Jump to content

acg

Deep End DIY - My first speaker project

Recommended Posts

have you tried bolting them face to face, or at least mount them close together, and playing them together but out of phase? it should cancel/reduce some of the the noise and help break them in evenly with respect to each other

 

 

I wouldn't over-think this   ;)

Share this post


Link to post
Share on other sites

Ok,  got serious today.  Firstly, I fed 80Hz 85dB through the pair of 8M for 30 minutes and did a quick check...Fs barely moved...I thought this may happen.  So for the next 3.25 hours I jammed 80Hz through them at 90dB and the results are in:  Fs=80.7Hz and 82.7Hz, so very close to the spec of 81Hz.  Hopefully I will be able to give them both a bit more time in coming days and see where they end up, but I am happy now, and Dave/Chris were right the Fs did change a lot (106Hz to 81Hz or 30% drop) with time near the resonant frequency at somewhere above half Xmax.  To date roughly 6 hours of 80Hz or 100Hz tone at 85dB or more has been applied to these drivers.

Share this post


Link to post
Share on other sites

 Dave/Chris were right 

 

I am probably closer to being wrong actually ... I didn't expect it to take this long but I think this driver is a bit unique being so stiff so that's what caught me out.

Share this post


Link to post
Share on other sites

It's good to here these have taken less time to break in than what I would have expected. I will be doing the same experiment with some peerless drivers shortly.

Share this post


Link to post
Share on other sites


In the spirit of "unless there are photos it never happened", for what it is worth here is a photo of the Fane Studio 8M's punching out 95dB at 80Hz.  They are 8" drivers, stiff suspension with a large magnet...really "muscular" looking drivers I reckon.

 

(Sorry about the bad light)

 

 

Caught near the top of the excursion...

post-139669-0-13435800-1421992896_thumb.

 

 

Cleaner shot from above...

post-139669-0-92440600-1421992901_thumb.

 

Check those muscular magnets...

post-139669-0-35403600-1421992905_thumb.

 

 

 

Share this post


Link to post
Share on other sites

As an addendum to the "driver break-in" escapades, I have played around a little more in an attempt to get a better understanding of how a driver operates.

 

So, yesterday morning I did something that I had thought about for a while.  When I had previously run the impedance sweeps, the driver had been running and active and warm.  By warm I mean that I could feel a little warmth in the magnet when I picked them up to bring back to the office and plug into DATS.  Fs had eventually got down to near spec, about 81Hz for both drivers.  Yesterday morning I measured the drivers cold, straight out of the box and not used for several days.  They both measured Fs=96Hz so I ran a little low level signal through them in the office for some time but the warm Fs only dropped to 88Hz.   Mmmmmm.  So I plugged them back into the Denon AVR at the other end of the house and gave them 90dB+ for four hours.  Then I stopped them, jumped on the pushbike, picked my son up from school and came back to measure them after they had sat for about an hour:  Fs=78Hz for both drivers.  Excellent, that is lower than before and now both drivers are the same.

 

This morning I measured the drivers from cold again and they were back to Fs=96Hz.  So I jammed 10 minutes of 80Hz 90dB+ through them and then remeasured:  Fs = 78Hz for both.  Awesome.  I now declare these drivers largely broken in (after 11 hours of signal).

 

What is really interesting to me, and is probably exaggerated by the particularly stiffly suspended cones of these drivers, is the change in impedance in a short space of time when they are used from cold:  96Hz - 78Hz.  That is decent evidence to me that a loudspeaker needs to "warm-up" for a while before it gets to its optimum performance, and also that you should not measure speakers or drivers cold...make them sweat a bit first.

 

Cheers,

 

Anthony

Share this post


Link to post
Share on other sites

What is really interesting to me, and is probably exaggerated by the particularly stiffly suspended cones of these drivers, is the change in impedance in a short space of time when they are used from cold:  96Hz - 78Hz.  That is decent evidence to me that a loudspeaker needs to "warm-up" for a while before it gets to its optimum performance, and also that you should not measure speakers or drivers cold...make them sweat a bit first.

 

What happens to sensitivity with that change in temp?

 

How long does it take to cool down?

 

Is there any way to get a measure of the winding conductor temp?

 

That warm-up might not happen as well with music signal as it does with a continuous 80Hz sine wave. The crest factor of the signal (avg vs peak power) and relatively large thermal mass will mean that thermal effects are much less with a normal music signal. 

