Anyone had any success matching up enough pairs of LDRs for 6 channels? How many devices did you start with to get 6 pairs? I think I've got twenty LDRs but that wont be nearly enough, I'm sure.
jeff mai said:
Jeff, apparently the NSL32sr2"S" is now sold to customers as the same batch letter A B C D E or F which the term "S" selected should have been in the first place.
What I heard was that some "knucklehead" at Allied Electronics in the warehouse was getting the grouped NSL's from Silonex in separate selected letter packages, but then was opening all of them and chucking them all in one box, and thus mixing them all up again.
I believe this now has be sorted out and offending "knucklehead" booted up the ****. So now we may get proper sorted ones with the same group letter when we purchase, "I hope"
Cheers George
Hi George,
After wrestling with equipment choices, I bought a an NHT Xd system. You can read a review of it at:
http://nhthifi.com/2006/press/reviews/new/AustralianHiFiXdOct2005.pdf
The key specs that affect the usage of a LightSpeed are an input impedance of only 10kohms with a sensitivity of 1.5V RMS. The CD player will be using an LC Audio ZAPfilter Mk2 that has an estimated output impedance of approximately 100 ohms and an output level of at least 2V RMS (the modder I would be using thinks that it will be between 2 and 3V RMS).
Will an LS work with this setup? If not, is it possible to wire the LS directly into the circuit of the ZAPfilter, thereby maintaining its low output impedance? Here is the circuit layout for the ZAPfilter:
http://lcaudio.com/images/ZapFilter/zf2dia.gif
What other options do I have?
Thanks and regards, Peter
After wrestling with equipment choices, I bought a an NHT Xd system. You can read a review of it at:
http://nhthifi.com/2006/press/reviews/new/AustralianHiFiXdOct2005.pdf
The key specs that affect the usage of a LightSpeed are an input impedance of only 10kohms with a sensitivity of 1.5V RMS. The CD player will be using an LC Audio ZAPfilter Mk2 that has an estimated output impedance of approximately 100 ohms and an output level of at least 2V RMS (the modder I would be using thinks that it will be between 2 and 3V RMS).
Will an LS work with this setup? If not, is it possible to wire the LS directly into the circuit of the ZAPfilter, thereby maintaining its low output impedance? Here is the circuit layout for the ZAPfilter:
http://lcaudio.com/images/ZapFilter/zf2dia.gif
What other options do I have?
Thanks and regards, Peter
abq-pete said:
Hi Peter, the Zapfilter II I have been playing around with also, in conjunction with the Harman Kardon HD970, in current mode with this incredible CD player/ DA Converter.
The Zap II will drive anything, it has a very strong output stage, and it's discrete and pure class A as well.
It has no trouble driving the Lightspeed with a 50K poweramp input, but 10k I think it will have trouble with, you may be able to raise the input impedance of the XDA if it is discrete fet or fet opamp input, if so you should be able to raise it safely to 50 or even 100K, but double check this with the manufacturer.
Cheers George
George,
Thanks for taking the time to reply and sorry for my slow response. I have been trying to get an answer from NHT but have not been successful. I am going to assume that they are not going to tell me how, let alone allow me to modify the XdA and keep my warranty.
There seems to be a formula that you use to determine the impact of these impedance mismatches. Can you share how to calculate the reponse curve of a source with output impedance 'A', the LightSpeed impedance 'B', and an amp with input impedance 'C' equals roll off at frequency 'D'.
Thanks and regards, Peter
Thanks for taking the time to reply and sorry for my slow response. I have been trying to get an answer from NHT but have not been successful. I am going to assume that they are not going to tell me how, let alone allow me to modify the XdA and keep my warranty.
There seems to be a formula that you use to determine the impact of these impedance mismatches. Can you share how to calculate the reponse curve of a source with output impedance 'A', the LightSpeed impedance 'B', and an amp with input impedance 'C' equals roll off at frequency 'D'.
Thanks and regards, Peter
Hi Peter. There is no "said" formula to work on, you should have a strong low source output impedance (cd player/or dac) of say less than 50ohm.
