And in what ways do they affect it? Do the different brands rate differently volume wise or is it mainly to do with the 'type' of string?

Thanks.

There's no rule of thumb here.
It's the interaction between your instrument and given strings.
From the instrument's point of view, the tension may be the most important factor.
Too much tension and the instrument will choke.
Not enough and it'll sound weak.
Once you have the optimal tension, the string's construction and materials will change the tone.

Oh ok, so its just a matter of trying different sets until you find one that works for your bass? I'm still trying to find the 'perfect set' for my bass guitar and I change its strings every few weeks :P.

I have some Superflexibles (I think.. sky blue at both ends?) on my upright at the moment that came with the bass (they were just spares that had been used and were lying around on the floor of the shop I bought it from before that), I like the feel of the strings but I've got no point of reference to say whether they are too tight/loose or whether they're dead or not (They do sound dead compared to modern upright bass recordings I've heard, but my laminate bass is also considerably cheaper than those too).

Are there any 'objective tests' to try and determine whether they are the right tension for the bass? I can make some recordings (K&K Bass Max, MXR M80) if anyone could tell from that.

Have you noticed whether or not your sound is acoustically loud enough (i.e. you can hear yourself) while playing a jam session un-amped? This could be a good test too.

Spiro Mittels are a little less tension that the SF's which may or may not result in a louder tone on your instrument. Like francois said, it all depends on what makes the wood vibrate the most (high, middle, or low tension).

I thought the bass sounded quite quiet compared to other basses I've heard at first (though its loud enough to play with a couple of acoustic guitars), in the months I've had it I've heard a few other people play it and it defiantly sounds a lot more comparable to other basses when I'm standing back from it a little in its line of projection. I'm going to take it into uni on tuesday and get the bass playing lecturer there to play it and tell me what he thinks.

Also, the E string sounds quieter and more dull than the others and I've read that the E usually goes first, so I guess I can say for sure that the strings do need replacing.

Do those Spiro Mittels (or Spiro Weichs which I've also read good things about) go by any other names? The only decent looking place I can find to get strings from in the UK is http://www.stringmail.co.uk/dbass.htm and I can't find either of those listed there.

Mittel = german word for medium
Weich = german word for soft, light

You wrote about your E string being weak.
Did your instrument get a good setup with a qualified luthier?
Some soundpost tweaking may help your instrument a lot.
A good bridge is also important.
The tailpiece wire too.
I'd investigate your setup first, then the strings.

On many basses, a heavier E may help to even out the tone. Some basses just may like it. I happen to use a Spirocre 'Stark' E with 'Mittel' A and D with an Obligato G. This seems to work as well as anything I've tried, and I'm not going to go broke trying every string made.

The Spirocore coding is this: Stark (Heavy or Hard), Mittel (Medium) and Weich (Light or Soft).

FWIW, Weich can sound really good and are easy to play, but Mittel will probably be louder on your bass.

The Canadian wins by two minutes.:)

Mittel = german word for medium
Weich = german word for soft, light

You wrote about your E string being weak.
Did your instrument get a good setup with a qualified luthier?
Some soundpost tweaking may help your instrument a lot.
A good bridge is also important.
The tailpiece wire too.
I'd investigate your setup first, then the strings.

Cheers for the clarification. The bass was set up and given a new bridge by a trusted luthier before I got it, the strings were just old because I could have those for free or pay for new ones and I didn't have money for new ones at the time. Its also been to a different luthier for a nut adjustment since I got it and I asked him to check over it to see if anything else needed doing, he said it was all ok, the tailpiece wire looks in pretty good condition too.

What is the difference in volume between mittel and weich likely to be? Will they still be loud enough to play in public (busking etc.) The action is medium high so it occurs to me that being able to play harder on the weichs may counter and loss of volume due to mass. I also play through a PA system a lot of the time so volume is not SO important, I'd just like to be able to play loud enough when I do play acoustically.

What is the difference in volume between mittel and weich likely to be?

Depends on your bass! :)
It may play louder with more tension, or not....

You can do a small experiment:
Detune your strings a half step flat and sharp, and see if the volume gets louder or weaker.
This may give an indication on what your bass would prefer.

Oh yea good idea, don't know why I didn't think of that, cheers.

I really meant more in general though, if you tested it on a wide range of basses and took averages. If its generally a small difference I'd probably get lights.

Hate having to choose strings that I probably won't change for years with no reference to know what I like and don't : /.

Mittels have a reputation of being one of the loudest strings out there. I've tried both gauges on two basses and the weich sounded noticeably weaker. Mittels just get the bass moving better.

Will they still be loud enough to play in public (busking etc.).

I busk in the 42nd street 1 2 and 3 subway platforms sometimes. I can cut through most of the time haha. I sure as hell don't try to solo though :hiding:

Ok, if theres a pretty noticeable difference in volume I'm definitely getting the mittels over weichs, I think pretty much the final question would be how the superflexibles compare to the mittels (on average) volume wise? Oh and the mittels bow ok right? I'm not a bow connoisseur but I like to practice with a bow. Sorry for asking so many questions heh, cheers for helping me though.

Oh yeah and busking rocks :D, I find it even more fun than performing on a stage.. you have to fight for peoples attention rather than being the default center of attention.. its a true test of your ability as a performer.

Do the mittels bow alright? I'm not the best with the stick, but they seem to do pretty well. Once they settle down and lose their edge they bow nicely on my bass.

Alright cool, cheers. I talked to my luthier too and I'll probably take it in to get the strings changed and the setup optimised for pizz volume/tone.

The results of the detuning/uptuning test were quite interesting. When tuned up the E string tone changed completely, it gained a lot of definition but lost almost all bassyness, when tuned down it didn't seem to change that much but the G and D strings seemed to be a little louder. Not really sure how to interpret these results but it was shocking to see how such a little change could affect the tone so much.

Oscar, you may like to read this thread:
http://www.talkbass.com/forum/showthread.php?t=395532

Best regards,
François