Lonestar Special output impedance question

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ja22y

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Just got my first Boogie last week and I'm still trying to figure this thing out.
In the manual, it mentions that the Normal output is 4 ohm and the optional out is 8 ohm. Don't know why they just don't label the impedance right on the panel.
Does anyone know why at 30w, the output impedance is 8ohm and at 15w or 5w it's 4ohm ?
It's strange to me that you'll always have a speaker mismatch if you have don't have the same power setting on both channels. Did I mis-understood the manual ?
 
Any LS owner out there ?
I looked at it some more and it still doesn't make sense.
Main out is 4 ohm and speaker is 8. In any other amp that I have, the 1st thing you do is match the impedance else you''ll lose some volume and high freq. May be this is why some LSS owners complain that there is not enough clean head room.
I need to call Mesa on Monday, but until then any insight is appreciated, this thing is bugging me.
:roll: :?:
 
It was the only way they could get the 4/2/1 tube thing to work without switching to a different output transformer at the same time. If you pull one pair from a Fender Twin the output impedance goes down from 8 ohms to 4. Same thing happens on a Mesa amp, laws of physics will prevail. From what I understand having read the interview with Randall Smith, the 1 tube mode (Single Ended) still has two tubes running, just the audio from one of them is shunted to null. It is a clever trick but compromises had to be made to pull it off, simple as that. Hope this helps. :D
 
thanks, it does help. The shuning one tube for single tube explains it. Is that in the article on the mesa web site ?
Since I'm new to Mesa, does it mean all amps that have half power have impedance mismatch ?
BTW When I plug into the 8 ohm, and running 30w mode, finally I have clean enough headroom and seems like a blanket have been lifted from the amp. It has more punch and 'breath' and note is not compressed. Not sure why this is 'option' and not normal.
 
I think the reason Mesa doesn't label the output impedence is because it changes at different power levels--that is when running a 30 W, the outputs are 8 ohms, 4 ohms, and 4 ohms, but when switching to 15 W, the outputs are 16, 8, and 8 ohms.

So the far left jack is matched to the internal speaker at 30 W and it is mismatched at 15 W & 5 W

The center and rt output jacks are matched to the internal speaker at 15W &5 W and mismatched at 30W

The greatest mismatch the amp will see is 2:1, which is OK according to Mesa

As pointed out above, the 5W mode operates like the 15W mode

I think it sounds best when the speaker is matched to the output.
 
thought I have this understood until I talked to Mesa today.
According to Chris, the output will always be 8 for the option plug and 4 for the two mains. Switching the power selection doesn't change the impedance. Mesa labeled Main since they think that the amp sounds best at this mismatched. :roll: :!: :!: :!:
Now I'm totally confused.
 
the output impedance remains unchanged from a static point of view. Plug the values into ohm's law.
 
I may be missing something, but if the impedence requirement doesn't change, then at the 15/5W setting the amp would have a mismatch using the main outs. But according to the LSS manual, the impedance of the main matches the 8 ohm speaker at 15/5 W and the impedance of the optional output matches the 8 ohm speaker at 30W. I'm not seeing how the impedance won't change with four tubes instead of two [i.e., if the mains expect to see 8 ohms at 15/5W, and that's a match--8 ohms at the mains, then 30W adds two more tubes in parallel (8 x 8 )/(8 + 8 )= 4 ohms at the mains]

Here's the paragraph from the manual:

"The Lone Star Special provides one OPTIONAL / 35 WATTS (8 ohm) and two MAIN /30-15-5 (4 ohm) speaker outputs and this enables you to use many different combinations of speaker setups. The MAIN jack is preferred for most vintage inspired sounds where a smoother, warmer character will be noted in all three power selections and an impedance correct match will be achieved for the 15 and 5 watt selections and a slight mismatch will occur in the 30 watt setting where maximum power will be about 30 watts. Using the OPTIONAL jack will produce a correct match for the 30 watt selection boosting overall power to about 35 watts and producing a slight mismatch in the 15 and 5 watt settings (which is fine and may be preferable) giving all three selections a little more punch in the midrange frequencies."
 
RocksOff said:
the output impedance remains unchanged from a static point of view. Plug the values into ohm's law.

Huh? Ohm's law has nothing to do with it.

Output impedance definitely changes as you take tubes out of the circuit. Whether it matters to you (clearly it never has with Mesa) is another issue.
 
Called Mesa again and got the same answer (from a different person) that the ouputs are static. I insisted for the Customer Service rep to get a definite answer from a tech since this statement is contradicted with the manual and the knowledgeable people on this board, and here is the scoop:

The speaker is 8 ohm.
Main out: 30w - 4 ohm
15w - 8 ohm
5w - 8 ohm

Option out: 30w (actually 35w) - 8 ohm
(not sure what it is at 15/5w but it's mismatched and not recommended). I'd guess based on the above that it's 16 ohm. which is not a good setting since the amp will be driven hard with the load impedance lower than the output.

So there you have it. I can sleep easy now. :D
Now I know that I get the best tone out of this amp becasue the impedance matched.
Why can't they just put this bit of info in the manual. :idea:
 
The OT is set up for 4xEL84 to 4 ohms. So in 30W mode the amp wants to see 4 ohms, in 15W and 5W it wants to see 8 ohms.

The question is, what does the 'optional' jack connect to? According to the manual, it's an 8 ohm tap. At 15/5, it would want to see 16 ohms.
 
ok.... i have a LSS 2x12 combo and i replaced the Black Shadows with Vintage 30's. I kept them in the same ohm rating which is 16ohm a speaker. The amp load is 8ohm and I have a 2x12 Recto cab with 2 Celestion Greenbacks which is a 4ohm cab now. So how would I run everything together??? Im guessing I run the combo speakers to the optional jack and the cab to one of the other jacks. Would this be a mismatch for the recto cab? Do i have to change the wiring in the recto cab from 4ohm to 16ohm? All of this is REALLY confusing!!!!! :?
 
At 15W/5W, optional = 16 ohms and mains = 8 ohms

Since Mesa says a 100% mismatch either way is OK, you can plug into any output at any setting and be safe, although the tone will change a bit.
 
Well, I hooked up my recto cab lastnite and I noticed that the highend was comprimised a little. I guess the 4ohm cab is putting the overall load to low. Im gonna try wiring the Greenbacks in the cab to 16ohm and see how that sounds.
 
ricardo loma vista said:
Since Mesa says a 100% mismatch either way is OK, you can plug into any output at any setting and be safe, although the tone will change a bit.

I don't think that is true. Mismatch is safe when the output is going to a load with higher impedance and not when the load has lower impedance, depedning on how much lower. If the output is at 8 ohm and the cab is 4 ohm, it will draw twice the current then if the cab is 8 ohm. Meaning the tube will be driven twice as hard.
 
ja22y said:
I don't think that is true. Mismatch is safe when the output is going to a load with higher impedance and not when the load has lower impedance, depedning on how much lower. If the output is at 8 ohm and the cab is 4 ohm, it will draw twice the current then if the cab is 8 ohm. Meaning the tube will be driven twice as hard.

This is potentially disasterous advice. NEVER place a higher (numerically) load on a tube amp.

Lower is safe...the load asks for more current, the tube simply refuses to provide it. And actually, the same is true for higher loads, EXCEPT higher loads create extreme flyback voltages.

Tube amps don't work like solid-state devices.
 
OK... let me see if my thoughts are correct then. So, according to the info on this thread I should be OK running the combo speakers into the optionl jack which is 8ohm and run my recto cab which is 4ohm to one of the other jacks since they are 4ohm. Am I getting it right? Or are the other regular jacks 16ohm?
 

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