There is no clean solution to your BAL-SE co version requirement, but if I were you, I would lean towards one if the active IC based options like the INA137.
Better yet, I'll send you a prototpye PCB for a fully balanced LM3886 amp with your order, and you can just build that
Regards,
Owen
Great work Owen
I'd like to build one of these, but I cannot find much availability of the LME49990. Some sites say it's discontinued and TI don't hold any stock.
I did see Farnell have some but at around $10 US per IC, it's pretty pricey!
Any thoughts?
Hi tfboy,
Take a look at post 15 for some alternative (and sometimes better) options to the LME49990.
The LT1028 would be you best choice for MM or MC.
Regards,
Owen
And thanks to a post by Sabrosa in another thread: The Wire - All Boards and Kits Explained Here!
It's beautiful, and sounds beautiful too. Extremely quiet despite the high gain on LOMC Benz Micro cart. Love the accuracy of the bass, makes my old Project Tubebox II SE sound like mush. Cheers Owen!
Cool, neat work!
Is that an ADC beside it? Don't recognise that design ... could you tell us more about it? Looks like discrete opamp front end? Is there a story behind the upside down oscillator!?
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Thank you,
Yep its an ADC, a Beis AD24QS based on a CS5381.
The stock clock was generated by an mk2703b using a jellybean 27mhz crystal. I simply yanked all of that and put a Vanguard 24.576 TXCO in its place. There was really nowhere else to place it so I stuck it on with some sticky foam tape so it wouldn't short anything out.. The only shortcoming is the board no longer supports outputting anything but 96/192, but I only ever use 96 for ripping/playing vinyl anyhow.
The stock design simply used a single 12V input and used an inverter IC to produce the negative supply rail. It simply didn't supply enough current for the quad Sparko opamps so I modded the board to accept a typical +/- 12V supply rail, eliminating the inverter altogether though you can still see the 8 pin DIP slot where it used to be. Also had to install an op-amp buffer on the bottom of the board as biasing (quiescent) current (originally generated by the ADC chip itself) was insufficient for the quad Sparko's.
It is inherently a balanced design throughout, despite the stock layout only accepting RCA inputs, however the differential pairs are there to trivially tap into, no need to buy the XLR addon board that Beis also sells. Overall the ADC board can be improved from the stock design rather easily. I do wish it was more DIY friendly however, such as external clock input, bipolar supply input, screw terminals, etc rather than a final product that simply runs off a wall wart.
Schematic: http://www.beis.de/Elektronik/ADDA24QS/Images/AD24QS_sp.GIF
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“Hello, Is anybodyOut there...” I’m getting back into vinyl and just found thisthread. Not sure if anyone is still looking at it but I’ll give ita go.
First off, thank youOPC for sharing this elegant design.
I’d like to buildthis but had a few questions:
1) Can I still ordera PCB by updating the spreadsheet?
1a) If I can, do Ineed to wait till enough people request it to do a group buy?
1b) If I can’torder through the spreadsheet, is it available elsewhere?
2) The LME49990 thatthis is based on is obsolete. In post 15 the LT1028 is recommendedas a replacement which is available The LME part lists “NC”on pins 1, 8, and 5 but on the LT pins 1 and 8 are input offsetvoltage trim points and pin 8 is a “Frequency Over-Compensation”control pin. Are these pins NC on the PWB such that they can be usedfor their intended purposes?
Thanks in advance.
Bob
First off, thank youOPC for sharing this elegant design.
I’d like to buildthis but had a few questions:
1) Can I still ordera PCB by updating the spreadsheet?
1a) If I can, do Ineed to wait till enough people request it to do a group buy?
1b) If I can’torder through the spreadsheet, is it available elsewhere?
2) The LME49990 thatthis is based on is obsolete. In post 15 the LT1028 is recommendedas a replacement which is available
The LME part lists “NC”on pins 1, 8, and 5 but on the LT pins 1 and 8 are input offsetvoltage trim points and pin 8 is a “Frequency Over-Compensation”control pin. Are these pins NC on the PWB such that they can be usedfor their intended purposes?Thanks in advance.
Bob
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Why not try an Xono, I bought mine from Frank. I use MM only and it's very quiet and was significantly better than the Rega Aria and Boozehounds Jfet running on batteries.
Xono Renovatio
Xono Renovatio
Hi guys,
I'm very interested in this, looking to maybe create my own boards from the schematic (Owen if this is not allowed please let me know). I wonder if anyone can help explain what's the use of the 0.01uF and 1uF capacitors for C12-16 and C18 respectively? I believe these are low pass capacitors am I right? Any reasons why are the values used 1000v and 250v? The reason I ask this is because the places that I can order from is Digikey/Farnell/RadioShack.. Mouser is a headache due to tax/shipment.
I'm very interested in this, looking to maybe create my own boards from the schematic (Owen if this is not allowed please let me know). I wonder if anyone can help explain what's the use of the 0.01uF and 1uF capacitors for C12-16 and C18 respectively? I believe these are low pass capacitors am I right? Any reasons why are the values used 1000v and 250v? The reason I ask this is because the places that I can order from is Digikey/Farnell/RadioShack.. Mouser is a headache due to tax/shipment.
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