It's on purpose. You add R14 if you want gain higher than 20 dB. But 20 dB is plenty for the vast majority of systems and lower gain means lower noise. Some add a bit of gain to make the Modulus-86 match other amps.
I love the Tower of Power in @solhaga's build. Those are nice and compact amps.
Tom
I don’t post on this forum much, but had to come over once I did a test run on my Modulus 86 build. This is a fantastic amp! I’ve been on a tube kick for a while and even using vinyl as a source the background is black and the imaging is superb.
Currently setup with a Thorens TD-121 running and AT VM-95ML into a Hegeman Hapi 2 preamp with the Modulus 86 driving a pair of Yamaha NS-690’s.
Tom’s documentation was easy to follow and very helpful as well. Thanks for the great amp Tom!
Currently setup with a Thorens TD-121 running and AT VM-95ML into a Hegeman Hapi 2 preamp with the Modulus 86 driving a pair of Yamaha NS-690’s.
Tom’s documentation was easy to follow and very helpful as well. Thanks for the great amp Tom!
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Very nice build there. Thank you for sharing. I'm glad that it came together nicely and that you like the result.
Where did you get the chassis? It looks professionally made.
Tom
Where did you get the chassis? It looks professionally made.
Tom
Thanks! The chassis came from Par Metal Products out of New Jersey, they sell on eBay as pimetalproducts. I’ve had a few different projects in the chassis.
I’d like to get a set of rack handles for it and install an indicator lamp on the front. Right now it just has a lighted switch on the back I scavenged from a dead Dynaco 410.
The Modulus drove my AR 303’s this morning and the heat sink got a little warm, but still not bad. They’re 4 ohm and 85db. I think my trusty Stereo 70 will be on the shelf for a while.
I’d like to get a set of rack handles for it and install an indicator lamp on the front. Right now it just has a lighted switch on the back I scavenged from a dead Dynaco 410.
The Modulus drove my AR 303’s this morning and the heat sink got a little warm, but still not bad. They’re 4 ohm and 85db. I think my trusty Stereo 70 will be on the shelf for a while.
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Looks like these guys: http://par-metal.com/
Their prices are quite reasonable. Better than ePay by the time you include shipping. Thanks for the tip.
Tom
Their prices are quite reasonable. Better than ePay by the time you include shipping. Thanks for the tip.
Tom
Made progress on the project and now it’s complete! Checked for voltages and offset, everything checked out well. Currently playing this with my ELACs speakers.
Missing power button though. Front plate is thick at 8mm and switch I planned to use did not fit.
Looking for suggestions for a good replacement.
Missing power button though. Front plate is thick at 8mm and switch I planned to use did not fit.
Looking for suggestions for a good replacement.
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Or an Intelligent Soft Start: https://neurochrome.com/products/intelligent-soft-start
Mouser has them. The search term is: "Cable tie mount". You can then select if you want adhesive or screw mount.
Tom
I just received a couple of these boards to try out. I've used a number of Tom's other boards and modules in various projects.
There is no information regarding C27 in the printed BOM in the documentation and it does not seem to be included in the Mouser BOM. Is this part no longer being used?
EDIT: Never Mind - I figured out that it was the second line for Item 4 - 100nF.
There is no information regarding C27 in the printed BOM in the documentation and it does not seem to be included in the Mouser BOM. Is this part no longer being used?
EDIT: Never Mind - I figured out that it was the second line for Item 4 - 100nF.
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Finally getting around to putting my Mod86 boards in a chassis. Good progress this evening.
The plan is to use PowerCon inlets from my existing +/-24VDC outboard power supply. Just those, input RCAs, and binding posts left to attach.
Simple little chassis 330W x 180D x 130H (mm).
The plan is to use PowerCon inlets from my existing +/-24VDC outboard power supply. Just those, input RCAs, and binding posts left to attach.
Simple little chassis 330W x 180D x 130H (mm).
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Oh, neat. I like the heat sinks. They look like they were made for use with either a rectifier/SSR brick or stud-mounted diodes or thyristors.
Can't you squeeze the power supply into that void between the boards?
Tom
Can't you squeeze the power supply into that void between the boards?
Tom
Yes, I probably can… The Connex SMPS I have available for these (and successfully tested them with before) is +/-36VDC. If it’s too close and noisy I can maybe squeeze in a couple of Mark J’s filters…
I did want to give my big dual mono linear power supply a try with the Mod86s, though. I’ll still try that without permanent holes put in the rear panel and compare with the SMPS.
Thanks for the practical suggestion, Tom.
I did want to give my big dual mono linear power supply a try with the Mod86s, though. I’ll still try that without permanent holes put in the rear panel and compare with the SMPS.
Thanks for the practical suggestion, Tom.
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The Connex will be fine. I've used the SMPS300RE, SMPS300REh, and SMPS800RE with the Modulus amps with good results. In the Modulus-286 Kit (LE) I had the SMPS practically on top of the amp and even that was fine. I did have to rotate the SMPS so the rectifier wasn't over the input to one of the channels as that rectifier emits some mains hum.
Tom
Tom
Fine with 8 ohm load, limited output with 4 ohm load.
https://www.diyaudio.com/community/threads/modulus-86-build-thread.267802/post-7368646
https://www.diyaudio.com/community/threads/modulus-86-build-thread.267802/post-7368646