majkisk said:
This sort of sales information will have to be done off the forum with PM's, I don't think the moderators like it.
majkisk, I will have two in stock for immediate delivery in 2 days, one can be sent to Macedonia insured/air post for $50aud (30euro) or I can send it to your friends here in Australia.
Contact me with (PM below) with your email address and I will send some literature on the Lightspeed Attenuator to you.
http://www.diyaudio.com/forums/member.php?s=&action=mailform&userid=8370
or you can just email me at ( georgehifiatoptusnet.com.au ) substitute the at for @
Cheers George
Passive Pre Amp forum? Yes please.
Vote here for it, if you haven't already.
http://www.diyaudio.com/request/
Cheers George
Vote here for it, if you haven't already.
http://www.diyaudio.com/request/
Cheers George
Stuffed one this week.
I built one with a single 7812, and four CCS circuits. My plan is to use dual pots for mono volume control.
I have it all wired and have the connectors. Just need to install and finish the wiring. Since I have two units, it will be easy to compare to one with voltage control.
Also I will take a couple pictures of the circuit. Packed it all in a about a 3 x 3 inch area. With four CCS circuits it is pretty tight.
Hope there is no smoke on power up.
George
I built one with a single 7812, and four CCS circuits. My plan is to use dual pots for mono volume control.
I have it all wired and have the connectors. Just need to install and finish the wiring. Since I have two units, it will be easy to compare to one with voltage control.
Also I will take a couple pictures of the circuit. Packed it all in a about a 3 x 3 inch area. With four CCS circuits it is pretty tight.
Hope there is no smoke on power up.
George
I have to admit that I'm completely confused by the use of the CCS. If I understand correctly, the optocouplers vary their resistance as a function of current. As the datasheet says:
"The photocell resistance is high when the LED current is 'off' and low resistance when the LED current is 'on'". (emphasis mine)
So, how is it that a constant current source is useful? It seems to me that we should be using a constant voltage source feeding the LEDs wired in series with a variable (but equal) current. This may not totally eliminate the need for matching and/or trimming, but it seems to me to be the best way to use the devices.
I'm not questioning anyone's experience with the CCS versions. It just seems that I must be missing something. Can someone help me understand?
"The photocell resistance is high when the LED current is 'off' and low resistance when the LED current is 'on'". (emphasis mine)
So, how is it that a constant current source is useful? It seems to me that we should be using a constant voltage source feeding the LEDs wired in series with a variable (but equal) current. This may not totally eliminate the need for matching and/or trimming, but it seems to me to be the best way to use the devices.
I'm not questioning anyone's experience with the CCS versions. It just seems that I must be missing something. Can someone help me understand?
Hey guys,
ive been lurking for sometime now and will take the plunge on building my own as i have ordered some parts already. im a newbie with very limited experience. i have only built a couple of tube amplifiers. my questions are
Will they be compatible with my tube amplifier and cd player? i know this have been posted on previous posts but i do not know how to measure the input z of my amplifier and the output z of my cd player.
this is the amp that i built!
http://www.audiotropic.net/Projects/mmAudio.html
i plan on using a 6 volt sla battery. how do i drop the voltage to have an output of 5volt?
i apologize for the newbie questions.
thanks,
ivan
ive been lurking for sometime now and will take the plunge on building my own as i have ordered some parts already. im a newbie with very limited experience. i have only built a couple of tube amplifiers. my questions are
Will they be compatible with my tube amplifier and cd player? i know this have been posted on previous posts but i do not know how to measure the input z of my amplifier and the output z of my cd player.
this is the amp that i built!
http://www.audiotropic.net/Projects/mmAudio.html
i plan on using a 6 volt sla battery. how do i drop the voltage to have an output of 5volt?
i apologize for the newbie questions.
thanks,
ivan
tubo said:
Repace the 100k pot with a 100k resistor to ground and the Lightspeed will be fine, Any good CD player should be fine as far as output impedance goes, and they are always specified in the manufactures specs.
Just make all 4 100ohm resistors around 180ohm and you should be fine. with the 6vdc battery.
Cheers George
UnixMan said:
Ivan. it will work, and work well as I have three customers that are happy with the Lightspeed and their tube output cd players that are well over 1000ohm output impedance, it's just not the perfect impedance match marriage that you can get with solid state output, so don't be put off making one if you have a tube cd player.
You could always configure it to be a very nice low output impedance <200ohms tube stage by using a SLCF (super linear cathode follower) output stage, which is the best tube output stage I have ever heard, below is the circuit, you have to ask Allen Wright for the component values as I do not have the right to give them.
Cheers George
Attachments
He doesn't say what type of output is on his CD player, my comments were more to put him at ease because of what UnixMan said, just in case he was put off if he does have a tube CD player, and it stopped him building his own Lightspeed.
I'm all for encouraging everyone to build or buy their own, as it is so much better than any other form of passive or active preamp.
Cheers George
I'm all for encouraging everyone to build or buy their own, as it is so much better than any other form of passive or active preamp.
Cheers George