ok will keep a look out for them.....
EDIT: after some searching, 500g rolls of 15awg are working out at almost €20 each, I would need 4, thats €80 total for an experiment. Too much I think! I'll search more to see can I find some cheaper, but thats the cheapest so far....
Fran
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since microwave transformers are free it might have been a decent idea to measure the L of the primary and secondary before cutting it open.
And after cutting it open, cutting it so that you can still use the lengthwise laminations is a good idea for cores on which to wind a nice inductor or two??
_-_-bear
Hi Randy
Greetings from Asbury, er... Clifton Park
Madisound always has good options for this sort of thing
this guy for instance
Steel Laminate 2.0 mH 15 AWG Inductors from Madisound
or this
Sidewinder 2.0 mH Air Core Inductor 16 AWG from Madisound
feeling sexy - buy this one
Solen 2.0 mH Perfect Lay Inductors 14 AWG from Madisound
Greetings from Asbury, er... Clifton Park
Madisound always has good options for this sort of thing
this guy for instance
Steel Laminate 2.0 mH 15 AWG Inductors from Madisound
or this
Sidewinder 2.0 mH Air Core Inductor 16 AWG from Madisound
feeling sexy - buy this one
Solen 2.0 mH Perfect Lay Inductors 14 AWG from Madisound
if one chooses to re-use an old transformer, as an inductor carrying DC current, then one must introduce an air gap into the core circulation route to reduce the saturation that would other wise occur.
This is generally easy if the laminations are bolted together.
Just place them all in the same direction and after inserting the bobbin place a couple of layers of paper over the ends of all the legs. Add on the I's and you have an air gapped (well paper gapped) EI inductor core suitable for DC use.
This is generally easy if the laminations are bolted together.
Just place them all in the same direction and after inserting the bobbin place a couple of layers of paper over the ends of all the legs. Add on the I's and you have an air gapped (well paper gapped) EI inductor core suitable for DC use.
The laminate core doesn't make the PS better - it makes the coils smaller and then they use less wire, so if you are making them yourself, then it is somewhat easier?
Actually the air core is technically superior - nothing to saturate.
In speakers it is better to use air core for that reason.
AndrewT, I was suggesting earlier that if you had to hacksaw a microwave transformer then cut it so that you keep the "fingers" from the "E" to wind coils around...
_-_-
Actually the air core is technically superior - nothing to saturate.
In speakers it is better to use air core for that reason.
AndrewT, I was suggesting earlier that if you had to hacksaw a microwave transformer then cut it so that you keep the "fingers" from the "E" to wind coils around...
_-_-
Chokes fore tube amp supply from Lundahl all seem to be 4H-20H
Saturation current range from 150-500mA
Obviously only to be used with high voltage/low current
I would like to know why tube builders use those huge chokes, and you suggest relatively small Xover aircore inductors
Tube filament chokes seems closer with 2-6 Amp ratings, but still huge induction
Is it due to tube builders usually trying to filter out hum issues, and we are at the opposite end trying to filter out high frequency noise
Or just a matter of different load impedance
Hmm, I suppose it should be calculated from the impedance its loaded in to
Which would be maybe a 0.47ohm source resistor ?
Oh, heatsink just arrived, its "hot"
Saturation current range from 150-500mA
Obviously only to be used with high voltage/low current
I would like to know why tube builders use those huge chokes, and you suggest relatively small Xover aircore inductors
Tube filament chokes seems closer with 2-6 Amp ratings, but still huge induction
Is it due to tube builders usually trying to filter out hum issues, and we are at the opposite end trying to filter out high frequency noise
Or just a matter of different load impedance
Hmm, I suppose it should be calculated from the impedance its loaded in to
Which would be maybe a 0.47ohm source resistor ?
Oh, heatsink just arrived, its "hot"
Attachments
Thanks to all for the help.
AndrewT: thanks for the link to the supplier - I'll be following up on that.
Bear: The MOT was huge, say a 6" cube at least and weighed a ton (from an industrial microwave). The laminations were welded so needed an angle grinder to open the seam. Once done though they came apart very easily and I have the laminations still. More research yet to be done...... I think this would be a lot simpler if I had gone the single supply route. But becuase I went dual mono, everythnig is doubled up. Actually it will be very interesting to hear the results in this setup.
