CSV 13/60 CCIR -> RIAA conversion

[zbyszek]

Hello,

I tried to find information about converting the phono stage equalization curve from CCIR to RIAA.
Unfortunately, the article about restoring and modifying a CSV13 amplifier, which had the necessary information, is no longer available at frihu.com

Does anyone know which capacitors and resistors should be changed, and what values should be used?

Thanks in advance!

[v/d/b]

Hi,
I think if you send frihu an E-Mail, he will give you the schematic.

Kind regards
Thomas

[zbyszek]

Thanks.

I have already received the relevant information from the user Wickerige. I am very grateful for that.

I will post my results when I complete the conversion, so that this topic has any value for the future.

[zbyszek]

I did some research in phono equalisation curves.

I don't know why the curve used in CSV13 is called CCIR, because it is clearly the DIN 45537 standard with 50µsec + 318µsec + 3180µsec time constants.

RIAA has 75µsec + 318µsec + 3180µsec. When we superimpose the RIAA and Braun's CCIR curve, this is what we get:



As you can see, the curves are identical up to 1000kHz, and then the RIAA has a stronger treble boost.

In theory, RIAA records played on CSV13 (remember that the curve is then reversed) will have a boost of mid to high frequencies. However, according to the technical specification of the amplifier, at 20kHz, there is a -3dB drop in high frequencies already, so the difference in mid to high frequencies response resulting from a different equalisation curve is effectively a non-issue.

After listening to several records, I decided to only change the 33kOhm resistor at the signal entry to the standard 47kHz.
I think that other changes in the circuit are not really necessary.

Also, I recommend a complete removal of the loudness filter. Once it is removed, the amplifier will give us a very pleasant and nuanced sound without boomy bass.

The loudness implementation in CSV13 is just awful, compared to e.g. Regie 501k, where loudness effect is quite subtle and very effective.

Here's my CVSV13 in action:

[zbyszek]

Sorry for posting again under my own post.

I have come back to the CCIR > RIAA conversion problem, this time with some SPICE computer modelling.
After many hours of research and testing, I managed to adjust the equalization curve.

This is how the phono stage with RIAA should look.


There are some differences compared to Frihu's solution. However, there is no need to add any elements not present in the original design. You only need to adjust the values of existing elements. There are of course no capacitors with these values. It should be easy to find 33nF and 10nF capacitors which have their actual measured values slightly lower. I was able to pick these from a group of 10 capacitors of each value.

I am also attaching the schematics with other recommended changes, such as reduced input sensitivity and loudness filter deactivated.

CSV13_Schematics_Updated.zip

Modified CSV 13 schematics.

(449.12 KiB) 487-mal heruntergeladen

[Randy]

I did some research in phono equalisation curves.

I don't know why the curve used in CSV13 is called CCIR, because it is clearly the DIN 45537 standard with 50µsec + 318µsec + 3180µsec time constants.

RIAA has 75µsec + 318µsec + 3180µsec. When we superimpose the RIAA and Braun's CCIR curve, this is what we get:



As you can see, the curves are identical up to 1000kHz, and then the RIAA has a stronger treble boost.

In theory, RIAA records played on CSV13 (remember that the curve is then reversed) will have a boost of mid to high frequencies. However, according to the technical specification of the amplifier, at 20kHz, there is a -3dB drop in high frequencies already, so the difference in mid to high frequencies response resulting from a different equalisation curve is effectively a non-issue.

After listening to several records, I decided to only change the 33kOhm resistor at the signal entry to the standard 47kHz.
I think that other changes in the circuit are not really necessary.

Also, I recommend a complete removal of the loudness filter. Once it is removed, the amplifier will give us a very pleasant and nuanced sound without boomy bass.

The loudness implementation in CSV13 is just awful, compared to e.g. Regie 501k, where loudness effect is quite subtle and very effective.

Here's my CVSV13 in action:

Sorry to reply to such an old post ! Do you still have these pictures? They don't seem to load anymore on the page.

[Paparierer]

Hi Randy,
flickr doesn't seem to host the pictures any more.
You'll have to ask Zbyszek for them...

Yours, Gereon

[Randy]

Hi Randy,
flickr doesn't seem to host the pictures any more.
You'll have to ask Zbyszek for them...

Yours, Gereon

I have messaged him, thanks! This topic did not seem very active anymore. I'm struggling with the same question because I only have records with RIAA standard at home and nothing at all with CCIR standard. But it's too difficult for me to do myself, I would need to pay someone else to do it and I don't know if the sound improvement benefits the costs I would need to pay someone to do it. I think I will start a new topic if that's ok with the moderators.

Thanks !