Amp trouble/ am I wrong?

[Iheartreverb]

I'm using an amp borrowed from a friend in our practice space and I'm just struggling to be heard.

I'm using an Ampeg ba115 against a fender twin and a tiny terror. To me this seems to be the point, the amp just doesn't have enough to compete but want to make sure I'm not wrong.

Next. What would you recommend? I'm looking at a PF350 possibly but I don't (because I have never had to before) understand speaker sizes. Would the same amp be louder through a 4x10 from a 1x15? Is it sending the same signal to 4speakers instead of one? It seems like using a bigger speaker with anything less that 400/600 watts is daft as your under powering the cab, am I right? And why is the "perfect match" cab always 8ohm when the heads are 4ohm, does that not deliver less power?

I understand there's a lot of questions in there but all help appreciated

[Lozz196]

As above. Re ohms, the 4ohm/8ohm thing doesn`t really make that much difference overall. If you use a 500 watts at 4ohm amp into an 8ohm 410 you`ll get 350ish watts and it will be plenty loud enough. Swap to a 4ohm 410, and getting the full 500 watts, it won`t seem that much louder. However keep the 8ohm 410 and add another of the same, that`s where you`ll notice the power/volume difference. The PF350 gives out 250 watts at 8ohms. Into an efficient 410 that should be plenty enough for most gigs.

[gjones]

To make a long story short, the more speakers you have, the louder you'll be. You'll have more volume with a less powerful amp, going through lots of speakers (ie a 200 watt amp going through two 4x10 cabinets), than a very powerful amp going through one speaker (ie a 500 watt amp going through a 1x15 cabinet).

A 100 watt amp through one 15 inch speaker is really not loud enough to compete with a loud drummer and two enthusiastic guitarists. Your amp doesn't allow you to connect another speaker. So your only alternative is to buy new gear if you want to be heard. I recommend buying secondhand as you get more for your money. Plenty of gear for sale on basschat.

[Guest bassman7755]

[quote name='Iheartreverb' timestamp='1393618371' post='2382746']
I'm using an amp borrowed from a friend in our practice space and I'm just struggling to be heard.

I'm using an Ampeg ba115 against a fender twin and a tiny terror. To me this seems to be the point, the amp just doesn't have enough to compete but want to make sure I'm not wrong.

Next. What would you recommend? I'm looking at a PF350 possibly but I don't (because I have never had to before) understand speaker sizes. Would the same amp be louder through a 4x10 from a 1x15? Is it sending the same signal to 4speakers instead of one? It seems like using a bigger speaker with anything less that 400/600 watts is daft as your under powering the cab, am I right? And why is the "perfect match" cab always 8ohm when the heads are 4ohm, does that not deliver less power?

I understand there's a lot of questions in there but all help appreciated
[/quote]

Is your current speaker 8ohm ? if so then your best bet is to add another 8ohm cab - another 15 or a 2x10/2x12. Youl win on two counts: increased efficiency of driving more speakers and being able to tap into the full output of the amp at 4ohm.

Edited March 1, 2014 by bassman7755

[chris_b]

I don't think your combo has a speaker out so you're stuck with an underpowered heavy lump.

What's your budget?

I would recommend at least a 300 watt amp (or save yourself an upgrade by going for 500 watts right now) and a 4 ohm cab (if you're getting a 410 or 212) or an 8 ohm cab if you go for a smaller (115 or 210) cab now with the intention of adding another one to it later.

Don't get the Ampeg PF500, they have a reputation for failing, but the PF350 and PF800's seem to be OK.

You'll get better value for your money if you buy used. There are some great amps and cabs in the For Sale section.

[Iheartreverb]

Thanks everyone. Some really solid advice. I don't have a budget as such but I know for the same price as the pf350 there is loads of options from other manufacturers.

I just wanted to see if I was right in needing to get something new. The Ampeg is only borrowed anyway.

Thanks again, good explanations

[xgsjx]

If you're trying to keep the budget down, then Genz Benz are worth a look just now.
I'd be trying gear out though to see what you like, there's a lot of good gear out there at all sorts of prices.

I would always aim to get an 8 ohm cab unless the one you want is only made in 4 ohm. The difference in volume is so little that it's not worth restricting your future or the extra strain on the amp.

[chris_b]

There is no "extra strain" on an amp running at 4 ohms!

