Test Drive: 4 ProMods from Ramko Research

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by Jerry Vigil

This month's Test Drive is perhaps the simplest yet, in terms of how complex the gear is. The equipment under inspection has no pretty LCD display. There aren't any knobs or buttons. You can't do fancy, digital cut and paste editing with it, and everything fits into a box roughly the size of a pack of cigarettes. Introducing, the ProMod Ultra Miniature Modules from Ramko Research.

Ramko has been around for a while, but these little boxes are relatively new to our industry. You may have spotted one stuck to the side of an equipment rack somewhere in your station and didn't give a second thought as to what it was. Ramko offers over fifty modules to choose from, each handling a unique task, anything from compression and EQ to mixing and amplification. Aside from their compact size and simplicity, another attractive facet of these modules is the cost. Prices range from about $45 to $160 per module depending upon the type and quantity purchased.

Checking out all fifty-plus modules would be fun, but maybe a little monotonous. So we picked four that we thought might pique your interest.

The P-1ACL Line Input Audio Compressor/Limiter

Connections to the ProMods are made with a wire captive terminal block with twelve connect points. Some modules use more points than others. The modules are powered with external 12 volt AC adaptors which connect to the first two connectors. On the P-1ACL, the next three connectors accommodate balanced or unbalanced output, and connectors 6, 7, and 8 are for balanced or unbalanced input. Connectors 9 through 12 are unused. As mentioned, there are no knobs, but keep your little screwdriver handy. There are three adjustments for this compressor/limiter. Three holes on the top of the metal housing access Gain Adjust, Compression Ratio Adjust, and Compression Threshold Adjust. The Gain is adjustable from 0dB to +23dB. The Compression Ratio is adjustable from 2:1 to 5:1, and the Threshold can be set from +10 to +22.

Granted, you don't get the controls found on high dollar compressor/limiters, but the P-1ACL isn't trying to compete with those boxes. Instead, the P-1ACL is a low cost method of handling simple compression/limiting tasks without taking up a slot in your equipment rack. Where would you use a little box like this? How many people in your station use a microphone in one of your studios, but have no idea how to use the mic processor in the same room? How many times do you get voice tracks from people who fail to properly watch their levels? A simple compressor/limiter like the P-1ACL is ideal for little fixes like this. You can install it permanently in line, hide it in a nearby cabinet, set it, and leave it alone. Apply just enough compression to assist those who like to overmodulate just a little too much. Add just enough punch to voice tracks that otherwise might go unprocessed altogether. The P-1ACL also works well on phone lines in control rooms to help keep recording levels between callers and jocks under control.

These are just a couple of applications for this single channel compressor/limiter. Of course, you could get two units to create a stereo compressor/limiter if desired, just remember that settings to the left and right channels have to be made independent of each other. Reported specs on the P-1ACL include a frequency response of 10Hz to 60kHz. Output is +24dBm into balanced 600 ohms, +20 into unbalanced 600 ohms. Distortion is rated at 0.007% without compression and 0.09% at full compression. Noise+hum+distortion is at -80dB. The unadjustable attack time is at 5 ms. The release time is compression depth dependent. List price on the P-1ACL is $119.


P-3EQ/L High Performance Line Level 3-band Equalizer

And while we're on the subject of putting a compressor on line with your mics, why not add some EQ as well? The P-3EQ/L is ideal for quick and dirty EQ tasks. Again, the first two connectors on the terminal block are for the 12 volt AC power, and connectors 3 through 8 provide input and output. Each module also provides a ground lug on the metal housing for RF and hum shielding. Three holes in the metal housing access three controls for adjusting the Low, Mid, and High EQ boost or cut. You get 18dB of boost or cut. The bandwidths are broad and unadjustable. The center frequencies are at 20Hz, 1kHz, and 15kHz. The high frequency adjust affects just the right range of frequencies to add crispness to voice tracks or dull music tracks. The low frequency control also affects the voice nicely if you want to add some "boom" to your voice. For my personal tastes, a higher center frequency on the mid-range control would have been more useful for tweaking telephone audio or for giving your voice that "telephone EQ" effect. Aside from that, if you're looking for simple, inexpensive EQ, for voice or music, particularly if you want to set it and leave it, this little box is for you.

Other uses in radio might include several in the on-air studio to brighten incoming lines such as traffic reports, network feeds, and remote broadcast audio. If the on-air studio mics don't have any processing on them, the P-3EQ/L along with the P-1ACL compressor/limiter make a nice pair and are certainly better than no processing at all, especially in an environment where tweak-happy DJs are discouraged from messing with settings for such things.

Specs on the P-3EQ/L include a flat response from 10Hz to 50kHz, and noise at -85dB. Noise+hum+distortion is at -77dB. The P-3EQ/L lists for $75, but Ramko offers sale prices and discounts for purchasing more than one box. Ramko offers three 3-band equalizers. The P-3EQ/L provides line level in and out. The P-3EQ/M has a mic level input and line level out. The P-3EQM/M is mic level in and out.

