B25

[Bunny Boils]

I was just wondering if I could put in my own comments about some of the various comments I see, concerning the Ampeg B25? My 1969 B25 has been recently serviced, and mildly modified to accept a single 8 ohm load on it's own, or two 8's together. The 16 ohm tap has been left alone. I only need one speaker output. This way, I don't need a "dummy plug" or any of that nonsense. With two 6550's, and a solid-state rectifier, this sounds much better than my old Bassman 100. This amp doesn't sound like a an SVT, or any of the Ampeg "V" family amps. That's not what this amp is about.
I use a modern SVT 4 x 10" HE box under it, and a '69 Telecaster Bass, with a single Rio Grande high output pick-up, and an older SansAmp. This set up is fine, in the clubs I play in, and you always have an out front second signal option, in a larger room.I'm using it with the upright on Friday evening.

 

[michael brown]

I have a 69 b25 as well but still has the factory tube configuration. How do the 2 6550’s and solid state rectifier sound ..?? As opposed to the 7027 ? And tube rectifier ?

 

[Bunny Boils]

I have a 69 b25 as well but still has the factory tube configuration. How do the 2 6550’s and solid state rectifier sound ..?? As opposed to the 7027 ? And tube rectifier ?

The 6550's were just a personal choice. I've had good luck with them in other amps I've had. The solid state rectifier really does help reduce sag, and give you just a bit more usable voltage, although this is not always a popular choice for guitar players. You have to make sure all other components can take the little bump of extra current with the SS option, and should only be tried with new tubes and caps, especially on an amp of this vintage.The way this amp is set up now sounds great, but this is not an ideal set up for long power tube life.

 

[coreyfyfe]

How hot does the PT run with the 6550s? I had a V4 modded to run 6550 and it ran pretty toasty, and I've picked up a few since (plus a B25B) which I keep stock with 7027A. Now that 7027A are in current production from multiple sources, and given that a B25B doesn't run them as hard as a V series amps, I think I'd probably stick to stock.

I rewired my output taps to separate jacks as well, I can run a single 8 ohm cab or run off the 16 ohm tap with a palmer cab merger for two 8 ohm cabs. Great setup for moderate volume gigs.

How do you like it with upright and what pickup/preamp are you running? I tried mine with my upright when I had an underwood pickup installed and it was a mess of feedback, but a lot of that is the underwood I think. I've got a full circle on one bass and realist lifeline on the other, I haven't really had a shot to run them with the B25 though.

 

[Bunny Boils]

How hot does the PT run with the 6550s? I had a V4 modded to run 6550 and it ran pretty toasty, and I've picked up a few since (plus a B25B) which I keep stock with 7027A. Now that 7027A are in current production from multiple sources, and given that a B25B doesn't run them as hard as a V series amps, I think I'd probably stick to stock.

I rewired my output taps to separate jacks as well, I can run a single 8 ohm cab or run off the 16 ohm tap with a palmer cab merger for two 8 ohm cabs. Great setup for moderate volume gigs.

How do you like it with upright and what pickup/preamp are you running? I tried mine with my upright when I had an underwood pickup installed and it was a mess of feedback, but a lot of that is the underwood I think. I've got a full circle on one bass and realist lifeline on the other, I haven't really had a shot to run them with the B25 though.

The transformer actually doesn't take much more heat like this, but the power tubes do. I had a V4 with 6550's. Yes, they like to run hot, but who wants cold toast? 7027a's are back, and are recommended, but you do have a choice.
As for the upright, I did have to suffer through some howling, until I get a bass EQ pedal, and a dual band compressor pedal, both in set and forget mode, at the beginning of the evening. Sometimes I use a SansAmp, and sometimes not. The pick-up is a Fishman, and takes a bit of getting used to, and positioning experimenting to get the best results.

 

[Raw N Low]

Love the B25. Has a tone similar to a modern SB-12 or B18. Either way, sounds like a fliptop in a head package.

 

[Bunny Boils]

Love the B25. Has a tone similar to a modern SB-12 or B18. Either way, sounds like a fliptop in a head package.

Yes. That's pretty much it. I have a battered, retired '64 B15N, and the B25 top sounds quite the same, especially through the flip-top single 15" cab, but with just a bit more shove. It's pretty convincing with a modern 4 x 10" Ampeg SVT speaker cab under it. Not real loud, but small club useable. It has Ampeg tone and character, and at a nice weight for an Ampeg, especially if you've ever owned an SVT, or V4 head or cab!

 

[Ric Vice]

Love the B25. Has a tone similar to a modern SB-12 or B18. Either way, sounds like a fliptop in a head package.

Very interesting, I can see where the SB-12 and B25 would sound alike because they are both using 12AX7's in the preamp, correct? I've never really played a B-18N so I don't know

quite what it sounds like.

 

[Rockbobmel]

I had one back in the day with 2 x 215 B25 cabs with JBLs. Nice amp, good sound, not a lot of headroom.

 

[Bunny Boils]

I had one back in the day with 2 x 215 B25 cabs with JBLs. Nice amp, good sound, not a lot of headroom.

Well, that's like going through the Ampeg family. The B15N sounds great, but only has about 25 watts stock.
The B25 can be coaxed to throw about a moderate 70 useable watts in a small room, but you'll need a modern
4 x 10", as a 15" won't cut.
A V4 should get you through any night, but is very heavy and an SVT is usually way too much.
I've used them all. Some were too much, and others were just right. You can get away with a B15N, with no drummer. Why would you ever need 85 lbs of tubes, to fill a room of 50 people?

