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Theoretically speaking is the there any advantage to using a 16 ohm load as opposed to 8 ohm or 4 ohm load. The West Lab O.T. gives the option for either 4,8, or 16 ohm output, anyone?

This topic has been the center of flame wars for as long as I remember the internet having forums (actually, I remember it in old school newsgroups as well).

There are people on both sides of the fence. There's a group that feel one particular ohm load sounds better than another. You'll hear people that claim an amp at 16 ohms sounds better than the same amp at 4, etc, etc. I've heard some rationalize it down to plain ole volume. Where an amp feeding a 16 ohm load isn't going to be as loud as a 4 ohm load....and with respect to that, you'll have to turn up the amp with a 16ohm load to get the same volume as the 4 ohm load. The volume difference that you have to make up means that the amp works a little harder, making 'better tone'.

Then there are people that claim it's all hogwash and an amp feeding a particular resistance is no different, sound wise, to the same amp, properly feeding a different resistance.

I tend to fall on the side of the hogwashers. I think the volume difference between 16ohms and 4 ohms is *so* small that it's rediculous to suggest someone can hear the difference. Maybe some guys can...I certainly can't.

I find the different ohm options on the back of an amp, a convenience. Sorta like a universal adapter so you can plug into other cabs that are different loads.

When I start my lightning build, You can bet the doublewide that I'm either going to drill a 4th hole for a 16 ohm tap, or I'm going to put a switch on the back to switch the output from 4 to 8 to 16 ohms.

Why build such a cool amp, when you can't unplug it from your cab, lug it over to your buddies place and plug into his cab because his cab is a 16 ohmer?

-F

I have three jacks for 4, 8 and 16 ohm speaker options on mine.

On Matchless amps, and the West Labs transformers however, you should know that there is a designed 100% impedence mismatch: the "8 ohm" tap is really the 4 ohm tap, the "16 ohm" tap really 8. For clean power, connect an 8 ohm speaker load to the "4 ohm" tap. For the "Matchless sound" connect it to the "8 ohm" tap. It does make a difference, mostly in the smoothness of breakup. Not sure why Sampson did this but it does work.

http://home.earthlink.net/~jeirvine/lightning.html

-John I

John I

Just curious. Do you mean that Matchless labelled their taps that way? I ran some ac through the Westlabs trannies and, although I don't have the numbers in front of me, I recall that the Pri Z for each tap was appropriate for each load. i.e.; approx 3600+ for the 8 ohm load, 3800 for the 16 & 3700+ for the 4. So any tap was apparently designed with an approximate 4K Pri Z. Obviously you could double the load for an 8K Pri Z.

Been inside of several actual lightnings but didn't have time to eyeball which tap was marked what. Makes sense that they may have done this though. Probably a 'happy accident' they discovered from engaging the half power switch on their DC30.

Philip Morrison

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Philip

If the OT has more than one tap on the secondary and you have room on your chassis, it'll only cost a couple extra bucks to add the jacks, or an impedance selector with a single jack. I think it's most flexible on combo amps to wire the speaker(s) to a plug with the output jack(s) on the chassis, as opposed to just hardwiring the OT to the spkrs. That way, you can always unplug the combo's speakers and run the amp through another cabinet, OR run another amp's output into the combo's speakers. CraigB

The lower impedance taps on a transformer only use part of the windings (they are, after all taps). So, in order to use the full transformer, and getting the advantage of more iron, you run it at the highest impedance you can.

P.

I drilled the extra hole to add the 16 Ohm tap to mine. Of course, I didn't have much choice since I ordered a 16 Ohm speaker for it ;)

Here are some pics of the finished build:

http://www.18watt.com/modules.php?set_a ... _photo.php

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--s2
www.s2amps.com
www.category5amps.com

S2:

I really like the black front/back plate better! Are you liking the Lightning better now? I know at first you were a bit disappointed with it and a strat.

I think I'm liking it better now that the speaker is breaking in and I'm learning how to use the amp better. With those Vox-like tone controls, I'm having to relearn... [embarrased]

I'm still thinking about a cut control in the future to help tame the highs, but I probably won't open this amp up again for quite some time.

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--s2
www.s2amps.com
www.category5amps.com