What ohm speakers do I need to buy for my cabinet?

[hdrive25]

Hi,

I’d like to build a 4x12 speaker cabinet to stack my 100 watt Marshall TSL 122 combo on top of and I’d like to confirm what I need for speakers before buying them.

Currently the combo has 2x12 Celestion speakers, a Heritage and a Vintage both of which I believe (I think) are 16 ohms and are plugged into 1 of three Loudspeaker outputs. They are plugged into the 16 Ohm Only output jack.

Question: What ohm speakers do I need to build my cabinet? How would I plug the 4x12 cabinet into my TSL122 so that all 6 speakers are utilized?

See the back panel of my TSL 122 on Page 29 of the following link.

http://www.marshallamps.com/handbooks/pdf/tsl100.pdf

Thank you in advance,
JP

[loudthud]

Thanks for posting the link to the user manual. There is a small problem with connecting a 4x12 to this combo. In one case, you can match the total load to the amp but the individual speakers in the 4x12 will only be receiving half as much power per speaker as the speakers in the combo. In the other case, each speaker will receive equal power but the total load will be 5.33 ohms connected to the 4 ohms tap.

In the first case, your 4x12 cabinet should have 16 ohm speakers wired for a total cabinet impedance of 16 ohms. Plug the internal speakers and the extension cabinet into the 4/8 ohm jacks and set the switch to 8 ohms.

In the second case, your 4x12 cabinet should have 8 ohm speakers wired for a total cabinet impedance of 8 ohms. Plug the internal speakers and the extension cabinet into the 4/8 ohm jacks and set the switch to 4 ohms.

[pdf64]

Your amp can drive pretty much any load, so for another cab I would get the same impedance speakers that are in the combo (confirm what they are first), then that gives you the option of swapping them around.

[Jazz P Bass]

Marshall 4x12 wiring

Here is how Marshall wires the 4x12 cabinet

[hdrive25]

Wow! Boy I am glad I found this forum! Thank you very much for the replies.

Am I trying to do something that does not make sense? I'd like for all six of the speakers to output the same volume. Loudthud, Does this mean I should select the second option? If I select the second option, will the amplifier still produce the same full volume levels as with the 2x12 alone? The reason why I'm adding a cabinet is because I am looking for the closed cabinet thump frequencies.

JP

[hdrive25]

I had another guy send me this reply . . . .I'm still trying to add all this together . . . I think I can buy 4 12 inch 100 watt 16 ohm speakers and I should be able to have all six speakers working together . . . .Does this make sense?

The two 8 ohm outputs are wired in parallel to the 8 ohm tap of the amp's output
transformer. This allows you to drive two 16 ohm loads at the same time
using both jacks (total load 8 ohms in parallel). Since you have a 16 ohm
cabinet, you should build the 4x12 cabinet to also be 16 ohm this way you
can plug both cabinets in the 8 ohm outputs and it'll work great. I hope
this message helps and please feel free to contact me again with any
questions or comments.

[Chuck H]

The option you propose is one that loudthud already suggested. It will work fine for the amp but won't power every speaker equally.

According to your manual the speakers in your amp should be two 8 ohm speakers wired in series for a total load of 16 ohms.

The only way to power all your speakers equally would be to run them equally. That is: all in series, all in parallel or three sets of two series wired speakers run in parallel to the amp.

The last one may be your best option and was also proposed by loudthud. 5.33 ohms on the four ohm tap is fine. And to use the combo by itself you would plug the internal speakers back into the 16 ohm tap.

All this provided you do have two 8 ohm speakers in the amp now. If you do have 16 ohm speakers they are wrong for that amp and should be replaced or run in parallel on the 8 ohm tap and would negate the above proposed wiring scheme

Chuck

[loudthud]

If I select the second option, will the amplifier still produce the same full volume levels as with the 2x12 alone? JP

Overall, your amp will be louder with the 4x12 connected. Probably a slight advantage to the first option, but not much. ( I'm assuming the speakers you select are of comparable effeciency to what's in the combo.) If you stand back 20 feet from the stack, you generally perceive the combo to be louder than the 4x12 because the 2x12 is on top. With a straight front 4x12, more sound goes to the audience, and there is a little less on stage. This can be a good thing. The sound goes past you below waist level. With a slant front 4x12, stage volume can be higher than you would really like, especially as you move towards the stack.

[hdrive25]

ok . . . I've heard both now and need to confirm. Are the two 8ohm speakers in my TSL 122 Combo wired in series or wired in paralell? If they can be plugged into one of the two 8 ohm paralell jacks does this mean they are wired in parallel for a total of 8ohms?

[Chuck H]

ok . . . I've heard both now and need to confirm. Are the two 8ohm speakers in my TSL 122 Combo wired in series or wired in paralell? If they can be plugged into one of the two 8 ohm paralell jacks does this mean they are wired in parallel for a total of 8ohms?

No way for us to know. We don't have the amp to look at and my clairvoyant skills are a little off today

Seriously, those are after market speakers so I don't know what ohmage they are or how they're wired up. You said before that they were 16 ohms and plugged into the 16 ohm jack. If this is true it would mean your amp has been running into an incorrect impedance.

If you have two 16 ohm speakers they should be run in parallel and plugged into the 8 ohm jack. If you have two 8 ohm speakers they should be run in series and plugged into the 16 ohm jack.

You can run six speakers on the amp and have them all recieve the same power by using three sets of two speakers (one in the combo and two in the 4x12) wire each set in series and then parallel the three sets at the amps output.

If you have 8 ohm speakers in the amp now you need to get 8 ohm speakers for the 4x12 cab and plug the internal speakers and the 4x12 cab into the parallel outputs set at 4 ohms.

If you have 16 ohm speakers in the amp now you need to get 16 ohm speakers for the 4x12 cab and plug the internal speakers and the 4x12 cab into the parallel outputs set at 8 ohms.

Either way wired as described above.