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Colour-less transformers for a DI box for use with synths Mixers (Digital)
Old 13th January 2018
  #1
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Colour-less transformers for a DI box for use with synths

Hello, my first post this year!

Looking to find details on some DI box transformers which would keep the colouring to minimum.
I know it's sometimes desirable but on this occasion I have other colouring tools.

Also, are there transformers which are better suited for synths and keyboards rather than guitars?

I know they have ratios but I don't know much about how that works.

Any suggestions guys? The idea is to build a DI box with good transformers basically, designed for synths.
Old 13th January 2018
  #2
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Jensen (US) and Lundahl (Sweden) both make very good "inaudible" DI transformers.
Old 13th January 2018
  #3
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OEP or Whirlwind is good enough. I'm pretty sure no one can hear a difference on a keyboard sound (read: on any musical sound), except maybe some trafo fanatic.

Even Behringer DI is pretty clean in these terms - not sounding like "overdrive" even at high volume levels from keyboards.
Old 13th January 2018
  #4
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Quote:
Originally Posted by zvukofor View Post
OEP or Whirlwind is good enough. I'm pretty sure no one can hear a difference on a keyboard sound (read: on any musical sound), except maybe some trafo fanatic.
I'm no fanatic, or even close to golden-eared, but I'm pretty sure anyone could tell the difference in the fullness and bottom end between a Whirlwind and the same passive circuit with a UTC A10 or A11 (which are scarce and pricy but still gettable).
Old 13th January 2018
  #5
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UK

EMO make great passive DI's and Splitters. They probably use Sowter Traffos.
Haufe are also a thing. It's regional.

DD
Old 13th January 2018
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An inexpensive active DI could be cleaner (more linear) than an expensive transformer.

JR

[edit] If the keyboard has a line cord (i.e. not passive like Rhodes) it should have a relatively low source impedance, and an active keyboard could put out significant high amplitude, low frequency bass that is the heavy lifting for transformers. [/edit]

Last edited by JohnRoberts; 13th January 2018 at 07:26 PM..
Old 13th January 2018
  #7
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Quote:
Originally Posted by Brent Hahn View Post
I'm no fanatic, or even close to golden-eared, but I'm pretty sure anyone could tell the difference in the fullness and bottom end between a Whirlwind and the same passive circuit with a UTC A10 or A11 (which are scarce and pricy but still gettable).
On a bass drum? Yes. But UTC is way larger than DI-designed Lundahl, for example. And when using with average -10dBu levels from keyboards - no difference for music job.
Old 13th January 2018
  #8
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Quote:
Originally Posted by zvukofor View Post
On a bass drum? Yes. But UTC is way larger than DI-designed Lundahl, for example. And when using with average -10dBu levels from keyboards - no difference for music job.
How do you DI a bass drum? (kidding)

I have a UTC in one DI and a couple more with JM Magnetics J4's (from an RCA film dubber, also big) and compared to my Whirlwind, they even make the piezo in my ukulele sound fatter.
Old 13th January 2018
  #9
Build yer own, not hard nor expensive. I have a few built with Jensen DB transformers with the thru and switches. The data is on their web site. They always work great with that 180k input impedance. Like any transformer they will slightly soften upper frequency transients but a quality EQ can touch that up. The low end is tight and deep with very low THD and no deviation from linear phase. Plus they are passive and always work.
Old 13th January 2018
  #10
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Old 14th January 2018
  #11
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Quote:
Originally Posted by Jim Williams View Post
Build yer own, not hard nor expensive. I have a few built with Jensen DB transformers with the thru and switches. The data is on their web site.
A really easy way is to buy a cheap Asian DI box like this one ($16.), rip out the crummy transformer and solder in a good one. A plain metal box this nice would cost you more than $20. You can either do what I did, mount the transformer on top and keep the internal PC board, or you can remove the PC board and replace the connectors and put the transformer inside (the Jensen will fit).
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Old 14th January 2018
  #12
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I'm not sure what the application is of the OP. it might not even be needed.
Old 14th January 2018
  #13
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Quote:
Originally Posted by Muser View Post
I'm not sure what the application is of the OP. it might not even be needed.
Actually you're right. If he wants "uncoloured," straight into the converters is the way to go. It is with my rig, anyway. Which is why I don't usually do it.
Old 14th January 2018
  #14
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Quote:
Originally Posted by Brent Hahn View Post
Actually you're right. If he wants "uncoloured," straight into the converters is the way to go. It is with my rig, anyway. Which is why I don't usually do it.
haha. right. that's what I just suddenly thought too.
Old 14th January 2018
  #15
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Quote:
Originally Posted by Muser View Post
haha. right. that's what I just suddenly thought too.
But there are lots of GS threads about "How do I do X to achieve Y?" A bunch of people pile in about how to do X, one guy goes straight to achieving Y, and the Thread Starter says, "I don't just want to achieve Y, I want to achieve Y by doing X."
Old 14th January 2018
  #16
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Quote:
Originally Posted by Brent Hahn View Post
But there are lots of GS threads about "How do I do X to achieve Y?" A bunch of people pile in about how to do X, one guy goes straight to achieving Y, and the Thread Starter says, "I don't just want to achieve Y, I want to achieve Y by doing X."
and many people instantly associate the use case or application of the OP as sound in the first instance.
because we fill in the gaps with our own experiences I guess, and assume our own applications as sound, too.

