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Ianblumenfeld View Drop Down
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Points: 50 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Ianblumenfeld Quote  Post ReplyReply Direct Link To This Post Posted: 18 September 2020 at 11:26am
i don't wish to quote his name, we fell out...

surely if the gain is different, the phase will be shifted betwen same makes of different wattages???

sorry, i didn't just mean mid/tops,  i meant any drive unit

i seem...to recall doug self said absolute phase didn't matter

and surely, you don't know what all these electronics are doing to your phase from mixer to speakers???

whatever the case, if you listen domestically, it can never be possibly to reproduce the recording exactly as was produced in the studio.

different equipment and rooms....

i don't know everything, just a good bit of insight, too much to know


Edited by Ianblumenfeld - 18 September 2020 at 11:35am
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kipman725 View Drop Down
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Points: 231 		Post Options Post Options   Thanks (1) Thanks(1)   Quote kipman725 Quote  Post ReplyReply Direct Link To This Post Posted: 18 September 2020 at 11:42am
If the gain is different then this needs to be taken into account either by adjusting the input attenuators or in the crossover, it has no effect on the phase shift of the amplifier in the audio bandwidth.
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madboffin View Drop Down
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Points: 1539 		Post Options Post Options   Thanks (0) Thanks(0)   Quote madboffin Quote  Post ReplyReply Direct Link To This Post Posted: 18 September 2020 at 8:40pm
There's a difference between absolute phase (is the kick drum sucking or blowing) and relative phase or polarity (are all your amplifiers pushing and pulling together at all frequencies). It is generally thought that absolute phase doesn't really matter except in some very specific circumstances.
But you *definitely* need to keep track of relative phase when mixing and matching amplifiers.

Back in the day I used to build festival systems by combining rigs from several major hire companies. Some Crest, some Crown, it took a lot of careful management!
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Sonic the hedge View Drop Down
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Points: 161 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic the hedge Quote  Post ReplyReply Direct Link To This Post Posted: 18 September 2020 at 10:48pm
Originally posted by madboffin madboffin wrote:

There's a difference between absolute phase (is the kick drum sucking or blowing) and relative phase or polarity (are all your amplifiers pushing and pulling together at all frequencies). It is generally thought that absolute phase doesn't really matter except in some very specific circumstances.

Put like that, to my mind relative phase (polarity) is obviously the priority cos it will leave big gaps/cancellations if uncorrected, plus it's fairly easy to detect and simple to correct, just using your ears and swapping some wires around. 

Absolute phase would be more of a fine tuning thing to do with clarity, especially around the crossover regions. It's more difficult to detect and align, but I think over time folks have become more interested in tweaking, because we have plenty cheap tools available now to measure and correct. So not absolutely necessary, but if you can, why not?!!!

All IMO of course Tongue
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Semtek_soundsystem View Drop Down
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Points: 11 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Semtek_soundsystem Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2020 at 9:01am
Can't believe no one has suggested the ta-2400 from thomann, cheap as chips with 3 year warranty, theres a reason there are so many manufacturer variants of the same amp,  I've got 3 powering 6 usbs and absolutely spank them on every outing and theyve never let me down, most big name amps hold their value and will be out of your budget
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Earplug View Drop Down
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Points: 7216 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2020 at 9:52am
"oh by the way, and old dog told me not to mix amps on mid and tops, etc. and there is a phase difference, even with different powers of the same amp"

"surely if the gain is different, the phase will be shifted betwen same makes of different wattages???"


No - I have never seen any amp introduce a phase shift. It is not an issue. The issue could be the gain stucture of the amp - different amps will have different voltage gains, which could be a problem when mixing them in the same rack - or the fact that some (old) amps may have PIN 3 hot, rather than the more normal PIN2 (eg. old Crests).

AND yes - a lot of the (cheaper) Class D's do invert the polarity of the signal, ie, the "Positive", or "Red" output is actually "pulling" not pushing.
Earplugs Are For Wimps!
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Bams View Drop Down
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Points: 628 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Bams Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2020 at 11:38am
As mentioned in another thread. Echoes of a former member of this forum can be heard..
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kipman725 View Drop Down
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Points: 231 		Post Options Post Options   Thanks (0) Thanks(0)   Quote kipman725 Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2020 at 12:16pm
there is also the TSA-4300 which would make a good amp for tops:

the 4*300W rating is very much a worse case:

Single Channel

1x8Ω - 475W @1khz
1x4Ω - 682W @1khz
1x2Ω - 278W @1khz

 

Dual Channel

2x8Ω - 2x450W @1khz
2x4Ω - 2x698W @1khz
2x2Ω - 2x237W @1khz

 

Quad Channel

4x8Ω - 4x392W @1khz
4x4Ω - 4x594W @1khz

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levyte357- View Drop Down
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Points: 8128 		Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357- Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2020 at 12:25pm

Global Depopulation - Alive and Killing.
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Earplug View Drop Down
Old Croc
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Joined: 03 January 2012
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Points: 7216 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2020 at 2:35pm
Originally posted by Bams Bams wrote:

As mentioned in another thread. Echoes of a former member of this forum can be heard..


Yes, but at least we aren't seeing any stupid - or dangerous - "projects" being posted now...   Confused
Earplugs Are For Wimps!
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JonB67 View Drop Down
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Joined: 22 April 2016
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Points: 1376 		Post Options Post Options   Thanks (0) Thanks(0)   Quote JonB67 Quote  Post ReplyReply Direct Link To This Post Posted: 19 September 2020 at 7:15pm
Yet. 
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Mikkel View Drop Down
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Points: 549 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Mikkel Quote  Post ReplyReply Direct Link To This Post Posted: 20 September 2020 at 1:33pm
Originally posted by levyte357- levyte357- wrote:




Maybe, but getting the best bang for your buck is, and that comes in many different forms depending on your budget. There are other philosophies than just your own!!!
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