Altec Bolero 890c schematic

[vincenzo]

Hello everyone, my first post here. I just picked up a pair of Bolero 890c speakers (well about a year ago actually). I had thought they might be nice used in a 2nd system with a Marantz receiver. But when I hooked them up to my tube rig I was pleasantly surprised at what came out. A nice change from the studio monitors I was using there. Needless to say, they've stayed in that system since. I am now thinking of having the capacitors in the crossovers replaced as well as bypassing the 3-way switch in the back. Does anyone know where I might find a schematic?

One more question, should I rotate the woofers?

Thanks all.

[Phil-G]

wow no ones replied? I myself don't have a schematic.

Gathering info on the Altec Bolero 890C

http://www.hostboard.com/forums/f700...lero+crossover

Mtaching Rear Speakers :)

[Elitopus1]

I would definitely recap them.

Maybe put an alligator clip jumper across the switch and see if you like how it sounds? The switch itself might add some resistance, even in the WFO position. You might like how it sounds, or need to put a small resistor in place of the switch.

Good luck, and let us know how it turns out

[Earl K]

Hi,

I don't have a schematic ( & I've never seen one posted on the .net ) but typically the values are quite clearly printed on the body of the capacitors ( both the Callins & AC brands when present ) .

[miker1]

Each 890C crossover uses two 6uF and one 3uF caps. The switch controls three parallel resistors across the tweeter inputs. Not sure there's much sonic advantage to bypassing the switch. Also never seen a crossover schematic but you can find photos of the crossover from people that have recapped them.

[mah]

Altec Bolero 890C Two Way Crossovers | #56499457 Some pics if someone can do a schematic:

[Old Guy]

Each 890C crossover uses two 6uF and one 3uF caps. The switch controls three parallel resistors across the tweeter inputs. Not sure there's much sonic advantage to bypassing the switch. Also never seen a crossover schematic but you can find photos of the crossover from people that have recapped them.

Looking at the photo, the resistors connected to the switch aren't parallel. Each one connects to a different terminal. So each terminal appears to select a different series resistor for the tweeter.

[Elitopus1]

Seems like even the +3db setting has a resistor before the tweeter. So you could jumper from the switch input directly to the resistor of your choice. If you just solder a piece of wire in the mod would be reversible.

[miker1]

The three resistors controlled by the switch are 15, 15 and 30 ohm. It's a little confusing to me how the slide switch is wired. When I measured the resistance with the drivers removed (resistance across the leads going to the tweeter) I got 31.8 ohms at the +3 dB setting; 10.6 at the Norm setting; and 7.6 at the -3dB setting. Given some tolerance, it seems the -3dB setting parallels the two 15 ohm resistors, and the Norm setting parallels the 30 and one of the 15 ohm resistors.

- - - Updated - - -

Here's my crude schematic of the crossover with the switch details uncertain to me.

[Old Guy]

I suspect you have it right. Looks like Altec did an EQ with the series resistor and cap across it.

As said, I doubt any sonic improvement from bypassing the switch.