Reloading a Marshall slope cab... advice requested...

[nofi]

for that money i am sure you could buy a good used cab (not a marshall) with the speaker configuration of your choice.

[Highlander]

I'm keeping that in mind too, Nofi...

I'm not sure I'd like a present range Marshall, anyway, but then again, never played through one...

[bumnote]

Hi

Why dont you ask emminence?
Send them the cab dimensions and they will give you suggestions. I did that when i was looking for a replacement speaker for one of my acoustic cabs
You can get emminence from Blue Aran in Southampton

You could also pose the question to lean business who are ex celestion people and who do deals if you but 4 speakers

[Iome]

Yo could consider the some (Eminence) marshall VBC speakers, they are 100w each and sells, new, for 60€ + vat.

[exiledarchangel]

If I was in a tight budget situation, I'd probably use Eminence PA speakers, they are tough guys and cheap.
Those "little" bastards are in your budget:

http://www.thomann.de/gr/eminence_beta12.htm

[Highlander]

Thanks for those tips, Gents... they are within my budget...

This may seem like a dumb question, but is their an "equation" for speaker wattage...? I am going from "power equations" from my electrical days and watts = power, so a 100w amp needs to be reasonably matched to a set of speakers, or am I missing something here...? As I said, may be a dumb question, but...

[exiledarchangel]

For a 100w amp, I would get at least 200w for the speakers. There is not an equation, but your speaker wattage must be higher than your amps, so they could survive the power!

[bumnote]

For a 100w amp, I would get at least 200w for the speakers. There is not an equation, but your speaker wattage must be higher than your amps, so they could survive the power!

While I agree with you there is another school of thought that says speaker damage is caused by amplifier clipping and you should use a more powerfull amplifier to give a clean signal.

Im not a techie just what I have read 

[Dave W]

While I agree with you there is another school of thought that says speaker damage is caused by amplifier clipping and you should use a more powerfull amplifier to give a clean signal.

Im not a techie just what I have read 

I've read that too. It makes some sense to me, although I'm no techie either. Still, clean signal or not, every speaker has physical limitations, how much heat its voice coil can take, how much excursion its structure can take.

[godofthunder]

"clean signal" LOL

[exiledarchangel]

"clean signal" LOL

I guess you like it dirty, eh?

[rahock]

I always shoot for about a 20 -  25% higher power rating on the speakers than  what the amp delivers. Yes it is true that if you have a seriously underpowered amp you can screw up the signal coming from the amp and blow a speaker. I have never blown anything up like this, but it can happen . In the old days this was something that never happened..... it was always too much power that got got ya 
 
I'd like to hear Psycho Bass Guys take on this....he actually knows what he's talking about whereas I'm just a guy who learned a bit by blowing a lot of stuff up .
Rick

[Highlander]

Again advice received and understood, Gents...

Now into the new year so will get on with the research - hopefully get something in the next couple of weeks...

[Psycho Bass Guy]

I always shoot for about a 20 -  25% higher power rating on the speakers than  what the amp delivers. Yes it is true that if you have a seriously underpowered amp you can screw up the signal coming from the amp and blow a speaker. I have never blown anything up like this, but it can happen . In the old days this was something that never happened..... it was always too much power that got got ya 
 
I'd like to hear Psycho Bass Guys take on this....he actually knows what he's talking about whereas I'm just a guy who learned a bit by blowing a lot of stuff up .
Rick

Don't feel too bad. I've smoked two sets of drivers in my life; the most recent was a pair of horns in some EV SX300's that had already taken a bad hit from lightning so anything would have killed them, but I spectacularly destroyed a pair of Cerwin Vega SL36 subs when an EQ feeding their power amp had a subsonic oscillation in its output and I had a real power amp pushing them, a bridged Crown MA3600. They got so hot, the magnets turned bright blue permanently and the voice coils had vaporized; not burned, not charred, vaporized.

For most instrument amps, ratings of thermal max power are pretty trustworthy, however, since we play bass which is:

a. hard to hear relative to most other instruments and
b.hard for speakers to reproduce relative to most instruments

... we get to deal with mechanical limitations of drivers as well as thermal. With porting, it is quite possible to destroy a 1000 watt rated speaker with less than 200 clean watts below its tuning frequency, which is why it's important to pay attention to the repsonse curves of a subwoofer and not try to get 30 Hz out of a speaker cabinet than has a 10 dB downpoint at 50.

Now that I've added that little wrinkle, I've got some good news for the OP; your cab is sealed. That means that any added lows below its resonant frequency will simply result in less volume below that point, and unless you exceed the speaker's thermal limit (the wattage rating) with continuous power, you need not fear hurting the speakers. As far as the old saw of "underpowering,"  it was only true in the first decade or so of solid state power when poorly regulated amps would often dump all kinds of nasty stuff into their audio output when overdriven and many a speaker got toasted by having an amp with too little power ( and unrealistic expectations of volume).

As far as my personal philosophy on PA and "clean" ss bass rigs, I like to have a large margin of power in excess of the speaker's thermal rating so that I can attenuate on the front end of the amp. There are large transient signals that almost always exceed an amp's maximum input voltage, even if it's only for a few milliseconds, and if you can turn down the amp's input and prevent that, your overall sound will be better and punchier and your amps will last longer.

[Highlander]

Excellent... time to do some spending...