transformer recommendations for a parametric eq ?

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capnspoony

Well-known member
Joined
Apr 29, 2006
Messages
400
Location
brooklyn, NY
im looking for a good 1:1 trafo to add some beef to this circuit to make it
balanced...

http://www.ethanwiner.com/spect-3.jpg

i have added a voltage follower at the output in order to drive an output transformer but am unsure of what ratio i should use and what brand of transformers i should be looking into this ..

anybody have any suggestions?

cheers
-richie :thumb:
 
It depends upon how beefy your "voltage follower" is. If it can drive 600 Ohms without complaint, than a simple 600:600 transfo is the obvious choice. If it can drive 150 Ohms, than a 150:600 will act as a voltage step-up for increased output level before clipping.

If price is important, the Edcor iron is a good choice. Moving upscale you'll find Cinemag, Jensen and Sowter.

Bri
 
currently i only have my voltage follower providing 1 gain via negative feedback.

how do i determine if that is sufficient enough to provide power for a 600:600 ?

My understanding is that the circuit could drive a 150:600 because it had a 150R resistor as an unbalanced output buffer before.. is this thinking correct?

I'm very new to all of this and trying to grasp the language quickly at the ripe age of 22.

I understand what a transformer does but I'm still unclear about how the ratios are chosen and why.. any further reasoning would be greatly appreciated

thanks for the direction :grin:

cheers
 
What exactly does your voltage follower consist of?

For example, a 553x IC opamp can drive essentially full voltage into a 600 Ohm load.

Here's a simple test that requires an oscillator and oscilloscope. Drive the follower with no load (ie, directly into the 'scope) and adjust the oscillator's output level until the follower is JUST going into clipping with a 1 kHz sine wave. Then, drop a 600 Ohm load across the output of the follower and see if there is any appreciable change in the maximum output voltage at clipping.

If the follower is built around a TL0-7x chip, you WILL observe that the maximum output voltage at clipping into a 600 Ohm load will be considerably less than the maximum voltage at clipping into a higher impedance load.

The issue when driving a 600 (or 150 ) Ohm load is whether or not the driver has enough output current capability. A 553x chip squeaks by into 600 Ohms...a TL0-7x chip does not. Neither can provide full voltage swing into a 150 Ohm load.


Bri
 
hi again bri

*my voltage follower is just a lead from the output of an op amp to the minus pin to yield gain of one

*im using only TL074 ic opamps

*I've been looking to buy a scope but have yet to own one personally. However I'll will be sure to go sneak into school even though I don't go there anymore and try that out. I think that should bring some light on to my understanding of what is physically going on.

*since im using TL074 ic's does I should look into a 600:600 because

voltage at clipping into a 600 Ohm load will be considerably less than the maximum voltage at clipping into a higher impedance load.

?

thanks for another reply :cool:

cheers
-richie
 

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