B25b cab replacement speakers: Ampeg 86-036-08 (b115e)?

[Fritzren]

Hi, first post, I recently decided to give my chiropractor a raise so I purchased a SVT II pro. I have a B25b cabinet that I inherited for a bad debt years ago. It works fine but I don't think the original CTS speakers are adequate. The ampeg b115e replacement speakers are pretty cheap and that cabinet is rated 200w RMS. Would these be adequate?

I play a fretless jazz and an ibanez 5 string. Rock, country, 90s alternative, punk etc.

Thanks

 

[Fritzren]

This is a great site. I think I found my answer, no.

Anybody have other inexpensive options?

 

[AstroSonic]

The usual upgrade driver for that cab was a JBL or Altec, both premium, costly drivers. Eminence Delta 15a or Beta 15a drivers are often used as replacements. Either would have considerably more power handling than the CTS's. A B25b cab with intact stock CTS drivers is relatively uncommon, and is worth passing on to someone who would prize the tone. If you have no use for such a cab you could sell it and apply the money to a new or used cab that meets your needs without the need to modify it.

 

[coreyfyfe]

I had delta 15s and beta 15s in my B25B cab. Preferred the betas personally, nice vintage tone and good power handling from the modern driver. Worked well with my SVT and V4.

 

[Fritzren]

Thanks for the replies folks. Some options to consider. Another thing I was considering as the SVT will just be a studio amp and I'm an awful kludge was buying this used eden 410 8 ohm cabinet 400w $150 and putting an 8 ohm load box in parallel with it. I'd lose 3db but who cares. I've had great luck using attenuators with tube guitar amps since in the case of the eight ohm shunt listed above the impedance the amp sees never goes over 8 ohms at any frequency. If you look at the impedance chart of the average driver the impedance goes up to 10 times the specified ohms at the resonance frequency and that's what kills an amp. See linked Google Image Result for https://www.eminence.com/img/curves/Beta_15A.png

But I'll probably buy the beta15as as I'm lazy

 

[Soulfinger]

The beta 15s sound fabulous in the B25b! I have one and love it.

 

[Fritzren]

I just read the SVT with attenuator thread and I'm afraid of opening a çan 'o worms. For the dummy load I would just use 4 100w 8 ohm resistors wired like an eight ohm cabinet mounted in a main service electrical panel. That would be 400w for the cabinet and 400w for the dummy load for a total is 800.

This thing will never go over 110 db in the studio so it won't ever work too hard. I've found with using a strictly resistive attenuator to dump 3-6 db does not change the tone with a guitar amp and increases the life of the tubes with the more stable impedance. I am just using the attenuator to get the master volume up to two so it isn't so sensitive.

 

[Fritzren]

The beta 15s sound fabulous in the B25b! I have one and love it.

That's the way I'm going

 

[JimmyM]

The usual upgrade driver for that cab was a JBL or Altec, both premium, costly drivers. Eminence Delta 15a or Beta 15a drivers are often used as replacements.

Yep. I've got Deltas in my B-15 cabs and they sing. They sound just like the early B-15 CTS's to me but handle a butt-ton more power. Never tried the Betas but I imagine they're fairly close by specs.

 

[Fritzren]

Question for b25b owners: Do I need to replace or remove the impedance switch in the cabinet for the extra power?

 

[BogeyBass]

Depends on what your doing and what amp. Delta 15 works, also available in 16ohm so you could also make a 8ohm 2x15 if needed or the typical 4ohm 2x15

For significant increase in power handling the cast frame Kappa pro 15 or Delta Pro 15. the kappa pro offers alot more highend and midrange detail than the well known CB158. likewise the Delta Pro has very very high sensitivity and very nice highend.

Similar driver with same power handling is the Neo Deltalite II 2515. this is a more affordable neo driver. definitely a higher budget and great performer. Still alot more affordable than the ever so common kappalite 3015

the low cost combo speakers mentioned are yes affordable. but efficiency isnt stated and power handling is not good at all. extra 20 or so for a Delta 15 is better. there is many many cheapo drivers from pyle , prv etc etc that perform slightly better pretty much the same as those combo speakers. expect 94 to 96 dB and no highend.

but heck the garbage speakers found in the fender rumble series keep alot of people happy. and again same thing. very very low sensitivity, no detail and fart out

 

[Fritzren]

Thanks for the reply, the question I'm asking though is if the stock 4/16 ohm impedance switch can handle the extra power for a SVT. Or should I tear it out and rewire the cabinet from scratch?

 

[JimmyM]

Thanks for the reply, the question I'm asking though is if the stock 4/16 ohm impedance switch can handle the extra power for a SVT. Or should I tear it out and rewire the cabinet from scratch?

