Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

Dunlavy SC IV schematics ?
Dunlavy SC IV schematics ?
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 24th December 2018, 08:02 PM   #21
HammerSandwich is offline HammerSandwich
diyAudio Member
 
Join Date: Nov 2011
Quote:
Originally Posted by Old'n'Cranky View Post
I was originally led to believe by the (new) owner that the tweeter had been changed.
Now I have them here, I can say they have not been changed.
These speakers are factory original.
D27TG35 or are these early production? Per Andrew Rigby (Dunlavy support) mid-90's, the change happened around serial # 250. I'm not sure which tweeter was used for the 1st year or so of production. Per Stereophile's SC-IV review, it was a Vifa fabric dome but not silk.

Quote:
I have zero plans on changing any component values.

Just updating the solen (shudders) parts for more modern, better manufactured items.
Measurements of the XO's outputs would be interesting - and appreciated! - if you're equipped to make them.
__________________
Rice-Kellogg 2020!
  Reply With Quote
Old 24th December 2018, 08:16 PM   #22
HammerSandwich is offline HammerSandwich
diyAudio Member
 
Join Date: Nov 2011
Quote:
Originally Posted by Dzymytch View Post
It's seems, that there was several revisions of the crossovers. I took the SC-IV crossovers photo when a colleague asked to replace damaged tweeters. Although revision printed in the PCB looks the same, however the crossovers physically looks slightly different (mine have more capacitors and coils).
I believe this is how DAL matched each speaker to the production target. The process was driven by the acoustic results, not matching the prototype's parts. The earlier post about tweaking every speaker in an anechoic chamber applies.

I find DAL's "100% quality control" process quite interesting, and it required such complicated production & testing. Especially with early-90s' technology.
__________________
Rice-Kellogg 2020!
  Reply With Quote
Old 24th December 2018, 10:05 PM   #23
Zoran is offline Zoran  Serbia
diyAudio Member
 
Join Date: Jan 2004
Location: Belgrade
The crossover should be upgraded. Remove all wire-wound resistors and replace with thin film (transistor package) mounted on heat sink. It is a must for tweeter, than for the mids. But You can leave on bass units. Second, replace this small inductor with same value but larger dia wire. Every reactive component should be free from other inside. Otherwise different calculations formulas is valid.
.
Note that thin film Rs are 5W rated without the heatsink. WITH HS rate is 25W.
.
Even this bigger L with 0.8ohms are little insufficient for bass range. Should be 1/2 or 1/3 of that value in DC res.
.
Only after these mods You can try some different brand C of the same value, if You want to experiment. But do not go under in quality and price. I think that present C are good?
Most of the diyers first exchange Cs, this is the easy way, chip way, and opposite steps...
cheers
__________________
###

Last edited by Zoran; 24th December 2018 at 10:08 PM.
  Reply With Quote
Old 24th December 2018, 10:37 PM   #24
cowanaudio is offline cowanaudio  Australia
diyAudio Member
 
cowanaudio's Avatar
 
Join Date: Jul 2004
Location: Canberra
Dunlavy SC IV schematics ?
I would LOVE to do a blind listening test on you once one of these speakers had been modified in this way. It would be foolish to think Dunlavy didn't understand the art of speakerbuilding and actually knew less than you on the subject.
__________________
Don't Procrastinate....Just Do It!
  Reply With Quote
Old 25th December 2018, 12:12 AM   #25
Old'n'Cranky is offline Old'n'Cranky  Australia
diyAudio Member
 
Join Date: Aug 2009
Quote:
Originally Posted by Dzymytch View Post
It's seems, that there was several revisions of the crossovers. I took the SC-IV crossovers photo when a colleague asked to replace damaged tweeters. Although revision printed in the PCB looks the same, however the crossovers physically looks slightly different (mine have more capacitors and coils).
Awesome many thanks for the pics. I always find it interesting to see revisions or changes in the same device. I have seen mention of changes mainly to the tweeter section that others think are to help protect the tweeter more. There are many posts around talking of destroyed tweeters.

Quote:
Originally Posted by HammerSandwich View Post
D27TG35 or are these early production? Per Andrew Rigby (Dunlavy support) mid-90's, the change happened around serial # 250. I'm not sure which tweeter was used for the 1st year or so of production. Per Stereophile's SC-IV review, it was a Vifa fabric dome but not silk.

Measurements of the XO's outputs would be interesting - and appreciated! - if you're equipped to make them.
I haven't removed any drivers to confirm model numbers (yet ) as I don't want to risk marring the cabinets, felt or gaskets etc. If I do go that far I shall report what I find.

These are serial '10xx - A'. The date code on the caps are predominantly 1996 with one coded 1995. If I assume (dangerous I know) the caps were bought in low volume batches to suit the time of production, I'm guessing the speakers would have been built somewhere 1996 onwards.

Measurement of the crossover output, I'm not sure how I'd do that.

I believe most often over think the potential alteration of 'sound' from crossover changes as I believe the room has far more effect than any other variable.

For example. My friends room is massive so it should suit these speakers nicely. Something like 10 meters wide x 9 meters deep. Ceiling hight around 3 mtrs. Speakers were 6 mtrs apart and best listening position is at the back wall.

My room is an 'L' shaped lounge with the main area a paltry 4 mtr wide by 6 mtr deep with 2.4 mtr ceilings, so on the edge of being too small according to Mr Dunlavy. Worse still the speakers are barely 2 mtrs apart with the listener about 2.5 mtrs from the speakers.

Yet, in friends room they sound absolutely disgusting. lack of bass, very recessed mids, almost ear shredding treble.

And in my room, everything changes. There is bass there, it does go deep, but it feels restricted. Probably as I'm used to ported speakers. And the main speakers in there are 15" JBL's.

