Hi, I kindly ask if you can tell me the best RIAA inverse circuit, the most reliable, to make to do some tests on my tube phono preamp.
I would use it with a Analogic Wien frequency generator with 600ohm output and with a frequency generator of a USB oscilloscope whose output impedance I don't know.
Thanks a lot! 😀
I would use it with a Analogic Wien frequency generator with 600ohm output and with a frequency generator of a USB oscilloscope whose output impedance I don't know.
Thanks a lot! 😀
Do you know how to google?
A simple answer will present you dozens of circuits.
If you do such an advanced project and have the data of your measurement equipment,
you will know how to choose a fitting circuit as well.
This is not for beginners in audio, so better know how to do this. Without any knowledge and just a forum question, the result won't be reached.
Maybe even google is too much for you, thats the way it is today. Lazy audio designers go and let a forum do the work, because they are very clever and know how to put others to work.😀
A simple answer will present you dozens of circuits.
If you do such an advanced project and have the data of your measurement equipment,
you will know how to choose a fitting circuit as well.
This is not for beginners in audio, so better know how to do this. Without any knowledge and just a forum question, the result won't be reached.
Maybe even google is too much for you, thats the way it is today. Lazy audio designers go and let a forum do the work, because they are very clever and know how to put others to work.😀
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Yes I know google, but for the very reason that there are so many different options I was wondering which was the good one.
I'm not asking to do the job. I hardly know the specifications of my Wien generator and my usb oscilloscope.
In fact I don't know the output impedance of the oscilloscope. So so little.
I just wanted to make a known reverse RIAA to be valid and see what comes out of it.
I'm not lazy at all, I asked for advice because the selection of a decent reverse riaa is like a jungle.
So the forum is just for asking what?
Nobody is obliged to answer. Take it into consideration.
Anyway thanks.
I'm not asking to do the job. I hardly know the specifications of my Wien generator and my usb oscilloscope.
In fact I don't know the output impedance of the oscilloscope. So so little.
I just wanted to make a known reverse RIAA to be valid and see what comes out of it.
I'm not lazy at all, I asked for advice because the selection of a decent reverse riaa is like a jungle.
So the forum is just for asking what?
Nobody is obliged to answer. Take it into consideration.
Anyway thanks.
You know what a forum is for, and we both know that it seems that five minutes online search for the basic invers RIAA circuits were too much of an afford for you.
Children in primary school learn how to distinguish between relevant in irrelevant informations today. Of course, google always present many choices.
So show us what you have found and we can tell you what will fit.
Otherwise, it applies correctly what I assumed. Too lazy to do the search for himself.
Children in primary school learn how to distinguish between relevant in irrelevant informations today. Of course, google always present many choices.
So show us what you have found and we can tell you what will fit.
Otherwise, it applies correctly what I assumed. Too lazy to do the search for himself.
If you have 50Ohm generator (or soundcard) output:
http://hifisonix.com/wordpress/wp-content/uploads/2016/12/Accurate-Inverse-RIAA.pdf
http://hifisonix.com/wordpress/wp-content/uploads/2016/12/Accurate-Inverse-RIAA.pdf
Thanks for the replies.
I have now checked the specifications of the generator inside the usb oscilloscope. He says it's 200ohm.
The other generator I use, perhaps more often, is the Wien which is 600ohm.
I was indices between the one shown to me by Euro21, which I had already seen online (interesting but is Only good for 50ohm generators?) and this one of which I am attaching the pdf.
Of the pdf I did not understand if I should apply the scheme "Fig.3" or "Fig.4" and what exact values of the components as they are complex technical issues and I am not a native English speaker.
A question arises.... Can't the inverse riaa circuit that I am going to make work with both generators I have since they have different output impedances?
If I want to use both (generator) of them, do I have to create two different "inverse riaa"?
Unfortunately I don't have a 50ohm output.
Thanks Rayma for the mentioned kit, but work on 50ohm signal generator output.
Although I have no experience but it seems to me a bit minimal-standard ... It gives me the feeling of inaccurate ... which I guess doesn't mean much but this makes me suspect.
It doesn't matter if it's a kit ... I assemble it independently.
Anyway thanks.
I have now checked the specifications of the generator inside the usb oscilloscope. He says it's 200ohm.
The other generator I use, perhaps more often, is the Wien which is 600ohm.
I was indices between the one shown to me by Euro21, which I had already seen online (interesting but is Only good for 50ohm generators?) and this one of which I am attaching the pdf.
