Would like to do my first speaker refurbishing or build

I got a pair of Marantz 4mkIIs. They are nothing special, just a two-way speaker with a freq. response of 50-18 kHz and a crossover level of 3.5 kHz. Their dimensions are 228mm (11-1/2'') Wide X 486mm (19-1/8'') Height X 210mm (8-1/4'') Depth

The tweeters work fine but one woofer needs refoaming, and they aren't originals (they are 2 different Rat Shack speakers).

I would like to either recap this speaker and replace the woofers, or perhaps I should just use the cabinet, drop in a new tweeter, woofer, and crossover. Which would be a better route? I'm not interested in keeping it original. Rather, I'd like to get a decent speaker out of this and learn a bit about speaker building while I'm at it.

What do you folks think?

Congrats reneborg! Your at the doorstep of a ton of fun and I hope the DIY bug bites you.

I started pretty much where you are now and I suggest you try everything you suggested. Get in there and learn. Many feel that every speaker was made with painstaking R&D and any change you make will be for the worse. I have found the opposite to be true.


Have fun

marc mc

I a different DIY bug hit me when I got my Mach Ones. The speakers worked perfectly, all drivers were ok, just the cabinets were messed up. So I refinished the cabinets. It's a lot of fun, and I enjoyed every minute of it. It was much better than just sitting at the computer and reading, I actually got to work on something on my own time and just for me.

It's definitely worth fixing up an old set of speakers that have either seen the ravages of time, or the misuse of an owner. Plus, it gives them a little bit of a sentimental value.

My 2 cents: Econo-wave:

http://audiokarma.org/forums/showthread.php?p=1856214#post1856214

The thread lays out a standard high frequency compression driver and waveguide that can be used with lots of different woofers. Lots of easy paint-by-number, connect-the-dots instructions. Big bang for the buck, a tremendous learning experience and you wind up with a great sounding pair of speakers. I've converted different 4 pairs of vintage Altec cabinets to this format - and prior to that I had never done ONE.

marc mc said:

Congrats reneborg! Your at the doorstep of a ton of fun and I hope the DIY bug bites you.

I started pretty much where you are now and I suggest you try everything you suggested. Get in there and learn. ...
marc mc

Click to expand...

Thanks marc mc! I think the bug has already bit me, as I've been fooling around a little bit with some electronics I've picked up for free or very cheap. ... as a matter of fact, I think there is some type of 'cross-contamination' because it was my quest for new to me vintage electronics that got me to buying speakers. I'm intending on learning basic skills on these, and I've already got a pair of Realsitic Optimus 5bs that are going to be my next speaker rebuild -- that is, unless I pick up something else before then

These speakers are actually part of a system I'm putting together for my 9 year old son.

Live_Wire said:

... The speakers worked perfectly, all drivers were ok, just the cabinets were messed up. So I refinished the cabinets. It's a lot of fun, and I enjoyed every minute of it. It was much better than just sitting at the computer and reading, I actually got to work on something on my own time and just for me.

It's definitely worth fixing up an old set of speakers that have either seen the ravages of time, or the misuse of an owner. Plus, it gives them a little bit of a sentimental value.

Click to expand...

These need to be refinished some too -- I have to figure that out as well. It has some chipped corners (I think it's a veneer over particle board), and I figure I'll either paint the whole thing or veneer it -- but I'd have to learn that part as well.

I definitely agree that it's worth fixing up old stuff -- I think it's fun, you learn, and sometimes save tons of $$$ while getting a better outcome. I've always been a DIYer, though my fixing up stuff has previously been cars, computers, and house stuff like plumbing, electrical, and carpentry.

ROSSO said:

My 2 cents: Econo-wave:

http://audiokarma.org/forums/showthread.php?p=1856214#post1856214

The thread lays out a standard high frequency compression driver and waveguide that can be used with lots of different woofers. Lots of easy paint-by-number, connect-the-dots instructions. Big bang for the buck, a tremendous learning experience and you wind up with a great sounding pair of speakers. I've converted different 4 pairs of vintage Altec cabinets to this format - and prior to that I had never done ONE.

Click to expand...

Thanks Rosso!

I was hoping to do something with the great body of information/knowledge there, but, frankly, I have been overwhelmed. It's not that the technical info is too over my head -- I can learn -- it's just that I don't know where to begin for my purpose; that is, I've got a cabinet, and I'm trying to figure out what drivers and crossover to use. Specifically, I go to the parts list and don't see where are the low-frequency drivers. Any guidance? I think what I need is for someone to point me to the place where I can figure out how to match components to the cabinet I have.