Then the minimum amp input impedance that I recommend after some A/B ing with our Audio Society is 50K no less for the Lightspeed to see, 100k or more is preferable, but all the members could not pick the 50K but all did pick that 30K was detrimental to the sound.
Cheers George
Then the minimum amp input impedance that I recommend after some A/B ing with our Audio Society is 50K no less for the Lightspeed to see, 100k or more is preferable, but all the members could not pick the 50K but all did pick that 30K was detrimental to the sound.
Cheers George
Help with details
I found this thread via another site and have tried to read as much of the original thread as I can. However I have to be honest and say it is so long and many of the technical parts go way over my head so could i ask for a little help please ?
I use a Theta Data Basic Transport and Cambridge DAC which I currently use with a 100K 24 stepped attenuator which has Vishay metal film resistors in to a Krell KSA50 (original type with pure class A non of the later bias plateau class A)
I seemed to get the impression that most seperate DACs will fulfill the low impedance source needed but what is the impedance on my Krell. Reading the thread I would guess it was 47k but would like to be sure.
Will the Lightspeed work in this case ?
I found this thread via another site and have tried to read as much of the original thread as I can. However I have to be honest and say it is so long and many of the technical parts go way over my head so could i ask for a little help please ?
I use a Theta Data Basic Transport and Cambridge DAC which I currently use with a 100K 24 stepped attenuator which has Vishay metal film resistors in to a Krell KSA50 (original type with pure class A non of the later bias plateau class A)
I seemed to get the impression that most seperate DACs will fulfill the low impedance source needed but what is the impedance on my Krell. Reading the thread I would guess it was 47k but would like to be sure.
Will the Lightspeed work in this case ?
Hi George... any way of redesigning to half input impendance for amps? I was thinking doubleing up the LDRs in parallel... for half the impendance.
Re: Help with details
The KSA50 circuit i have shows 23k input resistance. Obvioulsy not very suitable for your attenuator. In any case there is no reason to use such a high attenuator value unless your source uses poorly implemented tubes.
bencat said:
The KSA50 circuit i have shows 23k input resistance. Obvioulsy not very suitable for your attenuator. In any case there is no reason to use such a high attenuator value unless your source uses poorly implemented tubes.
Re: Re: Help with details
I aggree, a 100K pot is only suitable for very high input impedence power amps, such as some tube power amps like Rogue Audio, which are 1mohm (1,000K),
Nordic that has been discussed before, the matching would be very hard, better/easier to raise the input of the poweramp
Cheers George
analog_sa said:
I aggree, a 100K pot is only suitable for very high input impedence power amps, such as some tube power amps like Rogue Audio, which are 1mohm (1,000K),
Nordic that has been discussed before, the matching would be very hard, better/easier to raise the input of the poweramp
Cheers George
Matching a Krell KSA 50
Well you have managed to advise me that the pot I am using is not suitable but my message was a typing error and should have read 10K not 100K.
Still that was not the point it would seem that 23 k is the input impedance ( by the way if you could let me have a copy of the circuit diagram that would be fantastic) so will this work with the Lightspeed ?
If not is there anyhting I could do to make the two items more compatible ?
Regards
Bencat
Well you have managed to advise me that the pot I am using is not suitable but my message was a typing error and should have read 10K not 100K.
Still that was not the point it would seem that 23 k is the input impedance ( by the way if you could let me have a copy of the circuit diagram that would be fantastic) so will this work with the Lightspeed ?
If not is there anyhting I could do to make the two items more compatible ?
Regards
Bencat
you could reduce the value of the pot controling the LED's
50K might work
or even 25K
downside is LED life may be shortened.
cheers
mike
50K might work
or even 25K
downside is LED life may be shortened.
cheers
mike
Bencat - you have the Krell KSA-50, correct?
I have two Lightspeeds - one finished and the other on hold until I finish my Krell KSA-50 Clone.
I have been thinking of raising the input impedance of the Krell from 23k to 47k or higher - was just going to post on the Krell thread when I saw yours here...
I have two Lightspeeds - one finished and the other on hold until I finish my Krell KSA-50 Clone.
