Hi guys,

It's been a while since I've been in the Csound loop but nevertheless I now
have to use it to build my own reverb unit. I know that I have to feedback
the same signal with a certain delay time and with slightly more attenuation
each time for x amount of times. I was just on the look out for any good
advice from someone who has done this before.

I am planning to use a vdelay to feed the signal back through and attenuate
it. Now, considering what I ultimately want is a slider controlling
something comparable to room size and one for reflectivity, density and
maybe high/low cut (fairly simple) what would you suggest as being the
sensible opcodes and methods? 

I'm comparatively inexperienced so please, any suggestions will do.

Thanks very much,

Doug
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And if you do not lik ethat, there is a set of 28 reverbs collected by
Josep (I think it was,or Hans?) that are all in csound.  Cannot put my
mouse on them at present, but I do play them to teh students.  Look on
csounds.com


> Hello Doug,
>
> If you don't *have* to build it yourself, maybe you could take a look
> at the existing reverb opcodes, for example "screverb" is a pretty
> nice reverb.
>
> best
> Oeyvind
>
> 2008/12/1 basshead6949 :
>>
>> Hi guys,
>>
>> It's been a while since I've been in the Csound loop but nevertheless I
>> now
>> have to use it to build my own reverb unit. I know that I have to
>> feedback
>> the same signal with a certain delay time and with slightly more
>> attenuation
>> each time for x amount of times. I was just on the look out for any good
>> advice from someone who has done this before.
>>
>> I am planning to use a vdelay to feed the signal back through and
>> attenuate
>> it. Now, considering what I ultimately want is a slider controlling
>> something comparable to room size and one for reflectivity, density and
>> maybe high/low cut (fairly simple) what would you suggest as being the
>> sensible opcodes and methods?
>>
>> I'm comparatively inexperienced so please, any suggestions will do.
>>
>> Thanks very much,
>>
>> Doug
>> --
>> View this message in context:
>> http://www.nabble.com/Building-my-own-reverb-unit-tp20769912p20769912.html
>> Sent from the Csound - General mailing list archive at Nabble.com.
>>
>>
>>
>> Send bugs reports to this list.
>> To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe
>> csound"
>>
>
>
> Send bugs reports to this list.
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> csound"
>
>
>

Thanks for the speed reply guys. I was already previously aware of the many
reverb opcodes (not heard of screverb though so thanks for the tip!) but in
actual fact, yes I do have to build it myself so using reverb opcodes is not
an option. There's no real strict specification on what I can use, just
those that I can't. From what  know, I just assumed a variable delay would
be the best option. Any more ideas?

Doug



Oeyvind Brandtsegg-2 wrote:
> 
> Hello Doug,
> 
> If you don't *have* to build it yourself, maybe you could take a look
> at the existing reverb opcodes, for example "screverb" is a pretty
> nice reverb.
> 
> best
> Oeyvind
> 
> 2008/12/1 basshead6949 :
>>
>> Hi guys,
>>
>> It's been a while since I've been in the Csound loop but nevertheless I
>> now
>> have to use it to build my own reverb unit. I know that I have to
>> feedback
>> the same signal with a certain delay time and with slightly more
>> attenuation
>> each time for x amount of times. I was just on the look out for any good
>> advice from someone who has done this before.
>>
>> I am planning to use a vdelay to feed the signal back through and
>> attenuate
>> it. Now, considering what I ultimately want is a slider controlling
>> something comparable to room size and one for reflectivity, density and
>> maybe high/low cut (fairly simple) what would you suggest as being the
>> sensible opcodes and methods?
>>
>> I'm comparatively inexperienced so please, any suggestions will do.
>>
>> Thanks very much,
>>
>> Doug
>> --
>> View this message in context:
>> http://www.nabble.com/Building-my-own-reverb-unit-tp20769912p20769912.html
>> Sent from the Csound - General mailing list archive at Nabble.com.
>>
>>
>>
>> Send bugs reports to this list.
>> To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe
>> csound"
>>
> 
> 
> Send bugs reports to this list.
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> 

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Aaah this is more like it... I am a bit rusty on comb filters but have just
checked them out and think I get it. Would you suggest a feedback or
feedforward system? Also, which opcodes should I use for the comb/allpass
filters? By what I can figure out, an allpass filter simply shifts the phase
of its input by 90º. Looking at the example webpage supplied by Oeyvind
(Merci!), 

http://www.dsprelated.com/dspbooks/pasp/Freeverb.html 

I can see there are 4 allpass filters at the output, I trust this is no
coincidence. What are they doing with respect to the output reverberation?
I'm not clear why they are necessary.

