Actually, if you slot the end of a dowel instead of drilling a hole, it's easier to remove the coil without messing it up getting the wire out of the hole. I use a short piece of 7/16" slotted in one end and it works very well.
Mike
Last edited:
For a related project I needed to make some inductors. I found temco_industrial_power on ebay had a wide selection of magnet wire in small quantities and very low total cost. I had it in one day and it worked out great. Just passing along a good source for those who need it.
As for technique, I rummaged through my tools and came up with a massive screwdriver with just the right diameter and a very convenient ergonomic handle...
BK
As for technique, I rummaged through my tools and came up with a massive screwdriver with just the right diameter and a very convenient ergonomic handle...
BK
I hope it wasn't a flat-bladed massive screwdriver as the blade might prevent your removal of the coil without serious deformation. Been there, done that
Fortunately no, although I did contemplate that!
It was a very nice Facom brand phillips with a smooth and straight shaft and a hex section near the grip put a wrench on if necessary - a real cadillac of a tool, but so large that I rarely have a need for it. Facom is sorta rare in the USA - Snapon and Mac are the pro-level names here.
FYI, online calculators exist to figure the diameter vs. coils and length required for a particular mH value.
BK
A piece of 1/4" schedule 40 PVC pipe would be perfect. The OD is 0.540", which is about the same as the AA battery I recommend using as a coil former.
A piece of 1/2" copper pipe would work too, though at 0.625" OD, you'll probably want to go with 14 turns rather than the 15 I normally recommend.
Some 1/2" diameter delrin rod would work as well. I think FR4 fibre glass is available in rod shapes as well. McMaster-Carr and Online Metals are your friends here.
Perhaps your local home & garden store can help you out with a pipe nipple of the appropriate dimension if you want your inductors to be a bit prettier than what's achievable by winding them on an AA battery. I'd probably go with a plastic coil former to avoid scratching the enamel off the wire.
Tom
A piece of 1/2" copper pipe would work too, though at 0.625" OD, you'll probably want to go with 14 turns rather than the 15 I normally recommend.
Some 1/2" diameter delrin rod would work as well. I think FR4 fibre glass is available in rod shapes as well. McMaster-Carr and Online Metals are your friends here.
Perhaps your local home & garden store can help you out with a pipe nipple of the appropriate dimension if you want your inductors to be a bit prettier than what's achievable by winding them on an AA battery. I'd probably go with a plastic coil former to avoid scratching the enamel off the wire.
Tom
Last edited:
You can use an XLR to RCA converter but I would make sure that the adapter doesn't short the negative XLR to ground
Your dad will get over the loss, I'm sure... The sacrifice was worth it.
I do wonder if it's necessary to lob the end off, though. The square end of the extension isn't larger than the diameter of the middle portion. Also the wire does tend to spring back a little, so you should have some amount of wiggle room to work with.
Neat idea, though. I'll try that next time I need to wind one of those inductors.
Tom
In this case, the square end of the extension had a flare for some reason which would have made it impossible to remove the coil without messing it up. I had another extension which didn't have the flare, but that one didn't have the hole to feed the wire through. A dowel with a slot on the end (like mentioned above) would have been best, but I was too anxious to try and locate one lol.
Anyway, for my next build, I was thinking about building a multiple Modulus86 setup (maybe 6 units). Something that can be run in parallel for more power or individually if I ever decide to use it in a home theater system or something.
I have a few questions:
How many Modulus86 units can be run in parallel? Is there a risk of instability if there are too many? Does the THD increase linearly with each amp or is it the sum or squares or something?
How does two Modulus86 units in parallel compare with the Parallel86?
Thanks
Ah, A wobble bar? Yeah I would have been grumpy too.
As for the paralleling, you can't. Long answer from Tom is buried somewhere in the thread. However the death of Par-86 does mean that there is a hole to fill in the product line...
There would be different interpretations as to what is better bass. You could provide less damping which will make the bass seemed extended at the expense of other aspects. Interaction between speaker and amplifier can be different with different designs. Some people like excessive bass, some not so much. My experience is that if a bass is well produced, some notes that will make your chest resonate at certain frequencies in live performance will also do so on a good system. You can feel it even though the notes may not be loud.
