My frugal reference loudspeaker with Philips Fullrange.

[t.antony]

...How much time did each take you?

I think the first one had taken about 1.5 hours as I had to unwind multiple times to get a proper lay of windings above one another - but still they are a bit off, probably my winding skills will improve over time. The second one might have been quicker by 20 minutes.

Regds.

 

[Thad E Ginathom]

Don't take this the wrong way...

At first, I thought that photo was coils of wire as you had bought it --- because it looks so neat!

Now I realise this is the finished coil. You certainly have a lot of patience.

 

[t.antony]

Don't take this the wrong way...

At first, I thought that photo was coils of wire as you had bought it --- because it looks so neat!

Now I realise this is the finished coil. You certainly have a lot of patience.

Yeah, this is one monotonous task that demands oodles of patience, I was a bit short of it initially which resulted in a large turnout time for my first inductor. After the initial few layers, it's very easy to loose the laying symmetry in the haste to finish the coil .

Made two more coils last night, 4 down ... 2 more to go.

Regds.

 

[anilva]

Anthony,

Congrats. Very impressive on the coils. They look bought from madisound.

You mentioned you wanted high DCR. Why? I thought you would need low DCR...BTW 1.3 ohms is a terrific figure (low in my view).

Cheers.

 

[t.antony]

Anthony,

Congrats. Very impressive on the coils. They look bought from madisound.

You mentioned you wanted high DCR. Why? I thought you would need low DCR...BTW 1.3 ohms is a terrific figure (low in my view).

Cheers.

I am planning to experiment with the following crossover options.

Plan A) Build a 2 way xover by connecting both drivers in parallel and applying the BSC at the fullranger and a first order low-pass for the woofer at 200hz. The effective impedance of the system will come down to 4ohms in this case. My Sansui AMP is rated at 8ohms and sonically the 4ohms response is not as good as the response at 8 ohms. A high DCR inductor in the xover will act as a series resistance to the woofer and increase the overall impedance. I am aiming at 6ohms overall. If I can tweak the BSC to get an acceptable response, I will keep this system as a two way.

Plan B) If Plan A does not work well, bring in the tweeter and build a 3 way crossover with xover points at 200hz and 2.5khz respectively and apply the baffle step correction to the fullranger. The high DCR of the inductor is not good in this scenario, but since it's not very high, it should be ok to use in the circuit.

Regds...

 

[t.antony]

The first (experimental) phase of crossover is completed, I was tweaking the BSC circuit for the last four days days and finally settled on the values after extended listening tests. The current system seems to provide best balance between the lows and mids as per my preferences. Needless to say I am very satisfied with the results so far. The crossover is according to Plan A with the addition of a tweeter crossed at 2.5kHz.

Apart from the air core inductors, the crossover uses few 10w wire wound resistors and Keltron motor start capacitors. These are metalized poly propylene types (MPP). Decided to give a try after reading Rod Elliots experience of using these in crossovers. (BiAmp (Bi-Amplification - Not Quite Magic, But Close) - Part 2) also thanks to goldyrathore for giving me that link. After using these caps for the past few days, I can say they are very good indeed. These are relatively cheap and available easily with varied ranges from 5 microfarad to 150 microfarad, the only disadvantage being the huge size.

Here is a picture of the messy looking xover. I need to reassemble this to a compact size once finalized

Even though the system sounds good overall with the addition of tweeter, the dip at 2kz still remains. I need a tweeter that can be crossed slightly below 2k. Ideally that translates to a tweeter with an Fs around 700hz. The Philips tweeters I use currently have a high FS of nearly 2kHz and will not be very useful in compensating for the dip at 2khz. I need to do some more tweaking before making any conclusion about the tweeter.

Republic Day Greetings to everyone

Regds...

 

[vivekphadnis]

Hi Antony,
Very neat coils. Tell me, how did you get the windings on top of the other and then use nylon ties? did you wind them on something and remove the former later?
I use small transformer bobbins to wind them on and use the coils as they are.


Vivek

 

[sunilraj]

Bravo, am just waiting to see the pics of your complete speakers.

