When I was a kid in the 70s, I decided I could build better speakers than I could afford to buy. So I designed a pair of 2 way TLS with 10 inch Radio Shack Woofer (the best I could afford at the time) and the best RS tweeters I could afford. I must have been 13 or 14 at the time. Why did I choose TLS? Because I had a small bedroom and the speakers had to fit in the wall shelving, and from what I had read at the time, TLS would best achieve the goal I had.
I built them, and they sounded way better than they looked. Remember, I was 13 or 14 at the time. The wood I used was left over plywood from my dad building our house.
So I have dreamed of designing and building a new set of speakers ever since. I recently came across a pair of DIY speaker cabinets and a Phase Linear PL400 power amp. The cabinets were a bonus, and I had no idea what I would find inside them. It turns out, they are 2 Electro Voice SP15A, and a pair of Electro Voice ST350A Neckless Radial Horn tweeters. I have a pair of Electro Voice VMR midrange on their way.
So basically, I want to base this speaker system on the Electro Voice Interface D speakers, but instead of using a 12 inch woofer, I want to use the SP15A, a 15 inch driver, and a DSP (at least initially).
I'm thinking of following the exterior design of the Interface D, but I want to use a larger TLS cabinet with the driver facing out, and the TLS port coming out the front bottom similar to Cornwalls. I already have a pair of Cornwall 1s which I love. These speakers will go into the critical listening system in the basement, hopefully displacing my Kef 105s and my Sony G7s.
Once I get the initial design ironed out, I intend to have two furniture grade cabinets made for the final version. I like big speakers and I love the feeling you get in your chest when you get the lows. The Cornwalls do this best in my house.
So, I'm looking for advice, what ever it might be. Am I crazy, is this idea viable, what size of cabinet should I use for the TLS? I'm thinking I will build the initial design using two cabinets. One for the bass bins and one for the mids and highs. This will allow me to easily adjust the Mid/high bins by moving them forward or back to help with time alignment.
Here is a picture of the SP15A and ST350As.
Does anyone have any recommendations for the eventual crossover? Advice on my approach, or choice of drivers? Anything to help. This is going to be a long project.
I built them, and they sounded way better than they looked. Remember, I was 13 or 14 at the time. The wood I used was left over plywood from my dad building our house.
So I have dreamed of designing and building a new set of speakers ever since. I recently came across a pair of DIY speaker cabinets and a Phase Linear PL400 power amp. The cabinets were a bonus, and I had no idea what I would find inside them. It turns out, they are 2 Electro Voice SP15A, and a pair of Electro Voice ST350A Neckless Radial Horn tweeters. I have a pair of Electro Voice VMR midrange on their way.
So basically, I want to base this speaker system on the Electro Voice Interface D speakers, but instead of using a 12 inch woofer, I want to use the SP15A, a 15 inch driver, and a DSP (at least initially).
I'm thinking of following the exterior design of the Interface D, but I want to use a larger TLS cabinet with the driver facing out, and the TLS port coming out the front bottom similar to Cornwalls. I already have a pair of Cornwall 1s which I love. These speakers will go into the critical listening system in the basement, hopefully displacing my Kef 105s and my Sony G7s.
Once I get the initial design ironed out, I intend to have two furniture grade cabinets made for the final version. I like big speakers and I love the feeling you get in your chest when you get the lows. The Cornwalls do this best in my house.
So, I'm looking for advice, what ever it might be. Am I crazy, is this idea viable, what size of cabinet should I use for the TLS? I'm thinking I will build the initial design using two cabinets. One for the bass bins and one for the mids and highs. This will allow me to easily adjust the Mid/high bins by moving them forward or back to help with time alignment.
Here is a picture of the SP15A and ST350As.
Does anyone have any recommendations for the eventual crossover? Advice on my approach, or choice of drivers? Anything to help. This is going to be a long project.
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Short on time, but are you familiar with this doc, re cab size, etc.? https://products.electrovoice.com/binary/SP8C, 12C, 15A EDS.pdf
I just came across the following.
rebuilding an Electro Voice Interface D into 5.1
Very impressive! It has me rethinking things.
rebuilding an Electro Voice Interface D into 5.1
Very impressive! It has me rethinking things.
Just off the top of my head, but the impression I am getting about the Interface D design is it is a simple ported enclosure with the port and the driver facing downward.
What do you think the impact would be if I change the interior so that instead of a simple port, it is a transmission line port? I have the choice of facing them both downward, or driver facing down and TL port facing forward at the bottom?
What do you think the impact would be if I change the interior so that instead of a simple port, it is a transmission line port? I have the choice of facing them both downward, or driver facing down and TL port facing forward at the bottom?
IIRC SP15A of the 1970's had a qts spec of "0.45" and far too high from the magic 0.312 qts used for 6th order alignment. My set of SP15A appeared to be based upon a "6ohm driver spec" and DCR about 4 ohm with qes raised by a 2 ohm resistor hidden from sight under a frame spoke. Without that series resistor I think Qts was closer to say an EV15L spec and well under 0.3
Look under the basket spokes and see if there's a series resistor. If so, read its spec or measure it.
Also, if you speak to a competent reconer, ask if a 15L or 15B recone kit will drop into SP15A's basket.
