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  #201   Report Post  
Posted to rec.audio.tubes
Tynan AgviŠr Tynan AgviŠr is offline
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Posts: 19
Default Design for a small tube/valve mixer

John Byrns wrote in
:

In article ,
Ian Thompson-Bell wrote:

Ian Iveson wrote:
Ian wrote

The hump is indeed caused by that cap but it is made worse
by the fact that one end of the transformer is not
connected to ground but directly to that cap. I can see
the transformer zero would probably cancel it out in the
overall response and maybe that is what the designers
intended. However, the bass hump in the closed loop
response will still give rise to an unnecessary increase
in 1/f noise, so whilst a zero at the input fixes the
response it is treating the symptoms rather than curing
the disease.

Simulating with a 0.22uF series cap at the input removes
the hump.

Yes, but a cap won't get rid of the noise hump any more than
the transformer will.

A cap won't give you the 20dB gain that the transformer
will.

Why use a cap in series when you already have an inductor in
shunt? A cap is a bad idea IMO.


I know, I just put it there to check that the zero worked!

The noise hump is cut away by the output transformer.


Indeed, but if the hump was not there, the noise would be even
better. The hump is completely removed simply by connecting the lower
leg of the transformer to ground. To do that, and keep the first
stage bias the same you need to add a series cap to the input
transformer secondary.

Also, I am considering a variant of this for the RATMIXER mic pre and
as this would feed the mix bus there would be no need for a
transformer at this point in the circuit. Another reason for getting
rid of the hump and its added noise.


My version of the "RATMIXER" also uses a very similar microphone
amplifier circuit, however I don't understand your comment that "this
would feed the mix bus"? If the microphone amplifier feeds the mix
bus, where do you put the channel fader and pan pot, or is the point
simply that no transformer is needed?


Regards,

John Byrns


The piece below has served as the catalyst for the desire to acquire my
own mixer. All of my favorite recordings were produced with it. One of my
favorite engineers, Jan-Eric Persson, designed it in tandem with Kjell
Malmberg and has used it on virtually all Opus 3 Records releases(please
check the label's recordings out..simply stunning). Jan's recording
approach is simple, just mics(most of the time two, sometimes an extra
mic for double bass)mixertape machine. No EQ, Compression, or
anything of the sort. Just good mics, good amps, good venue, good
musicians. (for the record, *I am not posting this in hopes that yall
will come up with a copy of it for me*..just posting because I thought
you may find the pictures interesting)..so please, no comments like
"well, you said you wanted faders and those are rotaries"


http://farm3.static.flickr.com/2128/...c38eeb.jpg?v=0

http://farm3.static.flickr.com/2262/...2e720f.jpg?v=0

http://farm3.static.flickr.com/2187/...ffd675.jpg?v=0

The red knobs are bass-cut filter selectors for the 4 inputs and with
5 positions.
150 & 60Hz at 12dB/oct and 450, 225 & 75 Hz at 6dB/oct.
The yellow knobs are the input-level controls

The red one to the the far right is the Master output control.

The green one is the listening volume to the monitor amp.
The yellow button is before and after tape.

The actual meters are VU, plus that from -5dB and up to +5 there are peak
LED“s
The 0-level with the Telefunken M-28 is 514 nW/m.

Total max gain is 54 dB


it is not that heavy, and the power supply is a separate unit and that is
connected to the 8-pole flat pin connector on the right. (to avoid
hum).

-Tynan
  #202   Report Post  
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Ian Thompsson-Bell Ian Thompsson-Bell is offline
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Posts: 6
Default Design for a small tube/valve mixer

John Byrns wrote:

My version of the "RATMIXER" also uses a very similar microphone
amplifier circuit, however I don't understand your comment that "this
would feed the mix bus"? If the microphone amplifier feeds the mix bus,
where do you put the channel fader and pan pot, or is the point simply
that no transformer is needed?





I think there are two points here. First, the mic pre feeds the mix bus
(via the channel fader, pan and mute controls) so any 1/f noise from
unmuted channels reaches the mix bus.

Secondly, as the mix bus is unbalanced there is clearly no need for a
transformer at this point in the circuit.

Hope that is clearer.

