Garrett wrote:

You could probably find a suitable Bud box for it. I do agree the
pricing is something to consider still.

On 2004-11-12 17:37:14 -0800, (Mike Rivers) said:
I think that the average DIYer today would find that to be too much
cash to put into a project, particularly since it involves a case and
considerable metalworking skill to make a unit that looks decent. You
might sell about ten, and you know what Recording pays for articles.
g

I think people think they want to build a great preamp project that
costs less in total per channel than the price of a jensen input
transformer. g

--
ha

"agent86" wrote in message
.. .

What's street on the 8 channel Presonus these days? The Full Compass
catalog copy says "Jensen", but IIRC, they had switched to a cheaper
transformer sometime back.

I assume you mean the M80, since the other Presonus 8-channel units don't
have transformers. The M80 can be had new for around $1400.

Hal Laurent
Baltimore

"agent86" wrote in message
.. .

What's street on the 8 channel Presonus these days? The Full Compass
catalog copy says "Jensen", but IIRC, they had switched to a cheaper
transformer sometime back.

I assume you mean the M80, since the other Presonus 8-channel units don't
have transformers. The M80 can be had new for around $1400.

Hal Laurent
Baltimore

"Paul Stamler" wrote in message
...

This project doesn't aim at the stars. If you want the stars in a neutral
sort of way, I say buy a rack full of Great River preamps. They're
superb-sounding, and you get a warranty from a well-established company.
This project has a different ambition; I'd put the quality one notch below
Great River (which is still damned good -- I've made some very nice
recordings using this circuit). The tradeoff is convenience (2RU for 8
channels rather than 8) and cost. Like I say, it's a niche.

You don't need 8RU for 8 channels of Great River (or Hardy). A pair
of the four-channel versions of either will fit in 2RU. As will 8 channels
of Sytek.

Hal Laurent
Baltimore

"Paul Stamler" wrote in message
...

This project doesn't aim at the stars. If you want the stars in a neutral
sort of way, I say buy a rack full of Great River preamps. They're
superb-sounding, and you get a warranty from a well-established company.
This project has a different ambition; I'd put the quality one notch below
Great River (which is still damned good -- I've made some very nice
recordings using this circuit). The tradeoff is convenience (2RU for 8
channels rather than 8) and cost. Like I say, it's a niche.

You don't need 8RU for 8 channels of Great River (or Hardy). A pair
of the four-channel versions of either will fit in 2RU. As will 8 channels
of Sytek.

Hal Laurent
Baltimore

Paul Stamler wrote:

Revised cost estimate:

2 ch.: $490
4 ch.: $840
8 ch.: $1540

The idea is to provide up to 8 channels of preamp in a 2U box (plus the
outboard power supply). 8 in a box for compactness, particularly for
people doing remote work, or for folks who just want 8 identical
good-quality preamps. It seems to be a pretty popular format at several
price points; the one thing I notice, though, is that none of the
8-bangers out there are transformer-coupled, and some of us like
transformers, for (as I mentioned) RFI-proofing, loading, whatever. So I'm
looking to see whether there's a niche here. There wouldn't be, I don't
think, for a manufactured version of this; the price would be prohibitive.
But perhaps as a DIY it might slip in. So I'm running it up the flagpole.

What's street on the 8 channel Presonus these days? The Full Compass
catalog copy says "Jensen", but IIRC, they had switched to a cheaper
transformer sometime back.

I'm one of those who likes transformers too. But I've come to the
conclusion that the most cost effective avenue (for me) is to save up for a
GR or a Hardy (since I am determined to get one eventually anyway).
Obviously, everybody's situation is different. But I kind of think most
people would sooner buy a complete functional unit than build it IF what
they need is available at anywhere close to the same cost.

But good luck with it anyway.

Paul Stamler wrote:

Revised cost estimate:

2 ch.: $490
4 ch.: $840
8 ch.: $1540

The idea is to provide up to 8 channels of preamp in a 2U box (plus the
outboard power supply). 8 in a box for compactness, particularly for
people doing remote work, or for folks who just want 8 identical
good-quality preamps. It seems to be a pretty popular format at several
price points; the one thing I notice, though, is that none of the
8-bangers out there are transformer-coupled, and some of us like
transformers, for (as I mentioned) RFI-proofing, loading, whatever. So I'm
looking to see whether there's a niche here. There wouldn't be, I don't
think, for a manufactured version of this; the price would be prohibitive.
But perhaps as a DIY it might slip in. So I'm running it up the flagpole.

