Markbass difference between 8 and 4 ohms.

[Tim1]

This really does not apply just to Markbass amps, but since I used a Markbass.....
I have always been curious as to how much volume difference we actually perceive with a transistor amp going to a different impedance speaker, but have never had the opportunity to test apples with apples, that is an identical speaker with two impedances. Recently one of my students puchased a 4 ohm SWR Goliath4 410, and since I have an 8 ohm Goliath3 410 we put the two side by side and used my Markbass SA450 to drive each one. The 4 ohm bin would receive 500watts, the 8 ohm 300 watts. Essentially there was a minimal volume difference at the same setting, if any at all - barely perceptible and maximum volume without farting out on both cabs was the same. I accept that there might be some minor differences between the pre and post Fender cabs. I also preferred the tone a little at 8 ohms, again could be the cab but very minor. So I guess that what I have done is convinced myself that what all the theorist say is true about decibels and ten time the wattage to get double the volume etc. I will not worry too much any more whether my MB drives 8 or 4 ohms in terms of the volume, speaker efficiency is probably much more important. My point?????? Well, I am a bass player and always curious...

 

[KJung]

This really does not apply just to Markbass amps, but since I used a Markbass.....
I have always been curious as to how much volume difference we actually perceive with a transistor amp going to a different impedance speaker, but have never had the opportunity to test apples with apples, that is an identical speaker with two impedances. Recently one of my students puchased a 4 ohm SWR Goliath4 410, and since I have an 8 ohm Goliath3 410 we put the two side by side and used my Markbass SA450 to drive each one. The 4 ohm bin would receive 500watts, the 8 ohm 300 watts. Essentially there was a minimal volume difference at the same setting, if any at all - barely perceptible and maximum volume without farting out on both cabs was the same. I accept that there might be some minor differences between the pre and post Fender cabs. I also preferred the tone a little at 8 ohms, again could be the cab but very minor. So I guess that what I have done is convinced myself that what all the theorist say is true about decibels and ten time the wattage to get double the volume etc. I will not worry too much any more whether my MB drives 8 or 4 ohms in terms of the volume, speaker efficiency is probably much more important. My point?????? Well, I am a bass player and always curious...

I've done these A/B's quite a bit with 4ohm and 8ohm Epi410UL's ( and a few other 'identical cabs' that happen to have 4 and 8ohm versions). In a solo setting where you are not totally digging in, your description is what I hear. The 4ohm sounds somewhat louder prior to clip or compression, and the low end is more open. You notice it a LOT more with a relatively low power amp like the MB SA450 when slapping. At 300 watts, those peaks can really drive the post EQ limiter circuitry to kick in, causing the top end to sound a bit quashed, and the low end to seemingly 'move in toward the lower mids'. It's not purely about 'volume' IME.

You REALLY notice it when playing in a loud, busy mix where you are digging in more. While the volume difference isn't 'night and day', it's there. However, what you really notice is the response of the instrument (especially when slapping). It doesn't fight you down low, and the top end seems to emerge much more crisply.

However, to your point, three caveats:

1) I notice this on lower power amps, but not higher power ones. For example, the Walter Woods or AI amps that are over 500 watts into 8ohms seem to be able to pretty much drive even a large cab at 8ohm power level. It's mainly an issue of going from 'not enough power' to 'just enough power' (i.e., 300-500 watts).

2) If you aren't pushing the 300 watts to its limits, you won't notice much difference. Until you start really wumping, you won't really notice the extra headroom.

3) This is more of a 'large cab' issue, since even 300 watts is more than enough power to drive a 112 to 'full volume'. However, if you have a high power rated 212, 410, whatever, it can make the difference between sounding OK and sounding great.

IMO and IME!!!!

 

[::::BASSIST::::]

Interesting. Though, I absolutely love the tone of my Epi UL115, I've been put off that I can't get the full power out of my amp. I was even thinking of trying to find a suitable 4 ohm driver, but then I wonder how much that would change the character of the tone (which ultimately I like very much and would rather not change).

However, with my LMII, I find the 8 ohms of the UL115 to be loud enough for the gigs that I do. I've only used the two units together twice but I never went past 10:00 on the master vol. with the gain at 1:00.

For outside gigs I use my 4 ohm schroe 1212R which I am sure is alot louder than the UL115.... though not as 'pretty' sounding.