Hey sek, thanks for your input - I hadn't seen those before, which led me to find this AES article from 2009 with some updated info as well.
All this lead to me wishing once again that I had the luxury of using gear to properly test for distortion...
PS I'm surprised at how unpopular OVP (over voltage protection) is for DIY gear line level inputs. opc please don't take this as a stab at The Wire - which I clearly think is pure genius.
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no need for LME envy if you're using the TPA6120
TPA6120 is a current feedback op amp, can have Vgain at nearly the same speed of the LME49600 @ Av=1 buffer
the TPA6120/THS6012 is speced with Working min current into 25 Ohm load of 400 mA - the LME only 250 mA, 400 mA is its short circuit limit
further the audio specs of the TPA6120 are superior to real # for the LME buffer
the LME datasheet specs aren't those of the buffer alone - they plot the THD for the buffer inside another low distortion op amp feedback loop
using the TPA6120 in a similar multiloop you can get even better numbers because you can have added local feedback gain around the TPA6120 inside the loop
I wouldn't use the TPA6120 directly for DAC I/V - I think the best on datasheet specs for audio DAC I/V right now is the ADA4897-1, although it has only +/-5 Vsupply max
I would consider the TI OPA1641 as the input/global feedback op amp around a TPA6120 for the headphone/line out
TPA6120 is a current feedback op amp, can have Vgain at nearly the same speed of the LME49600 @ Av=1 buffer
the TPA6120/THS6012 is speced with Working min current into 25 Ohm load of 400 mA - the LME only 250 mA, 400 mA is its short circuit limit
further the audio specs of the TPA6120 are superior to real # for the LME buffer
the LME datasheet specs aren't those of the buffer alone - they plot the THD for the buffer inside another low distortion op amp feedback loop
using the TPA6120 in a similar multiloop you can get even better numbers because you can have added local feedback gain around the TPA6120 inside the loop
I wouldn't use the TPA6120 directly for DAC I/V - I think the best on datasheet specs for audio DAC I/V right now is the ADA4897-1, although it has only +/-5 Vsupply max
I would consider the TI OPA1641 as the input/global feedback op amp around a TPA6120 for the headphone/line out
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do remember we arent talking about the lme in isolation here and honestly can you present an actual advantage of having 400ma vs 250ma for a headphone driver? the wire can easily be used directly as an iv stage, even a balanced one, but yeah unless you can find some pcbs that someone has spare youre out of luck.
if you need any tpa chips cheap you can have mine, i have 4 here i dont need because i prefer the wire =)
yep, which is how it would be used and how you are recommending the tpa be used =)
if you need any tpa chips cheap you can have mine, i have 4 here i dont need because i prefer the wire =)
http://www.diyaudio.com/forums/head...headphone-amplifier-pcbs-101.html#post2807354
OR
Attached to the build wiki -
"The Wire" Headphone Amp Build Wiki - diyAudio
OR
Attached to the build wiki -
"The Wire" Headphone Amp Build Wiki - diyAudio
Hi Vitop, yes all of the The Wire pcb's etc sold out a few months ago, including the leftovers...
I belive the Objective 2 would make for a good project for the two of you, it performs exceedingly well, is cheap and the build is very well documented.
I've got my O2 on holiday with me, but I do miss my Wire se-se...
Regards,
Paul.
I belive the Objective 2 would make for a good project for the two of you, it performs exceedingly well, is cheap and the build is very well documented.
I've got my O2 on holiday with me, but I do miss my Wire se-se...
Regards,
Paul.
I'm about to embark on my journey with "The Wire". I was lucky enough to acquire a rework board from a fellow diyAudio member and I'm at the point where I'm sourcing parts. I'm looking at this part as a replacement for C21, C26, C27, and C32...
810-CGA5L1X7R1E106K
...at Mouser.
The only difference that I can see is it's recommended for automotive applications. I'd assume this just means that the part can stand up to more abuse. Can I use this part instead of the general mlcc part in the BOM?
TIA!
Mull3t
810-CGA5L1X7R1E106K
...at Mouser.
The only difference that I can see is it's recommended for automotive applications. I'd assume this just means that the part can stand up to more abuse. Can I use this part instead of the general mlcc part in the BOM?
TIA!
Mull3t
why? is it cheaper? I doubt it, auto grade parts are usually more expensive. this one from Kemet is fine 581-12063C106KAT2A (mouser part #) or this for a bit less than the part you linked. but for whatever reason I tend to go with murata when I can so I would pay a little bit more for this one unless I was getting heaps.
Is there a sound quality difference between these 10uF multi layer X7R caps?
The 35V one may have a use for people making a Bal-Bal not on a board as I may or may not one day do. The current path with this type of circuit is from one plate of the cap through an LME49600 +ve power pin, out through the headphone, back in through the other LME49600 and out of it's -ve power pin, and back to THE OTHER PLATE OF THE SAME CAP. Not to earth in the middle or anywhere.
So by having one cap span the two LME chips power + pin and - pin (and another cap for the other LME's two -/+ power pins) you miss out from each current path two end plates, two solder joints and the via or bit of copper track and that might have an effect on the sound quality.
Also on The Wire Bal-Bal board the two 10uF's for each current path are in series so are effectively 5uF at double the voltage rating.
