Ohmage is a nightmare.

[sambo]

Ok chaps, here's one for you.

My mate's Marshall TSL is a 2x12 combo. Now I want to use it as an extension cab for my ENGL Screamer just to see what it sounds like.

The ENGL has (in terms of outputs):

8 Ohms Parallel;
1x8 ohms
2x16 ohms

OR

16 Ohms Serial;
1x16 ohms
2x8 ohms



Now, the 2 speakers in the Marshall are wired together it seems as there is only one jack connected at the back.

It is connected to the "4 or 8 ohm parallel" output jack, (of which there are two), and there is a switch (4 or 8 ohm), currently set to 4 ohm, next to it.


Now, does this mean that I take the lead of the two speakers (which is 1 singular lead remember), and put it in the 8 ohm parallel on the ENGL (after unplugging the internal combo speaker of the ENGL of course)? Or what? Man, I hate amps.



Thanks for any help on this,


Sam.

[HTH AMPS]

so the Engl only has the ability to run 8 or 16 ohm loads is what we're saying.

If the Marshall currently has two speakers and they're set to 4 ohms, they must be two 8ohm speakers wired in parallel.

To run your head with that cab, you'd have to rewire the two 8ohm speakers in series to give 16 ohms.  However, then you wouldn't be able to use it with the existing Marshall amp (you said the Marshall only has settings for 4 and 8 ohms, right?)

In short, there is no plug-in-and-play option for you with the Marshall cab and the screamer head.

[sambo]

Ah, the Marshall also has a singular 16 ohm output if I remember correctly.

But if the Marshall can run in 8ohm parallel at the flick of the switch (at least I guess it does), does that not mean I could go hook up the speakers to the 8ohm parallel output of the ENGL?

See the confusing thing is, the Marshall has TWO outputs under the branch of "4 or 8ohm parallel", but is only using one for both of the speakers. The ENGL also has two outputs under the branch of it's equivalent; "8 ohm parallel", but is using it for ONE speaker.

Is that just stating the obvious and basically I should re-read your post again? :lol:


Damn I am SO confused. :?

Oh, and I forgot to mention, the ENGL is a combo as opposed to a head. Missed that out of the first post. Not sure if that makes a difference.

[sambo]

Ah wait a minute, I'm being an idiot.

The switch is if I wanted to use 2x16 ohm speakers in parallel right?


So the speakers currently in there, are 2x8 ohms, running in parallel?

So I would need a 4ohm parallel output on the ENGL?

[Henk]

You need to check the speakers first, it is not unlikely they are 16 ohm speakers in the marshall but the marshall is just set wrong, ive seen that before on stock combo's.

If the speakers are 8ohm parallel the load is 4 ohm or in case of 16 ohm speakers, 8 ohm load.

If you want to run two speaker outputs on your amp the load has to be matched, so both need to be 8 ohm, at least i think the screamer single speaker has an 8 ohm load right?

Then you need to use a 2x8ohm speaker output on you screamer to run both loads, IF offcourse both ARE 8ohm loads. The amp has to be set at 4 ohm in that case if you have a selector like that. Its in the manual how to run two cabs on your screamer.

Mixing two cabs of which one is the 'wrong' load is about the worst thing you can do by the way, dont do it......

Alternative is just to try the screamer on a 4x12 cab somewhere in a shop or whatever :idea:

[Twinfan]

It looks like the output on the Marshall is currently set wrong.  It should be on 16ohms as a stand alone combo - I'd get your mate to change it ASAP!  Here's why:

Combo alone
Two 8ohm speakers in series, 16ohm load
Plug speaker lead into 16ohm plug

Combo with TSL extension cab
Two 8ohm speakers in series in the combo, 16ohm load
TSLC212 extension cab, two 8ohm speakers in series, 16ohm load
Plug both in, set amp to 8ohms.

Running a 16ohm output into a 4ohm load, as it is now, is asking to blow the output transformer!


Here's what you can do to run your Engl through the Marshall:

You could plug the lead from the Marshall speakers into the 16ohm socket on your Engl and use it as a 2x12 cab.  Or, you could plug both the Engl AND the Marshall speakers into the 8ohm  parallel (left hand) outputs on your combo and run all three speakers at the same time.


For reference, here's the info from the Marshal TSL122 combo handbook:

3 & 4. Loudspeaker Outputs & Impedence Select

There are three loudspeaker jacks provided on the TSL amps. One is
dedicated to 16 Ohm use only and is marked as such. This is for use
when using either a single 16 Ohm cabinet (Marshall 4x12” of course!)
on the TSL100 head or the internal speakers on the TSL122 combo.
Using this socket negates the use of the other sockets! The other two
sockets are marked 4 & 8 Ohm Parallel Jacks and are connected to the 4
& 8 Ohm Impedance selector. These are used when using either non-
Marshall cabinets of a different impedance (either 4 or 8 ohms) or when
using multiple speaker systems (i.e. when using two stacked Marshall
4x12” cabs or when using an extension cab with the TSL122 combo).
Remember to set the Output Selector to the appropriate setting! (item 4)
i.e. 2 x 16 Ohm loads = 8 Ohms, 1 x 4 Ohms = 4 Ohms, 2 x 8 Ohms = 4
Ohms. If in doubt consult your Marshall dealer.

