I'll add that mine ramps perfectly too. I was an earlier build. I'll pop the lid and just confirm what pot I used with my ALWSR 5V supply.
Happy New Year!
Jon
Happy New Year!
Jon
Thanks you for the kind responses. I think that the build is ok as it does work. Having a pcb usually make it hard for even me to screw it up. I may try using a different 100k log pot and see if I get similar results. I also have parts to make an additional one for a different project so will experiment and see how it turns out. Thanks again. Perhaps will have to make modifications to spouse.
Jack C
Jack C
LDR for phono loading
I have not visited the thread in awhile so this subject may have already been covered. Silonex optocouplers make excellent continuously variable load resistors in phono stage. This application is particularly interesting in a MM/MI phono stage. Though nominally specified for 47K load, MM/MI cartridges tend to sound best all over the map up to 200K load. A range of 50R-250K can be accurately controlled using a 5V regulator and three pots in series(2.5Mohm coarse, 500K medium, 25K fine). The 25K pot is useful in the 50R-700R range appropriate for MC. I am using Precision Electronics mini-pots from Digikey, which line up six in a row in a space about 4" long projecting through the top of my highly modified ARC PH-2 phono stage.
In this fully balanced phono stage I use one LDR connected between the cartridge signal phases, paralleled with two 470K fixed load resistors (total of 940K in fixed resistance) between the signal phases and ground. In a single-ended phono stage, one LDR would replace the stock 47K fixed resistor. For fixed resistors I use Caddock TF020-- which IMO the Silonex equals or surpasses in SQ.
To set LDR resistance I made a patch cord with XLR at phono input out to alligator clips to ohmmeter.
I have not visited the thread in awhile so this subject may have already been covered. Silonex optocouplers make excellent continuously variable load resistors in phono stage. This application is particularly interesting in a MM/MI phono stage. Though nominally specified for 47K load, MM/MI cartridges tend to sound best all over the map up to 200K load. A range of 50R-250K can be accurately controlled using a 5V regulator and three pots in series(2.5Mohm coarse, 500K medium, 25K fine). The 25K pot is useful in the 50R-700R range appropriate for MC. I am using Precision Electronics mini-pots from Digikey, which line up six in a row in a space about 4" long projecting through the top of my highly modified ARC PH-2 phono stage.
In this fully balanced phono stage I use one LDR connected between the cartridge signal phases, paralleled with two 470K fixed load resistors (total of 940K in fixed resistance) between the signal phases and ground. In a single-ended phono stage, one LDR would replace the stock 47K fixed resistor. For fixed resistors I use Caddock TF020-- which IMO the Silonex equals or surpasses in SQ.
To set LDR resistance I made a patch cord with XLR at phono input out to alligator clips to ohmmeter.
Lightspeed Remote Control
Hi jcon2,
I no longer use the standard issue hifi equipment hierarchy for gain structure as I have removed all unnecessary amplification stages from my system. Less is certainly more with this approach.
To explain,
My loudspeakers are open baffle, full range driver, line source arrays with all the drive units wired in parallel. This results in a load impedance of circa 0.75 ohms. Rather punishing for a normal power amplifier, designed to work into 4 or 8 ohms, but my amplifier is a simple Class A source follower constructed from a heavy-duty 400W IXYS depletion mosfet with a current source load using the same device type. This allows DC coupling, on a split rail supply, so no coupling capacitors are required in the signal path. The line arrays only require a few watts of power to deliver a full orchestral crescendo as they have an efficiency in the region of 105 dB for 1 watt at 1 metre and unlike normal loudspeakers the sound pressure level only falls at the rate of 3db per doubling of distance from the line source whereas normal loudspeakers tend to lose 6 dB per doubling of distance.
The net effect of using the above loudspeaker is that, in practice no voltage gain is required from the power amp, hence the simplicity. So I have set up George’s Lightspeed MkII configuration driving the source follower power amp, which, incidentally, is incredibly transparent and musical, as there is so little to get in the way of the signal.