Cheers

Ian
  #203   Report Post  
Posted to rec.audio.tubes
John Byrns John Byrns is offline
external usenet poster
 
Posts: 1,441
Default Design for a small tube/valve mixer

In article ,
"Tynan AgviŠr" wrote:

John Byrns wrote in
:

In article ,
Ian Thompson-Bell wrote:

Ian Iveson wrote:
Ian wrote

The hump is indeed caused by that cap but it is made worse
by the fact that one end of the transformer is not
connected to ground but directly to that cap. I can see
the transformer zero would probably cancel it out in the
overall response and maybe that is what the designers
intended. However, the bass hump in the closed loop
response will still give rise to an unnecessary increase
in 1/f noise, so whilst a zero at the input fixes the
response it is treating the symptoms rather than curing
the disease.

Simulating with a 0.22uF series cap at the input removes
the hump.

Yes, but a cap won't get rid of the noise hump any more than
the transformer will.

A cap won't give you the 20dB gain that the transformer
will.

Why use a cap in series when you already have an inductor in
shunt? A cap is a bad idea IMO.


I know, I just put it there to check that the zero worked!

The noise hump is cut away by the output transformer.


Indeed, but if the hump was not there, the noise would be even
better. The hump is completely removed simply by connecting the lower
leg of the transformer to ground. To do that, and keep the first
stage bias the same you need to add a series cap to the input
transformer secondary.

Also, I am considering a variant of this for the RATMIXER mic pre and
as this would feed the mix bus there would be no need for a
transformer at this point in the circuit. Another reason for getting
rid of the hump and its added noise.


My version of the "RATMIXER" also uses a very similar microphone
amplifier circuit, however I don't understand your comment that "this
would feed the mix bus"? If the microphone amplifier feeds the mix
bus, where do you put the channel fader and pan pot, or is the point
simply that no transformer is needed?


Regards,

John Byrns


The piece below has served as the catalyst for the desire to acquire my
own mixer. All of my favorite recordings were produced with it. One of my
favorite engineers, Jan-Eric Persson, designed it in tandem with Kjell
Malmberg and has used it on virtually all Opus 3 Records releases(please
check the label's recordings out..simply stunning). Jan's recording
approach is simple, just mics(most of the time two, sometimes an extra
mic for double bass)mixertape machine. No EQ, Compression, or
anything of the sort. Just good mics, good amps, good venue, good
musicians. (for the record, *I am not posting this in hopes that yall
will come up with a copy of it for me*..just posting because I thought
you may find the pictures interesting)..so please, no comments like
"well, you said you wanted faders and those are rotaries"

http://farm3.static.flickr.com/2128/...c38eeb.jpg?v=0

http://farm3.static.flickr.com/2262/...2e720f.jpg?v=0

http://farm3.static.flickr.com/2187/...ffd675.jpg?v=0

The red knobs are bass-cut filter selectors for the 4 inputs and with
5 positions.
150 & 60Hz at 12dB/oct and 450, 225 & 75 Hz at 6dB/oct.
The yellow knobs are the input-level controls

The red one to the the far right is the Master output control.

The green one is the listening volume to the monitor amp.
The yellow button is before and after tape.

The actual meters are VU, plus that from -5dB and up to +5 there are peak
LED“s
The 0-level with the Telefunken M-28 is 514 nW/m.

Total max gain is 54 dB

it is not that heavy, and the power supply is a separate unit and that is
connected to the 8-pole flat pin connector on the right. (to avoid
hum).


Hi Tynan,

I don't see the peak LED's in the photo of the front panel, were are
they located?

Does this mixer provide balanced outputs, from the interior photo I get
a gut feeling that it doesn't?

You asked for pan pots, this mixer doesn't appear to include them, it
isn't even obvious how the input channels are assigned to the two output
tracks, do you know how that is accomplished with this mixer, there
don't seem to be enough knobs/switches?

Since you seem to like this mixer, why don't you simply commission
someone to build a duplicate?


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
  #204   Report Post  
Posted to rec.audio.tubes
Tynan AgviŠr Tynan AgviŠr is offline
external usenet poster
 
Posts: 19
Default Design for a small tube/valve mixer

John Byrns wrote in
:

In article ,
"Tynan AgviŠr" wrote:

John Byrns wrote in
:

In article ,
Ian Thompson-Bell wrote:

Ian Iveson wrote:
Ian wrote

The hump is indeed caused by that cap but it is made worse
by the fact that one end of the transformer is not
connected to ground but directly to that cap. I can see
the transformer zero would probably cancel it out in the
overall response and maybe that is what the designers
intended. However, the bass hump in the closed loop
response will still give rise to an unnecessary increase
in 1/f noise, so whilst a zero at the input fixes the
response it is treating the symptoms rather than curing
the disease.

