why? because you dont know how to calculate what you need? thats a terrible reason to use a transformer. which will in one foul swoop kill the hard fought performance. yet again, better off not using the NTD1 at all (well maybe not that much worse off, depends on the transformer). Using a transformer does not absolve you from working out the correct capacitor value for the reflected secondary impedance
honestly, it really seems that a number of people did not think it through at all before deciding to build this design; especially given we have had this exact conversation a number of times reaching back to the first version boards.
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Qusp, just a quick question for ya and I hope it is not a stupid one...
Since this is a fully balanced output, would the DC offset if any be nulled at the receiving end if omitting the output caps? What would be the end result doing so?
Thanks
Do
haha not a stupid question, one better off asked than not. I already covered this long ago. the DC will cancel yes... somewhere ... but you need a crapload of headroom and a tough as nails amp. if its not cancelled before you add gain ... well ... think about how much DC that would mean after say 12-15db gain
then you would need your amp to be perfectly matched phase to phase and a fully balanced crossover. basically its not doable, unless you have a BAL-SE stage as the FE of your poweramp, so that the DC is cancelled there (with medium voltage devices, like to220 fets or something, small signal jfets wont cut it). otherwise you will add a heap of voltage and current gain, to end up with several hundred watts of common mode DC for the speaker to cancel, and thats IF you have that much headroom in your rails, which is a mighty big IF.
most amps will have their FE driven into clipping even before any gain is added.
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haha not a stupid question, one better off asked than not. I already covered this long ago. the DC will cancel yes... somewhere ... but you need a crapload of headroom and a tough as nails amp. if its not cancelled before you add gain ... well ... think about how much DC that would mean after say 12-15db gain
basically its not doable, unless you have a BAL-SE stage as the FE of your poweramp, so that the DC is cancelled there. oitherwise you will add a heap of voltage and current gain, to end up with several hundred watts of common mode DC for the speaker to cancel, and thats IF you have that much headroom in your rails, which is a mighty big IF.
Ooooh! ok
A new day without learning something new is a wasted day. Now I can go to bed!
I plan on using it on my B24 amplifier but I might use a balanced Pre in front of the amp. Just not sure yet... I will try to find the formula to calculate the correct amount for the caps and buy them.
Thanks!
Do
the B24 has a pretty large input impedance yeah? as it happens mate, I tried my NTD1 directly driving nattonrice's B24 and a set of revelator based Troelsgraven Ellam-98 2ways when I took it down for last years Sydney head-fi meet.
that build (AKD12P with first gen NTD1 and fifo) was using 4.7uf auricap || 0.47uf vcap cutf and I can tell you it was not lacking bass response. in fact those little 2 ways give out a surprising amount of tight bass.
why bother with a preamp?
these are his Ellams and his B24
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that build (AKD12P with first gen NTD1 and fifo) was using 4.7uf auricap || 0.47uf vcap cutf and I can tell you it was not lacking bass response. in fact those little 2 ways give out a surprising amount of tight bass.
why bother with a preamp?
these are his Ellams and his B24
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also, i'm not ashamed to admit Im a bit of a bassshead when it comes to my music, test albums were various Massive Attack, Shpongle, Tool, Trentmoller, NIN. because aside from liking such music on occasion I was specifically testing the revelators for bass response, to see if I should be planning a sub, as i'm building a slightly larger set of 2 ways using the 18W rather than the 15W. I left without any worries about the performance in that area.
I was specifically testing the revelators for bass response, to see if I should be planning a sub, as i'm building a slightly larger set of 2 ways using the 18W rather than the 15W. I left without any worries about the performance in that area.
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Qusp in case no one told you before, or you' are not intelligent enough to realize by yourself, you are irritating. And insulting. You may not like what I' m typing but that that doesn' t give you the right to respond like that. Now, stop being an ars, say something productive, or please don' t respond to me.
hahaha, you know whats irritating? having to answer the same bloody elementary questions over and over and over again in the same thread. questions you should have asked and answered for yourself before taking the build on.
if I let that irritation show, sorry i'm just human.
here, i'll post the calculator again
its an xls file, you'll have to add the extension, the forum doesnt let you attach .xls
if I let that irritation show, sorry i'm just human.
here, i'll post the calculator again
its an xls file, you'll have to add the extension, the forum doesnt let you attach .xls
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right, so somebody else can answer again, the question that has been answered over and over and over... that makes it sooo much better.
