Counterpoint
Look what I got working last night!
I'll post more on sonics & observations later, but suffice to say it does sound very good! I need to listen more broadly before giving more opinion.....
Fran
Look what I got working last night!
I'll post more on sonics & observations later, but suffice to say it does sound very good! I need to listen more broadly before giving more opinion.....
An externally hosted image should be here but it was not working when we last tested it.
Fran
So now my interest is seriously piqued. Is this one channel or have been both been combined onto one board? I couldn't quite make this out from the picture on my phone. And are they large white caps?
Keep up the good work Fran and let us know how the listening goes!
Russ
Keep up the good work Fran and let us know how the listening goes!
Russ
No, theres 2 boards, each the same footprint as an IVY. The big white caps are the output caps, I parallelled 2 x 0.68uF. My pre has an input impedance of 27k and I see no DC at the RCAs. Floats a little when not connected to the pre, but once connected theres nothing.
Sonics are good. but I need to test more widely first.
Fran
Sonics are good. but I need to test more widely first.
Fran
Re: Friday has arrived!
Just out of curiosity: why FIR? why not IIR bi-quads? Doing a good FIR is MUCH harder than a bi-quad in terms of chip resources.
I realize that you, Russ, probably don't know the answer, but maybe someone can point out what one gets with FIR that you can't have with a chain of bi-quads and much lower resource cost. There is something here I don't get.
peter
How many taps for the filter?Russ White said:
Just out of curiosity: why FIR? why not IIR bi-quads? Doing a good FIR is MUCH harder than a bi-quad in terms of chip resources.
I realize that you, Russ, probably don't know the answer, but maybe someone can point out what one gets with FIR that you can't have with a chain of bi-quads and much lower resource cost. There is something here I don't get.
peter
Re: Re: Friday has arrived!
Because it is mainly intended to customize the response of the existing FIR low pass filter.
schro20 said:
Because it is mainly intended to customize the response of the existing FIR low pass filter.
Re: Counterpoint
Is this a discrete IVY? On the TP website it is still mentioned as "coming soon".
Scanspeakman
woodturner-fran said:
Is this a discrete IVY? On the TP website it is still mentioned as "coming soon".
Scanspeakman
Re: Re: Counterpoint
It is an early prototype.
The final version is very similar but with some improvements.
It should be noted, there are opamps involved, but they simply set and maintain bias voltages (input and output). The signal is handled by the discrete components.
Cheers!
Russ
scanspeakman said:
It is an early prototype.
The final version is very similar but with some improvements.
It should be noted, there are opamps involved, but they simply set and maintain bias voltages (input and output). The signal is handled by the discrete components.
Cheers!
Russ
Lukas Fikus
rooting around the net I ran across Lampizator. Lukas Fikus says some great things about the Buffalo DAC and has some interesting ideas about DAC output and Transport output
English is obviously not his primary language and his drawings are hard to understand but I learned a lot from his site and he got me to dust off my oscope
http://www.lampizator.eu/LAMPIZATOR/REFERENCES/Buffalo DAC/BuffaloDAC.html
rooting around the net I ran across Lampizator. Lukas Fikus says some great things about the Buffalo DAC and has some interesting ideas about DAC output and Transport output
English is obviously not his primary language and his drawings are hard to understand but I learned a lot from his site and he got me to dust off my oscope
http://www.lampizator.eu/LAMPIZATOR/REFERENCES/Buffalo DAC/BuffaloDAC.html
Re: Re: Re: Counterpoint
It looks really interesting Russ. Any idea when this i/v will be availlable?
Scanspeakman
Russ White said:
It looks really interesting Russ. Any idea when this i/v will be availlable?
Scanspeakman
I've been listening to this a fair bit over the last few days, well really since I posted here last. I wanted to be sure of what I was hearing, and I suppose to let the counterpoint have a bit of a test and see that it was stable etc over a short time at least.
I was/am a little concerned about the heat on the BC550/560 used in the design (50-60 degC) but the interior case temp (in a fairly crowded case) along with a good bit of heat thrown out by the LCBPS is only 35 degC. So my answer to that is I dunno.
