Dean Markley Spectra Series H-160B Bass Head

There is very little info on these a these amps so I did some searching and reading, some disassembly and inspection, and here is my review.
The Dean Markley Spectra Series H-160B Bass Head was made in the USA from 1982-86 by Dean Markley Electronics of Santa Clara CA. It's a 160 watt solid state amp with power coming from four Motorola T-03 cased Darlington power transistors mounted on a heat sink along with a thermal protector circuit. Construction is typical 1980s discrete components on two very well made PCBs. One for the preamp and one for the power amp. The power amp board has only about 100 components. The preamp board has three op amps as part of the EQ section along with a few resistors and diodes.

Up front it has two channel inputs. Input A is unbalanced 1/4" and input B is balanced 1/4". There's a built in compressor which is activated by a front mounted push on/push off switch and next to that is the power switch. Six knobs control volume (gain), treble, middle, midshift, bass, and master volume. The midshift knob changes the center frequency of the midrange.

On the back is a 6 amp fuse holder, two 8 ohm speaker outputs wired in parallel, preamp out and power amp in. It has a very large power transformer so it has the headroom to deliver a big sound.

I've used this amp with every kind of bass from standup to stick bass and it handles everything just fine. Passive pickups need a bit more gain but still produce enough volume for playing live in a small venue. As long as the load is around 8 ohms, just about any speaker cabinet with 10" speaker or larger works fine. With a single 15" driver it delivers a fat dry tone. It has some warmth, but nothing like a tube head. Played through a 4 x 10 cabinet it has punch but not as much headroom... more growl. When it distorts, it does so smoothly and recovers quickly. It's tonal range is quite broad and some time spent tweaking the knobs can result in some very pleasing tones.
I've also used this head for guitar and PA purposes. It performs better than you would expect. Therte's plenty of treble overhead for vocals, and the midshift helps eliminate harsh mid tones. The bass has a good deal of saturation potential for vocals when coupled with the built in compressor, which is basically preset like a soft limiter.

This amp is rock solid. I bought mine at a pawn shop for a mere $60. It spent it's former life as a rental from a music store. I've used it for all kinds of things over the years and it's still goin strong. It has survived being a rental unit, storage in damp environments, dust and cockroaches and just about everything I have thrown at it. It's a good work horse!

You're on your own here... :)

In my 30 years of being around amps and music and sound engineering, I can honestly say that this amp has delivered over and over and stayed with me these past ten years because it's just a tough old bastard! If you ever see one for sale, buy it. I wouldn't pay any more than about $150 for one.