A musician friend of mine gave me a handful of these transformers:
Altronics - M0705 600 Ohm : 10k Ohm Shielded Microphone Transformer
The wiring diagram is here:
http://www.altronics.com.au/download/Datasheets/M0705.pdf
What kind of purpose would these serve for home/diy audio?
Altronics - M0705 600 Ohm : 10k Ohm Shielded Microphone Transformer
The wiring diagram is here:
http://www.altronics.com.au/download/Datasheets/M0705.pdf
What kind of purpose would these serve for home/diy audio?
Thanks. I have a preamp with an XLR output, also a dac which has a passive I/V stage, so the transformers might be of some use.
The 'datasheet' has so little detail! What is this transformer actually doing (besides impedance matching)? Is there any gain provided?
The 'datasheet' has so little detail! What is this transformer actually doing (besides impedance matching)? Is there any gain provided?
if you use the 600 ohm side as input, then you have gain....
you can try to use that for an MC step-up transformer....
you can try to use that for an MC step-up transformer....
Ok great, how do we calculate the gain?
For example, my balanced dac puts out 1ma per channel, with 10R iv resistors we get: 10 x 0.001 = 0.01vrms. Tiny!
At the moment I run this into a 30db gain tube amp, which drives a push pull power amp (100k input impedance) quite well.
Could these transformers be used to replace the line stage tube pre?
For example, my balanced dac puts out 1ma per channel, with 10R iv resistors we get: 10 x 0.001 = 0.01vrms. Tiny!
At the moment I run this into a 30db gain tube amp, which drives a push pull power amp (100k input impedance) quite well.
Could these transformers be used to replace the line stage tube pre?
Front end Phase splitter for tube amp? Isn't this like a Lundahl LL1690? Like what would be used for the Pete Millet Universal Driver board?
Heck, if so, I may want a pair for a couple experiments....too bad I am across teh pond.
Thinking of using the Edcor 600/10k or 10k/10k transformers too...
Heck, if so, I may want a pair for a couple experiments....too bad I am across teh pond.
Thinking of using the Edcor 600/10k or 10k/10k transformers too...
Last edited:
I have a few lundahl trannies (not for the same purpose), so should be in a position to give a good comparison on the sound signature.....if I can find a good use for these units!!
Out of interest, how would one wire up an unbalanced input and output to these trannies?
Out of interest, how would one wire up an unbalanced input and output to these trannies?
there are other reasons for using the traffo aside from gain..
galvanic isolation can be useful in eliminating ground loops...
Ok well I'll test it out on an old linestage and see how they sound. Whhat would the wiring be for an unbalanced input/output?
red, + in
green, input return connected at the ground terminal of the input connector
yellow, + out
blue, output ground connected to the amplifiers ground reference
For more gain black may be used instead of red, otherwise black should not be connected! (Gain will be about 8 or 18.23908741 dB.)
green, input return connected at the ground terminal of the input connector
yellow, + out
blue, output ground connected to the amplifiers ground reference
For more gain black may be used instead of red, otherwise black should not be connected! (Gain will be about 8 or 18.23908741 dB.)
Ok great, thanks for the help, I'll wire up a test circuit and report on the sound.
If I'm using a 10r source load resistor, what will the output impedance be?
How are you folks calculating the gain without the turns ratio, etc? How was it possible to know of the difference in gain between the red and blue wires?
Transformers sure are amazing (especially when they're as cheap as these ones!).
If I'm using a 10r source load resistor, what will the output impedance be?
How are you folks calculating the gain without the turns ratio, etc? How was it possible to know of the difference in gain between the red and blue wires?
Transformers sure are amazing (especially when they're as cheap as these ones!).
Just finished the 'test circuit'. I wired them up as per Simon7000's recommendation above (black wire), and put them between a dac (10R passive i/v) and a preamp (100k input impedance). Result; roughly 20dB gain, sonics are good but obviously the transformers are not burned in as yet (although I must say there's definitely no degradation).
Ther are some other important parameters that restrict the field of utilization: main inductance, stray inductance, wire resistance. E. g. the inductance determines the lower cutoff frequency with a given source resistance. I measured the LL1678 primary inductance 160 mH that gives 20 Hz cutoff with 20 ohms source.
How did you measure the inductance?
With a 600:10k ratio, how do we calculate the output impedance when using the centre tap as the input hot wire (as opposed to the 'red' wire in the circuit diagram)?
With a 600:10k ratio, how do we calculate the output impedance when using the centre tap as the input hot wire (as opposed to the 'red' wire in the circuit diagram)?
Using a parallel 100nF capacitor on the side with lower turns, and a series resistor (10k) I measured the resonance peak, and calculated the resonant frequency.
OK great, I shall have to try it and test.
Well after a few days of listening, I must admit that I really can’t notice the difference (apart from the additional gain) when the transformers in the circuit. They are highly transparent (within the confines of my system!).
If the ratio is 600:10K, does this mean that with a 10R input load, the output impedance is 166R?
On another note, how would one go about matching these transformers? They’re cheap enough that one could buy three of four to match a pair. Main reason for doing this would be that generalist audio gear made at Tandy, Jaycar, etc, probably has questionable quality control.
Well after a few days of listening, I must admit that I really can’t notice the difference (apart from the additional gain) when the transformers in the circuit. They are highly transparent (within the confines of my system!).
If the ratio is 600:10K, does this mean that with a 10R input load, the output impedance is 166R?
On another note, how would one go about matching these transformers? They’re cheap enough that one could buy three of four to match a pair. Main reason for doing this would be that generalist audio gear made at Tandy, Jaycar, etc, probably has questionable quality control.
Hi,
They can be used to convert fairly standard phono out/in
audio kit to balanced XLR that allows much longer cables.
rgds, sreten.
They can be used to convert fairly standard phono out/in
audio kit to balanced XLR that allows much longer cables.
rgds, sreten.
Yes, but with a severely compromised frequency response at LF.lordearl said:
A little reading on transformers may help you get the best out of them. They don't provide power gain, just impedance matching and ground isolation. The voltage gain can be useful, but it isn't real gain - just a transformed impedance.
- Status
- Not open for further replies.