Simulating with a 0.22uF series cap at the input removes
the hump.

Yes, but a cap won't get rid of the noise hump any more than
the transformer will.

A cap won't give you the 20dB gain that the transformer
will.

Why use a cap in series when you already have an inductor in
shunt? A cap is a bad idea IMO.


I know, I just put it there to check that the zero worked!

The noise hump is cut away by the output transformer.


Indeed, but if the hump was not there, the noise would be even
better. The hump is completely removed simply by connecting the
lower leg of the transformer to ground. To do that, and keep the
first stage bias the same you need to add a series cap to the
input transformer secondary.

Also, I am considering a variant of this for the RATMIXER mic pre
and as this would feed the mix bus there would be no need for a
transformer at this point in the circuit. Another reason for
getting rid of the hump and its added noise.

My version of the "RATMIXER" also uses a very similar microphone
amplifier circuit, however I don't understand your comment that
"this would feed the mix bus"? If the microphone amplifier feeds
the mix bus, where do you put the channel fader and pan pot, or is
the point simply that no transformer is needed?


Regards,

John Byrns


The piece below has served as the catalyst for the desire to acquire
my own mixer. All of my favorite recordings were produced with it.
One of my favorite engineers, Jan-Eric Persson, designed it in tandem
with Kjell Malmberg and has used it on virtually all Opus 3 Records
releases(please check the label's recordings out..simply stunning).
Jan's recording approach is simple, just mics(most of the time two,
sometimes an extra mic for double bass)mixertape machine. No EQ,
Compression, or anything of the sort. Just good mics, good amps, good
venue, good musicians. (for the record, *I am not posting this in
hopes that yall will come up with a copy of it for me*..just posting
because I thought you may find the pictures interesting)..so please,
no comments like "well, you said you wanted faders and those are
rotaries"

http://farm3.static.flickr.com/2128/...c38eeb.jpg?v=0

http://farm3.static.flickr.com/2262/...2e720f.jpg?v=0

http://farm3.static.flickr.com/2187/...ffd675.jpg?v=0

The red knobs are bass-cut filter selectors for the 4 inputs and with
5 positions.
150 & 60Hz at 12dB/oct and 450, 225 & 75 Hz at 6dB/oct.
The yellow knobs are the input-level controls

The red one to the the far right is the Master output control.

The green one is the listening volume to the monitor amp.
The yellow button is before and after tape.

The actual meters are VU, plus that from -5dB and up to +5 there are
peak LED“s
The 0-level with the Telefunken M-28 is 514 nW/m.

Total max gain is 54 dB

it is not that heavy, and the power supply is a separate unit and
that is connected to the 8-pole flat pin connector on the right. (to
avoid hum).


Hi Tynan,

I don't see the peak LED's in the photo of the front panel, were are
they located?

Does this mixer provide balanced outputs, from the interior photo I
get a gut feeling that it doesn't?

You asked for pan pots, this mixer doesn't appear to include them, it
isn't even obvious how the input channels are assigned to the two
output tracks, do you know how that is accomplished with this mixer,
there don't seem to be enough knobs/switches?

Since you seem to like this mixer, why don't you simply commission
someone to build a duplicate?


Regards,

John Byrns

I have to ask about the LEDs..
John, as I stated many times(with this picture and others) , I was NOT
posting the picture with any intent to get a duplicate!!I just thought it
may be interesting I like the sound of the mixer, and the engineer that
uses it is genius...but I didnt want a carbon copy. Please dont take my
posting pictures as an attempt to get copies..it was just an FYI(and you
have done this twice, asked "well you said you wanted this and that, but
the PICTURE doesnt have it , yadda yadda") no, it does not provide
balanced outputs..it was going to a tape machine. the panning was hard
left, right, and center on that unit..it was fixed. again..I want a nice
sounding tube mixer, but I dont want a copy of what has been done
before..otherwise I would have contacted those guys...I want a design
from the folks here...hence my posting here and nowhere else!

