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Post subject: Mustang V not working with my 2x12 cab...
Posted: Tue Mar 01, 2011 7:49 pm
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I just bought me a Mustang V and right out of the box I plugged in into my Jet City JCA 24S, made sure the cab was switched to stereo (2x16 ohm), and turned the head on. When I turned it on I got this very loud sound like a helicopter landing in my living room even with the master volume turned all the way down. I did a quick test seeing how each side of the amp worked with each side of the cab and tried each side plugged into the cab switched to mono and those all worked alright, but with it plugged in in stereo as it's supposed to run I just get the chopper sound.

I took my setup into the dealer that sold me the Jet City cab thinking it might be the defective piece. We tried other heads in the store through my cab and they worked fine. We then tried my head through another Jet City cab, this one was the 4x12 cab that can run in 2x8 ohm stereo mode like the Fender Mustang cab, and we got the same chopper noise through the 4x12 cab. I concluded that it was a problem with my head, so I took the Mustang back to my local Fender dealer and they swapped it for a new one thinking this one was defective. I hooked the new one up and got the same thing.

Before I purchased my setup I emailed Fender directly and asked them if this setup would work fine because in the manual the way it's worded it makes it sound like the Mustang head can ONLY take an 8 ohm load... The response I got from Fender when I asked about using just a 2x12 cab at 16 ohm on each side was that because it was a solid state amp 8 ohm was just the minimum and a 16 ohm load would be fine, the output volume would just suffer some. I assumed this already but just wanted verification before buying the setup.

My plan originally was to start with this one Jet City 2x12 cab and eventually buy a second Jet City 2x12 cab, that way I could leave one cab at my band's rehearsal space and move the other one between home and practice for jamming at home. This way at home I could run the amp into the cab switched to stereo 2x16 ohm and for rehearsal and gigs I could run the two cabs 8 ohm mono from each side of my Mustang head. I don't like packing around a 4x12 cab if I don't have to and they don't fit in the trunk of my little '93 Corolla like my 2x12 and head do.

Anyway, I'm back to assuming that it has to do with the wiring of my cab. But does this make sense to anybody as to why this would be happening? Has anybody else had this issue? I'm handy with a soldering iron and will probably end up opening up my Jet City cab and rewiring from the jack plate to the speakers to ensure that it is a straight shot from each jack to the corresponding speaker, but I don't want to tear into my cab if it turns out the issue has to do with the impedance or some other issue... I assume it's not an impedance issue since the 2x8 ohm Jet City cab did the same thing, but I don't know what else would cause this? Anybody have any ideas?


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Wed Mar 02, 2011 8:10 am
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I bought a Mustang V head last week off the floor (thats all they had at GC) and mine runs fine through a 2x12 stereo ready Fender cab I have thats loaded with 90watt Pyle driver speakers. So my amp head is drawing an 8ohm load from each 12in speaker.

Try a different cab other than Jet City could be a wiring issue.


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Wed Mar 02, 2011 11:34 am
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Sounds like you have something connected incorrectly. What you are hearing is a "feedback loop" or an "open ground". This can happen when a mfx out is feeding a speaker out or any number of other issues.

Another thing that can cause it is an open ground between the amp output and the speaker cab. IF THE 1/4 SPEAKER IN PLUG IS NOT GROUNDED you will get this helicopter sound. If you have, and know how to use, a "continutity tester" check all your connections between the amp and the speaker cab. Somewhere you will find an open ground. That place needs to be grounded. SS amps are particularly prone to this. Tube amps just shock the Hexx out of you when you least expect it! LOL

I am 95% sure that it is not the amp but the connections between the amp and the speaker cab. I'll bet if you took the speakers out of the cab and connected them directly (use aligator clips to connect to the speakes) you will find that the feedback goes away.

Just my two cents worth . . . blessings, Bo Baker


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Wed Mar 02, 2011 4:44 pm
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Thanks for the replies. I was thinking it was a grounding issue, but wanted to make sure. I actually went today and bought two new 1/4" jacks and some heavy gauge speaker cable. I took the jack plate out of the cab and unhooked the wires; I was thinking I'd build a new jack plate and just have two completely separate jacks with no switch. I got half way done assembling it before I had to take off to work, so I suppose I'll see later if it fixes the problem.