[xgsjx]

[quote name='chris_b' timestamp='1393748367' post='2383861']
There is no "extra strain" on an amp running at 4 ohms!
[/quote]

Running an amp at full load means there's more heat going through your amp's components, which is the trade off.
I'd call that "extra strain".

[Phil Starr]

I'm afraid that in oversimplifying some of the advice is a bit misleading. I'll summarise but you can get more detail here http://www.ultimate-guitar.com/columns/gear_maintenance/making_it_loud.html

Most of the power from your amp is wasted as heat, only about 5% ends up as sound. The amount wasted varies from speaker to speaker. this is reflected in the efficiency of the speaker usually given as how loud it is for just one Watt or dB/W

Some bass speakers give just 92dB/W and the best in terms of efficiency maybe 102dB. Every time you increase the power by 10 you get an extra 10dB and you need about 120dB to match a drummer. That's about 70W through the loudest speaker and 700W through the quietest. As said 300W through an average speaker will be enough.

Size matters but only a bit. A big speaker will be louder than a small speaker if everything else is the same and doubling speakers up gives the same advantage in sound levels as having a big speaker, it's the cone area that counts. However lots of other things like how powerful the speaker magnet is will count too. It's possible for a 12" speaker to be loud enough on its own if it is capable of moving far enough and has a powerful magnet and many 15's will do it on their own too.

If you are using a 100W+ amp in a rehearsal the usual reason for not hearing is that you are standing too close to your amp and it is pointing at your ankles not your ears. Tipping it back and pointing it at your ears will help a lot.

Hope this helps

[chris_b]

[quote name='xgsjx' timestamp='1393754648' post='2383935']
Running an amp at full load means there's more heat going through your amp's components, which is the trade off.
I'd call that "extra strain".
[/quote]

Running an amp at "full load" is what it is designed to do and should not represent a "strain".

[Guest bassman7755]

[quote name='xgsjx' timestamp='1393754648' post='2383935']
Running an amp at full load means there's more heat going through your amp's components, which is the trade off.
I'd call that "extra strain".
[/quote]

Providing the amp is operating within its design parameters, and the amp design has been rigorously tested then its very unlikely to make any difference in practical reliability terms. Typically prototype amp circuits are run at maximum load for hundreds of hours continuously to ensure they are fit for purpose.

[skankdelvar]

[quote name='Phil Starr' timestamp='1393756826' post='2383963']
If you are using a 100W+ amp in a rehearsal the usual reason for not hearing is that you are standing too close to your amp and it is pointing at your ankles not your ears. Tipping it back and pointing it at your ears will help a lot.
[/quote]

Ran a tilt-back 100w Ampeg SS combo like that for years. Did pub gigs too, up against various drummers, a Bluesbreaker combo and a harpist with a Blues DeVille.

If one also aims to get the mids through and doesn't expect much in the way of bottom-end oomph it's reasonably practical, depending on the genre.

[theyellowcar]

[quote name='Phil Starr' timestamp='1393756826' post='2383963']
If you are using a 100W+ amp in a rehearsal the usual reason for not hearing is that you are standing too close to your amp and it is pointing at your ankles not your ears. Tipping it back and pointing it at your ears will help a lot.

Hope this helps
[/quote]

This would be the first thing to do - repositioning the amp and adjusting to account for the directional nature of most bass speakers could be a much cheaper (albeit short term) fix.

[xgsjx]

[quote name='chris_b' timestamp='1393761610' post='2384033']


Running an amp at "full load" is what it is designed to do and should not represent a "strain".
[/quote]
That's what one would hope, but in reality, it doesn't work like that.
As BFM says, "it's like running your car to the red line all the time".

[stubass]

Amp wise, I'd big up a hartke lh500(500w@4ohms and 350w@8ohms). I asked for advice on here and got recommended the lh. Got it for £250 new. Fantastic amp, great clean sound and loud as f***. I run an ashdown 210 and 115 off it (both 350w@8ohms) and it's barely pushed past 5 with loud drummer in a bad mood. Done some recording with it too. The cabs were £100 ish each used. Cheap rig but its up there with the best I've ran. Can just take one cab if it's practice or a pub job too, versatile.

