Replacement speaker for Roland Studio Bass 100

['brations]

I've had a Roland SB100 (100 watt 1x15 combo) for around 20 years. I'm only an occasional bass player these days – I mainly play guitar – and made the mistake of loaning out the amp a while ago when I wasn't playing much at all. When I got it back, it was cooked (petrified R&P C1238B speaker).

When I first got it back in the 90s, it was fantastic. Admittedly, I've never played through any high end Ampeg or equivalent rigs with more sophisticated tone, but to my teenage ears, it sounded great and was plenty loud enough to compete with two guitars and drums on volume 3–4. I played an Ibanez RB850 with fairly hot pickups through it at the time.

I took it to a local music shop to get it repaired. At the time I wasn't fussed about paying a lot of money repairing it, but just wanted it back in good enough condition. I've recently started playing with some friends and put it back through its paces and the sound could not be more underwhelming.

The speaker that was put in was a Celestion Truvox 1525 – the tech said that is a decent replacement. It's anything but and after looking up that model, it turns out its a PA speaker, not a purpose built bass amp speaker.Celestion TF 1525 PA Speaker: Woofer 8 ohm | Musician's Friend

I'm keen to resurrect the amp to its former glory. I don't know a lot about amp specs, but this is my best guess at something that would be on par or better than the C1238B that came out – [Invalid or Expired Link Removed]

The price seems reasonable and I wouldn't probably want to pay much more than that. Any confirmations that this is a good option? The RMS rating and impedence are right (I think), but are there any other specifications I need to keep any eye out for when assessing whether this is a good fit for the amp?

Thanks in advance for all help and feedback.

 

[Arjank]

There's nothing wrong to use the Celestion Truvox TF1525 as a bassguitar speaker except for the fact that it's not designed for ported cabinets (correct me if I'm wrong but the Roland combo is ported, right?).
Although we don't know the port tuning and enclosure volume of the combo the Emi CB15 is definitely better suited for the task then the Celestion.
The CB15 has pretty "flexible" Thiele-Small parameters and will be a good replacement.

If you can provide the inner dimensions(approx) of the cabinet and the dimensions of the port (WxHxD) then I can check if the CB15 is the best choice.

 

['brations]

Thanks for the reply Arjank. Yes, it's ported http://i.ebayimg.com/00/s/MTYwMFgxMjAw/z/9~kAAOSwd0BVxrtt/$_75.JPG

I can't measure it at the moment. Do you need me to calculate the capacity (in Litres) of the space behind where the speaker is mounted?

 

[Arjank]

Thanks for the reply Arjank. Yes, it's ported http://i.ebayimg.com/00/s/MTYwMFgxMjAw/z/9~kAAOSwd0BVxrtt/$_75.JPG

I can't measure it at the moment. Do you need me to calculate the capacity (in Litres) of the space behind where the speaker is mounted?

Yes.
Also, the port looks very large, it may be the case that the port area is smaller at the point where the port enters the inner space of the cabinet. So check as much dimensions as possible.

 

['brations]

Yes.
Also, the port looks very large, it may be the case that the port area is smaller at the point where the port enters the inner space of the cabinet. So check as much dimensions as possible.

Hi Arjank,
I've calculated that the enclosure for the speaker is around 103L (60cm (w) x 52cm (h) x 33cm (d)). The port is roughly 60cm (w) x 20cm (h) x 30cm/40cm (d depending on whether you measure from the bottom or top of the port – it angles towards the front at about 45º). The port opening at the back is 5cm deep.

Hopefully this is enough information to inform your recommendation.

cheers.

 

[Arjank]

Hi Arjank,
I've calculated that the enclosure for the speaker is around 103L (60cm (w) x 52cm (h) x 33cm (d)). The port is roughly 60cm (w) x 20cm (h) x 30cm/40cm (d depending on whether you measure from the bottom or top of the port – it angles towards the front at about 45º). The port opening at the back is 5cm deep.

Hopefully this is enough information to inform your recommendation.

cheers.

That's the info I need, the port is kind of a horn-reflex system and I can simulate that in AJhorn

 

['brations]

That's the info I need, the port is kind of a horn-reflex system and I can simulate that in AJhorn

Great. I'm a little out of my depth with the technology/terminology at this point, but I'll look forward to your response.

Cheers

 

[Arjank]

If I understand you correctly the port has a conical shape? and it's 40cm long(deep) in total?
Something like this?

 

['brations]

If I understand you correctly the port has a conical shape? and it's 40cm long(deep) in total?
Something like this?

View attachment 669457

Arjank,

It's more like this. I've included another couple of reference shots.

thanks.

[Invalid or Expired Link Removed]

 

[Arjank]

Ok, it's indeed a sort of horn-reflex system, the average path length is 45cm, port throat area is 300cm2, port mouth area 1200cm2.
Simulations in AJhorn show a tuning frequency of approx 54hz.

Below the simulation with the CB15, as you can see there's a bump, but that's what you can expect with a relative high tuning.
The 2nd simulation is with the Emi Kappa pro 15A, this driver has a smoother response in the enclosure.
The kappa has a smaller xmax but the combo is only 100watts, so this isn't a problem. The Kappa also has a nice extended midrange without a 2khz bump which is a good thing IMO. Some others like a bump around that frequency band, but you can always dial that in with the EQ of the SB 100.

I've simulated almost all the other options available from Eminence but the Kappa Pro 15A gives the best results. IMO this is the driver you need to get that combo in shape again.

 

['brations]

This is brilliant – thank you so much.

I'll report back.

 

[parker 71]

Any further info?

 

['brations]

Hey Parker71,

Sorry for not making good on my promise of feedback.

Ultimately, the Eminence speaker has made a dramatic improvement and the SB100 can hold its own against my Fender Twin-Amp and my friend's AC30 going at a decent clip. I'm going back a long way, but it still doesn't feel as tight or powerful as the original speaker did. Admittedly, in those days it was competing with less powerful guitar amps and I'm playing a Fender Jazz through it these days, not the Ibanez: not comparing apples with apples.

I probably need to get somebody to have a look at the head too and make sure all's well there, but I mainly play guitar these days and my guitar gear gets a greater share of my attention, and budget.

Hope that's helpful. Do you own an SB100?

 

[parker 71]

Well, SCB100, little different - more like modern cubes but without modeling. And also in need for repair, treble and one of middles are broken.
Otherwise, it's working and cool vintage sounding amp, good for rehearsal and maybe some smaller gigs..

 

[T-Minus]

I've just bought an SB-100 on eBay and it's arrived with a damaged speaker - apparently the magnet has moved and according to the repairman is 'stuffed'. Pretty disappointed about that...
I've tried the head through a 2x10 Ampeg cab and it sounds GREAT. So can't wait to get the Eminence Kappa Pro 15A installed in the main unit (although from the US the postage/import tax situation is almost intolerable thesedays).
So glad that this thread is here as there's really not too much about the ol' SB-100 online. Thanks!

 

[Bass V]

anybody else happy with their SB 100?