• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

[Ampeg B15R] Following Jess Oliver's advice...

T

Triboost

Aug 26, 2011
25
0
Beautiful Midwest
#1
Well, I'm finally getting around to doing some long-planned upgrades to my '90s-era B15r. Would like to put a new speaker in it first. Any suggestions?

I seem to remember Jess Oliver recommending a 4 ohm hi-wattage as a suitable replacement. Has anyone had good experiences with a particular brand/model?

Ultimately, I'd like to mod the baffle as well to match the classic '60s porting.... I know that's another kettle of fish though. (Wish some enterprising soul would sell pre-cut ply replacement baffles for these cabinets... or at least provide a cut-out template.)

Fyi, I use this amp solely for recording - it never leaves the studio. Lots of basses run through it, mostly passive pickup 4 strings like Precisions, JBs, and the occasional oddball (I've got an early '70s Epi hollowbody that loves this amp).

Any & all advice eagerly appreciated! Thanks!

Aj
 
#4
4 ohm thing: there are way more speakers to choose from that are 8 ohm, and while Jess did like the 4 ohm thing, I find it kind of tightens tube amps up in a not-good way. They still sound great, but I find them a little too tightened up and less responsive by comparison with one running regulation.

The cab, however, I've heard is pretty easy to mod the baffle because it unbolts and comes right out. That might be cool. But I wouldn't bother with recreating the double baffle. The double baffles are cool, but there's nothing special about porting that way that can't be accomplished with a modern port design. And www.fliptops.net will make you any discontinued Ampeg cab or wooden part for an Ampeg cab you want. I would get one or two ports that can fit on the baffle and tune them as needed if you go that route.

Speaker, I would either leave it or possibly try an Eminence Kappalite 3015 or Faital 15PR400, but they're mucho bucks. The usual speakers recommended for those cabs are the Eminence Beta or Delta 15a's, but I think at best they'd be a lateral move from the stocker.

I don't know bro...from the sound of your post, I'm getting that you're happy with it as is and are just looking to tweak a little more performance out of it. Only problem with that is it'll change the sound, and it could go either way whether you like it or not. OTOH, your mods aren't really destructive if you keep the original baffle in a safe place and don't drill any more holes, but I always go by the saying my dad originally coined..."If it ain't broke, don't fix it."
 
  • Like
Reactions: GBlake and Gianni "Orlandez" Orlati
#8
BassmanPaul said:
I agree with Jimmy's entire post. I disagree with Jess's thinking on the 4Ω change. It goes against everything I learned about tube amps. Tubes last longer and sound better when they are matched to the load.
Click to expand...

+1 Everyone I've had private conversations with here on TB like David and Coreyfyfe don't recommend the 4 ohm conversion. I just go with a really efficient 8, perhaps a neo if you can afford it.

Ric
 
#9
Wow, that's quite a consensus! Maybe I should leave it stock. I guess I'm just curious what this thing would sound like with a more capable speaker and the "intended" cabinet baffle.

I also must admit - I very much like to tinker and change things up every once and awhile. :hyper: Since this is totally reversible, it appeals to the modder in me.

MattZilla, I would definitely consider trading you for that B15n if you lived in my neck of the woods (Michigan)! (Which I see, you sadly do not...)
 
#10
Sub'ed to this thread!

I have a B-15R also and have also considered modifications - in particular to get it to sound the same as a B-15N.

That said, Triboost, I have to ask: I can see why you might want to do the porting mod - so as to get the B-15N sound. But, if you're using it solely in the studio, why would you care about doing the 4 ohm speaker mod?

My understanding of the purpose for changing to a 4 ohm speaker is really to, essentially, get more clean volume out of the amp. And for studio use, why would you want to do that?

My question to those who recommend against this: Have you heard a B-15R with this mod, to base your recommendation on? Or is the recommendation based on other experience? (@BassmanPaul: the amp does have a 4 ohm setting - intended, of course, for use with an extension cab - so I don't *think* there would be an issue with running the amp with an impedance mismatch.)
 
  • Like
Reactions: punchclock
#11
What I have thought about doing is get an 8 ohm replacement speaker that is intended for use in a ported cab, then also get a piece of suitable wood to replace the original front piece, and port the new front like a B-15N, install the new speaker, and then just swap out the whole front wall of the R.

The question that I haven't seen an answer for is: Will that then sound JUST like a B-15N?

Also, not directly related, but in case you don't know, the amp has a switch on the front to switch between 60W output and 100W output. But, according to the owner's manual, you can also switch it to the 4 ohm setting on the back (and the 60W setting on the front), and it will output 40W. So, even the owner's manual recommends an option that involves an impedance mismatch.
 
#12
I use my B14R with a 4 ohm cab quite often, it sounds great!
different, but still great! I just use the head only.
I am considering the double baffle thing, but have not really been so inspired by what I've heard from the B15N's that I've played.
the R pretty much nails any B15 tone I've tried.
Then again, I've only had mine for a week, so much remains to be heard.
 