John please read what I wrote in parentheses in the post above(announcing
the mixer). If I cant post pictures without folks taking them literally,
maybe I shouldnt post em..they are just FYI, maybe thought someone could
get ideas from the pictures..but Lord...again...I do NOT want copies!



  #205   Report Post  
Posted to rec.audio.tubes
John Byrns John Byrns is offline
external usenet poster
 
Posts: 1,441
Default Design for a small tube/valve mixer

In article ,
"Tynan AgviŠr" wrote:

John Byrns wrote in
:

In article ,
"Tynan AgviŠr" wrote:

The piece below has served as the catalyst for the desire to acquire
my own mixer. All of my favorite recordings were produced with it.
One of my favorite engineers, Jan-Eric Persson, designed it in tandem
with Kjell Malmberg and has used it on virtually all Opus 3 Records
releases(please check the label's recordings out..simply stunning).
Jan's recording approach is simple, just mics(most of the time two,
sometimes an extra mic for double bass)mixertape machine. No EQ,
Compression, or anything of the sort. Just good mics, good amps, good
venue, good musicians. (for the record, *I am not posting this in
hopes that yall will come up with a copy of it for me*..just posting
because I thought you may find the pictures interesting)..so please,
no comments like "well, you said you wanted faders and those are
rotaries"

http://farm3.static.flickr.com/2128/...c38eeb.jpg?v=0

http://farm3.static.flickr.com/2262/...2e720f.jpg?v=0

http://farm3.static.flickr.com/2187/...ffd675.jpg?v=0

The red knobs are bass-cut filter selectors for the 4 inputs and with
5 positions.
150 & 60Hz at 12dB/oct and 450, 225 & 75 Hz at 6dB/oct.
The yellow knobs are the input-level controls

The red one to the the far right is the Master output control.

The green one is the listening volume to the monitor amp.
The yellow button is before and after tape.

The actual meters are VU, plus that from -5dB and up to +5 there are
peak LED“s
The 0-level with the Telefunken M-28 is 514 nW/m.

Total max gain is 54 dB

it is not that heavy, and the power supply is a separate unit and
that is connected to the 8-pole flat pin connector on the right. (to
avoid hum).


Hi Tynan,

I don't see the peak LED's in the photo of the front panel, were are
they located?

Does this mixer provide balanced outputs, from the interior photo I
get a gut feeling that it doesn't?

You asked for pan pots, this mixer doesn't appear to include them, it
isn't even obvious how the input channels are assigned to the two
output tracks, do you know how that is accomplished with this mixer,
there don't seem to be enough knobs/switches?

Since you seem to like this mixer, why don't you simply commission
someone to build a duplicate?


I have to ask about the LEDs..
John, as I stated many times(with this picture and others) , I was NOT
posting the picture with any intent to get a duplicate!!I just thought it
may be interesting I like the sound of the mixer, and the engineer that
uses it is genius...but I didnt want a carbon copy. Please dont take my
posting pictures as an attempt to get copies..it was just an FYI(and you
have done this twice, asked "well you said you wanted this and that, but
the PICTURE doesnt have it , yadda yadda") no, it does not provide
balanced outputs..it was going to a tape machine. the panning was hard
left, right, and center on that unit..it was fixed. again..I want a nice
sounding tube mixer, but I dont want a copy of what has been done
before..otherwise I would have contacted those guys...I want a design
from the folks here...hence my posting here and nowhere else!

John please read what I wrote in parentheses in the post above(announcing
the mixer). If I cant post pictures without folks taking them literally,
maybe I shouldnt post em..they are just FYI, maybe thought someone could
get ideas from the pictures..but Lord...again...I do NOT want copies!


Sorry about the redundant questions, it is hard to keep track of your
requirements since they are not consolidated in a single place due to
the piecemeal way they have been presented. I will try to avoid future
questions about your requirements and just set my ship to sail its own
course.

With respect to your comment in parentheses, from the beginning I
completely missed your desire to have a custom one of a kind mixer, I
had assumed that if there was an already existing design that meet all
your desires/requirements, simply having a duplicate constructed would
be a viable alternative. I now understand that one of your prime
requirements is that your mixer be one of a kind.

Have you had any luck yet in locating someone willing to design and
construct a custom mixer for you? I am curious what the result might
look like, figuratively speaking.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
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