mosfet power amplifier in 1U or in 2U rack chassis

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ppa

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I have designed a stereo mosfet power amp of 100W/8ohm and 180W/4ohm of power that can be mounted on 1U rack chassis but with a bit of stress to concentrate it in so reduced space.
Is it an important option to save a lot of space having a amp with 1U rack chassis? just to see if it is worth it to concentrate it in only 1U rack.

thanks

Pier Paolo

   
 
Space is premium. So the miniaturisation is important from this point of view.

However, I would imagine that the main issue for you would be the heatsink arrangement but nothing stops you from using a deeper case. I'd love to see the internal layout. Can you post some images?
 
Assuming you are talking class A/B you will consume a lot of that 1U with a torroidal transformer and heat sink. Don't even attempt an EI transformer, they get weird squashed out that flat.

Looking at this from a manufacturing cost perspective (I have before with a sharp pencil) 2U is dramatically cheaper than 1U, also low power points like 100W are a lot more expensive in $/W than higher power points.  So only 100W in 1U is more expensive than bigger more powerful amps (per watt) for multiple reasons. 

That said, there is a market niche for iU power amps (in studios), so customers will pay a premium price for a decent 1U amp. The last one I recall from peavey used a multiple secondary winding power transformer so the windings could be switched to match the power supply voltage to the load for the same power output for 4-8-16 ohm loads.

Not your typical value product, so not a big seller for Peavey, but it was a nice little iU amp (simple bipolar outputs, not MOSFET). 

JR

PS: Of course the customers would cheat and use 16 ohm PS setting with 4 ohm speakers. It would get louder just not have very much thermal headroom.
 
JohnRoberts said:
Assuming you are talking class A/B you will consume a lot of that 1U with a torroidal transformer and heat sink. Don't even attempt an EI transformer, they get weird squashed out that flat.

I am using 4 toroidal transformers (for a bimonoaural power supply) to reduce costs and space and reduce induced noise. 
Regarding heatsinks I have two external ones for better heat dissipation an lower dimensions.



 
JohnRoberts said:
Looking at this from a manufacturing cost perspective (I have before with a sharp pencil) 2U is dramatically cheaper than 1U, also low power points like 100W are a lot more expensive in $/W than higher power points.  So only 100W in 1U is more expensive than bigger more powerful amps (per watt) for multiple reasons. 

That said, there is a market niche for iU power amps (in studios), so customers will pay a premium price for a decent 1U amp. The last one I recall from peavey used a multiple secondary winding power transformer so the windings could be switched to match the power supply voltage to the load for the same power output for 4-8-16 ohm loads.

JR

the matter is that recording engineers don't know me as power amp manufacturer, so I would have a selling point for who needs an 1U rack chassis power amp for space reasons.
Regarding costs the advantage is that an 1U chassis is less expensive than 2U chassis, and moreover, my psu section is not expensive using 4 little toroidal trasformers.

 




 
sahib said:
Space is premium. So the miniaturisation is important from this point of view.

However, I would imagine that the main issue for you would be the heatsink arrangement but nothing stops you from using a deeper case. I'd love to see the internal layout. Can you post some images?

now I have only the amp module developed, but I have an idea for the layout.
 
ppa said:
JohnRoberts said:
Looking at this from a manufacturing cost perspective (I have before with a sharp pencil) 2U is dramatically cheaper than 1U, also low power points like 100W are a lot more expensive in $/W than higher power points.  So only 100W in 1U is more expensive than bigger more powerful amps (per watt) for multiple reasons. 

That said, there is a market niche for iU power amps (in studios), so customers will pay a premium price for a decent 1U amp. The last one I recall from peavey used a multiple secondary winding power transformer so the windings could be switched to match the power supply voltage to the load for the same power output for 4-8-16 ohm loads.

JR

the matter is that recording engineers don't know me as power amp manufacturer, so I would have a selling point for who needs an 1U rack chassis power amp for space reasons.
Regarding costs the advantage is that an 1U chassis is less expensive than 2U chassis, and moreover, my psu section is not expensive using 4 little toroidal trasformers.

yup.. what would I know about costs...  8)

I find it difficult to imagine sourcing 4 small transformers for the same cost as one equivalent larger one (maybe you make it up on volume  ;D ).  Then you have 4 sets of primary windings to connect up, and 4 sets of secondaries, etc. so 4x the labor.

One possible benefit, is that you could use 115V primary windings all in parallel for 115V markets and two sets of two primaries in series for 230V markets.  While for high volume production the 60Hz transformers needs less iron than 50 Hz units so could justify unique parts for each market to save a few euros (yuan). 

Another difference between 1U and 2U amps is fan effectiveness, 2U fans are cheaper and move more air, all things equal compared to 1U fans. While i suspect you are passively cooled (studios don't like fan noise).  4 small transformers will be easier to package than one big one.

Good luck.

JR
 
yes, 4 toroidal transformers are much expensive of one of the same type of 4x power, but how much does cost a toroidal trasformer of 400VA for 1U rack? The matter is that it should be a custom component, but the 4 toroidal trasformers not.
But however I don't use one trasformer but two ones for a bimonoaural power supply.

yes it is passively cooled.

 
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