What's street on the 8 channel Presonus these days? The Full Compass
catalog copy says "Jensen", but IIRC, they had switched to a cheaper
transformer sometime back.

I'm one of those who likes transformers too. But I've come to the
conclusion that the most cost effective avenue (for me) is to save up for a
GR or a Hardy (since I am determined to get one eventually anyway).
Obviously, everybody's situation is different. But I kind of think most
people would sooner buy a complete functional unit than build it IF what
they need is available at anywhere close to the same cost.

But good luck with it anyway.

On 2004-11-13, Mike Rivers wrote:

If you're going to build something that costs $2,000 or more, you want
to put it in a box that makes it look like $2,000, with all the round
holes round, and lined up straight. And you probably want engraved or
silkscreened legends rather than strips of label tape.

A nice front panel is easy! You don't have to have a CNC mill yourself,
and you don't have to struggle with the dremel. Check out Front Panel
Express, or Schaeffer AG. The cost depends on the complexity of your
panel, but it is quite reasonable, and cheap enough to be used on
countless low budget DIY synth projects that I've seen.

On 2004-11-13, Mike Rivers wrote:

If you're going to build something that costs $2,000 or more, you want
to put it in a box that makes it look like $2,000, with all the round
holes round, and lined up straight. And you probably want engraved or
silkscreened legends rather than strips of label tape.

A nice front panel is easy! You don't have to have a CNC mill yourself,
and you don't have to struggle with the dremel. Check out Front Panel
Express, or Schaeffer AG. The cost depends on the complexity of your
panel, but it is quite reasonable, and cheap enough to be used on
countless low budget DIY synth projects that I've seen.

Personally, I wouldn't mind what it looked like as long as it sounded
good and the 1500 or 1800 I spent was justified. I think the purpose
for me would be just usability. No bling or whatever.

cheers

garrett


On 2004-11-13 08:11:13 -0800, (Mike Rivers) said:


If you're going to build something that costs $2,000 or more, you want
to put it in a box that makes it look like $2,000, with all the round
holes round, and lined up straight. And you probably want engraved or
silkscreened legends rather than strips of label tape. One of the
things about undertaking a DIY project (and our furniture-building
friends will surely agree) is not just to make something cheap or to
make something that you can't buy easily, but to make something that
you're proud of - whether it's a mic preamp, a custom cable, or a set
of shelves to store your backups.

There are a couple of companies that advertise in the trade magazines
that custom-punched engraved panels but that's still pretty expensive.
Markertek is one. Hammond makes a nice rack-mount case for
construction projects. A 2-space one runs between $55 and $90
depending on depth and venting.

Power supplies are probably best bought given the difficulty with
finding suitable transformers. That would be in the $100-150 range for
bi-polar 15 to 24 volts plus a single 48 volt supply. You'd need a
chassis or case for those, too.

Personally, I wouldn't mind what it looked like as long as it sounded
good and the 1500 or 1800 I spent was justified. I think the purpose
for me would be just usability. No bling or whatever.

cheers

garrett


On 2004-11-13 08:11:13 -0800, (Mike Rivers) said:


If you're going to build something that costs $2,000 or more, you want
to put it in a box that makes it look like $2,000, with all the round
holes round, and lined up straight. And you probably want engraved or
silkscreened legends rather than strips of label tape. One of the
things about undertaking a DIY project (and our furniture-building
friends will surely agree) is not just to make something cheap or to
make something that you can't buy easily, but to make something that
you're proud of - whether it's a mic preamp, a custom cable, or a set
of shelves to store your backups.

There are a couple of companies that advertise in the trade magazines
that custom-punched engraved panels but that's still pretty expensive.
Markertek is one. Hammond makes a nice rack-mount case for
construction projects. A 2-space one runs between $55 and $90
depending on depth and venting.

Power supplies are probably best bought given the difficulty with
finding suitable transformers. That would be in the $100-150 range for
bi-polar 15 to 24 volts plus a single 48 volt supply. You'd need a
chassis or case for those, too.