 

This is interesting though because I've normally thought about long term thermal compression and (very) short term thermal modulation not about the effect on the impedance curve and resonance point.

 

 

Cheers,

Chris

Edited by hochopeper

Share this post


Link to post
Share on other sites

What is really interesting to me, and is probably exaggerated by the particularly stiffly suspended cones of these drivers, is the change in impedance in a short space of time when they are used from cold:  96Hz - 78Hz.  That is decent evidence to me that a loudspeaker needs to "warm-up" for a while before it gets to its optimum performance, and also that you should not measure speakers or drivers cold...make them sweat a bit first.

 

Ah, yeah... we should have mentioned this earlier.   Parameters depends on the driver resistance, which depends on temperature.     Measure them cold, as they will never get hot when loaded in your horn.

Share this post


Link to post
Share on other sites


What happens to sensitivity with that change in temp?

 

 

Did not look at the sensitivity and did not store the sweeps.  Will have a look tomorrow.

 

 

How long does it take to cool down?

 

 

Yesterday, after a proper flogging the drivers measured 78Hz after an hour with no signal.  May well be a function of how warm the voice coil is when the signal is stopped.

 

 

 

Is there any way to get a measure of the winding conductor temp?

 

 

I do have multimeter that seems to take accurate temperatures, but I am not sure just where I would need to poke the probe and whether that spot would be accessible.

 

 

 

That warm-up might not happen as well with music signal as it does with a continuous 80Hz sine wave. The crest factor of the signal (avg vs peak power) and relatively large thermal mass will mean that thermal effects are much less with a normal music signal. 

 

This is interesting though because I've normally thought about long term thermal compression and (very) short term thermal modulation not about the effect on the impedance curve and resonance point.

 

 

I am thinking about this also from the perspective of matching a SET amp to the horn, and in particular the OPT.  I used 10 minutes of loud 80Hz as a starting point...I did not actually expect the Fs to drop so quickly.  If I do it again I will try with a shorter interrupt, say 2 minutes or 5 minutes.

Share this post


Link to post
Share on other sites

Ah, yeah... we should have mentioned this earlier.   Parameters depends on the driver resistance, which depends on temperature.     Measure them cold, as they will never get hot when loaded in your horn.

 

This makes sense Dave.  Of course everything changes when the 8M's go into a horn with a back-chamber.  Tuning that back-chamber to the best sound is apparently quite a process to do perfectly, and I do intend to do it just as Romy states on his website.

 

From my notes taken from Goodsoundclub.com:

 

 

Want to tune the driver resonance to match the horn cutoff.  The last handful of Hz approaching the horn cutoff will alter the sound of the horn dramatically.

1.       Fill entire backchamber with foam and make the driver very, very over-damped.  First cover the driver with paper and spray in the expanding foam.  Listen for 2-3 days and learn to hate the over-damped horn.

2.       Open back chamber incrementally and listen for the best sound.  There is no rush.

3.       When the right sound is found measure Fs.

4.       Sculpt the backchamber foam so that the Fs equals your preferred value with the backchamber closed. 

 

 

 

As you can see it involves over-damping the back-chamber and then doing plenty of listening.  It will be a very interesting experience when I get to that stage.

Share this post


Link to post
Share on other sites

I am thinking about this also from the perspective of matching a SET amp to the horn, and in particular the OPT.  I used 10 minutes of loud 80Hz as a starting point...I did not actually expect the Fs to drop so quickly.  If I do it again I will try with a shorter interrupt, say 2 minutes or 5 minutes.

 

With music you'll still never have 2mins of 80Hz at those levels. I hadn't even thought about the horn loading so yeah even smaller signal levels. It just won't get any sort of thermal effects, that's the point of high sensitivity. Dave's right. Measure cold.

Share this post


Link to post
Share on other sites

I get excited when I receive an email saying there is a fresh post for this and it is all very interesting but  when will we see some pictures of the horns being turned ?

Share this post


Link to post
Share on other sites


I get excited when I receive an email saying there is a fresh post for this and it is all very interesting but  when will we see some pictures of the horns being turned ?

 

Very close now.  While the wife is away, the husband will play (this weekend).

