PERSPEX QUASAR ver 2.0 prototype build

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IslandPink
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#136 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by IslandPink »

That's a VERY small picture, Ray !
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Ray P
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#137 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by Ray P »

Sorry Mark et al, I've tried again...
Aurel Bryan FR units.jpg
There doesn't seem to be a website. They seem to be handmade by a small outfit in Indonesia and most of the material I found apears to be on Facebook, which I decline to use. I understand that you can get a proper spec sheet (instead of my screengrab) from the Facebook pages.

If you Google 'Aurel Bryan loudspeakers' you'll find images etc. and some references on DIY Audio - comments about them are positive. Here's one link, from where I grabbed the spec sheet;

https://www.diyaudio.com/forums/multi-w ... ost5215426
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#138 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by Ray P »

I think the answer to this question is 'No' but it would be good to confirm.

Assuming the use of a line level passive or active crossover and therefore separate amplifiers, is there any reason why one wouldn't mix a 15ohm Lowther PM6A with an 8ohm bass unit?

Cheers
Last edited by Ray P on Sun Apr 04, 2021 10:30 am, edited 1 time in total.
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Nick
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#139 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by Nick »

No.
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#140 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by Ray P »

Cheers Nick
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#141 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by Scottmoose »

Ray P wrote: Sun Apr 04, 2021 8:53 am I think the answer to this question is 'No' but it would be good to confirm.

Assuming the use of a line level passive or active crossover and therefore separate amplifiers, is there any reason why one wouldn't mix a 15ohm Lowther PM6A with an 8ohm bass unit?
There's no reason why you couldn't do that with a passive speaker level filter either for that matter. The vast majority of multiway loudspeakers do not use drive units of the same nominal impedance, which is itself an emphemera given that conventional moving coil drive units have varying impedances anyway, at resonance[s] and with coil impedance. I could point out dozens of regular cone & dome designs where the HF impedance trundles merrily over 12ohms & points north. However, concerned that the basic mid-tweeter impedance would be too high for a given amplifier to be happy? Fine: shunt it with a suitably rated resistor or a resistor grid. It'll damp the Fs impedance peak a bit too. Then design your filter with the actual impedance load from driver + resistive damping shunt. Job-jibbed.
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#142 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by Ray P »

Yes, it's obvious when you put it like that Scott. :oops: Thanks though.

The reason for the question was actually more related to amplifier choice; if I follow Nick's lead with the PM6A units, the 15ohm silver coil version, which has a very similar FQ to the 8ohm unit, would probably allow me to use my flea-power SE-OTL amps for reasonable volume in a domestic environment - would be good to try that.

Given the LF roll-off of the Lowther units do I even need a crossover filter or could it just be run 'open'?

Hmmm...
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#143 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by chris661 »

Best to run with a filter, and preferably before the amplifier if power is limited.
Even if there's an acoustic rolloff, the cone will still be flapping around in response to LF signals - better to leave that job to the bass driver(s).

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#144 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by Ray P »

Yep, I expect to have to bandwidth limit the signal to the full-range unit, just concerned about insertion losses but with an active preamp I should be able to compensate for that and still use the flea-power amps.
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#145 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by IslandPink »

If it's a flea-power amp, I'm assuming a valve amp, in which case you ought to have a location ( coupling cap ) where you can just alter values to give you a high-pass , rather than adding a filter at the front ?
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#146 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by JamesD »

Just a quick note that if building a passive series filter Quasar then the Ze & Re does need to be taken into account ..

ciao

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#147 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by Ray P »

IslandPink wrote: Mon Apr 05, 2021 12:59 pm If it's a flea-power amp, I'm assuming a valve amp, in which case you ought to have a location ( coupling cap ) where you can just alter values to give you a high-pass , rather than adding a filter at the front ?
Yeah, I know Mark, but then you have the dilemma of restricting how you can use the amplifier - compromises, compromises...

I have been contemplating one of the Pass designed active crossovers available from the DIY Audio store but this has picqued my interest too;

https://www.diyaudio.com/forums/pass-la ... sover.html
Last edited by Ray P on Mon Apr 05, 2021 7:20 pm, edited 1 time in total.
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#148 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by Ray P »

JamesD wrote: Mon Apr 05, 2021 5:17 pm Just a quick note that if building a passive series filter Quasar then the Ze & Re does need to be taken into account ..

ciao

James
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#149 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by IslandPink »

Ray P wrote: Mon Apr 05, 2021 7:13 pm Yeah, I know Mark, but then you have the dilemma of restricting how you can use the amplifier - compromises, compromises...
OK , well, it might be as simple as changing a grid-leak resistor. In which case.... could you provide two resistors, with a quality switch to choose between full-range and high-pass operation ?
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#150 Re: PERSPEX QUASAR ver 2.0 prototype build

Post by Ray P »

Thanks Mark, food for thought. Another option, given that I have both the 13E1 and 6C33C flea-power SE-OTLs, might be to just use them for different purposes.
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