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Acoustic Amplifiers

Early Acoustic amplifiers
 
Early Acoustic amplifiers

I’m not really an amp guy, but I have two early Acoustic catalogs, from early ’73 and ’74. We might as well document the amps therein, since you’re going to find them and few are out there talking about these solidstate babies while the tube-hegemony reigns.

Among the innovations Acoustic claimed for itself was first use of front-loaded speakers and snap-off grills, making speaker changing easier. Other technical features included dual sensitivity inputs for each channel, the left being more sensitive (e.g., for the lead guitar), the right slightly less (e.g., for the rhythm guitar or for very high-output pickups). 130 and 150 Series amps featured something called “interlocking protection circuits” that let you daisy chain the channels with a guitar cable to get an overdrive effect at moderate volume levels.

Acoustic also touted its tremolo circuit as being the only “true” one available, with a potential for 90 percent volume cut. Remember, tremolo is variation in volume, vibrato is variation in pitch frequency (guitars have vibratos, not tremolos). Acoustic’s 450 and 470 Series amps had symmetrical distortion circuits that eliminated hum and non-harmonic content, and both had a switch allowing you to play either lead or bass guitar through them. These also featured channel switching so you could have two different tonal settings. Some Acoustic amps also had a booster output, allowing you to power slave amplifiers after the power output circuit. Some Acoustics also featured graphic equalizers.

Early Acoustic amps featured charcoal grey tolex on the cabinets with black grilles usually surrounded by white piping. Control panels would either be aluminum or more likely black, usually with the logo and model number in a strip running along the bottom of the panel.

Here are the amps listed in the early ’73 and ’74 catalogs. Availability dates are from another source and should be taken with a large grain of salt, since I can’t confirm their accuracy. Don’t ask me why the 146 is included in the 150 Series!

130 Series
1971-’76 Model 134 Guitar Amp (combo, 125 watts RMS, 2 ch, hi/lo inputs, bright sw, vol/treb/bs, rev, trem, 4×10″ open back, wheels, cover). 1971-’76 Model 135 Guitar Amp (combo, 125 watts RMS, 2 ch, hi/lo inputs, bright sw, vol/treb/bs, rev, trem, 2×12″ open back, wheels, cover). 1972-’77 Model 136 Bass Amp (combo, 125 watts RMS, 2 ch, hi/lo inputs, bright sw, vol/treb/bs, 1×15″ horn loaded/ducted port, wheels, cover).

150 Series
1970-’76 Model 154 Guitar Amp (piggyback, 125 watts RMS, 2 ch, hi/lo inputs, bright sw, vol/treb/bs, rev, trem, 6×10″ sealed, wheels, cover). 1970-’76 Model 155 Guitar Amp (piggyback, 125 watts RMS, 2 ch, hi/lo inputs, bright sw, vol/treb/bs, rev, trem, 4×12″ sealed, wheels, cover). 1972-’76 Model 146 Bass Amp (piggyback, 125 watts RMS, 2 ch, hi/lo inputs, bright sw, vol/treb/bs, 2×15″ tuned bass reflex, wheels, cover).

270 Series
1971-’76 Model 271 Guitar Amp (piggyback, 275 watts RMS, hi/lo inputs, bright sw, vol/mid/treb/bs, dist, rev, trem, 5-band EQ, footsw, 2×15″ Altec 418 sealed, horn, wheels).
1974-’76 Model 274 Guitar Amp (piggyback, 275 watts RMS, hi/lo inputs, bright sw, vol/mid/treb/bs, dist, rev, trem, 5-band EQ, footsw, 2-4×12″ sealed, wheels).