I've tried 5 different sets of speaker cables, so I know it's not a speaker cable issue and having tested two different JC cabs and getting the same thing tells me that it's in the way Jet City wires their cabs. I don't know if this would cause it or not, but is it possible that Jet City runs both grounds into one going into the switch? I know that Jet City only builds tube amps and they don't have any stereo heads in their product line, just tube amps that have the option of two speaker outputs running in parallel.. With their amps it wouldn't matter if the grounds crossed, but with a bi-amped amplifier like the Mustang it would matter, right? Just a thought, and I don't know if it's completely off, I'm no electrical engineer... I also don't know how to just look at the board on the back of the jack plate and tell if they have it wired that way or not..

Anyway, I guess I will see later on tonight if my new homemade jack plate will do the trick. I really hope so, because I really like the eminence speakers in the Jet City cabs. They're really loud speakers. And this head and cab combo is one sexy setup. I also gotta say that with the jam time I've gotten with the Mustang using headphones and playing around on Fuse, this thing is a beast. I love it. The effects are top notch and with the amp models it has this thing is a tone machine.


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Wed Mar 02, 2011 6:03 pm
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What you want to make sure of is that the ground side of the cables 1/4 plug (the outside sleve) is grounded to the "ground lug" on the 1/4 female socket plug. If not you have an open ground. I know of a person that used a "plastic plate" to attach the two female 1/4 plugs to the back of his cab.

The end result was that there was no common ground between the L and R inputs and he got the symptom you are talking about.

As soon as he used a "metal" plate and drilled holes for the two Female 1/4 plugs the common ground between the two was re-established.

You could test this by jumping a wire between the two jacks and see if that resolves the issue.

Good luck - it's not the amp - it's in the cab.


Bo Baker


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Wed Mar 02, 2011 6:11 pm
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So you're saying that you want the ground on both jacks to be connected? Does that mean if I just ran a little piece of speaker wire from the ground terminal on the left jack to the ground terminal of the right jack on the existing jack plate it may solve the problem??


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Thu Mar 03, 2011 4:42 am
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itshreds wrote:
So you're saying that you want the ground on both jacks to be connected? Does that mean if I just ran a little piece of speaker wire from the ground terminal on the left jack to the ground terminal of the right jack on the existing jack plate it may solve the problem??



Yes that would be a quick check to see if that is the issue. "Ground" is common to all components. Current has to have a complete path from plus (+ positive) to negative ( - negative). If there is a component that is not grounded that "current" has to go somewhere and one of many things that can happen is that it starts to "jam" (for lack of a better term) and you can get your issue - or worse!

What I believe you are hearing is the current going back-and-forth in the speakers and "fluttering" the baffels. Not a good thing to do. The current is trying to find a ground but can not, so it just keeps going back and forth.

The same type of thing can happen when your "ground wire" from your guitar bridge to your common ground in your pickups is broken (lifted). You start to hear a "hum" and/or hiss. When you touch the strings with your fingers/hand the hum/hiss goes away. That is because YOU are now the common ground between the strings-the bridge- and the electronics in your guitar. As soon as you lift your hands the issue re-appears. (A bit off topic but given for further clarification on what can happen when any electrical device is not grounded properly.)

So take a wire from the outside of the casings on the 1/4 phono plugs going into the cab L/R and see if that stops the issue. If it does - then create a common ground between the two any way you want. Make it inside the cab, of course! If this does not fix it - then there is an open ground somewhere else or it is an entirely different issue.

My guess is that this is a grounding issue. Perhaps a call to Fender support will further clarify this for you.

Good luck, Bo


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Thu Mar 03, 2011 10:57 am
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I fixed the problem! I did what I originally said I was going to do and built a new jack plate and wired the speakers/jacks separate of each other with no mono switch capability. I built a plastic jack plate, the jet city one was metal. It seems it was what I had suspected with the bi-amped amplifier needing to not share a common ground for the two sides..


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Thu Mar 03, 2011 11:50 am
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:D Congrats! Always fullfilling to figure something out . . . and learn a thing or two in the process.

Blessings, Bo


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Thu Mar 03, 2011 12:46 pm
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itshreds wrote:
I fixed the problem!
that awesome! So how does it sound???? :)


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Thu Mar 03, 2011 4:42 pm
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It sounds great! So far it's everything I was hoping it would be. I did a lot of studying before buying the two, but apparently not enough to know that they weren't going to work together right out of the box, haha.