The 35V one may have a use for people making a Bal-Bal not on a board as I may or may not one day do. The current path with this type of circuit is from one plate of the cap through an LME49600 +ve power pin, out through the headphone, back in through the other LME49600 and out of it's -ve power pin, and back to THE OTHER PLATE OF THE SAME CAP. Not to earth in the middle or anywhere.
So by having one cap span the two LME chips power + pin and - pin (and another cap for the other LME's two -/+ power pins) you miss out from each current path two end plates, two solder joints and the via or bit of copper track and that might have an effect on the sound quality.
Also on The Wire Bal-Bal board the two 10uF's for each current path are in series so are effectively 5uF at double the voltage rating.
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Is there a sound quality difference between these 10uF multi layer X7R caps?
The 35V one may have a use for people making a Bal-Bal not on a board as I may or may not one day do. The current path with this type of circuit is from one plate of the cap through an LME49600 +ve power pin, out through the headphone, back in through the other LME49600 and out of it's -ve power pin, and back to THE OTHER PLATE OF THE SAME CAP. Not to earth in the middle or anywhere.
So by having one cap span the two LME chips power + pin and - pin (and another cap for the other LME's two -/+ power pins) you miss out from each current path two end plates, two solder joints and the via or bit of copper track and that might have an effect on the sound quality.
Also on The Wire Bal-Bal board the two 10uF's for each current path are in series so are effectively 5uF at double the voltage rating.
youre making my brain hurt =) seems a talent hehe
since this amp is very much a voltage source, i'm not sure how much impact the current path will have, over and above the voltage modulation. with the V1 Bal-se, I have played with using 0.47uf pps film caps bypassing polymer tantalum here, as well as just the film caps when mounted directly above my PSU, but for the bal bal so far i'm just using the stock build except for the lack of input resistors and only zfoil for FB/gain
It's not voltage but current that makes the voice coil in the headphone move back and forth according to Flemings rules for motors and generators.
The applied difference in potential across the load (aka the voltage) is merely a means of making some current flow. The current interacts with the fixed magnets causing a resultant mechanical deflection in a specific direction.
So the signal path is in reality the current path from one capacitor plate all the way to the other.
What an amplifier is doing is servo'ing a power supply across a load.
Depending on the size of the reservoir and the size of the loads current demand, the amplifier could be servo'ing the mains supply across the load.
In a dual rail single ended supplied system the path is earth referenced to the centre tap or earth star between the two capacitors, which discharge one at a time. But with balanced a more elegant solution is that the one capacitor discharges from both plates and the same time.
A disadvantage is that twice the voltage capacitor is required so for a high power class AB amplifier that's something a of a problem as they tend to stop at 100V. And for the The Wire Bal-Bal is a problem as the clean and fast sounding polymer caps have very small values above 16 volts and we need at least 30V.
I'm also still using all the stock values and parts on my Bal-Bal except I did tack on some Black Gates across the Nichicon polymers and they did what the always do which is give a big powerful slamming rocket bass that is a bit muddled and grainy. I did it because with the HD800's there was a very disappointing lack of bass with The Wire in place so I thought I give it a go to see what happened. Took about three minutes to fit them in situ at the back of the PC under the table, so if it had no effect I was not wasting much time.
My Bal-Bal is supplied by the 400 Watt SMPS the Seasonic X400 but through the motherboard, so that's probably not ideal. I had various ideas regarding feeding it direct using the wires that normally go to the Molex or SATA power feeds and traced some of the mobo to sound card connections in the PCI but there are a few and I have to reverse engineer it more extensively that I have so far.
I've not tried tacking on the Vishays yet. The sound card needs a different output stage first I think.
The applied difference in potential across the load (aka the voltage) is merely a means of making some current flow. The current interacts with the fixed magnets causing a resultant mechanical deflection in a specific direction.
So the signal path is in reality the current path from one capacitor plate all the way to the other.
What an amplifier is doing is servo'ing a power supply across a load.
Depending on the size of the reservoir and the size of the loads current demand, the amplifier could be servo'ing the mains supply across the load.
In a dual rail single ended supplied system the path is earth referenced to the centre tap or earth star between the two capacitors, which discharge one at a time. But with balanced a more elegant solution is that the one capacitor discharges from both plates and the same time.
A disadvantage is that twice the voltage capacitor is required so for a high power class AB amplifier that's something a of a problem as they tend to stop at 100V. And for the The Wire Bal-Bal is a problem as the clean and fast sounding polymer caps have very small values above 16 volts and we need at least 30V.
I'm also still using all the stock values and parts on my Bal-Bal except I did tack on some Black Gates across the Nichicon polymers and they did what the always do which is give a big powerful slamming rocket bass that is a bit muddled and grainy. I did it because with the HD800's there was a very disappointing lack of bass with The Wire in place so I thought I give it a go to see what happened. Took about three minutes to fit them in situ at the back of the PC under the table, so if it had no effect I was not wasting much time.
My Bal-Bal is supplied by the 400 Watt SMPS the Seasonic X400 but through the motherboard, so that's probably not ideal. I had various ideas regarding feeding it direct using the wires that normally go to the Molex or SATA power feeds and traced some of the mobo to sound card connections in the PCI but there are a few and I have to reverse engineer it more extensively that I have so far.
I've not tried tacking on the Vishays yet. The sound card needs a different output stage first I think.
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