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Old 6th June 2013, 06:11 PM   #731
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Funky setup
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Old 17th June 2013, 02:12 AM   #732
i2k92 is offline i2k92  Indonesia
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Crappy photography of an amazing amp Hypex UCD180HG + Connex SMPS300RE :
Click the image to open in full size.

fired up last night, except for some boominess on the bass (which I hope will go away after some break in period), this baby sounds better than my Hifimediy T1 & T2 & Charlize TA2050.
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Old 18th June 2013, 10:18 AM   #733
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Quote:
Originally Posted by Wieslaw Lipowsk View Post
Here's my heavily tweaked Class-D amplifier
Well, you replaced the output-inductors for what reason? They look totally underrated. Those capacitors are lowESR-types 105C with desired rated ripple-current suitable for this amp?
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Old 18th June 2013, 10:23 AM   #734
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I replaced the inductors according to Trevor's tutorial:
Trevor Marshall - Class D Audio Amplifier Design - TDA7498 Output filters

The electrolytic caps I got with the board were SMD type, so I decided to replace them, too. They are all in the PSU section.
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Old 18th June 2013, 01:48 PM   #735
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Did you do any measurements on those modifications?

I actually can't understand why someone is changing caps "just because". Whats wrong with this SMD-Type caps?

Don't get me wrong, i'm just asking to understand why someone, or in this case you, changed this.

Circuit design/improvement is alot more than just changing some caps/inductors and "sure electronics" are doing a good job on this.

:-) Cheers
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Old 18th June 2013, 02:39 PM   #736
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My ears were my guide, the amp now makes the sounds beautifully, that's enough for me. I bought two of those and made the changes only on one, and always compared the one to th other during improving.

SMD electrolytic caps and other passive SMD parts are not thought to be as good as regular ones. Also, I added some capacitance and their voltage is now 63V, and not 50V as before. Just look at the boards on PE website - the 220uF caps are all regular, I got one of the boards with SMD 220uFs.
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Old 18th June 2013, 03:12 PM   #737
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Quote:
Originally Posted by Wieslaw Lipowsk View Post
SMD electrolytic caps and other passive SMD parts are not thought to be as good as regular ones.


Wow dude! Who told you that? SMD caps and "regulars" are made the same way. They just differ from the connections. SMD passives have alot less inductance, thanks to the missing connection-legs. So ESL is a way lower.

If you want "better" electrolytic, go for "solid-polymer". -> Super low ESR, highest ripple current rating, super long life. You could also go for massive parallel MLCC ceramics. (Which have some other disadvantages)

Business | Industrial Devices | Products | Passive & Electromechanical

But well then, if your ears like it - go for it.
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Old 18th June 2013, 03:36 PM   #738
redjr is offline redjr  United States
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Quote:
Originally Posted by doctormord View Post
Did you do any measurements on those modifications?

I actually can't understand why someone is changing caps "just because". Whats wrong with this SMD-Type caps?

Don't get me wrong, i'm just asking to understand why someone, or in this case you, changed this.

Circuit design/improvement is alot more than just changing some caps/inductors and "sure electronics" are doing a good job on this.

:-) Cheers
I find this practice a re-occurring theme for many DIY'ers. The perceived improvement by changing components is either anecdotal, or subjective. I find very few who offer any kind of metrics to substantial their claims. But then there's this whole school of thought that pit specifications against the sound that you hear - often concluding the two have no absolutely no bearing on each other. There are entire threads that support these theories. But, I've quit trying to argue either way, and look at any component level change with a very skeptical eye - realizing that no serious double-blind testing was ever done, and hence the conclusion of the observation is flawed from the beginning. I think someone aptly called it 'expectation bias'.
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Old 18th June 2013, 04:20 PM   #739
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I just wonder about so many "misleading" informations around. I mean, there is a difference between i.e. MKP & MKS capacitors - they made differently. :-) But the question is always, will the different params affect my needs in the right way.

I actually call it "there is a problem for every/any solution" as nowadays everyone is trying to sell "problems".

OT: For the blind test - some weeks ago a couple of guys and me speculated about different "cable-sounds" and we simulated alot of params which lead to cause this. Well, cables sound "different" BUT the problem mostly is not the cable, it's the outputstages/prestages/bufferstages/inputstages which causes the variation in sound as they are mostly balanced and/or calculated to a specific cable in the test-rig. At the final stage we went into alot of mathematics and complex cable models. Conclusion: A significant improvent can be done with an active ground-driver.. i.e. via jfet-circuit when there is no way to change the interface at all.

But thats a way to offtopic to this thread.

Cheers
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Old 18th June 2013, 06:35 PM   #740
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Quote:
Originally Posted by doctormord View Post


Wow dude! Who told you that? SMD caps and "regulars" are made the same way. They just differ from the connections. SMD passives have alot less inductance, thanks to the missing connection-legs. So ESL is a way lower.

If you want "better" electrolytic, go for "solid-polymer". -> Super low ESR, highest ripple current rating, super long life. You could also go for massive parallel MLCC ceramics. (Which have some other disadvantages)

Business | Industrial Devices | Products | Passive & Electromechanical

But well then, if your ears like it - go for it.
I am not an expert. I just followed Trevor's advice and replaced the SMD caps and resistors in the input and output stages of the TDA7498. I replaced the 220uF/50V SMD electrolitics with 470uF ones I just had at hand. I am not in position to discuss the rest of your comments.
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