Thanks X! I was also a little surprised by the 6.5v drop. I need to do some more poking around with my DMM to see if I’m correct on that. I also have .33R at the CRC vs the .22R spec’d in the schematic so that’s shedding a bit of additional voltage as well. I’ll add another 1R resistor to my ladder and see how much voltage I get back. Otherwise I do like the idea of the 24v supply. I have a whole bunch of those laying around. 
Once I get the second channel together I plan to test a range of inductors. I also have some Hammond 159zc’s which are quite similar in spec to what NB is talking about. I’ll give those a try with my Lii Audio Crystal 10’s and see what sort of headroom and bass response I can get out of the whole system as a speaker amp. I am also very interested in listening through my HD6xx’s. Question about wiring for headphones. Can I tie the negative wires from both channels together at the headphone jack or will that be bad for the SMPS’s? I’m using a separate SMPS for each channel.
Once I get the second channel together I plan to test a range of inductors. I also have some Hammond 159zc’s which are quite similar in spec to what NB is talking about. I’ll give those a try with my Lii Audio Crystal 10’s and see what sort of headroom and bass response I can get out of the whole system as a speaker amp. I am also very interested in listening through my HD6xx’s. Question about wiring for headphones. Can I tie the negative wires from both channels together at the headphone jack or will that be bad for the SMPS’s? I’m using a separate SMPS for each channel.
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You’ve made awesome progress on the LuFo Lite Jwjarch! I’m very curious about those XO inductors. Looking forward to hearing your stereo listening impressions with speakers that are capable of playing low frequency.
dBel84,
Thank you for the LuFo Lite Mouser cart! Last I checked, everything was in stock. That doesn’t happen much these days
dBel84,
Thank you for the LuFo Lite Mouser cart! Last I checked, everything was in stock. That doesn’t happen much these days
Thanks X.
I have searched to try and find a more detailed spec for the inductance rating but have turned up a blank regarding the frequency.
JW's choke exploration sounds very helpful to the community.
Are you planning to sell the LuFo Lite PCBs or will you post the Gerbers?
Thanks Vunce! You just reminded me I needed to order another pair of ERSE 20mH inductors for the second channel. Thank you!
NB, I also have a pair of the infamous microwave oven transformers to test out in the circuit. All in good time.
I should also have mentioned that I am currently using LD1010D jfets from AliExpress in lieu of the beautifully matched pair of LU1014's from the group buy. I just couldn't bring myself to solder those into something just yet. The specs on the LD1010's are slightly different from the LU1014 but they seem to work just fine in the circuit. I'm wondering if there would be any optimizations to be made with the LD1010's that you can think of, X?
And good luck on your build dB!
NB, I also have a pair of the infamous microwave oven transformers to test out in the circuit. All in good time.
I should also have mentioned that I am currently using LD1010D jfets from AliExpress in lieu of the beautifully matched pair of LU1014's from the group buy. I just couldn't bring myself to solder those into something just yet. The specs on the LD1010's are slightly different from the LU1014 but they seem to work just fine in the circuit. I'm wondering if there would be any optimizations to be made with the LD1010's that you can think of, X?
And good luck on your build dB!
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I never even thought of ordering them directly from Erse. But if PE has them on stock that’s probably not a bad route of you can get free shipping.
NB,
I will offer these from my shop (for those who don’t want to by 5 boards or the hassle) but will also post the Gerbers once we finalize the design. These were meant to be a nice easy first Class A amp for the DIY community.
NB,
I will offer these from my shop (for those who don’t want to by 5 boards or the hassle) but will also post the Gerbers once we finalize the design. These were meant to be a nice easy first Class A amp for the DIY community.
Another option is 4 of these arranged in a square in series. They will probably eek out more than 40mH for about same price as 1 Erse 20mH. Basically a square toroidal with very large air gaps.
Dayton Audio 10mH 18 AWG I Core Inductor Crossover Coil
Dayton Audio 10mH 18 AWG I Core Inductor Crossover Coil
Hey Skip Pack. I just got a canceled order email back from ERSE.
I went through that order cycle twice before I connected with the woman who told be about the bobbin issue. I have two 20mh SQs on hand that I'll reserve for Lufo Lite, most likely. I ordered some Hammond 159ZG 15mh 250mohm, 4A chokes (from Digikey) for a power supply use where I would have bought Erse SQs if they were available at Erse website prices.
I measured a Triad C-56U Inductor
Not sure how meaningful the results are as it's only a cheap Ebay 'transistor tester' gadget? Resistance looks a bit high but if I just put a wire link across the gadget it gives a resistance of 0.73ohms so the choke resistance would seem to be closer to 1.2ohms - if that's correct I wouldn't need any additional load than the choke to achieve my target bias current.
Not sure how meaningful the results are as it's only a cheap Ebay 'transistor tester' gadget? Resistance looks a bit high but if I just put a wire link across the gadget it gives a resistance of 0.73ohms so the choke resistance would seem to be closer to 1.2ohms - if that's correct I wouldn't need any additional load than the choke to achieve my target bias current.
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This looks perfect for your application! Nice result.
Thank you for sharing. Do you know what brand of inductor this is? They look like Dayton? I guess coming from PE they would be Dayton but I don’t see Dayton branded 18.6mH inductors in stock. These are custom units for a specific XO I guess.
Thank you for sharing. Do you know what brand of inductor this is? They look like Dayton? I guess coming from PE they would be Dayton but I don’t see Dayton branded 18.6mH inductors in stock. These are custom units for a specific XO I guess.
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The crossover is a PE branded product. I couldn't find them separately on their site either.
100 Hz High Pass 8 Ohm Crossover
100 Hz High Pass 8 Ohm Crossover
I think the triad 30mH 2A dc 0.7ohm choke C56-U is cheaper at around 12€ at Mouser
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Assuming a 19v laptop brick as PSU and 1.5A bias current we are 28.5w per channel. Some of this is the 4v drop across the cap Mx and the balance is the Lu1014 and resistor.
Let’s say 30w and we don’t want more than 30C rise for 55C max heatsink temp.
30C/30W is 1C/W should be ok. So a 0.5C/W would be fine and run at about 40C assuming 25C ambient.
Let’s say 30w and we don’t want more than 30C rise for 55C max heatsink temp.
30C/30W is 1C/W should be ok. So a 0.5C/W would be fine and run at about 40C assuming 25C ambient.
I assembled the heatsinks and laid out the possible mounting points so that I could drill and tap the transistor mounts and brackets to hold the boards.
I plan to use a Vcor Flatpack smps for the power supply - hence my choice of less beefy capacitors on the board
close to first test but not quite there yet.
..dB
I plan to use a Vcor Flatpack smps for the power supply - hence my choice of less beefy capacitors on the board
close to first test but not quite there yet.
..dB