Sunn 190L + Custom Cab(s)

[sunnburnt]

Hello! Glad to be a part of a great community. I purchased a Sunn 190L a couple months back and I wanted to make a couple cabs for it. The head has an ohm rating of 8... and then 4 for an external. My question is, if I wanted to make an 8 ohm 2x12 and a 4 ohm 1x15 and play them together, will that work?

Thank you for your time, I really appreciate it.

EDIT: Also, if anyone out there would be willing to answer some questions about speakers for me, I'd shoot them some cash over PayPal or something.

[Walt-Dogg]

Think of the 4 ohm cab as two 8 ohm cabs in parallel. Wire that up in parallel with another cab 8 ohm cab and you'll have 2.6 ohms. What labels on your amp are actually telling you is that it's a 4 ohm minimum amp and when you use the second jack your speaker load should be no less than 4 ohms TOTAL. So what you should do is hook the amp up to two 8 ohm cabs that way it will see a safe load of 4 ohms. I don't know about doing down to two 2 though, from what I've been told tube amps don't mind a downward mismatch the same way solid state amps don't mind an upward impedance mismatch. But if the amp doesn't handle 2 ohms. Don't risk it.

[sunnburnt]

Thank you for the help! I really appreciate it. Everything makes sense now. When it comes to wattage, the back of the head reads '400 watts' when the actual wattage is 80 watts. Is that just how much I have to work with when it comes to speakers? Sorry for the potentially ignorant questions, trying to grasp this the best I can with limited research resources.

[Isaac]

Simply, 400 watts is how much the amp uses. 80 watts is how much it's capable of putting out to the speakers.

Beyond that, it gets a little more complicated. The 80 watt rating is for clean, undistorted power. If you drive it beyond that, the power output increases, but it's no longer clean. Theoretically, at a full square wave, the same amp could put out 160 watts, but I don't know that the tubes or transformers could take that for any length of time. I also don't know how much power the amp would have to consume to put out that much. Besides, Sunn amps aren't known for having a great distorted sound. Rather, they're known for being clean and loud, and taking pedals well.

[BassHog]

What is actually going on with those speaker jacks is that the 8 ohm one is connected to the 8 ohm tap on your output transformer, so only 8 ohm loads should be connected there. The 4 ohm one is connected to a completely different tap on your output transformer and only 4 ohm loads should be connected there. You cannot and should not use both at the same time. There is also a 16 ohm tap on the transformer but it is not connected to a jack, it's terminated inside the amp.

So you cannot safely run an 8 ohm and a 4 ohm cab together on this amp. You would need either two 16 ohm cabs run parallel into the 8 ohm jack, or two 8 Ohm cabs run parallel into the 4 ohm jack.

Having cabs with different quantities of speakers in each cab will cause the power to each cab to not be equal though, but people do it a the time.

[loudthud]

What is actually going on with those speaker jacks is that the 8 ohm one is connected to the 8 ohm tap on your output transformer, so only 8 ohm loads should be connected there. The 4 ohm one is connected to a completely different tap on your output transformer and only 4 ohm loads should be connected there. You cannot and should not use both at the same time. There is also a 16 ohm tap on the transformer but it is not connected to a jack, it's terminated inside the amp.

This is not true! Do a search for the word "mechanism".

Your best course of action is to build two 8 Ohm cabinets. Use an 8 Ohm 15 and two 16 Ohm 12s. Look for speakers with sensitivities in the high 90s. For power rating, look for 200W or more for the 15 and 100W or more for the 12s.

[Isaac]

What is actually going on with those speaker jacks is that the 8 ohm one is connected to the 8 ohm tap on your output transformer, so only 8 ohm loads should be connected there. The 4 ohm one is connected to a completely different tap on your output transformer and only 4 ohm loads should be connected there. You cannot and should not use both at the same time. There is also a 16 ohm tap on the transformer but it is not connected to a jack, it's terminated inside the amp.

So you cannot safely run an 8 ohm and a 4 ohm cab together on this amp. You would need either two 16 ohm cabs run parallel into the 8 ohm jack, or two 8 Ohm cabs run parallel into the 4 ohm jack.

Having cabs with different quantities of speakers in each cab will cause the power to each cab to not be equal though, but people do it a the time.

The output jacks are switched such that when plugging into both, they are both connected to the 4 ohm tap.

So one 8 ohm cabinet should be connected to the 8 ohm jack. One 4 ohm cabinet should be connected to the 4 ohm jack. Do not do these two things at the same time. But connecting two 8 ohm cabinets, one to the 8 ohm jack and one to the 4 ohm jack is fine.

[BassHog]

My bad, Isaac is correct. I forgot that they had that switching mechanism on the output jacks.