Paul Stamler wrote:

You sure aren't. I'd love to be able to spec something exactly that way. So
far, though, I haven't found *any* dealer that has everything. If I could, I
would specify them that way in a microsecond.

I try very hard to build projects so as much as possible can be ordered
from one supplier, almost always Digi-Key. Sometimes this means reducing
some aspect of performance by replacing a difficult part with one that
Digi-Key has stocked.

The Chinese mike modification article sat on the shelf for about three years
before getting published, because I couldn't find a decent supplier for high
value resistors in small quantities. As soon as Digi-Key picked up the
Ohmite line, the article went into print.

The long-awaited tube mike preamp article that I promised Nick Batzdorf
back when he was editing Recording has still not come out yet, and finding
a single parts source is half of the problem there. I have it down to six
suppliers but that's way too many.

One I'd like to see, and don't have the requisite knowledge to design, would
be a really good word clock generator for a couple of hundred bucks. Scott,
are you lisening?

I don't have any way of measuring how accurate a clock is any longer. They
shut down some of the labs at my day job and I no longer have the Tek
modulation domain analyzer to play with. This makes it very difficult to
build a reference clock and really assure yourself that it's any good.
I can build a clock, sure. But will it be an improvement? I have no way of
telling.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Paul Stamler wrote:

You sure aren't. I'd love to be able to spec something exactly that way. So
far, though, I haven't found *any* dealer that has everything. If I could, I
would specify them that way in a microsecond.

I try very hard to build projects so as much as possible can be ordered
from one supplier, almost always Digi-Key. Sometimes this means reducing
some aspect of performance by replacing a difficult part with one that
Digi-Key has stocked.

The Chinese mike modification article sat on the shelf for about three years
before getting published, because I couldn't find a decent supplier for high
value resistors in small quantities. As soon as Digi-Key picked up the
Ohmite line, the article went into print.

The long-awaited tube mike preamp article that I promised Nick Batzdorf
back when he was editing Recording has still not come out yet, and finding
a single parts source is half of the problem there. I have it down to six
suppliers but that's way too many.

One I'd like to see, and don't have the requisite knowledge to design, would
be a really good word clock generator for a couple of hundred bucks. Scott,
are you lisening?

I don't have any way of measuring how accurate a clock is any longer. They
shut down some of the labs at my day job and I no longer have the Tek
modulation domain analyzer to play with. This makes it very difficult to
build a reference clock and really assure yourself that it's any good.
I can build a clock, sure. But will it be an improvement? I have no way of
telling.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

....

and I'd make sure the design was RFI proof for the input and output as
well as the power supply.

I think RFI suseptability is one of the biggest weakness of commercial
gear.

If you create a bullet proof design RFI wse, it would have appeal.

That means ground the XLR connector shield pin and shell DIRECTLY to
the metal chassis for starters.


Mark

....

and I'd make sure the design was RFI proof for the input and output as
well as the power supply.

I think RFI suseptability is one of the biggest weakness of commercial
gear.

If you create a bullet proof design RFI wse, it would have appeal.

That means ground the XLR connector shield pin and shell DIRECTLY to
the metal chassis for starters.


Mark

Mark wrote:

...

and I'd make sure the design was RFI proof for the input and output as
well as the power supply.

I think RFI suseptability is one of the biggest weakness of commercial
gear.

If you create a bullet proof design RFI wse, it would have appeal.

That means ground the XLR connector shield pin and shell DIRECTLY to
the metal chassis for starters.

Does anyone *not* do that these days ?

Just asking. Been there done that - had the EMI course ( as part of his
consultancy ) over the years from a wonderful Hungarian ? expert.

He thinks the EMI regs are bonkers ( as in totally over the top ) btw !


Graham

Mark wrote:

...

and I'd make sure the design was RFI proof for the input and output as
well as the power supply.

I think RFI suseptability is one of the biggest weakness of commercial
gear.

If you create a bullet proof design RFI wse, it would have appeal.

That means ground the XLR connector shield pin and shell DIRECTLY to
the metal chassis for starters.

Does anyone *not* do that these days ?

