From rafael2pop@yahoo.com.ar Fri Sep 09 07:57:48 2011
Subject:Re: Leslie woofers 16-ohm

Goff and Everyone,

Just a reminder, as rule of thumb "it shouldn't be used a loudspeaker of less impedance than rated on the spec label for the amp".

No problem is the speaker is designed for greater impedance

Conversely NEVER use less ohms on the speaker side than required by the amp ohms.

Notice: if the amp tells " 8 ohm" it even will tolerate 16 ohm charge but if so that loudspeaker will drain extra RMS power from the amp.

OTOH , should same amp (8 ohm SPK output ) wired to a 4 ohm car-audio speaker, loudspeakers will be at risk for sure.

ANOTHER SCENARIO AMP: 16 ohm tube amps:

Having a 16 ohm output amp, and anybody think to put there a 8 ohm loudspeaker, it will be the same risk as mentioned about a 4 ohm car audio wired to a 8 ohm rack style power amp.

On a Leslie amp no problem if it's wired with a 16 or 32 ohm loudspeaker, but NOT lesser impedances, except this option:

A solution " ala McGyver " would be to use to use a 8 ohm loudspeaker BUT with extra resistors , let's say of 20/30W (in serie at the output ) so getting 16 ohm impedance to match the intended output amp (Leslie amp with 16 ohm)

Obviously , the resistors will drain part of the charge and energy will be got as dissipated heat instead of speaker power, but still it can be used without risk.

For the purpose a digital multimeter DMM or analog Ohmmeter will be needed for safer measurement of 16 Ohm on the speaker side (combined with resistors)

As alwayws what count is the rated power of the amp, that in case of Leslie amps are not so big ( < dissipated power of two 6550 tubes) this is under 65Watt RMS ).

That is quite far of the average loudspeaker by today standards for on stage use.

So can be understand that extra power for Leslies can be obtained from hybrid approach of tube pre or tube amp (as AMA from SpeakEasy) mixed with a solidstate amp of 150W RMS and above, to get enough sound to make a "guerrilla" with guitar amps on stage

What would be interesting to know the opinion from the experimenters/ connoiseurs (and/or compulsive testers) how a hybrid amp sounds on stage regarging it has both power tubes (6550, EL34 , 6L6, 6L6GC, etc.) AND solid state transistor power

In other words how an hybrid amp stacks against the "old good 147s or 122s " those vintage gems , barely holding a pair of 6550 power tubes.

Best,

Raff

Posted by: "Goff Macaraeg" goffmac747@aol.com goff747
Thu Sep 8, 2011 10:29 pm (PDT)

I know we've discussed this before. Wondered if there have been any updates in aftermarket 100 watt woofers, video/sound clips for regular Leslie use?

What 15 inch 16-ohm gets the correct "wooh-wooh" ramp tone?

Goff