Two 18 watters as loud as one 36 watter?

[E-rex]

My results with two 18watters are pretty much as predicted. Both 18W LiteIIb's. Both going into a 8 ohm partial-open back 1x12 cab with a silver bell. About 3-4 dB louder with both than with either alone. Same result either clean or dirty, though with both cranked to max, it seemed WAY louder than with just one. It was very exciting. But, according to the sound pressure meter it was only 3-4 dB louder, which is the theoretical difference between a 18w and a 36w.

Test was performed in our 4500 cubic foot band practice room using a rat shack meter set back about 12 feet from the cabinets. When running both amps, I spit the signal with a Lehle P-Split. (very nice signal splitter---very happy with it's performance)

I don't have a 36 watter to compare the two 18 watters to. Hmmmm, maybe I better build one? Hmmm, then I could run all three amps!!!!! Haaa!!

The advantage I was going for with two 18's vs one 36 is that I need a backup amp anyway. I would never go to a gig with only one amp. Plus you can position the 2nd amp where ever you like...adding more flexibility.

[breakfastbuddy]

it takes more of the amp to amplify lower sound waves as bas , if the amp is ampliyfing higer sound waves within the human ear it will sound higer too .
thats why a bas amp has to have a lot more power to keep up with the sound level in the band . that means is you have bigger coupling caps and more bas sound it will not sound as high as the same amp with smaller coupling caps .

[sreiter]

me and forum member blewsbreaker jammed a week ago

we both have original 18w'er

we were on around 7 or 8 volume

it was loud, but i dont think they were "gig" loud

i think a 36w would be louder

[bitsandvolts]

I dunno, this seems like a bit of an academic question...and almost unnecessary.

If I were to run two 18 watters each into their own 1x12 cab would it be as loud as one 36 watter into a 2x12?

If I get the OP correctly, we're talking about 2 18watts into a single speaker each vs 36 watts into a 2x12.

I'm going to buck the trend and assuming all other things are equal....the 18 watts (side by side) into their own speakers, might either be the same or win out slightly.

a 36 watt amp, driving 2 speakers, is going to in-theory, send about half it's outlput to each speaker. This, is really no different than an 18watt sending all it's output to one speaker. The only difference is that you're not sharing critical components in one amp.

I'd be curious to hear if those that have done this test, did so with comparable factors. meaning...same guitar, speakers, same approximate location of speakers, same exact components inside, was each amp brought to the same volume/compression point? This last point, I think is the most imporant one. A 36 watter is going to reach a certain point of power tube compression a little later than its comparable 18watt brother. So if you are able to bring the 36watter to some *measurable* point of compression and then bring each 18watter to the same point (irrespective of their volume knob positions)...you should, in theory...get 2 18watt amps together, be roughly the same, volume wise, as one 36er.

Then, the intangibles come into play. Does the 18watt circuit with it's own set of caps, resistors, OT, etc bring more or less efficiency than the 36 watter having to share the same types of components among 2 more power tubes???


But if it's just one guy taking 2 non-similar 18watt amps (without some significant control over components) and a 36 watter...and trying to run a comparison....I think it's hard to definitively state one way or the other.

[pylet2000]

I'd contend that both situations would probably be just as loud, but the two different rigs would probably have notably different character and different logistical advantages.

With two 18 watters, you'll be splitting the guitars signal across two tube grids, which is going to change the character of the preamp noticeably. The PI in the 18 watters is going to drive the power section differently than the 36 watters, given one PI for two tubes as opposed to one PI for four tubes. The OT (which we've pretty well covered is the heart and soul of a good tube amp) is going to be very different and have a different feel set up for 4 tubes as opposed to two tubes.

Logistically, two 18 watt amps gives you a lot of flexability on a gig. If you end up being far too loud, you can take one of the amps out of the equation. With the 36 watter, you've got one less amp to bring in, always a good thing, but less flexability.

So it's probably not something that you can compare in simple mathematical logic (distributive property?). I think there are far too many little variables to make it a simple deal.

Build them all then, there's the solution!

[bitsandvolts]

With two 18 watters, you'll be splitting the guitars signal across two tube grids, which is going to change the character of the preamp noticeably.

Unless you're using a buffered splitter, which I would recommend in such a scenario.

[loyjdockery]

You could just also use a variable voltage regulator on a 36 watter if you're concerned about it being too loud. I've heard only good stuff about it!

I'm really excited to slap one together on one my amps and give it a whirl. There's a demo by Gabi in one of the threads around here that has convinced me of late.

[E-rex]

With two 18 watters, you'll be splitting the guitars signal across two tube grids, which is going to change the character of the preamp noticeably.

Unless you're using a buffered splitter, which I would recommend in such a scenario.

Yep. As I said, I used a lehle p-split.

Each 18W lite IIb had it's own cabinet. Each cab had a silver bell in it. Used the same guitar. In the same room. Measured from the same distance...about 12 feet. My background is industrial engineering and I have a fair amount of experimental design experience. The only thing missing was a 36W.

Anyway, not rocket science or anything...was originally just asking if anyone had compared the volume of two 18's to one 36.

I think my next amp will be more like 1.8 watts.

peace out

[zaphod_phil]

me and forum member blewsbreaker jammed a week ago

we both have original 18w'er

That must have sounded sweet!

Envy........