Ohm'age :) ampeg pf800 & pf115he

[Wonky2]

Hi folks

Can someone please confirm if the amp and cab i plan to buy is correctly matched for best performance?
(Edit: i just read the sticky on impedance, very good, but I'd still like a confirmation from anyone who knows ..... . )

I think i understand but want to be sure.

I want to buy a new amp and cab to upgrade my ashdown mag400 and mag4x10 cabinet.
I want to switch to a smaller setup and a 15" speaker.

I recently tried an ampeg b200r rocket bass combo and i just loved the tone. I don't think this would be enough to gig with.

So I looked at the portaflex gear. I hear the pf500 has too many issues and is prone to failiure, but i also read that the pf800 is much better. I don't need 800w at all but I don't want to under power and with the 500 being crud I'd better upgrade ?

So, the question is : the pf800 is 800w at 4ohm's..... The pf115he flip top cab runs at 8ohms....
Is this compatible ? I assume it will just run the amp at half power ?
Is that right? Or do I need a 4 ohm cab?
I only want to use the one 15" cab.... Not planning on adding any others....

Sorry I'm just confused and I don't want to order the wrong gear !

Does anyone have any experience of this set up and have any comments?

There nothing at all wrong with my ashdown gear but I want to switch to a 15"cab and go a bit smaller, plush i just love that classic retro look of the flip top portaflex gear. The sound from that rocket bass ampeg was mega.im using a jazz with flats and love that ampeg tone.

Edited October 5, 2014 by Wonky2

[Wonky2]

Nobody have any comments on this then ?

[JTUK]

I think the 800 amp into a 8ohms cab will 'choke' the amp down to around 500w...
so that is manageable for the cab. Not ideal but the PF500 doesn't sell itself
so you must be aware of over driving. Ampeg ...like a lot of other cab makers
don't see the point of overs-speccing their drivers from a power handling POV
so you just need to make sure you don't drive the cab hard.
I hope you don't plan to use effects in this situation as that can mask a chassis
that is struggling.

Sound-wise, I liked the sound from a PF500 and PF15 in the shop... and I think
a PF500 and Ampeg PF can would work as a match-up, but with the known issues
published here, who would take that chance..??

The only thing I'd say is, my demo in a shop is a world away from a lIve gig, sound-wise
but how will you ever know unless you gig it..

[Lozz196]

In theory it should should work, but as above you`ll need to make sure you don`t push too hard. Personally I can`t see how the 400 watts or so into a 450 watt cab wouldn`t be enough, though I suppose it depends on type of band/genre/other instruments etc. I probably wouldn`t use that set-up in a metal band competing against 412s but would think on it being fine in most other situations. Like JT I loved the sound of the PF500 into the 115, really nice Ampeggy sound.

[Wonky2]

Thanks for the replies guys, really helpfull.

I want the practicality of the flip top, I'd be happy to use the pf500 if it were robust but that doesn't seem the case.

This is what brought me to the pf800 option. You would think being a "ports flex series" ampeg would make a cab matched to the amp it's designed to screw to the lid?

The music isnt metal or rock, more like .......? Squeeze in an odd sense ?? Think tempted.....

I really want to go with the pf series, but I'd be wary using the 800 amp head if the cab is going to be getting pushed?

The ampeg literature says the pf115he cab is : impedance: 400 W RMS power handling @ 8 Ohms
The ampeg literature for the pf800 says : 800W @ 4 ohms, 400W @ 8 ohms,

So I guess this is ok , what's your veiw having seen the data above?

Edited October 5, 2014 by Wonky2

[JTUK]

I don't accept absolutes like 400w into a cab... as there isn't a practical way of measuring it.
Same as an amp being driven three quarters of the way up on the dial...
What does that equate to..??? so I tend to use my ears to gear when a cab is struggling
and because I had such crap gear when I started, I always like to have some headroom
left in cabs...
So...I think you'll be find as long as you aren't getting into fights with shed bulders and shredders
and for most pub gigs, I'd expect the PF series to do well enough. I prefer the PF amp to the SVT
3 and the PF15 was nice warm sounding. Whether it has enough bite I'll never know but the core
sound is there, IMO.

[Wonky2]

Thanks

So, what your saying is its ok but don't push it ?

I agree with what your saying about having the luxury of a littler more headroom in the cab, I'd be more comfortable with that really...

But just to be clear and put this to bed, am I right in thinking that when run with just one 8ohm speaker this amp with for all intent and purpose simply be a 400w amp ? The cab is rated to 400w, so yes that's cutting it fine without the extra headroom, but its likely this set up with just the amp and one cab will be all I will ever use.....
I'm not bothered that the amp is only achieving half its potential, but I am concerns rend that the cab will be runs at full load?

Wish ampeg made this really simple and made an appropriately sized/ rated can for the amp that's designed specifically to go with it !!!

