rp3703

DIY Studio 100
« on: September 02, 2017, 10:01:17 AM »
I have read all the other threads on multiple forums about this same objective but most of them run off on a tangent about how one can improve on the design and eventually link to a bunch of similar but far different speaker designs. If the design needed improvement then why the hell are people still forking over $2600($2595 Vintage King) for a set of these things? On that same note, how does $450 worth of drivers, $40 worth of crossover parts and some absorption material placed inside an MDF box justify a $2600 price tag?

Now yes, if I was making these one at a time by hand, I’d probably loose my ass selling them for $2600 but when it comes to DIY, you can’t count your labor. There is also something to be said for resale value. A quick check of eBay shows plenty of sets of these speakers in the $1500 range but some going for as much as a new set. I guess this is more of a personal decision.

So this is all the information I have been able to gather so far.
1. The boxes measure 16” (406mm) high, 8” (203mm) wide and 10” (254mm) deep and are made with veneered 3/4” MDF. The boxes themselves look to be constructed the same way most speaker boxes are with no internal bracing.  The sides appear to be mitered to the top and bottom(although it would make more sense to use a mitered lap joint). The front and back appear to be set into a lap joint created by the top, bottom and sides.
2. The woofer is a ScanSpeak 18W/8542-00 which sells for $195 at Vintage King or $174.70 at Madi Sound.
3. The tweeter is a SEAS 25TFFC which sells for $66.50 at Madi Sound under the item number (H0519). Maddi sound suggests an optional replacement for the 25TFFC tweeter is the 27TFFC which sells for $45. It is supposed to have the exact same performance of the 25TFFC, the only difference being that the connection terminals protrude out one side which means the hole in the speaker box will need to routed to accommodate. If you look at the picture of the box I’ve attached, you will see this same routing, which leads me to believe the 27TFFC is what has been used in the monitors for a while now. I’m still not sure which way to go on this one.
4. The bass reflex hole is about 2” (5.5cm) in diameter and about 4-3/4” (12cm) in length. I still have not found a place to purchase this but I have not really looked either.
5. The crossover network(schematic and pictures attached) consists of the following components:
   L1- 1.8 MH(measured 1.789MH & 0.391 DCR) Which can be purchased here http://www.falconacoustics.co.uk/audio-inductors-ferrite-air-core-iron-dust/hp071-high-power-low-loss-ferrite-core-031-040mh-audio-inductor.html)
   L2- 0.33 MH(measured 0.304 MH & 0.273 DCR) Which can be purchased here http://www.falconacoustics.co.uk/audio-inductors-ferrite-air-core-iron-dust/hp071-high-power-low-loss-ferrite-core-151-180mh-audio-inductor.html)
   R1- 4.7 ohm 9-10W?(Hard to read on the picture) Probably 9W ceramic resistor. The one in the photo is manufactured by Expotus and can be purchased through the same company as the inductors but I’m sure any manufacturer will do.
   C1- 2.2uf 250V metal film or foil capacitor, manufactured by Vishay BC MKT
   C2/3- 4.7uf 100V metal film or foil capacitor, manufactured by Expotus

All components are attached to a PCB with wide plated through holes that bolt onto the studs of the rear speaker terminals. The speaker terminals are attached to a 1/2 piece of MDF that is attached to the inside of the rear panel of the box(refer to attached photos). Although there is a plastic insert on the rear of the box where the speaker terminals are located, other that aesthetics, I see no need for it. A similarly functioning PCB could easily be made by using single side copper clad FR4 board and just scraping off the copper where necessary although there will need to be a way to allow the nuts used to secure the PCB to the speaker terminal posts to make contact with the copper on the opposite side of the PCB. Maybe through the use of tinned eyelets. Any ideas here would be appreciated.

