Speaker Replacement

[Skyvalley]

Hi

In the last 6 months I've managed to ruin 2 15" Eminence Delta 15A drivers in my Cab. Before I spend any more cash on a new driver I need to confirm my thoughts regarding what was blowing the coils in the speakers.

I play a 350 watt Hartke HA3500 head into a Ashdown ABM 1510HX (1x 15" and 1x 10" + Tweeter) rated at 4 Ohm 400W. The head pumps out 350watts at 4 Ohm.

I've taken each speaker cone apart to find a charred blackened coil in each. After reading quite a few threads here my main theory for the damage caused is by too much low frequency at a high volume. The bass volume issue I think was caused by me boosting the 30Hz EQ by about "+5" on the graphic, I don't turn the main volume anywhere above 4-5 as that is plenty enough overall volume. Another consideration is the tuning of my bass which is tuned half a step down, then on some songs the low E is tuned down a further whole step down making the lowest frequency 34.65Hz (C Sharp). The style of playing doesn't help either, a lot of the songs the band plays involve constant repetitive picking of the low E. I also use a Tech 21 VT Bass pedal which gives the sound a whole lot more of everything.

My amp manual recommends a cabinet of 600 watts at 4 Ohms although I read here that cab ratings can lower than recommended as long as the volume is kept at a sensible level? This got me thinking that I should upgrade the driver in the box for a 600W Eminence Kappa Pro 15LF-2 and then retune the cab to 35Hz using the figures from WinISD. This new lower tuned cab would be a better match my low tuned bass. Is this a useful idea?

Only other question running around my head is one my speaker supplier suggested that I check my amps output for DC. I don't really know how to test for this correctly. I'm always reluctant to switch the amp on without a speaker load on it.

Thanks for you time.
Mark

 

[rpsands]

A 350 watt amp can typically peak well over 350 watts (often double or more). 600w is a good idea.

Your amp putting out DC is so unlikely as to be a laughable suggestion from what I can gather - kind of a mythological idea almost. The 3500 is fine to turn on without speakers, unless the manual says otherwise - only tube power amps are a concern there in most cases.

I'd suggest:
1) Do not boost at 30hz - boost at 80hz-ish, for that kick in the chest from a low E (or 60hz for a little lower, not sure where your sliders are. No one can really hear 30hz well and your speakers can't produce it at a meaningful volume anyway

2) You need to measure the internal volume of the enclosure and measure the ports, and know what the crossover design of your cabinet is, to pick a new speaker. You also should know the specs of your 1x10. Otherwise you could easily get undesirable interactions by changing speakers.

 

[billfitzmaurice]

Hi

In the last 6 months I've managed to ruin 2 15" Eminence Delta 15A drivers in my Cab.

Delta 15s are very poorly suited for electric bass, they lack excursion capability and require a huge cab to get any bottom end from them. Anything over 75 watts into a D15 will give no additional low end output, only additional heat in the motor, and that's why you cooked them.

My amp manual recommends a cabinet of 600 watts

Moot. What counts is frequency response, sensitivity and excursion, and the Delta 15 sucks in all three areas.

This got me thinking that I should upgrade the driver in the box for a 600W Eminence Kappa Pro 15LF-2 and then retune the cab to 35Hz using the figures from WinISD.

Obsolete. Use the Kappalite 3015LF.

 

[Skyvalley]

Thanks Bill, I had a look at the spec for the 3015LF and it looks great, my cabinet volume (122 litre) looks good for the unit.

Just wondering if I should tune it once I get the new driver? Measuring the current port size and plugging in all the values into WinISD it does does not look like the ideal size port to me when using the Delta 15A, I'm guessing Ashdown went for greater loudness/volume over a low frequency in the original design, could I improve on this with the new driver and then a tune? or maybe just put the driver in and play a band practice with it to see how it sounds?

 

[billfitzmaurice]

I'm guessing Ashdown went for greater loudness/volume over a low frequency in the original design, could I improve on this with the new driver and then a tune? or maybe just put the driver in and play a band practice with it to see how it sounds?

Not knowing what Ashdown used for a driver or how the cab is tuned I can't say what their intent might have been. At 112L I'd tune a 3015LF to 40 Hz.

 

[rpsands]

Thanks Bill, I had a look at the spec for the 3015LF and it looks great, my cabinet volume (112 litre) looks good for the unit.

Just wondering if I should tune it once I get the new driver? Measuring the current port size and plugging in all the values into WinISD it does does not look like the ideal size port to me when using the Delta 15A, I'm guessing Ashdown went for greater loudness/volume over a low frequency in the original design, could I improve on this with the new driver and then a tune? or maybe just put the driver in and play a band practice with it to see how it sounds?

Are you sure that the cabinet is 112 liters? Taking into account displacement of other drivers, the 10" enclosure if it has one, and so on? Just be sure otherwise your tuning might wind up off.

 

[Skyvalley]

I made sure the 10" internal enclosure volume was subtracted from the full volume measurement I made. Not bothered with the 15" driver displacement yet, I realise there will be a difference between the Delta 15A and the 3015LF due to the reduced size of the magnet. Anywhere I can get displacement charts of different drivers?

 

[greenboy]

I use 208 ci for the driver. It's probably more than the driver actually takes, but it allows for other uncounted small things and has given tuning results within .5 Hz or so in a cab that of that size.