Thanks for all the speedy help so far!

Doug



Iain McCurdy wrote:
> 
> 
> A digital reverb, in the mould of Schroeder or Moorer (google these
> names), can be designed using comb and all pass filters; Csound has plenty
> of these but if you want you can model comb and all pass filters using
> delay opcodes. The secret to creating a smooth reverb effect will be to
> choose appropriate values for delay (loop) time for the delays/filters -
> if you choose the wrong values you will either get discernible echoes or
> ringing sounds (or both). Have a look at the documention and example for
> the nreverb opcode as this will give you some clues as where to start.
> Bye, Iain
> 
>> Date: Mon, 1 Dec 2008 03:09:07 -0800
>> From: basshead6949@hotmail.com
>> To: csound@lists.bath.ac.uk
>> Subject: [Csnd]  Building my own reverb unit
>> 
>> 
>> Hi guys,
>> 
>> It's been a while since I've been in the Csound loop but nevertheless I
>> now
>> have to use it to build my own reverb unit. I know that I have to
>> feedback
>> the same signal with a certain delay time and with slightly more
>> attenuation
>> each time for x amount of times. I was just on the look out for any good
>> advice from someone who has done this before.
>> 
>> I am planning to use a vdelay to feed the signal back through and
>> attenuate
>> it. Now, considering what I ultimately want is a slider controlling
>> something comparable to room size and one for reflectivity, density and
>> maybe high/low cut (fairly simple) what would you suggest as being the
>> sensible opcodes and methods? 
>> 
>> I'm comparatively inexperienced so please, any suggestions will do.
>> 
>> Thanks very much,
>> 
>> Doug
>> -- 
>> View this message in context:
>> http://www.nabble.com/Building-my-own-reverb-unit-tp20769912p20769912.html
>> Sent from the Csound - General mailing list archive at Nabble.com.
>> 
>> 
>> 
>> Send bugs reports to this list.
>> To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe
>> csound"
> 
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No no please keep going! It's all starting to make a little more sense. Can
you explain why the phase shift on the all pass's are needed Oeyvind? I'm
not quite sure how it would be applicable with respect to delays...

