There are plenty of '49990MAs available on eBay.
Also, there are numerous single channel op-amps that you can use that will work in the circuit.
Just watch out for excessive DC offset at the outputs with some bipolar op-amps. MEASURE it before plugging any phones into it.
The LME49990 certainly wasn't nothing special when it came to sound quality.
Glad to see T.I. discontinue it.
Hopefully, they'll do the same for the "dry sounding" LME49600/49610 someday.
could be, its the 10k resistor from the + input to ground. You would be hard pressed to tell the difference between any of the LME opamps. All of them have many 0's after the decimal. You can use a socket adapter and then try a bunch of different opamps. I had a bunch of the 22volt ones and they sound pretty good to me. I made a preamp out of the headphone amp and it was used extensively to check out a number of dacs and power amps at the diyOttawa 2016 event. The Wire was well received. Owen would have beeen proud but he was moving to San Diego.
Hi all. Can someone help me with wiring the transformer to the psu? I have this one on OPC's recommendation https://www.digikey.ca/product-detail/en/triad-magnetics/VPT24-1040/237-1325-ND/2090063
On the input it says to tie the blue to violet and grey to brown (so put either of these pairs on the line and neutral of the AC?)
And the output says for parrallel to tie the black to orange and red to yellow... or series red to orange... so how should I attach these 4 inputs to the psu inputs?
Thanks!
On the input it says to tie the blue to violet and grey to brown (so put either of these pairs on the line and neutral of the AC?)
And the output says for parrallel to tie the black to orange and red to yellow... or series red to orange... so how should I attach these 4 inputs to the psu inputs?
Thanks!
Whether you want parallel or series depends on if you want 12v or 24v from the transformer. I assume 12v, but you never know...
Parallel gets you 12v, series gets you 24.
this seems to describe wiring up a dual primary and dual secondary transformer.
Wiring up the dual windings needs care. That's why they spell out the instructions.
But before you do any more. Build and use your Mains Bulb Tester.
Yes, I'd like 12V, so parallel... what's confusing me is that the PSU has 4 individual AC inputs, in 2 pairs, so how am I supposed to connect the 2 wires (after they're tied) to the 4 inputs?
Thanks!
And thanks AndrewT, yes I should test first.
So ya it has 2 inputs, and 2 outputs. If you want series (24v) then you would tie the gray and violet together, then put the line and neutral to blue and brown. If you want parallel (12v) you put line into blue and violet, and neutral into gray and brown. This powers both coils the same. For the output, the black and orange wires go together and red and yellow go together. That would give you 12v input into the PSU from a 120v line source.
Right. But my question is on the actual wire psu board there are 4 inputs... so how do I connect the 2 tied 12v wires on the 4 inputs? Do I split them again to give 12V to each of the input pairs? Supply 12v to just one pair? I checked all the wire docs and pages but can't find any info about how to connect the 4 inputs.
Oh I gotchya. It looks like the secondaries (12v AC output from transformer) are actually not supposed to be tied together for the wire's PSU board. Looks like both sets of secondary wires go to their own inputs like the schematic here shows:
https://drive.google.com/file/d/0B3MLwB9mdXl2Z3N4WWh4MU93SW8/view
Just curious, what is the power requirements (current consumption) for The Wire SE-SE amp? I saw that a previous poster quoted 25VA 12VAC secondaries. In the past, I've used 10VA 15VAC secondaries and the amp works fine. I have a future build and accidentally bought 7VA 15VAC secondaries. In my future build, I'll be powering a Wire SE-SE at ±15VDC and plan on also using the same power supply to supply ±15VDC ≈70mA to another device. I'm thinking the 7VA trafo won't be enough for both, would 10VA be fine or should I go to 15VA for the supply?
It really depends on what type of headphone you are driving. Sensitive, high impeadance headphones like my Sennheiser HD600(300ohms) or Beyerdynamic t90(250ohm) will likely be adequately driven using a small 12-15v 10VA transformer. On the other hand if you are driving a pair of low impeadance orthos like Hifimans then you will want to step up to a larger transformer. Just my opinion, I'm sure others will chime in with more technical advice.
If you have a ClassA amplifier and it stays in ClassA, even on the highest current transients, then the headphone impedance does not affect the PSU current draw.
Lower impedance headphones may demand so much current that a push pull ClassA amplifier transistions into ClassB for the higher currents.
However those transients are so short lived that there is virtually no extra heating effect in the transformer.
Lower impedance headphones may demand so much current that a push pull ClassA amplifier transistions into ClassB for the higher currents.
However those transients are so short lived that there is virtually no extra heating effect in the transformer.
OK. Not sure what class The Wire is... I'd think not class A at least. Perhaps, I'm wrong.
But it sounds like going with 10VA is not a big deal here with supplying The Wire alone. My only concerns other than delivering enough current to both components - The Wire and a JG Filter - was keeping the size of the trafo down. 15VA vs. 10VA shouldn't bee much of a size difference.
But it sounds like going with 10VA is not a big deal here with supplying The Wire alone. My only concerns other than delivering enough current to both components - The Wire and a JG Filter - was keeping the size of the trafo down. 15VA vs. 10VA shouldn't bee much of a size difference.
How does "The Wire" compare to the likes of THX's amps? I need the quiestest amp for iems only!
https://www.google.com/search?q=thx+aaa+headphone+amplifier&num=50&rlz=1C1CHZL_enUS753US753&source=lnms&tbm=isch&sa=X&ved=0ahUKEwizstrj67LVAhVprFQKHUkXCWYQ_AUIDCgD&biw=1920&bih=926#imgrc=xxfw03Yhh5XHcM:
https://www.google.com/search?q=thx+aaa+headphone+amplifier&num=50&rlz=1C1CHZL_enUS753US753&source=lnms&tbm=isch&sa=X&ved=0ahUKEwizstrj67LVAhVprFQKHUkXCWYQ_AUIDCgD&biw=1920&bih=926#imgrc=xxfw03Yhh5XHcM:
Given that I intend on running the single-balanced Wire on a 17volt supply, and that the caps in the design are rated for a max 16Vdc, would it hurt if I were to use these caps?:
RNU1E331MDN1PH Nichicon | Mouser Nederland
The ESR is increased to 14 mOhms, but I think this might not be a problem.
RNU1E331MDN1PH Nichicon | Mouser Nederland
The ESR is increased to 14 mOhms, but I think this might not be a problem.