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DjLeco View Drop Down
Young Croc
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Joined: 21 April 2009
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Points: 811 		Direct Link To This Post Posted: 15 October 2010 at 12:28am
Originally posted by kedwardsleisure kedwardsleisure wrote:

Ok, back on track with the bigger stuff.

OHM EA2400



 
 
 
 
 
 
 
 
 
 
 
Bad choice of cooling,the middle of heatsink must be placed on the center of fan , to assure entirely airflow passing...Cry


Edited by DjLeco - 15 October 2010 at 12:31am
I'm A Stupid SMART Romanian...
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mystyca View Drop Down
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Points: 158 		Direct Link To This Post Posted: 15 October 2010 at 4:38pm
Can't see anything wrong with the cooling myself, It's cooling the heatsink and o/p transistors, not much is going to overheat in there!!
DJ
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andyamp View Drop Down
Old Croc
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Points: 2115 		Direct Link To This Post Posted: 15 October 2010 at 5:14pm
Bad choice of cooling,the middle of heatsink must be placed on the center of fan , to assure entirely airflow passing...
good choice of cooling
a wise man changes his mind a fool does not.
http://www.matrixamplification.com/
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ceharden View Drop Down
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Points: 11696 		Direct Link To This Post Posted: 15 October 2010 at 5:35pm
Just think about the thermal gradient on that too.  The end next to the fan will be nice and cool, the other end will be really toasty.

I can't understand why they've got so many output devices.  To need that many it must mean they're dissipating a lot of wasted power as heat.  Which means a very inefficient output stage.
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Big-G View Drop Down
Young Croc
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Points: 1141 		Direct Link To This Post Posted: 15 October 2010 at 7:37pm
Originally posted by mystyca mystyca wrote:

Originally posted by kedwardsleisure kedwardsleisure wrote:

Yes with Sanken drivers

This is a 3U case, toroid is full case depth, twin 120mm varispeed fans, branded electrolytics etc.
One of best chinese OEM efforts so far I've seen, even the bridge rectifier heatsinks have their own airpax thermal switches!





I admire OHM industries passion for High quality Pro gear, Think most DJ's, Band's, Club's  and the like should check out OHM before considering anything else especially QSC which has copied OHM's slogan 'Serious about sound' but QSC is Passionate about sound with an amp which looks like ALTO, TAPCO and BEHRINGER. this made me laugh - http://www.youtube.com/watch?v=RhFinhM0Qv0 - Trying to sell something she knows nothing about!! Lowest Failure Rate!! my uncles has gone wrong twice!! A price from.. well you know, gives a little more power than anyone else.... What a Load of garbage!!

What are you on about? I have been running qsc's for years, never had a failure, they are the most reliable amps i have ever owned, my RMX4050's barely get warm when driving sub into 2.66 ohms p/ch. Alto, Tapco and Bellringer have all copied the qsc amps and done a bad job of it too.
They know what is what but they don't know what is what they just strut what the .
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Young Croc
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Points: 1141 		Direct Link To This Post Posted: 15 October 2010 at 7:43pm
Originally posted by ceharden ceharden wrote:

The end next to the fan will be nice and cool, the other end will be really toasty.




Looks to me like 80% of the air going through the fans will just blast into the case, suppose the transformer will keep cool then.
They know what is what but they don't know what is what they just strut what the .
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kedwardsleisure View Drop Down
Old Croc
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Points: 4811 		Direct Link To This Post Posted: 15 October 2010 at 8:27pm
Those fans extract
Kevin

North Staffordshire
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Big-G View Drop Down
Young Croc
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Points: 1141 		Direct Link To This Post Posted: 15 October 2010 at 8:32pm
Thats even worse isn't it?
They know what is what but they don't know what is what they just strut what the .
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mystyca View Drop Down
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Points: 158 		Direct Link To This Post Posted: 15 October 2010 at 9:36pm
Could be worse.... could have no fans!!,
As I see it, It need's all those output devices (32 - 16 per channel) because it's a 2400w amp,
A QSC RMX2450 (for example) is half the power with half the output devices so you have two amp manufacturers two different amp designers same transistors used with the same idea you need a complimentary pair PNP 2sa1943 & NPN 2sc5200 per 150w
i:e:
4 x pnp,npn (150w) = 600w total of 8 o/p devices
8x pnp,npn (150w) = 1200w total of 16 o/p devices
16x pnp,npn (150w) = 2400w total of 32 o/p devices
according to OHM the reason is 'Many designers specify the transistor compliment by the maximum that can be wrung from each device, ignoring the fact that good behaviour is dependant upon transistor-die area and sufficient heat removal.', Most manufacturers have there propaganda garbage to try and sell there product, Overall.........It's not an Amplifier Debate..........More Internals Please Tongue
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Young Croc
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Points: 1141 		Direct Link To This Post Posted: 15 October 2010 at 9:42pm
Agreed, debate over, more internals please Big smile
They know what is what but they don't know what is what they just strut what the .
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audiomik View Drop Down
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Points: 2962 		Direct Link To This Post Posted: 15 October 2010 at 11:03pm
An old Mosfet Amp from the 1980's, currently in need of some repairs, built for Bass Charrington Pubs - Toby Sound amp TSR-450S, 'larger brother' of the TSR-150X earlier in this thread.
One Channel tested into 8ohms is 200watts output and the design rating is 2x 225watts into 4ohms.
View from the front before cleaning and repairs - a sort of 'before' pic:


Mik
Warning! May contain Nuts
plus springs, washers, screws, etc, etc.
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mystyca View Drop Down
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Points: 158 		Direct Link To This Post Posted: 15 October 2010 at 11:27pm
Eh Oh, Are those LCR cap's I see, Also Ugly Knobs!!! When ya get this going get rid of those knobs they do not do it any justice. look like something off a 70's twin deck or something yuk.
DJ
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