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) 706-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 !

[Sendlinger]

Mir ist klar, dass ich hier auf einen bereits 5 Jahre alten thread antworte, aber als Nutzer eines CSV 13 hat man ja zwangsläufig immer noch mit der Frage Umrüstung auf RIAA zu tun.
Man liest überall, wie blöd es gewesen sei, dass Braun auf die auch damals schon ungebräuchliche CCIR Entzerrung statt der gängigen RIAA Entzerrung gesetzt hätte.
Da ich den Verstärker nicht dauerhaft verändern wollte, aber keine falsch entzerrten Platten hören wollte, hab ich mir einen externen heutigen Phono Entzerrer Vorverstärker gekauft und den PCS 5 (mit ShureM44) daran angeschlossen und über den Band Eingang eingespeist.
Einen Unterschied, der nicht nur eingebildet ist, kann ich aber nicht hören. Es sind natürlich auch keine guten Bedingungen, da das Umstecken vom modernen Phono Preamp zum Phono Eingang mit Drehen des Eingangschalters am CSV 13 immer einige Sekunden in Anspruch nimmt. Weil ich weiß, dass die Höhen stärker ausgeprägt sein sollen beim Entzerrer des CSV 13 kann ich mir genau das eventuell einbilden, aber der (eingebildete) wenn überhaupt, Unterschied rechtfertigt für mich keinen Umbau des CSV 13.
Jetzt habe ich aber eine fantastische Seite zu den unterschiedlichen Schneidkennlinien gefunden, die mich ins Grübeln kommen lässt, ob der CSV 13 zumindest in der neueren Ausführung nicht ohnehin korrekt nach RIAA entzerrt.
Hier gibts im Detail alle infos zu den verschiedenen Schneidkennlinien aller Länder, Firmen und Zeiten: https://pspatialaudio.com/record_characters.htm
Braun gibt zwar in seinen Prospekten an, dass ihre Verstärker nach CCIR entzerren, z.B. 1965 hier: https://www.hifi-archiv.info/Braun/1965 ... age/19.jpg
Aber die dort vermerkten Daten entsprechen nicht der aus den 50er Jahren stammenden alten CCIR Norm mit 3180,318 und 50 us sondern bereits einer neueren CCIR Norm mit 3180, 318 und 75us, entsprechen also der DIN 45547 Ausgabe November 1962, die sich damit dem RIAA Standard angepasst hatte. Braun hat ja auch immer viel Wert darauf gelegt, alle Anschlüsse und Vorgaben nach DIN zu erfüllen.
Zitat aus der oben genannten Quelle pspatialaudio.com:" Officially, the German standard for stereophonic LPs was defined in DIN 45547 which was finally adopted in November 1962. This document brought the standard equalisation in line with IEC98 (i.e. RIAA, 3180, 318, 75µs)."
Dieses angeblich viel zu lange Festhalten an der "falschen" Entzerrernorm ist also eventuell nur der Tatsache zu verdanken, dass sich Braun in den Prospektangaben weiterhin auf die CCIR bezogen hat, obwohl die Entzerrung bereits der neuen DIN und damit (auch) RIAA entsprochen hat. (Übrigens auch noch bei CSV 1000, TS 45 u.s.w., später haben sie dazu im Prospekt einfach nichts mehr geschrieben)
Ich bin auf Eure Gedanken dazu gespannt.
Gruß, Sebastian