...Sonance 260 modifications?
Uriah,
How did you modify the Sonance 260 to use with this board? What parts did you keep? I got a couple of them from ebay and they are pretty nice on their own. I don't know how they sound but they are in great shape. The trafos are really heavy! I wasn't expecting that!
Uriah,
How did you modify the Sonance 260 to use with this board? What parts did you keep? I got a couple of them from ebay and they are pretty nice on their own. I don't know how they sound but they are in great shape. The trafos are really heavy! I wasn't expecting that!
LDR Lightspeed kit
What is supposed to be in the lightspeed package?
How many resistors and what value?
What is supposed to be in the lightspeed package?
How many resistors and what value?
CCS output impedance
Hi,
before I receive my kits I have been looking at the current sink resistor ratio issue.
It seems from the papers on the Howland CS, that the impedance can be low or high or very high.
It also seems the impedance can be negative or positive from each of the above conditions.
Where the impedance ends up depends critically on the 47k:22k resistor ratio.
Poor matching gives low impedance, either +ve or -ve. With Uriah's good work in getting resistor matches, we can discount this outcome.
Good matching will give high impedance, but still the risk of either -ve or +ve value. This likely where we are with the supplied resistors.
Very good matching will give very high impedance and the measurement technique I am looking at will determine how to place the components to achieve the +ve impedance that is necessary.
Can some confirm that the -ve impedance is not good for the CCS???? If it is unimportant then I can stop now.
Next.
Can anyone confirm that the performance of the amplifier might improve if the impedance is very high and +ve rather than the other options?
The results of this measuring and interpretation of the data, if necessary, will go in the build thread.
Hi,
before I receive my kits I have been looking at the current sink resistor ratio issue.
It seems from the papers on the Howland CS, that the impedance can be low or high or very high.
It also seems the impedance can be negative or positive from each of the above conditions.
Where the impedance ends up depends critically on the 47k:22k resistor ratio.
Poor matching gives low impedance, either +ve or -ve. With Uriah's good work in getting resistor matches, we can discount this outcome.
Good matching will give high impedance, but still the risk of either -ve or +ve value. This likely where we are with the supplied resistors.
Very good matching will give very high impedance and the measurement technique I am looking at will determine how to place the components to achieve the +ve impedance that is necessary.
Can some confirm that the -ve impedance is not good for the CCS???? If it is unimportant then I can stop now.
Next.
Can anyone confirm that the performance of the amplifier might improve if the impedance is very high and +ve rather than the other options?
The results of this measuring and interpretation of the data, if necessary, will go in the build thread.
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I also recieved my package, nicely done! I can't wait to heat up my iron.
Also, if someone has some inexpensive case suggestions I would appreciate any tips. I'm thinking right now I'll just get an alluminum Hammond chassis from Mouser to hold everything together.
Remember to order separately the top cover. Read carefully the documentation regarding this aspect. I made the mistake of not buying it and I had now an open air amplifier, waiting to go to buy some kind of cover.
Other than that, they are not quite hard, but hard and stable enought for most purposes. Easy to work with.
Regards,
Regi
Yep, I'm looking for case options as well for a two channel box with two of uriah's transformer toroids.
Treytexag
PPC
Go here Google Docs
The bottom board is the board that holds the LDRs that you have.
So there are two positive power inputs and one negative. You will give them power from the 100k dual log pot as shown in George' circuit. Populate the board as my diagram shows. Which positive wire goes to which positive input? If its loud at min volume then switch the positive wires to the other positive inputs and that will be corrected.
Uriah
Let's look at my attached schematic. It is made from the boards that Uriah is supplying with the kit. Uriah please, point out any mistake you can notice, as I couldn't found these schematics so I made them myself.
Is attached too that black-background layout taken from your website, from which I was able to make the other attached schematic.
As we have just been told, we hook up the positive sides as shown in my schematic. If it is full loud at min volume, then switch the positive wires to the other positive inputs. That's clear alright. Next step:
What about the negative pads for those who are making our own PSU? Should we connect each one by each own wire to a common point in the PSU ground? I am assuming that we are using my PSU (only one rail for both channels, shared PSU). You are using 2 PSUs, one for each channel.
Regards,
Regi
Is attached too that black-background layout taken from your website, from which I was able to make the other attached schematic.
As we have just been told, we hook up the positive sides as shown in my schematic. If it is full loud at min volume, then switch the positive wires to the other positive inputs. That's clear alright. Next step:
What about the negative pads for those who are making our own PSU? Should we connect each one by each own wire to a common point in the PSU ground? I am assuming that we are using my PSU (only one rail for both channels, shared PSU). You are using 2 PSUs, one for each channel.
Regards,
Regi
Attachments
LDR Board
I have that Doc.
It makes no sense to me, the LDR board has holes with no identification.
I have built a chipamp from BrianGT, the MyRefC from Uriah, and a B1 from pass and never before had a board with no identification.
What I need to finish this LDR board is four replacement LDR's damaged due to no documentation or informed where to get the information.
and a drawing showing where each wire from the dual pot goes on the board
and/or a picture of a wired unit with the wires in the picture to show the connections.
I have that Doc.
It makes no sense to me, the LDR board has holes with no identification.
I have built a chipamp from BrianGT, the MyRefC from Uriah, and a B1 from pass and never before had a board with no identification.
What I need to finish this LDR board is four replacement LDR's damaged due to no documentation or informed where to get the information.
and a drawing showing where each wire from the dual pot goes on the board
and/or a picture of a wired unit with the wires in the picture to show the connections.
REgi your schematic is correct. Negative can just be jumpered together and then your 0V from your supply goes there. Or you can take two wires from your 0V. Doesnt matter. Yes I use 2 supplies in my Lighter Note so thats why this board has room for two 0V.
I am working with ppc blaster on the phone so he will be up and running with the LDR board.
Uriah
If any of you DONT understand how to use the LDRs in the pseudo Lightspeed board or where to place the components then dont go ahead and wire it up til you do. If you need to talk to me on the phone thats fine to. Just email me and I will email you my number.
LDR 1 and LDR2 are a pair.
LDR 3 and LDR4 are a pair.
On the board from left to right are LDR1, LDR3, LDR2, LDR4 so the first and third are a pair and the second and fourth are a pair. When you look at it with this text in front of you it should make more sense. See, LDRs 1 and 2 are the Series LDRs and 3 and 4 are the shunt LDRs.
There are 4 resistors that come with the packet. 2 are 1k and 2 are 68R.
The resistors are labeled from left to right as R1, R2, R3, R4 and are right near the LDR they protect. The Series LDRs need 1k and the Shunt need 68R.
R1 and LDR1
R2 and LDR3
R3 and LDR2
R4 and LDR4
P2 is a 200R trimmer. It should be turned midway approximately before firing up your circuit. It will trim the shunt LDRs to perfect match at lowest resistance. Set it and forget it once you measure the shunt LDRs at min resistance. It takes a lot of current to make the LDRs run at min resistance so when I measure 400 of them at a time there is no power supply that I know of that will allow me extreme control over voltage stability while putting out the amps I need to get all 400+ to go to 50R. So I measure down to about 250R for my min measurement. This 200R will adjust that min resistance.
P1 is a 5k single gang pot and will adjust balance of the stereo amp from left to right and right to left. Yes the matching is really good but your room and rest of your components may need to have this balance pot in place to adjust the stereo image. Set this at your normal listening position. Tune this by ear because its not the resistance that matters here. We may intentionally mismatch the resistance to get stereo image perfectly centered due to room inconsistencies or for instance one of my speakers is a tad more efficient than the other. Why? I dunno. But it is.
Uriah
LDR 1 and LDR2 are a pair.
LDR 3 and LDR4 are a pair.
On the board from left to right are LDR1, LDR3, LDR2, LDR4 so the first and third are a pair and the second and fourth are a pair. When you look at it with this text in front of you it should make more sense. See, LDRs 1 and 2 are the Series LDRs and 3 and 4 are the shunt LDRs.
There are 4 resistors that come with the packet. 2 are 1k and 2 are 68R.
The resistors are labeled from left to right as R1, R2, R3, R4 and are right near the LDR they protect. The Series LDRs need 1k and the Shunt need 68R.
R1 and LDR1
R2 and LDR3
R3 and LDR2
R4 and LDR4
P2 is a 200R trimmer. It should be turned midway approximately before firing up your circuit. It will trim the shunt LDRs to perfect match at lowest resistance. Set it and forget it once you measure the shunt LDRs at min resistance. It takes a lot of current to make the LDRs run at min resistance so when I measure 400 of them at a time there is no power supply that I know of that will allow me extreme control over voltage stability while putting out the amps I need to get all 400+ to go to 50R. So I measure down to about 250R for my min measurement. This 200R will adjust that min resistance.
P1 is a 5k single gang pot and will adjust balance of the stereo amp from left to right and right to left. Yes the matching is really good but your room and rest of your components may need to have this balance pot in place to adjust the stereo image. Set this at your normal listening position. Tune this by ear because its not the resistance that matters here. We may intentionally mismatch the resistance to get stereo image perfectly centered due to room inconsistencies or for instance one of my speakers is a tad more efficient than the other. Why? I dunno. But it is.
Uriah
because we listen to the attenuated output.
The attenuation is a ratio to the input signal. -6dB is an attenuation ratio of 2:1
If the two attenuation ratios across the two channels match and the gains in the rest of the system also match then you hear stereo. Whether a twin track pot has one at 101k and the other at 99k does not matter. 2% variation in the load should not affect a good source.
A good pot maintains matching of it's attenuation ratio.
Adjust the LDR trim so that the ratio matches. If the same (mono) test signal is sent to both LDRs and you read the same output voltage then you have matched the ratios. But this will be undone if the remainder of the system has unmatched gains between the channels.
If you were to meause the output comparison at the listening position then that corrects for all the gain errors throughout the system.
next best is comparing output voltage at the speaker terminals with a mono test signal applied to the sources inputs. A test CD or a test record to the RIAA pre, etc.
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Thanks Andrew. Yeah it seems, and has been like this for about 2 years on different amps and preamps, that one of my speakers is more efficient than the other. Have switched them to other sides of the amp and it remains that the same one is louder than the other. Wonder if I damaged it early in my DIYing. Anyway, the balance helps me with this.
Uriah
Uriah
The postman called today with my Ref c and Ldr 🙂 Thank you for all your hard work not easy with moving house etc regards john
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