George,
I spent a whole day -Sunday- played with the attenuator with a groups of good ears after I replaced all those rectifiers to UF4007.
We all started to like this little monster. It sounds quite neutral without any coloration and smooth. It sound very open and it's good especially on live music. The bass is extraordinary outstanding and it mixes really well with the mids. The highs are smooth too, but too smooth and it makes the highs not that identical, therefore we have a feeling the highs aren't in line with the whole spectrum.
Thanks so much for your sharing the design and gulding me along. Next step I'll try making two step regulated PSU like yours.
I might put another dual 100KA for the other channel to make it a mono control.
Albert
I spent a whole day -Sunday- played with the attenuator with a groups of good ears after I replaced all those rectifiers to UF4007.
We all started to like this little monster. It sounds quite neutral without any coloration and smooth. It sound very open and it's good especially on live music. The bass is extraordinary outstanding and it mixes really well with the mids. The highs are smooth too, but too smooth and it makes the highs not that identical, therefore we have a feeling the highs aren't in line with the whole spectrum.
Thanks so much for your sharing the design and gulding me along. Next step I'll try making two step regulated PSU like yours.
I might put another dual 100KA for the other channel to make it a mono control.
Albert
albertli said:
The highs are what is commented about most with Lightspeed users, as being natural, dynamic, free of grain transparent, are some of the adjectives used, I dare say you have a H/F roll off happening, for you to make this comment, because of one of the following from post 1400, or your tube output of your Audio Note Dac is not up to driving the load
> And also another time when the interconnect from Lightspeed to power amp had too much capacitance, over 500pf and the input filter cap in the amp was over 200pf.
This combined capacitance of 700pf can give a high frequency roll off with the Lightspeed output resistance of 7kohms -3db @ 30khz or worse if there are more series resistances at the input of the power amp, need to see the input circuit<
Cheers George
Krzysztof,
The output impedance will be varied according to the input voltage supply. We suppose have to adjust the output impedance as close as possible so to make the output at balance level. ( same output volume level at both channels )
George,
I just pluged my CD when the time we had the listening test.
Please check the attached power amp. schematic which was used
during the listening test.
The output impedance will be varied according to the input voltage supply. We suppose have to adjust the output impedance as close as possible so to make the output at balance level. ( same output volume level at both channels )
George,
I just pluged my CD when the time we had the listening test.
Please check the attached power amp. schematic which was used
during the listening test.
Attachments
Power Supply
Albert,
A couple ideas I got after looking over your pictures. I like a small value, medium ESR right on the output of a 3 pin reg. Try the 56 ufd you have on the LED's. Too high a value cap, or an ultra low ESR can make the reg act up.
Also, and I hate to say this, the signal wiring you used looks a little suspect. I prefer solid core for signal, but at least use the same wiring for input and output. Wire quality can get comments from it is everything, to it is not audible. I like several cheap, small ga, copper wires. XLO chassis, Vampire CC, and Cardas magnet wire are all excellent and a dollars worth would wire the entire LS clone.
Lastly, you might consider a better quality circuit board. Some really like the phenolic type used, FR-2 I think. I prefer the fiberglass, FR-4 or whatever.
If the quality of your normal components includes the CAT and AN dac, spring for a 4.00 USD circuit board, a dollars worth of signal wiring, and decent quality RCA's.
I used to have a CAT Sig II, maybe 12 -15 years ago. Loved it. It was a very good preamp. The phono is why I sold it, just not enough gain, and did not want to use transformers or a headamp for normal MC cartridges.
And I like having dual volume controls. And the current limiting resistors need to be doubled in value because the current is only half. Mine works great with doubled 250k stereo pots to make a 125k mono pot. Ends up around 10K.
George
Albert,
A couple ideas I got after looking over your pictures. I like a small value, medium ESR right on the output of a 3 pin reg. Try the 56 ufd you have on the LED's. Too high a value cap, or an ultra low ESR can make the reg act up.
Also, and I hate to say this, the signal wiring you used looks a little suspect. I prefer solid core for signal, but at least use the same wiring for input and output. Wire quality can get comments from it is everything, to it is not audible. I like several cheap, small ga, copper wires. XLO chassis, Vampire CC, and Cardas magnet wire are all excellent and a dollars worth would wire the entire LS clone.
Lastly, you might consider a better quality circuit board. Some really like the phenolic type used, FR-2 I think. I prefer the fiberglass, FR-4 or whatever.
If the quality of your normal components includes the CAT and AN dac, spring for a 4.00 USD circuit board, a dollars worth of signal wiring, and decent quality RCA's.
I used to have a CAT Sig II, maybe 12 -15 years ago. Loved it. It was a very good preamp. The phono is why I sold it, just not enough gain, and did not want to use transformers or a headamp for normal MC cartridges.
And I like having dual volume controls. And the current limiting resistors need to be doubled in value because the current is only half. Mine works great with doubled 250k stereo pots to make a 125k mono pot. Ends up around 10K.
George
George,
I just hooked up my CD player direct to the LDR last week. It was working good and the sound spectrum was balance.
