Dungeon Keeper

Dedicated to those large boxes at one end of the room
Daniel Quinn
Old Hand
Posts: 859
Joined: Thu Jan 05, 2017 9:19 am

#271 Re: Dungeon Keeper

Post by Daniel Quinn »

ffs not another spelling Nazi :mrgreen:
User avatar
andrew Ivimey
Social Sevices have been notified
Posts: 8307
Joined: Mon Jun 11, 2007 8:33 am
Location: Bedford

#272 Re: Dungeon Keeper

Post by andrew Ivimey »

Err.
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
User avatar
Scottmoose
Needs to get out more
Posts: 1802
Joined: Sat Sep 08, 2007 11:03 am
Contact:

#273 Re: Dungeon Keeper

Post by Scottmoose »

Nick wrote: Tue Apr 18, 2017 4:24 pm
The downsides of high order filters are potentially higher insertion losses than physically simpler designs, but these are typically less than you would get in terms of the production tolerances of most drive units.
"Downside" is a opinion, not a fact.
I'll respectfully beg to differ on that one Nick, although 'disadvantage' may have been the more correct term. The potential disadvantages I mention are real though.
And I dont TBH understand the second part as it looks to me like a conflict of units. "insertion losses" on one side, "production tolerances" on the other side.
Well, there's no industry standard for production tolerances on moving coil drivers, but the average is about +/-10% for components with QC for samples in a batch of completed drivers usually based on a mean Fzero (Fs to us) & the same overall tolerance. That's assuming they even bother, which is not always the case with very cheap units. Some of the quality brands run a lot tighter; Scan Speak, Seas, SB, Mark Audio etc. are usually in the 3% region. For high order filters you go into it knowing that you need to minimise insertion losses (other than those that are inherent to the filter), so you'll typically be using caps & inductors with very low resistance, and very close tolerances; if you don't you're asking for trouble. Working with those kind of tolerances, the drivers themselves typically have more deviation than is caused by losses from the filter components. What other losses or additions the filter components might make, especially the caps, is another matter; I tend to treat that separately. YMMV though.
'"That'll do," comes the cry of the perfectionist down the ages.' (James May The Reassembler)
Website www.wodendesign.com
Community sites www.frugal-horn.com & www.frugal-phile.com
User avatar
Nick
Site Admin
Posts: 15711
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#274 Re: Dungeon Keeper

Post by Nick »

Thats exactly my point, insertion loss for a filter is measured in dB and would refer to the loss in the pass band area. Fs is measured in Hz, so you have a conflict of units.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
User avatar
Scottmoose
Needs to get out more
Posts: 1802
Joined: Sat Sep 08, 2007 11:03 am
Contact:

#275 Re: Dungeon Keeper

Post by Scottmoose »

Fs is just a quick & simple means commonly used for assessing a batch tolerance of drivers. It is not the only thing that varies, and I am not suggesting it is, or that those particular units are comparable. Sensitivity in dB for a given input and frequency is another sometimes used for instance, albeit less convenient, so less common. The point I am making is simply that the insertion losses caused by a reasonably designed high order electrical filter* are typically small compared to the inherent variation in behaviour of most drive units across a range of factors, be they frequency/amplitude response, impedance etc.

*As in, one using components made to close tolerances with low resistance where necessary to avoid undesired / unintended changes
'"That'll do," comes the cry of the perfectionist down the ages.' (James May The Reassembler)
Website www.wodendesign.com
Community sites www.frugal-horn.com & www.frugal-phile.com
User avatar
Dr Bunsen Honeydew
Old Hand
Posts: 1358
Joined: Mon Sep 21, 2009 10:50 am
Location: Muppet Labs

#276 Re: Dungeon Keeper

Post by Dr Bunsen Honeydew »

Drive units do not cause leading and lagging phase. Filters do.
User avatar
Scottmoose
Needs to get out more
Posts: 1802
Joined: Sat Sep 08, 2007 11:03 am
Contact:

#277 Re: Dungeon Keeper

Post by Scottmoose »

And?
'"That'll do," comes the cry of the perfectionist down the ages.' (James May The Reassembler)
Website www.wodendesign.com
Community sites www.frugal-horn.com & www.frugal-phile.com
chris661
Shed dweller
Posts: 2556
Joined: Mon Feb 22, 2010 7:29 am
Location: Sheffield

#278 Re: Dungeon Keeper

Post by chris661 »

Dr Bunsen Honeydew wrote: Tue Apr 18, 2017 8:16 pm Drive units do not cause leading and lagging phase. Filters do.
I'm breaking my own rule by replying to you, but here goes.
Fostex FE126E, with cone treatments and a phase plug. No filters, EQ or anything else here, and the phase shift is quite obviously there.

Image

Chris
User avatar
Dr Bunsen Honeydew
Old Hand
Posts: 1358
Joined: Mon Sep 21, 2009 10:50 am
Location: Muppet Labs

#279 Re: Dungeon Keeper

Post by Dr Bunsen Honeydew »

I would stand corrected if I believed anything those bloody charts tell you, but I don't.
chris661
Shed dweller
Posts: 2556
Joined: Mon Feb 22, 2010 7:29 am
Location: Sheffield

#280 Re: Dungeon Keeper

Post by chris661 »

... and I'm back to ignoring you. That was quick.

Chris
Daniel Quinn
Old Hand
Posts: 859
Joined: Thu Jan 05, 2017 9:19 am

#281 Re: Dungeon Keeper

Post by Daniel Quinn »

That fostex is a full range driver nes pa ?
chris661
Shed dweller
Posts: 2556
Joined: Mon Feb 22, 2010 7:29 am
Location: Sheffield

#282 Re: Dungeon Keeper

Post by chris661 »

Daniel Quinn wrote: Wed Apr 19, 2017 9:08 am That fostex is a full range driver nes pa ?
It is, yeah. Does that matter?

Chris
Daniel Quinn
Old Hand
Posts: 859
Joined: Thu Jan 05, 2017 9:19 am

#283 Re: Dungeon Keeper

Post by Daniel Quinn »

Yes :
User avatar
Nick
Site Admin
Posts: 15711
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#284 Re: Dungeon Keeper

Post by Nick »

I'm breaking my own rule by replying to you, but here goes.
Fostex FE126E, with cone treatments and a phase plug. No filters, EQ or anything else here, and the phase shift is quite obviously there.
well, I would have said that between 300Hz and 5kHz its not. Outside of that range the drive is working as a mechanical filter, so I would expect to see shifts. A good example of how much a 'full range driver' is no such thing.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
chris661
Shed dweller
Posts: 2556
Joined: Mon Feb 22, 2010 7:29 am
Location: Sheffield

#285 Re: Dungeon Keeper

Post by chris661 »

I'm getting closer and closer to full-range out of these, but really that should be a different thread. There's nothing much I can do about the steep drop in the treble, but the bass is getting there. Getting below 40Hz now, but it's costing a lot of headroom.

I see your point about 300Hz-5kHz. It's not perfectly linear (something going on around 1.9kHz, reflected in the SPL graph too), but it's not far off. Mechanical filtering at either end is affecting the phase curve, but I'd argue that's inherent to every driver.

Chris
Post Reply