Hi Bill,
I'd like more info on the Hans build you speak of. Will it work for a flat phono circuit? I already have the Wayne Kirkwood balanced flat phono built, which is why I was thinking capacifier for it. It looks like the level 1 capacifier is unnecessary for the Grace if I keep the cable capacitance low enough. For the mmc2 there may be some benefit from a capacifier? Level 2 capacifier is totally different. Need more info and maybe that spreadsheet they used to have. I am willing to modify the Aurak circuits for the mmc2 if I knew the new schema values.
The Capacifier level one had some issues with 'effective cartridge inductance' being lower than measured or spec'd inductance. I was thinking of making a switch that would give it different R loads, tune it by ear.
I'd like more info on the Hans build you speak of. Will it work for a flat phono circuit? I already have the Wayne Kirkwood balanced flat phono built, which is why I was thinking capacifier for it. It looks like the level 1 capacifier is unnecessary for the Grace if I keep the cable capacitance low enough. For the mmc2 there may be some benefit from a capacifier? Level 2 capacifier is totally different. Need more info and maybe that spreadsheet they used to have. I am willing to modify the Aurak circuits for the mmc2 if I knew the new schema values.
The Capacifier level one had some issues with 'effective cartridge inductance' being lower than measured or spec'd inductance. I was thinking of making a switch that would give it different R loads, tune it by ear.
Bob's article where he discusses damped RIAA is here Linear Audio | your tech audio resource and well worth €2.99 to download.
@Pawel, a zero is a resistor in series with the HF RIAA capacitor. Are you talking about a particular circuit you want to modify?
@Pawel, a zero is a resistor in series with the HF RIAA capacitor. Are you talking about a particular circuit you want to modify?
Back from Venice, having rowed the fantastic VogaLonga, I see your postings but still do not fully get what you are asking.
Do you want the balanced Aurak be adapted for a 200mH / 800 Ohm cart ?
And what about the flat Wayne amp. Are you planning to use a capacifier that is reducing the Cart's output to MC level first ?
In that case using the Aurak in combination would be a total mismatch.
Hans
Hans, thanks.
I am really questioning the value of a capacifier in front of the WK flat phono. If I am going to get system cable capacitance down as low as I think most of the electrical resonances can be moved up and out of the audio range. Mechanical resonances, from the cartridge contribution, Comes down to cantilever material? Still the level 1 capacifier does show some benefit for my B&O mmc2 if that total capacitance is above 150mH or so. For the Grace cart it would have to be higher. Once the audible advantages from a capacifier are removed with lower capacitance, what other advantages are left? Couldn't those advantages, if they exist, be delt with in the digital domain?
Regarding any changes to the Aurak for my B&O mmc2? I think I would have to change too many components, but I am curious.
BTW it measures 215mH and 780ohm
I am really questioning the value of a capacifier in front of the WK flat phono. If I am going to get system cable capacitance down as low as I think most of the electrical resonances can be moved up and out of the audio range. Mechanical resonances, from the cartridge contribution, Comes down to cantilever material? Still the level 1 capacifier does show some benefit for my B&O mmc2 if that total capacitance is above 150mH or so. For the Grace cart it would have to be higher. Once the audible advantages from a capacifier are removed with lower capacitance, what other advantages are left? Couldn't those advantages, if they exist, be delt with in the digital domain?
Regarding any changes to the Aurak for my B&O mmc2? I think I would have to change too many components, but I am curious.
BTW it measures 215mH and 780ohm
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In principle, all filtering performed in the analogue domain, either passive or active, can also be dealt with in the digital domain.
You only have to change two resistors in the Aurak amp to get Rext = (4xLcart-Rcart), simple as that.Regarding any changes to the Aurak for my B&O mmc2? I think I would have to change too many components, but I am curious.
You seem to be torn between too many options, just make a choice for one of them or you might go astray.