Doug


Oeyvind Brandtsegg-2 wrote:
> 
> The allpasses are IIR, that is, they use feedback, this way you can
> "lengthen" the sound without attenuating any frequencies, (trying a
> simple explanation on something a little bit more complex). The comb
> filters in freeverb are feedforward afaik, I'm not sure why feedback
> is not used there as well, except maybe the metallic "comb" sound may
> get too present in the output with significant feedback. Good luck, if
> you go for this reverb architecture (well, any architecture really) ,
> good results lay in fine tuning the different filters in relation to
> each other. It is very easy to get a metallic ringing reverb even with
> a good architecture like this one...
> 
> sounds like you're working on an assignment, so I'll shut up now
> Oeyvind
> 
> 2008/12/1 basshead6949 :
>>
>> Aaah this is more like it... I am a bit rusty on comb filters but have
>> just
>> checked them out and think I get it. Would you suggest a feedback or
>> feedforward system? Also, which opcodes should I use for the comb/allpass
>> filters? By what I can figure out, an allpass filter simply shifts the
>> phase
>> of its input by 90º. Looking at the example webpage supplied by Oeyvind
>> (Merci!),
>>
>> http://www.dsprelated.com/dspbooks/pasp/Freeverb.html
>>
>> I can see there are 4 allpass filters at the output, I trust this is no
>> coincidence. What are they doing with respect to the output
>> reverberation?
>> I'm not clear why they are necessary.
>>
>> Thanks for all the speedy help so far!
>>
>> Doug
>>
>>
>>
>> Iain McCurdy wrote:
>>>
>>>
>>> A digital reverb, in the mould of Schroeder or Moorer (google these
>>> names), can be designed using comb and all pass filters; Csound has
>>> plenty
>>> of these but if you want you can model comb and all pass filters using
>>> delay opcodes. The secret to creating a smooth reverb effect will be to
>>> choose appropriate values for delay (loop) time for the delays/filters -
>>> if you choose the wrong values you will either get discernible echoes or
>>> ringing sounds (or both). Have a look at the documention and example for
>>> the nreverb opcode as this will give you some clues as where to start.
>>> Bye, Iain
>>>
>>>> Date: Mon, 1 Dec 2008 03:09:07 -0800
>>>> From: basshead6949@hotmail.com
>>>> To: csound@lists.bath.ac.uk
>>>> Subject: [Csnd]  Building my own reverb unit
>>>>
>>>>
>>>> Hi guys,
>>>>
>>>> It's been a while since I've been in the Csound loop but nevertheless I
>>>> now
>>>> have to use it to build my own reverb unit. I know that I have to
>>>> feedback
>>>> the same signal with a certain delay time and with slightly more
>>>> attenuation
>>>> each time for x amount of times. I was just on the look out for any
>>>> good
>>>> advice from someone who has done this before.
>>>>
>>>> I am planning to use a vdelay to feed the signal back through and
>>>> attenuate
>>>> it. Now, considering what I ultimately want is a slider controlling
>>>> something comparable to room size and one for reflectivity, density and
>>>> maybe high/low cut (fairly simple) what would you suggest as being the
>>>> sensible opcodes and methods?
>>>>
>>>> I'm comparatively inexperienced so please, any suggestions will do.
>>>>
>>>> Thanks very much,
>>>>
>>>> Doug
>>>> --
>>>> View this message in context:
>>>> http://www.nabble.com/Building-my-own-reverb-unit-tp20769912p20769912.html
>>>> Sent from the Csound - General mailing list archive at Nabble.com.
>>>>
>>>>
>>>>
>>>> Send bugs reports to this list.
>>>> To unsubscribe, send email sympa@lists.bath.ac.uk with body
>>>> "unsubscribe
>>>> csound"
>>>
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>>
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>> View this message in context:
>> http://www.nabble.com/Building-my-own-reverb-unit-tp20769912p20772188.html
>> Sent from the Csound - General mailing list archive at Nabble.com.
>>
>>
>>
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Oeyvind Brandtsegg wrote:
> The allpasses are IIR, that is, they use feedback, this way you can
> "lengthen" the sound without attenuating any frequencies, (trying a
> simple explanation on something a little bit more complex). The comb
> filters in freeverb are feedforward afaik, I'm not sure why feedback
> is not used there as well, except maybe the metallic "comb" sound may
> get too present in the output with significant feedback. Good luck, if
> you go for this reverb architecture (well, any architecture really) ,
> good results lay in fine tuning the different filters in relation to
> each other. It is very easy to get a metallic ringing reverb even with
> a good architecture like this one...

... dropping in to this discussion. Are you saying the art of designing 
a good reverb is to get it beyond 'metallic ringing'. I 've always found 
the classic Csound reverbs a bit metallic and I thought designing your 
own filter means to get it beyond 'metallic'.

Furter, I recall a collection of very steep ("brick wall, 4 pole 
allpass" ?) filters on Csound.com, in the early days of version 3.58. 
Never tried it out.

Ludo

Hello,

Oeyvind, regarding this link's diagram of the parallel and series filters:

http://www.dsprelated.com/dspbooks/pasp/Freeverb.html.

What do the numbers inside the boxes represent?

For example the first Comb has this information from which it runs: .21, .2,
1557