Share this post


Link to post
Share on other sites

So, I have a very "first world" problem.  I am having trouble deciding on the type of paint finish that I am going to go for with these speakers.  I am thinking one of three ways:

 

Option 1 - Look-At-Me high gloss or piano finish.

 

AcapellaTE-3.jpg

 

Look at all those surfaces peering back at me.  There is certainly no forgetting they are in the room.

 

 

Option Two - Sensible Gloss (not piano finish)

 

23r96vk.jpg

 

Hi @@tuyen, I hope you don't mind me pilfering your photo.  A sensible gloss without being over-the-top look-at-me!

 

 

 

Option 3 - Very Sensible and Pragmatic Matt finish

 

Romy_ListeningRoom_Winter.JPG

 

Sort of fades into the room without drawing undue attention to itself.  The horns that I am building are actually close replicas of the bottom photo.

 

 

 

My personal preference at this stage is actually towards the matt-finish, but some ego-centric part of me wants the shiny piano-gloss speakers as well.  Given that the speakers are 2m tall and will naturally dominate the room, especially if I end up with the bass line arrays perhaps it is best to for them not to gather undue attention with all things shiny.

 

Colour is likely to be black.

 

Any opinions/observations/recommendations or alternatives are welcome.

 

Anthony

Share this post


Link to post
Share on other sites

Any opinions/observations/recommendations or alternatives are welcome.

 

The lighting is very different between those photos. Option 1 has a bright flash + bright in room lighting, option 2 has lots of in room light (a couple of bar fluoros by the look) and option 3 is quite a dimmly lit room ... so those lighting differences are really over-emphasising the differences.

 

How much work goes into keeping those really shiny large horns clean and looking so good?

Edited by hochopeper

Share this post


Link to post
Share on other sites

I would go satin or a pearlescent finish over the matt or gloss

It's the best of both worlds by blending into the shadows when dark and muted twinkling when highlighted

You also need to consider that the finish needs to be serviceable for cleaning ect

This horn is a satin finish

post-112724-0-28770200-1422503044_thumb.

Share this post


Link to post
Share on other sites


The lighting is very different between those photos. Option 1 has a bright flash + bright in room lighting, option 2 has lots of in room light (a couple of bar fluoros by the look) and option 3 is quite a dimmly lit room ... so those lighting differences are really over-emphasising the differences.

 

How much work goes into keeping those really shiny large horns clean and looking so good?

 

Yes the lighting is very different between photos, but I only had time for a quick web search in order to find photos to use as examples.  I've tried to take photos of piano finish items before and the ambient light needs to be just right to get any sort of reasonable image, and forget about the flash, you will just see a ball of light.  Perhaps in a well lit room the glossier finishes would be more attractive (the wrong mat could potentially look awful) but I think that as more light is taken from the room that the mat finish would come into its own, or more specifically the shiny look-at-me-ness is diminished.  I really don't want to see the elephant in the room...ha ha ha...oh that could be true...sigh.  

 

The colour will be black, so I think that dust is going to be very visible regardless of the amount of light the paint reflects.  From the dust perspective I should go for white but then they are going to look much bigger than they would if black.  Scratch wise, the piano finish has got warts on it, that is for sure.

 

 

I would go satin or a pearlescent finish over the matt or gloss

It's the best of both worlds by blending into the shadows when dark and muted twinkling when highlighted

You also need to consider that the finish needs to be serviceable for cleaning ect

This horn is a satin finish

 

 

That is a good idea Full Range.  I did not even think of a satin finish.

Share this post


Link to post
Share on other sites

Well if you make it big enough then you wont see it i supposed... 😊

Anyhow, impressive stuff mate, steep learning curve too ðŸ‘ðŸ‘

Share this post


Link to post
Share on other sites

matt black all the way .... Romy talks a lot of trash, but what he says about the aesthetic design of a system, I do agree with.

Share this post


Link to post
Share on other sites

Anyhow, impressive stuff mate, steep learning curve too

 

Very steep.  I have been thinking about things recently that I would never have considered even remotely interesting a couple of years ago.

 

Unless something comes out of my left-field,  I think that I have a grip on the macro-elements of what is required to complete this project.  There are areas in which I require more knowledge so I will cover those topics as they arrive. 

Share this post


Link to post
Share on other sites

matt black all the way .... Romy talks a lot of trash, but what he says about the aesthetic design of a system, I do agree with.

