Lightspeed Attenuator

[Tripmaster]

Match.com

Inane in the membrane!

[Tony Moore]

Hi Leo,

Great post! You've got me wanting to try this.

I just wanted to ask though, how does this attenuator compare with a shunted Alps? (Shunt resistor say a Welwyn RC55Y)

Cheers,
Tony

[Tripmaster]

Hi

I have just roughly matched a set of LDRs using a 9v battery with a 1K resistor in series.



I plan to build a 5v supply and would like to measure the LDR resistance at different voltages to aid better matching.

Does anyone happen to know how much the 5 volt supply varies on a complete turn of a 100k pot? I have a feeling I’m going to kick myself when I see the reply!

Thanks

Richard

[leo]

Hi Leo,

Great post! You've got me wanting to try this.

I just wanted to ask though, how does this attenuator compare with a shunted Alps? (Shunt resistor say a Welwyn RC55Y)

Cheers,
Tony

Hi Tony,

I did like it better than my shunted Alps with the particular amp I tried it with, also I've only used standard metal film resistors for the shunt resistor, better quality types may turn it the other way, I really need to try some alternatives first to be sure

Music seemed to have more of that flow thing with the Lightspeed, sounded slightly more tidy in the highs (noticeable with cymbals )

[alb]

Thanks Leo.

I've tried swapping resistors on the shunted Alps and confess that i can't always tell the difference. So if you think the Lightspeed is preferable with basic metal films, then from my point of view at least, it's likely to be much the same whatever the resistor.

[Tony Moore]

Next project!

[leo]

Well its cheap enough to try a basic version, only niggle is it may take many more LDR's than needed to get a matched set

I'll try it with a few more amps when I get the time

[Tripmaster]

http://www.diyaudio.com/forums/showt...58#post1771358

Board for LDR's VCCS £60 built and tested + £3 P&P , bare pcb and application note £12 + £2.24 P&P
Board for IR transmitter and board for IR receiver, built modules (pair) £49.60 + £3 P&P, bare pcb and application note £13.77 + £2.27 P&P

Storm keypad £12.82 http://uk.farnell.com/storm-interfac...eys/dp/9809953

LDR's , matched or unmatched, I tried them unmatched because of the balance control Paul included with his version which works very well http://www.diyaudio.com/forums/showt...hreadid=148518
Or from Farnell £1.85 each http://uk.farnell.com/silonex/nsl-32...o-p/dp/3692218

Aluminum case was from Maplin, it was about 6 quid
Plastic case for transmitter was from Maplin, a few quid
Cable, battery clips etc from Maplin too

Details for a simple version without remote on vero http://diyaudioprojects.com/Solid/DI...ve-Attenuator/

Hi Leo

I think your Farnell link for the LDRs maybe wrong.

I think this is the right product, but this part number is missing an 'S' at the end.

http://uk.farnell.com/silonex/nsl-32...in_merch=true&

Here is the link to the DIYAUDIO thread

http://www.diyaudio.com/forums/showp...postcount=2421

Richard

[leo]

Hi Leo

I think your Farnell link for the LDRs maybe wrong.

I think this is the right product, but this part number is missing an 'S' at the end.

http://uk.farnell.com/silonex/nsl-32...in_merch=true&

Here is the link to the DIYAUDIO thread

http://www.diyaudio.com/forums/showp...postcount=2421

Richard

Ok ta, edited just incase infact it mentions the S for sorted and ideal for matching, can't seem to find the S on Farnell http://www.alliedelec.com/Images/Pro...ES_6993011.PDF

and for the non S

http://www.farnell.com/datasheets/102616.pdf

[Puffin]

I thought it might be of interest to others, that I have now built three of these as I bought 25 LDR's from Farnell and shared them with Tripmaster (I had 13, he had 12)

I have not found any major channel imbalance by just picking them randomly out of the bag. Any minor imbalance can be adjusted using the 1K trimmers.

I have some balanced LDR's on order (Diyaudio) They will cost me £20 for four. So it will be interesting to see if these make any difference.