Hi Chris.
R4 is a 10 ohm 0805 resistor. I can send you a couple if I have some more. I'll go check in a little bit.
What is the output voltage of your CD player? The modules have a gain of 8V/V, so a 1Vrms input signal will cause the output to be clipped. That will also be very loud unless you have horribly inefficient speakers.
A 50kohm pot will be ok to use. For best performance, you can use a buffered volume control. That's basically just a pot with an opamp buffer. The CD player can easily drive the pot and the opamp can easily drive the input to the modules. You can even use the +/-12V rails for the modules to power the opamps. I use generic TL072 op amps with good success. They're very cheap too. Of course you could go with the higher end opamps too, but you'll have to pay more.
Edit: I do have a bunch of those 10 ohm 0805 resistors left. Send me an email with your address and I'll send a letter with a bunch in it.
R4 is a 10 ohm 0805 resistor. I can send you a couple if I have some more. I'll go check in a little bit.
What is the output voltage of your CD player? The modules have a gain of 8V/V, so a 1Vrms input signal will cause the output to be clipped. That will also be very loud unless you have horribly inefficient speakers.
A 50kohm pot will be ok to use. For best performance, you can use a buffered volume control. That's basically just a pot with an opamp buffer. The CD player can easily drive the pot and the opamp can easily drive the input to the modules. You can even use the +/-12V rails for the modules to power the opamps. I use generic TL072 op amps with good success. They're very cheap too. Of course you could go with the higher end opamps too, but you'll have to pay more.
Edit: I do have a bunch of those 10 ohm 0805 resistors left. Send me an email with your address and I'll send a letter with a bunch in it.
Brain,
Thanks, I'll send you a email. I don't have the money right now for either the pot or a buffer, but that just give me more time to learn and plan. I do not know the out put of my Marantz cc-48, but I would assume it is around 2v. That seems to be the going fair.
If you would point me in the direction of buffer circuits that you like it would be most apprciated.
Chris
Thanks, I'll send you a email. I don't have the money right now for either the pot or a buffer, but that just give me more time to learn and plan. I do not know the out put of my Marantz cc-48, but I would assume it is around 2v. That seems to be the going fair.
If you would point me in the direction of buffer circuits that you like it would be most apprciated.
Chris
Here's a very simple buffered potentiometer circuit that I currently use as my preamp for my D10.1s.
All you need is 4 opamps that will work at unity gain. Two dual opamp chips will work nicely. I'm currently using TL072s but have NE5532s at my disposal as well. Both are very cheap and you can power them directly from the same rails you're using for the modules. I would add a little filtering though to help clean up the rails even more - a simple RC filter would suffice.
If you're using two dual opamps then use one chip (two opamps) per channel so channel separation is maximized. The two potentiometers constitute a dual gang volume pot. You could use whatever potentiometer you'd like, but it would be wise to keep the value above 5kohm. Any opamp should be able to handle that kind of load.
How's everyone else doing with assembling/wiring/etc?
All you need is 4 opamps that will work at unity gain. Two dual opamp chips will work nicely. I'm currently using TL072s but have NE5532s at my disposal as well. Both are very cheap and you can power them directly from the same rails you're using for the modules. I would add a little filtering though to help clean up the rails even more - a simple RC filter would suffice.
If you're using two dual opamps then use one chip (two opamps) per channel so channel separation is maximized. The two potentiometers constitute a dual gang volume pot. You could use whatever potentiometer you'd like, but it would be wise to keep the value above 5kohm. Any opamp should be able to handle that kind of load.
How's everyone else doing with assembling/wiring/etc?
Attachments
Buffer circuit?
Brian,
The circuit shown will take care of the loading problem but has problems of its own. The input buffers are not really necessary and cause further complications. They would be useful if we had ready access to 1k ohm audio pots. A 10k pot should be able to be driven with minimum distortion by virtually any source in use. As always simpler is beter in the audio chain. This assumes the simpler circuit doesn’t have serious inherent limitations.
On the output side, a simple chip type buffer with unity gain should offer substantial sonici mprovement over any opamp based circuit. If the opamp is necessary for providing gain it should be followed by a buffer to disconnect reflected/induced signals from the opamps feedback circuits. I know you would think that with the very low output impedance of modern opamps this shouldn’t be a factor but it does seem to be. Also the fact an opamp is not capable of driving much of a capacitive load without ringing or instability contributes, the buffer helps here too. I also have found most buffers to have a lower sonic signature than typical opamps.