Of the pdf I did not understand if I should apply the scheme "Fig.3" or "Fig.4" and what exact values of the components as they are complex technical issues and I am not a native English speaker.
A question arises.... Can't the inverse riaa circuit that I am going to make work with both generators I have since they have different output impedances?
If I want to use both (generator) of them, do I have to create two different "inverse riaa"?
Unfortunately I don't have a 50ohm output.
Thanks Rayma for the mentioned kit, but work on 50ohm signal generator output.
Although I have no experience but it seems to me a bit minimal-standard ... It gives me the feeling of inaccurate ... which I guess doesn't mean much but this makes me suspect.
It doesn't matter if it's a kit ... I assemble it independently.
Anyway thanks.
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If you see Hagerman type iRIAA schematic, the 50R generator and the 1k91 resistor connected serial, the sum is 1960R.
If you have 600R generator, use 1960-600= 1360R resistor as R5.
If you have 600R generator, use 1960-600= 1360R resistor as R5.
Ok thank you very much euro21 and Rayma.
I try to recover the necessary components. I will create two circuits (stereo), I put everything in a tin box, and with switches and relative R5 resistance calculate, I will prepare for 3 input impedances, 600ohm, 200ohm and for a future new standard 50ohm generator (which I want to buy) .
What kind of dielectric is recommended for capacitors?
Thanks again.
Hope it works trusted and reliable.
Good night and / or good afternoon.
I try to recover the necessary components. I will create two circuits (stereo), I put everything in a tin box, and with switches and relative R5 resistance calculate, I will prepare for 3 input impedances, 600ohm, 200ohm and for a future new standard 50ohm generator (which I want to buy) .
What kind of dielectric is recommended for capacitors?
Thanks again.
Hope it works trusted and reliable.
Good night and / or good afternoon.
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Note that the 50kHz 'Neumann pole' is (largely) a myth.
The SAL74 (which is the canonical Neumann cutting amplifier chain) does have a 2 pole Sallen and key filter at approximately 50kHz at the input of the program equaliser (Slightly peaky at that!), and there is a roll off somewhere up at about a 100kHz due to the opamp used in the original running out of GBP, but there is no single pole as such. The revised SAL74A replaced that part with 5534s which provided rather more GBP.
The program equaliser also has what amounts to a Baxandall type tone control built in (Normally used to try to compensate the spring back in the acetate masters) so the curves were never that exact to start with.
Incidentally, the acceleration and velocity limiter card is anything but linear phase, it is all over the shop, and you do NOT bypass that when cutting.
There is approximately no point in getting overly picky about RIAA curves because the lathe operators never did!
The Lipshitz circuit for a passive IRIAA is quite sufficient for testing preamps and such like and is easily built in a little diecast box.
The SAL74 (which is the canonical Neumann cutting amplifier chain) does have a 2 pole Sallen and key filter at approximately 50kHz at the input of the program equaliser (Slightly peaky at that!), and there is a roll off somewhere up at about a 100kHz due to the opamp used in the original running out of GBP, but there is no single pole as such. The revised SAL74A replaced that part with 5534s which provided rather more GBP.
The program equaliser also has what amounts to a Baxandall type tone control built in (Normally used to try to compensate the spring back in the acetate masters) so the curves were never that exact to start with.
Incidentally, the acceleration and velocity limiter card is anything but linear phase, it is all over the shop, and you do NOT bypass that when cutting.
There is approximately no point in getting overly picky about RIAA curves because the lathe operators never did!
The Lipshitz circuit for a passive IRIAA is quite sufficient for testing preamps and such like and is easily built in a little diecast box.
Hi,
You want at least one item You can rely on. The lazyness of lathe operators is no excuse nor reason to do the same imho.
iRIAA shows the network I'm using since long. Similar to bonsai's its a high precision network, unlike the kit and RodElliot's, and allows for switching of different generator output impedances and between MM and MC output level.
Last year I redesigned the PCB with SMD parts and additional internal screen.
Building very small and adding screening is advantageous here as it reduces air-bound noise disturbing the delicate signal.
jauu
Calvin
You want at least one item You can rely on. The lazyness of lathe operators is no excuse nor reason to do the same imho.
iRIAA shows the network I'm using since long. Similar to bonsai's its a high precision network, unlike the kit and RodElliot's, and allows for switching of different generator output impedances and between MM and MC output level.
Last year I redesigned the PCB with SMD parts and additional internal screen.
