A Stupid Question.

ehb

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The amp is a Genz-Benz El Dorado 60 Tribal Series (whew!).

From your manual

1637260148021.png
 

Dolebludger

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Thanks all! I’ve had that amp for over 10 years and it hasn’t been used for 7 years. So I have no idea where the owners manual is.
 

ehb

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Yes, the outputs are parallel...

Series parallel happens inside the cab depending on desired ZT...
 

Southwest

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Turns out it wasn't such a stupid question after all. I've certainly learned a lot from the responses. And redneck logic is brilliant!
 

ehb

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Folks blow up more car amps probably than anything... They think two speakers sound good so four speakers will sound more better.... They then are all happy about how four sounds so they add two more......Dayum... Let's add two more and so on.... Impedance ZT keeps dropping so the current keeps increasing until it hit s the TMS point. (Tuned for Maximum Smoke).... Some amps have impedance matching circuitry to keep amp configured to adjust to different ZTs. Some have no circuitry for such but will say 'Don't go below XΩ on output.... That's why they have different output Wattage for different ZTs listed....

i.e. 200W at 4Ω but ballpark 120w at 8Ω. (just picking Wattage numbers)
 

ehb

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And redneck logic is brilliant!

Used redneck logic quite a bit teaching reactive components (capacitors and inductors (coils).... I'd talk about shock absorbers, truck springs, and trampoline fabric, for a while....cars going up slow slopes (rise/run) hills (slow Δ). vs. a quick Δ hill (incline changes real quick, or decline same) and how those devices 'react' to change....

When they could understand how the car's shocks/springs react, then that magic 63.2% rate of change per unit time made sense.... Then they could understand the math to calculate easily instead of memorizing something for the sake of memorizing something.... They understood what was happening...

I'm a redneck, sooooo...... ;)
 

Dolebludger

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I use two separate 1X12 cabs so speakers may be put a distance apart to better fill the area with sound. I also put them on stands about 2’ off the ground and tilted upward. I find that it gets the sound out where I want it at lower volumes.
 

ARandall

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It would be interesting to know if there are any amps that actually have options for multiple cab series connection.
I mean you cannot have a series only connection with the option of only connecting 1 cab for example (open circuit obviously).

I know certain speaker cabs have the same options (where you have 2 jacks and the possibility of series or parallel for the speakers). But its a switching scenario.....not where if you plug into the second jack that you get both in series automatically.
 

strayedstrater

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It would be interesting to know if there are any amps that actually have options for multiple cab series connection.
I mean you cannot have a series only connection with the option of only connecting 1 cab for example (open circuit obviously).

I know certain speaker cabs have the same options (where you have 2 jacks and the possibility of series or parallel for the speakers). But its a switching scenario.....not where if you plug into the second jack that you get both in series automatically.

MusicMan HD amps had series outputs. (HD65, HD130, HD75, HD150 -- I'm not sure about the RD/RP series.)

There was a "main" jack and a switching "extension" jack that put the jacks in series (if you were only using one jack you had to use the "main" jack -- if you only plugged into the "extension" jack by itself you'd have an open circuit.) They had no parallel output jack.

Most were labeled as series jacks. But some weren't and you wouldn't know unless you read the manual.

Fender's red-knob "The Twin" had a "main" jack with both a parallel ext jack and a series ext jack. (Again the series jack was a switching jack that couldn't be used all by itself.) The blackface channel-switching "Twin Amp" that replaced "The Twin" also had parallel and series ext jacks. (Those were "families" of amps available in different wattages with different speaker compliments -- they may have all had series jacks but I don't recall.)

("Twin Reverb", "The Twin" and "Twin Amp" may be the most confusing model names ever.)
--------------------------
Amps with series jacks are very uncommon, and usually if they're unlabeled it's safe to assume they're parallel.

But some of the MusicMan's with series jacks were unlabeled. So if you're not sure it's never a stupid idea to ask.
 
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mgenet

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Damn, sounds like good question Dole; you got a few answers there...
 

Bobby Mahogany

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Not stupid. Few have a clue as far as impedance....

Redneck logic:

If you add another pipe in parallel and said pipe is the same as primary, then twice as much water can be delivered so the OPPOSITION TO WATER FLOW HAD TO HAVE DECREASED BY SAME FACTOR.

If you fill up a 55 gal drum with water and let it sit. Flow is zero and opposition to flow is infinite.
With a sharpened stretch of rebar, jab a hole. flow went from zero to a flow rate determined by hole dimensions and opposition to flow decreased from infinite (no hole) to opposition dictated by hole dimensions.
Jab another hole of same size, TWICE as much water is coming out, so opposition to the water leaking out was just decreased by the same factor, HALF the previous opposition.

Water is the current. Pressure is the same across all parallel paths. Opposition is the relationship between rate of flow and pressure.


Plug one 8Ω cab in an amp and you will have 8Ω total opposition to current (load).
Plug in another 8Ω cab and you create another identical path for current. So, since pressure is the same across all parallel outputs, then the load current must DOUBLE. If current doubled, pressure (voltage) stayed the same, then total opposition had to have been affected by the same factor but inverse.... Sooo, total output impedance is 4Ω...

The source (amp) sees 4Ω. It neither knows nor cares what that 4Ω consists of.


Every outlet in you house is in parallel. Plug one lamp in. Voltage stayed the same, current INCREASED soooooo the total impedance (opposition to current flow) had to have DECREASED....

Plug another identical lamp/bulb in and Voltage is STILL 120v....BUT another identical path for current has been created so current doubled. Sooooo, total impedance had to have been halved...



Lots of folks have blown up amps from NOT understanding load (current). The lower the impedance, the more current the source must supply.... If an amp is rated at 4Ω, if you go below 4Ω, you are forcing the source ( amp ) to supply more current than it was designed to handle......and sooner or later something is gonna give....


Remember: Everything can be a smoke machine if you operate it wrong enough...

edro.

Thanks for playing with our brains.
What was the question again?

:dunno:




:laugh2:
 

Dolebludger

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No, I’m now convinced that my amp head has parallel speaker output jacks, and when I plug my two 8 OHM speaker cabs in to it, I will set it on 4 OHMS. I guess this thread has proven that people other than me don’t understand impedance. I had only stored this amp head since I got my Soul Tramp Wraith head in ‘14. I have changed much in my gear since then. I decided that, before I tried to sell the Gens-Benz, I should play it a bit. Now I’ll fire it up and see how it sounds with new speakers and new FX, and see what its got.
 

ehb

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ehb is the bestest redneck on MLP if not in the US of A.

Thanks, bud!

I ain't braggin' but everybody ain't be graduated elementary school before they get they drivin' license like I did....
 

Rocco Crocco

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Here's a really stupid question... is it still necessary to match the impedance at lower volume?
 
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