so, if the guys would be selling the gerbers through swap meet or vendors, at a symbolic price, that would be ok with you ?
and its not a joke
just an attempt to do something about this
but honestly
I think you will have to actually sell boards, to get much further with this
and its not a joke
just an attempt to do something about this
but honestly
I think you will have to actually sell boards, to get much further with this
Thanks for the compliment Tinitus. I have become a little inactive in my own right and I have since joined forces with ZUS after Randy's passing and we are trying to re-vitalize the brand. So Radical Audio Synthesis has taken a bit of a back-seat.
pardon me Nico, but isn't that what you are doing yourself, commercially, on your homesite ?
Of course it would be fine to sell boards and the like and their marketing effort will be rewarded in that sense like all kit creators. On DIY I believe it to be a forum that shares both knowledge and experience, some times negative but mostly positive.
Just look how a guy like Anthony (Begun) has grown in both abilities and understanding to name but one of the members that I don't know from a bar of soap, but I take a genuine interest in him.
Kindest Regard
Nico
Kurt, I am sorry to have a dig at you, it was just a strange way to push an idea. I have also done that once some six years ago and got shot down by some of the old hands here. Which made me appreciate that everybody here is not trying to be smart but rather helpful.
Just look how a guy like Anthony (Begun) has grown in both abilities and understanding to name but one of the members that I don't know from a bar of soap, but I take a genuine interest in him.
Kindest Regard
Nico
Kurt, I am sorry to have a dig at you, it was just a strange way to push an idea. I have also done that once some six years ago and got shot down by some of the old hands here. Which made me appreciate that everybody here is not trying to be smart but rather helpful.
No I do not think so Titinus, my company sells only complete products. The reply is simply to my e-mail because I take an active interest in it as well as being a pet project. The company was established 50 years ago and does a range of products. My commercial audio interest has now shifted completely to ZUS in Canada. Some parts will be manufactured in South Africa some in China and final assembly and marketing will be in Canada
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Let's give them something to talk about....
An externally hosted image should be here but it was not working when we last tested it.
Nothing too radical there, but the devil is in the detail of course...
I take it that in outline at least, that this is the basic topology used.
This is just about the worst I could think of.
A preamp filled up with decoupling caps.
They almost always sound as they look.
Colorful.
Caps are to be avoided, not multiplied.
Absolutely nothing wrong with that topology. Similar to what I and many others use in power amps except for added use NFB. Phase response should be good, THD should be very good.
You mind showing some simulation results?
You mind showing some simulation results?
You say that you have 6dB gain, thus if you have a potentiometer hanging off the front end then the output offset will shift as you change the volume setting, is the the reason for having a servo tocorrecting the offset and how fast does the servo react to changing the volume control, would the speakers not pump in and out?
Actually we have a DC-ajustment on the input (not shown), to ensure that volume does not change DC. The servo takes care of thermaly generated drift and generel DC-offset.Cut off frequency is approx 0,01Hz!
The simulation shows mostly 2. and 3. order, and both less than -100dB at full level. At lower level THD is even lower....
The simulation shows mostly 2. and 3. order, and both less than -100dB at full level. At lower level THD is even lower....
Second harmonic at -100dB is pretty good, where is the noise floor? What is the maximum output swing before clipping?
What is the level in dB of two tone inter-modulation products and what is the phase margin. Also what is the phase at say 30kHz. From this data one can make a definite decision if the pre-amp is good. From you information, so far it is. And when you have answered these questions we all have a good idea of the pre-amp technical specification without giving away any secrets - Thanks.
Nico
Nico
I take it that the input impedance will approximate the resistance of the potentiometer, and I think you say earlier that the output impedance is 200 ohm, correct?
Nico
Nico
Once we have these answers, then the moderators can delete all the cr@p between your first post and the last post since everyone will have an idea of the system specifications of the complete product and all the build details, which is wonderful. Each individual will of course perceive its sound in his/her own individual way, but the objective specification is clear.