The Eminence speakers that are in the cab are supposed to be almost identical to the Eminence Legend guitar speaker. It's a really efficient speaker, and it's also really good at re-creating the tones I hear through my headphones with this amp. It's not completely transparent, but it really wasn't built to be. Very good tone, though. When I turn the speaker emulation off in Fuse and play through the cab it comes pretty close to sounding true to the 2x12C speaker emulation with the headphones on.

I like this setup more than any 4x12 set up I've used in the past, the 2x12 sounds a lot less muddy while still having a good low end and the Mustang V is a killer head. I love the sounds you can get out of this thing.

Tomorrow I get to see how this thing stacks up at rehearsal with the full band. I'm pretty anxious to see how it'll do there. I'm really anxious to see how It's going to sound when I buy a second 2x12 cab some time down the road, then I'll get to see how this beast sounds pushing the full 150 watts.

I should post a picture of this setup later, it looks beautiful. They seriously look like they were built for each other. The JC cab is an "oversized" 2x12 cab, it stands about 20" tall I think and about 28" wide. The head is almost a perfect fit on top of the cab, there's not even an inch to spare on all sides. It makes it look monstrous for such a little stack and they're both classy looking gear. Kind of funny, I know.. It's more about the tone, but I also love a good looking setup.


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Sat Mar 05, 2011 4:03 pm
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As an update to my last post, I finally got to see how my little stack stacks up in rehearsal. The gear that my band uses include a 500 watt practice PA, the other guitarist's 120 watt half stack, the bassist's 220 watt Ampeg combo, a big drummer with a heavy hit, and now my Mustang V/Jet City 2x12 stack. Since I haven't bought my second cab yet my amp is pushing a 16 ohm load, so at best a little more than half the power of it's full 150 watts. That being said, this little setup didn't have a problem at all keeping up. In fact, the other guitarist had to keep turning up to be heard and I never turned the master volume above 5. I've owned Fender amps before and I knew that Fender doesn't fudge at all on their power ratings, their amps deliver. The Mustang V is no exception. I'm going to have to go back and redo a lot of my presets I had made, because the treble was a little harsher at high volumes, but that's a pretty simple fix. Besides that the tones were amazing and I loved not having to unpack my delay, reverb, and dirt boxes. The effects on the amp sound great and I've got more effects options now than I had with the few pedals I was using. I really love this setup. My one complaint about the head: I have no idea why Fender built a solid state head with a headphone jack that mutes the speaker outputs. It would be so much handier when it came time to play a show if I could just run a cable from the speaker emulated headphone out to the pa and still had the speaker volume for on stage monitoring. If you want to jam at home with no speaker volume you could just unplug the speakers on a solid state head and it wouldn't hurt anything, so what's the point of making them mute when you plug the headphones in? My one complaint with the cab: I had to modify a brand spanking new cab to be a truly stereo cab when they claim it's mono/stereo switchable... And Jet City's ridiculous "333" logo, what's up with that? Other than that it's a great cab and this head and cab make a great combination.

Anyway, here's that picture I promised, too:

Image


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Fri Apr 01, 2011 3:25 am
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"I haven't bought my second cab yet my amp is pushing a 16 ohm load, so at best a little more than half the power of it's full 150 watts"

You lost me, Is your 2x12 set up for stereo? Left and Right channel. Are you using the right and left speaker out on your head? This way you are pushing 75 watts per speaker! ie 150 watts.


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Fri Apr 01, 2011 3:30 pm
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I am using a stereo cab, I am using both outputs on my head, but the head is rated at 150 watts (75 watts per side) at an 8 ohm load. I'm using a 16 ohm load on each side, not an 8 ohm load on each side. That means that the speakers are giving more resistance than what the amp can push it's full 150 watts of power through... Twice as much resistance. This means that I'm only able to push approximately 37.5 watts of power through each side of the head, so 75 watts total. Half the power the amp can push at an 8 ohm load.


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Post subject: Re: Mustang V not working with my 2x12 cab...
Posted: Fri Apr 01, 2011 3:36 pm
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If I buy another cab, two 16 ohm loads make an 8 ohm load... So two cabinets that each have two 16 ohm speakers in them makes an 8 ohm load for each side of my head, so I could be pushing the full 150 watts from my head.


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