I remember hearing an explanation of what they call a syndrome. I'm not even sure if it was accurate. or maybe it was translated into some other domain. in any case.

they said, a syndrome is like a policeman who would see everyone as a potential criminal or a hairdresser who would see everyone as a potential haircut.
Old 14th January 2018
  #17
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Quote:
Originally Posted by Muser View Post
... a syndrome is like a policeman who would see everyone as a potential criminal or a hairdresser who would see everyone as a potential haircut.
Right. Like the veterinary dentist who refers to a lion as the "King of Teeth."
Old 14th January 2018
  #18
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Quote:
Originally Posted by Brent Hahn View Post
Right. Like the veterinary dentist who refers to a lion as the "King of Teeth."
I guess so. I suppose I see it as a constant translation of our own experiences into other terms of reference. it's probably why over time, I adapted my thinking to never expect the output to match the input. translation is highly lossy, being always transforming into other terms. I also think that's a fundamental property of Art. I'm often more interested in the mistakes people make than any kind of perfection.
Old 14th January 2018
  #19
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Quote:
Originally Posted by Muser View Post
I'm not sure what the application is of the OP. it might not even be needed.
Indeed... direct boxes were invented to deal with high impedance sources, so like I posted the old Rhodes style keyboards with passive pickups would benefit from a DI (but I still prefer active there).

A modern well designed keyboard with active electronics should be well behaved as is unless the application is dicey, like live performances with questionable stage power.

Does it not work now?

JR
Old 14th January 2018
  #20
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Quote:
Originally Posted by JohnRoberts View Post
Indeed... direct boxes were invented to deal with high impedance sources, so like I posted the old Rhodes style keyboards with passive pickups would benefit from a DI (but I still prefer active there).

A modern well designed keyboard with active electronics should be well behaved as is unless the application is dicey, like live performances with questionable stage power.

Does it not work now?

JR
yeah for stage you might be required to be able to get into XLR feeds and those might be microphone impedance's. in that case it's something you should probably be ready for. I did read on the palmer site, in respect of guitars at least, that for a passive you should choose an active DI and for an active guitar, passive. but that distinction is not something I've investigated or tried even.

for a keyboard I'd just use normal jacks. either balanced or unbalanced, depending on the keyboard. but the ring of a balanced would just be skipped if it's a balanced part of a loom inserted into an unbalanced keyboard. though the ring may then float. however, I usually feed those to a balanced patchbay in either case. so I can turn a balanced to unbalanced by inserting a normal mono cable in the connection loop, when the feed from the keyboard is balanced. and which should serve the same application for unfloating the floating ring for the other condition. but for the OP non of that is stated for the use case. He'd have to clarify his gear and use case. preferably along with his assumption of what He assumes he needs and why. because he might not need any of it.
Old 15th January 2018
  #21
I don't regularly use transformers here but I found the Jensens will nicely "round out" a cheesy synth pad or track. Sort of adds a sense of realism to grand piano patches. Rhodes pianos get active pre amps with a 2.2 meg input impedance (Mk7 designs).
Old 16th January 2018
  #22
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Jensen Iso-Max DB-2PX Two channel direct box
DB-2PX | Jensen Transformers



You did not reveal why you think you need a direct box? (or just isolation transformer(s)?
Could you simply use "impedance-balanced" output?
Old 18th February 2018
  #23
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Well to be honest I fear my yamaha N12 preamps lack oomph.. so I want to put it through some iron before entering the preamps..
Old 20th February 2018
  #24
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Jensen makes excellent xfmrs, like many others are saying.

Jensen had some tech notes on their site explaining that their transformers in the lower 1:1 to 1.5 step-up range were least colored, while their higher step-up values such as the 1:10 JT-115K were most colored. They explained that excess coloration is why they don't like going higher than 1:10 because beyond that, THD is hard to control.

You can see this in the following chart of mic input transformers looking at the THD stats, although surprisingly their 1:1 transformer does not have lowest THD:

Mic Input | Jensen Transformers

You need a line level transformer for synth, so choose one of the following with very low THD:

Line Output Transformers | Jensen Transformers
Old 20th February 2018
  #25
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...and check out radial di boxes: they are using (owning) jensen trafos. you'll find plenty of models (active, passive, mutichannel, splitters etc.) and information on their webpage
Old 20th February 2018
  #26
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Quote:
Originally Posted by AtomicMidi View Post
Well to be honest I fear my yamaha N12 preamps lack oomph.. so I want to put it through some iron before entering the preamps..
No offense intended, but that seems like a very dubious reason for thinking you need an expensive DI box. I have to agree that if you DO need extra gain (?), an active box would very likely be a better choice than expensive iron.
Old 12th March 2018
  #27
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That's fair enough. Thanks for replies guys.
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