Mauro Pensasa for President
...would be more appropriate!!!! Anyway, Ed is in the right groove - and I think we should all say a thanks to Mauro - the thread perhaps lingers on and eceeds 2k postings because the design has some real virtues??? There is still a chance to find out, simply build this thing!
@analog_sa and totally off topic: Take a look at the link:
http://www.lyraconnoisseur.com/files/3_2.png
Topless version of Lyra's line-amp, and I can spot a lot of wood but not so much aluminum.... Jonathan C. might have a reason doing it this way - beside mere looks - but I think it it is for looks. And yes, this can create issues with stray fields of other components in closer vicinity. The industrial designer surely did a nice job (front side at least) and the guts are no disappointment either.
And off topic once more: Vibration control should be a standard practice for pre-amps and expecially tube pre-amps.
Off topic mode ends here, I apologize... For RevC - it sounds like prayers I know: Painless and straightforward to build, rewarding SQ and NO REGRETS...
Cheers
Andre
...would be more appropriate!!!! Anyway, Ed is in the right groove - and I think we should all say a thanks to Mauro - the thread perhaps lingers on and eceeds 2k postings because the design has some real virtues??? There is still a chance to find out, simply build this thing!
@analog_sa and totally off topic: Take a look at the link:
http://www.lyraconnoisseur.com/files/3_2.png
Topless version of Lyra's line-amp, and I can spot a lot of wood but not so much aluminum.... Jonathan C. might have a reason doing it this way - beside mere looks - but I think it it is for looks. And yes, this can create issues with stray fields of other components in closer vicinity. The industrial designer surely did a nice job (front side at least) and the guts are no disappointment either.
And off topic once more: Vibration control should be a standard practice for pre-amps and expecially tube pre-amps.
Off topic mode ends here, I apologize... For RevC - it sounds like prayers I know: Painless and straightforward to build, rewarding SQ and NO REGRETS...
Cheers
Andre
...had to change over to IE5, as I get kicked out after about 1 minute of typing. No clue what this might be - the moderator watching us getting more and more off topic???
For a cast and CNC machined housing as seen in the attached pic - well one thing for sure it does add a HEAVY dollar charge on top of the product BOM cost. Not that this would play any role for products in the price class of a Lyra preamp. Net margin is going to be lowered a tiny bit, but one can still make a good living I suppose..... For those that demand the best, price plays a secondary role haha!
Of course the wooden enclosure looks more "organic" and maybe - thinking as a potential buyer - this implies a more analog sound....? If it wasn't to obtain a bettter sound quality, it surely makes a good score on the list of things to have for marketing.
And after the thread where Mr. Carr was starting to elaborate on JFETs and FETs deployed in his line stage came to an abrupt end -it seems I will now keep asking myself forever, how many similarities one could find in the works of Mr. E. Borbely and JC. Well, maybe it is time to check out a Borbely line stage - just to get a grip on the performance.
And off topic comes to an end. I think soon we'll hear a clear "shape up or leave"...
Bests
Andre
For a cast and CNC machined housing as seen in the attached pic - well one thing for sure it does add a HEAVY dollar charge on top of the product BOM cost. Not that this would play any role for products in the price class of a Lyra preamp. Net margin is going to be lowered a tiny bit, but one can still make a good living I suppose..... For those that demand the best, price plays a secondary role haha!
Of course the wooden enclosure looks more "organic" and maybe - thinking as a potential buyer - this implies a more analog sound....? If it wasn't to obtain a bettter sound quality, it surely makes a good score on the list of things to have for marketing.
And after the thread where Mr. Carr was starting to elaborate on JFETs and FETs deployed in his line stage came to an abrupt end -it seems I will now keep asking myself forever, how many similarities one could find in the works of Mr. E. Borbely and JC. Well, maybe it is time to check out a Borbely line stage - just to get a grip on the performance.
And off topic comes to an end. I think soon we'll hear a clear "shape up or leave"...
Bests
Andre
Feast or Famine!
I recently posted a problem of having full rail voltage to my 318...
I assumed that the problem was caused by a poor solder joint on the zenar.. So I ordered replacement parts from digikey,, and was very surprised to find a package in the mail from Brian containing replacement parts... (and an additional pair of rca's!)... Thank you very much...
I replaced the 318 and the zenars... taking perhaps excessive care to avoid any more cold solder joints... and was surpised to find that I now had only one or two volts at the 318... still putting out full negative rail at the output.
After much 'putzing' I could find no obvious faults.. and having an extra set of parts went ahead and replaced them once more... same situation... basically no juice to the 318.
The 'hot' side of the R1 and R4 both read at rail voltage... but down to a volt or less on the zenar side.
Hard to imagine that both sets of replacement parts are bad.. but I'm having trouble seeing where the juice is bleeding too.. Any guesses would be much appreciated...
thanks
steve
I recently posted a problem of having full rail voltage to my 318...