Best,

Doug



2008/12/1 Iain McCurdy :
> A digital reverb, in the mould of Schroeder or Moorer (google these
> names),
> can be designed using comb and all pass filters; Csound has plenty of
> these
> but if you want you can model comb and all pass filters using delay
> opcodes.
> The secret to creating a smooth reverb effect will be to choose
> appropriate
> values for delay (loop) time for the delays/filters - if you choose the
> wrong values you will either get discernible echoes or ringing sounds (or
> both). Have a look at the documention and example for the nreverb opcode
> as
> this will give you some clues as where to start.
> Bye, Iain
>
>> Date: Mon, 1 Dec 2008 03:09:07 -0800
>> From: basshead6949@hotmail.com
>> To: csound@lists.bath.ac.uk
>> Subject: [Csnd] Building my own reverb unit
>>
>>
>> Hi guys,
>>
>> It's been a while since I've been in the Csound loop but nevertheless I
>> now
>> have to use it to build my own reverb unit. I know that I have to
>> feedback
>> the same signal with a certain delay time and with slightly more
>> attenuation
>> each time for x amount of times. I was just on the look out for any good
>> advice from someone who has done this before.
>>
>> I am planning to use a vdelay to feed the signal back through and
>> attenuate
>> it. Now, considering what I ultimately want is a slider controlling
>> something comparable to room size and one for reflectivity, density and
>> maybe high/low cut (fairly simple) what would you suggest as being the
>> sensible opcodes and methods?
>>
>> I'm comparatively inexperienced so please, any suggestions will do.
>>
>> Thanks very much,
>>
>> Doug
>> --
>> View this message in context:
>> http://www.nabble.com/Building-my-own-reverb-unit-tp20769912p20769912.html
>> Sent from the Csound - General mailing list archive at Nabble.com.
>>
>>
>>
>> Send bugs reports to this list.
>> To unsubscribe, send email sympa@lists.bath.ac.uk with body "unsubscribe
>> csound"
>
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It's been years since I looked at this stuff, but I pulled up the Csound 
manual page on comb filters:

http://www.csounds.com/manual/html/comb.html

I'm guessing that two of those numbers are going to be reverb time and 
loop time.  The third might be a delay amount.  You'll have to 
experiment to figure out which numbers are what though.  :-)

The four digits numbers might be milliseconds, which would probably 
correlate to reverb time.

The one thing I do remember from building reverb units in Csound was 
that if you want to create smooth reverb, be sure to use loop and reverb 
times that are relatively prime.  This reduces/eliminates beating from 
the overlapping filters.

Good luck and have fun experimenting.

-peter





basshead6949 wrote:
> Hello,
> 
> Oeyvind, regarding this link's diagram of the parallel and series filters:
> 
> http://www.dsprelated.com/dspbooks/pasp/Freeverb.html.
> 
> What do the numbers inside the boxes represent?
> 
> For example the first Comb has this information from which it runs: .21, .2,
> 1557
> 
> Best,
> 
> Doug
> 
> 
> 
> 2008/12/1 Iain McCurdy :
>> A digital reverb, in the mould of Schroeder or Moorer (google these
>> names),
>> can be designed using comb and all pass filters; Csound has plenty of
>> these
>> but if you want you can model comb and all pass filters using delay
>> opcodes.
>> The secret to creating a smooth reverb effect will be to choose
>> appropriate
>> values for delay (loop) time for the delays/filters - if you choose the
>> wrong values you will either get discernible echoes or ringing sounds (or
>> both). Have a look at the documention and example for the nreverb opcode
>> as
>> this will give you some clues as where to start.
>> Bye, Iain
>>
>>> Date: Mon, 1 Dec 2008 03:09:07 -0800
>>> From: basshead6949@hotmail.com
>>> To: csound@lists.bath.ac.uk
>>> Subject: [Csnd] Building my own reverb unit
>>>
>>>
>>> Hi guys,
>>>
>>> It's been a while since I've been in the Csound loop but nevertheless I
>>> now
>>> have to use it to build my own reverb unit. I know that I have to
>>> feedback
>>> the same signal with a certain delay time and with slightly more
>>> attenuation
>>> each time for x amount of times. I was just on the look out for any good
>>> advice from someone who has done this before.
>>>
>>> I am planning to use a vdelay to feed the signal back through and
>>> attenuate
>>> it. Now, considering what I ultimately want is a slider controlling
>>> something comparable to room size and one for reflectivity, density and
>>> maybe high/low cut (fairly simple) what would you suggest as being the
>>> sensible opcodes and methods?
>>>
>>> I'm comparatively inexperienced so please, any suggestions will do.
>>>
>>> Thanks very much,
>>>
>>> Doug
>>> --
>>> View this message in context:
>>> http://www.nabble.com/Building-my-own-reverb-unit-tp20769912p20769912.html
>>> Sent from the Csound - General mailing list archive at Nabble.com.
>>>
>>>
>>>
>>> Send bugs reports to this list.
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>>> csound"
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