Speaker Replacement

[billfitzmaurice]

I've now fixed the problem, as Bill guessed it was the highpass capacitor to the 10 that had gone. All working lovely now, just got to give it a test now for a 35 min loud run at a gig.
In the end I took out the tweeter crossover so now its just wired with a 15" and 10" in parallel with a 100uF capacitor in series with the positive leg of the 10" speaker. Please feel free to post any improvements I may be able to make over this.

Add this in series with the fifteen:
[Invalid or Expired Link Removed]

It will lowpass the fifteen at 200 Hz with a gradual 1st order slope, which is best in this application. The change will be only moderately audible, but it will raise the impedance in the mids to 8 ohms, greatly reducing stress on the amp.

 

[Skyvalley]

The sage continues on this, I've now managed to blow the replacement 100uF capacitor on the 10". It lasted 1 gig and half a practice. Replaced it and all OK but I've noticed that since I replaced the original 15" with the 3015LF the whole cab seems less "loud" and the 10" seems to be doing quite a lot of the work. The bass is very good coming out of the 3015LF but I have to turn it up loud in a band situation and then the 10" is being driven pretty hard it seems compared to the 15".

I did send a mail to Celestion to see if they had a datasheet for the 10" Celestion BG10 T 150 (8 ohm) driver but they didn't and could only send me the spec for a TF1020 which they tell me is "very similar". Sensitivity is 98 for the TF1020.

Not gone anywhere yet with the inductor.

If someone could try and point me in the right direction on how the 10" and 15" might be working together.

Thanks
Mark

 

[greenboy]

You really should provide photos of wiring and highpass. And make sure you are using at LEAST a 250V cap, non-polarized, metallized polypropylene or polyester. Also likely the 10" driver should just be crossed higher.

I'm not real keen on designs that highpass only though. They seem to be fraught with problems.

A better tuning for the 3015LF for most people would be more like 46 Hz, but if they like more midbass hump you can tune it even higher unless you are dumping scads of LF boost into it. What is your bass's lowest string?

 

[Skyvalley]

The old setup was a Delta 15-A 8 Ohm with the Celestion BG10 T 150 8 ohm wired in parallel. There was a highpass/crossover pcb on the 10" pair which included a 100uF 100v non-polarising capacitor in series on the 10". The crossover was switched in from the back and was only used to optionally split off the high frequency for use on the tweeter.

Current setup i've replaced the Delta 15-A with the 3015LF wired in parallel with the same Celestion 10" 8 Ohm. I've put a replacement 100uF 100V non-polarising in series on the positive leg of the 10" , probably a cheaper part than the original I imagine.

 

[Skyvalley]

in answer to you other question my lowest sting is normally a low E tuned down to C Sharp - 34.65Hz

 

[greenboy]

Ah. I'm at Bb/Ab Hipshot on one bass right now, the other at A/G. I was using low F# for a long time, but on 34 or 35" scale it seems like even with a good 3015LF the strings themselves are the issue until you go to longer scale lengths - for my tastes anyway.

 

[billfitzmaurice]

The old setup was a Delta 15-A 8 Ohm with the Celestion BG10 T 150 8 ohm wired in parallel. There was a highpass/crossover pcb on the 10" pair which included a 100uF 100v non-polarising capacitor in series on the 10". The crossover was switched in from the back and was only used to optionally split off the high frequency for use on the tweeter.

Current setup i've replaced the Delta 15-A with the 3015LF wired in parallel with the same Celestion 10" 8 Ohm. I've put a replacement 100uF 100V non-polarising in series on the positive leg of the 10" , probably a cheaper part than the original I imagine.

Everything they could do wrong, they did, from not having an inductor on the fifteen to using a 100v electrolytic cap. Greenboy and I have told you the right way. As for the 3015LF not being as loud, that has to do with the differences in the drivers. The Delta 15 will seem louder, but it's all in the midbass, with no real bottom end. The 3015LF will take eight times the power that the Delta 15 will in the low end, and will deliver real bass instead of midbass boom, but it needs a powerful amp driving it to get what it's capable of giving. The 3500 is OK, but won't get out of a 3015LF what it's fully capable of. For now if you want the 3015LF to sound like the Delta 15 did boost the EQ at 125Hz.

 

[greenboy]

I don't think that head takes kindly to difficult loads either, at least my limited experience with it gives me that impression.

 

[billfitzmaurice]

I don't think that head takes kindly to difficult loads either, at least my limited experience with it gives me that impression.

It doesn't. Even with an 8 ohm load I could easily get mine to go to protect mode, all it took was a hard strummed chord, and with the sensitivity of my cabs I wasn't exactly pushing the power envelope.

 

[Skyvalley]

Thanks Bill, Greenboy, for your help on this one. I'll try the boost of the 125Hz, I was reluctant to boost anything low on the graphic due to past problems with the Delta 15-A but as you say, if the 3015LF can handle 8x more then I should not have a problem.

Greenboy, is it right I can use non-polarized or metallized polypropylene or polyester capapcitors for the highpass? Having trouble finding a non-polarized 100uF that is rated any higher than 100V here in the UK.

Bill, regarding that inductor I would have bought it from Parts Express but they have a $40 minimum order and also a very expensive shipping to the UK ($33). So the $18 part will cost me $73 to get it to my house! I'll keep looking around the UK sites to try and find one or maybe do lots of reading and wind my own inductor.

 

[greenboy]

There should be equivalent ratings and values available from closer sources. But if the 10 is working too hard and you want to do some boosting at 125Hz or around there, I'd consider moving to around 80-82uF, something like this:

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[billfitzmaurice]

Bill, regarding that inductor I would have bought it from Parts Express but they have a $40 minimum order and also a very expensive shipping to the UK ($33). So the $18 part will cost me $73 to get it to my house! I'll keep looking around the UK sites to try and find one or maybe do lots of reading and wind my own inductor.

Sift through this, there should be a reference to crossover parts suppliers. Considering hi-fi was more or less invented in the UK it's a dismal situation when one can't find a decent parts supplier there.
http://billfitzmaurice.info/forum/viewtopic.php?f=14&t=4140

 

[Passinwind]

Having trouble finding a non-polarized 100uF that is rated any higher than 100V here in the UK.

Then use two 50uF or three 33uF caps in parallel.

 

[greenboy]

Which then allows one to get away with 100v rated parts.

EDIT: Wrong. Disregard.

 

[billfitzmaurice]

Which then allows one to get away with 100v rated parts.

Not when parallel wired.

 

[greenboy]

Oops, my brainfart. Indeed, true.

 

[greenboy]

Could contact http://www.barefacedbass.com/ and ask where Alex is getting crossover components.

 

[Skyvalley]

Thanks Bill, Looks like www.audio-components.co.uk can sort me out with both the higher voltage rated cap and the inductor.

 

[billfitzmaurice]

Thanks Bill, Looks like www.audio-components.co.uk can sort me out with both the higher voltage rated cap and the inductor.

Use the PCore coil, AC-JA03-1411.

 

[Rick Auricchio]

You should be able to series-wire two caps (each double the capacitance) to get double voltage.

E.G. a pair of 200uF/100v caps in series would get you 100uF/200v total.