Comments on: Headphones and Mikes

By: Strangely

Strangely — Wed, 11 Jul 2007 03:03:22 +0000

I’ve looked at an AKG tube and it seems okay but too much dosh for me. Apart from that, I’ve a built-in caution for anything including valves as I got a really bad shock from a valve radio when I was 14. The main advantages of a valve as an amp are the exceedingly high input impedance which doesn’t load the source (like plugging a bass guitar into a valve amp, there’s no string dampening from the amp. This is because the input is the grid in the valve which sits in a vacuum (hence the name) and electricity doesn’t go very well in a vacuum which is the definition of high impedance. Overloading the valve input produces even harmonics which sound nice to the ear unlike the odd ones. ( If you want to know where these terms come from you’ll have to look up Fourier Analysis. Fourier was a French mathematician bloke around about the time of the French Revolution, I think.). This comes from the motion of electrons in the vacuum, but I’ve forgotten how! Under overload conditions, the valve doesn’t get thermal runaway like a silicon counterpart might. The disadvantages are the extra (high voltage and cathode heater) power supplies needed, the fragility of the valve, the valve wears out (as electrons boil off the cathode) and needs replacing frequently, the large size compared to semiconductor equivalents(the biggest valve in common use is the old fashioned TV screen!), the high voltage is dangerous when servicing.

By: Strangely

Strangely — Wed, 11 Jul 2007 02:26:41 +0000

The 990 pros should be more accurate than the 250′s as they are open back. The impedance is 250ohms so they will appear quiet to an amp designed to pump into 60ohm load say. But they are really flat which is what you want, with a really wide freq response. They may not be too good when recording a vocalist alone though as there will be bleed-thru onto the mike because of the open construction. Your 250′s could do for that as Beyer say they are for studio playbacks and intercoms but the response is 10-30,000Hz which seems a bit over the top for that.

By: paul

paul — Wed, 11 Jul 2007 00:40:47 +0000

Forgot to say, I have a pair of AKG 301s too. But I dont like them as there seems to be a lift in the bass region and they definetely dont seem too accurate across the board
:)

By: Strangely

Strangely — Tue, 10 Jul 2007 23:56:41 +0000

The SE looks good but is pricey. Most of the time I don’t think the switched pattern would be of use. This is a dump of the SE and a rode nt1 next to each other, but the rode is a third of the price. You’ll see that the rode also has really low noise output and greater sensitivity. This means to get a given electrical output from a quiet sound, the RODE gives more with less background hiss. They both claim to have a warm sound etc with similar specs in other respects. Have a look at the Beyer ribbon mikes like the M88, M160, M260 which are all excellent at acoustics, vocals AND bass drum of all things!
I’ll have a look at some AKGs next. The AKG 171 looked okay as a headphone, spec-wise as did the Beyer DT990 pro and you won’t get as deaf as with the Sennheiser you bought!

Rees

By: paul

paul — Tue, 10 Jul 2007 23:48:36 +0000

Exactly, or a sine sweep from 20hz – 20 khz, this will better capture the full range of frequencies. You can take impulses of all kinds of equipment too. Like pre amp, compressors, eq and even tape Paul&lt

By: Strangely

Strangely — Tue, 10 Jul 2007 23:39:49 +0000

So I suppose a good way to get it would be to let off a starting
pistol in a church while recording the sound with a good omni-mike and
then chop the bang off the front so you've just got the echoes and
then stick that through your processor so that the dsp chip thingy
emulates it.

Rees

By: paul

paul — Tue, 10 Jul 2007 23:34:35 +0000

Its basically the sonic imprint of the reverberation of a space(ie
church or hallway). With a piece of software you can then use it as
reverb effect on a sound. It then sound like the sound was recorded in
that space. It has to do with the frequencies in that space. If they
are multiplied, not reflected etc etc Pau lo fi

By: Strangely

Strangely — Tue, 10 Jul 2007 23:00:30 +0000

I don't know what you mean by the term "impulse response". What's it
to do with.

Yours Lo-Fi-ly

Rees

By: paul

paul — Tue, 10 Jul 2007 22:52:12 +0000

Cool. I was thinking about doing something with piezzo pick-ups. But
once again wouldnt know where to start. Also if you see any cheap reel
to reel recorders or drum sets(kick, snare, hi-hat)for a bout £40 let
me know. Also are you familiar with impulse responses? Because of
these Im looking for a portable cassette recorder with a built in
stereo mic. I bought a Hi MD minidisc on ebay for £20 which can record
wav's to a 1GB mini disk and I bought for £7 a stereo amplifier with 2
electret mics kit. I have to build it and I also have to make a
balanced connection for it and change the electret mic positioning so
they cross over each other. I want the cassette recorder fo that lo fi
sound All fun stuff Paul

By: Strangely

Strangely — Tue, 10 Jul 2007 22:20:10 +0000

Thanks for that Paul. I'll have a look as I'm much better with
plots and figures than manuf. brochures! However, making a mic
element is a different kettle of fish - especially ribbon ones.
They are put together by people wearing fully enclosed suits so
that there's no dust to drop in the magnetic gap and also so that
the person doesn't breathe on the ribbon, which would snap or
crumple in the teeniest gust of air!

Funnily enough, the guitarist in my old band worked for a time in
Rock City, Newcastle which is a music shop, but he worked in the workshop,
usually fixing ac30s and marshall amps which was usually a new valve
and a squirt of servisol! However, he did "aquire" a box of shure mike
elements, mainly smIIIs and Ivs. All we did was solder some wires,
stick them into bog roll inners and then the whole drum kit was really
cheaply miked up! We couldn't use them for vocals though as there were
no pop filters or grilles or anything, but it was great on the drums;
I had them everywhere!

Rees