To the technical things first. The build was straightforward enough - even though these are very much evaulation boards Russ was very helpful with clear instructions on what to do. Everything went in AOK and I had the 2 boards populated in no time. Components all came from mouser with the exception of some output caps which I had myself. For those who are thinking of this when Russ/Brian release it, the build is no more difficult than any of the other kits. Note that each board is for one channel, so if you are thinking of going that route, leave room in your case for 2 boards. With the heat it might not be a great idea to stack the boards either.
The counterpoint, like the IVY is all set for balanced operation, and I am only set up for SE throughout my system. So I would be using just one of the outputs. Russ had warned back in the thread that there was a fairly severe turn on and turn off thump when using in SE mode... but that this was not the same for balanced use as the thump was common mode. So with everything else powered off I hooked it up and turned everything else on. I was expecting some kind of noise etc, but it was absolutely dead quiet. I think Russ had said he had a bit of hiss somewhere at some stage, but I didn't hear any of that. Now my system wouldn't be the most sensitive (quad ESLs and a 10WPC minialeph, low gain aikido pre) and I have yet to try it with my full range fonken speakers. But anyway, no hiss hum etc at all.
I actually accidentally turned off the DAC that night before turning off the pre and power but to my surprise there was only the softest of thumps. Waited a while and turned it back on - same thing. So in my system at least, the thump is minimal and I wouldn't be concerned about it at all. There is an output cap to block DC offset, but this isn't that high before the cap I think I had 10-20mV on one board and a bit higher on the other, maybe 50mV.
So what about sonics? Well this is another reason why I've delayed for a few days writing this. I don't know how exactly to describe what I'm hearing. First of all, let me skip ahead by saying it is very good. Fullsome and fast bass, not shy of treble but with no sibilance or harshness. - if thats on the recording, you'll get it, if its not you won't. Very musical, not a trace of digital harshness, very dynamic, crisp without being clipped. In short, bloody good.
But the IVY had all this too, so is it better than the IVY? Well in my system, to my ears, yes it is. And the reason for this is the soundstage. This is the bit that I have found hard to describe. Performers seem to pop into 3 dimensions in an kind of uncanny way. One of the tracks (indeed albums) I've been listening too is a tribute to a banjo player Derroll Adams (see here). Very well recorded album, but theres a track that starts with water lapping and I tell you you will rise your feet off the floor onto the sofa to stop them getting wet. Its kinda freaky to be honest - like the way those binaural recordings are when played back on headphones. Singers seem to step forward and there seems to be more depth to them - you perceive them as being more real in space. Kinda like you could look at the moon and see it as a flat disc, but on another night you could see it as a sphere. Stupid analogy I know, but hopefully you get what I mean. Busier music has oodles of separation and of course it never runs out of steam or sounds congested/glassy when things get complicated. Its absolutely glorious on some of the verve/impulse recordings - John Lee on it serves me right to suffer (impulse) is outstanding.
Anyway, this post is way longer than I intended. Russ/Brian, I am sorry for that, and the fact that it will probably put the counterpoint even more in demand. A friend who I've just built a buffalo for has already been begging me to get him the counterpoint when they are available. BTW, thats a positive, because he had my buffalo for quite a while in his system and has heard it all the way along, from stock, to teddyregs, to adding those caps to the IVY, to the Vreg mod and now the counterpoint. He is not involved in DIY at all so is a kind of neutral observer, and one I trust. He even would agree with what I've said above - so its not a case of me being the proud pappa. (thats Russ/Brians position!).
So what else is there? Just thanks to Russ and Brian for the chance to try this out and for producing it in the first place. 🙂
Fran
I was/am a little concerned about the heat on the BC550/560 used in the design (50-60 degC) but the interior case temp (in a fairly crowded case) along with a good bit of heat thrown out by the LCBPS is only 35 degC. So my answer to that is I dunno.
To the technical things first. The build was straightforward enough - even though these are very much evaulation boards Russ was very helpful with clear instructions on what to do. Everything went in AOK and I had the 2 boards populated in no time. Components all came from mouser with the exception of some output caps which I had myself. For those who are thinking of this when Russ/Brian release it, the build is no more difficult than any of the other kits. Note that each board is for one channel, so if you are thinking of going that route, leave room in your case for 2 boards. With the heat it might not be a great idea to stack the boards either.