I use my own discrete buffer circuits and am not up to date on what is available currently. Anyone with more knowledge on this feel free to jump in!
Roger
Brian,
The circuit shown will take care of the loading problem but has problems of its own. The input buffers are not really necessary and cause further complications. They would be useful if we had ready access to 1k ohm audio pots. A 10k pot should be able to be driven with minimum distortion by virtually any source in use. As always simpler is beter in the audio chain. This assumes the simpler circuit doesn’t have serious inherent limitations.
On the output side, a simple chip type buffer with unity gain should offer substantial sonici mprovement over any opamp based circuit. If the opamp is necessary for providing gain it should be followed by a buffer to disconnect reflected/induced signals from the opamps feedback circuits. I know you would think that with the very low output impedance of modern opamps this shouldn’t be a factor but it does seem to be. Also the fact an opamp is not capable of driving much of a capacitive load without ringing or instability contributes, the buffer helps here too. I also have found most buffers to have a lower sonic signature than typical opamps.
I use my own discrete buffer circuits and am not up to date on what is available currently. Anyone with more knowledge on this feel free to jump in!
Roger
Hi Roger.
You're very right that the first buffers in the schematic usually aren't needed. In my setup I actually use the first opamps with a gain of 2 to drive a 20kohm pot. The output opamps are set to unity gain and do a good job of driving the inputs of the D10.1s.
The idea of using readily available opamps is merely for good performance, minimal cost, and simplicity. Anyone can wire a unity gain stable opamp as a buffer and make it work well.
You're very right that the first buffers in the schematic usually aren't needed. In my setup I actually use the first opamps with a gain of 2 to drive a 20kohm pot. The output opamps are set to unity gain and do a good job of driving the inputs of the D10.1s.
The idea of using readily available opamps is merely for good performance, minimal cost, and simplicity. Anyone can wire a unity gain stable opamp as a buffer and make it work well.
OOPS - inserted tube buffer 'tween DAC & ColdAmp without powering down. Consequence is one Lowther silver voice coil is an ex-voice coil.
So can't really progress build until the drive unit visits hospital - my fallback Quad speakers are a tad insensitive.
Wouldn't have happened if I wasn't paddling in the pool of 'never mind the quality, feel the width' amplification.
Mind you, next time I'll power off first....
And this effing forum still logs me out before I can complete an 8 line response.
So can't really progress build until the drive unit visits hospital - my fallback Quad speakers are a tad insensitive.
Wouldn't have happened if I wasn't paddling in the pool of 'never mind the quality, feel the width' amplification.
Mind you, next time I'll power off first....
And this effing forum still logs me out before I can complete an 8 line response.
Thank you,
Brain
I completed my amps on Monday, thanks to Brains donation of more 10 ohm resistors. (Hands aren't as nimble as they used to be.)
With 20hrs. on them they might just replace my el84 PP. Smooth and detailed, and have great synergy with my B200 drivers.
I will write a more detailed description of my jurney early next week.
Dam good kit,
Chris
Brain
I completed my amps on Monday, thanks to Brains donation of more 10 ohm resistors. (Hands aren't as nimble as they used to be.)
With 20hrs. on them they might just replace my el84 PP. Smooth and detailed, and have great synergy with my B200 drivers.
I will write a more detailed description of my jurney early next week.
Dam good kit,
Chris
D10.1 Kits
Hi Brian,
Do you still offer D10.1 kits?
How is your opinion growing on the coilcraft 1360 chokes?
You sell them seperatly?
As I am considering to use the amp in conjunction with an AMP11 in an active speaker, the last question is does your board allow a sngle 24 volt supply without too many changes?
Kind regads, Rick
Hi Brian,
Do you still offer D10.1 kits?
How is your opinion growing on the coilcraft 1360 chokes?
You sell them seperatly?
As I am considering to use the amp in conjunction with an AMP11 in an active speaker, the last question is does your board allow a sngle 24 volt supply without too many changes?
Kind regads, Rick
Hi Rick.
I don't have any more kits at the moment. I'm still waiting for everyone's opinion of the current kit. It may be a little while before that happens because some people are having unforseen non-technical issues, lack of time, etc.