[Handwired]

[quote name='xgsjx' timestamp='1393790801' post='2384418']
That's what one would hope, but in reality, it doesn't work like that.
As BFM says, "it's like running your car to the red line all the time".
[/quote]
Not the same at all.

[xgsjx]

[quote name='Handwired' timestamp='1394001009' post='2386690']
Not the same at all.
[/quote]
How so?

Here's exactly how BFM described the increased current draw when running an amp to it's minimum impedance...

[quote][color=#282828][font=helvetica, arial, sans-serif]Rule # 1 of loudspeaker design: There's no such thing as a free lunch. What you gain with respect to voltage sensitivity with a lower impedance load comes at the expense of increased current draw. To preserve a balance between voltage and current headroom you should avoid running an amp into its minimum rated impedance load.[/quote][/font][/color]
[color=#282828][font=helvetica, arial, sans-serif]Why?[/font][/color]
[quote]Potential for clipping, and heat, which shortens the life of amp components. Think of an amp as an engine. You wouldn't want to drive a car with the RPMs always red-lined.[/quote]
Given that he knows his stuff, I've no reason not to believe him.

[0175westwood29]

[quote name='xgsjx' timestamp='1394002526' post='2386692']
How so?

Here's exactly how BFM described the increased current draw when running an amp to it's minimum impedance...

[/font][/color]
[color=#282828][font=helvetica, arial, sans-serif]Why?[/font][/color]

Given that he knows his stuff, I've no reason not to believe him.
[/quote]

im sorry but really! your never meant to run 2 cabs? with any amp then? if an amp has a min impedance of 4 ohms its fine to run at 4 ohms, the problem would be if you were running said amp at max volume (digital amps not valve) ie everything at 10 and clipping the amp to hell. which to get the volume the op needs would be the problem here.

andy

[LukeFRC]

To the OP....

the other trick is less sexy for us all that love bass gear.... but get the guitarists to turn down a bit....

[Musky]

Bill is absolutely correct in what he says - components that run hotter will have a shorter life.

How much of a difference it's going to make will depend on the amp and how well it copes with the extra demand on it's cooling.

[xgsjx]

[quote name='0175westwood29' timestamp='1394052569' post='2387487']
im sorry but really! your never meant to run 2 cabs? with any amp then? if an amp has a min impedance of 4 ohms its fine to run at 4 ohms, the problem would be if you were running said amp at max volume (digital amps not valve) ie everything at 10 and clipping the amp to hell. which to get the volume the op needs would be the problem here.

andy
[/quote]
No need to apologise.
I (nor Bill) never said that you shouldn't run 2 cabs. I said that running the amp at it's minimum impedance is wearing out the components quicker.
Yes, amps are tested to take the extra strain on the components, but if there's a 4 ohm & an 8 ohm cab & you're only running the one cab, then it's not worth wearing out your amp that bit more with the 4 ohm cab for something you're probably not going to notice.
If you're adding a 2nd cab, then you're gonna hear the difference, so it's probably worth the trade off.

[0175westwood29]

[quote name='xgsjx' timestamp='1394059394' post='2387609']

No need to apologise.
I (nor Bill) never said that you shouldn't run 2 cabs. I said that running the amp at it's minimum impedance is wearing out the components quicker.
Yes, amps are tested to take the extra strain on the components, but if there's a 4 ohm & an 8 ohm cab & you're only running the one cab, then it's not worth wearing out your amp that bit more with the 4 ohm cab for something you're probably not going to notice.
If you're adding a 2nd cab, then you're gonna hear the difference, so it's probably worth the trade off.
[/quote]

Ok so why say it? Just seems to be a way of worrying people who are new to heads and cabs.

Andy

[xgsjx]

[quote name='0175westwood29' timestamp='1394095267' post='2387790']
Ok so why say it? Just seems to be a way of worrying people who are new to heads and cabs.

Andy
[/quote]

Not trying to worry anyone, just pass on information that can help prolong the life of an amp.
Why would you want to not know?

[chris_b]

So all amps should be run at 8 ohms? This is not true.

It is perfectly safe to run an amp at 4 ohms.

I don't advise anyone to run any amp flat out because they don't sound very good if you do that. I don't run mine over about 6 on the master volume, but new amp owners should know if an amp is designed to run at 4 ohms (and they all are) it is perfectly safe to do so and they will not shorten the life of the amp running at 4 ohm at a sensible volume.