Using the VCCS in my system, set up for a similar range suggested by Nelson Pass further back in this rather long thread, gives more than adequate control for my purposes. Any channel discrepancies are easily adjusted with the balance control. The range of operation can be adjusted by changing the range setting resistors in the VCCS so it is pretty adaptable in this respect and can be easily matched to the system requirements.
Interestingly when the control is set to minimum in my system the signal level is so low that it is virtually inaudible at the listening position. This may not be the case for a normal amplifier with voltage gain into high efficiency loudspeakers. At the other end of the scale the level steps are small enough to allow the required volume setting to be achieved easily.
The sources I use prior to the Lightspeed are an SD memory card player feeding an Altmann Attraction DAC both with heavily modified power supplies and a valve based phono stage with carefully configured gain stages to minimise the signal path.
I must try David Garretson’s phono stage loading technique with the VCCS as this will allow load changing via remote control from the listening seat.
Regards
Paul
Hi jcon2,
I no longer use the standard issue hifi equipment hierarchy for gain structure as I have removed all unnecessary amplification stages from my system. Less is certainly more with this approach.
To explain,
My loudspeakers are open baffle, full range driver, line source arrays with all the drive units wired in parallel. This results in a load impedance of circa 0.75 ohms. Rather punishing for a normal power amplifier, designed to work into 4 or 8 ohms, but my amplifier is a simple Class A source follower constructed from a heavy-duty 400W IXYS depletion mosfet with a current source load using the same device type. This allows DC coupling, on a split rail supply, so no coupling capacitors are required in the signal path. The line arrays only require a few watts of power to deliver a full orchestral crescendo as they have an efficiency in the region of 105 dB for 1 watt at 1 metre and unlike normal loudspeakers the sound pressure level only falls at the rate of 3db per doubling of distance from the line source whereas normal loudspeakers tend to lose 6 dB per doubling of distance.
The net effect of using the above loudspeaker is that, in practice no voltage gain is required from the power amp, hence the simplicity. So I have set up George’s Lightspeed MkII configuration driving the source follower power amp, which, incidentally, is incredibly transparent and musical, as there is so little to get in the way of the signal.
Using the VCCS in my system, set up for a similar range suggested by Nelson Pass further back in this rather long thread, gives more than adequate control for my purposes. Any channel discrepancies are easily adjusted with the balance control. The range of operation can be adjusted by changing the range setting resistors in the VCCS so it is pretty adaptable in this respect and can be easily matched to the system requirements.
Interestingly when the control is set to minimum in my system the signal level is so low that it is virtually inaudible at the listening position. This may not be the case for a normal amplifier with voltage gain into high efficiency loudspeakers. At the other end of the scale the level steps are small enough to allow the required volume setting to be achieved easily.
The sources I use prior to the Lightspeed are an SD memory card player feeding an Altmann Attraction DAC both with heavily modified power supplies and a valve based phono stage with carefully configured gain stages to minimise the signal path.
I must try David Garretson’s phono stage loading technique with the VCCS as this will allow load changing via remote control from the listening seat.
Regards
Paul
@ georgehifi
FYI, back in 1981 this type of attenuation was used by AKAI in their cassette deck GX-F51, for recording fade-in / fade-out. It was a stereo device, with one LED and 2 LDR in one big black capsule, about 2 cm long. The code is MCD-7213P. I only have the GX-F31 model which does not have this device. No relevant Google search can be obtained. You can download the service manual from HiFi Engine | Download Free User/ Service Manuals, Amplifier, Receiver, CD, Tape, Tuner, Video, where I uploaded it.
FYI, back in 1981 this type of attenuation was used by AKAI in their cassette deck GX-F51, for recording fade-in / fade-out. It was a stereo device, with one LED and 2 LDR in one big black capsule, about 2 cm long. The code is MCD-7213P. I only have the GX-F31 model which does not have this device. No relevant Google search can be obtained. You can download the service manual from HiFi Engine | Download Free User/ Service Manuals, Amplifier, Receiver, CD, Tape, Tuner, Video, where I uploaded it.
Intersesting, my first Lightspeeds back in the mid 70's were 2 x camera lightmeter photo cells mounted in the ends of a tube that was the same diameter as the cells and a neon lamp (I don't think leds were bright enough then otherwise I would have used them) inserted into the middle of the tube as the lightsource, this was a stereo setup with one light source, And the way the calibration between the two channels were done was to push one of the cells further up the tube, closer to the light source.
This was Lightspeed Mk1 in configuration (series resitor shunt photocell) but was very prone to channel drift on different temperature days, but showed every one who heard it what a passive contactless pre was capable of driving my then new Sugden P51 poweramp instead of my Sugden matching C51 preamp with Quad ELS57's for speakers.
Cheers George
This was Lightspeed Mk1 in configuration (series resitor shunt photocell) but was very prone to channel drift on different temperature days, but showed every one who heard it what a passive contactless pre was capable of driving my then new Sugden P51 poweramp instead of my Sugden matching C51 preamp with Quad ELS57's for speakers.
Cheers George
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lightspeed configuration for balanced audio
Hi George and the rest of you,
I would like to make a Lightspeed for use with balanced audio and I'm looking for a description/schematics of how to wire this. I have been searching and reading this thread for several hours and I know the information is here but I still cannot find it...... I'm hoping that it can be done by wiring together two single ended modules.
Could somebody please point me to a post number or in any way help me.
Sorry for disturbing and have a nice weekend.
Cheers,
Nic
Hi George and the rest of you,
I would like to make a Lightspeed for use with balanced audio and I'm looking for a description/schematics of how to wire this. I have been searching and reading this thread for several hours and I know the information is here but I still cannot find it...... I'm hoping that it can be done by wiring together two single ended modules.
Could somebody please point me to a post number or in any way help me.
Sorry for disturbing and have a nice weekend.
Cheers,
Nic
There you go good luck on the matching of all the ldr's, and use a dual pot instead of this single as in the standard single ended version, as there will be too much current flowing through it for a single pot.
Cheers George
Attachments
shunt style balanced attenuator for less matching headaches
A fixed series/variable shunt style balanced attenuator can be done with one optocoupler per channel to minimize the required matching.
Yes this is the Lightspeed Attenuator MKI configuration, you will not get the same sound dynamicaly as the Lightspeed Attenuator MKII, also the minimum volume will be way to loud for most on the MKI.
Cheers George
It seems the Russian's are just as bad as the Chinese for copying ideas and names
It seems the Russian's are just as bad as the Chinese for copying ideas and even using the name in their ads, here is the Myth. Have they no scruples.
No wonder I get the ****'s when people ask can they do kits and such, I wish I'd never released the details on how to DIY build the Lightspeed Attenuator. Now all the scammers are comming out of the woodwork.
I should have kept going the way I was 5 years ago keeping it quiet and resin potting each one so nobody could find out.
MYTH - Lightspeed preamplifier
Cheers to the faithfull Diyer's and a the plague on the scammers
George
It seems the Russian's are just as bad as the Chinese for copying ideas and even using the name in their ads, here is the Myth. Have they no scruples.
No wonder I get the ****'s when people ask can they do kits and such, I wish I'd never released the details on how to DIY build the Lightspeed Attenuator. Now all the scammers are comming out of the woodwork.
I should have kept going the way I was 5 years ago keeping it quiet and resin potting each one so nobody could find out.
