Why not just make FIRs by hand?

On Monday, August 22, 2016 at 2:40:40 PM UTC-4, Greg Berchin wrote:
> On Monday, August 22, 2016 at 12:51:56 PM UTC-5, radam...@gmail.com wrote:
> 
> > I'm moving to Vermont and starting an audio company that uses "hand-made FIR filters" with each tap individually crafted by RBJ
> 
> I tried that ... well, 2/3 of that - moving to Vermont and starting an audio company that uses hand-made FIR filters. Didn't make any money but did spend a fair amount of time hiking mountain trails with RB-J.

:-)

Mount Abraham, if i recall.

(and part way up Camels Hump.)

:-)

On 8/22/2016 7:18 PM, robert bristow-johnson wrote:
> On Monday, August 22, 2016 at 6:58:47 PM UTC-4, rickman wrote:
>> On 8/22/2016 2:40 PM, Greg Berchin wrote:
>>> On Monday, August 22, 2016 at 12:51:56 PM UTC-5, radam...@gmail.com wrote:
>>>
>>>> I'm moving to Vermont and starting an audio company that uses "hand-made FIR filters" with each tap individually crafted by RBJ
>>>
>>> I tried that ... well, 2/3 of that - moving to Vermont and starting an audio company that uses hand-made FIR filters. Didn't make any money but did spend a fair amount of time hiking mountain trails with RB-J.
>>
>> Do hand made FIR filters make a difference in the sound of audio gear?
>> Do you have to implement the filters with vacuum tubes to get just the
>> right tonal "feel"?
>>
>
> ones that use vacuum tubes as the tap elements (and making a CCD delay line outa tubes) have a nice warm sound that is particularly well suited for audio.  you might be able to do a nice convolutional reverb with, maybe, 100,000 vacuum tube triodes (12AX7 has two triodes per tube).
>
> i am waiting for someone like Bob to design a DSP targeted for audio outa tubes.  every gate, every flip-flop made outa 1940's technology.  that should have a wonderful warm analog sound.
>
> why shouldn't a company named Analog Devices do such?

How about analog signal processing?  Tubes might actually work for that. 
  FIR filters are just delays and adds...

-- 

Rick C

I think rickman  <gnuarm@gmail.com> wrote:

> ones that use vacuum tubes as the tap elements (and making a CCD delay
> line outa tubes) have a nice warm sound that is particularly well suited
> for audio.  you might be able to do a nice convolutional reverb with,
> maybe, 100,000 vacuum tube triodes (12AX7 has two triodes per tube).

Heresy.  Use 12AU7's, otherwise the assymmetry might be audible.

Steve

On Wednesday, August 17, 2016 at 1:25:47 AM UTC-7, mavavilj wrote:

(snip)
> So why doesn't one then create all such FIRs applied by the overlap-add
> FFT technique by this way, rather than using some of the more technical
> methods?

Seems that most technology is initially hand designed, then, as technology
improves, it is more and more automated.

Remember when PC boards were designed with black tape on mylar sheets?

Then ICs were designed the same way?

Before that, when airplanes were designed and built by hand?

It was not so long ago, the that Boeing 777 was designed, the first to be 
pretty much all designed using CAD.  When the designers first saw the
actual plane, one of the first things said was "Oh, so that's how big it is!"
(After looking at in on computer screens for years.)

In recent discussion about bringing manufacturing jobs back from overseas,
it seems that with automation, it can be cost effective to do many things with
robots in the US that were done by hand in other countries.  But it doesn't
mean so many jobs, mostly watching over the robots. 

In the simplest cases, I suppose digital filters can still be hand designed.

-- glen

On Monday, August 22, 2016 at 6:18:26 PM UTC-5, robert bristow-johnson wrote:

> i am waiting for someone like Bob to design a DSP targeted for audio outa tubes.  every gate, every flip-flop made outa 1940's technology.  that should have a wonderful warm analog sound.

For many years I ran an all-digital system through a DSP crossover that fed high frequencies to a conrad-johnson MV-50 amp (EL34 tubes) and low frequencies to a Threshold S/200 amp (transistors). It was quite a happy combination.

