Would you build this DIY project?

Archived from groups: rec.audio.pro (More info?)

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),
transformerless balanced +4dBu out with a separate -10dBV unbalanced out. IC
based, up to 8 channels in a 2U case, plus separate power pack. Phantom on
all channels, 100Hz rolloff selectable on all channels, otherwise no EQ.
Designed to be comparable to the Sytek in price, performance and feature
set, but with transformer-coupled inputs. All parts obtainable (to North
Americans, at any rate) from Digi-Key and Allied Electronics, except for the
transformers, which come directly from Jensen. On-card regulation. Like the
Sytek, there are some optional choices in what ICs you use.

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.; 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

Power Supply: $120.00

So a 4-channel unit would cost almost exactly $1k, not counting boxes. An
8-channel would be $1880, ditto. I'd make my slice selling the PC boards and
writing it up for the magazines.

Any interest?

Peace,
Paul

Archived from groups: rec.audio.pro (More info?)

In article <pk9ld.891630$Gx4.439542@bgtnsc04-news.ops.worldnet.att.net> pstamlerhell@pobox.com writes:

> 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),
> transformerless balanced +4dBu out with a separate -10dBV unbalanced out. IC
> based, up to 8 channels in a 2U case, plus separate power pack. Phantom on
> all channels, 100Hz rolloff selectable on all channels, otherwise no EQ.
> Designed to be comparable to the Sytek in price, performance and feature
> set, but with transformer-coupled inputs.

> So a 4-channel unit would cost almost exactly $1k, not counting boxes. An
> 8-channel would be $1880, ditto. I'd make my slice selling the PC boards and
> writing it up for the magazines.

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'm really Mike Rivers (mrivers@d-and-d.com)
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 here: double-m-eleven-double-zero at yahoo

Archived from groups: rec.audio.pro (More info?)

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

cheers

garrett


On 2004-11-12 17:37:14 -0800, mrivers@d-and-d.com (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>

Archived from groups: rec.audio.pro (More info?)

You might try bouncing this around at the 'lab' forum at prodigy. There
is a lot of pro audio DIY stuff going on there.

http://www.prodigy-pro.com/forum/index.php

Brian



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),
> transformerless balanced +4dBu out with a separate -10dBV unbalanced out. IC
> based, up to 8 channels in a 2U case, plus separate power pack. Phantom on
> all channels, 100Hz rolloff selectable on all channels, otherwise no EQ.
> Designed to be comparable to the Sytek in price, performance and feature
> set, but with transformer-coupled inputs. All parts obtainable (to North
> Americans, at any rate) from Digi-Key and Allied Electronics, except for the
> transformers, which come directly from Jensen. On-card regulation. Like the
> Sytek, there are some optional choices in what ICs you use.
>
> 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.; 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
>
> Power Supply: $120.00
>
> So a 4-channel unit would cost almost exactly $1k, not counting boxes. An
> 8-channel would be $1880, ditto. I'd make my slice selling the PC boards and
> writing it up for the magazines.
>
> Any interest?
>
> Peace,
> Paul
>
>

Archived from groups: rec.audio.pro (More info?)

"Richard Crowley" <rcrowley7@xprt.net> wrote in message
news:10papfq9fbrr228@corp.supernews.com...
> "Paul Stamler" wrote ...
> > Let me launch a trial balloon here. Is this a DIY project that
> > appeals to you?
>
> Yes, it would appeal to me as a DIY project.
> I'd appreciate a bit more detail on the $220/channel costing.

Uh, whoops -- I added something in twice. The cost would be closer to
$175/channel. The design is a slimmed-down version of the "project-r" preamp
I published in Recording several years ago. So 4 channels would cost $700,
plus $140 for the power supply (that just went up -- sorry, this is still
not quite a finished design) and whatever you wanted to spend for the boxes.
$840 total; $1540 for 8 channels.

The $175/channel breaks down this way (all figures rounded to nearest US$):

Circuit board - $25 (that part's guesswork).

Transformer - $67.

Stage 1 - $33-36, depending on choice of chip. The bulk of that cost is the
XLR, level control, and switches for the bass rolloff and the phantom
on/off.

Stage 2 - $15.

Balanced output - $16.

On-card regulators - $18.

About the raw supply for $120: I freely admit it's over-designed. In the
previous design I had a fairly normal power supply (with tons of
capacitance) and a very fancy, two-stage regulator (317/337 pre-regulators
in the box, plus Sulzer-type op-amp+pass-transistor regulators on the cards.
That was fun, but it led some builders to problems; the same circuits that
stayed perfectly stable for me, oscillated like crazy for them. Turns out I
was using an older version of the 5534 chip in the regulators (Signetics),
which is no longer available. The new ones are less stable in that circuit.
Most of the folks who built the preamp ended up using TL071s in the
regulators. But I digress.

