Ashdown Blue Line replacement

[Mick Bailey]

I've just been comparing drivers in WinISD to identify a replacement for the Ashdown speaker for a 330 Spyder combo. The Eminence Delta 15A is very close - slightly better response at 100hz and ever so slightly worse at 30Hz, near-identical curves for 100Hz onwards. I've used these before in Ashdown combos that seem to regularly destroy the Blue Line speakers, but not in a Spyder. Anyone got experience of this particular driver as a replacement in this situation? Standard-tuned 4 string bass straight into the amp.

Cost is a factor for my customer, hence looking at a lower-priced option.

[J M Fahey]

I would use that Eminence and call it a day.
You cant go wrong with it.
Hope it fits your customer's budget.

[km6xz]

Don't go by frequency response since it depended most on how it is coupled to the room and less the driver itself at 30hz. The 100hz higher sensitivity of the Eminence will translate to louder perceived low since the 2nd or 3rd harmonic will be what defines the note by how our brains infer fundamental when the harmonics present. Juan is right, go with a driver that will not come back.
Very few bass cabs offer effective matching between driver and the room with its extreme impedance mismatch between the high mass cone/VC/magnetic dampening versus the very low mass air so few depend on high SPL as the low fundamentals and rely on the nature of the brain to perceive strong bass. 30hz is the perfect storm of inefficiency where the ear sensitivity, driver efficiency, cab coupling efficiency, and room size all combine to make genuine 30hz perceived loudness pretty low, but adding a bit of second and third harmonic and the perception of the fundamental increases dramatically.

[Mick Bailey]

I installed the Eminence and it sounds just fine. As I didn't have the original driver in a working state, I couldn't A-B it anyhow but I'm pleased how it worked out - no shortage of bottom end at all (BTW, thanks for the explanation) and good mid clarity.

Interesting change to the wording on the speaker; the previous one I bought still said "Made in USA", but the new one is in a different box and says "Designed and assembled in USA".

The original driver is rated at 250W. I measured the output into a dummy load and the amp is putting out 235W just before it clips. When I spoke to the owner he says he "pushes it a bit". I noticed that at the point of clipping it then doesn't take much of a signal increase to push the amp well into square-wave territory. The peak voltage into the load doesn't increase, but the power flat out (if my Fluke true RMS meter is to be relied upon) is 360W. That's a big thermal input. OK, there are other factors to consider that would reduce this value into an actual speaker load, but perhaps this is why I see so many Blue Line speakers with O/C coils. That is, after they've first shorted and blown the speaker fuse and anything else.

[J M Fahey]

Interesting change to the wording on the speaker; the previous one I bought still said "Made in USA", but the new one is in a different box and says "Designed and assembled in USA".

I'm quite certain that they have parts (frames, coils, etc.) made in China and only final assembly is made in USA.
And probably in the future not even that

The original driver is rated at 250W. I measured the output into a dummy load and the amp is putting out 235W just before it clips. When I spoke to the owner he says he "pushes it a bit". I noticed that at the point of clipping it then doesn't take much of a signal increase to push the amp well into square-wave territory. The peak voltage into the load doesn't increase, but the power flat out (if my Fluke true RMS meter is to be relied upon) is 360W. That's a big thermal input. OK, there are other factors to consider that would reduce this value into an actual speaker load, but perhaps this is why I see so many Blue Line speakers with O/C coils. That is, after they've first shorted and blown the speaker fuse and anything else.

Well, that's certainly a tight spec.
Fine for a clean bass player but if he's into metal and/or tries to fight a Marshall stack or something, he'll blow it again.
Not your fault, of course.
Ashdown , together with many Amp designers which should know better do NOt fit limiters/compressors to their Bass amps, which is WRONG.
First, because SS bass distortion is not nice (to put it mildly) and second, because SS amps , not being current limited like Tube ones, *easily* put out gobs of squarewave power when clipped.
Tube amps on the contrary, both compress naturally and often sag.

I suggest you add some very simple Led/Ldr limiter and set it so the amp does not even reach clipping.

It will not sound less powerful and in fact will cut better through stage noise clutter.

[km6xz]

Yes, adding a compressor limiter to the rack will increase the perceived loudness while reducing the peak power. It will sound fatter and richer. Even some really cheap compressor/limiters can do wonders for wide DR signal sources. You never heard a vocal on a record or in concert that did not use compression to increase the average to peak ratio and transform the wide DR voice into a narrower dynamic range, to move the average level well above the noise floor of a concert, but reduce peak levels to within the DR of the sound system. Instead of buying a 2000 watt head and speakers to go with it, get him a Behringer $90 compressor/limiter, set it for 2:1 or 3:1, fast attack, slow release and set the limiter to 1/2 the peak power, and he will seem louder and fatter while ending the burned driver problem. Be sure to set it and then lock a cover over the face plate because the most messed with and least understood common device in a rack is the compressor.

