Recent Posts

Pages: [1] 2 3 4 ... 10
Q & A / Re: Sunn Orion Preamp Schematic?
« Last post by oldtimer on Yesterday at 06:16:45 pm »
have an orion pre amp.....bought the amp in 71    used it about 4 years, started playing smaller gigs...put the covers on it in 75......40 years later took it out of garage and plugged it in ..died in 5 mins, on low volume ...some basic tests poit to the preamp...anyone out there no where to get a schematic.....tia!
Site Improvement / The site will be moving soon
« Last post by tboy on Yesterday at 12:55:03 am »
The sunn Forum will be moving soon, to a new server that will be secured with https, and also to a new domain, so it will no longer be a sub-domain of
Q & A / SPL 8028 Crossover
« Last post by dgillon on August 08, 2018, 07:20:58 am »

Does anybody know where I can get a schematic/wiring diagram for the crossover in these cabinets?  I removed the circuit from mine during some repairs, and over the course of moving to a new state lost the original components, and the schematic I had drawn up.

Q & A / Re: Brown Box ?
« Last post by Ryan Phelps on August 07, 2018, 07:32:53 am »
Variacs have been used for ages......either to adjust the AC voltage to the amp's original specs, or just to "brown" the sound......more distortion. Eddie Van Halen was noted for doing this back in the day.

The Brown Box manufacturer is referring to AC wattage consumption (amps x volts = watts) of the amp. In the case of this device, it is limited to 5 amps of current.....which will handle most amplifiers.

A more rudimentary version of the Brown Box is a bucking transformer.....basically reduces the AC wall voltage down to something closer to the old voltage in years past. These have been used for years by tube hi-fi guys. A major benefit of using one of these devices is to lower the secondary voltages coming from the power transformer so that the voltage rating of the filter capacitors are not exceeded.....and the filtered DC voltages fed to the plates of the tubes, are closer to the original design. Lots of schematics for these on the interweb, but not for amateurs!

For tube rectified amps, one can substitute for a less efficient rectifier that has more voltage drop....thus reducing the secondary voltage fed to the power supply and tubes. But need to be sure the rectifier tube does not exceed the current capacity of the amp's power transformer.
Q & A / Re: Brown Box ?
« Last post by ducatidoc on August 06, 2018, 01:06:48 pm »
Here's a link to the one I got:

If you scroll down to the description it says "Be sure to Check the Manufactures info plate on the rear of the Chassis for input watt requirements or simply call us, we love to help", which sounds mighty friendly of them. My '69 with tube rectifiers says 117V, so that's what I adjusted the box to. 
Q & A / Re: Brown Box ?
« Last post by Isaac on August 06, 2018, 08:44:47 am »
I've never heard of a Brown Box. For years, I've read of people using autotransformers such as Variacs to adjust the input voltage, but that's usually to use it as a kind of master volume.
Q & A / Brown Box ?
« Last post by ducatidoc on August 06, 2018, 06:17:10 am »
Anyone else have one to control their input voltage ? I've been told that the older Sunns were built to work optimally at 110V AC, although my '69 2000S says 117V on the rear.  The outlet Ive been using reads about 121V so the box brings it down to 117V.
Q & A / Re: Bass through Guitar amp?
« Last post by Isaac on August 03, 2018, 08:55:29 am »
And there's a good chance that a guitarist would like the sound better through guitar speakers. But in terms of safety and damage, guitar through bass speakers is not a problem.
Q & A / Re: Bass through Guitar amp?
« Last post by EdBass on August 02, 2018, 10:36:51 am »
You won't hurt the amp or the speakers (assuming the drivers are in good shape and not worn out or damaged), however you could maybe get a little more volume using guitar drivers.
Q & A / Re: Bass through Guitar amp?
« Last post by Ramm on August 01, 2018, 07:42:55 pm »
And if it's the other way around?
guitar in bass amplifier?
Should the speakers be replaced by guitar ones?
Pages: [1] 2 3 4 ... 10