 

[JimmyM]

As a very satisfied Delta 15a user for about 2 years now, I have to agree with Bill. Turning up the bass and cranking the volume results in fart city. Instead of that, keep your bass knob down and cut everything else, then compensate with volume. But in moderation, not in-sanity.

 

[username1]

I have a hartke 3500 i use as a spare amp and i always have the 30hz slider pulled almost as low as it will go, the 60 hz mid way and do the bass boosting above that point. 30 hz frequency does nothing but suck power and make your amp muddy and keep you from projecting. You might want to put the compressor on a little also so it comes on only on the loudest low notes. Have never had a speaker problem.

 

[billfitzmaurice]

I have a hartke 3500 i use as a spare amp and i always have the 30hz slider pulled almost as low as it will go, the 60 hz mid way and do the bass boosting above that point. .

A Delta 15 in 112 liters is 15dB down at 30 Hz, 6dB down at 50 Hz, with a 3dB bump at 100 Hz, so it's not like he had much choice with the tone he wanted to get. When he gets the 3015LF in there he should be able to run the 30Hz flat, if not pulled down a bit. When I had a 3500 I always ran with the 30 Hz pulled about 3/4 of the way down.

 

[Skyvalley]

I've since re-measured my box and it's 122 L in volume not 112 L. This measurement is minus the 10" driver internal enclosure and the 15" driver displacement.

 

[Grooveman1961]

Check the eminence website for specific cab design recomendations. What you'll find in the design info is a warning about over powering the driver, and to limit power, in some cases to surprisingly low levels.

Edit: Yup, in bass applications the two designs eminence has limits power to 50 or 100 watts, depending on cab size and tuning.

 

[Skyvalley]

Hi, I finally got round and bought the 3015LF. Cut the port down to tune the frequency to 42Hz. All looking good except I noticed now the 10" driver in the cab is not moving, took it out and tested it with a multimeter and all looks good, also tested it on my hi-fi at low volume, no probs with the driver. Stuck my tester on the leads coming from the crossover turned the amp up a smidge and no AC current coming from the crossover. I do test what looks like a capacitor discharging.
If anyone could suggest any further tests please or also if it looks like a crossover issue then how to go about picking a new crossover please (I use the Blue Aran UK site so one from there if possible). Currently the cab is loaded with..

15" Eminence Kappalite 3015LF (8 ohm)
10" Celestion BG10 T 150 (8 ohm)
Tweeter (switchable from the back of the cab HIGH/LOW/OFF)

I'm happy to rewire it without the tweeter, I really don't see the point for the type of music I'm playing.

Thanks
Mark

 

[billfitzmaurice]

Hi, I finally got round and bought the 3015LF. Cut the port down to tune the frequency to 42Hz. All looking good except I noticed now the 10" driver in the cab is not moving, took it out and tested it with a multimeter and all looks good, also tested it on my hi-fi at low volume, no probs with the driver. Stuck my tester on the leads coming from the crossover turned the amp up a smidge and no AC current coming from the crossover. I do test what looks like a capacitor discharging.
If anyone could suggest any further tests please or also if it looks like a crossover issue then how to go about picking a new crossover please (I use the Blue Aran UK site so one from there if possible). Currently the cab is loaded with..

15" Eminence Kappalite 3015LF (8 ohm)
10" Celestion BG10 T 150 (8 ohm)
Tweeter (switchable from the back of the cab HIGH/LOW/OFF)

I'm happy to rewire it without the tweeter, I really don't see the point for the type of music I'm playing.

Thanks
Mark

If the ten is highpassed as it should be (but in 99% of multi driver bass cabs isn't :scowl you won't see the cone move. The way to know if it's working is to run signal through the cab at low level with the woofer disconnected.

 

[Skyvalley]

If the ten is highpassed as it should be (but in 99% of multi driver bass cabs isn't :scowl you won't see the cone move. The way to know if it's working is to run signal through the cab at low level with the woofer disconnected.

Thanks Bill, I gave that a try with the 15" disconnected and there is nothing coming out of the 10". I messed with the tweeter switch on the back, the horn tweeter I could hear slightly but nothing from the 10".

 

[Skyvalley]

I had a look a the way it's wired and the 15" speaker is wired direct to the input. The crossover is also wired directly to the input and has two outputs going to the 10" and the Tweeter.

 

[billfitzmaurice]

I had a look a the way it's wired and the 15" speaker is wired direct to the input. The crossover is also wired directly to the input and has to outputs going to the 10" and the Tweeter.

That indicates probably the highpass capacitor to the ten is burned out. It's also the wrong way to do it, as the fifteen and ten are parallel wired above the highpass frequency to the ten. A proper crossover would have the fifteen lowpassed so that it and the ten don't fight each other in the mids.

 

[Skyvalley]

That indicates probably the highpass capacitor to the ten is burned out. It's also the wrong way to do it, as the fifteen and ten are parallel wired above the highpass frequency to the ten. A proper crossover would have the fifteen lowpassed so that it and the ten don't fight each other in the mids.

You've made me wonder now whether I should fix the current highpass/crossover or try and improve on the cab using an off the shelf crossover?

 

[Skyvalley]

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.