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Post by lathspell on Oct 6, 2020 14:05:28 GMT -7
Howdy, all! Brand new to the forums and have had my first Dr. Z amp for just over a month now. I bought the MAZ 18 Studio combo with the standard Vintage 30 in it. However, I also have a Marshall 2x12 slanted cab that I like running all my amps through. The MAZ sounded great by itself, but sounded like I threw a blanket over it when plugged into my cab. Way too bassy, even if i rolled the bass pot all the way off. I decided I needed to swap the V-Type speakers for something different to bring out more clarity and remove all the bass i was getting.
This leads to my technical question. I bought a pair of used 8 Ohm Greenbacks to put in my cab. I originally wired them in parallel because that was how the original speakers were wired. If my math is right, that should mean I need to plug into the 4 Ohm output for the cab. When I did this, it sounded VERY fizzy and harsh. Not good at all. Made me upset because now I had to look for a different speaker combination and play the waiting game, then resell these Greenbacks.
Before I did that, on a whim, I Just randomly decided to wire them in series and plug the cab into the 16 ohm output. HOLY CRAP! That is the tone I have been looking for! Punchy and articulate with plenty of room to turn up the bass on my amp, if I need to.
Is anyone technical enough to explain to me why there was such a difference between the 4ohm output with speakers in parallel vs the 16 ohm output with speakers in series?
Decided to post in the Maz 18 thread because that is the combo amp, but feel free to move the thread if it should go elsewhere.
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Post by jhen86 (jordan) on Oct 7, 2020 5:50:07 GMT -7
Your ears arent tricking you. Series and parallel are different. I’ve started to liken it to the difference between a fixed bias sound vs cathode biased. Parallel with its lower impedance and both speakers hitting together tends to have a little more power behind it, more punchy, and firmer (more immediate) up top. Things kinda keep together more. Kinda like fixed bias.
Series, has a higher impedance, signal hits one speaker then the other, and tends to have a more smeared texture to it. A little grittier and looser. Almost like cathode bias. Note: speakers have nothing to do with bias, just trying to make an example.
If 16 ohms in series does it for you, then rock on!
Now...I’m not sure what exactly you heard and if it was truly correct at 4 ohms. One great precaution is to test your speaker cab polarity and impedance before plugging it up. Your speakers could have been out of phase in parallel if it seemed awfully bright and weak.
For polarity/phase, you can use a 9v battery. Then make sure the impedance is correct with a multimeter. A 16 ohm cab should show about 14ohms of resistance on a multimeter. 4 ohm would read about 3.5 ohms. Lots of YouTube videos showing how to do those ^^^
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Post by jhen86 (jordan) on Oct 7, 2020 5:54:54 GMT -7
And welcome by the way. Lots of nice and knowledgeable folks here.
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Post by lathspell on Oct 7, 2020 20:39:05 GMT -7
Appreciate the input and welcome.
I was thinking that, somehow, the 4ohm in parallel was causing the speakers to clip more. I wouldn't call it a weaker sound, just fizzy. I'm fairly certain I wired them correctly, because it was the exact same wiring as the Vtype's that were in there originally. However, I wouldn't bet my life on it.
I played for a while, today, and am definitely loving the setup
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Post by John on Oct 8, 2020 5:29:33 GMT -7
From the information given...and not being able to hear what you heard, it would lead a person to believe you wired the greenbacks out of phase. Or at least that would be my best guess.
Greenbacks have less bass than a lot of other speakers, so that should take care of your bass issue. (They have smaller magnets, and can't kick out the bass like a large magnet speaker)
And I have little/none experience with series wired speakers, but I can't imagine there would be enough of a difference for a person to go from 'fizzy and harsh'....to 'HOLY CRAP' with just a change from parallel to series. Yes, there will be a difference us guitar geeks can tell, but I wouldn't imagine it would THAT much, especially in the same cabinet. (correct me guys if I'm wrong.)
That's what leads me to believe the greenbacks were wired out of phase.
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Post by Don A on Oct 9, 2020 11:13:05 GMT -7
I agree with the statements that the speakers might've been out of phase.
The difference in sound between the speakers being wired in series and parallel is subtle. Many people wouldn't even notice the difference. Wired out of phase makes a huge difference.
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Post by jhen86 (jordan) on Oct 10, 2020 7:16:18 GMT -7
Greenbacks are known to break up more than most. The power/punch of Being hit in parallel could have caused a tad more rattiness, that series would have smoothed out. That may be what you heard. Hard to say.
If you like it, leave it. Or if you’re curious, try parallel again and confirm speakers are moving out and in together with the 9v battery. Easiest way is to wire cab up, plug one end of the speaker cable into the cab and touch the 9v to the other end of the speaker cable leads. That way you are testing the system all together. If one pushes forward while the other pushes back, they are out of phase. Flip the +/- leads on one speaker and try again.
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Post by lathspell on Oct 10, 2020 17:32:20 GMT -7
I figure it sounds great now, so I will go ahead and leave it. Loving my MAZ 18 through this cab. This is the tone I've been looking for, with the ability to clean up so well with my guitars' volume knob.
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Post by lathspell on Oct 10, 2020 17:32:32 GMT -7
Appreciate the feedback!
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