Why not? It's really similar to the Musicmaster.

I've got a pretty decent onyx pre but I've just never enjoyed the sound of a bass record di. I think I enjoy the "imperfections" of recording an amplified sound with all the characteristics of the room. But maybe I'll do two tracks and split the difference between the mic and di.

It might 'work' but technically speaking, an amplifier's output transformer is designed to work with a certain minimum frequency. If you go below this frequency, the transformer will not appreciate it! The tubes try to deliver power to the load but the transformer can't transmit it, so it gets absorbed as heat and might burn out.

If you look at hi-fi amp designs, the output transformers are much, much larger than the transformers in guitar amps. That's because they are designed for 20 Hz while guitar amplifiers are designed for 80 Hz, the frequency of a low E string. If you have an oscilloscope and look at the performance of a guitar amp at 80 Hz and below, you will see that it's not a good idea to run an amp at frequencies this low.

If the transformer does burn out, replacements are pretty cheap and you only need basic soldering skills to replace it. You could also take the opportunity to upgrade to a nice hi-fi transformer (expensive) and then you'd be the first on your block with a genuine low-power bass amp!

If it ain't broke, fix it until it is.

My low-frequency tests were on the guitar amps like Twin Reverb and Super Reverb, not the bass amps. But if you look at the blackface guitar amps, Fender dealt with the low-frequencies by using a tiny 0.001 uF capacitor to feed the inverter (the old tweed Bassman used 0.02 uF, which is 20x larger). This reduces the low-frequency content presented to the output transformer in an attempt to avoid problems.

The black bassman amps (other than the AA864) used nice, big phase inverter input capacitors. Apparently, Fender had more confidence in the sizing of the Bassman transformers and didn't resort to filtering out the lows.

As for the Bassman 100, it just doesn't have the power of modern solid-state amps. Since they don't have output transformers, solid-state amps don't have any problems with low frequencies. The Bassman 100 is outmatched by the Bassman 135, and anyone who was at the recent SG101 convention knows that the Bassman 135 is a great bass amp! You are welcome to try and use a Bassman 100 for bass, but I know those are great for guitar, a poor man's Showman head.

If it ain't broke, fix it until it is.

The PA speaker vs. guitar speaker issue is another can of worms. The main problem is that monitor manufacturers believe that music only contains occasional peaks, which is definitely not the case for us. This causes them to give their PA speakers a higher rating than they should. Take a look at this short document from JBL:

http://www.jblpro.com/pub/technote/spkpwfaq.pdf

It discusses their methods for power rating and for music reproduction, the amplifier can be rated at double the rating of the monitor speaker (200-watt amp into a 100-watt monitor). But the paper says that for musical instruments, the amplifier should be rated at only half that of the speaker (50-watt amp for a 100-watt monitor). The JBL paper claims that a fully distorting amplifier can deliver double its rated clean power, which is something I've measured in my own experiments.

Part of the problem is that unlike guitar cabinets, monitors contain a crossover network. The crossover itself has a power rating so it can be damaged by excessive power input.

Guitar and bass speakers are different in that they seem to survive well in a 1:1 ratio with the amplifier (100-watt amp for a 100-watt guitar speaker). Since you were given this PA monitor for free, you probably won't be too upset if the tweeter blows. Besides, bassists seem to prefer cabinets with a blown tweeter.

If it ain't broke, fix it until it is.

Last edited: Sep 19, 2013 13:20:39

mbhudson wrote:

I've got a pretty decent onyx pre but I've just never enjoyed the sound of a bass record di. I think I enjoy the "imperfections" of recording an amplified sound with all the characteristics of the room. But maybe I'll do two tracks and split the difference between the mic and di.

You're probably not going to get an ultimate DI bass tone without a transformer based preamp...(something other than the Onyx). That being said, try it. You might like it. I think the last time I recorded, the bass was recorded direct through a Focusrite ISA along with a mic'd Fender Bassman. Sometimes we used a blend of both, once we used just the mic, and another time we ended up using the DI only in the mix. It was surprising how similar they sounded, and with the DI you don't have to worry about mic bleed if you're recording live with a drummer in the same room.

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mbhudson wrote:

I think I enjoy the "imperfections" of recording an amplified sound with all the characteristics of the room.

How do you mic the amp?

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