Finally some good measurements.....but I digress this is the beginning of what we should be measuring ...good on you Tom!
your staring to get my interest
Lawrence
The original Modulus-86 Rev. 1.0 could, in theory, be run in parallel. The idea was to build a modular amplifier that you could connect in bridge, parallel, and bridged parallel, hence the "Modulus" name. However, the LM3886 can only drive an 8 Ω load in a bridge configuration. This is due to the output current capabilities of the LM3886. For the parallel configuration, I was able to get better performance by running the two halves of an LM4780 in parallel and as far as I know, nobody ever built the Modulus-86 in a parallel configuration.
From Modulus-86 Rev. 2.0 this option was removed. Modulus-86 Rev. 2.0 and beyond can be bridged, but can only drive a 8 Ω load in this configuration. Modulus-86 Rev. 2.0 and beyond are not designed to be run in parallel.
The Parallel-86 is a different design. There are many challenges in a parallel LM3886 design and it gets further complicated by the composite amplifier topology. I tackled these challenges head on and arrived at a solid amplifier. Sadly, TI decided to discontinue the LM4780, so the Parallel-86 is gone. I have one board left. If anyone needs a sub driver, here's your opportunity.
While there may not be a technical need for more power, there definitely is a perceived need for more power. The 60 W (8 Ω) of the Parallel-86 wasn't enough to pass the psychological barrier of 100 W, so it was never a big seller. I've sold more boards after TI discontinued the LM4780 than I did in the first nine months of the project. Consumer psychology...
Anyway. I'll need to address the 100+ W market somehow. It won't be with a chip amplifier.
Tom
For all the complaints about the old audio magazines (High Fidelity and Audio) being mouthpieces of their advertisers, at least one of them attempted to give specs in their power amp reviews in units if dBW -- max output on log/decibel scale referenced to 1W. That potentially gave customers a better perspective on the output capabilities of one amp vs another. Never caught on, though.
While there may not be a technical need for more power, there definitely is a perceived need for more power. The 60 W (8 Ω) of the Parallel-86 wasn't enough to pass the psychological barrier of 100 W, so it was never a big seller. I've sold more boards after TI discontinued the LM4780 than I did in the first nine months of the project. Consumer psychology...
Anyway. I'll need to address the 100+ W market somehow. It won't be with a chip amplifier.
Tom
Funny that I am building 12 of your Parallel-86 boards as we speak! 4 of them bridged for a sub amp, and the other 8 for an HT amplifier split into 2 chassis of 4 channels each. Whew!
Best,
Anand.
Funny that I am building 12 of your Parallel-86 boards as we speak! 4 of them bridged for a sub amp, and the other 8 for an HT amplifier split into 2 chassis of 4 channels each. Whew!
Yeah... You're the exception that confirms the rule.
I suspect there is a psychological barrier at 100 W. If your amp can deliver 100 W, it's taken seriously. If it can only deliver 99 W, it's taken less seriously. It doesn't matter much that your 99 W are the best in the world or that typical listening levels require, maybe, 100 mW or 1 W.
Humans are not rational creatures. As Dan Ariely notes, we're "Predictably Irrational".
There are exceptions. Some have large home theatres or listening spaces and legitimately need the power. Many don't, though.
I like the idea of specifying power in dB. After all, the difference between the Modulus-86 (40 W, 8 Ω) and a 200 W (8 Ω) amp is only 7 dB.
Tom
Last edited:
There's one in every crowdYeah... You're the exception that confirms the rule.
Haha, yeah.
You gotta have that 100W for when you want to party.
Agreed.
I run a pair of tweaked Behringer B2031A 8" 2 ways powered by 3 LM3886 amps, the lows runs paralleled 3886's separated by 0.1 ohm resistors and no feedbacks interactions.
B+/B- rail voltages are around 40V.....claimed Highs 75W + Lows 150W at 0.1%...hmmmm.
What ever the actual power is, these things go quite seriously loud and with cranking bass.....but then they run out of grunt.
For normal living, yes only 100's of mW are required, but when the party really gets going 3 3886's are not enough.
Yeah, makes perfect sense.
Dan.
Extra treat for you - I've just finished putting together Tom's differential pre-amp so you can hear a complete Neochrome pre/power set up