OB project, Jame's Quasars copy

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IslandPink
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#16 Re: OB project, Jame's Quasars copy

Post by IslandPink »

thomas wrote: Wed Jan 10, 2018 10:15 pm ..., but is it worth buying a handful of cheap(ish) inductors and trying adding them incrementally in series and only splashing out on an air core when I'm happy with the set up?!
I'm not sure about buying a handful, as you would exceed the cost of one E-I inductor at 6.8 to 8.2mH pretty quickly, but if you have stuff to hand, by all means. The DCR or the inductors might add up, but as this feeds the bass driver, you can take this DCR off the attenuating resistor.
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#17 Re: OB project, Jame's Quasars copy

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My mistake I misread the value in the diag.
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#18 Re: OB project, Jame's Quasars copy

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I am sure James speakers have a big ei choke not a air core. Won't increased dcr put more lf across the upper driver?
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#19 Re: OB project, Jame's Quasars copy

Post by IslandPink »

James's Quasars use a humungous 12mH air-core with 2mm or 2.5mm wire. I have helped him move them from the car into Owston on a couple of occasions :D
More DCR is like series resistance into the bass driver.
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#20 Re: OB project, Jame's Quasars copy

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Ok but won't more DCR mean that the inductor is less able to shunt low frequencies past the full range driver.
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#21 Re: OB project, Jame's Quasars copy

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My air cores were about £120 each IIRC :oops:
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#22 Re: OB project, Jame's Quasars copy

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Nick wrote: Wed Jan 10, 2018 4:38 pm Sorry to depress you, but the "kids" have never head of the Fast Show :-(
I know. It's over 20 years old now. Arse!
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#23 Re: OB project, Jame's Quasars copy

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Nick wrote: Thu Jan 11, 2018 12:29 am Ok but won't more DCR mean that the inductor is less able to shunt low frequencies past the full range driver.
Yes - and in this case it's not a big deal, as the bass driver needs attenuating slightly anyway. The LP slope should be in the same place , just a bit of amplitude attenuation.
... edit : I see what you mean, I suspected there was more than one reason why James went for such thick wire and low DCR.
Anyway, compared to what Thomas has now, having the HP slope on the full-range driver, whatever the DCR, should be a significant improvement.
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#24 Re: OB project, Jame's Quasars copy

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IslandPink wrote: Thu Jan 11, 2018 9:57 am
Nick wrote: Thu Jan 11, 2018 12:29 am Ok but won't more DCR mean that the inductor is less able to shunt low frequencies past the full range driver.
Yes - and in this case it's not a big deal, as the bass driver needs attenuating slightly anyway. The LP slope should be in the same place , just a bit of amplitude attenuation.
... edit : I see what you mean, I suspected there was more than one reason why James went for such thick wire and low DCR.
Anyway, compared to what Thomas has now, having the HP slope on the full-range driver, whatever the DCR, should be a significant improvement.
Yes, the DCR will add a shelf to the 6dB slope.
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#25 Re: OB project, Jame's Quasars copy

Post by thomas »

Well I had the speakers cranked up louder tonight and I don't know if its because the drive units are loosening up or if it's the power of suggestion but the bass did seem a little err relentless.....

I might have to unleash the EX3s.....

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#26 Re: OB project, Jame's Quasars copy

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thomas wrote: Thu Jan 11, 2018 10:32 pm
I might have to unleash the EX3s.....
:shock:

Best criss-cross safety tape across all the windows first Thomas just in case they blow with that amount of Sidcups' finest screecher energy being unleashed :)

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#27 Re: OB project, Jame's Quasars copy

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thomas wrote: Thu Jan 11, 2018 10:32 pm Well I had the speakers cranked up louder tonight and I don't know if its because the drive units are loosening up or if it's the power of suggestion but the bass did seem a little err relentless.....

I might have to unleash the EX3s.....

All good fun
But without the inductor, the PM6C is being asked to do bass as well, so I would expect problems whatever driver you use.
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#28 Re: OB project, Jame's Quasars copy

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Correct, but actually it's got more to do with the cap value, where the full-rangers come up. The inductor predominantly rolls off the bass driver. Without the inductor you'll get plenty of crud from the Eminence coming through in the upper mids and treble to add to the screeching :shock:
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#29 Re: OB project, Jame's Quasars copy

Post by simon »

What Nick and Mark said, which was my point earlier. But also, I find the louder the volume the more the volume relatively from the bass driver. This was most notable when I took the Quasars to Owston a couple of times ago. Played in the barn of a room (at much higher volume) compared to a bedroom at home the bass completely overwhelmed the sound.

I "fixed" it by using half an Lpad as the series resistor so I can vary the amount of bass to suit now. And by having more bass at lower levels I found I don't push the volume control as much. Which has to be good. But I can easily tweak it if I do want to turn up the volume.
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#30 Re: OB project, Jame's Quasars copy

Post by Nick »

The more I think of series xovers the more I realise I don’t understand them, but with only the cap there I don’t think any of the simple explanations you can make with a conventional xover can be made. I think without the inductor its just not valid in any way. Mark knows more about this stuff, but I think you would be better to get (or make) a inductor instead of trying different drivers.

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