 

[t.antony]

...how did you get the windings on top of the other and then use nylon ties? did you wind them on something and remove the former later?

I used a pvc pipe as former and old cdroms on both sides to control the laying width in my diy winding machine. While laying one winding above a layer I had to press down the wire with a finger so that it does not skip over other windings at the same time the other hand was used to control the winding tension. It's a bit taxing on the fingertips but if there is adequate tension, the layers will not shift that easily. After completing the windings, I put masking tape around the last layer so the windings does not move. The coil is then "slipped" off the former after removing one of the cdroms and nylon ties were applied. The masking tape is removed after applying the ties.

Hope this explanation helps, good luck with your inductors.

Regds...

 

[Hari Iyer]

Winding inductors for the crossover and baffle step correction network is the next challenge. I found this DIY link which seems like a workable solution for making a cheap coil winder - DIY Hand-Driller Coil Winding Machine with Digital Counter.

Also here is another interesting DIY link for making a digital counter from a calculator. Versatile and Low Cost Digital Counter

This online calculator seems like a good option for making air-core multilayer coils. It gives the required wire length and weight as well. As I need inductors of high value (+6mH), air-core is going to be expensive and bulky, so probably I will use a laminated I-core.

Does anyone have an inductor winding chart in SWG? Also any idea where I can get laminated I core and bobbins in SP road. In my last visit, I tried couple of places including Universal Transformers but they does not seem to have them.

Please visit the site Mark 2 - Inductor Sim for an inductance simulator for your requirement. You will have to finally measure the inductance with an LCR meter to validate the calculated and measured values though.

Best of Lucks, Hari Iyer

 

[sunilraj]

I used a pvc pipe as former and old cdroms on both sides to control the laying width in my diy winding machine. While laying one winding above a layer I had to press down the wire with a finger so that it does not skip over other windings at the same time the other hand was used to control the winding tension. It's a bit taxing on the fingertips but if there is adequate tension, the layers will not shift that easily. After completing the windings, I put masking tape around the last layer so the windings does not move. The coil is then "slipped" off the former after removing one of the cdroms and nylon ties were applied. The masking tape is removed after applying the ties.

Hope this explanation helps, good luck with your inductors.

Regds...

Well, it is difficult for me to do that job. You have a sensitively crafted hands

 

[sunilraj]

The first (experimental) phase of crossover is completed, I was tweaking the BSC circuit for the last four days days and finally settled on the values after extended listening tests. The current system seems to provide best balance between the lows and mids as per my preferences. Needless to say I am very satisfied with the results so far. The crossover is according to Plan A with the addition of a tweeter crossed at 2.5kHz.

Apart from the air core inductors, the crossover uses few 10w wire wound resistors and Keltron motor start capacitors. These are metalized poly propylene types (MPP). Decided to give a try after reading Rod Elliots experience of using these in crossovers. (BiAmp (Bi-Amplification - Not Quite Magic, But Close) - Part 2) also thanks to goldyrathore for giving me that link. After using these caps for the past few days, I can say they are very good indeed. These are relatively cheap and available easily with varied ranges from 5 microfarad to 150 microfarad, the only disadvantage being the huge size.

Here is a picture of the messy looking xover. I need to reassemble this to a compact size once finalized

Even though the system sounds good overall with the addition of tweeter, the dip at 2kz still remains. I need a tweeter that can be crossed slightly below 2k. Ideally that translates to a tweeter with an Fs around 700hz. The Philips tweeters I use currently have a high FS of nearly 2kHz and will not be very useful in compensating for the dip at 2khz. I need to do some more tweaking before making any conclusion about the tweeter.

Republic Day Greetings to everyone

Regds...

So these MPP Cap available in b'lore, can you let me know the dealer?

 

[t.antony]

Please visit the site Mark 2 - Inductor Sim for an inductance simulator for your requirement. You will have to finally measure the inductance with an LCR meter to validate the calculated and measured values though.

Best of Lucks, Hari Iyer

Thanks, I used the same sim as indicated in my post.

This simulator seems to be fairly accurate, predicted the DCR correctly and when I measured inductance with my Mastech 8222H the reading flips between 5 and 6. If time permits, I will try measuring the inductance with Limp when I reassemble the crossover.

