SWR Stereo 800 help please

alec · #1 05-22-2011, 01:03 AM

I'm looking at a rig that includes an SWR Stereo 800 but it has an issue.

When I plug into the left channel input, the right speaker outs are fine, but the left speaker outs are distorted and quieter than the right.

The right channel input doesn't work at all with left or right outs.

I think this situation is the same whether the amp is in bridge mode or not, but it was a bit hard to tell because the button was broken off.

Does this sound like costly thing to fix?

alec · #2 05-22-2011, 04:48 AM

I've found that the right channel isn't supposed to work in bridge mode, so that point is solved.

It's just the distorted right speaker outs that's the issue now. If the fuse was blown, there'd be no signal rather than a distorted one, right?

alec · #3 05-22-2011, 04:52 AM

I should add that I was using a single cab to test it out.

BassmanPaul · #4 05-22-2011, 08:48 AM

Sorry Alec but it's tech time. Take it in and get an estimate.

alec · #5 07-04-2011, 11:33 AM

I ended up buying it and a 800 watt Labsystems 4x10 for AUD$400 yesterday.

The cab seems to be in great working order (now that I've cleaned the cobwebs out of it) but it's hard to be sure because things rattle in my house when I crank it so I'm not sure if the speakers are buzzing.

The Stereo 800 has all sorts of issues though. The bent rack ears tell me its been dropped at least once, and almost all the writing has been worn off it along with a lot of paint. Used and abused.
One input jack is a bit loose and crackles when jiggled. The volume controls are scratchy. The left speaker outs are distorted. It should have 10A fuses but the left channel is using a 4A (could this be causing distortion? I'll swap the fuses in the morning to test).
And when I use the preamp of my 300 watt Trace Elliot via the effects send (cranked up to 10), the SWR at 10 is no louder than my Trace with the master volume at just 2.5!
I hear no difference in volume between stereo and bridged mode (in the only setup that works for both modes). I think its 700w vs 800w and don't know if there's supposed to be much difference.

I was expecting some serious volume. Is my Trace just a much louder amp despite its rating?

Does it even sound like its worth paying someone to look at it?

Jeff Scott · #6 07-04-2011, 04:21 PM

Probably blown output transistors. As Paul said, tech time.

**B-string** · #7 07-04-2011, 04:41 PM

Don't expect a big difference between 700 and 800 watts. You need a lot more than 100 watts to detect any real difference above 700 watts.

alec · #8 07-04-2011, 08:38 PM

I dropped it off with a tech this morning. It turns out I wasn't using bridged mode anyway because I wasn't using the banana jacks. It sounds like the most I was getting out of it was 350w which goes some way to explaining the lack of volume.
We'll see what the man says.

**Ronny49** · #9 07-06-2011, 09:20 PM

You don't need to run from the banana's to bridge. I used to own this amp and I got a lot of power out of it running bridged and daisy chaining from the left MONO out to the 410 cab and then from the 410 to the 115 I have. Worked great... loud and punchy!

murphy · #10 07-06-2011, 09:47 PM

I love my stereo 800

One loud and warm sounding amp

T-Bird · #11 07-07-2011, 12:53 AM

Hi.

Good to hear that You decided to take the amp in.

I haven't worked on SWR 800's, but if it's a discrete design like its smaller (/older) brothers, a -typical to that design- drifted bias and blown transistor(s) would be my guess as well.

It's very easy to determine whether the transistors are blown, even without opening the lid, so do make sure that the tech does an estimate diagnose first. Otherwise the seemingly great deal may turn sour.

Regards
Sam

alec · #12 07-07-2011, 01:28 AM

Ronny, the tech was adamant that bridge mode only applies to the top bananas, and the manual and drawing on the back of the head seem to agree. It still works from a 1/4" out, but apparently only one channel is providing the juice.

Since I was using an 8 ohm cab, I was only getting 220w which makes the low volume seem more reasonable.

It will be sweet if this unit can be fully repaired for a reasonable cost (I am getting an estimate first). If not, it didn't cost much anyway.

**Ronny49** · #13 07-07-2011, 08:47 AM

Quote:

Originally Posted by alec

Ronny, the tech was adamant that bridge mode only applies to the top bananas, and the manual and drawing on the back of the head seem to agree. It still works from a 1/4" out, but apparently only one channel is providing the juice.

Since I was using an 8 ohm cab, I was only getting 220w which makes the low volume seem more reasonable.

It will be sweet if this unit can be fully repaired for a reasonable cost (I am getting an estimate first). If not, it didn't cost much anyway.

Well then, I have no clue about yours, but let me tell you... I tried it stereo and mono and mono was a heck of a lot louder! Mine was made in the early 90's, . So, who knows if anything changed along the way. But I know mine was bridged through the LEFT quarter jack out.

BassmanPaul · #14 07-07-2011, 11:04 AM

Quote:

Originally Posted by Ronny49

But I know mine was bridged through the LEFT quarter jack out.

I know nothing about this amp but even so, bridging through a 1'4" phone jack is highly unlikely. It's certainly something I have never seen before.

Jeff Scott · #15 07-07-2011, 04:06 PM

IIRC the Stereo 800 is the same power amp section as a SM900, basically.

**B-string** · #16 07-07-2011, 07:33 PM

Quote:

Originally Posted by BassmanPaul

I know nothing about this amp but even so, bridging through a 1'4" phone jack is highly unlikely. It's certainly something I have never seen before.

^

The 1/4" jack would HAVE to be insulated from the chassis and carry a scarry shock warning!

alec · #17 07-26-2011, 10:49 AM

I got it back today, all fixed up for $165.
I set it up in bridge mode into an 800w Labsystems quad and it sounds amazing!

T-Bird · #18 07-26-2011, 01:25 PM

Hi.

Good to hear that You got it fixed with reasonable repair bill.

What was the problem, someone may use the search function...

.

Regards
Sam

BassBod · #19 07-26-2011, 03:07 PM

Mine is bridged only through the banana sockets (using one of each pair, as I recall?). Worth checking the SWR site for a downloadable manual - its all in there.

Love mine..except the fan, when I can hear it!

BassBod · #20 07-26-2011, 03:12 PM

From the Stereo 800 manual...

To operate the Stereo 800 in the Bridge/Mono mode, the Stereo/Bridge switch should be in the "IN" position. In this mode, one set of banana jacks are provided for your speakers. These are the top two jacks indicated + and - on the back panel in the "speaker outputs" section. Next, make sure your signal source is connected to one of the LEFT speaker inputs (balanced or unbalanced). The volume in the Bridge mode in controlled by the Left volume control on the front panel. Any signal source plugged into the Right inputs will not be heard through your speakers.

Hope that helps