Subject: Re: [AUDITORY] What amplifier should I buy to drive Etymotic ER1 / ER2 insert earphones? From: "Nathaniel T. Greene, PhD" <nathaniel.t.greene@xxxxxxxx> Date: Tue, 20 Feb 2018 10:05:05 -0700 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>Our group recently had a conversation with Etymotic about just this = issue, and recommended a few options:=20 Apparently several groups use a TDT HB7 headphone buffer. "Our engineers use the Stewart Audio PA-50B: = https://www.markertek.com/product/pa50b/stewart-audio-pa-50b-2-channel-ha= lf-rack-amplifier-25w-x-2-at-8-ohm They like it because it has a = screwdriver setting for gain, so you can set it and not worry about it = being changed inadvertently.=20 From one of our engineers: Most stereo audio amplifiers will work since they are designed to drive = 8 ohm loads or less. The biggest problem most run into is that they can = easily melt the ER-2 if the volume control is set too high. = We=E2=80=99ve seen many ER-2=E2=80=99s that have been hooked to Crown = amplifiers where the volume control accidently was adjusted and = delivered all 100 watts of output to the poor ER-2. That=E2=80=99s one = reason we like the screwdriver gain controls on the Stewart amplifier.=20 Users can use the small 100 ohm resistors we provide to wire in series = as a fuse, or can make sure their amplifier=E2=80=99s gain can=E2=80=99t = overdrive the ER-2 through other means. Since most amplifiers = aren=E2=80=99t set up for unity gain, we use a 20dB attenuator out of = our PC D/A card to the amplifier input, and then calibrate the gain on = the Stewart amplifier to 20dB, giving a net unity gain.=20 The 100 ohm series resistor we provide will provide attenuation on the = output side of the amplifier, and cut back on the requirements of the = amplifier. The user will have to calibrate their system so they know = their drive levels to the transducer. " "Output impedance is 0.3W and it=E2=80=99ll output nearly 7V at 16 ohms. = $99 dollars each. The question is whether or not you can feel comfortable recommending an = amp from a company called =E2=80=9CSchiit Audio.=E2=80=9D http://www.schiit.com/products/magni-3 Magni 3 - Schiit Audio, Headphone = amps and DACs made in USA. www.schiit.com Magni 3 includes preamp outputs. This means you can connect it to your = desktop powered monitors for a complete system=E2=80=94or even connect = it to a speaker power amp and ... Even though this is a really stupidly named company, the guy behind this = has been doing high-end audio design for a long time, previously = designing for Theta Digital and Angstrom. I=E2=80=99ve seen them in = person and they seem to be built decently for the money." Nate Greene -----Original Message----- From: AUDITORY - Research in Auditory Perception = [mailto:AUDITORY@xxxxxxxx On Behalf Of Bj=C3=B6rn Herrmann Sent: Monday, February 19, 2018 1:29 PM To: AUDITORY@xxxxxxxx Subject: [AUDITORY] What amplifier should I buy to drive Etymotic ER1 / = ER2 insert earphones? Dear list, I have thus far used headphones for my auditory experiments, but a new = experiment I am setting up requires that I use our Etymotic ER1 / ER2 = insert earphones. However, the sounds (played through a Focusrite 2i4 = sound card) are not loud enough (limiting the range of intensities = available). I thus would like to buy an amplifier, but also hope for = reasonable costs. What kind of amplifier would you recommend to drive Etymotic ER1 / ER2 = insert earphones? Thank you in advance for any input you may have. Bjorn ---------- Bj=C3=B6rn Herrmann (PhD) Brain and Mind Institute The University of Western Ontario London, Ontario N6A 5B7 Canada email: herrmann.b@xxxxxxxx web: www.bjornherrmann.com