The new raw supply is one which pays somewhat fanatical attention to
RFI-proofing, including filtering out the crud that comes from the diodes'
switching off, and it incorporates some interesting things I learned about
capacitors while researching an article which audioXpress will, I hope,
manage to get into print soon. You probably could save several dollars on it
if you have a good source of surplus 48VCT transformers handy. Or surplus
5-pin XLRs, chassis and cable mount, for the umbilicus.

There are other ways of spending less on this design, notably by omitting
the bass rolloff and/or phantom switches. There are a few ways of spending
more, too, and getting higher performance, including fancier opamps in Stage
2 and substituting an LT1085 regulator for the LM317 on each card.

Anyway, that's the bottom line, or family of them: About $175 for each
channel, assuming my PC board number is right, about $140 for the power
supply. Add boxes.

As to Scott's suggestion of going transformerless: Why? For about the same
amount of money I can get 4 or 8 channels of Sytek, which is excellent. The
point of this design is to give a similar level of performance for those of
us who want to use transformer-coupled inputs, for reasons of RFI-proofness,
loading, whatever.


Peace,
Paul

Archived from groups: rec.audio.pro (More info?)

"Paul Stamler" <pstamlerhell@pobox.com> wrote in message news:<pk9ld.891630$Gx4.439542@bgtnsc04-news.ops.worldnet.att.net>...
> Hi folks:
>
> Let me launch a trial balloon here. Is this a DIY project that appeals to
> you?

(snip)

Hi.

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. 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.
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. I don't have the time or inclination to order parts from 4
different sources, hunt for a suitable chassi, deal with back-orders
and replacements, pay $30 in shipping for 3 resistors etc.
I know you guys don't want to turn your kitchen into a stocking room
for Digi-key parts, but I'm telling you - when I read "You have to
order this and that from here and there plus machine your own case" I
simply flip the page. And I'm not alone.


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".
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.

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.

-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.

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

/Magnus

Archived from groups: rec.audio.pro (More info?)

In article <d087955e.0411130816.249b589@posting.google.com>,
magnus_jansen@yahoo.com (Magnus Jans?n) wrote:

> "Paul Stamler" <pstamlerhell@pobox.com> wrote in message
news:<pk9ld.891630$Gx4.439542@bgtnsc04-news.ops.worldnet.att.net>...
> > Hi folks:
> >
> > Let me launch a trial balloon here. Is this a DIY project that appeals to
> > you?
>
> (snip)

[snip]
> 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 comment hits at the key (potential) problem I see with this project.
Conceptually, it seems similar to the Seventh Circle and Hamptone kits.
The difference seems to be that you are suggesting "comparable to Sytek"
performance. I haven't used the Sytek, but most commenters here suggest
it's "mid-range" in quality. The Seventh Circle preamps aim for "Neve" and
"API" quality, which is clearly a step up. Those guys also offer complete
kits with all the parts, including chassis.

These comments are not meant to dog your idea, just pointing out what's
available and (somewhat) comparable to your idea. It seems to me that,
while the other guys do have a higher cost per channel, they are offering
complete kits and (alleged) higher quality. For myself, given the only
moderate cost differences between your suggested kit and the others, I
would probably buy the Hamptone or Seventh Circle kits; if I'm going to
take the time to build it, I want something as good as (or
better/different) than what I have now (API).

Hamptone and 7C also seem to offer pretty good tech support; are you
looking to do this as an ongoing business where the sales volume is strong
enough to provide comparable support? If not, the other alternative might
be to offer a "PC board only" kit, or a kit with the board and a few
critical parts.

--
Jedd Haas - Artist
http://www.gallerytungsten.com
http://www.epsno.com

Archived from groups: rec.audio.pro (More info?)

"Paul Stamler" <pstamlerhell@pobox.com> wrote in message
newsk9ld.891630$Gx4.439542@bgtnsc04-news.ops.worldnet.att.net...
> 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),
> transformerless balanced +4dBu out with a separate -10dBV unbalanced
out. IC
> based, up to 8 channels in a 2U case, plus separate power pack.
Phantom on
> all channels, 100Hz rolloff selectable on all channels, otherwise no
EQ.
> Designed to be comparable to the Sytek in price, performance and
feature
> set, but with transformer-coupled inputs. All parts obtainable (to
North
> Americans, at any rate) from Digi-Key and Allied Electronics, except
for the
> transformers, which come directly from Jensen. On-card regulation.
Like the
> Sytek, there are some optional choices in what ICs you use.
>
> 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.; 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
>
> Power Supply: $120.00
>
> So a 4-channel unit would cost almost exactly $1k, not counting
boxes. An
> 8-channel would be $1880, ditto. I'd make my slice selling the PC
boards and
> writing it up for the magazines.

