I'm interested in taking a Whirlwind IMP2 passive DIY ($35, very simple
rugged construction) and swapping the transformer for a Jensen JT-DBE
or JT-DB-ETC ($73 from Jensen.) By my (maybe naive) estimation this
should yield a DI on par with something like the Radial JDI (for 100
bucks), and there seems to be very little work involved. Am I missing
anything? Has anyone done something like this?
Thanks for any help,

Dan Fox

Daniel Fox wrote:

I'm interested in taking a Whirlwind IMP2 passive DIY ($35, very simple
rugged construction) and swapping the transformer for a Jensen JT-DBE
or JT-DB-ETC ($73 from Jensen.) By my (maybe naive) estimation this
should yield a DI on par with something like the Radial JDI (for 100
bucks), and there seems to be very little work involved. Am I missing
anything? Has anyone done something like this?

Well.... I've *designed* DIs so I guess I'm qualified to comment.

Have you checked the specs of the Jensen transformers against whatever info
you can infer about the original tx ?

I don't know the specs of the Jensen txs you mention but are you
sufficiently electronics savvy to know about turns ratios, impedances and
stuff ?

It may be fine. OTOH do you reckon the stock Whirlwind DI is inadequate ?
What are you seeking to 'fix' by doing this ?


Graham

Daniel Fox wrote:
I'm interested in taking a Whirlwind IMP2 passive DIY ($35, very simple
rugged construction) and swapping the transformer for a Jensen JT-DBE
or JT-DB-ETC ($73 from Jensen.) By my (maybe naive) estimation this
should yield a DI on par with something like the Radial JDI (for 100
bucks),

Yeah, it probably will, but if you're going to make something
equivalent to the Radial, you'll want to put a pad on there, as well as
a polarity reverse switch. The Radial is in a steel box while I think
the Whirlwind is in an aluminum box. That can make a difference where
EMI is concerned. And it's possible that the Jensen transformer may not
fit in the box anyway. Have you measured it?

If you want to build a DI, the Jensen JT-DB-ETC and their application
note is a fine place to start, but why buy a Whirlwind just for the
box? Or, alternatively, if you already have the Whirlwind DI, why scrap
it?

Has anyone done something like this?

If it saves a nickel of purchase cost, you can bet somebody has done
it.

Daniel Fox wrote:
I'm interested in taking a Whirlwind IMP2 passive DIY ($35, very simple
rugged construction) and swapping the transformer for a Jensen JT-DBE
or JT-DB-ETC ($73 from Jensen.) By my (maybe naive) estimation this
should yield a DI on par with something like the Radial JDI (for 100
bucks), and there seems to be very little work involved. Am I missing
anything? Has anyone done something like this?
Thanks for any help,

What you're missing is that if you do this, you've spent a total of
$108 to get something equivalent to a $100 product. Financially this
is not a savings.

Also check and make sure the Jensen transformer will fit inside the
IMP-2. There isn't much space inside those little diecast boxes.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Daniel Fox wrote:
I'm interested in taking a Whirlwind IMP2 passive DIY ($35, very simple
rugged construction) and swapping the transformer for a Jensen JT-DBE
or JT-DB-ETC ($73 from Jensen.) By my (maybe naive) estimation this
should yield a DI on par with something like the Radial JDI (for 100
bucks), and there seems to be very little work involved. Am I missing
anything? Has anyone done something like this?
Thanks for any help,

Dan Fox


My question is, if the Radial is only a hundred bucks, and the transformer is $73, what's your time
worth? While you may be a tweaker, the logic would seem to indicate that you should just cough up
the extra 27 bucks and buy the Radial, which has all the other cool stuff you'll want anyway, right?

So you go without Starbucks for a week; some sacrifices are worth it.

--fletch

Fletch wrote:

My question is, if the Radial is only a hundred bucks, and the transformer is
$73, what's your time worth?

Well, give him a little credit. The Radial JDI is $175 from Mercenary
Audio.

It's a good example of how a product's price is developed, though. Put
a $75 transformer and $10 worth of jacks, switches, and resistors in a
$10 box, add $30 for labor, and by the time you mark it up 50% (not
unreasonable considering the cost of advertising, the distribution
chain, and relatively small quantity sales) and there you go. They
probably don't get a big price break on the parts in the quantities
they build these things, but they can get the box a lot cheaper than
you can, and it's a lot prettier than what you could make yourself.

Give up the profit, pay yourself nothing, and be satisfied with a die
cast aluminum box and, yeah, you can save $75 over the cost of the
Radial.

Mike Rivers wrote:

Fletch wrote:

My question is, if the Radial is only a hundred bucks, and the transformer is
$73, what's your time worth?

Well, give him a little credit. The Radial JDI is $175 from Mercenary
Audio.

It's a good example of how a product's price is developed, though. Put
a $75 transformer and $10 worth of jacks, switches, and resistors in a
$10 box, add $30 for labor, and by the time you mark it up 50% (not
unreasonable considering the cost of advertising, the distribution
chain, and relatively small quantity sales) and there you go. They
probably don't get a big price break on the parts in the quantities
they build these things, but they can get the box a lot cheaper than
you can, and it's a lot prettier than what you could make yourself.

Give up the profit, pay yourself nothing, and be satisfied with a die
cast aluminum box and, yeah, you can save $75 over the cost of the
Radial.