Just asking. Been there done that - had the EMI course ( as part of his
consultancy ) over the years from a wonderful Hungarian ? expert.

He thinks the EMI regs are bonkers ( as in totally over the top ) btw !


Graham

normanstrong wrote:

If you want
to design something useful, come up with a battery operated unit at
$50/channel.

My sentiment as well. No rolloff necessasary, 60 dB gain,
-130 dBu A weighted Ein noise, phantom power.

What I'm dying for is a four channel as per above but with a
form of gain control that will allow any number of channels
to be ganged and operated with a single control. Some kind
precision voltage controled pot on each channel if such a
thing exists.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

normanstrong wrote:

If you want
to design something useful, come up with a battery operated unit at
$50/channel.

My sentiment as well. No rolloff necessasary, 60 dB gain,
-130 dBu A weighted Ein noise, phantom power.

What I'm dying for is a four channel as per above but with a
form of gain control that will allow any number of channels
to be ganged and operated with a single control. Some kind
precision voltage controled pot on each channel if such a
thing exists.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

On 13 Nov 2004 17:06:49 -0500, (Scott Dorsey) wrote:


The long-awaited tube mike preamp article that I promised Nick Batzdorf
back when he was editing Recording has still not come out yet, and finding
a single parts source is half of the problem there. I have it down to six
suppliers but that's way too many.

Would that be the transformerless input :-)


Frank /~ http://newmex.com/f10
@/

On 13 Nov 2004 17:06:49 -0500, (Scott Dorsey) wrote:


The long-awaited tube mike preamp article that I promised Nick Batzdorf
back when he was editing Recording has still not come out yet, and finding
a single parts source is half of the problem there. I have it down to six
suppliers but that's way too many.

Would that be the transformerless input :-)


Frank /~ http://newmex.com/f10
@/

In article writes:

I have some general opinions on magazine-published DIY projects, and
this is aimed not only at Mr Stamler but also Mr Dorsey and everyone
else that do these things.

First, I want to be able to get ALL parts at once from one place, and
that must include the chassis.

That's really nice, but unless someone is willing to put together a
complete kit, it really can't be done. Paia used to do this but they
don't seem to be quite so active in that area these days. Understand
that this requires a substantial investment when it comes to
metalwork. They can often use resistors, capacitors and op amp chips
for multiple products but they can't punch a chassis for an 8-channel
mic preamp and use it for a compressor.

In case you didn't know this, most
people don't have the tools to drill in metal when it comes to the
diameters needed for XLR connectors.

Actually that isn't too difficult. If you're going to build a $2,000
preamp, you're probably into building things and you don't have to
start out by buying every tool that you need, because you already have
a decent shop. A good start for audio projects is a set of Greenlee
chassis punches for male and female XLR connectors, about $40 a piece.
I'll admit that this can make a single channel project a bit
expensive, but DIY projects are addictive. If you do one, you'll
probably do several.

But I understand completely where you're coming from. When I was in
high school I worked summers and Saturdays in the tool crib of a
machine shop and I built some lovely ham radio gear because I had
access to brakes and punches for making the chassis. It made a big
difference in projects that I started over having to use a ready-made
chassis that was too big, too small, too deep, or too shallow, and had
to make holes for tube sockets by drilling a bunch of holes around the
circumference of a circle and filing out the scrap. Today I have a
drill press but no brake, so I don't do as much DIY as I used to.

I want to whip out my credit card, order one neat package with
EVERYTHING in it and sit down a couple of hours every sunday to
assemble.

Too bad you're too young to have ever built a Heathkit. But they went
out of business because eventually it wasn't cost effective to put
together and document a kit. You could buy the equivalent a whole lot
cheaper. A technician who used to work with me built a Heathkit color
TV and a Heathkit microwave oven, and had Heathkit oscilloscopes and
signal generators in his home TV service shop. In 1965 you could save
money by building the kit, but today you can buy better commercial
products for a fraction of the cost of the Heathkits, even in 1965
dollars.

Second, I don't think anyone is interested in merly "decent" or
"servicable" projects. I think most readers have too much of that
already. We want "really good" or even "outstanding".

This is why I didn't think Paul's project would be a smashing success.
On the other hand, a project like Scott's Oktava mic modifications
that involve a simple circuit board that he can provide, a handful of
parts, and only small hand tools are pretty popular.