Regds...

 

[t.antony]

Well, it is difficult for me to do that job. You have a sensitively crafted hands

Thanks, IMHO you don't need any special skills, just a slow and steady approach will do. It helps if you have some soft music playing in the background as things could get quiet boring after about 300 turns ..

So these MPP Cap available in b'lore, can you let me know the dealer?

I think the shop name is Keltronix in SP road. Tibcon is another good Indian brand.

Regds..

 

[t.antony]

Took some more measurements today. The speaker positioning was tweaked for better bass response at my seat. Apart from the near-field & listening position measurements of a single channel, I had taken combined response of both channels at my seat as well(green). The speakers were toed in about 30 degrees at this time.

The lows and mids improved compared to the last time. Tweaking the BSC is indeed a good way to fine tune the mid response. But even with the addition of tweeter, the dip after 2k is very much there, I suspect it could be due to the mic preamp, need to try out with another one to make sure.

Further tweaking of the xover is planned after finishing the enclosures with fiberglass.

Regards.

 

[t.antony]

Update...

Did some experiments with tweeter location and time alignment. The co-axial tweeter placement seemed to compromise the horizontal dispersion. I had to toe-in the speakers considerably and the response beyond the sweet spot narrowed down rapidly as well. Also it seemed like those tweeters are lacking in sensitivity to compensate for the fullrange and missing finesse in the upper octaves. So I brought in the Peerless low Fs tweeter I was reserving for my OB project. After experimenting different positions atop the baffle, a location midway in X axis offseted about 1 inch from the front baffle in Z axis appeared overall best. Horizontal dispersion improved along with a bigger sound stage.

I have used a cut pipe as a crude waveguide and to smoothen out the edge diffractions. Sonically it turned out to be very satisfactory.

So I am deviating from my co-axial plan to something like this.

By going this way later I will get a chance to attach a waveguide to the tweeter which will match it's directivity to that of the 8" fullrange.

BTW this project is currently overlapping with another speaker project that is nearing completion now, I am planning to do the final finish of both together as it be more economical that way

 

[Non_Techie]

So far so good...learnt many things from your project...now with out even starting my DIY..5.1 with IWAI speakers...i can feel the experience out of this project...

Very detailed...great info for beginners like me...it will take at least 6 months from here..to get this done...Will start a similar thread...Thanks......Non_techie...

 

[t.antony]

So far so good...learnt many things from your project...now with out even starting my DIY..5.1 with IWAI speakers...i can feel the experience out of this project...

Very detailed...great info for beginners like me...it will take at least 6 months from here..to get this done...Will start a similar thread...Thanks......Non_techie...

Good to know it helped, looking forward to see your diy endeavors in here.

Here are a few sites to get more info on speaker building

AudioCircle
Home Theater Forum - Home Theater Systems - HomeTheaterShack
diyAudio
Quarter Wavelength Loudspeaker Design
Zaph|Audio
Elliott Sound Products - The Audio Pages (Main Index)
Linkwitz Lab - Loudspeaker Design

Some measurement and simulation software - most of them are free

ARTA Home
HOLM Acoustics
Home of the Edge
LinearTeam
jbagby
FRD Consortium
Loudspeaker enclosure calculating with Thiele Small parameter
UniBox - Unified Box Model for Loudspeaker Design - Kristian Ougaard

Here is how to make a simple measurement mic - you will need it, it can be used with any of the measurement software listed above.

AudioBlog: arta impedance frequency response theil small

A better measurment mic - Recording and Measurement Microphones

 

[t.antony]

Started the finishing job last weekend. Fiberglass putty is used for leveling the surface blemishes. Here is a picture after the first coat is applied.

It will need few more passes with putty and a lot off sanding and buffing to get an acceptable finish before painting. It would have been much easier if the carpenter did his job correctly . Many 90 degree cuts and edges were not accurate and it needed a lot of time finish off with putty. Next time I hire a carpenter, I will double check if they have proper tools to provide consistent output, or better still - get it done with a CNC router.

 

[grubyhalo]

Looking good there!