Stereo Chorus 400 and 4x12 cab questions

[Scott_Krieger]

Hi!
New here and looking for suggestions on a stereo 4x12 cab I want to build. I have a chance at the amp section of a rebuilt Stereo Chorus 400 combo for cheap (not the Power Pak) and want to convert it to a head (like the Power Pak lol) and use it with a 90's era 4x12 cab that was given to me free, less speakers. The SC 400 has output of 4 ohms per channel and the 412M stereo cab jack plate says mono 16 ohm and stereo 8 ohm per channel.

Should I look for 8 ohm speakers and wire each side in parallel for the 4 ohm load per side or 16 ohm speakers to get 8 ohms per side? I know the 4 ohm load will present the matched impedance to the amplifiers of the head and 8 ohm will be safe, but probably with less overall volume. I'd like to get the full 200 watt output the head offers.

The cab originally had Sheffield's in it and I am not sure what I want to reload it with. Same seller says he has some Scorpions for sale too.

Any advice appreciated fellow Peavey enthusiasts!

[JamesPaul]

Welcome to the forum.

To get the rated 200 watts, you will want to use 8 ohm speakers. Then when the cabinet is set to Stereo, each side will be the two 8 ohm speakers in parallel for a total 4 ohms each side. If you switch the cabinet to Mono, it should connect the two 4 ohm sides in series for a total 8 ohms. If you do this, put some tape over the jack plate labeling and write in the updated 8 ohm Mono, 4 ohm Stereo.

If instead you want to use 16 ohm speakers, it will still work. It just will deliver less than the rated 200 watts to the 8 ohm Stereo sides.

If the 8 ohm and 16 ohm speaker efficiencies are the same, the 8 ohm speakers will yield more volume than the 16 ohm due to more power being delivered to the 8 ohm configuration.

[Enzo]

And really the difference is only 3 decibels. If you already have 16 ohm speakers, pairs of them is an 8 ohm load. The amp will be perfectly happy at 8 ohms, and the difference between 130 watts and 90 watts is hard to hear. SO you can use either 16 ohm or 8 ohm speakers. 8 ohm speakers makes a pair of 4 ohm loads for max power, but really 16 ohm speakers will be plenty loud too. In other words in my view use the speakers you like best rather than worrying about the last few watts.

REad the specs carefully. The amp can put out 200 watts, but that is total for two channels. When both channels are driving you get 200 watts total or 100 watts on each side. If you use ONLY one side it can produce 130 watts in that channel. All that into 4 ohm loads.

[Scott_Krieger]

Thank you for the replies and great suggestions. I was planning on using a label maker to relabel the input ohms so as not to confuse myself or anyone after me.

I am going to look at the SC 400 head and Scorpion speakers this afternoon. I'll post back what I find!

[Scott_Krieger]

Thanks for the awesome replies! I will check out the scorps and it seems that pairing down to 8 ohms is probably what I will end up doing just so I can get this rig up and running. I am also going to look at an older cab this weekend that is a 412s has a serial of 1E-862278

From my research here, I am thinking that's a 1981 model unless they built these in the 79's.

[Scott_Krieger]

Update: So I bought the 2 Scorpions (serial numbers were within ten production units) and found another one locally on Craigslist for $35 in good shape. One more Scorp and I will be able to load this cabinet after I redo the Tolex. Can't wait to fire it all up and see how it sounds and how loud it cranks!