 

Yes yes and yes.

 

Earlier I sat up in the room into which this system is to go and tried to think about the things I would change in there.  Different paint colour...yes.  New carpet...yes.  Change the wallpaper...no.  There is this semi-gaudy silver/gold wallpaper on two of the walls that is really just very beautiful.  My intention when I re-do that room is to work with that wallpaper and I think that it will provide all the "sparkle" that the room will need.  Combined with a wood panel ceiling, some exposed brick and the busy wallpaper, perhaps a less busy speaker system will be the best fit.

Share this post


Link to post
Share on other sites

What the?

 

post-139669-0-17818600-1422600098_thumb.

 

 

 

Yes, I chose an "agricultural enamel" for my speakers.  We will see how that goes.

Share this post


Link to post
Share on other sites

Had a lovely weekend with just my 6yo son.  He was so helpful.  We drilled, jigsawed, sanded, mowed, re-arranged the shed together.  He also swept, climbed trees, folded tarps, practiced his tennis drop-shot, occasionally had a short spells on the iPad in the afternoons and most importantly from time to time on Sunday ferried out the cricket score to me.  Dads should have plenty of weekends like that with their sons, it was awesome.

 

In the meantime I got plenty done.  I shifted the lathe on the lathe table so that it will better cope with a heavy weight being turned outboard, plus I re-wired its electrics and stuffed around with the motor mount and a few other little things to get it running relatively smoothly and vibration free.  In other words I gave the lathe a tune-up.  Then I could not help myself and I screwed a lump of MDF to an aluminium faceplate, cut it round on the lathe and then cut a recess to take the wood screws that are used to attach the horns to the faceplate.  I wanted to get an idea of how the tools worked and the lathe behaved so I spent about 20 minutes roughing out one of the Midrange Horns.  After the Bosch jigsaw tool-quality revelations I had taken a punt and spent a few dollars on a decent tool.  As you can see in the photos below the MDF came off in streamers...it was very fast and very easy to use.

 

This short time with the lathe working has cemented some of my ideas for turning these horns and I will now move on with fabricating a special tool and further modifying the lathe before I turn anything to shape.  Sunday was spent gluing boards together:  see the photo below of two glued UpperBass Back-Chambers and two Fundamentals Horns (will be turned in two segments).

 

Two pairs of Fundamental Horns, Upperbass Back-chamber and Midrange Horns with the Upperbass Horns stacked floor to roof in the background.

 

post-139669-0-34967000-1422831819_thumb.

 

 

 

Midrange Horn roughed out.

 

post-139669-0-12017800-1422831829_thumb.

 

 

Midrange Horn roughed out from the side.

 

post-139669-0-27497000-1422831837_thumb.

 

Share this post


Link to post
Share on other sites

Awesome work getting your son involved. I really feel that it is our duty to pass on our knowledge of how to work with our hands to our kids. They get computers and technology pushed on them from all around. My old man taught me a lot but I have learnt more and am trying to teach my kids.

Had the eight year old helping me fibreglass some tweeter mounts for the car. Obviously he was up to his elbows in resin and Matt two minutes later. But I saw his little mind thinking of how he could shape glass.

I only learnt to glass last week. Figured pass my mistakes on as well.

Sorry to bomb your thread but your comments about the son helping really made me appreciate this little moment with my son.

Back on topic. Such a brave build. I would say inspiring, but that term is over used in this reality tv world. Amazing how much work is required to bed your drivers in. I had never thought about that. Please Keep us informed.

Sent from my iPhone using Tapatalk

post-150024-142283580889.jpg

Edited by ben54b

Share this post


Link to post
Share on other sites

I love seeing my kids make connections or having light-bulb moments and then thinking about how to do something or how they can apply what they learned elsewhere. 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Classifieds Statistics


    Currently Active Ads

    Total Sales (Since 2018)

    Total Sales Value (Last 14 Days)

    Total Ads Value (Since March 2020)
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By gypr1961
      Item: Avantgarde Zero 1 XD Active Speakers DSP
      Location: Brisbane
      Price: $17,500 ONO
      Item Condition: Mint
      Reason for selling: Time for a change
      Payment Method: Pickup - Cash, Paypal, COD Only
      Extra Info:

      These are the top of the line model, above the pro model and come with DSP, digital and an analogue (A/D card) for turntables etc.
       