Midrange is far better but still a tiny bit recessed, treble is the biggest improvement, still a touch grainy but better although (to me) the tweeters still need a fly poop more attenuation.

Dagnabit, now I want to remove and investigate the drivers properly

Oh and honestly I'm enjoying the conversation about step response etc, so please, continue.
  Reply With Quote
Old 25th December 2018, 02:54 AM   #26
googlyone is offline googlyone  Australia
diyAudio Member
 
Join Date: Nov 2006
Location: Adelaide, South Australia
Dunlavy SC IV schematics ?
Hmmm.

Unless you really. Really. Know what you are doing, and have a pretty solid measurement system then I feel happy to go out on a limb and say that anything you do th these speakers will result in them being less accurate than they started.

I worked across the road from dunlavy in the early 90s, and had some interaction with him and with the spin offs that came out of his company.

They knew the science and process in a way few do.

Yes, as in all high end audio there were lashings of hype. But if you think "technology has moved" you are being rather optimistic.

As an ardent advocate of DSP crossovers, I agree that active would indeed be a "good thing". But here is the rub...

The whole essence and ethos of dunlavey was "perfect impulse response".

This came out in a couple of conversations I has with him. His passion was that a speaker with a perfect impulse response would by necessity have a great amplitude and phase response.

This leads to (not exclusively but certainly practivally) a first order crossover.

If this doesn't make sense, leave those speakers well alone and go screw with some generic speakers.

They started life as high end speakers hand tuned by experts.

I love DIY and love building stuff - but on these would do a check out and polish up.
  Reply With Quote
Old 25th December 2018, 02:58 AM   #27
rayma is offline rayma  United States
diyAudio Member
 
Join Date: Apr 2011
Quote:
Originally Posted by googlyone View Post
leave those speakers well alone and go screw with some generic speakers.
They started life as high end speakers hand tuned by experts. I love DIY
and love building stuff - but on these would do a check out and polish up.
Wise words.
  Reply With Quote
Old 25th December 2018, 04:39 AM   #28
Hanze Khronye is offline Hanze Khronye  Australia
diyAudio Member
 
Join Date: Jan 2018
Quote:
Originally Posted by rayma View Post
Wise words.
I've changed out parts on Duntechs XO's with very good results. Do so 'without fear' but measure the values of the components before you do, and be sure to use the exact same values, they were built in matched pairs (speakers), and absolute values will be important, and not necessarily the same WRT each XO.

Last edited by Hanze Khronye; 25th December 2018 at 04:48 AM.
  Reply With Quote
Old 25th December 2018, 07:39 AM   #29
mark100 is offline mark100  United States
diyAudio Member
 
Join Date: Dec 2010
Dunlavy SC IV schematics ?
Quote:
Originally Posted by googlyone View Post
Hmmm.

Unless you really. Really. Know what you are doing, and have a pretty solid measurement system then I feel happy to go out on a limb and say that anything you do th these speakers will result in them being less accurate than they started.

I worked across the road from dunlavy in the early 90s, and had some interaction with him and with the spin offs that came out of his company.

They knew the science and process in a way few do.

Yes, as in all high end audio there were lashings of hype. But if you think "technology has moved" you are being rather optimistic.

As an ardent advocate of DSP crossovers, I agree that active would indeed be a "good thing". But here is the rub...

The whole essence and ethos of dunlavey was "perfect impulse response".

This came out in a couple of conversations I has with him. His passion was that a speaker with a perfect impulse response would by necessity have a great amplitude and phase response.

This leads to (not exclusively but certainly practivally) a first order crossover.

If this doesn't make sense, leave those speakers well alone and go screw with some generic speakers.

They started life as high end speakers hand tuned by experts.

I love DIY and love building stuff - but on these would do a check out and polish up.
Enjoyed your post, thanks.

Yes, if it isn't intuitively obvious that a perfect impulse equals flat amplitude and flat phase,
and also obvious that a first order crossover is the closest thing you can get to flat phase in the world of IIR...
well, time to leave the speakers be.

But, if those points are clear, and one has the measurement skills as mentioned needed, then I'd hazard a guess the Dunlavey's are probably some of the easiest speakers to tinker with that there are.
Because you have to reason that first order crossovers can only be used on designs that have broad, well behaved, acoustic overlap between drivers. Most of the work has already been done....it should be easy to tie together, especially active.

I remember John D's posts from way back, usenet if I remember correctly....
What a down to earth, nice, smart guy. I remember him saying Sony MDR 7506 headphones were his reference for tuning his speakers. I thought, what a real world dude...doesn't care about impressing people with expensive gear comparisons.

He was also one of the ones who started me thinking about linear-phase.
IMO, that's all he was really advocating, with first order being as close to linear as then was possible. (and easily implemented without additional all-pass networks).
  Reply With Quote
Old 25th December 2018, 09:02 AM   #30
celef is offline celef
diyAudio Member
 
Join Date: Nov 2012
I belive those scr poly caps are of high quality that also are immune to ageing, so i can not see why these should be replaced? The drivers however may have changed over time.
  Reply With Quote

Reply


Dunlavy SC IV schematics ?Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Dunlavy IV Question maxpou Multi-Way 0 9th July 2010 08:11 PM
Help with dunlavy SM1 crossover ebenai Multi-Way 12 27th December 2008 12:21 AM
Crossover Schematics Dunlavy SC-V dazzdax Multi-Way 0 29th October 2006 01:00 AM
dunlavy sc-1 maxpou Multi-Way 4 2nd May 2006 11:23 PM
Dunlavy out of business? eLarson Everything Else 0 10th November 2002 01:16 PM


New To Site? Need Help?

All times are GMT. The time now is 02:20 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki