Tube Amp Archive

Hi all,

I'm a little lost and confused about a couple of things with my new amp. I'll explain the situation and really hope some of you can help me out. Essentially, I bought a pre owned Dr Z Maz 38 NR with two 1x12 cabs. This is the exact amp i bought:

http://www.cranesmusicstore.com/drz...ned-p-3532.html

Essentially one of the cabinets has a mod on it, an output jack specifically. That allows me to connect a speaker cable from the Head of the amp to the Cab and then another speaker cable from the same cabs output jack to the second Cab. Having contact DR Z he advised this was a MOD made outside of his factory and couldn't comment. I would really like to wire the cabs as DR Z has stated on his website with a Y Cable in Parallel connected to the 4 OHM output and then the two male jacks going to the two 8 OHM cabinets.

I purchased a cable this evening online to be able to do this but afterwards was concerned when i was thinking that this modded cab might have been rewired in Series. Essentially, i'm looking for some advice on what do. Without knowing if the Cab is rewired, could an output jack like the one i'm describing just be added to the Cabs original circuit as an extra? or would it have to be wired differently. And secondly would the Y cable option i described above still work fine or not? I've connected some images of the output jack below. Any help would be absolutely brilliant as i'm at a loss!

http://i44.photobucket.com/albums/f2/ti ... age-3.jpeg

http://i44.photobucket.com/albums/f2/ti ... image.jpeg

thanks so much, i hope that all makes sense!

I can't see your photos, but unless they are shots of the jack wiring they won't be any help. The question you need to answer is simple: when you daisy-chain the cabs together do they connect in series or parallel? If you have an ohm meter you can answer this question easily by plugging a cable into cab #1's input and measuring the resistance from tip to sleeve on the other end, and then connect a cable from cab #1's "output" to cab #2 and measure the resistance again to see what happened. The DC resistance you measure will be a bit less than the true impedance, but close enough to tell.

Thanks for your informative reply!

I'm not sure i have an ohm meter but i can certainly check to see if my parents have one. I've re attached the images now so you should be able to see them!

OK ... that looks like a parallel jack was added to one cabinet so the two cabinets could be daisy chained ...


one speaker cable connects between the head and the modified cabinet ...

the second speaker cable connects from the 'added jack' to the second stock speaker cabinet ...

But whether it's wired correctly or not that's the question ...

You could plug into the stock jack on the modified cabinet briefly touch a 9V battery across the 1/4" jack battery + to the tip and watch to see if you can see whether the speaker moves in or out ... do the same thing with the added jack ... it should move the same way if it's wired in phase ... then check the stock cabinet

Brilliant, thank you Rock Mumbles, would it be possible this could also be a series output jack and the speaker has been rewired? or is it more likely that it's an added jack to the parallel circuit so it can be daisy chained?

I think what i'm looking to find out is if i simply ignore this added output jack (pretend it's not there), purchase a Y cable in Parallel as suggested by DR Z's website and plug the Y cable into the head and the two male jack jacks on the Y cable into the standard cabinet jack inputs would this work? essentially doing it the proper way it should be done.

Dr Z description is:

How do I run an extension cab with my combo or hook up 2 speaker cabs to my head?

This is an easy procedure. First thing to do is get a quality Y Cable like the ones offered by Procables N Sound. These cables are available in series or parallel wiring. Always match the ohm rating of the extension cab to the ohm rating of your combo speaker. The same goes for running 2 cabs.

Here's an example for parallel (the most common) connection:

1.) Disconnect your 8 ohm combo speaker form the back of the amp chassis and plug it into the Y cable.

2.) Plug the extension cab into the Y cable. You now have two 8 ohm loads in parallel to make a 4 ohm load.

3.) Plug the Y cable into the 4 ohm speaker out on the rear of your amp.

Series connection is the same except that two 8 ohm loads make a 16 ohm load. Not all Z amps have 16 ohm speaker outs so be sure to check your specific amp


thanks so much!

http://i44.photobucket.com/albums/f2/ti ... G_3426.jpg

http://i44.photobucket.com/albums/f2/ti ... G_3423.jpg

http://i44.photobucket.com/albums/f2/ti ... G_3420.jpg

http://i44.photobucket.com/albums/f2/ti ... G_3419.jpg

http://i44.photobucket.com/albums/f2/ti ... G_3418.jpg

http://i44.photobucket.com/albums/f2/ti ... image.jpeg


http://www.youtube.com/watch?v=0P0fXeFT ... e=youtu.be

Here is a video also that i made aswell. it's far more clear from about 30 seconds in.


Here are some further images of the wiring. hopefully this might clear things up a little!