Hi Z --> Lo Z transformator

[SteikBacon]

I'm thinking of making a option for my bass to convert the high impedance signal to low for using directly on mixer.
NO BATTERY!!!
I know I have read something about it but don't remember where, and my computer crashed so much of info i collected are lost.

Have not much time to search or experiment anymore so does anyone know where and which transformator that will work?

[potatofarmer]

Direct Boxes | Sweetwater.com

[J M Fahey]

Problem is, if your Bass is a conventional passive one, pickups will expect to see 1M input impedance, at most 220K, definitely not less.

That's a very difficult transformer to wind.

There are ones meant for Direct Boxes but the fully passive ones
usually expect to be driven from a line out, active pickups or some dedicated pre everything Direct Out.

Mind you, if you plug your Bass direct int one of them, sound will come ouit, no doubt, and you may even like it, but will definitely lose punch.

Here are the specs of a high quality German made one:

PMT02 Palmer PRO PMT 02 - Balancing Transformer 10:1 for DI Boxes

PMT 02
Balancing Transformer 10:1 for DI Boxes

The "classic" DI box transformer with a 10:1 ratio. Electrostatic and mu-metal shielding, PCB mount. Technical specifications: Input: 20,000 ohms Output : 200 ohms Frequency range: 30 Hz - 20 kHz, +/- 1 dB Level: + 10 dB into 20,000 ohms max. Dimensions: (without pins): 30 x 30 x 20 mm

[tedmich]

JENSEN TRANSFORMERS, INC. - DIRECT BOX TRANSFORMERS

http://www.jensen-transformers.com/as/as007.pdf

[Mike Sulzer]

If this mixer has a really good mic preamp. it might be possible to add a series/shunt pad in front of this high quality transformer you desribed and still get sufficient SNR. 220K/22K might be high enough for the bass and low enough for the transformer. I would hate to throw away signal, but there might be enough available from the bass.

Problem is, if your Bass is a conventional passive one, pickups will expect to see 1M input impedance, at most 220K, definitely not less.

That's a very difficult transformer to wind.

There are ones meant for Direct Boxes but the fully passive ones
usually expect to be driven from a line out, active pickups or some dedicated pre everything Direct Out.

Mind you, if you plug your Bass direct int one of them, sound will come ouit, no doubt, and you may even like it, but will definitely lose punch.

Here are the specs of a high quality German made one:

PMT02 Palmer PRO PMT 02 - Balancing Transformer 10:1 for DI Boxes

[bbsailor]

I'm thinking of making a option for my bass to convert the high impedance signal to low for using directly on mixer.
NO BATTERY!!!
I know I have read something about it but don't remember where, and my computer crashed so much of info i collected are lost.

Have not much time to search or experiment anymore so does anyone know where and which transformator that will work?

Try using the shure A95U mic matching transformer. http://www.shure.eu/dms/shure/produc...user_guide.pdf

Obtain a 1/4 inch male adapter or use a short (1 ft) male/male cable ends on the A95U female connector. Plug the high impedance side directly into the Bass and run a two conductor, shielded microphone shielded cable from the transformer low-Z XLR output into a mic mixer XLR input. This will allow longer cable runs with minimal effect of the cable capacitance affecting the pickup frequency response. This microphone transformer has a 41k ohm input impedance with about 150 ohms on the low impedance side but since the actual mic input impedance is about 2K ohms at the mixer input, the actual input impedance will be higher in this setup.

I hope this helps?

Joseph Rogowski

[SteikBacon]

Have anyone tried to make a pickup for going directly to mixer. Leaving the need for transformator..

[g1]

Commonly this is done with active pickups (battery required), but see also: low impedance pickups

[Mike Sulzer]

The bass response should be better than specified because the pickup source impedance is low at low frequencies, allowing it to drive the magnetizing inductance of the transformer better than a resistive source of, or near, the nominal impedance. This should work well. It might even be possible to use the largest step down ratio (green/orange). to give the highest load on the pickup at resonance.

If you want the bass to sound as it does when plugged into an amp using a cable, you might want to consider using a cable of similar length from the bass to the transformer to keep the resonance the same. (or not if you like extended response as Joseph suggests)

Try using the shure A95U mic matching transformer. http://www.shure.eu/dms/shure/produc...user_guide.pdf

Obtain a 1/4 inch male adapter or use a short (1 ft) male/male cable ends on the A95U female connector. Plug the high impedance side directly into the Bass and run a two conductor, shielded microphone shielded cable from the transformer low-Z XLR output into a mic mixer XLR input. This will allow longer cable runs with minimal effect of the cable capacitance affecting the pickup frequency response. This microphone transformer has a 41k ohm input impedance with about 150 ohms on the low impedance side but since the actual mic input impedance is about 2K ohms at the mixer input, the actual input impedance will be higher in this setup.

I hope this helps?

Joseph Rogowski

[dai h.]

Index of /pdf/Jensen_Transformers/JE_RE_JT_Direct_Box_DI_Transformers

(as I understand it) the thin wire, complicated winding(to keep capacitance down), production know how, implementation (expensive winders) etc. inevitably make them more expensive. (Also, note that driving impedances and terminating impedances affect their frequency response. Incorrect loading could make the sound worse by causing high frequency ringing leading to clipping of the mic pre and intermodulation distortion (I think)).

Overall, it might be cheaper and easier to just buy a (new or used) direct box (consider an active one if not hell bent on having a passive interface). (Outboard) mic pres can have high impedance inputs that are suitable for basses also.


(link might be of interest in re: to installing BAL output into guitars/bass guitars) ) :

Naiant Studio - Guitar Wiring

[David King]

I used to put a lot of balance transformers into my basses and I'd tested several before I settled on the Richenbach DI transformer from Cinemag.
Audio Transformers By Cinemag Inc. The CM-DBX is the one I used and it cost about $50.

[SteikBacon]

I guess I rather should look for an active DI than solving this by being creative using transformers. But to follow the transformer idea. Could we use more transformers, connect the hiZ in series, adding to higher impedance, to meet the required load the pickup should have. Then the output of them could be connected series/parallell to the lower/correct impedance.

[charrich56]

I guess I rather should look for an active DI than solving this by being creative using transformers. But to follow the transformer idea. Could we use more transformers, connect the hiZ in series, adding to higher impedance, to meet the required load the pickup should have. Then the output of them could be connected series/parallell to the lower/correct impedance.

Yes, you can, in exactly the way you describe. For practical and cost reasons I wouldn't use more than two transformers. Honestly, after a certain point of trial and experimentation, you would be better off IMHO for your time and trouble just getting an active DI box as you are thinking.

The big issue with passively transforming back to low impedance isn't signal level but that you might need a transformer (or two) that is not a standard part, to get the loading and therefore tone you would like, even if you stack two of them and play with winding taps. So you may shoot 100+ bucks and 10-20+ hours of your time and still not get something you are satisfied with. However, it could work and the earlier posts have some good suggestions. But in general quality transformers are expensive.

Just as a thought, just about any clean stompbox preamp or "clean boost" pedal advertised to work with bass would give a low impedance signal which you could pad down at the stompbox, inline (inline pad) and/or at the mixer itself, and would work fine.

Seriously, active DI , onboard preamp (there are some great ones out there for bass, e.g. Audere, Bartolini, et al), or an external stompbox preamp would be the best ways to skin the cat.

-Charlie