Maybe my knowledge is too basic to get this all, but I thought that I would pick a driver combo to work in the cubic volume of what my cabinet is and also need to match the drivers to a crossover. So the part I don't get is where do I figure out which woofer to go with, for example, this driver or any other one I like.

I did a little more hunting around in these cabinets, and figured out that:

1) the current 'crossover' is super simple. I say this because it looks like the input to the speaker terminal goes full range to low frequency driver while the other branch goes to a cap and resistor(?) and then to the tweeter.

2) the wiring is like this:


Speaker Terminal --> branch one --> woofer + -- (doesn't this make this operate as a 'full-frequency' driver?)

Speaker Terminal --> branch two --> Electro-Cap 1.70uf +-10% 100v-F3074 386-1029
Electro-cap --> ?resistor? 428-1103 1ohm 10% 5W
Resistor --> Tweeter + --


So, based on the tiny bit I know, doesn't it seem like I should replace this crossover, and get a high and low frequency driver to match the new crossover?

Thank you all for your suggestions and time!

reneborg said:

Thanks Rosso!

I was hoping to do something with the great body of information/knowledge there, but, frankly, I have been overwhelmed. It's not that the technical info is too over my head -- I can learn -- it's just that I don't know where to begin for my purpose; that is, I've got a cabinet, and I'm trying to figure out what drivers and crossover to use. Specifically, I go to the parts list and don't see where are the low-frequency drivers. Any guidance? I think what I need is for someone to point me to the place where I can figure out how to match components to the cabinet I have.
2) the wiring is like this:


Speaker Terminal --> branch one --> woofer + -- (doesn't this make this operate as a 'full-frequency' driver?)

Speaker Terminal --> branch two --> Electro-Cap 1.70uf +-10% 100v-F3074 386-1029
Electro-cap --> ?resistor? 428-1103 1ohm 10% 5W
Resistor --> Tweeter + --


So, based on the tiny bit I know, doesn't it seem like I should replace this crossover, and get a high and low frequency driver to match the new crossover?

Thank you all for your suggestions and time!

Click to expand...

The low frequency driver selection is open to either what you have, or one of several inexpensive new drivers. The Classic Series woofers from Parts Express get used a lot. If you have an interest, post a proposal in that thread - you'll get lots of help. Curiosity is the only prerequisite. The path is well worn and there is a light in the window.

You won't need any of the old crossover parts if you e-wave, you'll start with new. Looks like your cabinet width will restrict you to the 6"x6" "mini" waveguide.

Design concept: An inexpensive ($188/pair) pre-engineered compression driver/waveguide/crossover high frequency section suitable for mating with various woofers to facilitate building DIY two-way speaker systems.

Compression Driver: Selenium D220Ti, thread-on version, 8 Ohms:

http://www.partsexpress.com/pe/showd...number=264-270

Waveguide: Alternate "Mini" PT waveguide for smaller projects, Part# 364914-001, 90° x 90° dispersion pattern, Flange dimensions 6" x 6", 4" D to rear of flange with driver, $6.00 each.

Order waveguides direct from JBL Pro Parts with credit card:

http://www.jblproservice.com/forms/parts_order1.html

Rene,

Welcome to the addiction!

I, too, would suggest the E-wave conversion.

You will have to use a smaller waveguide then the JBL to fit inside your cabinet.

You could also just place the waveguide on the top of the speaker cabinet.

PartsExpress has a fairly handy guide to help you choose a woofer.

Woof Selection Guide

They list most of the numbers you will need. They give you rough volumes that each driver needs to be used in for both a sealed or vented cabinet.

Good luck with your project.

Thanks again everyone. I posted a query in the econowave thread as suggested. Thanks to your replies here, I also am feeling less overwhelmed! My remaining question is this: how closely does one need to match a woofer's suggested volume to the actual volume of my cabinet?

reneborg said:

Thanks again everyone. I posted a query in the econowave thread as suggested. Thanks to your replies here, I also am feeling less overwhelmed! My remaining question is this: how closely does one need to match a woofer's suggested volume to the actual volume of my cabinet?

Click to expand...

You can plug the Theile-Small parameters for a particular woofer into one of the free box modeling programs (WinISD, I think it is, I use) where the driver is not already in the database. You then manually enter the known internal volume of your box and the program will use that info to recommend either a sealed or vented enclosure and if vented, the size and length of the port. You can flatten or boost the low frequency response of the system by changing the port length, which changes the tuning of the speaker/box system. Its all much easier than it sounds. You'll get loads of help and most of the players get a real kick out of wringing $1000 of sound from a $250 collection of parts.