I did a quick FFT of the LuFoLite with halogen bulb today and as we can see, it resembles the output of a SE Class A amp with triode like behavior. There is only 2nd and 3rd order harmonic distortion and this is for driving a 10ohm dummy load to 1.0Vpp - a typical level for moderately loud playing on a headphone. The THD is about 0.21% and the 2nd harmonic is about 20dB higher than the 3rd harmonic. This is for 20v rail, 13v source and 12v at the lamp below the inductor with 1.63A bias current:
Attachments
Thanks for all the info on the LuFo Lite X.
I'm collecting parts to build one (and I'll include the latest halogen bulb mod). Just to check if I may.
I am planning to use a pair of Triad C-56U chokes I have available. They're rated at 35mH, 2Amp and 790mOhms - a little lower inductance and slightly higher resistance compared with your MOT, but I think the Triads will be fine for headphone listening.
The halogen bulb equates to a 7.2ohm resistor and with the choke that gives a total of about 8ohms so, with a 24V SMPS, I reckon the LU1014D current will be around 1.5A and a dissipation of circa 18W - do I have that about right?
I'm collecting parts to build one (and I'll include the latest halogen bulb mod). Just to check if I may.
I am planning to use a pair of Triad C-56U chokes I have available. They're rated at 35mH, 2Amp and 790mOhms - a little lower inductance and slightly higher resistance compared with your MOT, but I think the Triads will be fine for headphone listening.
The halogen bulb equates to a 7.2ohm resistor and with the choke that gives a total of about 8ohms so, with a 24V SMPS, I reckon the LU1014D current will be around 1.5A and a dissipation of circa 18W - do I have that about right?
I was getting g closer to 11w dissipation. In the LU1014d based on 7v drop across it at 1.6A. The bulb burns up most of the heat. It needs a shade frankly or too bright to live with. An interesting amp would have something like a jack on the chassis and one plugs in a 12v halogen lamp cord to a table lamp with shade of your choice.
Hi X. Just wondering if you considered a SuSyLu Lite - I thought it might be an interesting project? The only complexity would seem to be around the choke, finding something suitable off-the-shelf is unlikely so it may require a custom wind (but it should be smaller/cheaper than your SuSyLu chokes) but I'm also wondering about just using two standard chokes (like the Triad C-56Us I already have)?
Yes, you can use two standard chokes (not magnetically coupled). The distortion will be a tad higher and you can’t call it SuSy… anymore as there is no “super symmetry” from the coupled chokes. However, you could arrange two Erse 40mH speaker crossover chokes side by side and there IS significant coupling as Jwjarch found that the 40mH rating was boosted to like 56mH or something like that when they were side by side. This was discussed earlier in this thread.
Last edited:
( good memory )
For anyone who loves simple amps (~12 parts or less), I have a fun discussion thread here:
A Fistful of Solder
A Fistful of Solder
I have a question about selecting the R131, R132, X133 (X131, X132).
option A :
R131 - 3 x 3ohm 10w (dayton audio DPR10-3.0 3 Ohm 10 Watt Precision 1% Audio Grade Resistor) stack using X111,X112 stack helper board
option B :
R131 - 2 x 3ohm 10w (dayton audio DPR10-3.0 3 Ohm 10 Watt Precision 1% Audio Grade Resistor) stack using X111,X112 stack helper board
R132 - DNR-3.3 3.3 Ohm 10W Precision Audio Grade Resistor
Is proper these options?
Any other options?
option A :
R131 - 3 x 3ohm 10w (dayton audio DPR10-3.0 3 Ohm 10 Watt Precision 1% Audio Grade Resistor) stack using X111,X112 stack helper board
option B :
R131 - 2 x 3ohm 10w (dayton audio DPR10-3.0 3 Ohm 10 Watt Precision 1% Audio Grade Resistor) stack using X111,X112 stack helper board
R132 - DNR-3.3 3.3 Ohm 10W Precision Audio Grade Resistor
Is proper these options?
Any other options?
Attachments
I've order parts with the shared mouer shopping cart by dBel84 in this #84. Thank you @dBel84
C141 581-02013D223KAT2A is quite small .. so I will order 80-C1210C223KBR instead.
The shared Lufo amp mouser shopping carr by Vunce (#195 of Lufo amp thread) helps selecting molex connectors.
For C121, C125 instead of C216. C217, I will purchase 4 pcs Mudorf 2.2uF 450Vdc Mundorf MCap EVO Capacitor or 2.2uF 400Vdc Mundorf MCap MKP Classic Capacitor.
https://www.hificollective.co.uk/catalog/evo150-22uf-450vdc-mundorf-mcap-aluminium-p-9128.html
https://www.hificollective.co.uk/catalog/mkp240-22uf-400v-mcap-polypropylene-capacitor-p-8524.html
.... and... some progress.
C141 581-02013D223KAT2A is quite small .. so I will order 80-C1210C223KBR instead.
The shared Lufo amp mouser shopping carr by Vunce (#195 of Lufo amp thread) helps selecting molex connectors.
For C121, C125 instead of C216. C217, I will purchase 4 pcs Mudorf 2.2uF 450Vdc Mundorf MCap EVO Capacitor or 2.2uF 400Vdc Mundorf MCap MKP Classic Capacitor.
https://www.hificollective.co.uk/catalog/evo150-22uf-450vdc-mundorf-mcap-aluminium-p-9128.html
https://www.hificollective.co.uk/catalog/mkp240-22uf-400v-mcap-polypropylene-capacitor-p-8524.html
.... and... some progress.
If you can get an opamp and buffer to have a harmonic profile like this, then it would sound similar. But the SE Class A profile is different than an opamp. Some say, sweeter, more natural. But “better” is in eyes or ears of the beholder. The distortion THD is certainly much higher than an opamp, but that’s not the point.