Ampeg B25

Started by SKATE RAT, July 22, 2009, 09:47:26 AM

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SKATE RAT

July 22, 2009, 09:47:26 AM
does anyone know anything about these?i cant really find much info.
'72 GIBSON SB-450, '74 UNIVOX HIGHFLYER, '75 FENDER P-BASS, '76 ARIA 4001, '76 GIBSON RIPPER, '77 GIBSON G-3, '78 GUILD B-301, '79 VANTAGE FLYING V BASS, '80's HONDO PROFESSIONAL II, '80's IBANEZ ROADSTAR II, '92 GIBSON LPB-1, 'XX WAR BASS, LTD VIPER 104, '01 GIBSON SG SPECIAL, RAT FUZZ AND TUBES

Dave W

#1
July 22, 2009, 09:58:04 AM
Not much. It was a 50 watt tube head, and I think came with a 16 ohm cab. You can probably find a schematic online somewhere, just check and see what the output transformer is tapped for.

It wouldn't be suitable for a loud gig.

SKATE RAT

#2
July 22, 2009, 10:07:51 AM
i have a B25 and a Plush royal bass tube head (not sure of wattage,uses 4 6L6's) i also have an empty 2X15 cab.i'm curious about runnin' both heads.is it possible? how? why? i'd like more power/volume/balls.is this a good idea.not sure what speakers to get. or i was also thinking to use the 2X15 with the plush and get a 4X12 for the Ampeg B25. would this be louder? do more speakers equal more volume?
'72 GIBSON SB-450, '74 UNIVOX HIGHFLYER, '75 FENDER P-BASS, '76 ARIA 4001, '76 GIBSON RIPPER, '77 GIBSON G-3, '78 GUILD B-301, '79 VANTAGE FLYING V BASS, '80's HONDO PROFESSIONAL II, '80's IBANEZ ROADSTAR II, '92 GIBSON LPB-1, 'XX WAR BASS, LTD VIPER 104, '01 GIBSON SG SPECIAL, RAT FUZZ AND TUBES

Dave W

#3
July 22, 2009, 10:42:07 AM
The best way to get more volume is more speakers. But find a schematic for the B25, see if it's set up for 16 ohms, you want to be careful with that.

Send a PM to bobyoung if he hasn't responded here within a couple of days, he can probably answer your questions.

godofthunder

#4
July 23, 2009, 05:23:41 AM
 I rehearse with one of these, great sounding little amp !
Maker of the Badbird Bridge, "intonation without modification" for your vintage Gibson Thunderbird

godofthunder

#5
July 23, 2009, 06:15:48 AM Last Edit: July 23, 2009, 09:59:20 AM by godofthunder
I use a Whirlwind A/B box when I run two heads. Two inputs one output to the bass works great, old school Bi amp.
Maker of the Badbird Bridge, "intonation without modification" for your vintage Gibson Thunderbird

godofthunder

#6
July 23, 2009, 09:59:53 AM
Quote from: Dave W on July 22, 2009, 10:42:07 AM
The best way to get more volume is more speakers. But find a schematic for the B25, see if it's set up for 16 ohms, you want to be careful with that.

Send a PM to bobyoung if he hasn't responded here within a couple of days, he can probably answer your questions.
I have a original 2x15 cab it is 16 ohms.
Maker of the Badbird Bridge, "intonation without modification" for your vintage Gibson Thunderbird

Dave W

#7
July 23, 2009, 12:55:27 PM
Quote from: godofthunder on July 23, 2009, 09:59:53 AM
I have a original 2x15 cab it is 16 ohms.

Does the head have taps for 8 and 4 ohms? That would affect what he might be able to run. I haven't seen one in so long.

SKATE RAT

#8
July 23, 2009, 07:29:41 PM Last Edit: July 23, 2009, 08:25:27 PM by SKATE RAT
ok,i've never used the head. i got it with no tubes. so i'm gonna take both this and my plush to get re-tubed etc.(hopefully i'll get a better deal)but it has been modded there are 2 extra jacks.not sure how its wired.since the 2X15 cab i have has no speakers i could just restore it to stock.and get the correct speakers.the whole ohm thing confuses me ???i read that the B25 can run 1 2X15 cab at 16ohm or 2 cabs at 8ohms. does this mean each speaker is 32 ohm? i know the 10" s in my SVT are 16 ohm  not sure about the 15" can some one please explain the ohmage thing and how it pertains to wattage and volume.  from what i can tell about B-25's people say they sound great and are pretty loud and mine is an early one from N.J.
'72 GIBSON SB-450, '74 UNIVOX HIGHFLYER, '75 FENDER P-BASS, '76 ARIA 4001, '76 GIBSON RIPPER, '77 GIBSON G-3, '78 GUILD B-301, '79 VANTAGE FLYING V BASS, '80's HONDO PROFESSIONAL II, '80's IBANEZ ROADSTAR II, '92 GIBSON LPB-1, 'XX WAR BASS, LTD VIPER 104, '01 GIBSON SG SPECIAL, RAT FUZZ AND TUBES

Dave W

#9
July 23, 2009, 11:03:47 PM Last Edit: July 23, 2009, 11:23:27 PM by Dave W
It's a tube amp, the watts will be the same regardless of whether it's 16 or 8 ohms. More speakers will increase the volume.

Edit: (and a Disclaimer: I'm not an amp guy)

From a schematic I found online, it looks like a 16 ohm plus an out for an extension cab which would need to be 16 ohm, making an 8 ohm load overall if you're running a second cab. But it also looks like it can probably be easily modified by a qualified amp tech to run 8 ohm cabinets.

SKATE RAT

#10
July 24, 2009, 05:44:04 AM
what would be the benefit of running an 8 ohm cab?
'72 GIBSON SB-450, '74 UNIVOX HIGHFLYER, '75 FENDER P-BASS, '76 ARIA 4001, '76 GIBSON RIPPER, '77 GIBSON G-3, '78 GUILD B-301, '79 VANTAGE FLYING V BASS, '80's HONDO PROFESSIONAL II, '80's IBANEZ ROADSTAR II, '92 GIBSON LPB-1, 'XX WAR BASS, LTD VIPER 104, '01 GIBSON SG SPECIAL, RAT FUZZ AND TUBES

godofthunder

#11
July 24, 2009, 05:47:35 AM
Quote from: Dave W on July 23, 2009, 12:55:27 PM
Does the head have taps for 8 and 4 ohms? That would affect what he might be able to run. I haven't seen one in so long.
I'll have to check on Monday, the amp is at the rehearsal studio. The cab is 16 ohm so I would guess the 2 15's are  8 ohm in series.
Maker of the Badbird Bridge, "intonation without modification" for your vintage Gibson Thunderbird

Dave W

#12
July 24, 2009, 08:53:16 AM
Quote from: godofthunder on July 24, 2009, 05:47:35 AM
I'll have to check on Monday, the amp is at the rehearsal studio. The cab is 16 ohm so I would guess the 2 15's are  8 ohm in series.

That's what it looked like from this schematic: http://www.drtube.com/schematics/ampeg/b25-jp.gif

Dave W

#13
July 24, 2009, 08:56:47 AM
Quote from: SKATE RAT on July 24, 2009, 05:44:04 AM
what would be the benefit of running an 8 ohm cab?

No particular benefit with a tube head, it's just that today you don't see many 16 ohm cabs.
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