I really like the coilcraft 1360 inductors. They work well in this application. Sorry, I don't sell them separately. I get them directly from the manufacturer.
The current board is not intended to be used with a single 24 supply (without a number of changes and board hacks). It is only meant to be used with a +/-12V supply so that it doesn't need to use input and output coupling caps that color the sound. The result is just that, very neutral and uncolored sound
as well as fantastic imaging because of the dual mono configuration. I could make changes to the schematic and board to allow operation from a single 24V supply but it will then require input and output coupling caps which I'd prefer not to use.
I don't have any more kits at the moment. I'm still waiting for everyone's opinion of the current kit. It may be a little while before that happens because some people are having unforseen non-technical issues, lack of time, etc.
I really like the coilcraft 1360 inductors. They work well in this application. Sorry, I don't sell them separately. I get them directly from the manufacturer.
The current board is not intended to be used with a single 24 supply (without a number of changes and board hacks). It is only meant to be used with a +/-12V supply so that it doesn't need to use input and output coupling caps that color the sound. The result is just that, very neutral and uncolored sound
as well as fantastic imaging because of the dual mono configuration. I could make changes to the schematic and board to allow operation from a single 24V supply but it will then require input and output coupling caps which I'd prefer not to use.
I can't recommend using them with the Charlize simply because the 1360s are surface mount parts, but no one will stop you if you do decide to give it a try.Rick NL said:
panomaniac said:Here is one of the "lack of time" guys.
But not to worry! I got a +/-12V supply running this afternoon and wired up the modules. Just want to double check everything before the 1st power up.
Should have some news for you soon, Brian. looking forward to hearing it.
Thanx again.
No problem. Take your time, there's no rush. I'll be busy with the TAS5261 project for a little while anyway
O.K. Here is the new toy, up an running since last monday night.
1st Build
I have to say now that I'm dispointed with myself that I had Brain solder the MP7720 chip in. I tried to build the Amp 3 and had lifted the traces on the Tripath chip. I have no dout that, that would not have happened with soldering in the MP7720. Much more space between leads.
Brian's boards had more space for me to work. When compaired to the AMP 3. The boards was easy to populate. I used a 40w, temp controlled iron with a .3mm head. I tried some solder paste, but had difficulty with overflow. I used sone wire solder my father-in -law gave me. I don't know what it is, but it was tiny diameter and work like a charm.
I did make a mistake with the electrolitic caps. I had reversed one rail, because (-) should go to ground.
Luckly, I realized before turning it on that I was work with a dual rail supply rather than single, and turned caps back to how the schematic had shown.
2nd Supply
Two 30VA, Avel, dual 15v toroids thrugh some Rat Shack 4A recifiers. To the 12000uf caps, then LD1085V12. (The LD1085V12 is fixed at 12v so no messing with setting voltage.) To 1000uf cap, and on to the amps.
3rd Experience
First this that Struck me was no turn on pop. At first the top end was a little strident, but that when completely away with in the first ten hours. After that the sound natural and balanced, and has more command of the drivers them my EL84 PP UL amp. I have about 50 hrs on the amps now, and I like to wait at least 100hrs before giving to many more empressions.
4th To do
I have connented the amps right to the cd player. It has a volume control, but I can't get it past the second tick out of twelve witout being blasted out of the room. So, the nice little buffer with volume control Brain suggested is going to be built ASAP.
O' I can hear the Cd player changeing discs and songs. Will this be filtered out with the use of a buffer? Also, I'm considering buying the Monica2 dac. I have heard the tripath chips have problem with it, but will Brians amps with his buffer?
5th
I like this kit. It was a good experince for a novice. I do not feel the need to have any changes with the build or quality of the components.
Chris
1st Build
I have to say now that I'm dispointed with myself that I had Brain solder the MP7720 chip in. I tried to build the Amp 3 and had lifted the traces on the Tripath chip. I have no dout that, that would not have happened with soldering in the MP7720. Much more space between leads.
Brian's boards had more space for me to work. When compaired to the AMP 3. The boards was easy to populate. I used a 40w, temp controlled iron with a .3mm head. I tried some solder paste, but had difficulty with overflow. I used sone wire solder my father-in -law gave me. I don't know what it is, but it was tiny diameter and work like a charm.