To keep price down I think you need to make costly features optional.
Many people couldn't care less about HP-filtering, phase switches,
metering and balanced outputs in a preamp for instance.

I wrote an article in Recording a while back about developing your own
DIY project (using a monitor switcher as an example) in which I
explained exactly that concept - but the point of my article was that
YOU could make those decisions. It's not difficult to find application
notes for transfomrers and op amps that will get you a decent mic
preamp and you can make it "really good" or even "outstanding" by the
way you apply what's in those application notes. If you want someone
to make those decisions for you, you have to accept his take on what's
good for you.

Here are some DIY-projects that I would like to see (and if they have
already been published, please tell me which issue they are in):

-Parametric EQ for live use. A clean parametric EQ with very narrow
bands for full-program corrective live use.

Paia had a kit for one many years ago, and it's probalby still in
their catalog. I built one and I still use it occasionally.

-A/D and D/A converter. There is a remarkable black hole in the market
for stand-alone 2ch converters in the sub $1000 area. I'm sure there
are economical reasons for this but if a DIY project could fit in
there it would be wonderful.

This is one of those areas (like mic preamps - see John La Grou's
recent postings on the subject) where "art" comes into play. Again,
there are application notes for perfectly good A/D and D/A chips that
will get you the functions with reasonably good performance. But in
order to make it really great, you need a nice clean power supply, a
low jitter clock source, and good analog circuitry around the chip.
That's about four application notes. If you want someone to combine
those, experiment with optimizing components and circuit board layout,
finding sources for all the parts, and punching a chassis, who's going
to pay for it?

-A "Re-amping" capable DI box. In fact, it wouldn't have to be able to
do normal DI at all.

This is a perfectly good example of a project that you could develop
yourself. All you need to do is understand what you need to
accomplish. Package it as pretty or as ugly as you wish.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

In article writes:

I have some general opinions on magazine-published DIY projects, and
this is aimed not only at Mr Stamler but also Mr Dorsey and everyone
else that do these things.

First, I want to be able to get ALL parts at once from one place, and
that must include the chassis.

That's really nice, but unless someone is willing to put together a
complete kit, it really can't be done. Paia used to do this but they
don't seem to be quite so active in that area these days. Understand
that this requires a substantial investment when it comes to
metalwork. They can often use resistors, capacitors and op amp chips
for multiple products but they can't punch a chassis for an 8-channel
mic preamp and use it for a compressor.

In case you didn't know this, most
people don't have the tools to drill in metal when it comes to the
diameters needed for XLR connectors.

Actually that isn't too difficult. If you're going to build a $2,000
preamp, you're probably into building things and you don't have to
start out by buying every tool that you need, because you already have
a decent shop. A good start for audio projects is a set of Greenlee
chassis punches for male and female XLR connectors, about $40 a piece.
I'll admit that this can make a single channel project a bit
expensive, but DIY projects are addictive. If you do one, you'll
probably do several.

But I understand completely where you're coming from. When I was in
high school I worked summers and Saturdays in the tool crib of a
machine shop and I built some lovely ham radio gear because I had
access to brakes and punches for making the chassis. It made a big
difference in projects that I started over having to use a ready-made
chassis that was too big, too small, too deep, or too shallow, and had
to make holes for tube sockets by drilling a bunch of holes around the
circumference of a circle and filing out the scrap. Today I have a
drill press but no brake, so I don't do as much DIY as I used to.

I want to whip out my credit card, order one neat package with
EVERYTHING in it and sit down a couple of hours every sunday to
assemble.

Too bad you're too young to have ever built a Heathkit. But they went
out of business because eventually it wasn't cost effective to put
together and document a kit. You could buy the equivalent a whole lot
cheaper. A technician who used to work with me built a Heathkit color
TV and a Heathkit microwave oven, and had Heathkit oscilloscopes and
signal generators in his home TV service shop. In 1965 you could save
money by building the kit, but today you can buy better commercial
products for a fraction of the cost of the Heathkits, even in 1965
dollars.

Second, I don't think anyone is interested in merly "decent" or
"servicable" projects. I think most readers have too much of that
already. We want "really good" or even "outstanding".

