Yamaha synth-expression circuit

omissis · 1st November 2006, 12:23 PM

Hi all, first post here.
Please look at this picture

It comes from a Yamaha polysynth; I'm studying this circuit, namely the PH1 and PH2 sections and I'd like to know :

1.Is it a kind of a loudness correction circuit?

2.How the two serial filters interact with the photo resistor?

3.Is that embedding able to make the filters change their slope according to the frequency of the fundamental? This is the main question: on this Yamaha polysynth , if you dropped the pitch down to very low pitches with a ribbon controller the sound became more "filtered" in a continuous way...someone told me that there may be a slope variation from 3dB to 12dB shelf and this may be related with the action of the Vactrol itself which controls the pedal too...
I wish for a simple yet precise explaination of how this circuit works, I'd like to try to build it when my skills will grow .
Thx for your care.

omissis · 2nd November 2006, 10:50 AM

Hi
Bumping in. Anybody able to give me any explaination??

omissis · 2nd November 2006, 10:50 AM

Excuse me, this topic relates to a musical instrument no doubt but may be a general question about amplification, I'm not really skilled in electronics. Moderators, is this the right place to have any explaination about the questions I put in my first post?
Thx for any reply

Sonusthree · 7th November 2006, 03:57 PM

The picture will not load on my computer.
Maybe that is why?
It tries for ages but then nothing happens. (With Opera and I.E.)

omissis · 7th November 2006, 09:11 PM

You can find the picture here , I have an OLD computer with IE6 so you can try even to download the picture by right clicking on the link then clicking on "Save object as"....

Thanks a lot for your reply..

Sonusthree · 8th November 2006, 10:47 AM

Still not working here.
I have even tried a different computer.

Can anyone else see the link or is just me?

Optical · 8th November 2006, 08:50 PM

picture works fine for me and always has.. cant answer your question though

omissis · 16th November 2006, 08:14 AM

*bump*

Any people here can enlighten me about the questions I asked on my first post??
Please, this means lot to me!
M

Vele · 20th November 2006, 06:32 AM

Is that Yamaha DX7?

omissis · 20th November 2006, 08:43 AM

No, it comes from a Yamaha CS80, the same circuit is embedded also into the CS50 and CS60 : can you answer to the questions on the first post? Moreover does this kind of embedding give sort of a soft distortion??
Thanks!!!

1st November 2006, 12:23 PM	#1
omissis diyAudio Member Join Date: Nov 2006	Yamaha synth-expression circuit Hi all, first post here. Please look at this picture It comes from a Yamaha polysynth; I'm studying this circuit, namely the PH1 and PH2 sections and I'd like to know : 1.Is it a kind of a loudness correction circuit? 2.How the two serial filters interact with the photo resistor? 3.Is that embedding able to make the filters change their slope according to the frequency of the fundamental? This is the main question: on this Yamaha polysynth , if you dropped the pitch down to very low pitches with a ribbon controller the sound became more "filtered" in a continuous way...someone told me that there may be a slope variation from 3dB to 12dB shelf and this may be related with the action of the Vactrol itself which controls the pedal too... I wish for a simple yet precise explaination of how this circuit works, I'd like to try to build it when my skills will grow . Thx for your care.

7th November 2006, 03:57 PM	#4
Sonusthree diyAudio Member Join Date: Dec 2005 Location: Brighton,UK	The picture will not load on my computer. Maybe that is why? It tries for ages but then nothing happens. (With Opera and I.E.) __________________ Martin + + =

8th November 2006, 10:47 AM	#6
Sonusthree diyAudio Member Join Date: Dec 2005 Location: Brighton,UK	Still not working here. I have even tried a different computer. Can anyone else see the link or is just me? __________________ Martin + + =

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2nd November 2006, 10:50 AM	#2
omissis diyAudio Member Join Date: Nov 2006	Hi Bumping in. Anybody able to give me any explaination??

7th November 2006, 09:11 PM	#5
omissis diyAudio Member Join Date: Nov 2006	You can find the picture here , I have an OLD computer with IE6 so you can try even to download the picture by right clicking on the link then clicking on "Save object as".... Thanks a lot for your reply..

8th November 2006, 08:50 PM	#7
Optical diyAudio Member Join Date: Nov 2002 Location: Auckland, New Zealand	picture works fine for me and always has.. cant answer your question though

16th November 2006, 08:14 AM	#8
omissis diyAudio Member Join Date: Nov 2006	bump Any people here can enlighten me about the questions I asked on my first post?? Please, this means lot to me! M

20th November 2006, 06:32 AM	#9
Vele diyAudio Member Join Date: Jan 2006 Location: Home, 2nd floor	Is that Yamaha DX7?

20th November 2006, 08:43 AM	#10
omissis diyAudio Member Join Date: Nov 2006	No, it comes from a Yamaha CS80, the same circuit is embedded also into the CS50 and CS60 : can you answer to the questions on the first post? Moreover does this kind of embedding give sort of a soft distortion?? Thanks!!!

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