The counterpoint, like the IVY is all set for balanced operation, and I am only set up for SE throughout my system. So I would be using just one of the outputs. Russ had warned back in the thread that there was a fairly severe turn on and turn off thump when using in SE mode... but that this was not the same for balanced use as the thump was common mode. So with everything else powered off I hooked it up and turned everything else on. I was expecting some kind of noise etc, but it was absolutely dead quiet. I think Russ had said he had a bit of hiss somewhere at some stage, but I didn't hear any of that. Now my system wouldn't be the most sensitive (quad ESLs and a 10WPC minialeph, low gain aikido pre) and I have yet to try it with my full range fonken speakers. But anyway, no hiss hum etc at all.
I actually accidentally turned off the DAC that night before turning off the pre and power but to my surprise there was only the softest of thumps. Waited a while and turned it back on - same thing. So in my system at least, the thump is minimal and I wouldn't be concerned about it at all. There is an output cap to block DC offset, but this isn't that high before the cap I think I had 10-20mV on one board and a bit higher on the other, maybe 50mV.
So what about sonics? Well this is another reason why I've delayed for a few days writing this. I don't know how exactly to describe what I'm hearing. First of all, let me skip ahead by saying it is very good. Fullsome and fast bass, not shy of treble but with no sibilance or harshness. - if thats on the recording, you'll get it, if its not you won't. Very musical, not a trace of digital harshness, very dynamic, crisp without being clipped. In short, bloody good.
But the IVY had all this too, so is it better than the IVY? Well in my system, to my ears, yes it is. And the reason for this is the soundstage. This is the bit that I have found hard to describe. Performers seem to pop into 3 dimensions in an kind of uncanny way. One of the tracks (indeed albums) I've been listening too is a tribute to a banjo player Derroll Adams (see here). Very well recorded album, but theres a track that starts with water lapping and I tell you you will rise your feet off the floor onto the sofa to stop them getting wet. Its kinda freaky to be honest - like the way those binaural recordings are when played back on headphones. Singers seem to step forward and there seems to be more depth to them - you perceive them as being more real in space. Kinda like you could look at the moon and see it as a flat disc, but on another night you could see it as a sphere. Stupid analogy I know, but hopefully you get what I mean. Busier music has oodles of separation and of course it never runs out of steam or sounds congested/glassy when things get complicated. Its absolutely glorious on some of the verve/impulse recordings - John Lee on it serves me right to suffer (impulse) is outstanding.
Anyway, this post is way longer than I intended. Russ/Brian, I am sorry for that, and the fact that it will probably put the counterpoint even more in demand. A friend who I've just built a buffalo for has already been begging me to get him the counterpoint when they are available. BTW, thats a positive, because he had my buffalo for quite a while in his system and has heard it all the way along, from stock, to teddyregs, to adding those caps to the IVY, to the Vreg mod and now the counterpoint. He is not involved in DIY at all so is a kind of neutral observer, and one I trust. He even would agree with what I've said above - so its not a case of me being the proud pappa. (thats Russ/Brians position!).
So what else is there? Just thanks to Russ and Brian for the chance to try this out and for producing it in the first place. 🙂
Fran
woodturner-fran said:
Hi Fran,
No apology required for the long post. 🙂 I am very pleased you like the beta counterpoint.
The hiss I heard could well have been from my test rig setup which was not optimal. You probably have yours in a better situation.
I have to agree that the sound is something special. I have never done a no-global feedback design like that before, so I was pleasantly surprised by the result.
Don't worry much about the hot transistors they should stabilize at the numbers you quoted as long as you keep the same supply voltage.
The counterpoint is a constant current on the power supply regardless of signal. Much like the IVY in that regard.
The final counterpoint is the same circuit core surrounded with a couple new helpers. First there is a integrator to get offset to zero with no output caps. Second there is an output relay and a delay cct on board to prevent any turn-on/off nastiness. I also figured out a very nifty way to drive the input bias which resulted in even lower input impedance (around 10 milliohm).
This new version can be used with *either* symmetrical current feedback, or with no global feedback. The current feedback unusual in that it does not have any need for compensation because its always working from a high impedance. Thus none of the slewing issues opamps can run into.
It is not super symmetrical, but it is very much symmetrical. 🙂 It can even take a single ended current input and convert it to balanced. 🙂
I should know soon if it works as planned.