This is why I didn't think Paul's project would be a smashing success.
On the other hand, a project like Scott's Oktava mic modifications
that involve a simple circuit board that he can provide, a handful of
parts, and only small hand tools are pretty popular.

To keep price down I think you need to make costly features optional.
Many people couldn't care less about HP-filtering, phase switches,
metering and balanced outputs in a preamp for instance.

I wrote an article in Recording a while back about developing your own
DIY project (using a monitor switcher as an example) in which I
explained exactly that concept - but the point of my article was that
YOU could make those decisions. It's not difficult to find application
notes for transfomrers and op amps that will get you a decent mic
preamp and you can make it "really good" or even "outstanding" by the
way you apply what's in those application notes. If you want someone
to make those decisions for you, you have to accept his take on what's
good for you.

Here are some DIY-projects that I would like to see (and if they have
already been published, please tell me which issue they are in):

-Parametric EQ for live use. A clean parametric EQ with very narrow
bands for full-program corrective live use.

Paia had a kit for one many years ago, and it's probalby still in
their catalog. I built one and I still use it occasionally.

-A/D and D/A converter. There is a remarkable black hole in the market
for stand-alone 2ch converters in the sub $1000 area. I'm sure there
are economical reasons for this but if a DIY project could fit in
there it would be wonderful.

This is one of those areas (like mic preamps - see John La Grou's
recent postings on the subject) where "art" comes into play. Again,
there are application notes for perfectly good A/D and D/A chips that
will get you the functions with reasonably good performance. But in
order to make it really great, you need a nice clean power supply, a
low jitter clock source, and good analog circuitry around the chip.
That's about four application notes. If you want someone to combine
those, experiment with optimizing components and circuit board layout,
finding sources for all the parts, and punching a chassis, who's going
to pay for it?

-A "Re-amping" capable DI box. In fact, it wouldn't have to be able to
do normal DI at all.

This is a perfectly good example of a project that you could develop
yourself. All you need to do is understand what you need to
accomplish. Package it as pretty or as ugly as you wish.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

Mark wrote:

and I'd make sure the design was RFI proof for the input and output as
well as the power supply.

With an input transformer, that's easy to do. High CMRR and low-pass
filtering are free in the bargain.

I think RFI suseptability is one of the biggest weakness of commercial
gear.

That's because people are willing to put up with bad design. It's not just
that transformers are expensive; just looking at the number of internal
ground loops on some commercial boxes out there is amazing.

If you create a bullet proof design RFI wse, it would have appeal.

That means ground the XLR connector shield pin and shell DIRECTLY to
the metal chassis for starters.

Not necessarily. Check out Deane Jensen's recent papers on the "Pin 1
Problem."
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Mark wrote:

and I'd make sure the design was RFI proof for the input and output as
well as the power supply.

With an input transformer, that's easy to do. High CMRR and low-pass
filtering are free in the bargain.

I think RFI suseptability is one of the biggest weakness of commercial
gear.

That's because people are willing to put up with bad design. It's not just
that transformers are expensive; just looking at the number of internal
ground loops on some commercial boxes out there is amazing.

If you create a bullet proof design RFI wse, it would have appeal.

That means ground the XLR connector shield pin and shell DIRECTLY to
the metal chassis for starters.

Not necessarily. Check out Deane Jensen's recent papers on the "Pin 1
Problem."
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Frank Vuotto wrote:
On 13 Nov 2004 17:06:49 -0500, (Scott Dorsey) wrote:

The long-awaited tube mike preamp article that I promised Nick Batzdorf
back when he was editing Recording has still not come out yet, and finding
a single parts source is half of the problem there. I have it down to six
suppliers but that's way too many.

Would that be the transformerless input :-)

Not at the price point Recording wants for DIY projects. If I could do a
transformerless one for cheap, that would eliminate one of the six suppliers
(which is Lundahl). I played around a little bit with a transformerless
grounded-grid design with a bunch of paralleled tubes, and it sounded good,
but it required a lot of trimming and selected tubes in order to get it
quiet and with low distortion. Actually winds up costing _more_ than a
transformer input, what with all the more expensive input tubes and the
trimpots.

