Trying to understand speakers
- Thread starter Coma
- Start date
Dave Locher
New member
Re: Trying to understand speakers
Amen to that! I swapped my speakers a year or two ago and quickly went through 4 different models from two different companies before I came up with "better" (to my ears) than what I started with. Each change totally altered my sound even though they were all supposedly similar speakers.
Amen to that! I swapped my speakers a year or two ago and quickly went through 4 different models from two different companies before I came up with "better" (to my ears) than what I started with. Each change totally altered my sound even though they were all supposedly similar speakers.
ehdwuld
A Ficus
Re: Trying to understand speakers
My Belair has a 4-8-16 switch
It was on 4 and I mistakenly thought my 8 ohm speakers were 16 ohms each
I moved the switch to 8 for the 4 ohm load
The tone didn't change
The amp wasn't hurt
I did experiment a bit after I realized my mistake
Single speaker at 8 ohm
Both speakers in series 16 ohm
Both speakers in parallel 4 ohm
No change in tone
Modest change in volume ( single speaker vs dual speakers )
My Bugera G5 wants at least a 8 ohm load
With a 16 ohm speaker
And with an 8 ohm speaker
There wasn't the anticipated volume drop
But the difference in speakers was noticeable
My Belair has a 4-8-16 switch
It was on 4 and I mistakenly thought my 8 ohm speakers were 16 ohms each
I moved the switch to 8 for the 4 ohm load
The tone didn't change
The amp wasn't hurt
I did experiment a bit after I realized my mistake
Single speaker at 8 ohm
Both speakers in series 16 ohm
Both speakers in parallel 4 ohm
No change in tone
Modest change in volume ( single speaker vs dual speakers )
My Bugera G5 wants at least a 8 ohm load
With a 16 ohm speaker
And with an 8 ohm speaker
There wasn't the anticipated volume drop
But the difference in speakers was noticeable
PFDarkside
of the Forum
Re: Trying to understand speakers
Almost all the posts I read about this treat an amplifier like an ideal voltage source amplifier, where voltage stays constant and current is proportional to load impedance. This is true for solid state amplifiers, what we all learned in school, etc.
Tube amps are closer to ideal current sources that will vary voltage with load. There are multiple taps on the output transformer to match the speaker load with the load that the tubes require. Also, if you are thinking it through, a transformer “reflects” the load impedance to the tubes. So as speaker impedance increases, the transformer reflects this as a smaller impedance to the output tubes. Either way, they are expecting a certain impedance, hence the various taps.
As a final “gut check”, ask your self these two questions.
1. On a solid state amp, what theoretical load is fatal? SHORT
-For a solid state amp as you use smaller and smaller loads you are approaching a short, which is a failure condition.
2. On a tube amp, what “load” is fatal? OPEN (we all are taught not to run a tube amp without a load)
-For a tube amp, as you use larger and larger loads you are approaching theoretical Open.
Depending on the output stage design and output transformer design/robustness, some level of mismatch may be ok, or it may not. That’s why I say check with the manufacturer. A doubling of impedance may be ok on a Mesa but not on a Bugera. At some mismatch it will cause damage, so verify what that “safe mismatch” is with the manufacturer.
I just want to point out that the so called “safe mismatch” only applies to Mesa and any other manufacturer that explicitly states this.
Almost all the posts I read about this treat an amplifier like an ideal voltage source amplifier, where voltage stays constant and current is proportional to load impedance. This is true for solid state amplifiers, what we all learned in school, etc.
Tube amps are closer to ideal current sources that will vary voltage with load. There are multiple taps on the output transformer to match the speaker load with the load that the tubes require. Also, if you are thinking it through, a transformer “reflects” the load impedance to the tubes. So as speaker impedance increases, the transformer reflects this as a smaller impedance to the output tubes. Either way, they are expecting a certain impedance, hence the various taps.
As a final “gut check”, ask your self these two questions.
1. On a solid state amp, what theoretical load is fatal? SHORT
-For a solid state amp as you use smaller and smaller loads you are approaching a short, which is a failure condition.
2. On a tube amp, what “load” is fatal? OPEN (we all are taught not to run a tube amp without a load)
-For a tube amp, as you use larger and larger loads you are approaching theoretical Open.
Depending on the output stage design and output transformer design/robustness, some level of mismatch may be ok, or it may not. That’s why I say check with the manufacturer. A doubling of impedance may be ok on a Mesa but not on a Bugera. At some mismatch it will cause damage, so verify what that “safe mismatch” is with the manufacturer.
Last edited:
beaubrummels
Well-known member
Re: Trying to understand speakers
This isn’t entirely true. My old 1973 Traynor YBA 45-watt 2x 6CA7 and my buddies 1968 Park 50-watt 2x EL34 actually put out closer to 90 watts when dimed. My Traynor is louder than my HiWatt DR-103 100-watt. Newer 100-watt Marshalls that have an effects loop often put out no more than 80 watts.
The 15-ohm vs 16-ohm discrepancy is due to the legacy 15-ohm rating used before speaker companies standardized on 16-ohm. Speaker impedance is really just a loose average because impedance actually varies by frequency of program material it’s reproducing.
This isn’t entirely true. My old 1973 Traynor YBA 45-watt 2x 6CA7 and my buddies 1968 Park 50-watt 2x EL34 actually put out closer to 90 watts when dimed. My Traynor is louder than my HiWatt DR-103 100-watt. Newer 100-watt Marshalls that have an effects loop often put out no more than 80 watts.
The 15-ohm vs 16-ohm discrepancy is due to the legacy 15-ohm rating used before speaker companies standardized on 16-ohm. Speaker impedance is really just a loose average because impedance actually varies by frequency of program material it’s reproducing.
