SUNN Concert Bass late 70's 200 watts at ???ohms?

[knw]

So I got the later 70's sunn concert bass with the red knobs as you can see in the pictures.



I've done extensive research on the head trying to find out at what ohmage does the head put out 200 watts.

Now from my research lots of people seem to think it's 200 watts at 4 ohms and there is also lot of people saying that it puts out 200 watts at 2 ohms.

The thing is I have the matching unloaded cab and that cab is rated at 160 watts with 4 ohm resistance.

Now the reason I'm asking this is cause I wanna load that cab with a pair of eminence basslites rated at 4 ohm each I would wire them in parallel to get a 2 ohm cab.

I'v been running this head for about year now with a 8x10 svt 4 ohm cab and it's been working fine...but I would wanna run it at it's full potential and I'm assuming that would be 200watts at 2 ohms.

Now I know there is an earlier version of this head that came with a distortion knob but it only puts out 150 watts at 4 ohms. (can't go to 2ohms)

I just need to get this clarified once and for all.

So has anyone that owns/owned this head had the chance to run it at 2 ohms and if so were there any problems.

Thanks.

[loudthud]

Looking over some schematics I have there was a change made around August 1975. Earlier models had the bridge circuit with a single 3400uF 75V filter cap. After that, the output transistors are configured as a parallel totem pole with two 6800uF 63V filter caps. Both versions use the 10 wire driver transformer. The earlier power transformer has 8 wires, the later version only has 5 wires. I realize this doesn't answer your question but maybe someone has additional info. I'm not finding any Concert schematics dated later than 1975. Can you look inside your amp for a date or take a picture? Yours has a bigger heatsink than earlier models.

[pickinatit]

I have the Red Knob Concert Bass Amp.  When I first got it someone on here
(& I think it was Ed Bass) suggested that it was not a good idea to run this amp at 2 ohms even though Sunn rated them for that resistance.  Had something to do with the # of circuits or something I'm not going to pretend to understand.  Maybe Ed or someone else will chime in with the explanation.
I'll look for the thread but have much time now.  It goes back to late 2006 I think.

[EdBass]

That was Joe Arthur. I'm not real hip to Sunn transistor gear, more of a tube kinda guy. His answer makes sense to me though!


http://sunnforum.ampage.org/index.php/topic,3189.msg9845.html#msg9845

[pickinatit]

Yeah, that's the post I was talking about.  Thanks Ed.
To make it even easier, here's the part of Joe Arthur's post that I was referring to:

"The later models are rated at 200 watts, probably achieved by a 2 ohm load.  Concerts prior to that are rated at 150 watts into a 4 ohm load.

For what it's worth, I would never drive a 4 transistor output stage into 2 ohms, especially 2N3055s which is what both early and late models use. Most transistor power amps capable of "easily" driving a 2 ohm load will have at least 6 if not 8 output transistors capable of handling the increased current.

It is simply not worth the extra 50 watts, which you probably won't even notice... to the life of the output stage.

But that's just me.  I would rather have an amp that will survive easily at 150 watts over taking a chance at 200 watts and failure.

There are other problems with running at 2 ohms, but I am too lazy to list them now.  Your mileage may vary."

[vwcsonic]

Hi new guy here. Just got ahold of an old Sunn Concert Bass. The poor thing had been neglected for years, rust on parts, noisy pots/switches--total mess. Took it home and cleaned her up. Now it sounds great. The Distortion doesn't work, and the "Treble Boost" switch is dodgy, but don't like that anyway. Most important question is that upon opening up the head floating around inside were two capacitors. I've included photos below. One still has bare wire leads on it. The other had a single insulated lead and that broke off.

Anyway, wondering where they belong. The amp sounds fine, but would like to have these wired back in if they are necessary components. One I know came from the area near the Polarity switch, and there seems to be a bare wire sitting there that may have once connected to it. The other I have no idea. Any help would be welcome. As I'm a repair idiot, please be sure to include tips like--don't touch "xxx" while working or you will die.

By the way all the pots cleaned right up and sound quiet now. Plugged it in and wow!--just sounds great. Amazingly loud into a 4ohm 2x12 cab with Fane speaks. (yea I'm a guitar player, but my P-bass sounds great with this. Guitar not so great.) Thanks. PS: Is the distortion on these worth the trouble of trying to get it working??

[Isaac]

In my opinion, the distortion isn't worth much. I never cared for the sound of it.

[mckinnon audio]

Hi there,those caps most likely came off the polarity switch,going to ground,that's why the amp still works with them "missing". Good luck,Mel.

[Greg_M]

Run the two speakers in series @ 8 ohms and be safe

[apewizard]

I recently acquired a red knob version and I'm just wanting to know whether I can run this head through an Orange 2x12 with vintage 30's (120watt cab in total), or is the 200 watt load too much for a 120 watt cab to handle?

The cab is currently wired to 16 ohm, but I was thinking of wiring it to either 8 or 4 to accommodate for this head. What would be the best OHM to wire the cab to for this head, to attain maximum volume, or should I just try a different cab/speakers?

[matto)))]

is the 200 watt load too much for a 120 watt cab to handle?

i think orange amps and celestion speakers follow a european wattage rating.  now im not sure what the american wattage would be, but my tech told me that it's roughly double the european amount...so your cab may be around 240 watts or so.  that orange cab will be more than enough to handle your concert bass though

and i think that you could only rewire the speakers to a 4 ohm load

[apewizard]

Thanks for the info Matt!

[mckinnon audio]

  Hi there,as long as I can remember,a watt is a watt,there is no European or North American watt ratio.An amp that puts out 100 watts rms is a 100 watt amp,regardless of where it was made.

[biltmore]

Hi there,as long as I can remember,a watt is a watt,there is no European or North American watt ratio.An amp that puts out 100 watts rms is a 100 watt amp,regardless of where it was made.

Indeed.