john12ax7
Well-known member
ruffrecords said:Bottom line the simplest solution not to lose 6dB is to add a transformer to the EQ input.
I agree. No need to overcomplicate things. Edcor is one choice for decent inexpensive transformers.
ruffrecords said:Bottom line the simplest solution not to lose 6dB is to add a transformer to the EQ input.
Or a THAT/INA/SSM debal.ruffrecords said:Bottom line the simplest solution not to lose 6dB is to add a transformer to the EQ input.
I suppose it does imply that's what's happening but it might be a bit of a leap to assume it's like that Rane circuit. The "Tascam problem" is when a circuit like that Rane one is used and the cold output is grounded at the receiving end such that the op amp is driving a 100 ohm load and it causes enough supply stress on the chip that the other op amp (driving the + output) exhibits some distortion. But there could be something about the UA circuit that avoids the distortion and then it's not really a "problem". For example, if the supply has enough headroom, there could be another buildout resistor inside the feedback loop and thus maintain the same output level but limit current in the event the output is shorted. Or it's using some other kind of current limiting arrangement.moamps said:You described it in your reply 33.
What's exactly "Tascam problem"?This schematic is part of a Rane product, I used it only to illustrate how it was done in principle in UA2192.
It is bad practice to drive an active output short circuit into ground. Besides the obvious stress to the ic (which is why less than professional gear often have high output impedances).squarewave said:I suppose it does imply that's what's happening but it might be a bit of a leap to assume it's like that Rane circuit. The "Tascam problem" is when a circuit like that Rane one is used and the cold output is grounded at the receiving end such that the op amp is driving a 100 ohm load and it causes enough supply stress on the chip that the other op amp (driving the + output) exhibits some distortion. But there could be something about the UA circuit that avoids the distortion and then it's not really a "problem". For example, if the supply has enough headroom, there could be another buildout resistor inside the feedback loop and thus maintain the same output level but limit current in the event the output is shorted. Or it's using some other kind of current limiting arrangement.
That is a weird piece of gear though. It's a high-end converter that uses the old crappy Urei construction? It sounds like the marketing department did a focus group while the engineers were out to lunch.
ruffrecords said:Bottom line the simplest solution not to lose 6dB is to add a transformer to the EQ input.
EQ circuitry can be overloaded that way. IMO, better solution is using an unbal/bal output driver.abbey road d enfer said:Or a THAT/INA/SSM
JohnRoberts said:It is bad practice to drive an active output short circuit into ground. Besides the obvious stress to the ic (which is why less than professional gear often have high output impedances).
That current will find it's way back to the PS, if lucky it will only cause a little extra crosstalk. :
I don't see how adding a THAT 1240at the input of an unbalanced circuit can overload it, and how balancing the output of said unbalanced circuit could help it. significantly driving a balanced input.moamps said:EQ circuitry can be overloaded that way. IMO, better solution is using an unbal/bal output driver.
abbey road d enfer said:I don't see how adding a THAT 1240at the input of an unbalanced circuit can overload it, and how balancing the output of said unbalanced circuit could help it. significantly driving a balanced input.....I hope we're all talking about the same...
The schematic for this device show a power rail of over 40V so I expect overload will be unlikely.moamps said:EQ circuitry can be overloaded that way. IMO, better solution is using an unbal/bal output driver.
Maybe not...user 37518 said:Any transformer is more expensive than the 1246/1646 solution.
abbey road d enfer said:Maybe not...
https://www.amazon.com/PAC-SNI-1-Noise-Isolator/dp/B000K50HJE/ref=sr_1_14?dchild=1&keywords=hum+killer&qid=1597906845&sr=8-14
user 37518 said:I stand corrected, what about 2 for $0.41 USD ? https://www.aliexpress.com/item/4000456180096.html?spm=a2g0s.9042311.0.0.58fa4c4dlNBBa2
I've used tons of those to kill hum in conference rooms with small PA's, laptop A/V connections, projectors, etc... Don't even bother measuring THD or freq. response, its better not to know.....
With 0.29H inductance and 135r DCR, they are not really adequate for inputs, just barely acceptable for outputs, provided the stage that drives them has enough oomph and the load is not too hard. It's thetype of fix that should never be left permanent IMO.user 37518 said:I stand corrected, what about 2 for $0.41 USD ? https://www.aliexpress.com/item/4000456180096.html?spm=a2g0s.9042311.0.0.58fa4c4dlNBBa2
I've used tons of those to kill hum in conference rooms with small PA's, laptop A/V connections, projectors, etc... Don't even bother measuring THD or freq. response, its better not to know.....
ruffrecords said:I agree. I do not know why I thought it was impedance balanced.
volker said:That's the EI14 sized one right? The number gives the long side of the lamination in millimeters.
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