I did couple tweak yesterday with the double volume pot to control the L/R channels. I also had the psu converted into 2 steps, first to 12v then to LT1085-CT-5 to 5v with Blackgate 33uf and 470uf FK.
I found I have better control with 2 pots and the background is very dark that none of my preamp can compare. The boby of the sound is full / smooth and neutral without any fatique. I could imagine what the wonderful world would be after the blackgate breaking in. One thing too bad is I don't know how to use the commercial language to express my feeling to the sound.
Panelhead-George,
Thanks so much for your recommandation.
The wires for input ( voltage and analoge ) are magnet wires with telfon tubing. I have 6N 20g single copper wire for analoge out.
I certainly would put a better board for the LDR.
Please do tell me more on why I should put a 200R for current limiting? and what brand do the best for you?
Thanks
I just hooked up my CD player direct to the LDR last week. It was working good and the sound spectrum was balance.
I did couple tweak yesterday with the double volume pot to control the L/R channels. I also had the psu converted into 2 steps, first to 12v then to LT1085-CT-5 to 5v with Blackgate 33uf and 470uf FK.
I found I have better control with 2 pots and the background is very dark that none of my preamp can compare. The boby of the sound is full / smooth and neutral without any fatique. I could imagine what the wonderful world would be after the blackgate breaking in. One thing too bad is I don't know how to use the commercial language to express my feeling to the sound.
Panelhead-George,
Thanks so much for your recommandation.
The wires for input ( voltage and analoge ) are magnet wires with telfon tubing. I have 6N 20g single copper wire for analoge out.
I certainly would put a better board for the LDR.
Please do tell me more on why I should put a 200R for current limiting? and what brand do the best for you?
Thanks
Attachments
albertli said:
Good to see all is working good now albertli, I too would like to hear what Krzysztof asked, as one of my customers had the Convergent SL-1 Ultimate MkII and sold it once he got the Lightspeed Attenuator, and his friend sold his Matise Reference once he got his Lightspeed.
Cheers George
George, Krz,
I did pay all my attention to the lightspeed lately and would like to tweak it to it's best before the comparison. I certainly would love to do the compare, but have to be fair to the lightspeed. It needs some more time to break in.
All active preamp or power amp rely on too many parts to make them sound good, so there is chance we hear lots of coloration from those components. Our ears have been customly polluted since day one we got into music, so it is hard to teach our ears to listen to something true/ nuetral. I always compare my amprefiers with true instruments, like guitar, violin and trumpet so to tell myself what is real and what's not.
The lightspeed has minimum components to dirty the sound coming from the source, so I believe the only thing to blame is the recordings if I found the sound is not acceptable.
I'll keep working on it and patiently wait for the blackgate to work.
Albert
I did pay all my attention to the lightspeed lately and would like to tweak it to it's best before the comparison. I certainly would love to do the compare, but have to be fair to the lightspeed. It needs some more time to break in.
All active preamp or power amp rely on too many parts to make them sound good, so there is chance we hear lots of coloration from those components. Our ears have been customly polluted since day one we got into music, so it is hard to teach our ears to listen to something true/ nuetral. I always compare my amprefiers with true instruments, like guitar, violin and trumpet so to tell myself what is real and what's not.
The lightspeed has minimum components to dirty the sound coming from the source, so I believe the only thing to blame is the recordings if I found the sound is not acceptable.
I'll keep working on it and patiently wait for the blackgate to work.
Albert
99% there
My suggestions might seem to be a waste of time. The LDR's are very revealing, and a simple setup is very good.
The reason I mentioned using 200R resistors for current limiting is because you have gone to dual mono voltage control pots. The current is half of what it is with a stereo control, so the resistance needs to increase to keep the maximum current through the LDR the same.
5 volt supply, - 2.5 volts for the LDR gives 2.5 volts to control the current. If 100 ohm resistors were used with a mono pot, the maximum current would be 2.5 volts /100 ohms or 25 ma. The LDR will take it, but might shorten the life. Increasing the value of the resistor to 200 ohms will hold the current to 12.5 ma, this will last a lot longer.
George recommends leaving the pot in the middle when not using. I had some switched pots, but did not like the tracking as much as what I use now. Less control at low volume. I currently use a 125K log, and it works great for dual mono, the volume pots track really well.
Several have recommended a couple easy power supply tweaks. One is to bypass the LDR with a low ESR cap. Second to choke couple the regs to the LDR. Third run a constant current supply instead of a constant voltage.
Tried all three, but never got my CCS supply to work as well for some reason. I think it was my problem, not design. But someone broke into my car and got that board and other goodies. So sticking with tracking regs, 1 mH chokes to filter reg output and 10 ufd caps in parrel with LDR's.
Unless I just have to use an amplifier with a low input impdeance I cannot see going back to active.
One small change I recommend for your setup is to move the 470 ufd BG from the output of the 5 volt reg. I you have another 33 ufd, put it between the 12 volt and 5 volt regs. Then maybe the 470 ufd on the input of the 12 volt.
Small chokes are hard to find, a 0.5 - 5 mH choke with a ohm or two of DCR will make up for the falling performance of the 3 pins regs at higher frequency. 3 pin regs suffer degrading S/N at the top of the audio band.