I finally managed to get the attachment to stick in the post on the previous page, its a calculator someone gave me many eons ago when I had no idea the importance of such things. you will need to plug in the values for impedance and capacitance.
it really is something you should learn how to do without the exel file though, it applies to every single stage where a capacitor couples a signal to something less than an infinite impedance, parasitics too. its a simplified calc, but if you are using a transformer, you have to add in the primary and secondary impedance of the TX and the winding ratio ie work out the reflected impedance, not as simple to solve as connecting the NTD1 directly to an amp.
btw: i'm completely aware that i'm abrasive, its deliberate in some cases that call for it...
I finally managed to get the attachment to stick in the post on the previous page, its a calculator someone gave me many eons ago when I had no idea the importance of such things. you will need to plug in the values for impedance and capacitance.
it really is something you should learn how to do without the exel file though, it applies to every single stage where a capacitor couples a signal to something less than an infinite impedance, parasitics too. its a simplified calc, but if you are using a transformer, you have to add in the primary and secondary impedance of the TX and the winding ratio ie work out the reflected impedance, not as simple to solve as connecting the NTD1 directly to an amp.
btw: i'm completely aware that i'm abrasive, its deliberate in some cases that call for it...
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Ok qusp - I guess we are in religious territory here ;-) no need to argue about that
Hey Anders Trentemøller - correctly spelled - just nitpicking back
i saw him in live concert with another dane Michael Simpson a couple of years back. That was my moment of bass explosion. The roof went of the building - fantastic concert. Sorry for off topic
hehe yeah I knew I was probably spelling that wrong/lazily, good catch.
I saw him/them at 'Family' in Brisbane in 2007 ('the last resort' tour). its a pity that a couple of his tracks that would be almost perfect system tests and are otherwise quite well produced, with a decent amount of light and shade, actually do clip very slightly. the recording that is; Always Something Better (his remix) was EPIC live!
I saw him/them at 'Family' in Brisbane in 2007 ('the last resort' tour). its a pity that a couple of his tracks that would be almost perfect system tests and are otherwise quite well produced, with a decent amount of light and shade, actually do clip very slightly. the recording that is; Always Something Better (his remix) was EPIC live!
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Here's a quick peek of my build... It is not the latest pics since I have added heatsinks to it.
Chassis will be done later. On a side note, has anyone modded an EXAU2I to add external power to it? If you have succeeded in doing so and it does make a difference in SQ please PM me.
I've already put in more than 30 hours of music and must say it is definitely the BEST I/V stage I have ever had for my BII!
Sounds really good
Ciao!
Do
Chassis will be done later. On a side note, has anyone modded an EXAU2I to add external power to it? If you have succeeded in doing so and it does make a difference in SQ please PM me.
I've already put in more than 30 hours of music and must say it is definitely the BEST I/V stage I have ever had for my BII!
Sounds really good
Ciao!
Do
A new run of these boards is now available!
Please see the following thread for details:
http://www.diyaudio.com/forums/soli...ble-here-bal-bal-se-se-lpuhp.html#post3516741
Cheers,
Owen
Please see the following thread for details:
http://www.diyaudio.com/forums/soli...ble-here-bal-bal-se-se-lpuhp.html#post3516741
Cheers,
Owen
Not easy. I did a partial job by lifting the two regs 1.2v & 3.3v and supplying external power. This leaves the front end still powered by USB.
Since using Ian's kit i have reverted back to full USB power as the improvement now is too insignificant.
Unless using Ian's fifo i would imagine the best thing for the EXA is applying external clocks and reclocking the outputs after the isolators.
Thanks for the feedback and the great pictures Do!
Your build looks excellent... very clean layout and a good choice in the EXAU2I
I know from experience that combo sounds superb
Cheers,
Owen
Thanks Owen,
I'll update the picture later on when the whole thing is in a chassis
Ciao!
Do
Are in trouble: (
When Buffalo is offline I have the following voltages:
Q1: 1.65V - 21.8V
Q3: 1.65V - 23.5V
Q2: 1.65V - 23.5V
Q4: 1.65V - 23.5V
AVCC Buffalo: 3.3V - 3.3V
When connecting Buffalo:
Q1: 1.65V - 21.8V
Q3: 0.8V - 45V
Q2: 0.8V - 45V
Q4: 0.8V - 45V
AVCC Buffalo: 2.4V - 3.3V
Zener are removed.
Any advice please!
When Buffalo is offline I have the following voltages:
Q1: 1.65V - 21.8V
Q3: 1.65V - 23.5V
Q2: 1.65V - 23.5V
Q4: 1.65V - 23.5V
AVCC Buffalo: 3.3V - 3.3V
When connecting Buffalo:
Q1: 1.65V - 21.8V
Q3: 0.8V - 45V
Q2: 0.8V - 45V
Q4: 0.8V - 45V
AVCC Buffalo: 2.4V - 3.3V
Zener are removed.
Any advice please!
Attachments
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