Recent Posts

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91
Q & A / Re: 1968 Sunn Sceptre reverb troubleshoot
« Last post by GrannyGremlin on November 04, 2017, 10:43:31 am »
Both of my vintage Sunns came to me with the reverb not working (1200s and a Solarus 6550 version).  In both cases the fix was to clean the reverb jacks and plugs at both ends; probably never been cleaned and they're old and grimey.  Surprised me that it was something so simple, but like I said, same fix on both amps.
92
Q & A / 70s (vibrato/Reverb) footswitch wiring
« Last post by GrannyGremlin on November 03, 2017, 09:46:56 am »
So I found an old Sunn footswitch, period correct for my 1200s and Solarus amps, but someone has previously used it as a chassis donor for some other type of device (there was a large cap and a relay in there when I got it; lots of leads not connected to anything at 1 end).  I want to wire it up and put it to use.

My question: Are the ground (sleeve) wires for both RCA jacks common (or can they be without causing issues)?  Specifically, I was hoping to be able to use balanced mic/line cable (2 conductor coax w shield) from switch to amp vs dual monoconductor coax cable (i.e. hifi interconnect  or 2 x guitar cable) which would be bulkier.  Any reason I shouldn't do this?

Since this is pretty much chassis only, I was going to put a TRS jack at the switch end and have a detachable 1/4" TRS to dual RCA cable as the interconnect.  Also considering adding indicator LEDs for both FX (since all the stomp switches I have are at least 2 pole anyway), but maybe that's not worthwhile.  If i do it would be battery only (it would last forever just powering 2 LEDs and be cleaner than running a power cable to it).
93
Q & A / Concert Controller 2 - Loud Pop When Shutting Off
« Last post by Jeff Troy on October 27, 2017, 04:12:46 pm »
Hi, Guys,
I'm pretty decent with cosmetics, but I don't do electronics and my repair guy is gone.
I use a Concert Controller 2 (6-CH) for rehearsal with a swing bad - only two vocals and we don't mic anything else - but when I turn off the unit, it makes a horrendously loud pop.

I'm only running a pair of sunn floor monitor speakers in the rehearsal room, but the last time I switched off, it did some damage. I didn't know that anything was wrong until the next time I turned it on, and then it was pretty clear that the the mixer has a problem. The horns in the monitors seem to respond, but the speakers do not. Pretty sure the pop in the controller blew them out.

I plugged in a 412SR cab and a Concert Horn Accessory. They all work fine. I went back to the monitors and still no speaker response. All the hookup cables are good, and it's unlikely that the speaker wiring inside both monitors would go south at the same time.

Anybody know what this is, and how to fix it? Someone mentioned something about a capacitor on the on/off switch, but he never followed up. Please help if you can.

Please respond to  jefftroy@aol.com  I don't get on this site so often anymore.

Thanks and regards...
94
Q & A / Re: Sunn 215B buzz/rattle.
« Last post by Isaac on October 25, 2017, 07:10:17 am »
Before giving up, I'd rotate the driver. It could be cone sag. When reinstalling, make sure the hardware is snug, but not overtight. Overtightening can warp the frame, causing this exact symptom.
95
Q & A / Re: Concert Bass Mid control not working
« Last post by _peter on October 25, 2017, 04:03:26 am »
Hi,

according to this schematic: https://schematicheaven.net/newamps/sunn_concertbass.pdf
the bass pot isn't stacked on the mids pot as in the usual fender/marshall tonestacks.
With bass at zero, the signal at the mids pot is shorted to ground. Therefor the mids pot can't work in this situation.

Cheers,
Peter
96
Q & A / Re: Sunn 215B buzz/rattle.
« Last post by _peter on October 25, 2017, 02:14:58 am »
Hi,

there either seems to be an object between the coil and the magnet or the coil isn't centered anymore.
In both cases there's nothing you can do about it but recone or swap the speaker.

Cheers,
Peter

97
Q & A / Concert Bass Mid control not working
« Last post by Hd0521 on October 24, 2017, 09:40:32 pm »
With the mids dimed and the bass and treble at zero there is a very low volume tone coming through. If I back the mids down to zero the volume of that tone doesnít change. If I dime either bass or treble the volume increases. Iím assuming itís a passive Eq stack. I opened the amp up and it looks like the original pots wired right to the board. Any solution before having the pot replaced?
98
Q & A / Sunn 215B buzz/rattle.
« Last post by Hd0521 on October 24, 2017, 09:30:31 pm »
Brought home a concert bass Head and 215B cab today. Thereís a buzz (similar to a fuzz effect) from the top speaker only when I play. If I lightly place my hand on the lower part of the speaker cone it goes away. If I light place my hand on the upper part of the cone itís more dramatic. Any ideas? Thanks in advance.
99
Q & A / Re: Footswitch
« Last post by Watson on October 24, 2017, 08:37:36 am »
Here are a few shots of the beta foot switch circuit board in a unit I have.

100
Q & A / Re: Footswitch
« Last post by loudthud on October 23, 2017, 08:44:59 pm »
Sorry, I don't have anything to contribute on the Beta footswitches. These are pretty rare and at least one company was making a clone for use by people needing one for their Beta amps. I know in the early years Sunn used an aluminum extrusion with a U shaped sheet metal bottom-side plate. In later years they might have run out of the extrusion and not reordered because there is usually a 500 or 1000 pound minimum order.

It would be nice if you could snap a clear picture of the inside of the footswitch and post it here. TIA!
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