Boost output for 220 ohm headphone.

[wirewiggler]

I have a presonus 24c audio interface and Beyer dynamic 770 pro 250 ohm headphones ( got a deal on them or would have gone 80 ohm). The output on the audio interface is not capable of driving the headphone to high levels. Can a headphone amp be added inline to the headphone out to boost the level?

Thanks
Bill

 

[xrk971]

Yes, that’s what headphone amps do. You want one capable of higher voltage swings vs higher current as you have higher impedance cans. Many choices available. Do you want a ready made solution or a DIY one?

 

[duncan2]

An audio interface is basically an external sound card which then depends on the quality and the price as to what output chips it has .


That being so I don't see why you cant buffer the output with a good quality headphone amplifier as long as the output isn't loaded with too low an input impedance .


My expensive audio card (internal ) connects straight onto the input of an old Arcam audio amplifier and sounds great.


I have built plenty of buffers to interface with other audio equipment its no big deal.

 

[wirewiggler]

I was concerned with driving the headphone amp from the headphone output of the audio interface. I would prefer something diy. I have OPC wire se-se headphone amp Board laying about I had not built up. It shows output of 1.9v would they work for this.

The Wire - All Boards and Kits Explained Here!

Thanks Bill

 

[wirewiggler]

This is the headphone out spec of the Audi interface card.
Headphone Outputs
Maximum Power 47 mW / channel @ 56Ω
Frequency Response 20 Hz – 20 kHz (±0.5 dBu, unity gain, unwtd)
Dynamic Range 83 dB (A-wtd, 56Ω load)
THD + N 0.01% (1 kHz, 0 dBFS, loaded)
Impedance Working Range 32Ω to 300Ω

 

[Rick PA Stadel]

The 1,9V amp you mentioned would only be about 1,37dB louder than the 47mW across 56 ohms, which is 1,622V. Don't know about you, but I wouldn't spend the time and effort building something for a decibel and a half.

There should be a good assortment of projects/solutions capable of delivering 4 or 5V across 250 ohms. 5V would be about 9,5dB more than the 47mW you have. 250 ohms is a fairly easy load.

Cheers

 

[dreamth]

You can go safely with the classic NJM4556 op-amp with a gain of 5x...20x.Before trying anything fancy build this one and i can bet you'll really like the sound on 250 ohms cans.I have the dt880pro and i discovered this small pre in a yamaha cassette deck while monitoring some cd player...it sounds better than the usual noninverting topology with the same chip.

 

[dreamth]

if you try the usual noinverting version, try this one as it carries some small good secrets of njm4556 based preamps that no other noinverting one has in it:

 

[dreamth]

If you wanna try something out of the ordinary try this one.You can use different op-amps for the input and output op-amps and you can also use two in parallel (one full dual can like lm6172) for the output section with a 100 ohms resistor in front of each one.Both sections of LM6172 in parallel per channel will give you the possibility to drive 32 ohms cans with +-5 v supply

 

[sgrossklass]

This review has detailed headphone output measurements. The unit seems to be largely voltage limited, delivering 2.01 Vrms into 300 ohms and 1.88 Vrms into 150 ohms.

This seems like a good opportunity to use the Wire SE-SE board in a new build. You'll want a gain of about 6x (15 dB) to max out the 11 Vrms it can deliver.

If you're impatient, something like a JDS Labs Atom should do the job fine as well.

 

[wirewiggler]

Thanks guys, your info has been quite helpful.I may just bite the bullet and return them and buy the 80 ohm version. I got a open box deal on Amazon and they looked like new so I suspect the previous purchaser had the same issue. The review of the 24c was informative if this had been another interface it probably would not have been an issue.

Bill

 

[dreamth]

250 ohms cans sound very well though...you just need a max 4v output preamp...make any of the njm4556 circuits first...it's a 2...3 hours work honestly...I have the DT880pro and i tried all the circuits i posted on them.