recallmenot
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- Apr 5, 2024
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Hi, y'all!
So yesterday, inspired by the ifi Ear Buddy review, I've tried to finally connect my IEMs (Truthear Nova) to my audio interface (Fireface 800).
The Fireface does have an excellent headphone output, but it's optimized for low-impedance, high-impedance headphones (240-600 Ohm), with IEMs it's way, way too loud and the noise floor is too present, regardless of set volume.
Furthermore, the impedance mismatch (just 15 Ohms for the IEMs) would lead to funky sound since
AND on top of that, we're dealing with a 1DD+4BA driver setup with passive crossovers, so the impedance curve is funky as-is.
Luckily, with a simple resistor voltage divider, we can apparently sacrifice a lot of output power to gain lower output impedance while simultaneously pushing the noise floor back down where we can't hear it any more.
If that's really all there is to an iFi Ear Buddy / iEMatch+ ... still haven't seen the insides of either.
The schematic:
The resistor values:
R1, R3 = 12 Ohm +- 0.15 Ohm
R2, R4 = 1 Ohm +- 0.02 Ohm
Note the tight tolerances!
We want to stay below 0.5 dB channel imbalance (which would already be easily detectable as the sound not coming from dead-center).
If you're going to use cheap 1% metal film resistors, you'll need to match them as closely as possible, requiring a very precise multimeter and good test leads (I have some with crocodile clips).
Though it might be easier to just order the 0.01% or even 0.001% Resistors instead of sorting through ~20 to find one close pair, each time waiting 30 seconds+ for the multimeter's noise filtering on the resistance measurement to stabilize.
Those resistor values give us a ~1 Ohm output and whack the sound (and thus noise) by around -22 dB.
If your amp has that headroom, then you can try this!
The cable I built has them soldered as shown, but basically as an "in-line" part of the cable.
I just used a regular old 3.5mm extension cable and clipped it in the middle and put the resistors in-between.
I made an extended GND connection so the resistors have place in there, arranged in a V-shape.
All that isolated with multiple layers of heatshrink.
You'll have to drive the cable hard to get an acceptable volume out of the IEMs but oh man is it worth it!
I'm hearing just what I'm hearing from my DT880s through the interface: heavy but precisely controlled lows, it feels dark yet clear, clean and smooth.
Mind you, I'm not listening to the IEMs without EQ: To me, the Harman target is garboleum, DF5128 (or Etymotic) is so much better.
So for me it worked, for you it might too!
So yesterday, inspired by the ifi Ear Buddy review, I've tried to finally connect my IEMs (Truthear Nova) to my audio interface (Fireface 800).
The Fireface does have an excellent headphone output, but it's optimized for low-impedance, high-impedance headphones (240-600 Ohm), with IEMs it's way, way too loud and the noise floor is too present, regardless of set volume.
Furthermore, the impedance mismatch (just 15 Ohms for the IEMs) would lead to funky sound since
Code:
Zamp_max = 1/8 * ZdriverLuckily, with a simple resistor voltage divider, we can apparently sacrifice a lot of output power to gain lower output impedance while simultaneously pushing the noise floor back down where we can't hear it any more.
If that's really all there is to an iFi Ear Buddy / iEMatch+ ... still haven't seen the insides of either.
The schematic:
Code:
source target
Tip (Left) ----------- R1 --+-----------> IEM Left Tip
|
R2
|
Sleeve ----------------------+-----------> IEM Sleeve (common ground)
|
R4
|
Ring (Right) ---------- R3 --+-----------> IEM Right TipThe resistor values:
R1, R3 = 12 Ohm +- 0.15 Ohm
R2, R4 = 1 Ohm +- 0.02 Ohm
Note the tight tolerances!
We want to stay below 0.5 dB channel imbalance (which would already be easily detectable as the sound not coming from dead-center).
If you're going to use cheap 1% metal film resistors, you'll need to match them as closely as possible, requiring a very precise multimeter and good test leads (I have some with crocodile clips).
Though it might be easier to just order the 0.01% or even 0.001% Resistors instead of sorting through ~20 to find one close pair, each time waiting 30 seconds+ for the multimeter's noise filtering on the resistance measurement to stabilize.
Those resistor values give us a ~1 Ohm output and whack the sound (and thus noise) by around -22 dB.
If your amp has that headroom, then you can try this!
The cable I built has them soldered as shown, but basically as an "in-line" part of the cable.
I just used a regular old 3.5mm extension cable and clipped it in the middle and put the resistors in-between.
I made an extended GND connection so the resistors have place in there, arranged in a V-shape.
All that isolated with multiple layers of heatshrink.
You'll have to drive the cable hard to get an acceptable volume out of the IEMs but oh man is it worth it!
I'm hearing just what I'm hearing from my DT880s through the interface: heavy but precisely controlled lows, it feels dark yet clear, clean and smooth.
Mind you, I'm not listening to the IEMs without EQ: To me, the Harman target is garboleum, DF5128 (or Etymotic) is so much better.
So for me it worked, for you it might too!
