Jest recently bought a 1976 Bassman 100. Posts on the net say that this sounds like a twin or Showman without the tremelo or reverb. Well my Deluxe Reverb is louder. The Bassman sounds ok, just not very loud. Any ideas of where to look first
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Bassman 100 - Should it be louder?
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Hi, agree with Albert's calculations and add:
whether they are RMS, Peak to Peak, average, or whatever, they were measured approximately the same way, and they clearly show that your Bassman has *twice* the electrical power of your Deluxe Reverb, *so*, we have a speaker problem here.
I guess your Deluxe has an original "Fender" speaker, which would be a Jensen in an old one or an Eminence in a newer one. Good, average, standard speakers, adequate to fullfill what's asked from them.
Obviously that is not happening with your Bassman.
What are you using there?
Although twice the Deluxe power is nothing to write home about (to put it mildly), it should still be apreciably louder, not softer.
The good thing is that your Bassman is alive and reasonably well , although it should put out *much more* than the Deluxe, not only twice as much.
We now know that very probably it needs new tubes, *and a new/better speaker*Last edited by J M Fahey; 12-27-2009, 10:54 PM.Juan Manuel Fahey
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Bassman 100
Guys
Thanks for the input. Tubes have been tested and all test good. I used a standard digital VOM to measure the output. The speakers being used in both are Celestian and actually my mistake. On the Deluxe, I am using a 16 ohm speaker
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True RMS meter
Thanks for the info.
It is a nice meter.
It is not a true RMS meter.
Munufacturers quote:
"Full Size Manual Ranging Multimeters (30XR, 33XR)
The XR series of multimeters is designed for electronic, electrical, plant maintenance and HVAC use. Two XR meters are average sensing: 30XR and 33XR."
When dealing with ampifier power equations, you must use true RMS.
So, multiply what your meter reads x 0.707
For more info:Audio power - Wikipedia, the free encyclopedia
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Hi. sorry for having to repeat it, but I must set clear two things=
1)RMS voltage is 1.1 times Average voltage, *for a sine wave*
2) A "common" multimeter, be it analog (needle) or digital, measures *average* voltage, *but* the scale is already corrected, and written in RMS values, at the factory, so you don't need to multiply by 1.1 what you read, it's already done.
Example:
sine wave 10V peak
meter reads 6.37 Volts.
The scale *should* indicate that, but those ckever guys at the factory print a corrected scale (or move a little gain trimmer or reference voltage) multiplying that by 1.1 and:
meter shows 7.07 Volts.
All this holds true for sine waves-
Bottom line is: you don't need an expensive RMS voltmeter to make accurate audio voltage measurements, if you stick to sinewaves (and work within its bandwidth)
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Going back to the Bassman:
if it shows 21Volts into 4 ohms and the deluxe shows 20 Volts into 16 ohms, we are talking an approximate 4:1 power difference, yet it has less volume than the little one:
"whenever you have discarded everything else, what remains must be the truth, however improbable it may look"
In this case, although the measuring method does not (yet) give us a RMS power, both values are comparable, being the same method, the same operator, presumably short time between one and the other.
If we measure 4:1 power in favor of the bassman , yet it sounds less, the only variable left is the speaker; there's no other option.
Forgot link: http://www.sfu.ca/sonic-studio/handb...an_Square.htmlJuan Manuel Fahey
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Bassman 100
First off I want to thank all of you guys that have added your thoughts and experiances here. If nothing else, I have bennifitted from all of you. How does one determine the efficiency of a speaker (s). There is nothing in the specs that say anything.
My original statement about the overall loudness of this amp comes in part to what I remember a friends twin reverb sounds like. Both 100 watt tube amps by Fender, should sound close.......right? I thought so. Anyway, I am bringing my baseman over to my friends house for an A/B comparison with the same speaker cab and same guitar. This ought to prove me right or wrong
Again my thanks to you all and I will report back my findings
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Speaker efficiency is measured in decibels per watt (dB/W).
celestion.com has this spec for all current speakers.
If yours is an obsolete one, assume 97dB/W for smaller 35oz magnet types, 100dB/W for larger 50oz magnet types.
The way this translates into the sound pressure level that we hear, is that a 50 watt amp into a 100dB/W speaker is as loud as a 100 watt amp into a 97dB/W speaker, all else being equal, ie if the power input to a speaker is doubled, the sound pressure level goes up 3dB.My band:- http://www.youtube.com/user/RedwingBand
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