[Mick Bailey]

Thanks for the advice on using a compressor/limiter. The amp already takes a rectified feed off the speaker output to provide DC to the output level meter circuit. Could be a ready-made reference signal for a straightforward satellite board to mount inside the amp.

[J M Fahey]

Yes, even the simplest Led/Ldr compressor will be fine.
You can borrow some of that audio rectified Dc voltage, buffer it with a TLo7x so it won't be affected, and drive a Led with 1K in series from its output.
Add some kind of trimmer so you can set it up, drive the amp a little beyond clipping (still recognizable sinewave with some flat tops) nd the raise sensitivity until flat tops disappear.
The attenuator itself is a 10 to 22K resistor in series with power amp input and LDR to ground.
2 stamp sized board (perfboard is fine) , hidden inside, out of reach from nervous fingers.

[km6xz]

An optical attenuator can work it is hard to get desired attack and decay times so it does not pump on bass notes. A relatively simple method would be to use one of the high performance Dynamics Engines from THAT Corp. They make the very common THAT 2252 RMS detector used in dozens of low to high priced compressors. But that one is being discontinued so to assure future access, it is best to design around their new Dynamic Engines like the 4301. They design notes have www.thatcorp.com/datashts/dn05.pdf that shows how to build a dual slope fully variable compressor with only one IC and some glue parts and pots. I got a few of the 4301's for free by asking for samples. I used one to build a 100db single range auto power meter (from .01microwatt to 1,000 watts)and a cool little compressor for my video work. My D800 Nikon DSLR has a AGC built in but this home made unit is more adjustable and lower distortion. The only down side is needing bipolar power, I get that from a single battery with a buck/boost regulator since the whole thing only pull 15ma. THAT makes a series of lower cost SMD chips that are single supply if you want to build using surface mount.

[km6xz]

To continue the thread. In the studio we seldom compressed the entire spectrum the same amount, it can lose vitality even as the power seems to increase. Compressors have something like an effects loop, called side chain, that allows the signal sampled by the RMS detector, to have a separate signal path than the signal being acted on by the gain cell. That side chain allowed up to insert an eq that could tailor the signal that the RMS detector received. For example if you wanted more compression on the bass but not the mid and highs of an instrument or vocal, dial in a low pass filter in the side chain so the bass would be compressed but the upper mids would not be. For speakers in a pa system, the real work is being done by the bottom octave amps and drivers and are at risk of over driving the drivers at any time. By adding an filter in the side chain of a guitar amp/speaker to limit bass cone excursion and peak power yet making it sound more powerful. The clean dynamic mids and highs are not a threat at all to the speaker because harmonics of any note are much weaker than the the fundamental and our ears are more sensitive so little power is used at, say,2khz, a couple watts, while the rest of the 98 watts is driving the cone crazy below the cut off frequency of the cabinet and driver.
My advice is to leave the upper harmonics lightly compressed but the bottom strongly compressed and no speaker will blow ever again, the highs will sound cleaner because of less wild cone excursion that creates Doppler shift for the hf riding on the deep excursions of the cone when hit hard with bottom.

With logical thinking, any amp and speaker can sound and perform much better than it does now, without resorting to phony magic dust and fairy tears. We got great sounds in the studio because a roadie did not touch the knobs and the artist just played. No fancy trick amps or effects boxes, in fact few would believe how stock the signal was. Thinking of how we perceive sound is the key, not just playing with it until we are happy. Stage can be the same but there, too many burnouts and wannabees got their hands on the sound before the audience did.

[Ted]

You know you can get Blue Lines direct from Ashdown? They are pretty cheap too - certainly cheaper than the Eminence - which is a way better speaker than most of the ones Ashdown put in their boxes.

[Mick Bailey]

The Blue Lines are a fairly common failure item - I have two more customers with failed speakers, so I don't want them coming back once they've been repaired. I actually pay less for Eminence at trade than the OEM speakers cost and the additional power handling makes them a safer bet (400W v 250W). If the Blue Lines are operated within their rating they're fine, but as soon as the amp starts clipping they thermally overloaded.

I have to say that Ashdown is one of the best companies to deal with for spares and support, and I don't want to criticise them unduly. It's just that when I carry out a repair I'm adopting responsibility for that equipment so I have to be as sure as I can that it will perform reliably.

[Ted]

I'd say speakers were about the most common failure item on Ashdowns (apart from those stupid wire-ended bulbs behind the meter)

I generally take the view that if it's for someone's personal amp, I'll suggest fitting Eminences, whereas if it's say a rehearsal room amp I'll just replace like with like.

[Jazz P Bass]

(apart from those stupid wire-ended bulbs behind the meter)

Oh, yeah.
Stupid Is As Stupid Does.