I am not even getting everything out of mine compared to the commercial Lightspeed. I cannot give up source selecting. So all of miine have a source selector. George sez that once you try it without, there is no going back. Have not tried it, too lazy to plug and unplug.
George
My suggestions might seem to be a waste of time. The LDR's are very revealing, and a simple setup is very good.
The reason I mentioned using 200R resistors for current limiting is because you have gone to dual mono voltage control pots. The current is half of what it is with a stereo control, so the resistance needs to increase to keep the maximum current through the LDR the same.
5 volt supply, - 2.5 volts for the LDR gives 2.5 volts to control the current. If 100 ohm resistors were used with a mono pot, the maximum current would be 2.5 volts /100 ohms or 25 ma. The LDR will take it, but might shorten the life. Increasing the value of the resistor to 200 ohms will hold the current to 12.5 ma, this will last a lot longer.
George recommends leaving the pot in the middle when not using. I had some switched pots, but did not like the tracking as much as what I use now. Less control at low volume. I currently use a 125K log, and it works great for dual mono, the volume pots track really well.
Several have recommended a couple easy power supply tweaks. One is to bypass the LDR with a low ESR cap. Second to choke couple the regs to the LDR. Third run a constant current supply instead of a constant voltage.
Tried all three, but never got my CCS supply to work as well for some reason. I think it was my problem, not design. But someone broke into my car and got that board and other goodies. So sticking with tracking regs, 1 mH chokes to filter reg output and 10 ufd caps in parrel with LDR's.
Unless I just have to use an amplifier with a low input impdeance I cannot see going back to active.
One small change I recommend for your setup is to move the 470 ufd BG from the output of the 5 volt reg. I you have another 33 ufd, put it between the 12 volt and 5 volt regs. Then maybe the 470 ufd on the input of the 12 volt.
Small chokes are hard to find, a 0.5 - 5 mH choke with a ohm or two of DCR will make up for the falling performance of the 3 pins regs at higher frequency. 3 pin regs suffer degrading S/N at the top of the audio band.
I am not even getting everything out of mine compared to the commercial Lightspeed. I cannot give up source selecting. So all of miine have a source selector. George sez that once you try it without, there is no going back. Have not tried it, too lazy to plug and unplug.
George
Hi George,
I have the Orions am wondering if your Lightspeed Attenuator can work properly with my ATI AT6012 amp and the rest of the system components. Please comment. Thanks.
http://www.linkwitzlab.com/orion_us_specs.htm
http://www.linkwitzlab.com/orion_asp.htm
I have the Orions am wondering if your Lightspeed Attenuator can work properly with my ATI AT6012 amp and the rest of the system components. Please comment. Thanks.
http://www.linkwitzlab.com/orion_us_specs.htm
http://www.linkwitzlab.com/orion_asp.htm
mr.sz said:
Hi Shao, in your PM to me you mentioned you say you have the complete Orion system, which I believe has an active xover which the Lightspeed Attenuator would see, I looked for the circuit of this to see what input impedance it is, but could not find the info on the web sight, do you know what it is? as this will determin the load that the Lightspeed will see.
And the cost of the Lightspeed Attenuator with post and insurance has been emailed to you.
Cheers George
I managed to get a circuit of the xover from a friend, I won't post it all just the input stage, as not to offend.
It looks as though it's input is around 10kohm which is too low for the Lightspeed or for that matter most tube preamps as well.
It would be nice if you could ask Mr. Linkwitz if it is possible to change it to more than say 60kohm, or you could use Nelson Pass's buffer stage after the Lightspeed that he posted back a couple of pages ago.
Cheers George
It looks as though it's input is around 10kohm which is too low for the Lightspeed or for that matter most tube preamps as well.
It would be nice if you could ask Mr. Linkwitz if it is possible to change it to more than say 60kohm, or you could use Nelson Pass's buffer stage after the Lightspeed that he posted back a couple of pages ago.
Cheers George
Attachments
George,
Thanks for your reply. I think the input impedance of the Orions ASP is 10.2 kohms (http://orion.quicksytes.com/viewtopic.php?f=1&t=204&p=1344#p1344). Is this what you are looking for?
Thanks.
Shao
Thanks for your reply. I think the input impedance of the Orions ASP is 10.2 kohms (http://orion.quicksytes.com/viewtopic.php?f=1&t=204&p=1344#p1344). Is this what you are looking for?
Thanks.
Shao
mr.sz said:
Yeah Shao, these are the only two options you have to make the Lightspeed or a tube preamp for that matter compatible with the xover.
1: It would be nice if you could ask Mr. Linkwitz if it is possible to change it to or more than say 60kohm.
2: Or you could use Nelson Pass's buffer stage after the Lightspeed that he posted back a couple of pages ago.
Cheers George
Yes Shao, the only one that's pre built that seems to be reasonable is this one also made here in Australia.
http://www.bursonaudio.com/Burson_Audio_Buffer.htm
If anyone has more ready made ones please post them up.
Cheers George
http://www.bursonaudio.com/Burson_Audio_Buffer.htm
If anyone has more ready made ones please post them up.
Cheers George