I assumed that the problem was caused by a poor solder joint on the zenar.. So I ordered replacement parts from digikey,, and was very surprised to find a package in the mail from Brian containing replacement parts... (and an additional pair of rca's!)... Thank you very much...
I replaced the 318 and the zenars... taking perhaps excessive care to avoid any more cold solder joints... and was surpised to find that I now had only one or two volts at the 318... still putting out full negative rail at the output.
After much 'putzing' I could find no obvious faults.. and having an extra set of parts went ahead and replaced them once more... same situation... basically no juice to the 318.
The 'hot' side of the R1 and R4 both read at rail voltage... but down to a volt or less on the zenar side.
Hard to imagine that both sets of replacement parts are bad.. but I'm having trouble seeing where the juice is bleeding too.. Any guesses would be much appreciated...
thanks
steve
Dead Short Somewhere
If you are dropping almost full rail voltage across the 1K resistors you have a short to ground somewhere. They are disapating right at 1 watt.
If your 318 is socketed, remove it and check again. If still dropping this much current it is either your zeners backwards or the caps are shorted. Either one should fail if powered up for very long. The caps should start to swell prior to bursting. The zener may just smoke.
The 1k resistors are protecting the supply traces right now, max current is about 35 ma.
Good luck!
George
steve said:
If you are dropping almost full rail voltage across the 1K resistors you have a short to ground somewhere. They are disapating right at 1 watt.
If your 318 is socketed, remove it and check again. If still dropping this much current it is either your zeners backwards or the caps are shorted. Either one should fail if powered up for very long. The caps should start to swell prior to bursting. The zener may just smoke.
The 1k resistors are protecting the supply traces right now, max current is about 35 ma.
Good luck!
George
'Made a list.... and checked it twice" Seriously, I have compared every single component on the board for value and orientation with the other working channel... and every component checks out... But the board did take a bit of a beating when I swapped out the lm318 and zenars.. and some of the traces are a little rough.. though they all look intact...
when I measure impeadance from the 1k resistor to ground I get about 1.5k...rising as the caps charge up... so there isn't a 'dead short' and I haven't found any particularly 'hot' spot either.. (Haven't left the amp on for long enough to find out either) both V12+ and V12- look pretty close to 1-2v relative to ground..
If the zenars are backwards... then they are marked backwards... I suppose that could happen... but seeing as how I replaced them and got the same results I'm inclined to think that the problem lies elsewhere. Just can't figure out where elsewhere is...
I'm guessing that the original fault fryed some other component... but I haven't a clue what could cause this particular phenomena...
Again, I'd appreciate any thunks you might have on this issue...
steve
when I measure impeadance from the 1k resistor to ground I get about 1.5k...rising as the caps charge up... so there isn't a 'dead short' and I haven't found any particularly 'hot' spot either.. (Haven't left the amp on for long enough to find out either) both V12+ and V12- look pretty close to 1-2v relative to ground..
If the zenars are backwards... then they are marked backwards... I suppose that could happen... but seeing as how I replaced them and got the same results I'm inclined to think that the problem lies elsewhere. Just can't figure out where elsewhere is...
I'm guessing that the original fault fryed some other component... but I haven't a clue what could cause this particular phenomena...
Again, I'd appreciate any thunks you might have on this issue...
steve
Another check
Look at the part number for the zeners to verify voltage. Any chance this are 1.2 volt and not 12 volt?
I matched my zeners in all three My_Refs. Used a pair of 12 volt batteries in series and a 1K dropping resistor and measured voltage across the zener. For 12 volt, all measured 12.2 - 11.8 volts.
You might want to check yours to be sure. Maybe try the ones from Brian just to be sure.
Also, sound like you have not socketed the LM318. Not so easy to swap out.
Get your meter and start checking versus the other board. You will have to charge up the caps, but you should be able to get up to 200K easy with the meter oriented the right way from + to - with time. Then with the correct meter orientation measure from neg to ground, and then from ground to positive. This will require more chaging as you are doubling the voltage across each rail. If you can charge up the caps and they hold it it has got to be your zeners. Even a bad LM318 will draw down the supply.
George
Look at the part number for the zeners to verify voltage. Any chance this are 1.2 volt and not 12 volt?
I matched my zeners in all three My_Refs. Used a pair of 12 volt batteries in series and a 1K dropping resistor and measured voltage across the zener. For 12 volt, all measured 12.2 - 11.8 volts.
You might want to check yours to be sure. Maybe try the ones from Brian just to be sure.
Also, sound like you have not socketed the LM318. Not so easy to swap out.