Building very small and adding screening is advantageous here as it reduces air-bound noise disturbing the delicate signal.
jauu
Calvin
It wasn't 'laziness'. There was a distinct job called Mastering Engineer whose function it was to make the resulting vinyl sound as good as possible given the cutter &c., and also to enforce the company sound, e.g. RCA, Decca. This is one of many reasons why CD reissues of LPs never sound the same.
I use the inverse RIAA (‘IRN’) below for testing all my RIAA designs as well as a QA401 analyzer that has the inverse RIAA as a plug-in
An Accurate Inverse RIAA Network
A good way to test the conformance of a RIAA is to drive the IRN with a square wave. You get spikes out of the IRN (looks really weird on a scope) which after passing through the RIAA preamp, restores them back to a square wave.
This test is very sensitive, since you can see slight anomalies as over shoot (when the response goes up at HF), strange rise/ fall time shapes (mid-band response problems) and sloping top/bottoms at LF due to either boost or drop off.
You should test at 100 Hz, 1K and 10k. There’s a bit of a discussion in the pdf (circuit, BOM etc) you can down load in the link.
An Accurate Inverse RIAA Network
A good way to test the conformance of a RIAA is to drive the IRN with a square wave. You get spikes out of the IRN (looks really weird on a scope) which after passing through the RIAA preamp, restores them back to a square wave.
This test is very sensitive, since you can see slight anomalies as over shoot (when the response goes up at HF), strange rise/ fall time shapes (mid-band response problems) and sloping top/bottoms at LF due to either boost or drop off.
You should test at 100 Hz, 1K and 10k. There’s a bit of a discussion in the pdf (circuit, BOM etc) you can down load in the link.
Thanks Calvin, I had read the article a few days ago while looking for iRIAA solutions.
Then I abandoned the idea because it was smd, but I had thought of realizing it in the THT version on a "base 1000 holes", I don't know what the "base 1000 holes" is called abroad, but in Italy it's called that!
For me, working with smd is "uncomfortable" and complicated and difficult to acquire the components.
I saw that there are gerber files but ..hummm..nn I know if you can print at a good price given the size and format.
I'll think about it '. Do you still have gerber of the old type, the THT one, on your hands?
This in the image.
I would like to create a stereo version one and this with also input impedance switching and the rest .. it's a great solution!
Have you always made it like the smd one?
Great job and you are very kind to offer the gerber! 🙂
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I'm still here! I was in a bit of a hurry, I opened the drawer and I had everything I needed to make a first prototype.
I'll do a second to use in "stereo" then put them in a metal box that I have. Sure it's not as nice as the SMD version, it may not be as quiet as the SMD version, but in the meantime I can use it.
Maybe the SMD version will be soon.
I used ultra-precise mica caps which I selected and matched as I did for the resistors.
The values are, for both, identical and perfect, super perfect.
It may be that the solders are not ideal as for the SMD version, it may be that it is better to have all the components soldered instead of the input R on the pin header.
But after all, the header pins have never betrayed me even in "delicate" applications.
In the meantime, it's ok like that. 😀
I have a question. I have set up to use three different inputs, as per diagram.
The 50ohm for me is ok because I will soon buy a generator that comes out at 50ohm for sure. The other impedances I have are a Wien oscillator, which I measured with a multimeter and is (declared 600ohm) 562ohm. The other generator I use it with is built into a USB oscilloscope (claimed 200ohm), measured in 163.3ohm. Now I have to calculate the input resistances for these three values:
1) 50ohm (future generator)
2) 562ohm - Wien Generator
3) 164.3ohm - USB Oscilloscope/Generator
I guess the 1.33k R and the 30ohm R remain the ones in the schematic.
I thought about doing this, I know the question is elementary but I would like to be sure. Basically I have to put the same resistance value, equal to the R out of the generator, in parallel to the iRIAA input, I think. I would use 3 bnc for the 3 inputs (6 in stereo mode) and a switch (double in stereo mode) with three positions that switches me only the "hot pole". It's correct? How did you do that they have saved many connectors!
Here is a drawing of a first grade school boy... 😱
Thanks again!!!
Thanks again!!!
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My previous post contains totally wrong calculations.
What I have to do for the output impedances of the different generators is this:
Generator Impedance + R (resistance that I put in series with the generator, and NOT in parallel) = 600ohm
The sum of the impedance of the generator + all the R of the circuit, before entering the network, must be 1960ohm.
Is correct?
Thanks
What I have to do for the output impedances of the different generators is this:
Generator Impedance + R (resistance that I put in series with the generator, and NOT in parallel) = 600ohm
The sum of the impedance of the generator + all the R of the circuit, before entering the network, must be 1960ohm.
Is correct?
Thanks
