Question about Sentura 1 and Sunn 212LH

[JociaPark]

I just bought a Sentura 1 head and a Sunn 212LH and I'm curious on how the impedance will match up. The oldest amp I've ever owned was a JCM800, so I'm not really familiar with older amps or pretty much anything other than a Marshall. So obviously there isn't an impedance selector switch on the Sentura, so I'm assuming that it puts out 16 ohms or possibly 8? The system impedance is only 8 ohms on the Sunn 212LH cab, so how would I go about this?

[Isaac]

Normally on Sunn amps, the output jacks will be labeled something like SPEAKER 8 OHMS and EXTERNAL SPEAKER 4 OHMS, or the numbers might be 16 and 8. If you have an 8 ohm speaker, plug it into the 8 ohm jack. If you have a 4 ohm speaker, plug that into the 4 ohm jack. If you have two 8 ohm speakers, plug them into both jacks.

If they aren't labeled, we'll need to dig a little deeper.

[JociaPark]

I actually bought the Sentura head off of ebay, and I haven't received it yet to really examine it. Based off the pictures however, it doesn't seem to label how many ohms it puts out. Here's the link: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=280322372835

[loudthud]

Looking at the pictures on the ebay auction, your amp has the sticker but there is no impedance marked on it. You need to look inside the amp and determine what color the wires that go to the speaker jacks are. This can be dangerous so don't do it if you are not familiar with the hazzards that are present. You could electrocute yourself. Refer service to qualified personel.

Look at this thread:

http://sunn.ampage.org/sdp/index.php/topic,3833.0.html

I think the colors on your transformer should be the same as described in the above thread.

[Isaac]

Here's another thought. The Sentura I was sold with a Spectrum I bottom, which contained one JBL D130, later with a D15S. I think it highly unlikely that either cabinet had a single 16 ohm driver in it. I'm as sure as I can be that the Sentura I is an 8/4 head.

However, opening it up and looking is still the best answer. Yellow wire is 16 ohms, orange is 8, brown is 4.
http://sunn.ampage.org/site/schematics/sonici-40.gif
Yes, I know this is the schematic for the Sonic I-40, and not that for the Sentura I, but the same transformer was used, I'm sure.

All it takes to open it up is removing the four screws on the back, then the four on the bottom. Remove the back panel. The chassis then slides out. You don't need to touch anything inside the chassis, just look at the colors of the wires attached to the output jacks.

Some people worry about the filter caps storing lethal voltages. I've never got a serious jolt from an amp that had been turned off and disconnected from the wall for any length of time. If you're worried about that, turn it of and unplug it overnight, and don't touch the cap terminals.

[JociaPark]

I opened the amp up and it looks like there are two yellow wires, one orange, and one black wire all connected to the speaker jack area while the brown wire is connected to something else. So would that mean the Speaker jack is 16 ohms, and the EXT Speaker is 8 ohms? I can post pictures at a later time. I'm not really knowledgeable in this area, so the schematics aren't helping me too much..

[loudthud]

The brown wire is the 4 ohm tap so it sounds like your amp is wired for 8 and 16 ohms. IIRC the D15S I have is 16 ohms. It has a rotted cone so I've never hooked it up to anything.