Interfire IB4700C

Price & Contact: Call for pricing; 562-903-0084, www.interfireaudio.com.
All measurements @ 14 volts unless otherwise specified.
Frequency Response (4-ohm IHF Load, 20 Hz to 20 kHz, 1kHz Ref.): +1.3 dB, -0.6 dB
L/R channel error, max deviation 20 Hz to 20 kHz: 0.3 dB
Phase Response (4-ohm IHF Load, 20 Hz to 20 kHz, 1 kHz Ref.): +42.3 degrees, -28.4 degrees
Signal-to-Noise Ratio (Below Rated Output, “A” weighted): -100 dB
Distortion at Rated Output @ 1 kHz: 0.05% @ 175 watts x 2
Output Power (resistive) minimum output 20 Hz to 20 kHz @ 1%THD+N all channels driven into 4 ohms: 68 watts x4 @ 14 volts; 56 watts x 4 @ 12.8 volts; 37 watts x 4 @ 10.5 volts
Output Power (resistive) minimum output 20 Hz to 20 kHz @ 1%THD+N all channels driven into 2 ohms: 98 watts x 4 @ 14 volts; 80 watts x 4 @ 12.8 volts; 52 watts x 4 @ 10.5 volts
Output Power (4-ohm IHF Reactive Load @ 60 Hz to 1% THD+N): 244 watts x 2
Crosstalk (Referenced to Rated Output, 20 Hz to 20 kHz): -43.3 dB
Damping Factor @ 100 Hz, 2 ohms: 36
Voltage for Rated Output: 188mV to 2.9 volts
Idle Current Draw: 0.6 amps
Current Draw @ 1/3 Maximum Power: 35 amps @ 76.7watts x 2
Efficiency @ 1/3 Maximum Power : 31%
Power-Up Noise: 42.8 dB SPL
Power-Down Noise: 19.2 dB SPL

		Interfire IB4700C www.interfireaudio.com
		Interfire’s latest four-channel amplifier offers a solid design backed by impressive power performance.		Interfire IB4700C Specs Price & Contact: Call for pricing; 562-903-0084, www.interfireaudio.com. All measurements @ 14 volts unless otherwise specified. Frequency Response (4-ohm IHF Load, 20 Hz to 20 kHz, 1kHz Ref.): +1.3 dB, -0.6 dB L/R channel error, max deviation 20 Hz to 20 kHz: 0.3 dB Phase Response (4-ohm IHF Load, 20 Hz to 20 kHz, 1 kHz Ref.): +42.3 degrees, -28.4 degrees Signal-to-Noise Ratio (Below Rated Output, “A” weighted): -100 dB Distortion at Rated Output @ 1 kHz: 0.05% @ 175 watts x 2 Output Power (resistive) minimum output 20 Hz to 20 kHz @ 1%THD+N all channels driven into 4 ohms: 68 watts x4 @ 14 volts; 56 watts x 4 @ 12.8 volts; 37 watts x 4 @ 10.5 volts Output Power (resistive) minimum output 20 Hz to 20 kHz @ 1%THD+N all channels driven into 2 ohms: 98 watts x 4 @ 14 volts; 80 watts x 4 @ 12.8 volts; 52 watts x 4 @ 10.5 volts Output Power (4-ohm IHF Reactive Load @ 60 Hz to 1% THD+N): 244 watts x 2 Crosstalk (Referenced to Rated Output, 20 Hz to 20 kHz): -43.3 dB Damping Factor @ 100 Hz, 2 ohms: 36 Voltage for Rated Output: 188mV to 2.9 volts Idle Current Draw: 0.6 amps Current Draw @ 1/3 Maximum Power: 35 amps @ 76.7watts x 2 Efficiency @ 1/3 Maximum Power : 31% Power-Up Noise: 42.8 dB SPL Power-Down Noise: 19.2 dB SPL
		by Brian Smith

		The IB4700C is a four-channel amplifier with power ratings of 90 watts x 4 or 175 watts x 2 into 4 ohms. Features include gold-plated connections, selectable bass boost, and internal crossovers with selectable cutoff frequencies. Performance The IB4700C performed quite well during its test session, although some of the power ratings published for the unit seemed a little off. Rather than 90 watts x 4 we saw closer to 75 watts x 4 through most of the amp’s range when driving all channels into 4 ohms. At the other end of the spectrum, the amp appears to be substantially under-rated in a bridged configuration and had no problem producing 244 watts x 2 into our 4-ohm reactive loads. No 2-ohm ratings were supplied, but the amp appears to be capable of about 100 watts x 4 with all channels driven into two ohms. Who wouldn’t trade good performance at 4 ohms for better performance at 2 ohms these days? Sort of like trading a Chevy for a Cadillac. Most impressive was the amp’s performance during both of our power response tests. At both 2 and 4 ohms, and with supply voltages from 10.5 to 14 volts, the IB4700C ran through the test without a hitch. That’s a sure sign of a relatively stable and well-behaved amplifier and one that we see less and less of as time goes by. As with the other amps that we’ve seen from Interfire, this unit has a slight lump it its response that’s centered around 30 Hz. It’s not much, but it would likely be enough to make the amp sound “warmer” in a demo/display comparison. The amp also exhibits a sizable bump in response around 70 Hz with the high pass crossover at its lowest setting. The slight rise at 30 Hz is unlikely to be objectionable, but the 3 dB lump at the low end of the high pass filter might. However, either characteristic should be relatively easy to tune out with a decent EQ. On the noise front, the IB4700C managed a respectable S/N of -100 dB and turn on/off noises of 42.8 dB SPL and 19.2 dB SPL, respectively. Connections & Adjustments Connections to the IB4700C include RCA inputs and 5/16-inch spade receptacles for all power and speaker connections. All adjustments on the amp control a pair of channels and include input sensitivity, stereo/mono mode, bass boost select (0 dB, +6 dB, +13 dB @ 37 Hz), crossover mode select (high pass, low pass, full range), and crossover frequency selectors (50 Hz, 80 Hz, 150 Hz). Installation From an installation standpoint, the IB4700C should be quite easy to work with. The amp’s input sensitivity is the only variable control, which somewhat limits overall flexibility, but it also limits complication. The remainder of the amp’s controls are activated by relatively large switches, which have positive action, a sensible layout, and are clearly labeled. The amp’s heat sink is one of the smooth, high mass designs. Not one of my favorites, but it should work at least as well as similar designs. The sink has a couple of sizable fins running up each side, but they’re capped, essentially forming enclosed channels up each side of the amp. For the best possible heat dissipation, I’d suggest mounting on a vertical surface with the amp arranged so that the channels in the heat sink are vertical as well. And, as always, if you’re gonna’ drive it hard, a small fan wouldn’t hurt.