About half of the cost of the preamp actually is in the power supply, and I
worked very hard to try and bring the power supply parts cost down and try
and do it entirely with Digi-Key parts. I was not able to do so. Everything
I did to cut corners in the supply wound up affecting the sound too much.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Frank Vuotto wrote:
On 13 Nov 2004 17:06:49 -0500, (Scott Dorsey) wrote:

The long-awaited tube mike preamp article that I promised Nick Batzdorf
back when he was editing Recording has still not come out yet, and finding
a single parts source is half of the problem there. I have it down to six
suppliers but that's way too many.

Would that be the transformerless input :-)

Not at the price point Recording wants for DIY projects. If I could do a
transformerless one for cheap, that would eliminate one of the six suppliers
(which is Lundahl). I played around a little bit with a transformerless
grounded-grid design with a bunch of paralleled tubes, and it sounded good,
but it required a lot of trimming and selected tubes in order to get it
quiet and with low distortion. Actually winds up costing _more_ than a
transformer input, what with all the more expensive input tubes and the
trimpots.

About half of the cost of the preamp actually is in the power supply, and I
worked very hard to try and bring the power supply parts cost down and try
and do it entirely with Digi-Key parts. I was not able to do so. Everything
I did to cut corners in the supply wound up affecting the sound too much.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Mike Rivers wrote:
In article writes:

In case you didn't know this, most
people don't have the tools to drill in metal when it comes to
the diameters needed for XLR connectors.


Actually that isn't too difficult. If you're going to build a $2,000
preamp, you're probably into building things and you don't have to
start out by buying every tool that you need, because you already have
a decent shop. A good start for audio projects is a set of Greenlee
chassis punches for male and female XLR connectors, about $40 a piece.

I thought these punches were more like $200-250 each? You are talking about the ones with the slots for the mounting screws, right?

Mike Rivers wrote:
In article writes:

In case you didn't know this, most
people don't have the tools to drill in metal when it comes to
the diameters needed for XLR connectors.


Actually that isn't too difficult. If you're going to build a $2,000
preamp, you're probably into building things and you don't have to
start out by buying every tool that you need, because you already have
a decent shop. A good start for audio projects is a set of Greenlee
chassis punches for male and female XLR connectors, about $40 a piece.

I thought these punches were more like $200-250 each? You are talking about the ones with the slots for the mounting screws, right?

"Paul Stamler" wrote in message newsk9ld.891630

Approximate costs are as follows. These include everything except the
cases,
which are up to you. At the moment I'm assuming the PC boards would cost
$25.00 / ea.;


Good so far ....

that's the biggest unknown in the equation. I can't really
fill that in until I design the boards, and I'm not gonna do that until I
find out whether anybody's interested. (Also, of course, price of the
boards
will vary depending on how many I order.) There are options which will
raise
the price, and some that will lower it, but this is the basic design.

Each input channel: $220.00

What is in it that bumps up the cost this much ? Maybe transformer, stepped
swtich, platinum op-amps ?


Power Supply: $120.00

I'm so would supply own transformer....

Any interest?

Yep, in the cct board !


geoff

"Paul Stamler" wrote in message newsk9ld.891630

Approximate costs are as follows. These include everything except the
cases,
which are up to you. At the moment I'm assuming the PC boards would cost
$25.00 / ea.;


Good so far ....

that's the biggest unknown in the equation. I can't really
fill that in until I design the boards, and I'm not gonna do that until I
find out whether anybody's interested. (Also, of course, price of the
boards
will vary depending on how many I order.) There are options which will
raise
the price, and some that will lower it, but this is the basic design.

Each input channel: $220.00

What is in it that bumps up the cost this much ? Maybe transformer, stepped
swtich, platinum op-amps ?


Power Supply: $120.00

I'm so would supply own transformer....

Any interest?

Yep, in the cct board !


geoff

"agent86" wrote in message
.. .
Mike Rivers wrote:

I think that the average DIYer today would find that to be too much
cash to put into a project, particularly since it involves a case and
considerable metalworking skill to make a unit that looks decent.

Very true. With the RNP going for $475 new, what's the point (unless you
just absolutely HAVE to have transformers). And why would you reall NEED
transformers at that price point, since Shure 57s behave themselves pretty
well with the RNP?


