Audio Buffer XLR Tested by Matt A in his recording studio

I have conducted a number of tests on the XLR buffer, and have prepared 2 CDs (see below) These include several short bass guitar tracks, as that is what I usually play, although I haven’t played much for the last couple of years due to concentrating on sound engineering. I’ve also included some distorted guitar tracks.

SIGNAL PATH

On both CDs I used

Bass:

Rickenbacker 4003 bass….

through JLM TMP8 pre amps (Joe Malone makes his own gear up in Brisbane and has similar principles to yourself. Joe also makes his own op amps but I’m not sure if they use discrete components. His pre amps sound very good. Here’s the link – http:/.jlmaudio.com/TMP8.htm)

Electric Guitar

Fender Squire Strat

through a 10W amp

picked up by a ribbon mic.

CD1

was fed into a Fostex DL2424 hard disk recorder at 24 bits /44.1 k and truncated to 16/44.1k for the cd.

CD2

was recorded on a Yamaha AW16G at 16/44.1k. to match the setup used in making the original track.

The CDs

CD #1

General :

The first CD has short individual instrument tracks, recorded using a click track

The bass guitar pieces are part of a song from the Melbourne band “X” .

Details of tracks and comments:

Track 1:

Setup: Electric bass through mic input to the preamp. No buffer used

Rationale: Due to impedance differences, the bass recorded through a normal mic input has a paucity of tone. Thus I wanted this track as a datum or reference to represent a recording made without a DI Box.

Comment: You’ll hear that this track is “darker” , ie the bass lacks high-mid to treble, and is muddier.

Track 2:

Setup: Electric bass through DI input (1 M ohm impedance) of preamp. No buffer used

Rationale: This is a standard input setup for direct-in bass recording.

Comment: The treble component is preserved, & the tone of the guitar is preserved to some extent.

Track 3:

Setup: Electric bass through DI input (1 M ohm impedance) of preamp. Buffer used between preamp & recorder.

Rationale: What does the buffer do?

Comment: The tone further enhanced. There’s only a subtle difference when listening to the isolated instrument . I played it to a couple of musicians that dropped by. They were able to perceive the difference.

At this stage I thought that this enhancement (demonstrated from track 2 to track 3) would be more pronounced if the buffer were used to record a bass track incorporated in a complete mix of a song.

Track 4:

Setup: Electric bass through DI input, buffer after preamp, then Bybee Quantum Purifiers before the recorder.

Rationale: Just curious. How does the recording sound with both buffer and the

Bybees.

Comment: Even further enhancement of tone. Signal possibly weaker.

Track 5:

Setup: Electric guitar through small amp into ribbon mic/pre amp then recorder . No buffer.

Rationale: Record something through a mic that occupies a different part of the audio spectrum.

Comment: Small amps distorted can sound gutsy.

Track 6:

Setup: Electric guitar through small amp into ribbon mic/pre amp to buffer then recorder

Rationale: Test buffer effect on recorded guitar sound.

Comment: Sounds even gutsier.

Track 7:(combination)

Tracks 5 & 6 together. Track 5 left, track 6 right.

CD #2

The last two tracks are intended to show how the bass, recorded with and without the buffer, sits in a mix. I used a song “Back to the Shore” composed by a friend, Michael Anderson. We recorded it in 2005. I added two new bass lines. I endeavored to keep the differing tracks at the same level, although I had only the peak meters (and my ears) as a gauge.. A high pass filter on the same setting (of around 30Hz) was applied to both tracks.

Track 1: Bass recorded without buffer

Track 2: Bass recorded with buffer

You’ll hear the bass in track 2 cut through better than in track 1, even though they are mixed at the same level. I would usually have to EQ the bass to achieve this result.. This is usually what the more expensive pre amps will do. As the JLM pre amps have such an excellent sound to begin with, it may be that placing the buffer in the signal path.cannot improve them much.

Placing the buffer in the signal path.of the cheaper type of preamp commonly used (eg Behringer) may produce a more marked improvement.

This would be worth testing, which I will do my best to get to before I pack the old Behringer pre amp for the immenent and long-awaited move to Tassie!

Matt A