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Old 14th January 2013, 12:12 PM   #901
bcmbob is offline bcmbob  United States
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Both work well and the choice is dependent on the other equipment in a system. I have had great results with a bare pot, LDR attenuation and an active pre. Your desired SPL and your speaker sensitivity will dictate what you use.
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Old 14th January 2013, 11:46 PM   #902
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Default Any interest for a 'Redux' FE?

In these days I'm playing a bit with a reduced FE board:

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

This PCB differs from the standard FE one in the following:
  • smaller (same dimensions of TP board, it should be a near perfect replacement in actual builds, including drilling and heatsink mounting)
  • same input cap limitation of TP board (22.5mm lead spacing)
  • single bridge, a bit less performing but allow the use of a single transformer for two monoblocks.
  • Not as optimally spaced and optimized as Fremen Edition board.
I've designed it just for fun but maybe it could be interesting for some.


Any comment is welcome...
Attached Images
File Type: jpg Fremen Redux Edition.jpg (482.1 KB, 643 views)
File Type: jpg My_Ref_FRE Top.jpg (385.2 KB, 634 views)
File Type: jpg My_Ref_FRE Bottom.jpg (232.6 KB, 348 views)
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Old 15th January 2013, 09:12 PM   #903
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Dario,

Very interesting. It looks like the big power supply caps are the same size. Is this correct? Personally, I find the single bridge interesting as it makes it easier to bi-amp and tri-amp speakers. The cost of transformers for multiple monoblocks is a bit higher, but they also take up a lot of space.

I have powered both channels of my FE using one transformer with circuits in parallel and without problems. The shorted input hum measured the same and it sounded the same, so even though monoblock is the recommended approach, I am comfortable with either the dual bridge or single bridge approach.

As for the smaller input cap, so far I have been using caps that are either too big (K75) or a very tight fit (K71). I don't mind the cap extending "off-board".

Very nice work. How much different from optimized do you see this board?

Jac
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Old 15th January 2013, 09:52 PM   #904
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Hi Jac,

Quote:
Originally Posted by lehmanhill View Post
Very interesting. It looks like the big power supply caps are the same size. Is this correct?
No, they're 30mm like in TP boards.

BTW the FE BOM uses 30mm caps so not a real difference.

Quote:
Originally Posted by lehmanhill View Post
I have powered both channels of my FE using one transformer with circuits in parallel and without problems.
Good to know

Quote:
Originally Posted by lehmanhill View Post
As for the smaller input cap, so far I have been using caps that are either too big (K75) or a very tight fit (K71). I don't mind the cap extending "off-board".
Yes, not a big limitation.

Quote:
Originally Posted by lehmanhill View Post
Very nice work. How much different from optimized do you see this board?
Thanks

Particularly on the upper left corner area the layout is too much congested, the DC protection circuitry is probably too much near to the input cap.

If this is a problem in a real build... who knows... we should build it and, possibly, measure.
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Old 17th January 2013, 12:02 PM   #905
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BTW , how much money do I need to save for pcb's or kits (planning holidays soon, need to allocate money) for FE ? What is an estimate ?
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Old 17th January 2013, 09:07 PM   #906
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Quote:
Originally Posted by voxxonline View Post
BTW , how much money do I need to save for pcb's or kits (planning holidays soon, need to allocate money) for FE ? What is an estimate ?
Parts

Around 76€ per board (premium industrial BOM) which can be lowered to 52€ (On a budget BOM)

PCBs

It will depend on the number of partecipants....

50 PCBs (25 stereo kits) -> 18€ each
100 PCBs (50 stereo kits) -> 14€ each
200 PCBs (100 stereo kits) -> 13€ each
300 PCBs (150 stereo kits) -> 12€ each
400 PCBs (200 stereo kits) -> 11€ each
500 PCBs (250 stereo kits) -> 10€ each

These prices are an estimate for a single PCB, they include 1€ donation to DIY Audio and PayPal fees, they're subject to change.
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Old 18th January 2013, 05:23 AM   #907
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Thank you
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Old 29th January 2013, 08:41 AM   #908
atupi is offline atupi  Romania
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Worth spending extra 100Euros for two R-core's 120VA 2x24v ?
Now i'm using two toroids 250VA each.

Any body who moved from toroids to R-core can share some impressions ?
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Old 4th February 2013, 04:43 PM   #909
SoIL4x4 is offline SoIL4x4  United States
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Default update

I am almost ready to finally power up these boards, but I am waiting for some rikens from parts connexion so I had a little spare time this week. I decided to do a little enclosure work. Most of what I have put together so far is from parts and pieces that I have laying around, except the copper. I had to run to the hardware store for it.

Here are a few blurry cellphone pics..let me know what you think
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File Type: jpg 2013-02-04_05-42-48_934.jpg (462.4 KB, 55 views)
File Type: jpg 2013-02-04_05-43-41_482.jpg (404.5 KB, 62 views)
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Old 4th February 2013, 07:57 PM   #910
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Quote:
Originally Posted by atupi View Post
Worth spending extra 100Euros for two R-core's 120VA 2x24v ?
(...)
Any body who moved from toroids to R-core can share some impressions?
IMHO yes, my 120VA R-Cores sound fuller and more powerful than my 225VA Toroid toroids.

But it seem I'm the only one that made a comparison...

Quote:
Originally Posted by SoIL4x4 View Post
I decided to do a little enclosure work. Most of what I have put together so far is from parts and pieces that I have laying around, except the copper. I had to run to the hardware store for it.
Wow! Impressive work!

If' you're asking about layout I think it's pretty good very similar to the one I'm using.

I would, BTW, consider a plain Furutech gold plated inlet in place of the filtered one I can see in pictures.

Click the image to open in full size.
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