OHM's question RE: Sunn 610L Concert Lead Cab

[zipron7]

Hello ! I have a '68'/69 Solarus head with (2) speaker out jacks marked: (1) 16 ohm, and (2) 8 ohm ext... can I use this head with an early silver-grill Concert Lead cab marked 610L 6 ohms ? If so, which speaker jack do I use ? I've never heard of a 6 Ohm cabinet... Does anyone know what kind of speakers are in this cab ? Does Sunn make Sunn Transducers, or does someone else ?  
Great site, thanks !

[Isaac]

You could probably use it with the 8 ohm jack, but I wouldn't recommend it. Bettr to use a 4 ohm output.

The transformer has a 4 ohm tap. Have someone who knows what they're doing wire you up for 8/4 instead of 16/8, or install an impedance selector switch.

[JoeArthur]

A 6 ohm speaker load will be equally at home with either a 4 or 8 ohms setting on the amp... it's not that much of a mismatch either way for a tube amp capable of either setting, and a solid state amp pretty much won't care - most are capable of going to 4 ohms anyway.

One thing to remember about speaker ohms... they are all "nominal", sort of like an average.  Any given speaker or speaker cabinent will vary from "nominal" throughout its range, either plus or minus and at factors deviating from nominal that you won't believe.  It would be a mistake to believe the ohms rating on a speaker is an absolute value.

If you're able, switch between 4 and 8 ohms and leave it where you think it sounds best.  

It makes for an interesting and additional "tone switch". Some "bow-teak" amp makers claim this capability as a feature!!

[zipron7]

Thanks for the quick replies, guys !
I'm reluctant to have my Solarus head modified in any way because it's in such amazing original condition, so maybe I'll just try running the 610L 6 ohm cab from the 8 ohm ext plug.
This brings up another question, tho'... can I use the 8 ohm extension cab plug without anything being plugged into the 16 ohm main speaker plug ?
I don't want to do anything that could hurt the amp....  thanks again !

[Isaac]

Yes, you can.

The way the old Sunn speaker jacks are wired, the 16 ohm jack is connected to the 16 ohm tap of the transformer. The 8 ohm jack is connected to the 8 ohm tap, and is a switched jack. When you plug into the 8 ohm jack, the 16 ohm jack is disconnected from the 16 ohm tap and connected in parallel with the 8 ohm jack, so both jacks are then connected, in parallel, to the 8 ohm tap.

In short, there's not a thing wrong with plugging directly into the 8 ohm Extension Speaker jack.

[Paul of the Bastards]

I have wondered about this.. so does this mean both jacks would then be running at 8 ohms and you would be able to hook the other input (that was originally 16 ohms) up to an additional 8 ohm cab?

[Johnny]

I have wondered about this.. so does this mean both jacks would then be running at 8 ohms and you would be able to hook the other input (that was originally 16 ohms) up to an additional 8 ohm cab?

No, they are parallel so the total load should be 8 ohms, 2 16 ohm cabs or 1 8 ohm cab. But I'm sure many have run 2 8 ohm cabs from their Sunn heads without hurting anything. If you want to do it right though, it's a pretty easy soldering job to use the 4 ohm tap on the outputs.

[pickinatit]

I have wondered about this.. so does this mean both jacks would then be running at 8 ohms and you would be able to hook the other input (that was originally 16 ohms) up to an additional 8 ohm cab?

No, they are parallel so the total load should be 8 ohms, 2 16 ohm cabs or 1 8 ohm cab. But I'm sure many have run 2 8 ohm cabs from their Sunn heads without hurting anything. If you want to do it right though, it's a pretty easy soldering job to use the 4 ohm tap on the outputs.

I would think that running the 2  8ohm cabs without rewiring to 4 & 8 outputs would depend.  If you were gigging with this amp and going to be running for long periods of time at high volume, you know, really pushing it then a 4 ohm load to an 8 ohm tap might not be such a good idea.  But if you are playing at home or mostly at moderate levels for not such a long time it probably wouldn't hurt anything.

Zipron 7,   Having the outputs switched to the 4 & 8 ohm taps, well, I wouldn't consider that a modification.  The amp was made to accomodate that configuration so I don't think that would have any negative effect on your amps value down the road (besides you can always switch it back).  I don't think that future buyers/collectors would be dissuaded by that in any way.  Just my $.02

If it was me,  even though I only baby my Solarus at home I think I would have the outputs switched to the 4 & 8 ohm taps  to play thru the 6 ohm cab, but that's just me.