K Dumb Speaker Impedance Question for ya---go easy :)

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Mrevol

Mrevol

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So I have a VH4 and want to run two cabs. I know that if I run two 8 ohm cabs then I have to run them out the 4 ohm output of the amp. My question is I'm not a 100% on the labeling of the diezels speaker outputs. So obviously the 16ohm is for one 16ohm cab and etc.. for the 1x8=8ohm cab and 1x4=4 ohm cab. Now what if I want to run two cabs?? and what is 2x8 etc on the diezels??? Explain both a serial setup and parallel.

Might be dumb but I would rather be safe then sorry.

Thanks guys
 
On both 4 ohm outputs.
They are wired parallel.
 
Sorry Peter but little confused. :confused:

The VH4 has the following labels on the back speaker jacks.
1x4
2x8
2x16
1x8
16

So which two would I plug to run two 8ohm cabs (i know would be 4ohms) or two 16ohm cabs (8ohms)?

Hope this makes sense. :scared:
 
You have two mono cabs, 8 ohms each. Plug each cab into the taps labeled 1 x 4/2 x 8.
 
So then:
1x4> 8ohm cab
2x8> 8ohm cab

And if two 16ohm cabs then:
1x8> 16ohm cab
2x16> 16ohm cab
 
Two 8ohm cabs --> two 8ohm holes. (= 4ohm load)
Two 16ohm cabs --> two 16ohm holes. (= 8ohm load)
 
No

1x4 = 1 4-ohm cab
2x8 = 2 8-ohm cabs

1x8 = 1 8-ohm cab
2x16 = 2 16-ohm cabs

Mrevol":3hk94a6q said:
So then:
1x4> 8ohm cab
2x8> 8ohm cab

And if two 16ohm cabs then:
1x8> 16ohm cab
2x16> 16ohm cab
Click to expand...
 
I think this is getting way too complicated than it should.

As my own amp is in our rehearsal place I use a pic from Internet. This is just a webpage I found through Google's picture search:
http://www.audio-machinery.com/diezel/data/vh4/vh4.html

Take a look at the second picture from the top. In this picture we have VH4S which is stereo and that's why there is Speaker A and B sections. Forget the Speaker B outputs. If you look at the Speaker A section, your VH4 should have similar outputs, right?

Starting from the right-hand side:
1. one 16 Ohm output
2. 8 Ohm output to connect EITHER one 8 Ohm cab or two 16 Ohm cabs
3. 4 Ohm output to connect EITHER one 4 Ohm cab or two 8 Ohm cabs

As these German wonders are top-quality machines, Im damn sure that your amp will not explode if you mismatch the connections. Some manufacturers such as Mesa Boogie actually recommends trying mismatching for tonal reasons, but that is not my advice to you here. Just make sure that you always have a load (cab) connected when the amp is on and signal is fed to the amp.
 
So my post then was correct? I would also never use 2x16 and 2x8 unless running two cabs?
 
It does not make any difference wether you use the above or bellow plug-hole when using only one cab.
 
Mismatch with a heavier speaker resistance then amp expects won't kill your amp, mismatch with lighter speaker resistance then amp wants will fry your output transformer. I have a Marshall that I killed because of this. Expensive mistake. I have little doubt that a Diezel will eventually break if you did this too. The mismatching i.ak mentions for tonal reasons is always 8 ohm amp -> 16 ohm cab or 4 ohm amp -> 8 ohm cab not the other way round!

2 x 8 ohm cabs go in the 4 ohm ports. 2 x 16 ohm cabs go into the 8 ohm ports.

Maths for 1 cab is 1/output = 1/cab1 (so you put the cab in the relevant marked hole)
Maths for 2 cabs is 1/output = 1/cab1 + 1/cab2 (giving 1/4 = 1/8 + 1/8 for 8 ohm cabs, so use the 4 ohm output on the amp)

Don't use 4 ohm cabs if using more then 1, or use a serial box that can link your cabs to add their resistance together.

HTH :)
 
There seems to be a difference how sensitive the output trannies are to mismatching. I believe the ones in Diezels will be pretty tought to kill. As I am not an expert on the "law of Ohm over output transistors' tolerance" I will not comment on this mismatching towards higher or lower resistance. Nevertheless we are not talking about jumps between 32 Ohm and 2 Ohm so I doubt there's that significant issue - Esp. with Diezel in concern.

...still, personally I do not recommend nor prefer mismatching and my comment was just to encourage you that you will not brake your amp that easily. :thumbsup:


Ilkka

P.S. Greetings to fellow Blackmachiner
 
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