#13
StuartV said:
Also, not directly related, but in case you don't know, the amp has a switch on the front to switch between 60W output and 100W output. But, according to the owner's manual, you can also switch it to the 4 ohm setting on the back (and the 60W setting on the front), and it will output 40W. So, even the owner's manual recommends an option that involves an impedance mismatch.
Click to expand...

The lower power setting, 60W turns off two of the power tubes. This creates an impedance mismatch. If you set the impedance switching the back to 4 ohms and connect an 8 ohm speaker, the impedance mismatch is more or less corrected and you will get 60W. If you set the front panel switch to 60W and leave the impedance switch at 8 ohms, with an 8 ohm cab connected, there will be an impedance mismatch and the amp will only put out 40W.

Hold on to your hats because there's more. If you set the front panel switch to 60W and set the impedance switch to 8 ohms BUT connect a 4 ohm cab (or two daisy chained 8 ohm cabs) the impedance is also matched. SO you get 60W out with two cabs.
 
#15
I'm not sure if porting a B-15R like a double baffle cab will make it sound like a B-15. People that have tried it like it. The thing about the double baffle design, is that it works with the power level if the B-15N's. Too much power and it doesn't work as well. I'm not sure where that cutoff is. It could be that 100W is fine, I just haven't tried it.

Also as for Jess' advice on using a 4 ohm speaker on the 8 ohm tap, he found that it wouldn't harm the amp. This has to do with the design and the transformers. On some amps you can do this, on some amps you can't. It isn't blanket advice that applies to all amps. This may or may not apply to the B-15R. It's a different amp design with different transformers. So you have to be careful. If people have tried it and it works without overheating the transformer or burning up the tubes prematurely, then there should't be a problem.
 
#16
:cool:

I had a B15R they are wonderful amps.
I did change my speaker to a mint 80's EV 4 ohm. 15"
I believe it was a 150-200 watt speaker.
It sounded great in the B15R, much better than the original.
Nice head-room, more defined, took longer to breakup.
The only draw-back, the darn amp then weight 127 pounds.
 
#17
Mojo-Man said:
:cool:

I had a B15R they are wonderful amps.
I did change my speaker to a mint 80's EV 4 ohm. 15"
I believe it was a 150-200 watt speaker.
It sounded great in the B15R, much better than the original.
Nice head-room, more defined, took longer to breakup.
Click to expand...
Exactly why I didn't like it ;)

https://www.youtube.com/watch?v=2VoJMUpzAyI

I don't have a B-15R, but this song was recorded with a Guild Starfire into a mic'ed B-15R and no additional processing. Can't think of a better argument to leave it stock. However, adding a port to is a non-destructive mod as long as you get another baffle, so hey...
 
#18
Ah, thanks for the reminder JimmyM. That Beck disc came out right after I got this amp - I remember feeling the opposite of buyer's remorse when I heard Justin Meldal-Johnsen's bass (tracked on a 15R of course).

Actually, your post inspired me to surf over to the Pro forums last night and revisit Justin's mods. Seems like he has done the obligatory tweeter disconnect, and then there's this thread....

http://www.talkbass.com/forum/f15/great-set-tubes-b-15r-209656/

...where Justin mentions always using EL34s, and not liking 6l6s when he tried them. Which are the tubes I have! 6l6s, that is.

So allow me to derail my own thread... I think I'm just going to start by trying new tubes! That should satisfy my mod itch. But which ones? Svetlanas? JJs? Anyone else have decent/real experience with retubeing a 15r?

Here's a quartet of JJ EL34 for $57 shipped... good choice?

http://www.amazon.com/JJ-EL34-Vacuum-Tube-Matched/dp/B003X5J3IO

And also these for $53...

http://www.talkbass.com/forum/f15/great-set-tubes-b-15r-209656/

(Caca, what kind of EL34's did you use?)
 
As an Amazon Associate, TalkBass may receive commissions from qualifying purchases made via links on this site.
#19
The thing about wanting it to sound like a B15N is subjective at best, imho. I've owned two B15N's, a '67, and a '71. They do not sound EXACTLY the same. They sound like B15N's, but not exactly the same. I guess it depends on what era B15N you want. The new reissues even have a front panel switch that lets you choose between a ' 64 and a '67, I believe. Then, of course, if you start tube rolling, that throws in another monkey wrench. My personal fave is the '67 B15N, but my '71 is pretty good also !
 
#20
Triboost said:
Actually, your post inspired me to surf over to the Pro forums last night and revisit Justin's mods. Seems like he has done the obligatory tweeter disconnect, and then there's this thread....

http://www.talkbass.com/forum/f15/great-set-tubes-b-15r-209656/

...where Justin mentions always using EL34s, and not liking 6l6s when he tried them. Which are the tubes I have! 6l6s, that is.
Click to expand...

I like where you are going with this. Especially since it just reminded me that I have a set of matched old Magnavox 6CA7 that were for my V4, which is now gone.

The 6CA7 is a direct substitute for an EL34, correct? So, I should be able to put them in my 15R and set the switch for EL34 bias and be good to go, right?
 

Latest posts

Top Bottom
Back