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Modulus-686: 380W (4Ω); 220W (8Ω) Balanced Composite Power Amp with extremely low THD
Modulus-686: 380W (4Ω); 220W (8Ω) Balanced Composite Power Amp with extremely low THD
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Old 11th February 2019, 05:26 AM   #1021
pinnocchio is offline pinnocchio  Canada
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Here's a few pictures of the completed build. I have tested a few sine wave in unbalanced mode, from 10Hz to 120KHz with 1V and everything is clean. Square wave stays pretty sharp until a little over 20KHz but I'm guessing the power supply is probably the issue and using balanced signal it would be better also.

2019-02-11 01.13.11.jpg2019-02-11 01.13.19.jpg2019-02-11 01.13.26.jpg2019-02-11 01.13.36.jpg2019-02-11 01.13.43.jpg

I also tested with some music on my test speaker (very cheap speaker). This week will be connected to my main system.

All the best!
Do
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Old 11th February 2019, 07:48 AM   #1022
zman01 is offline zman01  Bangladesh
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Modulus-686: 380W (4Ω); 220W (8Ω) Balanced Composite Power Amp with extremely low THD
Do,

Maybe I should just copy and paste compliments from other posts on your build pics for various projects; would make writing the current post easier.

As usual, your latest build looks excellent - really well organized and executed., congratulations! Thank you for sharing the pics, and tell us more about the sound and synergy with your system once you get some listening done.

- Zia
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Old 11th February 2019, 01:28 PM   #1023
pinnocchio is offline pinnocchio  Canada
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Thanks Zia for the compliments!

Also, I would like to give a big thank you to Tom for making available to the DIY community some very nice products and amazing support as well!

Ciao!
Do
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PREAMPs : AMB α10 + USSPA | LDR3x + USSPA | AMPs: AMB β24 | USSA5 | TGM8 | VZ Audio NS OPS | FC-100 | Modulus-686 |
DACs : Mirand AK4490 + Discrete Output | Speakers : Troels Gravesen ATS-4 | Sagwee LT V3 |
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Old 11th February 2019, 01:57 PM   #1024
Kay Pirinha is offline Kay Pirinha  Germany
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Hi Do,
good job! May I ask why you mounted one of the boards upside down and the other one not? Is it just for optical symmetry?
As far as I know, it is always better in terms of cooling efficiency to have the power devices next to the heatsink's bottom edge?!? I suspect the LM3886's at the left handed board will get hotter at the same load than the other ones.
Best regards!
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Old 11th February 2019, 02:07 PM   #1025
pinnocchio is offline pinnocchio  Canada
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Hi Kay Pirinha,

It was not done for visual but for keeping cabling distance as much as possible the same length. The position on the heatsink is not that trivial for a Class AB, B, since when the heatsink gets the heat spread after several minutes, they become the same temperature. There's not enough heat being dissipated through this amp with the size of the heatsink and it is spread in a good length on the heatsink. I would do different with a Class A amplifier.

All the best!
Do
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PREAMPs : AMB α10 + USSPA | LDR3x + USSPA | AMPs: AMB β24 | USSA5 | TGM8 | VZ Audio NS OPS | FC-100 | Modulus-686 |
DACs : Mirand AK4490 + Discrete Output | Speakers : Troels Gravesen ATS-4 | Sagwee LT V3 |
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Old 12th February 2019, 05:44 AM   #1026
tomchr is offline tomchr  Canada
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Nicely done, Do. I love the tight and clean wire runs and the use of Tech Flex. Your way of mounting the Guardian-686 boards to the heat sinks is my favourite as well.

I'm looking forward to hearing your listening impressions.

Tom
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Old 12th February 2019, 03:19 PM   #1027
chrisb is offline chrisb
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Do, to reiterate Tom’s words - very tasty layout. Any concerns about long term heat degradation to foam adhesive on the nylon zap strap saddles attached to the heat sinks?
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Old 12th February 2019, 04:31 PM   #1028
pinnocchio is offline pinnocchio  Canada
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Thanks Tom and Chris for the compliments!

I will let you know as soon as the burn in period is done. I'm giving the amp 48 hours.

Chris,
I have these foam pads on Class A amplifier heatsinks for several years and so far they're still holding in place. One can always remove the foam and put in the 3M VHB instead.

All the best!
Do
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PREAMPs : AMB α10 + USSPA | LDR3x + USSPA | AMPs: AMB β24 | USSA5 | TGM8 | VZ Audio NS OPS | FC-100 | Modulus-686 |
DACs : Mirand AK4490 + Discrete Output | Speakers : Troels Gravesen ATS-4 | Sagwee LT V3 |
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Old 12th February 2019, 04:31 PM   #1029
cOz is offline cOz  United States
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Quote:
Originally Posted by pinnocchio View Post
Here's a few pictures of the completed build. I have tested a few sine wave in unbalanced mode, from 10Hz to 120KHz with 1V and everything is clean. Square wave stays pretty sharp until a little over 20KHz but I'm guessing the power supply is probably the issue and using balanced signal it would be better also.

Attachment 735566Attachment 735567Attachment 735568Attachment 735569Attachment 735570

I also tested with some music on my test speaker (very cheap speaker). This week will be connected to my main system.

All the best!
Do
Wow inspirational!!!
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Old 12th February 2019, 04:45 PM   #1030
pinnocchio is offline pinnocchio  Canada
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Quote:
Originally Posted by cOz View Post
Wow inspirational!!!
Thanks!
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DACs : Mirand AK4490 + Discrete Output | Speakers : Troels Gravesen ATS-4 | Sagwee LT V3 |
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