MYTH - Lightspeed preamplifier
Cheers to the faithfull Diyer's and a the plague on the scammers
George
Member
Joined 2002
I could have told you this too, i have seen so many rip off ideas and things on ebay, its sick.! ITS ACTUALLY really sad, the chinese, see a item they buy it copy it MASS PRODUCE It for 1/16th the price and make millions. ITS SICK.! Its the same with R/c cars or real car parts, cheap mad CRAP! thats why when you invent something you never release the schematic, and you wipe the numbers and data information off the components inside 🙂
Jase
TRUST ME i hear your rant!
I think they might even have the B1 buffer by NP in there. At least they seem to have done the Microprocessor code.
But once you put your stuff "out there" there is not much one can do. Except market your product very well. Maybe your angle should be...get an original by the inventor. Or buy homegrown.
copycat
I must correct you... Sadly it's my countryman from Serbia not Russia 🙁
http://www.diyaudio.com/forums/solid-state/129723-lightspeed-attenuator-input-selector.html
I must correct you... Sadly it's my countryman from Serbia not Russia 🙁
http://www.diyaudio.com/forums/solid-state/129723-lightspeed-attenuator-input-selector.html
Whatever country, does not make it right!!!!
I have sent him an email asking him to remove any reference to the word "Lightspeed" as he has on his website and manual and whatever else.
Please to all those faithful to the Lightspeed Attenuator cause, send him and email ( office@myth.rs ) to show your disapproval of how he is marketing and trying to scam on the Lightspeed name, and show it in a post here as well, this sort of IP rip-off has to be reprimanded.
Cheers George
I have sent him an email asking him to remove any reference to the word "Lightspeed" as he has on his website and manual and whatever else.
Please to all those faithful to the Lightspeed Attenuator cause, send him and email ( office@myth.rs ) to show your disapproval of how he is marketing and trying to scam on the Lightspeed name, and show it in a post here as well, this sort of IP rip-off has to be reprimanded.
Cheers George
George,
Dont you remember when this guy was on the forum asking questions about how to build the Lightspeed? From recollection I either noted it on the forums later that he had started Myth or emailed you although I dont recall which I did.
Just had an email conversation about this guy on Nov 25th with my Canadian friend. He asked me if I had heard of Myth Audio before and gave the link. My response was
"I remember when that guy was asking questions about how to build the lightspeed and then goes off and starts this company. I dont have any problem with it except he claims the concept was entirely his, which I know for a fact it wasnt, and he uses the Lightspeed name. Thats pretty bogus."
Dont you remember him George?
I agree that him using the Lightspeed name is c**p.
There is no defense for that.
Uriah
Dont you remember when this guy was on the forum asking questions about how to build the Lightspeed? From recollection I either noted it on the forums later that he had started Myth or emailed you although I dont recall which I did.
Just had an email conversation about this guy on Nov 25th with my Canadian friend. He asked me if I had heard of Myth Audio before and gave the link. My response was
"I remember when that guy was asking questions about how to build the lightspeed and then goes off and starts this company. I dont have any problem with it except he claims the concept was entirely his, which I know for a fact it wasnt, and he uses the Lightspeed name. Thats pretty bogus."
Dont you remember him George?
I agree that him using the Lightspeed name is c**p.
There is no defense for that.
Uriah
Hi Uriah, I'm pushing ?? and some things go over my head, I get so many emails to do this and that, I think this one may have slipped under the radar, this guy SUCKS big time, "sorry it must be that time of the month" but this scammer has really got under my skin. Not even any reference to how he got it, didn't even ask to use the Lightspeed name, which I would have said a definte NO to.
Cheers George
Cheers George
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Thats pretty crap George. Heres where Nelson (who seems to have lawyers to frighten the sh!t out of people) gets them to contact the guy and ask him "nicely" to cease and desist.
That option ain't open to many though. Pressure from us here on the forum is the least we can do.
Oh yeah, his price is a lot more than yours too.....
Fran
That option ain't open to many though. Pressure from us here on the forum is the least we can do.
Oh yeah, his price is a lot more than yours too.....
Fran