1980's Crate CR-285B Bass Amplifier information thread

[scuzzy]

Just making this thread as a resource for (the few) people who search and are interested. I found little information online regarding this amplifier but feel its solid enough and unique enough to post in case others want a resource. If anyone reads and has anything to contribute, please do. I use forums constantly for my used gear purchases.

It is a mid to late 1980's model Crate solid state bass amplifier. Internal and External speaker outputs that say 2ohm stable. 150 watts at 4 ohms. Made in the USA at the SLM factory in St. Louis Missouri.

I did some EQ plotting on my cell phone. Started flat with my DP custom scroll. Just plucked the A string and paused the graph. I did one with the amp flat and one for each control manipulation. The findings are as follows.

FLAT

LOW MAXED

MID MAXED

HIGH MAXED

BRIGHT SWITCH ON

WARMTH MAXED

PRESENCE MAXED

 

[scuzzy]

So, after playing on this amp through my B15 cab, it just sounds amazing. I want to take it up to the church I play at instead of my other rig, but we run DI out of an RBI head, and this old crate only has a line out. We don't have a sufficient mic for a bass cab. Any thoughts? How different is a line out from a modern DI?

 

[glocke1]

what app is that?

 

[mexicanyella]

Cool old head; I used to have a CR-160 1 x 12 guitar combo from the same era, with similar cosmetics. As I recall it had a pretty low-to-medium gain dirty channel with a nice warm sound. Of course that was in the early 90s and I wanted something that sounded like a Soldano then. Wish I still had it.

Looks like it's got some nice features for bass.

 

[Crater]

How different is a line out from a modern DI?

Line outs are "unbalanced" signals, just a "hot" and "ground". A balanced output, by contrast has a "+" , a "-" and a ground. Having the + and - line helps cancel hum, similar to a humbucking pickup. Just connect the line out to an standard (passive or active) DI box using an instrument cable. The DI converts the unbalanced signal to a balanced signal which is best for feeding a PA system, and also provide electrical isolation to prevent ground loops.

 

[beans-on-toast]

Here is the manual:

 

[scuzzy]

Here is the manual:

nice! i think i searched, and i think i couldn't find it. so a heart-felt thank you.

and now i gotta find the matching 2x15" cab. thanks.

 

[beans-on-toast]

nice! i think i searched, and i think i couldn't find it. so a heart-felt thank you.

and now i gotta find the matching 2x15" cab. thanks.

The schematic is on the ampeg site. Never hurts to grab a copy in case a repair is required. It isn’t something that I can post but you can get it. Just enter the model number in the search window.

Link Removed

 

[scuzzy]

i know crate can be a bad word in the instrument world, but this amp truly has a great sound. even my brother in law, who is a good guitarist and a very good audio engineer said it sounded great on guitar, for a nice clean tone. handles pedals great as well. the ampeg b15 cab probably has a bit to do with it all as well. it's a nice package.

 

[Ralphieboy57]

Thank you SCUZZY of the info on this Bass Head. I picked one up for $35.00 at a swap meet. tHIS HEAD KICKS BUTT. Nice warm tone. Cool onboard EQ. Respectable volume.

 

[scuzzy]

Thank you SCUZZY of the info on this Bass Head. I picked one up for $35.00 at a swap meet. tHIS HEAD KICKS BUTT. Nice warm tone. Cool onboard EQ. Respectable volume.

That is an absolute steal. I still love it. Great on bass and guitar. Sounds great with both my cabs.

 

[Nicholasville]

Hey I really need some help. Recently I found a capacitor dislodged in the chassis of my CR and I'm hoping someone can take a few pictures of the inside of their head. Specifically I think it broke off from the eq pcb but I'm not sure. Posted are pics of what I'm dealing with. Thank you !

 

[beans-on-toast]

That’s a wire wound cement resistor, not a capacitor.

 

[Nicholasville]

I think it came from behind the 3 band eq. If I can get a picture of a normal pcb I'll know.

 

[Nicholasville]

I think it was right here but I don't want to guess

 

[scuzzy]

I am at work till the morning, so no help yet. It may be a day or two but I'll try to dig in it and see what pics I can get for you.

 

[scuzzy]

On another note, I bought a crate BT-350 rack mount power amp and that thing is another winner. Leaving it at the church so weight doesn't matter. I have nothing but respect for these SLM crate heads.

 

[Nicholasville]

That’s a wire wound cement resistor, not a capacitor. It’s origin is anyone’s guess.

Yeah I thought maybe it was a resistor cause it's like holding a construction brick. Very chalky. Never seen one like this before.

 

[beans-on-toast]

Yeah I thought maybe it was a resistor cause it's like holding a construction brick. Very chalky. Never seen one like this before.

There are two of those resistors in the amp. R44 and R45. They are 0.22 ohms +/- 5% tolerance, 10 watts. They are connected in parallel, one end to ground, the other to the speaker output jack sleeves and R42.

The resistors are in the power amp, not the preamp as you suspect. Look for a second resistor just like the one that fell out. Then again, if one came out perhaps both did. You may have to trace the circuit using the schematic to find them. Probably on the board that we are seeing the back of in your images

Download the schematic here:
Link Removed

 

[Nicholasville]

Nice!!! That's very helpful