I did make a mistake with the electrolitic caps. I had reversed one rail, because (-) should go to ground.
Luckly, I realized before turning it on that I was work with a dual rail supply rather than single, and turned caps back to how the schematic had shown. 2nd Supply
Two 30VA, Avel, dual 15v toroids thrugh some Rat Shack 4A recifiers. To the 12000uf caps, then LD1085V12. (The LD1085V12 is fixed at 12v so no messing with setting voltage.) To 1000uf cap, and on to the amps.
3rd Experience
First this that Struck me was no turn on pop. At first the top end was a little strident, but that when completely away with in the first ten hours. After that the sound natural and balanced, and has more command of the drivers them my EL84 PP UL amp. I have about 50 hrs on the amps now, and I like to wait at least 100hrs before giving to many more empressions.
4th To do
I have connented the amps right to the cd player. It has a volume control, but I can't get it past the second tick out of twelve witout being blasted out of the room. So, the nice little buffer with volume control Brain suggested is going to be built ASAP.
O' I can hear the Cd player changeing discs and songs. Will this be filtered out with the use of a buffer? Also, I'm considering buying the Monica2 dac. I have heard the tripath chips have problem with it, but will Brians amps with his buffer?
5th
I like this kit. It was a good experince for a novice. I do not feel the need to have any changes with the build or quality of the components.
Chris
Attachments
Hi Chris. Thank you for posting your building/listening experience here. It's great to hear that someone finally has a kit up and running. Nice job on the supply 
There's no turn on pop because there aren't any input coupling caps that need to be charged up. All you should hear is a tiny little click when you turn the power supply on and the chip is enabled. Class d amps, even the low power ones, really do seem to have "more command of the drivers".
The modules have a gain of 8V/V, so the signal output from your CD player is pretty strong. The buffered volume control schematic I posted earlier will work fine, or you can do away with the op amps before the volume pot and only use one op amp if you'd like to make things even simpler.
The noises you're hearing are coming from the CD player itself because the input level is so high. The noises will be reduced when you add a potentiometer between the CD player and the amp. I don't know the capabilities of the Monica2 DAC but I'd be willing to bet it would work fine with these modules as long as it has minimal DC offset. Don't forget these modules are DC coupled, so any DC present on the input will show up 8 times larger at the output.
Corloc said:
There's no turn on pop because there aren't any input coupling caps that need to be charged up. All you should hear is a tiny little click when you turn the power supply on and the chip is enabled. Class d amps, even the low power ones, really do seem to have "more command of the drivers".
Corloc said:
The modules have a gain of 8V/V, so the signal output from your CD player is pretty strong. The buffered volume control schematic I posted earlier will work fine, or you can do away with the op amps before the volume pot and only use one op amp if you'd like to make things even simpler.
Corloc said:
The noises you're hearing are coming from the CD player itself because the input level is so high. The noises will be reduced when you add a potentiometer between the CD player and the amp. I don't know the capabilities of the Monica2 DAC but I'd be willing to bet it would work fine with these modules as long as it has minimal DC offset. Don't forget these modules are DC coupled, so any DC present on the input will show up 8 times larger at the output.
Well I've been listening to these for awhile now, and they sound very good indeed. Much like the Tripath stuff, to my ear. Maybe a little smoother, easier, but certainly not lacking in detail.
Very good soundstage. They sound large and open, plenty of space. (I like that). No troubles in the bass, but there shouldn’t be - because of no input cap and 2 power supplies 2x 10000uF before the board. Should be rock steady.
The chips are tiny, much smaller than the Tripath chips, and they run cooler.
Very nice class D amp. Got lots of good stuff going on. Also very clean on the RF end. Brian puts together a nice board.
I'm going to do more critical listening in the coming week, then the little guys have to go back to chilly Pennsylvania. Brrrrr......
Good work, Brian!
Very good soundstage. They sound large and open, plenty of space. (I like that). No troubles in the bass, but there shouldn’t be - because of no input cap and 2 power supplies 2x 10000uF before the board. Should be rock steady.
The chips are tiny, much smaller than the Tripath chips, and they run cooler.
Very nice class D amp. Got lots of good stuff going on. Also very clean on the RF end. Brian puts together a nice board.
I'm going to do more critical listening in the coming week, then the little guys have to go back to chilly Pennsylvania. Brrrrr......
Good work, Brian!
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