Thanks again for the report and for taking the time to build my humble circuit.
Cheers!
Russ
Just to show my reason for excitement concerning the new counterpoint. Here is a simulation FFT shot of the counterpoint at 1Khz (20khz is nearly identical distortion wise).
This is a single ended output at 1VRMS.
Balanced output drops 2nd order distortion to nothing.
Now get this. I simulated that result with mismatched Qs (beta 20%) and 4 ma more current through one half the the cct (simulating mismatched Rs etc). The integrator works very very well. 🙂
Cheers!
Russ
This is a single ended output at 1VRMS.
Balanced output drops 2nd order distortion to nothing.
Now get this. I simulated that result with mismatched Qs (beta 20%) and 4 ma more current through one half the the cct (simulating mismatched Rs etc). The integrator works very very well. 🙂
Cheers!
Russ
Attachments
Fran, thank you for elucidating on the Caps and, as ever, for an excellent summary. Thank you Russ for keeping us up-to-date with the production boards.
Russ, I was just wondering if this new I/V stage will be compatible with any new Sabre32 boards on the drawing boards?
Russ
Russ, I was just wondering if this new I/V stage will be compatible with any new Sabre32 boards on the drawing boards?
Russ
rjbaldwin,
short version: go get counterpoint when its available!
Russ/Brian:
Somewhere, maybe in the IVY manual, I seem to recallseeing the IVY used in SE mode. Can that be done? ie use the IVY as an output buffer for a regular SE output source? If so whats the best way to connect the source?
Fran
short version: go get counterpoint when its available!
Russ/Brian:
Somewhere, maybe in the IVY manual, I seem to recallseeing the IVY used in SE mode. Can that be done? ie use the IVY as an output buffer for a regular SE output source? If so whats the best way to connect the source?
Fran
Very nice eh fran😉
I've been up to neck at work so not had as much time as I wanted to play about with the Counterpoint
I did manage to quickly build it up and do some sound evaluations, I'd say my thoughts are very similar to yours, I find it very analogue sounding, reminds me of good NOS but with more dynamics.
The soundstage is very wide and theres lots of depth
My transistors also get pretty warm but I don't think its enough to cause problems tbh
Mine did have some background hum to start with but after tweaking about with the supply (thanks for the tip Russ) its virtually gone
Big thanks to Russ and Brian for the prototype boards, the updated Counterpoint should be a great match with the Buffalo😉
I've been up to neck at work so not had as much time as I wanted to play about with the Counterpoint
I did manage to quickly build it up and do some sound evaluations, I'd say my thoughts are very similar to yours, I find it very analogue sounding, reminds me of good NOS but with more dynamics.
The soundstage is very wide and theres lots of depth
My transistors also get pretty warm but I don't think its enough to cause problems tbh
Mine did have some background hum to start with but after tweaking about with the supply (thanks for the tip Russ) its virtually gone
Big thanks to Russ and Brian for the prototype boards, the updated Counterpoint should be a great match with the Buffalo😉
What input voltage did/do you runs yours at t.?
Would be interested to see if you get the same temps as me although the temp is totally stable (and was from first power on). Just would be interesting to see.
Fran
Would be interested to see if you get the same temps as me although the temp is totally stable (and was from first power on). Just would be interesting to see.
Fran
Hi,
I am new at this forum.
I use a 1.2 buffalo dac with LCaudio ZAPfilter I/V stage, very nice.
the Buffalo is powered by 4x6V/3A batteries.
From message #1035 i have been reading about the vref mod.
I would like to do that mod to, but have seen different solutions. confused
Can someone write a little howto guide to do the Vref mods on a hardwired and most easy/effective way (no print)
Thx!
I am new at this forum.
I use a 1.2 buffalo dac with LCaudio ZAPfilter I/V stage, very nice.
the Buffalo is powered by 4x6V/3A batteries.
From message #1035 i have been reading about the vref mod.
I would like to do that mod to, but have seen different solutions. confused
Can someone write a little howto guide to do the Vref mods on a hardwired and most easy/effective way (no print)
Thx!
Just one design, but improved current source. Post 1085 should be he latest circuit. The rest of the discussion are on the selection of components, and adjustment for output voltage
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