None whatsoever. There are already too many high-priced mike preamps
on the market (from the point of view of manufacturers.) If you want
to design something useful, come up with a battery operated unit at
$50/channel.

Norm Strong

Archived from groups: rec.audio.pro (More info?)

<Garrett Cox> wrote in message
news:2004111217503816807%@news.speakeasy.net...
> How much to build the powersupply? I assume we'd be building it. I'd
be
> interested. I love reading the DIY also. Still want to piece
together a
> few of Scott Dorsey's passive EQ's. I hope it'd sound pretty awesome
> 220 per channel is a bit of cash. I won't say steep but it is a DIY
> project for almost 2 grand. (If you do 8 channels)
>
> mark me down for interest peaked.

I think the word you're looking for there is 'piqued'.

Archived from groups: rec.audio.pro (More info?)

"Magnus Jans?n" <magnus_jansen@yahoo.com> wrote in message
news087955e.0411130816.249b589@posting.google.com...

> First, I want to be able to get ALL parts at once from one place, and
> that must include the chassis. 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.
> 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. I don't have the time or inclination to order parts from 4
> different sources, hunt for a suitable chassi, deal with back-orders
> and replacements, pay $30 in shipping for 3 resistors etc.
> I know you guys don't want to turn your kitchen into a stocking room
> for Digi-key parts, but I'm telling you - when I read "You have to
> order this and that from here and there plus machine your own case" I
> simply flip the page. And I'm not alone.

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.

> 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".
> 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.

Very good point. In this design, you can leave out whatever you don't want;
leaving out the high-pass filter will save $5-something per channel (the
price of the switch), leaving out the balanced outputs will save about $16
per channel. By leaving the phantom on all the time (global on/off switching
only), you save another $5-something. So a stripped-down version would cost
about $148 a channel.

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

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?

Peace,
Paul

Archived from groups: rec.audio.pro (More info?)

"Jedd Haas" <jnh@epsno.com> wrote in message
news:jnh-1311041117460001@192.168.0.101...

> > 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 comment hits at the key (potential) problem I see with this project.
> Conceptually, it seems similar to the Seventh Circle and Hamptone kits.
> The difference seems to be that you are suggesting "comparable to Sytek"
> performance. I haven't used the Sytek, but most commenters here suggest
> it's "mid-range" in quality. The Seventh Circle preamps aim for "Neve" and
> "API" quality, which is clearly a step up. Those guys also offer complete
> kits with all the parts, including chassis.
>
> These comments are not meant to dog your idea, just pointing out what's
> available and (somewhat) comparable to your idea. It seems to me that,
> while the other guys do have a higher cost per channel, they are offering
> complete kits and (alleged) higher quality. For myself, given the only
> moderate cost differences between your suggested kit and the others, I
> would probably buy the Hamptone or Seventh Circle kits; if I'm going to
> take the time to build it, I want something as good as (or
> better/different) than what I have now (API).

The Hamptone is in a different category; it's a "color" preamp rather than
an attempt at a neutral preamp. This, like the Sytek, aims for neutral. I
haven't checked out the Seventh Circle units.

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.

> Hamptone and 7C also seem to offer pretty good tech support; are you
> looking to do this as an ongoing business where the sales volume is strong
> enough to provide comparable support? If not, the other alternative might
> be to offer a "PC board only" kit, or a kit with the board and a few
> critical parts.

One of the latter options. I'd sell, I think, PC boards and matched
resistors for the phantom power. And I'd provide lots of hand-holding to
anyone with problems; I just spent several months online debugging one of
the older designs with a guy who built it and had problems. Eventually I had
him ship it to me, and it spent a lot of time on my bench. (That was how I
found out the newer batches of 5534s aren't as stable in regulators.) I'd do
that for anyone who bought a PC board from me, for sure.

Peace,
Paul

Archived from groups: rec.audio.pro (More info?)

"agent86" <maxwellsmart@control.gov> wrote in message
newsLsld.21427$z3.19754@bignews5.bellsouth.net...
>
> 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

Archived from groups: rec.audio.pro (More info?)

On 2004-11-13, Mike Rivers <mrivers@d-and-d.com> 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.

Archived from groups: rec.audio.pro (More info?)

....

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

Archived from groups: rec.audio.pro (More info?)

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

Archived from groups: rec.audio.pro (More info?)

In article <d087955e.0411130816.249b589@posting.google.com> magnus_jansen@yahoo.com 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 (mrivers@d-and-d.com)
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 here: double-m-eleven-double-zero at yahoo

Archived from groups: rec.audio.pro (More info?)