I'm itching to press the buy button but just so not convinced with the amp / cab combination and the ratings of each.

[xgsjx]

I say push it. Use your ears & if it starts to sound like the cab is struggling, then back off a touch either on the low end or the volume.

[Wonky2]

Suppose this answers the question

http://m.youtube.com/watch?v=chn7Z_xEKIQ

I'll get it order tomorrow

[Wonky2]

Xgsjx... Your right mate, I've always played it by ear with these things, guess I just got hung up on the whole impedance issue whilst on the brink of spending some cash

[JTUK]

Yep, exactly that...don't push it.
I think you could get into trouble in a loud band and if you get that gig,
add another cab. But if you aren't loud, you'll be fine.

Also, bare in mind that your volumes on your dials doesn't mean much.
They use to say that Marshals were as loud as they were going to get
anywhere from 4-5 to 11 on the dial...
Use your ears.. which is a good thing to do with every rig, IMO.

[Wonky2]

Aggghh I'm just so hung up on this amp.!!!!!!

I want it, I like the ampeg sound, I just can't bring myself to click the "go to checkout" button..........

The lack of head room in the cab and the amount of failures and broken pf series amps i keep reading about, I'm just not convinced.

I wonder if I would be better sticking with the ashdown mag400 which I have, but maybe trying a 15" cab instaed of a 4x10, plus I'm not even sure my current set up is right??? The mag400 is 500w at 2x 4ohm cabs, but I am just running one 8ohm 4x10 which is just rated at 8ohm 300w.......

One thing i do know is that the mag400is built like a tank, I've never had a single issue with it.

Please , some one, convince me !

[JTUK]

Mag 400 is 500w @2 x 4 ohms..??? are you sure?
I'd think it would do 500 into a 4 ohms load, but to run that, you'd either
have 1x 4 ohm or 2 x 8 ohms.

If you have been running a 300w 8ohm cab..... then you will be ok in the same band
if you run the PF800 into the 8ohms portaflex. You can pair up another 8ohms cab at a later point if you need
to.
The only reason people suggest the PF800 is that it doesn't appear to have the history of failures of
the PF500. Why Ampeg allowed the PF500 issue to fester and continue is beyond most people
when they should have pulled it ages ago, IMO.
Great sounding little amp, from what I've heard, but not helping the Ampeg name when threads pop all
over the place pointing out a pretty common issue, it seems.

[Wonky2]

Thanks jt,
Yes I'm wrong with the 2x4ohm thing.....

So, what your saying is, with the mag 400 , if I find a 4ohm 15" cab I'll get 500w.............

I need to draw a line and make a decision....... After... The ampeg set up will set me back £730, it gets me that great ampeg tone but a whole heap of paranoia around reliability and crap out.....

The main idea for a change was portability, I supose I can get by with a good set of castor on the ashdown gear?

I rehearse tomorrow and I think there is an ashdown combo of some sort with a 15" speaker in it.... If it runs at 8ohms I will try daisy chaining it off my 4x10, this will give me two 8ohm speakers and should give me a taste of the ashdown at 500w full power..... Right?

I'll give it a try , I still want the ampeg gear and the cash is burning a hole in my pocket but I'm loathed to rush into it.... If it was renound as a reliable amp and the cab was better matched I'd be all over it.

Appreciate your comments and patience, this isn't easy.

[xgsjx]

Don't get so caught up on the wattage. That's not where volume comes from.

If you get a 4Ω & an 8Ω version of the same cab, the difference between the 300 & 500 watts is 3db. If you run a single 8Ω cab & then add another the same, you get a 6db increase.
To get double the volume you need 10 times the wattage into the one cab.
The best move is to get the most efficient cabs that you can that have a sound that you like.

[JTUK]

I'd get the amp with the sound you want and an 8 ohm cab and that is your default rig.
If you get the PF800, that assumes you can get 800 int 4 ohms..and around 475 into 4.
Cab impedences are nominal so that is why you don't really know what your amp is producing
and all your ears can tell you is that it is 'loud'.
If the PF800 and PF115 is what you want to hear, then get that and bare in mind that the cab is
not upto the output of the amp.
Since you aren't in a loud band, you'll have to keep an ear out for any stressing of the speaker
which should be easy. Maybe make a note of a position on the dial that you NEVER go beyond
whilst running one cab.... it is likely to be more volume that you need anyway.
Only on large stages and outdoors do you need to be a little more aware as this is where sound
gets swallowed up ...and that is when you might like the extravagence of another cab to get potentially
800watts/full power. Depending on the amp... you may find it goes in to distortion before then anyway..
but we are talking about VERY loud. As long as you aren't going up against a very loud/deaf gtr,
I think you'll be ok enough to hear when the rig is struggling. At that point, back off the volume a bit
and tell the rest of the band to do the same. It is likely at that point the audience is getting blasted as well
so no bad thing to turn down anyway..IMO.