Hans
@Mcspack: Hans is right, beware of chasing too many things at once. I nearly fell into that trap. The capacifier sort of ground to a halt in terms of development about 7 years ago so you are on your own and breaking new ground. The two Aurak versions, whilst still new ground is at least in use by >1 person and Hans has a very good spice model to help out (thank you again for that Hans).
We may still find the mythical resonances we are looking for with this in which case additional corrections may be required of course
We may still find the mythical resonances we are looking for with this in which case additional corrections may be required of course
Thanks Hans,
Yes This thread and that old capacifier thread can get confusing. I was looking at pages 21 and 37 of this thread where LD spoke of changes to make to the SE Aurak if you wanted to use it for rare r1=3*L-Rc carts. His post on page 37 mentions 5 components(per side) to change. Extending that to the TP would be over 20 components, or so I thought. If you are saying only two resistors per side is all I'd need to change? That is great news! Fortunately I only have two very good MMs to build preamps for.
I also have a strain gauge cart but that is a whole different conversation, lol.
Yes This thread and that old capacifier thread can get confusing. I was looking at pages 21 and 37 of this thread where LD spoke of changes to make to the SE Aurak if you wanted to use it for rare r1=3*L-Rc carts. His post on page 37 mentions 5 components(per side) to change. Extending that to the TP would be over 20 components, or so I thought. If you are saying only two resistors per side is all I'd need to change? That is great news! Fortunately I only have two very good MMs to build preamps for.
I also have a strain gauge cart but that is a whole different conversation, lol.
Sorry, but what is a TP Aurak ?
What are the two MM that you are planning to use, Lcart and Rcart.
If not to far apart, you built your Aurak version and al that has to be changed are the two resistors in series with the cart when changing Carts.
Hans
Here is your version for the Balanced Aurak.
With the B&O Cart use 2*40 Ohm and for the Grace 2*610 Ohm or (2*570 +2*40).
Attachments
I suppose I’m going to come across as touchy but the balanced Aurak is actually kind of a group effort. As laid out in post #205 on pg. 21 of this thread (where the original balanced Aurak schematic was posted by me), I took the original Aurak schematic as posted by LuckyDog on VE and collaborated with a forum member on Audicircle (Poty) to create a balanced iteration of it. After I posted the circuit here, Hans took to it and further refined it, for which I am very grateful.
It was not posted with the intention of driving business to Twisted Pear or anyone else for that matter. If I had any skill designing PCBs, I would have made it an open project on OSHPark for anyone to order. I have thought about commissioning someone to do this but it’s just not a priority for me until other projects are out of the way.
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Fair comment, but IMO calling it the 'TP' Aurak is valid as it is based on ready to buy boards from TP and using their servo. This is not optimal from a number of standpoints and was only to get a couple of balanced boards into the wild, which have been delayed for other reasons (she turns 1 tomorrow in my case).
As we learn more about the practicalities and find more odd cartridges that need changes to the network then we might end up homing in on a better design for both SE and balanced and maybe get some open source boards run out (if LD approves).
The 'TP' is just one variant, not the one true solution
As we learn more about the practicalities and find more odd cartridges that need changes to the network then we might end up homing in on a better design for both SE and balanced and maybe get some open source boards run out (if LD approves).
The 'TP' is just one variant, not the one true solution
You are right to have published the first Balanced Aurak in this thread, being nothing but a double SE Aurak no more or less.
But noise performance was bad and so was CMRR, being the most important parameter when going balanced, etc, etc.
See posting #331.
The completely different TP solution was yet another sort of balanced "Aurak" version, attractive because an existing PCB could be used.
You give the impression to be the inventor of the balanced Aurak preamp, not being happy that your design has been transferred to TP.
Well Balanced phono preamps are there for many, many years, and although the name Aurak came from LD, the idea behind virtual gnd input circuits goes back many years also.
Anybody may claim or use anything that I have published so far, but please do not give the impression that I misused your ideas.
Hans