Frank Vuotto <deepthrob@hotmail.com> wrote:
>On 13 Nov 2004 17:06:49 -0500, kludge@panix.com (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."

Archived from groups: rec.audio.pro (More info?)

"Paul Stamler" <pstamlerhell@pobox.com> 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

Archived from groups: rec.audio.pro (More info?)

On Fri, 12 Nov 2004 20:48:21 GMT, "Paul Stamler"
<pstamlerhell@pobox.com> 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

Archived from groups: rec.audio.pro (More info?)

"Scott Dorsey" <kludge@panix.com> wrote in message
news:cn6bed$m62$1@panix2.panix.com...

> 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

Archived from groups: rec.audio.pro (More info?)

Sorry yes "piqued" Had a few drinks and was in a hurry. Piqued.

cheers

garrett

On 2004-11-13 10:04:50 -0800, "normanstrong" <normanstrong@comcast.net> said:

>
> <Garrett Cox> wrote in message
> news:2004111217503816807%@news.speakeasy.net...
>> How much to build the powersupply? I assume we'd be building it. I'd
> be
>> interested. I love reading the DIY also. Still want to piece
> together a
>> few of Scott Dorsey's passive EQ's. I hope it'd sound pretty awesome
>> 220 per channel is a bit of cash. I won't say steep but it is a DIY
>> project for almost 2 grand. (If you do 8 channels)
>>
>> mark me down for interest peaked.
>
> I think the word you're looking for there is 'piqued'.

Archived from groups: rec.audio.pro (More info?)

In article <slrncpcvuj.ldv.fishbowl@radagast.home.conservatory.com> fishbowl@conservatory.com writes:

> 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.

I've heard of this outfit but have never investigated them. Why not
get an estimate for a project like this and pass it on to us? Don't
forget holes for the gain controls, high pass filter and phantom power
switches, might as well add a polarity switch, power supply connector,
and both inputs and outputs. Would you put the inputs on the front
(for convenience) or on the rear (for convenience <g> ). That's two
panels, in case you weren't counting.

Do they make aluminum panels suitable for rack mounting that can
support the weight of eight transformers? (yeah, I know, it makes a
difference whether you mount them near the front or back). You'd
probably want a 3/16" or 1/4" thick front panel if that was also the
rack mount point, or at least an 1/8" panel with add-on rack ears.
Then you'd need a chassis and stand-offs to mount the circuit board.
All in all, a fair number of mechanical parts. This is why companies
that build electronic equipment have mechanical engineers working for
them, at least as consultants.




--
I'm really Mike Rivers (mrivers@d-and-d.com)
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 here: double-m-eleven-double-zero at yahoo

Archived from groups: rec.audio.pro (More info?)

Kurt Albershardt <kurt@nv.net> wrote:
>Mike Rivers wrote:
>>
>> 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?

No, he is talking about round Greenless punches, without holes for mounting
screws. You punch the hole, put in the connector, and then drill the screw
holes.

I did not know that there were ANY hand punches that will do all three holes
in one operation! If you know of one, I would really like to know. I have
used a small hydraulic press with custom tooling, a combination that cost a
lot more than $200 and was not convenient to take into the field. A hand punch
that would do all three holes would be wonderful for field modification work.
--scott

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

Archived from groups: rec.audio.pro (More info?)

"Mike Rivers" <mrivers@d-and-d.com> wrote in message
news:znr1100391373k@trad...
>
> Mr. Marketing here . . .
>
> How about presenting it as a two-channel preamp which, I suspect, is
> more in demand than an eight-channel preamp. Make a two-channel board
> with pads to mount components for phantom powering, the high-pass
> filter, and the additional components for the balanced output. Let the
> user decide what extra features he wants to add for more flexibility
> rather than what features he wants to leave out to save a few bucks.
> The power supply will handle up to eight channels worth of boards, so
> the preamp can grow as the users' needs grow.

It's already a two-channel preamp if you only buy two preamp boards. And
since the users are buying the parts, they get to decide what to leave out.
I'll make it clear, if I market the boards, just what parts are mandatory
and what parts aren't.

> The chassis, panel, and case will remain a stumbling block for many,
> however.

But not all; I'm aiming this at folks who have had at least some experience
with DIY. And I have a guy who's willing to make and sell panels and/or
cases. If someone wanted fewer than 8 channels, they could always put plugs
into the unused front-panel holes.

Peace,
Paul

Archived from groups: rec.audio.pro (More info?)

On 14 Nov 2004 06:59:08 -0500, mrivers@d-and-d.com (Mike Rivers)
wrote:

>The chassis, panel, and case will remain a stumbling block for many,
>however.


Amen, even for the experienced it usually takes twice as long to box
a project as it does to put together a circuit or perf board.


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