All that switch does is change the wiring from series (16 ohm) to parallel (4 ohm), so if it ain't broke, don't fix it.

 

[coreyfyfe]

Thanks for the reply, the question I'm asking though is if the stock 4/16 ohm impedance switch can handle the extra power for a SVT. Or should I tear it out and rewire the cabinet from scratch?

The switch should be okay, they were added to these cabs so they could be sold/paired with SVTs and V4Bs and not jut the B25B heads. The first year or so of production did not include the series/parallel switch, the cabs were 16 ohms only. In the wiki link up top you can find some old ampeg catalogs (probably under wiki > portaflex wiki > product literature) where they show these pairings as options. When I had my B25B cab I just bypassed the switch since at the time I didn’t have a 16 ohm head. It wasn’t until years later I actually got a B25B amp (at which point I had already sold the cab).

 

[BogeyBass]

in good working condition it should be fine. you dont have to use it.
Im one those guys that will atleast keep the parts or even leave things on vintage cabinets.

just like the original cts speakers, nothing special really, have value to collector of some sort and should be respected.

its funny to me, back in the 90s just old turd speakers you could get for 20 bucks lol. i had fun time blowing up alot cts speakers with pretty minimal powered 100 to 200 tube or solid states. heck my 90 watt traynor creamed a few of those things

 

[Fritzren]

in good working condition it should be fine. you dont have to use it.
Im one those guys that will atleast keep the parts or even leave things on vintage cabinets.

just like the original cts speakers, nothing special really, have value to collector of some sort and should be respected.

its funny to me, back in the 90s just old turd speakers you could get for 20 bucks lol. i had fun time blowing up alot cts speakers with pretty minimal powered 100 to 200 tube or solid states. heck my 90 watt traynor creamed a few of those things

Thanks, I'll leave it stock. We don't get that loud in the studio. 400 W would be 40 v @ 10A with a 4 ohm cabinet with 5A going to each speaker. The wiring appears to be about 16 gauge, good for 15A, so I'll leave it. I'll stash away the CTS speakers for vintage sake.

Thanks for all the help folks

 

[AstroSonic]

Thanks, I'll leave it stock. We don't get that loud in the studio. 400 W would be 40 v @ 10A with a 4 ohm cabinet with 5A going to each speaker. The wiring appears to be about 16 gauge, good for 15A, so I'll leave it. I'll stash away the CTS speakers for vintage sake.

Thanks for all the help folks

You should look at the connectors and exposed wire for signs of corrosion - typically a shade of pale yellow or green that looks chalky. If present, the tone and power delivered to the drivers can be degraded. Rewiring is inexpensive and easy. Just watch the polarity (so the drivers are in-phase).

 

[BogeyBass]

Thanks, I'll leave it stock. We don't get that loud in the studio. 400 W would be 40 v @ 10A with a 4 ohm cabinet with 5A going to each speaker. The wiring appears to be about 16 gauge, good for 15A, so I'll leave it. I'll stash away the CTS speakers for vintage sake.

Thanks for all the help folks

oh yeah, switch is fine if in good working order. main issue is current. weakest link would actually be the 1/4 inch jacks. but that is pretty normal and non issue. this is a Delta pair. thermally they could probably do 400 watts. youll figure out where they get distortion by ear. which will be significantly lower than 400 watts. Vpp would be closer to 115 volts, but yes 40 volts RMS for 400 watts.

thermal rating for delta is pretty high below 100 hz single delta do about 65 to 95 watts before distortion, above 100hz about 120 to 150 watts. basically 2x15 pair is good for 160 to 200 watts of bass. sensitivity is high though so it will get very very loud in low volume setting no problem for you. so yes really clean 200 watts from a 400 watt bass amp

I had some older traynor sealed 2x15s and loaded them with gamma 15a speaker similar in performance to the deltas and betas. there not exactly the same but basically same performance as the Deltas far as power before distortion

they are not crushing power houses, but i had plenty of fun and had way way more overhead than the marsland speakers that came in those traynors, not very far from the CTS

as mentioned way way better idea than those combo speakers. they are rather muddy and efficiency is poor

 

[Fritzren]

Got the SVT hooked up to test today. Of course keeping it low to not fry the old CTS speakers. My god the clarity. Its like someone switched a cheap focusrite computer interface with a studer 2 inch analog, or that's the best analogy I can think of

 

[Oren Hudson]

My 2 cents. When I did my B25B about ten years ago, I had some JBL D140F's in the stash and used them in it. As attested by others, they are amazing in there.