WARNING! - Under no conditions operate your TSL amplifier without a
loudspeaker type load connected, otherwise costly damage may result!
You may notice that the TSL122 2x12” combo has two different types of
loudspeaker (1 x Marshall Celestion Vintage and 1 x Marshall Celestion
Heritage), this is because combining the characteristics of the two
speakers helps reproduce the unique tone capabilities of this amp. We
care about your tone!

To further extend the TSL122 combo’s capabilites there is a matching
2 x 12” cabinet - the TSLC212. This cabinet is the perfect match for the
combo as it features a similar speaker configuration.

[sambo]

Crikey, thanks guys. Just got a whole load more confusing!


Ok so... Dave; is it possible that the Marshall speakers are wired in parallel (for some odd reason), or something, and that's why it is set the way it is?


I'll ask my mate whether he as ever plugged/unplugged the speaker jack to see if it perhaps was originally in the 16ohm.


Anyway, this:

You could plug the lead from the Marshall speakers into the 16ohm socket on your Engl and use it as a 2x12 cab. Or, you could plug both the Engl AND the Marshall speakers into the 8ohm parallel (left hand) outputs on your combo and run all three speakers at the same time.

.... was a godsend. Even I understood it.   :oops:  :)


Oh and Henk you just reminded me to check the ENGL manual. Doh! :oops:

[Twinfan]

Ok so... Dave; is it possible that the Marshall speakers are wired in parallel (for some odd reason), or something, and that's why it is set the way it is?

If your mate has owned it from new, then no.  If it was second hand, you'll need to check if they're the original 8ohm speakers or not, and how they are wired.

I'll ask my mate whether he as ever plugged/unplugged the speaker jack to see if it perhaps was originally in the 16ohm.

I'd ignore how it has been, and do what I've said above to check it's set correctly now for the speakers/wiring it has in it  :)

[sambo]

Okay dokay, will do.


I know he's owned it from new. But it was bought from a little guitar shop (not the internet or a big dealer or anything), which I thought COULD possibly mean that one of the employees had put the lead in the wrong jack after it came out or something along those lines.



How can I check how the speakers are wired? Or more accurately; how will I tell how it's wired (assuming I'm look at the wires)? If that makes sense... :? :lol:

[Twinfan]

He's had it from new - it'll be wired as 16ohms.  Get the jack swapped over  ;)

[sambo]

:lol:


Ok I swapped it to the 16. Fired up the amp desperately hoping it wouldn't blow up in my face... hoorah! :lol:


Ok now the big test. I'm gonna run the Marshall speakers with the ENGL. So for all three speakers, it's Marshall lead into the 8ohm parallel jack, alongside the ENGL speaker in the other 8ohm parallel jack?


The one remaining confusion though; the internal combo (ENGL) speaker, must be 8ohms if it's running the 8ohm parallel jack by itself right? But I thought the Marshall speakers was a 16ohm load... so.... why does the Marshall go into the 8ohm parallel with the ENGL speaker?

Sorry if that's just a stupid question.

[sambo]

Two quotes from the ENGL manual:

"Poweramp Output 8 ohms parallel: Parallel 8-ohm speaker outs, connected
internally in parallel. Connect an 8-ohm cabinet or, in the case of the Combo E330, its internal
speaker here. Alternatively, two 16-ohm cabinets can also be connected to these two outputs."


AND



"Poweramp Output 16 ohms serial: 16-ohm speaker out, connected internally in series
with Jack 28. Connect a 16-ohm cabinet here. Two 8-ohm speakers are connected to Jacks 27 and
28, for example a combination of the internal 8-ohm speaker of the Combo E330 and an external
8-ohm cabinet, e.g. the ENGL models E112 or E412.
CAUTION: If you intend to use a 16-ohm cabinet only, make absolutely certain you
connect it to Jack 27. Jack 28 is only enabled when a speaker is connected to jack 27."




So, I could run the Marshall very simply as a 2x12 WITHOUT the internal ENGL speaker using jack 27. That's what you said before. :oops:


But all three... I'm still not understanding that one.


Thanks very much so far by the way!

[Twinfan]

Sorry Sam - I thought your internal speaker was a 16ohm?  If it's 8, then you can't use all three speakers.  Sorry  :oops:

[Henk]

You should A) check all speaker ohmages, B) figure out if the TSL is serial or parallel wired.

Thats all you need to know!!!!!!

Most 2x12 combo's have 2 16ohm speakers wired in parallel making a 8 ohm load. If there are 8 ohm speakers and they are wired in a loop(serial) it is a 16 ohm load. Check for pictures of both wirings on the internet, parallel wiring is with both wires to one speaker and then to the next, serial is one wire to both speakers and then a return making a loop so to say. Im not sure if i explain this correctly in english though :oops:

Keep in mind when you connect 2 8ohm cabs to an amp your amp needs to put out 2x 8ohm power out wich is a 4ohm setting. Probably that is what is confusing to you, 4ohm is twice as much power as 8ohm(and 8ohm is twice as much as 16 ohm). Thats also why its very risky to set the wrong output ohmage on your amp.

At least thats how i understand it.

[Twinfan]

Most 2x12 combo's have 2 16ohm speakers wired in parallel making a 8 ohm load.

Henk/Sam - please check my quote above directly from the Marshall TSL manual.  The TSL122 combo Sam's mate owns has the speakers wired for a 16ohm load.  This is the standard Marshall practice.  Other manufacturers differ of course.