June 16th, 2013

Microphone Mod: Carvin’s CTM100 via Microphone-Parts.com

Carvin CTM100 Tube Mic

“Like butter in a black silk cocktail dress.”

I have been interested in microphone modification for years and I went so far as to purchase a Oktava-Mod mic and modification a few years back. While Michael Joly’s mod did sound great, I wasn’t satisfied because I hadn’t done the work myself. I have been short a tube microphone so I decided to get a cheap Chinese mic and put some time and effort into improving the sound.

I ended up getting a Carvin CTM100 tube microphone which is actually the same mic as the Apex 460. At the time of this post the mic is selling for $179 + $12 shipping, which is quite a bargain. The package comes with a large plastic foam lined case, a mic bag, a decent shock mount, a multipin XLR and a power supply. Out of the box the mic didn’t sound bad actually. Certainly better than I was expected for $200. Some high frequency boost made the mic sound sibilant and too bright. While the high frequency boost gave the impression of detail, the mid range wasn’t terribly clear. The was a pronounced proximity effect similar to most large diameter cardioids, but a little boomier than normal. I was thinking that the boost was more in the low mids than in the bass frequencies.

The modification kit that I bought was from Microphone-Parts.com. I chose the Apex 460 Mod Kit (not the SG version) and for a new capsule, I chose the RK7 which is a darker, more-colored U-47 style capsule. I like my mics darker. Most people choose the RK-12 which is based on AKG’s CK-12 which is much brighter and airy.

The kit including the new capsule is only $209, which seems like a great deal. The service at Microphone-Parts was great. Email questions were responded to quickly and completely. When I placed my order I received a bunch of updates and then the kit arrived in maybe 2 days tops. I was really impressed.

Everything was in order and the mod came with a really nice full-color booklet with directions. The directions are probably the best part of the mod kit. They are clear, specific, they have great suggestions and great advice. There are detailed instructions for desoldering and for how to properly use a solder-sucker pump. There were no weird tools required. A precision screwdriver (size 0 Phillips) was the most exotic tools required, but there are included in every $3 jewelers screwdriver kit. In the directions, emphasis is made on cleaning the flux off the board and connections afterwards which I admit I rarely do for cables or patchbay soldering. Still I had the solvent and QTips.

There are links on the website and in the text that point you to helpful videos and suggestions for tools and supplies to buy. I was able to do the complete mod and test in a leisurely morning. I was careful and I read the directions several times. I was fortunate to not have any missteps along the way and the mic sounds great!

All of the high frequency yuck is gone, the response seems very smooth and very detailed. The upper mid range is accurate and flattering for my voice and gave it the quality of a late 70’s radio personality mic, but with more detail and depth. A former professor of mine, Dr. William Moylan, was always very adamant about using objective, descriptive and accurate language to describe sound and timbre. Unfortunately, the word that seems the most descriptive to me is ‘silky.’ There is a slight bump around 4k and a slight dip at 8-9k. There seems to be a very slight natural compression to the microphone now. Before the mod, transient detail seemed too obvious, maybe even expanded. By constant the microphone seems to have a bit of natural compression. This might be due to the tube or to the slightly thicker and slower moving membrane. The RK7 is a 6 micron. I can’t say that I know for sure what the original in the CTM100 is. I did take some photos of the original diaphragm to compare it to the new one:

Original CTM100 Capsule

This is the original CTM100 capsule and diaphragm. You can easily see that the diaphragm is NOT flat.

Original CTM100 Capsule

In this angle of the original capsule you can see how much dust is on the surface of the diaphragm. This is a brand new mic, so I am pretty sure that the dust is from the manufacturing process.

Effectively all the sibilant frequencies were diminished to the point that I wouldn’t think about reaching for a de-esser. The proximity response seems more gradual and nuanced. The effect could be easily controlled for some reason and there seemed to be more gradations in the boost compared to distance. Overall, I think that the modded microphone sounds fantastic. It will certainly replace my other vocal mics for my own voice and I suspect that I will reach for this mic when I need to tone down an overly bright female or a sibilant/whistle-prone male vocal.


June 2nd, 2013

Coming Soon: Review of Black Lion Audio’s AGB Stereo Compressor

The Black Lion Audio AGB Stereo Compressor

The Black Lion Audio AGB Stereo Compressor

I have been looking for a new flavor of compressor for a quite a while. I love the ease of use of the LA-2A style optical compressors, the speed and intensity of FET compressors and the predictability and smoothness of the dbx VCA compressors. But I want something new. The AGB is a diode compressor, based on the Neve 33609, so I was looking forward to hearing something new. I am working on an evaluation of Black Lion Audio’s compressor and I will share my findings here.

