Your comment on ugly MOTs got me thinking............
The build guide says build monoblocks, because monoblocks are cool. I agree, but is this the only reason for that advice? I'm curious since I am planning on four channels total, and my heatsinks would work best in a more traditional chassis with two channels per side and their fins running vertically. It will also hide my beautiful MOTs!
Is it necessary to give any consideration to the choke locations in the chassis or shield them in some way (from each other, or anything else) due to closer proximity than would be the case with monoblocks?
I've build monoblocks because I had 2 identical and not very large sinks. Using 1 for both channels would cause too much heat. I could use a bigger one, but that would be overkill. Also having 4 toroids made me build monoblocks. The plywood base plate is approx 180 mm wide and 250 mm deep. The toroid is in one corner, the Hammond as far away as possible.
The Hammond is mounted on its feet, the toroid is mounted vertically. Takes less room, and helps for hum in most cases (changing the magnetic fields by 90 degrees).In reality I have both channels sitting on one shelf. The toroid from the right channel is now hugging the Hammond from the left channel.
No hum, no noise, pitch black. The most silent poweramp I've ever build (although I've experimented more with tubes: these hum easily).
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Use smps, less expensive, more compact, lighter, no hum. 19v and 4.65amps can power even stereo MoFo. Or better yet, use 24v smps and cap multiplier for even better performance.
Here is smps measured “pitch black” (maybe it’s a personal shortcoming, but I for one, have never been able to get my toroidal linear PSU to ever measure flat pitch black like this). Here is MoFo with 24v smps and cap Mx using IRFP240 (typo in title, should read 67mH and 0.47DCR):
Here is smps measured “pitch black” (maybe it’s a personal shortcoming, but I for one, have never been able to get my toroidal linear PSU to ever measure flat pitch black like this). Here is MoFo with 24v smps and cap Mx using IRFP240 (typo in title, should read 67mH and 0.47DCR):
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Looks very black indeed (JW Double Black).
But this graph stops at 22khz. I think most SMPS run higher (50k or more). Could be interesting to measure the noise floor at these higher frequencies.
Although I don't think you will hear this hf noise (at least: not as noise).
My ears don't go this high either. The right one stops around 15k, the left one a lot sooner (with an ever lasting beep: design failure from my fathers side)
This CRC combo will end all noise for sure. The EMC is a bigger risk I think.
I doubt if it is a lot cheaper. I paid 7,50 for each 120VA toroid (surplus). German made. A (surplus) switcher is about the same.
This CRC combo will end all noise for sure. The EMC is a bigger risk I think.
I doubt if it is a lot cheaper. I paid 7,50 for each 120VA toroid (surplus). German made. A (surplus) switcher is about the same.
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I've build monoblocks because I had 2 identical and not very large sinks. Using 1 for both channels would cause too much heat. I could use a bigger one, but that would be overkill. Also having 4 toroids made me build monoblocks. The plywood base plate is approx 180 mm wide and 250 mm deep. The toroid is in one corner, the Hammond as far away as possible.
In reality I have both channels sitting on one shelf. The toroid from the right channel is now hugging the Hammond from the left channel.
No hum, no noise, pitch black. The most silent poweramp I've ever build (although I've experimented more with tubes: these hum easily).
I'm planning on using an external Dell 12V 18A SMPS (my MoFo will be driving 4 ohm speakers), so not worried about interference from power supply components. I was just not sure about any EM interactions/interference from one choke to another if they are relatively close together in a single chassis.
Briansz, so mewhere here we have a discussion about interactions between inductors. It was noted that the more psysical seperation between them the better. Then an observation concerning an unusual orientation like as follows. Assuming you have a pair of inductors that ar 2 " long and 1/2" in diameter. If you place them upright but inclined at a 43 deg. ? angle like the leaning tower of pisa the interfierence is drasticly redused . At least I thought it was 43 degs.
I'm not familiar at all with how far the magnetic field in a choke travels in free air, hence my question.
Unless I'm playing test tones, it stands to reason that each of the chokes will have varying magnetic fields with respect to one another when a signal is present.
I don't have a problem with isolating them from one another in steel transformer cans or with sheet metal, just want to make sure I don't overlook this detail when designing the amp chassis. Would be lousy to retrofit.
I'll search for the thread you refer to, thanks.
Unless I'm playing test tones, it stands to reason that each of the chokes will have varying magnetic fields with respect to one another when a signal is present.
I don't have a problem with isolating them from one another in steel transformer cans or with sheet metal, just want to make sure I don't overlook this detail when designing the amp chassis. Would be lousy to retrofit.
I'll search for the thread you refer to, thanks.
one can do it scientific way ..... or some another
what's max signal amplitude in MoFo choke , what's resulting magnetic field in choke proximity ....... etc. (yadayada)?
or ...... you can trow all that through the window , starting purely from Engineer point of view , realizing that Hammonds are having bloody steel covers ..... not needing more for proper Faraday cage(ing)
even without those , I wouldn't loose my sleep over .......
what's max signal amplitude in MoFo choke , what's resulting magnetic field in choke proximity ....... etc. (yadayada)?
or ...... you can trow all that through the window , starting purely from Engineer point of view , realizing that Hammonds are having bloody steel covers ..... not needing more for proper Faraday cage(ing)
even without those , I wouldn't loose my sleep over .......
Mot has no cover. Neither do the 159 Hammond's.
But I fully agree with ZM. I wouldn't loose any sleep. If you are loosing sleep: keep the chokes as far away as possible and/or change the angles. Same as filter design in a speaker.
Remember the magnetic fields are small for small signals. Only loud low frequencies will generate real fields. No worries. And if you know what channel seperation vinyl has....
But I fully agree with ZM. I wouldn't loose any sleep. If you are loosing sleep: keep the chokes as far away as possible and/or change the angles. Same as filter design in a speaker.
Remember the magnetic fields are small for small signals. Only loud low frequencies will generate real fields. No worries. And if you know what channel seperation vinyl has....
.......GFP-70 ......
And, it will swing 30Vpk.
besides usual question (will it drive F4 ?
) , I have one more - that type number is correct ?was puzzled , but now confused , searching for GFP-70
Fun aside:
Last weekend, I modified an ADCOM GFP-750 for 19dB gain to drive some MoFos.
My initial opinion is that the ADCOM sounds a little better with more gain (and, of course, more distortion)
And, it will swing 30Vpk.
Good result. I was ably to get 27v before clipping on 18.6v. What’s your supply voltage?