—Now here is where my research falls flat—

6. The inside of the box is lined in various places(see photo) with unknown sized pieces of bitumen low frequency absorption pads that can be found here: http://www.qtasystems.com/loudspeaker-components/loudspeaker-damping.html More info on these pads can be found here: http://www.qtasystems.com/loudspeaker-articles/how-to-damping.html. At first I thought that maybe these pads had felt attached to the bottom of them but now I’m thinking they are just the 5MM thick ones sold at the previous link. I would think the sizes could be approximated based on the attached photo without affecting the sound too much and they look to be stapled to the inside of the box.
7. The rest of the inside of the box seems to be filled completely with 1”-1.5”(but was stated by the person who took the picture of it as 15mm(about 5/8”)) thick foam. This foam is the most frustrating piece of the Studio 100 because, as is mentioned in this same article http://www.qtasystems.com/loudspeaker-articles/how-to-damping.html, the structure of the cells that make up the foam itself can affect which frequencies and how much of these frequencies end up getting absorbed. So, in my mind, getting the wrong foam could completely alter the sound of the speaker.  Now, with that in mind, and this is a leap here but I would be willing to bet the foam is similar if not exact in specs to this foam http://www.falconacoustics.co.uk/cabinet-parts-accessories/dedshete-wadding-acoustic-foam-gasket-ls35a-loudspeaker-cabinet/ls35a-acoustic-foam.html which was used inside the popular LS3/5A speaker that was manufactured in the UK for the BBC as a reference monitor. The specs on the foam state that it’s density is 23.5-25.5 kg/m3. If you look for other acoustical foam that is made for the inside of speaker boxes that also happens to be made in the UK, they are all 23.5-25.5 kg/m3 in density. Again, this is only a guess and I may be giving more importance to using the exact same kind of foam than it deserves but I’m still pretty wary about starting this project not being completely sure, so any help here would be greatly appreciated. Judging from the pattern of overspray on the foam in the attached picture, the large side pieces are cut first to cover the entire sides of the inside of the speaker box. Then the top and bottom are cut to go between the side foam pieces and front to back of the speaker box. After that, the back is cut to fit between the side foam and the top and bottom foam and gets sandwiched between the speaker terminals and the crossover.

So lets add it up. The inductors, resistors and speakers can be purchased from here http://www.falconacoustics.co.uk for $482 shipped(@ current exchange rate). Using all Vishay brand polyester capacitors purchased from Newark will run $13.28 shipped. The cabinet material will run around $50-60(Depending on veneer and does not include finishing). The bitumen low frequency damping material will cost $80(I do not know shipping cost but will assume $20, so $100 total). Two 4” x 6” copper clad FR4 boards shipped from china cost $3 shipped. That comes out to $645.28 but does not account for the speaker terminals, port, the internal speaker wire and the foam. Given that the foam will more than likely have to be purchased from the UK, I’d guess that these unaccounted for parts will cost an additional $100. So that would bring the entire material cost of these speakers to around $750.

At $750, we are at about half of what a used set of the real deal would cost. Given that a used set of these speakers would probably be able to be resold for the same $1500 price they can be purchased for, if resale value is a concern, then it’s probably not worth the cost savings to build a set yourself. If resale is not important to you and you have the skills to build a set of these yourself, a $750 cost savings may be worth the effort. It should also be mentioned, since we are talking about pro’s and cons of this project, that the ScanSpeak woofers used in these speakers are notorious for deteriorating speaker surrounds. So a used set will be that much closer to that happening. At the same time, a brand new set of woofers will need break-in time. Something a used set should not need.


rp3703

Re: DIY Studio 100
« Reply #1 on: September 02, 2017, 10:06:57 AM »
Crossover Schematic

rp3703

Re: DIY Studio 100
« Reply #2 on: September 02, 2017, 10:07:42 AM »
Pic of crossover.

rp3703

Re: DIY Studio 100
« Reply #3 on: September 02, 2017, 10:08:22 AM »
pic of the foam

Le Roux

Re: DIY Studio 100
« Reply #4 on: September 06, 2017, 06:38:01 AM »
I got info from member Whoops a few years ago about this project.

He said the crossover schematic floating around the internet had incorrect polarities.

I never started the project yet, so maybe he can chime in on this?

rp3703

Re: DIY Studio 100
« Reply #5 on: September 10, 2017, 10:32:43 PM »
Thanks for the schematic fix.

Whoops

Re: DIY Studio 100
« Reply #6 on: September 13, 2017, 10:29:13 PM »
Hi,
I built quite a few of these already






Whoops

Re: DIY Studio 100
« Reply #7 on: September 13, 2017, 10:31:14 PM »
Next to an original one.

This one I built has the tweeter in the middle because it was supposed to be a center channel of a 5.1 system.
At least that was what was asked I dont know if it was used that way

Whoops

Re: DIY Studio 100
« Reply #8 on: September 13, 2017, 11:01:48 PM »
rp3703 your first post is too big and too dense, a lot of people will simply give up reading it.

In the end of it I didn't understand your intentions, if you want to build a pair for yourself or not.
you got the accounting wrong you will spend much more money than that building a pair, but hey you might enjoy the process.

I enjoyed mine

Some corrections:

"the boxes ...  are made with veneered 3/4” MDF. "

It's MDF but not Veneered, it has a plastic laminate on top of the MDF imitating cherry or wood patterns.

My diy clones had a cherry wood laminate on top of the MDF and then were veneered but not the orignal ProAc ones.

I don't know what is 3/4”, but I remember the MDF is 2cm thick



"2. The woofer is a ScanSpeak 18W/8542-00 which sells for $195 at Vintage King or $174.70 at Madi Sound. "

Well supposedly the mid-range woofer Proac uses is a modified version of the 18W/8542-00, and not the standard 18W/8542-00 available in the market.
If that's true or not, and the only difference is the printed logo I don't know.
But nowhere Ive seen talks about a modified tweeter, but the modified woofer always comes in


"4. The bass reflex hole is about 2” (5.5cm) in diameter and about 4-3/4” (12cm) in length. I still have not found a place to purchase this but I have not really looked either."

I searched a lot, wasted a lot of time (time is money, so the ProAc price tag seems quite right thinking of it nowadays) looking for the proper bass reflex tube.
I only found one source for it.
I advise you not to waste your time looking for it like I did. I can search the source details and let you know



"The specs on the foam state that it’s density is 23.5-25.5 kg/m3."

Nothing exotic about the foam, or about anything in the speaker at all, it's just normal foam. Get the dimensions right and use standard density move on


"At first I thought that maybe these pads had felt attached to the bottom of them but now I’m thinking they are just the 5MM thick ones sold at the previous link. I would think the sizes could be approximated based on the attached photo without affecting the sound too much and they look to be stapled to the inside of the box."

The bitumex pads are stapled to the mdf. the dimensions dont have to be exact science, get approximate pieces by looking at photos.










Whoops

Re: DIY Studio 100
« Reply #9 on: September 13, 2017, 11:03:53 PM »
I have probably a lot of spare parts for this speakers.

I should have tweeters, crossover pcb's, probably bitumex and foam, hex screws and the screw females that clamp into wood also.

Let me know if you need parts


rp3703

Re: DIY Studio 100
« Reply #10 on: April 20, 2019, 08:49:51 AM »
Hey Whoops,

Sorry but I never saw any of these replies that you posted almost two years ago now. I gave up on this Proac project pretty quickly. Yes, you could build a set of these for less than a real set but when it comes to resale, you would easily be able to recoup your investment with a set of real ones but with the clones you would not. Thanks for adding to the info though. Maybe someone else will benefit from it.

Squeaky

Re: DIY Studio 100
« Reply #11 on: April 20, 2019, 06:29:59 PM »
It is a funny old thing resale value and branding. I have had a pair of studio 100s years. I blew both the woofers (not unusual problem). I replaced with the OEM part. Resale value has dropped as a result.

Whoops

Re: DIY Studio 100
« Reply #12 on: April 20, 2019, 11:29:56 PM »
It is a funny old thing resale value and branding. I have had a pair of studio 100s years. I blew both the woofers (not unusual problem). I replaced with the OEM part. Resale value has dropped as a result.

Stencil it, it's simple and easy