I have designed similar systems for friends with tubes and horn-loaded loudspeakers. They were very satisfying combinations of high-tech and low-tech. The only better example of high-tech low-tech that I know of is the titanium crowbar that I obtained a while back.

On Monday, August 22, 2016 at 6:26:58 PM UTC-5, rickman wrote:

> How about analog signal processing?  Tubes might actually work for that. 
>   FIR filters are just delays and adds...

http://pubs.acs.org/doi/abs/10.1021/ac50008a049?journalCode=ancham

On Monday, August 22, 2016 at 7:33:31 PM UTC-4, Steve Pope wrote:
> I think rickman  <gnuarm@gmail.com> wrote:
> 
> > ones that use vacuum tubes as the tap elements (and making a CCD delay
> > line outa tubes) have a nice warm sound that is particularly well suited
> > for audio.  you might be able to do a nice convolutional reverb with,
> > maybe, 100,000 vacuum tube triodes (12AX7 has two triodes per tube).
> 
> Heresy.  Use 12AU7's, otherwise the assymmetry might be audible.
> 

when i was a kid, i had an old Knight-Kit breadboarding product that had a 12AU7 in it.  don't remember the name of that product.  this was in the 60s.  didn't need as high plate voltage that the 12AX7 needed.

robert bristow-johnson  <rbj@audioimagination.com> wrote:

>On Monday, August 22, 2016 at 7:33:31 PM UTC-4, Steve Pope wrote:

>> I think rickman  <gnuarm@gmail.com> wrote:
>> 
>> > ones that use vacuum tubes as the tap elements (and making a CCD delay
>> > line outa tubes) have a nice warm sound that is particularly well suited
>> > for audio.  you might be able to do a nice convolutional reverb with,
>> > maybe, 100,000 vacuum tube triodes (12AX7 has two triodes per tube).
>> 
>> Heresy.  Use 12AU7's, otherwise the assymmetry might be audible.
>> 

>when i was a kid, i had an old Knight-Kit breadboarding product that had
>a 12AU7 in it.  don't remember the name of that product.  this was in
>the 60s.  didn't need as high plate voltage that the 12AX7 needed.

That may be, what I am recollecting is that the X7 had two
different triodes, one with higher gain, whereas the U7
had a balanced pair of triodes.  Much more _simpatico_ .

S.

On 8/23/2016 2:38 AM, Steve Pope wrote:
> robert bristow-johnson  <rbj@audioimagination.com> wrote:
>
>> On Monday, August 22, 2016 at 7:33:31 PM UTC-4, Steve Pope wrote:
>
>>> I think rickman  <gnuarm@gmail.com> wrote:
>>>
>>>> ones that use vacuum tubes as the tap elements (and making a CCD delay
>>>> line outa tubes) have a nice warm sound that is particularly well suited
>>>> for audio.  you might be able to do a nice convolutional reverb with,
>>>> maybe, 100,000 vacuum tube triodes (12AX7 has two triodes per tube).
>>>
>>> Heresy.  Use 12AU7's, otherwise the assymmetry might be audible.
>>>
>
>> when i was a kid, i had an old Knight-Kit breadboarding product that had
>> a 12AU7 in it.  don't remember the name of that product.  this was in
>> the 60s.  didn't need as high plate voltage that the 12AX7 needed.
>
> That may be, what I am recollecting is that the X7 had two
> different triodes, one with higher gain, whereas the U7
> had a balanced pair of triodes.  Much more _simpatico_ .

I don't recall that.  I think both sections were equivalent in the 12AX7.

-- 

Rick C

On Tuesday, August 23, 2016 at 12:22:23 AM UTC-7, rickman wrote:
> On 8/23/2016 2:38 AM, Steve Pope wrote:

(snip)
> > That may be, what I am recollecting is that the X7 had two
> > different triodes, one with higher gain, whereas the U7
> > had a balanced pair of triodes.  Much more _simpatico_ .

> I don't recall that.  I think both sections were equivalent in the 12AX7.

http://www.mif.pg.gda.pl/homepages/frank/sheets/137/1/12AX7.pdf

Seems that some capacitance is slightly different, but I don't see
anything else different.  The capacitance might be from electrode and
pin position differences.