F5X -- the EUVL Approach - Page 63 - diyAudio
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Old 28th December 2011, 04:10 AM   #621
EUVL is offline EUVL  Europe
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Dave Smith said a year or so ago that leaving it out makes a big improvement.
I have not tried, as my boards are now with Mark.
I think Uwe left them out.

So depends on how experienced you are and how much risk you want to take.
It is well know that I like shorting my outputs with relays to protect the speaker.
Relay is then not in signal path.
So some current limit is useful to save the FETs.

Bear in mind the Toshiba's are becoming rare commodity.
So you should have at least a few sets in reserve.


Patrick
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Old 28th December 2011, 04:27 AM   #622
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I left it out when I replaced the IRF boards with the Toshiba board. Did not do any A/B comparison, and managed not to destroy anything...until now.

My son shorted the output out the F5 with limiter, and anly the fuse blowed. Now the cable are screwed so tight that you need a wrench to unplug them.

D.
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Old 28th December 2011, 10:48 AM   #623
audiok is offline audiok  Hong Kong
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Hi Dave,

Thanks your sharing. I will try to build your F5X version on 2012.But can you tell me the difference between "Ground x" and "Floating X" .

Br,
Tsang
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Old 28th December 2011, 03:47 PM   #624
EUVL is offline EUVL  Europe
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In the grounded x, the amp is basically two separate SE F5's driving the same speaker with out of phase signals. If you only feed a SE signal to Vin+, and 0V to Vin-, one side of the amp will be idle.

By floating the X, bit sides of the amp would be operating even in the case of a sE signal, though we still recommend you strongly to use balanced signals as input.


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Old 28th December 2011, 03:56 PM   #625
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Quote:
Originally Posted by EUVL View Post
Many thanks for posting, for the hard work over the past year despite private circumstances,
and all the testing and excellent results that is to come in the Build thread.
My pleasure Patrick. It's been a lot of fun to get to where we are.

Quote:
Originally Posted by audiok View Post
...can you tell me the difference between ground x" and "Floating X" .

Hi Tsang,

Yes, no problem.

Grounded X is essential for biasing the amplifier after construction and is also useful if you want to use each board for two separate channels. In grounded X configuration the two halves of the circuit (left and right side in the schematic posted) are essentially two separate amplifiers on one board that are configurable as a single channel in bridged mono mode or as two seperate channels. Applications like multi-channel or bi-amp come to mind...

Floating X configuration connects the left and right halves to each other in the complementary configuration so that the amplifier becomes a true fully balanced amplifier from input to output. This allows the amplifier to accept either balanced inputs or single ended, RCA type inputs.

There will be more information on this in the build thread coming soon.

Dave
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Old 28th December 2011, 03:57 PM   #626
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Hi Patrick,

Typing at the same time it would appear!

Cheers,
Dave
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Old 28th December 2011, 04:03 PM   #627
EUVL is offline EUVL  Europe
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There are some good reasons to use grounded X.

For example as Dave has said :

If you want to use the amp as SE, and you have a two way speaker with active crossover, you can run each balanced PCB as 2 power amps for one channel.
All you have to do is ground the X, raise voltages to +/-24V, change bias to 1.3A per FET, and you are in business.




Patrick
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Last edited by EUVL; 28th December 2011 at 04:06 PM.
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Old 28th December 2011, 10:56 PM   #628
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Great job guys.
I hope you take it to the next level with F5X-T..
It's going to be fun shipping *those* heatsinks around the globe..
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Old 29th December 2011, 07:54 AM   #629
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Quote:
Originally Posted by EUVL View Post
In the grounded x, the amp is basically two separate SE F5's driving the same speaker with out of phase signals. If you only feed a SE signal to Vin+, and 0V to Vin-, one side of the amp will be idle.
...which in turn, by means of adding a third output binding post tied to ground, allow you to use it as a 4 channel amp, for example for bi-amping purposes. Great flexibility!
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Old 29th December 2011, 08:25 AM   #630
qusp is offline qusp  Australia
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thanks for the final schematics guys, btw that regulator pdf is massive!!
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