Thanks Kurt/Hurtig if this detail was supplied early I do not think that anyone would have asked for a schematic, only those who was curious because there was no other information besides subjective data.
Thanks Kurt/Hurtig if this detail was supplied early I do not think that anyone would have asked for a schematic, only those who was curious because there was no other information besides subjective data.
Hurtig, Kindly share your shunt configuration here, I am very curious to using the RF transistors, it has me thinking, but I cannot figure out why you would do that - I am interested. cannot imagine that you are using them as the actual shunt element as you can only pass a few milli amp. If you consider the S parameters then the transistor is optimized for 50 - 75 ohm. Have you considered using a virtual earth in the system which also helps a lot to making things very spurious free.
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@ Nico Ras:
Have you considered the fact, that we do NOT want to waste time discussing tech specs with you?? You don't have to ask if we considered bla bla for each and every part. We did!
The BFR/BFT are actually used to provide HF gain in the gain stage of the active shunt (And they see a 100ohm load). Hense... they are NOT used as the shunt element. For that we use a 8Amp ON Semi BJT. The shunt actually is a 3 stage design, that ends up with an output impedance in the area of 10milliohm from DC to 10MHz! This makes it possible to use NO decoupling capacitors after the regulator.
Along with the active current source (LM317 in both positive and negative rail), we achieve a theoretical ripple rejection in the audioble frequency range of approx 180dB. In real life, we have not been able to measure any ripple after the regulator.
If you want to build it, go ahead... If you're looking for tech specs discussions only, go for some standard op-amp design.
The more we provide, the more you will ask. That just stopped right this moment. And that's final!
I hope I made myself clear. Have a nice day.
-
Have you considered the fact, that we do NOT want to waste time discussing tech specs with you?? You don't have to ask if we considered bla bla for each and every part. We did!
The BFR/BFT are actually used to provide HF gain in the gain stage of the active shunt (And they see a 100ohm load). Hense... they are NOT used as the shunt element. For that we use a 8Amp ON Semi BJT. The shunt actually is a 3 stage design, that ends up with an output impedance in the area of 10milliohm from DC to 10MHz! This makes it possible to use NO decoupling capacitors after the regulator.
Along with the active current source (LM317 in both positive and negative rail), we achieve a theoretical ripple rejection in the audioble frequency range of approx 180dB. In real life, we have not been able to measure any ripple after the regulator.
If you want to build it, go ahead... If you're looking for tech specs discussions only, go for some standard op-amp design.
The more we provide, the more you will ask. That just stopped right this moment. And that's final!
I hope I made myself clear. Have a nice day.
-
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I give up 
Easy now 😀
The point is, that we just want people to build this preamp if they like and as it is.
We have been trying just about anything possible of tricks, additions, tweaks, power supplies and you just name it.
This is where it ended, and we do not think anymore can be done.
During all this, it have gone through a lot of stages, a lot of prototyping and a lot of experiments.
I.e. in the beginning it had a 2 stage linear PSU with one IC stage followed by fast discrete ones with decoupling caps.
Endless experiments with these caps, showed that there is no good caps anywhere, they are actually bad all of them.
Later on the shunts came in with a fantastic gain in sound quality as a result.
Also a bit more symmetrical topology has been tried out, which actually had a bit lower THD, but this would simply not deliver SQ for some reason forgotten.
So going through all this again, was not the idea.
The point is, that we just want people to build this preamp if they like and as it is.
We have been trying just about anything possible of tricks, additions, tweaks, power supplies and you just name it.
This is where it ended, and we do not think anymore can be done.
During all this, it have gone through a lot of stages, a lot of prototyping and a lot of experiments.
I.e. in the beginning it had a 2 stage linear PSU with one IC stage followed by fast discrete ones with decoupling caps.
Endless experiments with these caps, showed that there is no good caps anywhere, they are actually bad all of them.
Later on the shunts came in with a fantastic gain in sound quality as a result.
Also a bit more symmetrical topology has been tried out, which actually had a bit lower THD, but this would simply not deliver SQ for some reason forgotten.
So going through all this again, was not the idea.
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