450 Series
1974-’76 Model 454 Guitar Amp (piggyback, 170 watts RMS, hi/lo inputs, bright sw, vol/mid/treb/bs, accessory vol, symm dist, 5-band EQ, lead/bass sw, direct out, accessory in/out jack, footsw, 6×12″ sealed, wheels). 1974-’76 Model 455 Guitar Amp (piggyback, 170 watts RMS, hi/lo inputs, bright sw, vol/mid/treb/bs, accessory vol, symm dist, 5-band EQ, lead/bass sw, direct out, accessory in/out jack, footsw, 4×12″ sealed, 2 horns, wheels).
1974-’76 Model 456 Bass Amp (piggyback, 170 watts RMS, hi/lo inputs, bright sw, vol/mid/treb/bs, accessory vol, symm dist, 5-band EQ, lead/bass sw, direct out, accessory in/out jack, footsw, 2×15″ tuned port, wheels).
1972-’76 Model 300 Power Amp (slave head, 275 watts RMS, 2 or 4 ohms, 0.4 percent THD, booster output, vol, 2 speaker outputs).
1972-’77 Model 371 Bass Amp (piggyback, 275 watts RMS, hi/lo inputs, bright sw, vol/mid/treb/bs, 5-band EQ, 1×18″ Vega in folded horn encl, wheels). 1974-? Model 400 Power Amp (stereo PA reinforcement, 375 watts RMS @ 2 ohms, 200 watts RMS @ 4 ohms, 0.25 percent THD, power sw).

470 Series
1974-’77 Model 474 Guitar Amp (piggyback, 170 watts RMS, hi/lo inputs, bright sw, vol/mid/treb/bs, accessory vol, symm dist, rev, trem, 5-band EQ, lead/bass sw, direct out, accessory in/out jack, footsw, 6×12″ sealed, wheels).
1974-’76 Model 475 Guitar Amp (piggyback, 170 watts RMS, hi/lo inputs, bright sw, vol/mid/treb/bs, accessory vol, symm dist, rev, trem, 5-band EQ, lead/bass sw, direct out, accessory in/out jack, footsw, 4×12″ sealed, 2 horns, wheels)
1974-’76 Model 476 Bass Amp (piggyback, 170 watts RMS, hi/lo inputs, bright sw, vol/mid/treb/bs, accessory vol, symm dist, 5-band EQ, lead/bass sw, direct out, accessory in/out jack, footsw, 2×25″ tuned port, wheels).
1972-’76 Model 806 Monitor System (75 watts RMS, 8 ohms, 1×12″). 1974-? Model 808 P.A. Speaker System (175/350 watts RMS, 4 ohms, 2×15″, 3xHepner-Vega horns, 2-way horn loaded cab).

850 Series
1972-’76 Model 850 Series P.A. (head, 8 ch., 275 watts RMS, ch in/out sw, input to master jack, accessory in/out jack, booster output, 0.4 percent THD, rev, VU meter, master vol, rev, bright sw).
1972-’76 Model 801 Speaker Column (x2) (six 6″x9″ horns).
1972-’73 Model 803 Speaker Column (x2) (100 watts, 4 ohms, six 6″x9″ horns)
1974-? Model 804 Speaker Column (x2) (2×15″, 3×10″, horn).

870 Series
1974-? Model 870 Series PA (head, six ch. expandable, 170 watts RMS, ch in/out sw, accessory in/out jack, recording in/out jack, booster output, 0.4 percent THD, rev, hi/lo Z, 5-band EQ).
1974-? Model 801 Speaker Column (x2) (6×10″).
1974-? Model 804 Speaker Column (x2) (2×15″, 3×10″, horn).

MF VIII Public Address System
1972-’73 Model 880 Mixer (8 ch).
1972-’76 11x Model 300 Power Amps.
1972-’76 16x Model 801 Speaker Columns.
1972-’73 4x Model 802 Sectorial Horns (two horns).
1972-’76 4x Model 806 Monitor Speaker Systems.

MF IV Public Address System
1972-’73 Model 880 Mixer (8 ch).
1972-’76 6x Model 300 Power Amps.
1972-’76 8x Model 801 Speaker Columns.
1972-’73 2x Model 802 Sectorial Horns (2 horns).
1972-’76 4x Model 806 Monitor Speaker Systems.

MF VI Public Address System
1972-’73 Model 880 Mixer (8 ch).
1972-’76 8x Model 300 Power Amps.
1972-’76 12x Model 801 Speaker Columns.
1972-’73 2x Model 802 Sectorial Horns (2 horns).
1972-’76 4x Model 806 Monitor Speaker Systems.
1974-? Model 890 Mixing Console (16 ch).
1972-’73 Model 910 Studio Amplifier (combo, hi/lo inputs, vol/treb/mid/bs, bright sw, rev, trem, dist, sustain, five-band EQ, separate vol w/footsw, 1×12″).
Acoustic made a ton of other amps following these early models, including some tube models in later years. We’ll leave that discussion for later.



This article originally appeared in VG‘s July and ’98 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.

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