Headphone Out on Model 12

Mark Nicholson

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Model 12
Hi,

I have just bought a pair of Bayer DT770 Pro headphones with 250 Ohm output impedance. I have them plugged into the Phones 2 output on the Model 12. They work well, but the sound level is pretty quiet. I have the output cranked the whole way, and they never get more than an adequate level of output.

Is there any way to further boost the headphone output from the board itself? I'm happy with where I have the input signals themselves and the overall metering is fine, but the phones are a little quiet
 
The Beyerdynamic DT-770 Pro comes in several impedances: 32 Ohm, 80 Ohm and 250 Ohm. This makes a crucial difference in how loud they will be on certain outputs: generally, the lower impedance, the louder the headphone.. So if you can, try changing it out for one of the other types (unless you have other reasons for selecting the 250 Ohm version).

Disclaimer: I have no knowledge of the headphone outputs of the Model 12, so there could also be another way for you to get them to sound louder.
 
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External headphone amplifier. But, what @Arjan P says.
 
Agree with Arjan and mj. Your model 12 headphone circuit doesn't have enough audio power to drive the 250 Ohm Beyerdynamic DT770 properly.

However, studying the Model 12 Block Diagram, I don't see a way to incorporate an outboard headphone amplifier directly with the headphone monitor circuit, since there are no parallel line-out jacks associated with that circuit (the headphone jacks are low impedance and not suitable because the inputs on a headphone amplifier are high impedance).

From the Block Diagram, it looks like your possible options for using an outboard headphone amplifier with the Model 12 directly would be to make use of one of the auxiliary circuits or the Sub-out circuit. I don't have hands-on familiarity with the Model 12, so someone else will need to confirm whether either of those is a viable option.

As Arjan suggested, you might want to see if you can exchange the 250 Ohm DT770 for the 32 Ohm or 80 Ohm version. Another option would be the SONY-V6 or MDR 7506, which are much better suited to the task of spoken word projects, IMO.
 
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A Monitor Controller with headphone output should serve well on the output section. It would allow the user to keep the output level constant and have full control over the monitoring.
 
Disclaimer: I have no knowledge of the headphone outputs of the Model 12, so there could also be another way for you to get them to sound louder.
Manual Specifications for Phones jacks (p. 74) is 45mW + 45mW (32 Ohm load)
 
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Geez I have the Beyer Dynamic 990 250 ohm “pro” and it gets plenty loud... I haven’t had the headphone volume knob on the Model 12 up over half with main meter averaging -2db, with 3 dB peak.
 
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Yes, at 250 Ohms, the volume may be there, but the reason I say it's underpowered is that to take full advantage of the 250 Ohm headphone's capabilities as a reference can requires a proper match of impedance to voltage (Vrms) rather than to power (mW).

Generally, to achieve the same Sound Pressure Level (SPL):
32 Ohm headphones require more power (mW)
250 Ohm headphones require more voltage (Vrms)​

Compare the specs for the 32 Ohm and 250 Ohm versions of the Beyerdynamic DT 880 Pro:
32 Ohm: Power/Volts Needed for 90dB SPL: 0.49 mW / 0.125 Vrms (more power)
250 Ohm: Power/Volts Needed for 90dB SPL: 0.36 mW / 0.299 Vrms (more voltage)​
The technical reasons are beyond the scope of this forum.

250 Ohm headphones are not efficient when driven with insufficient voltage. However, when driven properly, the sound stage really opens up (width, depth, detail), precise imaging and placement improves, individual instruments resolve more clearly, etc.

Basics explained here and here.
 
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Hello everybody, I'm thinking of buying the Beyerdynamic DT 880 PRO to use them with my Model 12. To get the headphones working closer to their full potential, I was thinking of using the Sub output instead of the headphones output, as Mark Richards suggested. However, I was planning on doing it without a headphone amp, just plugging the DT 880 with a splitter cable to the Sub outputs. So I'd like to ask you a couple of questions in case you can orient me:

1) Will the option of using a splitter cable instead of a headphone amp work well? As long as the cable is not bad, will it affect some way the listening quality?

2) Regarding connectivity, and as the Sub outputs are balanced ones, my idea was using a splitter cable consisting of a female stereo 1/4" jack and 2 male TRS 1/4" jacks; however, I've only found cables with male TS jacks instead of TRS, so I can only get an unbalanced connection. If I was using external monitors, having a balanced connection would be more important to preserve the signal strength going through the cable and to avoid possible noise issues, but, using headphones, I don't know if the risk of noise entering the listening path can still be high, or if it's improbable enough that I can dismiss it
 
@Bambi sorry, you need an amplifier to drive headphones.
 
Hello MJK, ok. Thank you for the info. Beyond impedance, I forgot to consider the different output and input levels of both devices
 
Headphone amps are as cheap as $20. If you record with others, buy a 4 output amp,so each can adjust their volume as they wish, Behringer have this one around $40 that is surprisingly good.
Behringer | Product | HA400
 
Hello BazzBass, thank you for your suggestion. The Behringer HA400 seems nice. I have one doubt, though. If I use a headphone amp, besides getting more volume, I would do it to take full advantage of the sound quality of such a good headphones. So, would the Behringer HA400 preserve or affect the sound quality I'd get from the DT 880 PRO?

Besides, before buying any headphone amp, I'd like to learn how the Model 12 responds to 250 ohm headphones regarding voltage. @Mark Richards, your previous posts are very useful to understand how high impedance headphones, to work at their full potential, depend more of the amplifier voltage specs rather than the power ones. Do you know how can I find/calculate the Model 12 voltage suppliance when 250 ohm headphones are connected, and if it would be enough for the DT 880 PRO? The only data regarding output voltage I found on the Model 12 manual is "Output voltage DC 15V"
 
I couldn't notice any change to the signal coming out of the HA400 as going in. In other words it doesn't 'colour' the sound. I tested it by listening thru the interface's headphone out and the Behringer amp with the same headphones. No noticeable difference.
 
Hello BazzBass, ok. Thank you very much for the feedback. By the moment, I've ordered the headphones. If the Behringer amp doesn't colour the sound, I don't know if it also means that it isn't taking advantage of the full headphone quality available. The amp is inexpensive, so I wouldn't mind buying one to try it, but only if, besides giving me a higher volume, it allowed me to get the DT 880 full listening potential
 
@Bambi Did you try plugging the headphones into the Model 12 headphone jack and seeing how they sound?
 
Hello BazzBass, ok. Thank you very much for the feedback. By the moment, I've ordered the headphones. If the Behringer amp doesn't colour the sound, I don't know if it also means that it isn't taking advantage of the full headphone quality available. The amp is inexpensive, so I wouldn't mind buying one to try it, but only if, besides giving me a higher volume, it allowed me to get the DT 880 full listening potential

you are way overthinking this.

The amp does what an amp does, increases the volume of the incoming signal. 'It doesn't colour the signal' means it doesn't change the EQ of the signal. If your headphones are good you will hear everything that has been recorded.
 
Design engineers spend millions in R&D to develop amplifiers that are devoid of coloration to the best of their ability.
 
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Hello MJK and BazzBass, I haven't received the headphones yet, so haven't been able to try them. My confussion is with the idea Mark Richards commented in a previous post about the 250 ohm headphones gaining in width, depth and detail when driven with the right amount of power and voltage. And my doubt is if my Model 12 by itself will allow me to benefit from that quality nuances, or if I'd need a headphone amp to achieve it
 

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