I'd be more interested in variable input impedence.

geoff

"agent86" wrote in message
.. .
Mike Rivers wrote:

I think that the average DIYer today would find that to be too much
cash to put into a project, particularly since it involves a case and
considerable metalworking skill to make a unit that looks decent.

Very true. With the RNP going for $475 new, what's the point (unless you
just absolutely HAVE to have transformers). And why would you reall NEED
transformers at that price point, since Shure 57s behave themselves pretty
well with the RNP?


I'd be more interested in variable input impedence.

geoff

On Fri, 12 Nov 2004 20:48:21 GMT, "Paul Stamler"
wrote:

Hi folks:

Let me launch a trial balloon here. Is this a DIY project that appeals to
you?

It's a microphone preamp, solid state, transformer in (Jensen),

...

I'd make my slice selling the PC boards and
writing it up for the magazines.

Speaking of PC boards, would it be all thru-hole, or any surface
mount? You're of course aware that more and more parts are only
available in SMT thesedays, and some people won't want to solder SMT
parts (even though the .050 pitch pins aren't hard). Or does it depend
on IC options? You could make a dual thru-hole/surface mount layout
for the chips that come in both.
FWIW, I probably won't build it, though I may buy the magazine you
publish it in.


Any interest?

Peace,
Paul


-----
http://mindspring.com/~benbradley

On Fri, 12 Nov 2004 20:48:21 GMT, "Paul Stamler"
wrote:

Hi folks:

Let me launch a trial balloon here. Is this a DIY project that appeals to
you?

It's a microphone preamp, solid state, transformer in (Jensen),

...

I'd make my slice selling the PC boards and
writing it up for the magazines.

Speaking of PC boards, would it be all thru-hole, or any surface
mount? You're of course aware that more and more parts are only
available in SMT thesedays, and some people won't want to solder SMT
parts (even though the .050 pitch pins aren't hard). Or does it depend
on IC options? You could make a dual thru-hole/surface mount layout
for the chips that come in both.
FWIW, I probably won't build it, though I may buy the magazine you
publish it in.


Any interest?

Peace,
Paul


-----
http://mindspring.com/~benbradley

Geoff Wood wrote:

I'd be more interested in variable input impedence.

Which reminds me of a question that came up on another
forum. Seems that pre impedences are down in the 2K Ohm and
below range. Have they always been that low and why such a
relatively big load?


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

Geoff Wood wrote:

I'd be more interested in variable input impedence.

Which reminds me of a question that came up on another
forum. Seems that pre impedences are down in the 2K Ohm and
below range. Have they always been that low and why such a
relatively big load?


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

"Scott Dorsey" wrote in message
...

About half of the cost of the preamp actually is in the power supply, and
I
worked very hard to try and bring the power supply parts cost down and try
and do it entirely with Digi-Key parts. I was not able to do so.
Everything
I did to cut corners in the supply wound up affecting the sound too much.

Scott, try Allied. The new catalog has a surprising number of
tube-compatible power transformers. Combine them with Digi-Key plus a tube
supplier and you may bring the number of suppliers down to three.

Peace,
Paul

"Scott Dorsey" wrote in message
...

About half of the cost of the preamp actually is in the power supply, and
I
worked very hard to try and bring the power supply parts cost down and try
and do it entirely with Digi-Key parts. I was not able to do so.
Everything
I did to cut corners in the supply wound up affecting the sound too much.

Scott, try Allied. The new catalog has a surprising number of
tube-compatible power transformers. Combine them with Digi-Key plus a tube
supplier and you may bring the number of suppliers down to three.

Peace,
Paul

"Ben Bradley" wrote in message
...

I'd make my slice selling the PC boards and
writing it up for the magazines.

Speaking of PC boards, would it be all thru-hole, or any surface
mount? You're of course aware that more and more parts are only
available in SMT thesedays, and some people won't want to solder SMT
parts (even though the .050 pitch pins aren't hard). Or does it depend
on IC options? You could make a dual thru-hole/surface mount layout
for the chips that come in both.

Through-hole. I'm too shaky to solder SMT myself.

The ICs are nothing exotic, and available in 8-DIPs.

Peace,
Paul