amp, mics, SPLs picture...

[ecc83]

The setup:
Two mics strapped together, £25 dynamic form Maplins (I have donated my SM57 to my son's musical works in France! I know from previous tests that this mic is about 6dB more sensitive than a 57) The other is an AKG Perception 150 set for max sensitivity. I know left from right. Yous all must guess! Both mics are touching the cab fret just off centre of the Greenback, a 55Hz jobbie.

The amplifier I shall also leave unsaid for now.

Mics feed a KA6 the cap' channel is at zero gain and the dymo at 2 0'clock. The clip is being played out of a 2496 card to the amp.
The levels can be seen attached and in fact average around -13dBFS with a 'clang' at -9.5dBFS max. Thus, those with a 57 should not have any problem as levels will be about -19dBFS for the same gain setting and there is gain in hand. A Maplin N33GJ C weighted SPL meter was put against the fret next to the mics and recorded ~102dBC. Out in the room it was set some 1.5mtrs from the centre of the cab 1mtr in the air pointed straight up on a camera stand and read ~85dBC.

 

[keith.rogers]

I preferred the right channel, but they sounded quite good together (split then panned center in Audacity). I'm going to guess right was the AKG, but I have no basis for that other than name bias probably. The left I'd have considered a bit muddy by itself, but either would have been workable.

 

[ecc83]

I preferred the right channel, but they sounded quite good together (split then panned center in Audacity). I'm going to guess right was the AKG, but I have no basis for that other than name bias probably. The left I'd have considered a bit muddy by itself, but either would have been workable.

Thanks Keith. I shall let a few more comments come in before I reveal all! Any ideas on the amp? Make, power, active devices?

I had to post what I did a bit swiftly and then got "Backend fetch failed" whatever TF that is! My main reason for the post was that new peeps seem forever to be having topology problems with their undergarments with levels, gain, noise and DAW signal displays! I hope this offering ties all those things together? I am saying.."Make THIS much noise in a room, stick almost any microphone against the cab and you will get MORE than workable levels with any AI (the KA6 has about 55dB of gain). If you don't, something is wrong and the "system" needs to be gone through in a 'systematic' way.

Ok, noobs will not likely have an SPL meter to hand (but DO get one as soon as your are able. $15, C weighted, easily good enough) so how loud was the amp? My wife was in the next room watching telly, separated by a single wood panelled door. She could hear the amp but was not distracted by it.

Any questions, anything else I can try? Shoot!

Dave.

 

[keith.rogers]

Thanks Keith. I shall let a few more comments come in before I reveal all! Any ideas on the amp? Make, power, active devices?
...

I heard some reverb, so assumed that was an amp 'verb. I really am pretty dumb about the different amp sounds. Well, I know what I like, and it's somewhere between the [older] Vox and Fender families, and this could easily fall in that range, but I've recorded a MicroCube and that's just fine for a lot of things too!

Your post is really good. I might try something like that later if I can get the lawn irrigation probs sorted out, a few lb of sheet music packed up and off to the son, and other household to-do's out of the way! Oh, and remember how to plug in the electric guitar...

 

[ecc83]

'Verb on the signal K? Sorrry, red fish, did not intend that. The clip was done by son quite few years ago (I have others but mainly jazz or classical and I wanted rock ) and he did several for me for a purpose no longer valid, some I re did with a reverb pluggin. Would perhaps have been better to use a dry clip but twas done before I realized it.

Have to say, sitting next to a cab chucking out 102dB SPL makes me realize just how bloody deaf I have become!

Dave.

 

[ecc83]

The right hand mic was the crap dymo, so crap I think that I shall rig another test with my shiny new Prodipe TT1.

No one had a stab at the amp? Thought some of you might GUESS it was a Blackstar! HT-20 (EL34, FIXED and cathode bias. Some solid state bits in the signal path) Driving, as I said, a Greenback in a modified HiWatt combo cab (W570 H450 D270mm)

Dave.

 

[jamesperrett]

The right hand mic was the crap dymo, so crap I think that I shall rig another test with my shiny new Prodipe TT1.

Try moving the mics a bit further away from the centre of the cone - you may find the preferences reversed. You probably already know that my favourite guitar mic was never intended to be used as a mic. It is a Sennheiser HD400 (but I'll blame Mike Skeet for the original idea).

 

[ecc83]

Try moving the mics a bit further away from the centre of the cone - you may find the preferences reversed. You probably already know that my favourite guitar mic was never intended to be used as a mic. It is a Sennheiser HD400 (but I'll blame Mike Skeet for the original idea).

The mics were "stacked" James, one above the other on about a 25mm centre so the were both in the same vertical plane of the cone. The dymo just sounded 'dull' to me.

The exercise was not intended to give a definitive 'super tone', more to show the sort of levels you get in a DAW for a known SPL at the cone and in the room.....SO many people seem to get in mess with this?