Get your meter and start checking versus the other board. You will have to charge up the caps, but you should be able to get up to 200K easy with the meter oriented the right way from + to - with time. Then with the correct meter orientation measure from neg to ground, and then from ground to positive. This will require more chaging as you are doubling the voltage across each rail. If you can charge up the caps and they hold it it has got to be your zeners. Even a bad LM318 will draw down the supply.
George
Finally figured it out....
When I first tested the amp I must have had a cold solder joint at one of the zenars.. this set the supply voltage to the 318 at about 32v this... toasted the 318.. but then must of sent >30 volts to the input of the 3886... no load... but it seems that it toasted the 3886 anyway...
Anyway, the toasted 3886 was sending -32v to pin 3 of the 318.. which toasted the 2 replacement 318's that I tried... and then bleed the supply voltage to the 318 down to +1 and -4v... When I looked at the supply voltage on the 318 with a scope I saw that the voltage started to return to normal as soon as I cut the power supply...
Anyway... I replaced both the 318 and the 3886 together and ...... it works!
Sounds pretty nice too... but it will take some listening to give it an honest call...
Thanks again...
When I first tested the amp I must have had a cold solder joint at one of the zenars.. this set the supply voltage to the 318 at about 32v this... toasted the 318.. but then must of sent >30 volts to the input of the 3886... no load... but it seems that it toasted the 3886 anyway...
Anyway, the toasted 3886 was sending -32v to pin 3 of the 318.. which toasted the 2 replacement 318's that I tried... and then bleed the supply voltage to the 318 down to +1 and -4v... When I looked at the supply voltage on the 318 with a scope I saw that the voltage started to return to normal as soon as I cut the power supply...
Anyway... I replaced both the 318 and the 3886 together and ...... it works!
Sounds pretty nice too... but it will take some listening to give it an honest call...
Thanks again...
supply voltage for 8 Ohm speaker
Hi all,
Somewhere I have read that the LM3886 power supply should be a +/- 28Volt supply for driving 4 Ohm Speakers. In the LM3886 datasheet I saw a figure "Clipping vs. Supply Voltage". With 4 Ohm speaker the clipping is higher when using voltages above
28 Volt.
But what does that mean? Occurs clipping only with high levels (> 30 Watt) or is clipping a problem with > 28 V supplies in general?
I would like to use the LM3886 in an active crossover. The bass chassis are 8 Ohm type (parallel = 4 Ohm), the tweeter is a 8 Ohm type. Which supply Voltage do you recommend for LM 3886, can I use for both +/- 35 V?
Arne
Hi all,
Somewhere I have read that the LM3886 power supply should be a +/- 28Volt supply for driving 4 Ohm Speakers. In the LM3886 datasheet I saw a figure "Clipping vs. Supply Voltage". With 4 Ohm speaker the clipping is higher when using voltages above
28 Volt.
But what does that mean? Occurs clipping only with high levels (> 30 Watt) or is clipping a problem with > 28 V supplies in general?
I would like to use the LM3886 in an active crossover. The bass chassis are 8 Ohm type (parallel = 4 Ohm), the tweeter is a 8 Ohm type. Which supply Voltage do you recommend for LM 3886, can I use for both +/- 35 V?
Arne
Re: supply voltage for 8 Ohm speaker
it means that with higher supply voltage clipping arose earlier (less power).
That is, on 4 ohm you actually got MORE power output if you use LESS supply voltage.
Less is more!
You can use the same, but I would use less. Besides, have you considered connecting the speakers in series? Than you could use the same 35V supply without problems, and probably will get better results sonically (smaller currents -> reduced chances of clipping due to 3886's "SpIKE" protection gettin' in the way + likely better spkr damping), at the price of about the same power "derating" of using 35V on 4ohm.
I would go for it if possible.
1543 said:
it means that with higher supply voltage clipping arose earlier (less power).
That is, on 4 ohm you actually got MORE power output if you use LESS supply voltage.
Less is more!
You can use the same, but I would use less. Besides, have you considered connecting the speakers in series? Than you could use the same 35V supply without problems, and probably will get better results sonically (smaller currents -> reduced chances of clipping due to 3886's "SpIKE" protection gettin' in the way + likely better spkr damping), at the price of about the same power "derating" of using 35V on 4ohm.
I would go for it if possible.
New layout.. New Thread...
I have produced some new PCBs and started a new thread here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=71675
I have produced some new PCBs and started a new thread here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=71675
After some months of reading this huge thread i decided to build a 5.1 amp for my pc and here it is:
The 2 rev_c is used for the 2 front chanels, the rev_a is for the rear chanels and one rev_c for the center. 300VA trafo for the fronts, 160VA for the center and 200VA for the rear chanels
The 2 rev_c is used for the 2 front chanels, the rev_a is for the rear chanels and one rev_c for the center. 300VA trafo for the fronts, 160VA for the center and 200VA for the rear chanels
