher ups at the State involved to finally get a determination that the qualifications were reasonable and that bid was non-responsive.  When the process supports or even promotes cutting corners and incompetence, its a challenge to try to change that.
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Ivan Beaver

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Re: They keep making the same errors
« Reply #17 on: April 01, 2013, 01:03:01 pm »

I think you missed a zero there.. and went 70V instead of 100V
150W@70V gives 8.33 ohms.
15W@100V gives 166 ohms

Jason
Actually a 70.7V line at 8 ohms is 624 watts-not 150.

We are not talking peak power here-but rather continuous.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Alan Clayton

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Re: They keep making the same errors
« Reply #18 on: April 09, 2013, 10:16:22 am »

Much more common than some might expect and not always unintentional.  One company around here had a reputation for years if not decades for offering free 'design services' to Owners and Electrical Engineers through which they would generate documents that were so incomplete and filled with so many errors and vague references that it discouraged anyone else from bidding.  And if they did have to compete then that allowed them to interpret the documents however it benefited them.  As long as Owners and Engineers accepted that they continued to work that way.

I have a local competitor that does that, except it's just with the engineers. Owners tend to hate them. 

For instance you will see things like Provide Sennheiser SM58 microphones or QSC CT series amplifiers.....

If they get the job, the engineers rubber stamp it. If I get the job, the engineer takes my submittable to my competitor who goes over it with a find toothed comb and nit picks any little discrepancy, or points to the clause that says "you have to make it work!"

Just found another one "Acceptable Speaker shall be Atlas Soundtube RS800i -series"
« Last Edit: April 09, 2013, 05:02:27 pm by Alan Clayton »
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ProSoundWeb Community

Re: They keep making the same errors
« Reply #18 on: April 09, 2013, 10:16:22 am »


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