Fran
AndrewT: thanks for the link to the supplier - I'll be following up on that.
Bear: The MOT was huge, say a 6" cube at least and weighed a ton (from an industrial microwave). The laminations were welded so needed an angle grinder to open the seam. Once done though they came apart very easily and I have the laminations still. More research yet to be done...... I think this would be a lot simpler if I had gone the single supply route. But becuase I went dual mono, everythnig is doubled up. Actually it will be very interesting to hear the results in this setup.
Fran
hammond also makes chokes that would be suitable like this one, 10mH 5A .16 DCR $24 USD
Hammond Choke 159ZJ
Hammond Choke 159ZJ
Yep, been a while since we went to NY Noise, or measured the bass scrubbing on Dead Cd's
Bob
I think the issue is that when you use it with another amp or compare it to another amp, the gain makes a difference in the subjective impression and in practical comparisons.
In my personal system right now I have a horn that gives me legit 109db/1w, and midbass drivers that do legit 98-99db/1w. Given that most "normal" amps are ~26db "gain" and this one is "15 db gain" you can do the math and see that for me this is a "magic match". I can run the F5 (if I had one) direct to the compression drivers and match to the rest of the system with no attenuators required.
The rest of you all are going to have to struggle to get enough voltage swing out of your opamp based preamp or DAC stage (if you use a passive pre or buffer...). Headroom is a consideration in my view for anything that uses an opamp or has limited output voltage swing in the driving or preamp position.
Of course a lot depends on who is driving what, how loud, and how big a room and with what sort of source material...
In my view using a relatively low power amp on relatively low sensitivity (read: normal speakers) in regular sized rooms at the average SPL in the seat of say 92-3dB SPL is going to give the F5 some headroom issues. If that was what I had to do I'd be thinking bridged myself...
Ymmv.
_-_-
In my personal system right now I have a horn that gives me legit 109db/1w, and midbass drivers that do legit 98-99db/1w. Given that most "normal" amps are ~26db "gain" and this one is "15 db gain" you can do the math and see that for me this is a "magic match". I can run the F5 (if I had one) direct to the compression drivers and match to the rest of the system with no attenuators required.
The rest of you all are going to have to struggle to get enough voltage swing out of your opamp based preamp or DAC stage (if you use a passive pre or buffer...). Headroom is a consideration in my view for anything that uses an opamp or has limited output voltage swing in the driving or preamp position.
Of course a lot depends on who is driving what, how loud, and how big a room and with what sort of source material...
In my view using a relatively low power amp on relatively low sensitivity (read: normal speakers) in regular sized rooms at the average SPL in the seat of say 92-3dB SPL is going to give the F5 some headroom issues. If that was what I had to do I'd be thinking bridged myself...
Ymmv.
_-_-
My AB monos are run at 30Vdc rails and are plenty powerful with normal speakers
Power supply, 500watt trafos and 2x 15.000uf Jensen 4-pole, ea
Yeah, normal gain
Once again, Nelson does state that Firstwatt amps are designed to be used with relatively sensitive 8ohm speakers
BA designs are made fore those of us here who wants a bit more power
Honestly, I reckon F5 and BA-2 will be my last SS amps
A last statement, the best of this eara
And they may be constantly changing "building stones" fore Nelsons future creativity
Nelson has stated his furture designs will use this same base
And I will build a Tubelab Simple PP, also a last statement before closing time
From then on, classD will rule
Power supply, 500watt trafos and 2x 15.000uf Jensen 4-pole, ea
Yeah, normal gain
Once again, Nelson does state that Firstwatt amps are designed to be used with relatively sensitive 8ohm speakers
BA designs are made fore those of us here who wants a bit more power
Honestly, I reckon F5 and BA-2 will be my last SS amps
A last statement, the best of this eara
And they may be constantly changing "building stones" fore Nelsons future creativity
Nelson has stated his furture designs will use this same base
And I will build a Tubelab Simple PP, also a last statement before closing time
From then on, classD will rule