 

[coreyfyfe]

Very interesting, I can see where the SB-12 and B25 would sound alike because they are both using 12AX7's in the preamp, correct? I've never really played a B-18N so I don't know

quite what it sounds like.

The B18 and B25 share a power amp design. There are a few minor variations here and there but very similar. Wouldn’t surprise me if they used the same transformers as well. Very similar sounds across the B/SB range.

 

[Raw N Low]

Very interesting, I can see where the SB-12 and B25 would sound alike because they are both using 12AX7's in the preamp, correct? I've never really played a B-18N so I don't know

quite what it sounds like.

The B18 and B25 share a power amp design. There are a few minor variations here and there but very similar. Wouldn’t surprise me if they used the same transformers as well. Very similar sounds across the B/SB range.

Thanks Corey. I was going to page you for clarification on the matter. Another amp that is somewhat similar but very different is the Ampeg V2. Much more conventional in the ohm settings and a bit more grit.

 

[Ric Vice]

One question, since the B-18N uses 6SL7’s in the preamp and the B-25 uses 12AX7’s dosen’t it sound different. When I owned a SB-12 I really preffered the tone of the B-15N
I realize that there were other differences the cabinet etc. Just wondering.

 

[Ric Vice]

I have a question for our experts.
Since I recently had Killer Vintage here in St.Lous, replace the tube set,
Bias my B-15N(C) and install a rebuild JBL D-130. Should I be breaking in the speaker and tubes for a few weeks before I use it for a full on session?

 

[Bunny Boils]

One question, since the B-18N uses 6SL7’s in the preamp and the B-25 uses 12AX7’s dosen’t it sound different. When I owned a SB-12 I really preffered the tone of the B-15N
I realize that there were other differences the cabinet etc. Just wondering.

I find every pre-amp tube does roughly the same job, but every damn one of them sound slightly different.
You could replace a 12AX7 with the exact same tube from the same manufacturer, and somehow, it sounds different. I had the 6L6's replaced on my B15N, and it changed the tone slightly. I also recently had a 400 watt 15" Eminence driver re-coned, and now I can't stand the sound of it. Parts are a strange thing. New parts should always be an improvement, but occasionally, they have an annoying characteristic.

 

[disssa]

I love the sound of my 73er B25B.

I compared this amp with a B15N and they sound very similar. It's amazing how loud the amp can be!

 

[Bunny Boils]

I love the sound of my 73er B25B.

I compared this amp with a B15N and they sound very similar. It's amazing how loud the amp can be!

Yes. There were no shortcuts anywhere on these amps. Look at the size of the transformers, for an amp that runs only two power tubes! This looks like a Magnavox from about 1972-'73. Very tidy. It looks almost exactly like a slightly smaller version of my V4, but with a logo on, and at 1/2 the weight! I've owned just as many factory Ampegs that had a logos on, as off. I guess they didn't put them on all models until after 1972 or so?

 

[petrus61]

Here’s mine with matching 215. Scored at an estate sale and lived its life as a PA for an auctioneer, according to the son of the original owner. Currently not functioning. Won’t turn on without immediately blowing a fuse upon power up, so I don’t turn it on! Would love to have it brought back to life at some point but am having a hard time finding anyone reliable to take a look at it (Hudson Valley/Capitol District NY if anyone can steer me the right way). It’s been a while since I had the cab open so I don’t recall if they are JBL or not, but everything is essentially stock IIRC.

 

[Bunny Boils]

Here’s mine with matching 215. Scored at an estate sale and lived its life as a PA for an auctioneer, according to the son of the original owner. Currently not functioning. Won’t turn on without immediately blowing a fuse upon power up, so I don’t turn it on! Would love to have it brought back to life at some point but am having a hard time finding anyone reliable to take a look at it (Hudson Valley/Capitol District NY if anyone can steer me the right way). It’s been a while since I had the cab open so I don’t recall if they are JBL or not, but everything is essentially stock IIRC.

View attachment 3350644

That looks like an excellent score, that can act as furniture, until you find a repairman. Usually Ampeg techs are the best to see, but I've convinced a few competent Marshall/Fender tube techs that an amp is an amp, and that my Ampeg is busted, and it ended with encouraging results. Maybe you don't want to take that chance, but ask around, and I'm sure a name will surface. Remember, Ampegs were built pretty tough, and every part can be sourced, serviced or replaced, and not often do the transformers need to be replaced. Here in Ontario Canada, fine examples like this are sure getting harder to find, especially with that matching 2 x 15" box!
Now, do I hear 30...35...going once...

 

[petrus61]

That looks like an excellent score, that can act as furniture, until you find a repairman. Usually Ampeg techs are the best to see, but I've convinced a few competent Marshall/Fender tube techs that an amp is an amp, and that my Ampeg is busted, and it ended with encouraging results. Maybe you don't want to take that chance, but ask around, and I'm sure a name will surface. Remember, Ampegs were built pretty tough, and every part can be sourced, serviced or replaced, and not often do the transformers need to be replaced. Here in Ontario Canada, fine examples like this are sure getting harder to find, especially with that matching 2 x 15" box!
Now, do I hear 30...35...going once...

I did get it cheap enough (practically gave it to me) to where I wouldn’t mind spending a couple hundred to get it serviced, I just don’t want to hand it off to any guitar store that happens to have a kid in the back room with a dirty soldering iron just dying to test his/her newly acquired skill on my amp. Someday!