SP15's fullrange ferrite ancestor, I was told, was used at Sun Studios in their Karlson cabinets rather than the coaxial 15TRX. It has a softer - "prettier" midrange to my ears - maybe it had a paper coil former ? - maybe it was an effect from its presence control ??
Look under the basket spokes and see if there's a series resistor. If so, read its spec or measure it.
Also, if you speak to a competent reconer, ask if a 15L or 15B recone kit will drop into SP15A's basket.
SP15's fullrange ferrite ancestor, I was told, was used at Sun Studios in their Karlson cabinets rather than the coaxial 15TRX. It has a softer - "prettier" midrange to my ears - maybe it had a paper coil former ? - maybe it was an effect from its presence control ??
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Thank you freddi!
I was wondering how the different drivers might work with that configuration. However, reconing these woofers would defeat my secondary goal of keeping prices down and using as much parts as I already have on hand. I think it will be expensive enough for the materials, provided I can get them. I'll look further into that. I'm thinking I may not emulate the bass part of the Interface D. I really want to try a transmission line for that section.
I was wondering how the different drivers might work with that configuration. However, reconing these woofers would defeat my secondary goal of keeping prices down and using as much parts as I already have on hand. I think it will be expensive enough for the materials, provided I can get them. I'll look further into that. I'm thinking I may not emulate the bass part of the Interface D. I really want to try a transmission line for that section.
A TL will be LARGE.
Sims of reflex showed 250-400 litre suitable range, i’d expect a proper TL to be larger… 20 ft3ish ballpark guess.
You’d have to model the TL.
dave
Sims of reflex showed 250-400 litre suitable range, i’d expect a proper TL to be larger… 20 ft3ish ballpark guess.
You’d have to model the TL.
dave
Fun stuff!
I certainly hope it isn't that large. I thought a Transmission Line speaker allows you to get deeper bass without increasing the cabinet size?
I'm thinking of my Cornwalls, which have 15 inch woofers. When I did a ratio comparison between the Interface D at 1.25 times, the 15 inch woofer Interface D is about the size of the Cornwalls. And Cornwalls are very simple Bass Reflex cabinets. So in theory, if I turn the bass section into a Transmission Line, and it has the same volume as the Cornwalls, the bass should be deeper. Or am I missing something?
I certainly hope it isn't that large. I thought a Transmission Line speaker allows you to get deeper bass without increasing the cabinet size?
I'm thinking of my Cornwalls, which have 15 inch woofers. When I did a ratio comparison between the Interface D at 1.25 times, the 15 inch woofer Interface D is about the size of the Cornwalls. And Cornwalls are very simple Bass Reflex cabinets. So in theory, if I turn the bass section into a Transmission Line, and it has the same volume as the Cornwalls, the bass should be deeper. Or am I missing something?
No, in general, a TL requires 4-10x Vas depending on the driver's specs whereas a proper BR, i.e. one with optimum driver's specs, maxes out at Vb = Vas, Fb = Fs.
Interesting project - I also built my first diy loudspeaker in my teens (in the 80s) - mine were Maplin drivers built into corner cabinets as part of a school woodwork project. Like yours, they had to fit into the corners of a small room.
I would consider looking at mass loaded transmission line speakers. They offer a good compromise between depth of bass and cabinet size. They can be considered as a hybrid between bass reflex (ported) and transmission line, but are simpler to build that TL.
However I don’t know the driver parameters that suit these designs. Others may be able to help.
I would consider looking at mass loaded transmission line speakers. They offer a good compromise between depth of bass and cabinet size. They can be considered as a hybrid between bass reflex (ported) and transmission line, but are simpler to build that TL.
However I don’t know the driver parameters that suit these designs. Others may be able to help.
Some says than if a StratoCaster is not playbacked with an EV 12" then it's not a StratoCaster anymore* + **
* : No, I am not Sir McCartney ! 😎
** : member of the Castors Organisation for 12" EV guitar driver in saloon Loudspeakers 😀
* : No, I am not Sir McCartney ! 😎
** : member of the Castors Organisation for 12" EV guitar driver in saloon Loudspeakers 😀
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Interesting! I'll do some research on that. Thanks AntM!
I ordered a pair of EV Interface B EQs for this project on Tuesday. They arrived today! My understanding is that I will need to change the 4 resistors to make them equivalent to Interface D EQs.
Next, I need to find or build a pair of Interface D crossovers. Anyone have any schematics on the Interface D crossovers?
VMRs are still in transit from the US. Once I have them, I just need to get the cabinets designed and built!
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LOL, too funny. I wasn't thinking clearly when I ordered the Interface B EQs or I would have only ordered one. Well, at least I have a spare.
VMRs and crossover
I received the 2 VMRs yesterday, and the impedance looks good on both at 5.7 ohms each.
And today, I was provided the Interface D crossover schematic from a member of AK. Thanks! Here is a picture of the VMRs and a copy of the schematic for anyone who needs it.
View attachment Filter Interface D.pdf
I received the 2 VMRs yesterday, and the impedance looks good on both at 5.7 ohms each.
And today, I was provided the Interface D crossover schematic from a member of AK. Thanks! Here is a picture of the VMRs and a copy of the schematic for anyone who needs it.
View attachment Filter Interface D.pdf