      They are incredibly dynamic! They sound just as good when theyre shaking the house or playing whisper quiet. 
       
      I have all original packing so transport is not an issue
       
      As im going to need a complete new system Im happy to look at trades
       
       
      Specs can be found here https://www.avantgarde-acoustic.de/en/products/zero-serie/zero-1-xd.html
       



    • By leqt1969
      Item: Avantgarde Acoustic UNO speakers
      Location: Bexley NSW
      Price: $8,500 ONO.
      Item Condition: Used but in great condition, superb sonically.
      Reason for selling: Going different direction
      Payment Method: Pickup - Cash
      Extra Info: Advertise on behalf of a friend in Bexley NSW who doesn’t have SNA account.
      Grab your chance.
      Avantgarde speakers are rarely seen on second hand market. These speakers are in great condition and sound superb. Still have original box but pick up preferred due to weight.
      Audition can be arranged for serious buyers.
       
       
      Photos: Advertisements without photos of the actual item will not be approved.



    • By La scala
      Item: Klipsch La Scala speakers 
      Location: Perth metro
      Price:  $3500
      Item Condition: Great for their age, 1978 ish Alnico 
      Reason for selling: Told to shed some gear
      Payment Method: Pickup - Cash,  Bank Tranfer COD Only
      Extra Info: East coast buyers, can do live video demo via FaceTime 
      These have the favoured Alnico Magnets, serviced X Overs and updated Mundorf Capacitors, some body bracing to tighten bottom end.
      All drivers work spot on.
      Sound wise, these have a uncanny ability to project a very large wall of sound with fine detail and dynamic authority.  Impressive as I am normally into Electrostats, Planar and Ribbon speakers. Very versatile and allow use of Set Valve Amps due to their 100db efficiency. 
       
      Photos: Advertisements without photos of the actual item will not be approved.




    • By MarcAL
      Item: Altec Lansing MR II 564 Large Format Mantaray Horns
      Location: Sydney South
      Price: $220 the pair or $125 each
      Item Condition: Used, good original condition, see pictures
      Reason for selling: NLR
      Payment Method: Pickup - Cash, Paypal, COD Only
      Extra Info: Altec Lansing MR II 564 Mantaray Constant Directivity Horns for large format 1.4" compression drivers.
      PM me if you require large compression Altec drivers to suit.
      Nominal Dispersion Angle: 60 x 40 degrees.
      Useable Low Frequency Limit: 500Hz.
      Construction: Heavy duty, weather resistant polyester/fiberglass.
      Finish: Standard Altec grey with a few minor scratches, can be resprayed another colour for an additional cost.
      Suitable Drivers: Many 1.4" throat compression drivers or Altec Lansing Large Format Compression Driver models 288, 290, 291, 299 etc.
      Small format compression drivers can also be used with the use of an adapter.
      Data Sheet: http://pdf.textfiles.com/manuals/STARINMANUALS/Bosch - EV/Archive/Altec/MRII 564.pdf
      Weight: 2.1kg each.
      Shipment: Will send interstate at purchasers expense, free delivery within Sydney.
      Pictures:




       
    • By MarcAL
      Item: Altec Lansing MR II 564 Large Format Mantaray Horns
      Location: Sydney South
      Price: $225 for the pair
      Item Condition: Used, good original condition, see pictures
      Reason for selling: NLR
      Payment Method: Pickup - Cash, Paypal Only
      Extra Info: Altec Lansing MR II 564 Mantaray Constant Directivity Horns for large format 1.4" compression drivers.
      Nominal Dispersion Angle: 60 x 40 degrees.
      Useable Low Frequency Limit: 500Hz.
      Construction: Heavy duty, weather resistant polyester/fiberglass.
      Finish: Standard Altec grey with a few minor scratches, can be resprayed another colour for an additional cost.
      Suitable Drivers: Many 1.4" throat compression drivers or Altec Lansing Large Format Compression Driver models 288, 290, 291, 299 etc.
      Data Sheet: http://pdf.textfiles.com/manuals/STARINMANUALS/Bosch - EV/Archive/Altec/MRII 564.pdf
      Weight: 2.1kg each.
      Shipment: Will send interstate at purchasers expense, free delivery within Sydney.

      Pictures:






×
×
  • Create New...