The P-2IA Dual Input Audio Interface Amplifier

Here's a handy little box for production studios, mainly because we use so much "consumer" and "semi-pro" equipment, from effects boxes to CD players and cassette decks. The P-2IA converts signals from balanced to unbalanced or from unbalanced to balanced. There are two inputs and two outputs. Gain controls at each output are accessed through two of the three holes in the metal housing. (The other hole is unused.) The gain is adjustable from -1dB to +22dB. The ins and outs are at line level. Frequency response is 10Hz to 70kHz. Noise is at a low -92dB. Noise+hum+distortion is at -89dB.

As with the other modules, the small size of the P-2IA lets you tuck it away nicely inside your equipment rack. Each module also comes with two adhesive Velcro strips. You can stick it anywhere inside an equipment rack, or even attach it to the gear itself. The P-2IA interface amp lists for $116.

The P-ACR/L 100 Silence Sensing Audio Relay

Our last stop on the ProMod tour is the P-ACR/L 100. What do you need a silence sensing relay for? Okay, this might not be the kind of toy you shop for when thumbing through a catalog of studio gear, but chances are your engineer has one operating somewhere at your station, if not several places. If your station (or sister station down the hall) is automated, a silence sensing relay is probably being used to trigger an alarm or flashing light whenever dead air is sensed by the device. The same alarm is probably installed at many stations NOT automated. How many times have you or one of your jocks dashed into the on-air studio after someone said, "Hey, did you know your song faded out already?" A "dead air alarm" with a silence sensor could save the day.

The P-ACR/L 100 uses up all 12 connectors on the terminal block. Power is applied to connectors 1 and 2. There are two relays in the unit, each with three connectors: the common point, a normally open point, and a normally closed point. The audio line is applied to connectors 11 and 12. The unit comes with a red LED. This connects to connectors 9 and 10 and will come on when silence is sensed. (A resistor can be changed to make the LED turn on when audio is sensed.) The holes in the housing access two controls, a sensitivity control and a delay control. The sensitivity is adjustable from 50mv to 16v. (A mic level version is available with sensitivity variable down to -70db.) The delay is adjustable from ten to one-hundred seconds. This delay is the amount of time that will pass after silence is sensed before the relays activate. Ramko makes another model, the P-ACR/L 10, with a ten second maximum delay.

Of course, depending upon how you wire things up, the P-ACR/L can be used as an audio sensor as well as a silence sensor. How many times have you missed an audio feed of one sort or another because you simply forgot it was time for it? The P-ACR/L can be connected to the audio feed line and to your recorder so that every time audio is sensed, the recorder kicks in. When the feed is over, the recorder stops. Set the delay for the shortest time, ten seconds on this model. This way, the recorder won't stop during short pauses, but waits for ten seconds of silence before activating the relays and turning the recorder off. The P-ACR/L probably has uses you'd never think of. Use your imagination. If you want to trigger something with the presence or absence of audio, the P-ACR/L might be the tool for you.

As mentioned earlier, a mic level version is available, the P-ACR/M, and both versions are available with either a ten second maximum delay or a one-hundred second maximum delay. List price on all versions of the P-ARC is $72.

These are just four of over fifty modules available from Ramko. Other handy little boxes include a variety of 3, 6, and 12 watt power amplifiers that can be used for a number of purposes. For example, do you have an old cassette deck laying around that you'd like to hook up, but don't have an amplifier for it? Stick one of these babies on the back, hook up a speaker, and you've got a complete system. There are audio controlled switchers with a "ducking" feature. Choose from a selection of 4-input mixers, distribution amplifiers, a stereo headphone amplifier and more, including modules for video applications.

Each ProMod measures 3 3/4 inches by 2 13/16 inches and is only 5/8 of an inch thick. A wiring diagram is printed on the metal housing; if the user's guide ever gets lost, all you need to know is on the box. Ramko guarantees each unit with a two-year limited warranty. The metal housings are easily opened making all components accessible. You get separate high/low level audio/digital grounds, and Ramko utilizes a floating ground concept that allows circuitry to be connected or not connected to chassis ground. The balanced electronic transformer outputs supply a full +26dBm out into 600 ohms, and the low noise floor on all the modules is certainly appropriate in this digital age.

Are there options and accessories? You bet. The 12-volt AC power supply is one. And if you want to build a rack of ProMods, Ramko offers the rack frame and all the connectors and panels you'll need to do the job right. Each rack frame holds up to five modules.

Engineers are very fond of these little boxes because many of these items are things engineers would normally have to build themselves. They're all fairly simple circuits, but many of these would require several hours of work to build. Now, for a reasonable price, the time can be better spent fixing that cart machine in your production studio instead of building some little circuit to handle some tiny task.

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