You can read all about the compressor on Black Lion’s website, but there really aren’t very many reviews out there with any detail so far. So check back here for the review. Also coming soon a review of the Black Lion Auteur Preamp!

February 17th, 2013

Trying Out Pro Tools for the First Time

I should mention that I have been a user of audio software for 20 years and a professional audio engineer for just as long. I have been a PC user for audio and my DAW of choice was first ACID, then Vegas, then Cakewalk’s Sonar. I have been staunchly opposed to the Digidesign “you must use our hardware” policy ever since I learned what Native meant. So I was interested when I heard that starting with version 9, Pro Tools has been compatible with other hardware. Hurray!

So now, Feb 16, 2013, I am trying Pro Tools again…for the first time since M-Powered… So I authorize my iLok with the Demo version of Pro Tools 10 and download the demo version, which is also version 10. I am using Windows 7 SP 1 and 2 MOTU 2408MK3’s. I install Pro Tools and fire it up when I get this error:

WARNING Loss of Plugin Authorization May Occur

WTF? I am starting to remember why I have so afraid of installing this on my DAW machine. I actually use my DAW for stuff, like making money. My C: Drive is called SystemWindows7 which apparently is bad. I tell it to keep going. Pro Tools hangs with the error that the audio interface can’t be adjusted and then pukes.

I verify that Pro Tools is supposed to work with my hardware. I discover that the version I downloaded is 10 and I should have downloaded 10.3.2. Do I download it and try to install it. Puke. You can’t install this version without uninstalling the old version first. So I uninstall it and try to install 10.3.2. I fire it up and get:

DAE Pro Tools Error


Oh yeah, this is awesome software. I try to find some documentation in the install talking about this. Nada. I visit GearSlutz for help on the error. That turned out not to help much. So then I find this:  DAE error 9514; Pro Tools won’t launch (Windows)

The short version of what the suggestion is that there was an install problem where I was using anti-virus during the install. Unfortunately I don’t use anti-virus on my DAW machine, so this isn’t the problem.

I am starting to realize that this isn’t going to be easy. I am several hours into the process and so far the software isn’t even usable. I don’t have a complicated system. I am running a Windows home network with a few machines attached. No domain, just a home group and file sharing. So far I am not impressed at all.

So I try to do an uninstall and I get this:

Cannot remove shortcut.

So it looks like I can’t get even get a clean uninstall to start over from scratch. So I am going to start another post for the next stage of this disaster…or continue with this one.

Now I have reinstalled Pro Tools and the computer won’t boot up. After an hour it does boot up after a full cold boot. I start Pro Tools and try to make a project and I get:

Pro Tools Sample Rate Error

Oh boy. I am going to continue to bang on this for a while until I get it to work. Otherwise I will have to go in to school to grade projects using a Mac and 10.3.2.



November 24th, 2012

DIY Audio Mixing Circuits

For a while now I have been interested in summing in the analog as opposed to the digital domain and I built a 16 channel summing mixer with Daking-style amplifiers. I haven’t been very happy with the usability of summing mixers without linear faders and pan controls. It just doesn’t feel right. If you’re mixing with rotary knobs, you can only turn two knobs at once, but when you mix with faders you can do at least 8 at a time.

I basically started doing some research about the kinds of circuits that I need to build and I wanted to post links to the stuff that I found to be the most helpful.

Simple Mixer Schematics from All Electric Kitchen: http://www.all-electric.com/schematic/simp_mix.htm

Slightly more complex mixer circuits (Pre’s, EQ’s, Line Drivers):  http://www.all-electric.com/b&c.html

Elliott Sound Products (ESP) Article on Audio Mixing: http://sound.westhost.com/articles/audio-mixing.htm

I will add information as I read more!

August 1st, 2011

Introducing the Acoustic Ramp™ Diffuser

As some of you already know, I invented a new type of number-theoretical diffuser a while ago and I have been working on developing it into a product and filing the necessary patent applications.  It’s called the Acoustic Ramp™ because it is wedge shaped.  The diffuser became my master’s thesis for my degree work at the University of Massachusetts in Lowell in Sound Recording Technology.  The degree that I will earn is called a Master’s of Music in Sound Recording Technology (M.M. S.R.T.) and will hopefully make it easier to get a job that pays the bills!

