given the lower mH needed (than say.. current source), worth winding your own flying saucer/Saturn's ring air core? just thinking.. It's a shame that transformer parts seem to cost as much as transformers.
Two windings wire diameters show.
No doubt the tiny one can't handle ~2 A
how much max current for thick wire
you have better DVM than do just used an old radioshack...and my LCR bridge is a Chinese one
the primary coil can handle a crap load of current..more then needed, I do not have an amp bread board as of yet give it a go, listen to it 🙂
Soundhappy,
I want to know where you get all you microwave chokes from? Local dumpster bin where dead microwaves find their demise? Or late night sweeps of the neighborhood before trash pickup day? 🙂
I want to know where you get all you microwave chokes from? Local dumpster bin where dead microwaves find their demise? Or late night sweeps of the neighborhood before trash pickup day? 🙂
@ Xrk971
In doing electrician job and we have always short pieces of copper or aluminium cables left overs
so we stock them and after urban local metal recycling point buy from us all metals parts.
Check your city metal recycling company and see if you can buy used heat sinks, copper wire and transformers
refurbished from machines you be surprised by the low cost and find good deal :
Achat vente metaux Montpellier - RICHARD RECUPERATION : recuperation metal,
Beziers, Herault, 34, recuperation metaux, vente metal, dechets fer
For new MoFo components I buy from Mouser most of the time.
Electronic components junk polution is serious ecological problem btw.
Go recycling 😉
In doing electrician job and we have always short pieces of copper or aluminium cables left overs
so we stock them and after urban local metal recycling point buy from us all metals parts.
Check your city metal recycling company and see if you can buy used heat sinks, copper wire and transformers
refurbished from machines you be surprised by the low cost and find good deal :
Achat vente metaux Montpellier - RICHARD RECUPERATION : recuperation metal,
Beziers, Herault, 34, recuperation metaux, vente metal, dechets fer
For new MoFo components I buy from Mouser most of the time.
Electronic components junk polution is serious ecological problem btw.
Go recycling 😉
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Yes, agree with you.
DIYA and others should start putting recycle symbol on PCB designs, if not already.
It would be a good start, isnt it.🙂
If you have an oscilloscope you can use a large capacitor and discharge it through the inductor with a low Ohm value power resistor in series, hook up scope probe over the resistor and then translate the scope curve into current, using the formula v(t) = L * di / dt the inductance can then be estimated. 🙂
I do simple visual inspection inside of Hammond 193V | 3A to verify diameter of the wire
and compare with inductor microwave wire diameter.
Look like microwave version have the same or very little less diameter.
I am not 100% sure about 2.5 A but it can handle 1.7~2A and stay safe.
Quality of the core lamination , sufficent quantity of inductance ?
Well let's try what happen anyway with cheap speaker and run MoFo with 19 V | 1.7A psu this night
and compare with inductor microwave wire diameter.
Look like microwave version have the same or very little less diameter.
I am not 100% sure about 2.5 A but it can handle 1.7~2A and stay safe.
Quality of the core lamination , sufficent quantity of inductance ?
Well let's try what happen anyway with cheap speaker and run MoFo with 19 V | 1.7A psu this night
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My pleasure Sir Lawrence
Yes, I am surprised You are right this choke made from microwave oven transformer sound perfect
for one MoFo psu 19V | 1.7 A bias build version.
Non saturation, nasty distortion etc. all is clean.
What I need now is find match 2 Ohm similar MOT for stereo.
Work like glue with other elements of actual audio system : Build This MoFo!
Thanks for discovering and funny good time on the bench
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My pleasure Sir Lawrence
Yes, I am surprised You are right this choke made from microwave oven transformer sound perfect
for one MoFo psu 19V | 1.7 A bias build version.
Non saturation, nasty distortion etc. all is clean.
What I need now is find match 2 Ohm similar MOT for stereo.
Work like glue with other elements of actual audio system : Build This MoFo!
Thanks for discovering and funny good time on the bench
Alright!
My version of this MoFo
I've listened to my MoFo for a couple of days now with a small output capacitor. So I can comment on this. 🙂
I'm driving the MoFo with a 6n6p SRPP tube preamp. Output impedance approx 1k. My speakers have an impedance of 8 ohm, and are easy to drive (very constant impedance and sensitive).
The power supply of the MoFo is a 18V toroid with a classic CRC capacitor bank (5 times 6800uf per channel). The DC voltage is around 23V. A Hammond 159ZC is used as source choke.
I have doubled the bias circuit (two pottis and also doubled the other 2 potti-connected resistors) and added a switch and 2 small 500k resistors between the gates and sources. This way I can switch between 2 Fets (keeping the non-used fet with the gate at source voltage). Both sources and drains are connected together. With the switch I control which gate gets a bias and the audio signal (two pole switch). I currently have a IRFP250 and an IXFK44N50 mounted. I am biasing both around 1.8 amps and I can just switch between both Fets with a small pop. 😱
The output capacitor is build from 5 times 680 uf Epcos Sikorel plus 5 times 2.2 uf ROE MKT and a small ROE MKP. So almost 3500 uf. Everything surplus (means dirt cheap).
