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Old 21st April 2011, 03:59 PM   #151
qusp is offline qusp  Australia
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no, you need 4 matched pairs of 2sk1530/j201 and for a good np match of these fets that is not really high, considering unmatched from most vendors is only a couple of dollars less

Last edited by qusp; 21st April 2011 at 04:04 PM.
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Old 21st April 2011, 04:05 PM   #152
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4 matched pairs of 2sk1530 & 4 matched pairs of j201, thats 8 matched pairs.
8 x 28 = usd224.00. correct? Possible to matched ourselves to spec?
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Old 21st April 2011, 04:08 PM   #153
qusp is offline qusp  Australia
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no, you need 4 x matched k1530/j201 pairs, they are complementary devices. but someone correct me here if i'm off track. is it more important to match within same devices, so that the 4 x k1530 are very close and the 2 x j201 are very close and then that each quad is as close as is possible with an NN NN|PP PP pairs, because bias between the poles can be balanced with tweaking??. its best that all 8 are close, but N and P cannot truly be matched. i may be totally off base there and i'm sure someone will correct me if i am

Last edited by qusp; 21st April 2011 at 04:18 PM.
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Old 21st April 2011, 04:25 PM   #154
ashaw is offline ashaw  Australia
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In these devices you can get a pretty good match between P and N, and as such you can get a matched set of 8 with 4 of each type. yes it is expensive, however it will be worth it.

Last edited by ashaw; 21st April 2011 at 04:27 PM.
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Old 21st April 2011, 04:41 PM   #155
qusp is offline qusp  Australia
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nice!!, yeah i guess my sense of what is expensive is out of whack, i guess i just meant comparatively, but lots cheaper than buying a couple of rails and matching them yourself
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Old 21st April 2011, 06:10 PM   #156
EUVL is offline EUVL  Europe
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Each channel of F5X uses 4 MOSFETs, 2x 2Sk1530, 2x 2SJ201, all matched to each other.
So for a stereo amp, you need a set of 8 matched devices in total.

It is "expensive" as you said. But you would also be paying 300 USD for 2 transformers, something of the same amount minimum for a decent case,...... And if anything, it is worth spending money on devices which has a most direct impact on the soinic results.

So it will not be a USD600 budget amp. I am sure you can build an F5X circuit with that budget, with less selected, lower cost components. There are many threads around to tell you how to do that. But that is not what we are trying to achieve here.

As I said in Post #1, there are hundred ways to skin a cat.


Patrick
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Old 22nd April 2011, 03:13 AM   #157
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Quote:
Originally Posted by EUVL View Post
Each channel of F5X uses 4 MOSFETs, 2x 2Sk1530, 2x 2SJ201, all matched to each other.
So for a stereo amp, you need a set of 8 matched devices in total.
Ok, so for our dual mono, we need 2 matched pairs for each channel ( ie. 2 x 2Sk1530 + 2 x 2SJ201).

Total = 4 matched pairs (4 x 2Sk1530 + 4 x 2SJ201, all matched)

Both channels' mosfets should matched each other, meaning the left channel's pairs should also matched the right channel's pairs.
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Old 22nd April 2011, 03:54 AM   #158
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Quote:
So it will not be a USD600 budget amp. I am sure you can build an F5X circuit with that budget, with less selected, lower cost components. There are many threads around to tell you how to do that. But that is not what we are trying to achieve here.

As I said in Post #1, there are hundred ways to skin a cat.
My wife is going to skin me. Sorry for the non technical comment.
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Old 22nd April 2011, 06:18 AM   #159
h_a is offline h_a  Europe
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Well, if one wants to save some bucks, different output fets are also an option as the fine Toshiba parts are next to Semisouth parts the most expensive fets.

Will it sound different? Likely so, but to the better or worse is up to personal taste.

The smallest change is to not match between N and P, as these parts are never really identical anyway.

Hannes
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Old 22nd April 2011, 07:12 AM   #160
EUVL is offline EUVL  Europe
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Please keep this thread only for technical discussions.

After about a week's discussion with the forum (to see how our PCB could fit into the case design they are working on, separately), we have finally come to an agreement that everyone is happy with. So we can now go to the prototyping phase to make sure the PCB is error free before making it available to all.

My most sincere thanks to fitzfish for the hundreds of hours he spent on the PCB. I didn't realise how difficult it is to get all these curvy tracks with PCB software. But he did it all by hand, to my perfect satisfaction, without a word of complaint, or even letting me know it was that difficult. So it will be the first, and probably the last curvy track PCB you can get from the forum.

Finally we are progressing.


Patrick
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