This past Saturday 7/30/2011 I spent the day running a series of tests on the diffuser and comparing its performance to that of a flat reflector.  Essentially what I am trying to show is how much better the back wall of a control room would be if it had an array of my Acoustic Ramp™ diffusers and wasn’t a flat wall.  When sound hits a flat wall it bounces back, a lot like a rubber ball might bounce.  The problem is that the sound bouncing off the wall interferes with the sound going towards the wall and causes problems like comb filtering, flutter echo and bass buildup. One option for handling the problem is to absorb all of the sound hitting the wall and preventing it from reflecting.  This works, but really changes the sound of the room, deadening the frequency response and creating an unnatural ambiance. The other option is to use diffusion to reflect the sound in many directions and to prevent the sound bouncing back in only one direction.

Testing the Acoustic Ramp

Testing the Acoustic Ramp at U. Mass Lowell's Concert Hall

Testing a diffuser is actually pretty complicated and involved, but in a nutshell the process is as follows:

Shoot an impulse burst of sound at the diffuser and then record what bounces back every 5 degrees in the semi-circle around the diffuser.

The white tape in the picture shows the test points where I placed the microphone. The first test point is at 0 degrees directly underneath the speaker.  This test point simulates what a listener might hear if they were sitting directly in front of the speaker and the sound went past them and hit the back wall of the control room and then bounced back.  A flat wall would reflect a sound very similar to what was coming out of the speaker, essentially an echo that hasn’t been greatly changed. A diffuser should have multiple smaller echoes spread out over time with seriously reduced sound pressure. This is what the 0 Degrees test results look like:

Flat Reflector vs. Acoustic Ramp

Diagram showing the difference between sound reflecting of a flat reflector and sound being diffused by the Acoustic Ramp

As you can see from the diagram, the large reflection in the top response is changed into a series of three smaller reflections  and greatly attenuated (reduced) amplitude when diffused by the Acoustic Ramp.  The reflection is spread across time and diminished greatly in amplitude.

Hurray! It Works!

July 17th, 2011

JBL L100T: Speaker or Food Storage?

I was recently given a pair of JBL L100T speakers from the late 80’s.  They needed to have the foam surround replaced because the originals had started to rot away. I ordered new surround from Speaker Works (http://www.speakerworks.com/) so that I wouldn’t have to pay an arm and a leg for the repair.

In order to replace the foam surrounds, I needed to first remove the woofers from the cabinet so that I could work on the speaker more easily.  After removing the speaker, I discovered a large pile of what appeared to be cat food in the bottom corner of the speaker.

Here are some of the photos taken on my phone. Apologies for the poor quality, the room was dark and I had to use a flash for up close photos…

Inside JBL L100T Speaker

Cat food carefully collected and stored by a family of mice.

Underneath the fiber glass absorption...

More cat food and mice dropping found under the fiberglass insulation

Bag full of cat food pulled from speaker cabinet

I pulled the bag's worth of cat food out of the speaker cabinet.

More later when I get the speaker surrounds replaced!


February 6th, 2011

Do You Need A Demo?

When a band or artist is first starting out, many choose to make a demo recording of their music. While some find that recording a demo is essential in getting their musical career off the ground, others find that it has little benefit to them in the long-term. Here are just a few things to consider when thinking about recording a demo.

If you’re a new artist or band, then you might not have the financial backing which is often required to record a whole album, which can require a larger of time to be spent in the studio. Once you have a recording contract, it is also unlikely that your original recording will be used – usually they will be professional rerecorded before public release. In this sense, recording a whole album simply to allow music executives to listen to a short sample can seem like an unproductive use of time and money – it can be a better idea to simply record a short demon to show what you can do.

It is also worth bearing in mind that demo recordings do not always give a true representation of your musical ability. After all, those who like your music won’t simply want to listen to your recordings as they play online games or on their headphones during their commute to work. They’ll also want to hear you play live – and so will record companies and producers. Although the fact that broadband internet is now widely available from companies such as O2 can mean that a large number of people will listen online to digital recordings of your music, this will not negate the need to be able to play live. Whilst a demo can act as a good taster of your sound, but you should make sure you are able to recreate that sound for a live audience should you be invited to.

Lastly, it is worth bearing in mind that unsolicited demo tapes rarely get much attention. Only record a demo if you have a clear plan on how you want to use it – other than just blindly forwarding a copy on to every record company which you can think of. Otherwise you may be better off recording a full album, which you may be able to see at gigs and performances.


November 22nd, 2010

Audio Interfaces and Patchbays Question


I have a question about the patchbays. I’ve laid out all my gear and figured out every I/O that I have and what cables I need, I started hooking things up and I’m slightly confused about how the audio interface (M-Audio Delta 1010) hooks up with the TASCAM DM-3200 through the patchbay.


The most common configuration for an audio interface, a mixer and a patchbay is as follows:

Directs outputs on the mixer would be half-normaled to the analog inputs on the audio interface.

Analog outputs on the audio interface are half-normaled to the line inputs on the mixer to allow for digital mixing in the mixer.

