Fair enough, I'll just push them out towards each corner of the chassis and call it good.
First things first, out of four MOTs I ordered, two are nicely matched, one is out in left field (half the inductance of the first two) and the fourth arrived all bent up. Ten pound choke in a padded envelope will tend to do that on a cross-country trip with the postal service. Guess they were out of flat rate boxes that day
I need to get a couple more MOTs that measure closer to the first two to get this show on the road.
Maybe pick the higher inductance ones for the bass/woofer and lower for the tweets? What value did you end up getting? Mine was packed nicely in a small box with padding inside a larger flat rate USPS box. It might be worth asking seller if he can measure inductance.
Also, you can always unwind the larger one to match a lower value one.
Also, you can always unwind the larger one to match a lower value one.
For the fun I can understand that somebody wants to use MOT's. And if you have a couple: why not (as long as you understand the dangers). But buying MOT's instead of real chokes
What is wrong with a 159 series Hammond? I paid less than 25 euro's for each ZC. Small, low resistance, all chokes identical. Inductance high enough and can deal with a decent current.
What is wrong with a 159 series Hammond? I paid less than 25 euro's for each ZC. Small, low resistance, all chokes identical. Inductance high enough and can deal with a decent current.
48.3 and 48.2 mH for the closely matched ones, 23mH for the 'special' one. I did not consider the fourth since it is not only bent up, but it arrived as a different, slightly smaller model (601 series). Seller had a bad day, I guess. All were measured with a Sencore LC-77 Z-meter.
Agree on the value proposition with the smaller Hammond chokes vs. MOTs, I'm comparing cost to the $80-$85 3-amp Hammonds since I will be using higher currents into a 4 ohm load.
For a net difference of $200 (four chokes total), I'm willing to remove the MOT secondaries if I'm not comfortable insulating them for the high voltage AC that will be generated.
For the fun I can understand that somebody wants to use MOT's. And if you have a couple: why not (as long as you understand the dangers). But buying MOT's instead of real chokes
What is wrong with a 159 series Hammond? I paid less than 25 euro's for each ZC. Small, low resistance, all chokes identical. Inductance high enough and can deal with a decent current.
Maybe it's not worth much, but physically, the 10lb MOTs are 4x the size of the 159 Hammonds and have thicker wire. I think they are capable of much higher current before saturating if compared to the 2.5lb Hammond. Typically, they are used in 1200W microwave ovens - that's about 10amps AC. Not sure what DC rating is but it seems to be holding up pretty well at nearly 2amps.
The MOTs certainly look more impressive, if that matters to you - "Big Iron" look.
99+% of the internal field does not leave the core.
99+% of any external field does not enter the core.
What little may leak-over is thoroughly swamped by the very low Source impedance of the MOSFET.
so what is the main course?
This was just an appetizer for all the great stuff NP presented at BAF.
4 ohm output, inductance
The most important reason to go for the MOT, seems to be the high current needed for 4 ohm. Ok. Agree on that.
They also look cool, I know.
The inductance of these MOT things is not that high (no gap) btw.
The 50mH inductance seems to be the minimum to get a decent power bandwidth. Around 27 Hz the inductor takes about 50% of the current. The other 50% is for the speaker. But this is only true for a 8 ohm speaker. For a 4 ohm speaker, more current is available to the speaker. Or: the inductance can be lowered to 25mH to get the same power bandwidth.
For a 4 ohm speaker, you can get away with a lower inductance. That opens possibilities for other chokes. The 159ZE has 28mH at 3A. Cheap one.
Same goes for a balanced version. Each MoFo sees half the impedance (if one side goes up, the other goes down and the middle of the speaker stays constant: you can think of it as 2 times a 4 ohm speaker in series with the centre constant). So also with a balanced MoFo you can get away with smaller inductors. Down to 12mH for 4 ohm version (159ZG).
Or am I making a stupid error (as always).
The most important reason to go for the MOT, seems to be the high current needed for 4 ohm. Ok. Agree on that.
They also look cool, I know.
The inductance of these MOT things is not that high (no gap) btw.
The 50mH inductance seems to be the minimum to get a decent power bandwidth. Around 27 Hz the inductor takes about 50% of the current. The other 50% is for the speaker. But this is only true for a 8 ohm speaker. For a 4 ohm speaker, more current is available to the speaker. Or: the inductance can be lowered to 25mH to get the same power bandwidth.
For a 4 ohm speaker, you can get away with a lower inductance. That opens possibilities for other chokes. The 159ZE has 28mH at 3A. Cheap one.
Same goes for a balanced version. Each MoFo sees half the impedance (if one side goes up, the other goes down and the middle of the speaker stays constant: you can think of it as 2 times a 4 ohm speaker in series with the centre constant). So also with a balanced MoFo you can get away with smaller inductors. Down to 12mH for 4 ohm version (159ZG).
Or am I making a stupid error (as always).