On the subject of how pricing works out, you'll typically find that the higher
quantity selling pro-audio gear retails for about 3 times the cost of the parts
inside it. The manufacturers pay a lot less for the bits inside than you will
though, so it works out as a fair deal. For example the dual op-amps used in the
gear I design cost us I think 15 cents each. Small transistors are ~2 cents. SMD
resistors as little as 1/10 of a cent.

More specialist stuff has a much higher ratio.


Graham

Pooh Bear wrote:
Mike Rivers wrote:

Fletch wrote:

My question is, if the Radial is only a hundred bucks, and the transformer is
$73, what's your time worth?

Well, give him a little credit. The Radial JDI is $175 from Mercenary
Audio.

It's a good example of how a product's price is developed, though. Put
a $75 transformer and $10 worth of jacks, switches, and resistors in a
$10 box, add $30 for labor, and by the time you mark it up 50% (not
unreasonable considering the cost of advertising, the distribution
chain, and relatively small quantity sales) and there you go. They
probably don't get a big price break on the parts in the quantities
they build these things, but they can get the box a lot cheaper than
you can, and it's a lot prettier than what you could make yourself.

Give up the profit, pay yourself nothing, and be satisfied with a die
cast aluminum box and, yeah, you can save $75 over the cost of the
Radial.

On the subject of how pricing works out, you'll typically find that the higher
quantity selling pro-audio gear retails for about 3 times the cost of the parts
inside it. The manufacturers pay a lot less for the bits inside than you will
though, so it works out as a fair deal. For example the dual op-amps used in the
gear I design cost us I think 15 cents each. Small transistors are ~2 cents. SMD
resistors as little as 1/10 of a cent.

More specialist stuff has a much higher ratio.


Graham

Point taken, Mike, regarding my time, but I think we're not talking
about more than half an hour to swap a transformer. And as another
poster mentioned, the Radial does cost about $175. Since my first post
I have found other cheap passive DI's with boxes and jacks of
equivalent quality to the Whirlwind for $20. So we're looking at a no
frills Jensen DI for $93 plus a half hour labor vs. the Radial at $175.
Seems like a worthwhile untertaking to me.
Scotts point about the tranny fitting in the case is a good one. Does
anyone know what exactly the difference is between the 2 Jensen DI
trannys they list on their website? They are the same price and have
identical specs. Anyone know if one of these will fit into a 2" x 2" x
1" space?
Thanks,

Dan

Daniel Fox wrote:

snip

Scotts point about the tranny fitting in the case is a good one. Does
anyone know what exactly the difference is between the 2 Jensen DI
trannys they list on their website? They are the same price and have
identical specs. Anyone know if one of these will fit into a 2" x 2" x
1" space?

Clicking on their model numbers at http://www.jensen-transformers.com/db.html
reveals that the JT-DB-E chassis mounts and the JT-DB-EPC mounts on a printed
circuit board. They're both 1.13" in diameter by 0.85" high.

Please report the results if you do this!

--
================================================== ======================
Michael Kesti | "And like, one and one don't make
| two, one and one make one."
mrkesti at comcast dot net | - The Who, Bargain

On Fri, 02 Sep 2005 16:41:32 -0700, Daniel Fox wrote:

Scotts point about the tranny fitting in the case is a good one. Does
anyone know what exactly the difference is between the 2 Jensen DI trannys
they list on their website? They are the same price and have identical
specs. Anyone know if one of these will fit into a 2" x 2" x 1" space?

A little more time on Jensen's website should answer that. They're known
for being very thorough. If not, send an email to their tech support.
You'll probably have an answer within 24 hours.

The world could do well with a few more companies like that.

Michael R. Kesti wrote:

the JT-DB-E chassis mounts and the JT-DB-EPC mounts on a printed
circuit board. They're both 1.13" in diameter by 0.85" high.

Please report the results if you do this!

Thanks for the info. It may not be for a few weeks but I will report
back.

Dan

Michael R. Kesti wrote:

the JT-DB-E chassis mounts and the JT-DB-EPC mounts on a printed
circuit board. They're both 1.13" in diameter by 0.85" high.

Please report the results if you do this!

Thanks for the info. It may not be for a few weeks but I will report
back.

Dan

Michael R. Kesti wrote:

the JT-DB-E chassis mounts and the JT-DB-EPC mounts on a printed
circuit board. They're both 1.13" in diameter by 0.85" high.

Please report the results if you do this!

Thanks for the info. It may not be for a few weeks but I will report
back.

Dan

Michael R. Kesti wrote:

the JT-DB-E chassis mounts and the JT-DB-EPC mounts on a printed
circuit board. They're both 1.13" in diameter by 0.85" high.

Please report the results if you do this!

Thanks for the info. It may not be for a few weeks but I will report
back.

Dan

sorry bout the quadruple post. Web hang up and reposting confusion.

In article .com,
"Daniel Fox" wrote:

I'm interested in taking a Whirlwind IMP2 passive DIY ($35, very simple
rugged construction) and swapping the transformer for a Jensen JT-DBE
or JT-DB-ETC ($73 from Jensen.) By my (maybe naive) estimation this
should yield a DI on par with something like the Radial JDI (for 100
bucks), and there seems to be very little work involved. Am I missing
anything? Has anyone done something like this?
Thanks for any help,

Dan Fox

I did essentially this about 5 years ago because I wanted a quad DI. I
put 4 of them in a rack mount box. It sounds great and was super easy.
Jensen supplies all you need to know. I have also found that I have
never needed the extra bells and whistles (pad, etc) and rarely have
needed even a ground lift.

Edwin
--
http://www.theetherealplane.com