I have been thinking of raising the input impedance of the Krell from 23k to 47k or higher - was just going to post on the Krell thread when I saw yours here...
Re: Matching a Krell KSA 50
bencat, john65b, You can raise the input impedance of the Krell, simply by changing the input loding resistor to ground to 100K instead of 22K (R13), but the amp should not be turned on without the Lightspeed being attached, other wise the dc offset may go too high. This is how I run one of my bipolar input amps with the Lightspeed and it's never sounded so good.
Cheers George
bencat said:
bencat, john65b, You can raise the input impedance of the Krell, simply by changing the input loding resistor to ground to 100K instead of 22K (R13), but the amp should not be turned on without the Lightspeed being attached, other wise the dc offset may go too high. This is how I run one of my bipolar input amps with the Lightspeed and it's never sounded so good.
Cheers George
Sorry guys, also input filter cap (C4) should be changed to 100pf when using the Krell with the Lightspeed, so as not to cut into the top end ( -3db @ 200khz).
If the 470pf is left in it will be (-3 @ 42khz) which is a bit low for airy extended sounding highs.
Cheers George
If the 470pf is left in it will be (-3 @ 42khz) which is a bit low for airy extended sounding highs.
Cheers George
Anyone have some spare matched optocouplers they are willing to sell?
I also asked the same question in the Trading Post forum but no replies so far.
http://www.diyaudio.com/forums/forumdisplay.php?s=&forumid=2
I also asked the same question in the Trading Post forum but no replies so far.
http://www.diyaudio.com/forums/forumdisplay.php?s=&forumid=2
I doubt I can hear anything over 12khz (no joke). The Krell Clone I am finishing has a 680pf cap...is there a problem with high end rolloff here with the lightspeed?
john65b said:
A Lightspeed or even a passive 20K pot will be around 7k ish, that combined with series 1k R14 resistance give you around 8k.
An 8k resistance with 680pf to ground is a low pass filter which will roll off at -3db already at 30khz, at 15khz it is still down -1.5db.
So when using this Krell with a Passive Volume Control or a Lightspeed you should be lowering the input cap C4 to around 100pf. to keep the HF roll off above 50khz. This makes for airier faster sounding highs, instead of dull muted ones, mind you having extension in the top end can also be harsh if something in the system is not behaving itself (distortions oscillations and such)
Cheers George
Hi
my Lightspeed built from August rested some time behind my rack not connected because of active alternatives. A friend visited me 2 weeks ago and we heard some CDs which we both know. My friend remarked a lack of bass fundament in some songs that he first expected in a failure of the speakers. I could well explain that the speakers normally deliver enough base. I expected the guilty one in the preamp. I changed the preamps and plugged in the Lightspeed. The sound was more realistic with the right portion of bass. But there was a unbalanced sound.
After that I measured the output L/R with my PC and found a difference of about 4dB between R and L. The reason: I spared the trim pot. After soldering the trim pot the balance is now about +/- 0,3 dB. Sound quality is very nice.
The curious thing: the best sound is between 11 and 1 o'clock of the pot. At too low levels the sound is somehow compressed and not so lifelike.
What's the reason?
my Lightspeed built from August rested some time behind my rack not connected because of active alternatives. A friend visited me 2 weeks ago and we heard some CDs which we both know. My friend remarked a lack of bass fundament in some songs that he first expected in a failure of the speakers. I could well explain that the speakers normally deliver enough base. I expected the guilty one in the preamp. I changed the preamps and plugged in the Lightspeed. The sound was more realistic with the right portion of bass. But there was a unbalanced sound.
After that I measured the output L/R with my PC and found a difference of about 4dB between R and L. The reason: I spared the trim pot. After soldering the trim pot the balance is now about +/- 0,3 dB. Sound quality is very nice.
The curious thing: the best sound is between 11 and 1 o'clock of the pot. At too low levels the sound is somehow compressed and not so lifelike.
What's the reason?
Tolu said:
This why they invented a switch called a "Loudness Switch" for active preamps, it's a natural deficiency that happens between low level music and the human ear.
CHeers George