Ampeg B25B amp with ? Cabinet - seeking advice!!

labman · #1 10-09-2010, 08:19 PM

I mostly play guitar but I love messing around on bass so I acquired a bass rig a couple years ago. I picked up an older G&K 700rb and a nice US made SVT-410HLF. Being a softy for old tube amps I decided to let the G&K go when I found an old B25B for cheap in need of repair. The amp is still with the tech getting repaired. But now I have an Ohm problem. The SVT-410HLF is 4 Ohms and this B25B can run at 8 or 16 Ohms. Plus it seems they may not be a good match in regards to watts either. I have read that you want to make sure you have enough power going into the SVT-410HLF. So aside from the Ohm mis-match is the B25B under powered for that cabinet? I will only be playing at home. Someday I could see one of my kids, that both play guitar and (dabble with bass) taking it out for something but that is a few years away.

So I am looking for some advice and opinions.

Should I have the SVT-410HLF rewired for 8 or 16 Ohms?
Or is the SVT-410HLF not a good match anyway in regards to watts?
Would a SVT-15E be a better choice? ( I always loved the tone of the old fliptop B15s)

Any other suggestions. I would prefer to stick with Ampeg though.

Thanks!

Roadkill · #2 10-09-2010, 08:44 PM

I suspect that cab can not be rewired for 8 ohms but can be rewired for 16 ohms.

labman · #3 10-09-2010, 08:48 PM

Yes that seems correct. But is it worth it? It is a good match for this lower power bass head?

thx

Roadkill · #4 10-09-2010, 08:55 PM

Quote:

Originally Posted by labman

Yes that seems correct. But is it worth it? It is a good match for this lower power bass head?

It just won't be super loud or sound like 15's. I actually have a B25B cab with the original CTS square magnet drivers in it that's been rewired to 4 ohms but if I find a B25B head for cheap someday I'll just rewire it back to 16 ohms and be in tone nirvana

.

labman · #5 10-09-2010, 09:26 PM

Well I wonder if the single modern 15 cabinet (SVT-15E) would be a good match or closer to the original (2) 15 CTS cab these amps were paired with. The drivers are certainly completely different.

Roadkill · #6 10-09-2010, 09:49 PM

I don't think it's a question of "matching the amp" but what kind of sound you want that determines which way to go on cabs. Also I wouldn't expect that rig to be loud enough to gig with unless the band has reasonably sane stage volume and you use a fairly efficient cab with it - and you are happy with always having a slightly overdriven "Ampeg" sound.

labman · #7 10-10-2010, 01:34 PM

Well this really is intended to be a play at home amp and used for recording. I know the tone would be very different between and 4x10 cab and a 1x15 cab. It would be cheaper! I just not sure I want to mess with the SVT-410HLF by re-wiring it to 16 Ohms.

I need more opinions! What to do?

anderbass · #8 10-10-2010, 05:39 PM

Here's what I'd do in your situation:

Plug your 4-ohm HLF into the amps speaker jack.

Then insert a bare 1/4" plug into the amps Ext. speaker jack. This converts the regular speaker jack into an 8 ohm that would be much safer to do a quick sound test with your 4-ohm HLF.
(you'll find more info about this 8 ohm conversion trick in several B25B threads here including this one: http://www.talkbass.com/forum/f15/need-help-ohms-head-cabs-695842/#post9736480

Then turn the amp on in standby mode and let it warm up for 5 minutes, then flip your standby switch and play the amp for no longer than 2 or 3 minutes just to see if you like that cabs sound with your B25B or not. If you do, rewire your HLF to 16 ohm, If you dont you now know how to safely run any 8 or 16 ohm cab you like better.