I can't complain about the bass. With 8 ohm speakers this 3.5mf seems sufficient. The big Ixys part might be a bit fatter, but also a tiny bit darker (8000 pf vs 2000 pf). Differences between both fets are really small. Compared to my (bloody expensive) tube amp both are a bit darker. But this is caused by the tube amp I think (I have several amps and all less sparkling compared to my big tubes). The MoFo is really open. Little details are easy to spot (Amused to death). Music is just floating. But the big tube amp is projecting Roger Waters a bit further towards me. I don't know why. With the MoFo Roger is 50 cm in front of the speakers, with the tube amp he is 2 meters in front. But: the MoFo is a bit sharper (soundstage is more stable).
The MoFo is really quit. No hum. Damping is also nice (compared to tubes of course). Easy listening.
The MoFo is still fresh, and I have done this AB only once. It is also difficult because of the huge difference in gain (the tube amp needs a 100 times less input for the same output).
I've listened to my MoFo for a couple of days now with a small output capacitor. So I can comment on this. 🙂
I'm driving the MoFo with a 6n6p SRPP tube preamp. Output impedance approx 1k. My speakers have an impedance of 8 ohm, and are easy to drive (very constant impedance and sensitive).
The power supply of the MoFo is a 18V toroid with a classic CRC capacitor bank (5 times 6800uf per channel). The DC voltage is around 23V. A Hammond 159ZC is used as source choke.
I have doubled the bias circuit (two pottis and also doubled the other 2 potti-connected resistors) and added a switch and 2 small 500k resistors between the gates and sources. This way I can switch between 2 Fets (keeping the non-used fet with the gate at source voltage). Both sources and drains are connected together. With the switch I control which gate gets a bias and the audio signal (two pole switch). I currently have a IRFP250 and an IXFK44N50 mounted. I am biasing both around 1.8 amps and I can just switch between both Fets with a small pop. 😱
The output capacitor is build from 5 times 680 uf Epcos Sikorel plus 5 times 2.2 uf ROE MKT and a small ROE MKP. So almost 3500 uf. Everything surplus (means dirt cheap).
I can't complain about the bass. With 8 ohm speakers this 3.5mf seems sufficient. The big Ixys part might be a bit fatter, but also a tiny bit darker (8000 pf vs 2000 pf). Differences between both fets are really small. Compared to my (bloody expensive) tube amp both are a bit darker. But this is caused by the tube amp I think (I have several amps and all less sparkling compared to my big tubes). The MoFo is really open. Little details are easy to spot (Amused to death). Music is just floating. But the big tube amp is projecting Roger Waters a bit further towards me. I don't know why. With the MoFo Roger is 50 cm in front of the speakers, with the tube amp he is 2 meters in front. But: the MoFo is a bit sharper (soundstage is more stable).
The MoFo is really quit. No hum. Damping is also nice (compared to tubes of course). Easy listening.
The MoFo is still fresh, and I have done this AB only once. It is also difficult because of the huge difference in gain (the tube amp needs a 100 times less input for the same output).
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I don't know how many of you only have this amp stuck to the testbench, driving scopes and DMM's. But please connect this thing to a decent set of speakers. 🙄
This is one nice amp. Yesterday I have listened to it for a couple of hours, and it is really good. Big open soundstage. Music completely detached from the speakers. Rock solid imaging. No sibilance (and my speakers have titanium dome compression drivers).
It is the kind of amp you just keep turning the volume up (in stead of down). Not good for the wife/kids/neighbors.
Me happy 😀😀
This is one nice amp. Yesterday I have listened to it for a couple of hours, and it is really good. Big open soundstage. Music completely detached from the speakers. Rock solid imaging. No sibilance (and my speakers have titanium dome compression drivers).
It is the kind of amp you just keep turning the volume up (in stead of down). Not good for the wife/kids/neighbors.
Me happy 😀😀
Dear All,
Sorry I am asking same question again and again in other forums.
Can I use balanced out put or unbalanced output of headphone DAC.
Is the output from headphone DAC sufficient for MOFO ?.
Please let me know if it works I will build this.
I will listen low to mid volumes. I am using 20W 7.5 ohm CHR-70 (3rd-gen)speakers.
Thank you.
Sorry I am asking same question again and again in other forums.
Can I use balanced out put or unbalanced output of headphone DAC.
Is the output from headphone DAC sufficient for MOFO ?.
Please let me know if it works I will build this.
I will listen low to mid volumes. I am using 20W 7.5 ohm CHR-70 (3rd-gen)speakers.
Thank you.
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The normal MoFo is single ended. So unbalanced. If you would take the unbalanced output of your DAC, you have a 4.4Vpp max. That is equal to about 1.5 VRMS or 300 mW. That is not much.
I have a Allo Boss DAC that is capable of 2.1 VRMS (500 mW if used with the MoFo). It is good enough for normal volumes with my 88dB speakers. But I'm running it close to its maximum. So I really prefer a preamp.
In theory it might be possible to use the balanced output (and connect the minus to the earth). But this is only possible if both channels of the DAC are completely separated. I doubt if this is the case. I wouldn't do it.
You might consider a step-up transformer. If you can get one with a 1:4 ratio or something, that might work. You will have a really high capacitance so a low impedance at the input. But your headphone amp will have no problems with this. You could even drive this transformer balanced. 😎