Will do the French job in a few hours, must pit now!

Dave.

 

[ecc83]

"Sennheiser HD400 " Just gets me headphones?

Dave.

 

[Mickster]

"Sennheiser HD400 " Just gets me headphones?

Dave.

Wacky......I know.........but lots of headphones can be used as a mic..........normally not with good results...........but essentially they can work as a mic. When I was young........back before the wheel.......I remember plugging in a set of headphones into the mic jack of a cassette recorder. With the input fader pushed all the way.......I could record. Just my 2 cents.

 

[arcaxis]

Similar to using headphones as a 'mic', way, way back in my teen years I had played around using a speaker hooked up through a vacuum tube output transformer to step up the impedance as a 'mic'. It worked, but not well as could be expected.

 

[ashcat_lt]

I learned about headphones as a mic from rave DJs in the 90s. Apparently it's a pretty standard trick since they've almost always got the cans, but very often "forget" the mic. I've heard they can work well for upright bass.

Speakers as mics (well, headphones ARE speakers), but people have been doing that for years too. Most common usage is as a "sub kick" mic to get the ultra low thump. In fact there are a number of companies out there building them with nice mounting hardware and everything.

 

[ecc83]

Wacky......I know.........but lots of headphones can be used as a mic..........normally not with good results...........but essentially they can work as a mic. When I was young........back before the wheel.......I remember plugging in a set of headphones into the mic jack of a cassette recorder. With the input fader pushed all the way.......I could record. Just my 2 cents.

Not in the least wacky! Basic electro-magnetics. The loudspeaker as a kick mic is almost standard kit in many studios I believe?

But...to the chase? Typo methinks James?

Dave.

 

[ashcat_lt]

What's even more fun is that Dynamic mics are also speakers! I had an ART Dual MP for a while and didn't realize that the Instrument and Mic inputs were literally just parallel connected via straight wire until I was playing my guitar standing next to a mic I didn't think I was using and heard the guitar coming out.

 

[Gtoboy]

I know its off topic but for wackiness : output a track or mix through headphones or any speaker small enough to fit in your hand(even use a dyn mic as a "speaker") and play back through a live amped electric guitar pickup , record the output from the amp. The guitar and amp tone controls ,volume ,distortion , various pedals, and the guitar itself can be utilized to manipulate the sound coming from the amp and you can come up with some crazy stuff. I have a fondness for "playing"" rf remotes(TV, DVD Player, etc) through guitar pickups too.

 

[keith.rogers]

At the risk of putting this onto a parallel set of rails, but perhaps going in a similar direction as the original, I plugged in the electric (first time since last July maybe) and tried to make my fingers stay on the strings for a few minutes.

One dynamic and one small, side address condenser, placed as near as possibly in the same location on opposite sides of the cone, about an inch and a smidge in from the edge, and an inch or so off the grill. Recorded in Audacity. There's no test here, because the picture will tell the tale if nothing else.

First, it was set pretty low volume, measuring on my "super accurate" phone app about 100-102dB a couple inches in front of the speaker, and pushing 90 where I was sitting. Just adjusted the gains until the interface LEDs looked to be bouncing around the same and the waveforms (quite visible) in Audacity looked as close as possible. Now, while I had to push the dynamic gain quite a bit higher, it was still below where I'd feel like I needed to go looking for a preamp. (And, realistically, the amp was practically quiet compared to most electric guitar recording.)



Recorded as stereo, but if I wanted to use this idea, I'd probably just mix these mono, or maybe with a little pan. The clear takeaway, both in listening (split to mono in Audacity to compare best IMO) is that the dynamic has a little bit of natural compression, and even though the distances were the same, a lot more proximity effect. Enough that I won't ever put it that close to the grill again.

The condenser peaks about -7dB and dynamic about -9, but the integrated LUFS for the dynamic is 0.3dB louder than the condenser. It had few dB more low rumble at the end but I think that was just the proximity effect, and not really more noise. The setup wasn't going to prevent that as the amp and both mics on short stands were on the same table!

Dropbox - t2mictest.wav (apologies to all electric guitarists out there!)

 

[SAM CA]

...I remember plugging in a set of headphones into the mic jack of a cassette recorder. With the input fader pushed all the way.......I could record. Just my 2 cents.

ha ha ha...believe it or not this technique is still being used even in "ProAudio Events" such as the one I just attended this past weekend in SAE Institute! So Native Instruments had a clinic on basic mixing with Traktor S8. Guess what? They forgot to set up or even bring a mic for the speaker, so she had to use a headphone! Here's the proof:

In The Mix Reviews on Instagram: “#imstafesta #imstafesta2018 #imstafestalosangeles #celebrationofmusictechnology #saeinstitute #saelosangeles #buythesoftwareyouuse #ni…”

She made that gesture for fun...but that's how it went down till someone brought an SM7B mic but no mic stand. It was very awkward but fun.