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Modulus-86  build thread
Modulus-86  build thread
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Old 16th May 2019, 07:12 AM   #4631
radiotron is offline radiotron  New Zealand
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Very nice work Anand, the stack is rather clever!
@ Tom, idea of " THAT Driver and THAT Receiver in one board" appeals a lot here, fine with some SOIC parts in a DIY, had to get used to them in servicing a long time ago.
And PS, the Modulus-86 build in the repurposed chassis is working perfectly, even got it a new 20 amp house circuit to plug into. It seems to like lower mains impedance.
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Old 16th May 2019, 10:07 PM   #4632
tomchr is offline tomchr  Canada
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My original plan for the universal buffer was to deliver a fully assembled module based on SMD parts, however, many DIYers aren't liking that idea much. The experience of building from scratch is important to many DIYers, so my current line of thought is to make a board that uses SOIC (large surface mount) ICs and leaded passives (resistors, caps, etc.). I think I can get most of the performance out of the parts that way and still serve the DIY market.
The only drawback is that the circuit will use at least one SOIC per channel and you will need to solder them if you want to build the circuit.

Some may ask why I don't just make an SMD boards and let people solder that. Well, there are many reasons, the cost of support being the main one. SMD builds are nearly impossible to debug by email and many lack the tools to de-solder SMD components. In addition, the components (especially caps) tend to crack if you overheat them or if they contain moisture. These cracks may not be noticeable to the naked eye, but will result in degraded performance and "weird" effects like crackling noises and distortion. In addition, some DIYers have health issues, which prevent them from being able to solder itty-bitty parts. Therefore, I will not make an all-SMD board available.

Timing: I'm currently working on a headphone amp and on a front-end to my distortion analyzer, so I can measure the headphone amp. Those projects have the highest priority. I hesitate to make promises about the universal buffer, but it could happen as early as this fall. Sooner if the other projects go well.

Tom
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Modulus-86, 186, 286, 286 Kit, & 686: 40-240W (8Ω) at <-120dB THD. HP-1: 3W/20Ω, -130dB THD, 128dB DNR.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 17th May 2019, 12:13 AM   #4633
tomchr is offline tomchr  Canada
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I found a matched pair of Modulus-86 Rev. 2.3 in my lab. I occasionally build these to take pictures and measurements for the design documentation. I have no further use for these and would rather see them go to good use by one of you folks.

You can find them here: Modulus-86 Rev. 2.3 Matched Pair | Neurochrome :: Audio

Last I had a pair of MOD86es sitting around they were snatched up pretty fast. If you don't see them listed in the Power Amplifiers section of my website, it's because they've sold.

Tom
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__________________
Modulus-86, 186, 286, 286 Kit, & 686: 40-240W (8Ω) at <-120dB THD. HP-1: 3W/20Ω, -130dB THD, 128dB DNR.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 17th May 2019, 02:40 PM   #4634
Mark Johnson is offline Mark Johnson  United States
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Quote:
Originally Posted by tomchr View Post
Power-86 is now in Rev. 1.2.

The CRC snubber needs to be designed for each transformer
diyAudio member JeffYoung has put together a list of transformers and the CRC snubbers that tame them. There are more than 25 transformers on the list, and it continues to grow. It includes transformers made by Plitron, Antek, Talema, Toroidy, Hammond, Block, and others. It's a handy way to double check your own results, or if you're brave, to sidestep making your own measurements entirely.
Link: Quasimodo results (ONLY)
Does the transformer wiring change the damping factor (thus the optimum value of snubber components) appreciably? Not really. You can prove this to yourself by connecting the transformer to Quasimodo snubber jig and dialing it to optimum (critical damping, zeta=1.0). Now dramatically change the transformer wiring somehow. Idea1: if you've twisted the secondary leads, untwist them. Or vice versa. Idea2: splice in another 2 feet of wire length between the transformer secondary and the test jig. After making the dramatic change, display the secondary ringing waveform. Has it changed much? Not really. Is ringing still damped to oblivion? Yes. What do we conclude? Changes to the transformer wiring don't have much effect upon the damping factor or the optimality of the CRC snubber.

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