In the case of the TASCAM DM-3200, in order to get more analog outputs you would want to purchase 1 or 2 TASCAM IF-AN/DM 8-channel expander cards.  You would use these additional outputs as direct outputs or bus outputs.  Out of the box, the DM-3200 has only 4 assignable analog outputs, plus the main outs and the monitor outs.  The DM-3200 does have 24 channels of TASCAM Digital Interface outputs (TDIF) and you could buy an audio interface card that has TDIF digital inputs.

You could also purchase the TASCAM IF-FW/DMmkII a card the makes the DM-3200 into an interface eliminating the need for the M-Audio Delta 1010’s.  The only problem with this is that M-Audio has REALLY good drivers for the Delta 1010’s and TASCAM has a really bad reputation for their drivers and support. I have no firsthand knowledge of problems with drivers for the DM-3200, but I have experienced the disaster of Giga-Sampler, Giga-Studio and GVI which all used specialized drivers to work.

Hope this helps!

October 27th, 2010

Classic Gear: Distressor

By Carlton Meriwether (from the New England Institute of Art AKA AI New England)

Distressor EL8-X

Distressor EL8-X

Distressor EL8-X

The Distressor EL8-X is a mono digital compressor/ limiter produced by Empirical Labs. A highly adaptable machine they’re considered one of the industry standards for compression and distortion. They have a multitude of compression ratios ranging from 1:1 to 20:1 and a Nuke setting for brick wall limiting. Two types of distortion can be applied focusing on 2nd or 3rd harmonics.  Time based features like attack and release are calibrated to keep consistency between machines when stereo linking.

The Distressor was built with not only modern compression but with vintage emulation in mind. The Distressor has a soft parabolic knee when set to ratios less than 6:1 giving a more natural sound to compression. Setting the unit to 6:1 or greater applies a more sharp vintage knee to simulate tube, FET, or  optical compressor machines from the past. There are specific settings listed by the manufacturer to emulate the LA-2A, 3A, 4A; the dbx160; the Fairchild IGFET and 670.

With a frequency range of 2Hz to 160kHz and a 110dB dynamic range the Distressor is a complete all around compressor. With an MSRP of $3000 for a pair ($2295 through dealers like SweetWater) the Distressor is a reasonably affordable replacement for multiple vintage compressor/limiter rack modules. An over all well built machine utilizing all metal film and Roeder resistors, the craftsmanship is well above average in American made electronics. The hand connected input and output ports allow for consumer changing of the “hot” pin in the xlr connectors to match any gear already in use and the A/C power source can run on 110 and 220 volt inputs giving the Distressor superior compatibility on a global scale.







October 25th, 2010

Classic Gear: dbx 160

Written by Joe Cenedella (New England Institute of Art AKA A.I. New England)

dbx 160 (1976) Designed by David Blackmer, using early Overeasy circuit and RMS detection

The dbx 160 was introduced in 1976 as a professional quality compressor/limiter.  The brainchild of David E. Blackmer (founder of dbx) it quickly became a must have for studio engineers of the time.  Besides being one of the earliest compressors, the dbx 160 introduced to the market features that allowed for a much smoother and more natural sounding compression.  The 160 uses voltage controlled amplifiers (VCAs) which adjust gain settings to fluctuate with the voltage creating smooth and natural sounding compression that closely simulates how the human ear interprets sound. Along with the VCA the dbx 160 introduced true RMS detection paired with feed forward gain reduction. This allows the model to achieve an infinite compression ratio (120:1) without excessive gain levels, and without excessive distortion, which causes oscillation in the feedback loop. All models of compressors at the time the dbx 160 was introduced gave the user some control over compression in the form of preset ratios (10:1, 20:1). (source) this is where the VCA’s come in allowing the attack and release to fluctuate with the input signals envelope. This allowed for more of a set it and forget it approach instead of constantly adjusting the ratio throughout a performance.

The Features:

Auto detected/attenuated 40dB for ground loop hum

Introduced “over-easy” compression, or soft knee compression

Adjustable threshold 10mV-3V

LEDs for input level, output level, or gain

First to have fully adjustable compression up to 120:1

RMS detection, VCAs, and Feed Forward gain reduction

VU origin adjustable 20dB (+/- 10dB input)

Mono inputs, two required for stereo tracking

Output level of +/- 26dB Hi-Z, +/-24dB Lo-Z

Cost New: $300 in 1976

Cost Now: pair sells on ebay for $1600

Link to user manual: http://mixonline.com/online_extras/dbx_160.pdf

Official dbx Pro Audio Info: http://www.dbxpro.com/vintage_download.php?product=160

Other Sources: