BGRA: Amplified Music Products (AMP) BH-420

Manufacturer Amplified Music Products (AMP) Model BH-420
Reviewer Brian Rost
Experience Item owned
Review Date Price paid $900 list in 1987, $600 (new), $150 (used)
Dimensionstwo rack spaces
Wattage400 watts @ 4 ohms, 220 watts @ 8 ohms
Speaker(s)none (head)
Effectspre-EQ loop, post-EQ loop
Controlsvariable limiter, crossover, "enhance"
OtherXLR direct out, headphone jack
Amplified Music Products, or AMP, is no longer in business. This amp, which was made in the late 80s, was a precursor to both the SWR and Eden heads of today; SWR founder Steve Rabe did the original AMP preamp designs and Russ Allee, who also designed the Acoustic 360 amp, was a consultant on the design of the Eden WT heads. As a result, this head shares a lot of features with those amps, but sells used at a much lower price, due to low brand recognition. I own two, bought my first one brand new in 1987 for $600 and the second used in 1997 for $150; let's face it, $150 for any working 400 watt bass head is a steal. Typical used prices seem to be in the $2-300 range for these heads. The amp has two inputs, one padded by 10 db. You can only use one at a time, so if you play two basses you can't keep both plugged in. The gain control has a clip LED to aid in setting the optimal level; next is the limiter which has a threshold LED to let you know when it is active. Below this knob is the "enhance" switch which cuts low mids while boosting lows and highs. this is similar to the SWR "aural enhancer" except it has only one setting rather than a variable control. A footswitch jack is provided so you can kick the enhance circuit in and out while playing. The EQ is six bands, the four mid bands have sweepable frequencies. Some players may feel the mid bands end too low (highest frequency is about 1000 Hz) for modern EQ tastes. After the EQ is the unique "tone balance" control. Imagine having a bass and treble control on one shaft; turning counterclockwise boosts bass while cutting treble, clockwise boosts treble while cutting bass. It's evry cool for making quick EQ adjustments when your sound is too thin or too muddy. The last two controls are the master volume and crossover. Despite having a crossover, this is a mono amp, you need a second power amplifier to do biamping. The back panel has an XLR direct out (unaffected by any front panel controls), pre-EQ effects loop, line out and power amp in (can be used as post-EQ effects loop), crossover outputs, two speaker outputs and a headphone jack (LOUD!!!!!) which does NOT disconnect the speakers. The power cord is removable and you can set the amp up for international voltages if world touring is in your future. The power switch is in the back (bad when rack mounted). There are no heat sink fins! The entire case acts as a heat sink, so it gets hotter than you might expect. A handle is mounted on the side for carrying, or it can be racked with the optional rack ears (if buying one used, you may find the handle or rack ears not included, then you're on your own). Some heads were shipped with wooden trim strips on the side as well, these are strictly cosmetic. The basic tone of the amp is very open yet warm. It is a solid state design, no tubes even in the preamp (unlike current SWR and Eden amps). It has plenty of power for most applications. The amp is lightweight (about 20 punds) and small so if not racked, it's easy to lug around. I have had exactly one problem with my first one, one of the input jacks needed to be replaced after about eight years of steady use. If one of these amps is available used at a good price and you are looking for a "por man's SWR" I'd highly recommend it. Other AMP heads you may find are the BH-220 and BH-260 models which are lower power and lack a few of the features (no limiter, crossover or sweep EQ). There is also a separate preamp (SL-1) and rarest of all is a version of the amp sold under the Gibson brand name, the Gibson GB-440.
construction (100%)
clarity (100%)
value (100%)
overall (100%)
The BGRA is generously underwritten by David King of Bass Guitar Systems.
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