Put your money where your mouth is. Building a good 8" speaker.

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My nephew Nick phoned me up the other day. Said he needed some speakers for his amp and CD player. Thankyou, Nick, I need to clear some space in system7 labs. :D

I had to rustle something up for him. So I dug out my old modified Sony E44 speakers. These originally had a totally useless mere 3.3 uF HP filter on the Sony mylar cone tweeter. That was it! :eek:

Great lively and near 90db efficient retro high Qms Eminence Alpha 8A type woofer with corrugated surround and almost no dustcap, and a new mylar tweeter.

I had a Visaton DT94-8 Mylar Dome lying about along with some old crossover from a previous experiment.

Just needed the 6.8R tweeter resistor brightening up 2dB to 4.7R for a good sound. FWIW, this a Butterworth3 filter with all the good dispersion (due to a 90 degree phase difference) in all directions that that brings. Really, I wonder why you folks obsess about LR2 and LR4.

FWIW, you often see 3:1 ratio 3.3uF/0.3mH/10uF BW3 tweeter filters. But the science says that with a 6R series resistor in front, the capacitors tend to equality and the coil gets smaller.

The bass filter really just does a bit of response shaping and rolls off the nasty cone breakup above 3kHz a bit, nothing drastic, not even any significant bafflestep required. A bit of guesswork involved, because I have no idea how a Sony E44 bass compares to a Visaton W200S-8, but it sounds alright and looks similar. Like Troels' bass filter here:
TQWT-

Mylar domes tend to a rising brightness, so a 7.5R and 1.5uF Zobel tames them, and allows you to adjust tweeter level easily via the resistor in front of the tweeter filter. Every ohm changes level by 1dB.

All in all, I am not ashamed of this speaker. In fact I shall miss them. :cool:
 

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I'm curious why there are not more designs out with Eminence, they spew out 10,000 speakers a day and where do they all go???

Eminence is the world's #1 loudspeaker manufacturer | Eminence Speaker

Good question. And to be honest, ten thousand drivers a day is a very impressive figure.

And even if most Eminence drivers are your run of the mill everyday PA stuff that doesn't look that impressive on the surface, for the price they ask for them you can make some seriously nice loudspeakers out of them.

Here in Europe brands like Peerless, Vifa, Visaton and SEAS are ubiquitous both in DIY and commercial designs. But not a long time ago a local Finnish internet audio publication hosted at audiovideo.fi made a series of design proposals for Eminence's coaxial drivers. They tried all of them, from 8" to 12". I don't know if the two smaller ones were really worth mentioning, but I've heard the 12" version, and it's really good for the price. And the thing is, no-one who's built it has complained. On the opposite, high praise has been sung for the lowly Beta 12CX and APT-50.
 
Seems like you have a slight time alignment / phase issue between the two drivers? They aren't summing to +3dB at your XO point. The power response might not droop so hard around 2kHz once you get that fixed too.
As I said, this was a quick hack of a crossover I built way back. I have forgotten what it was actually designed for. It's quite a good BW3 IMO. 90 degrees from 500-5000Hz, with the usual 3kHz phase horror of a 8" speaker which just happens to be the crossover frequency and allows me to invert tweeter polarity. Because they ALL have some anomaly of Frequency response and phase there. Just like 6" bass goes wrong around 5kHz.

I thought the power response was rather good actually. BW3 sounds very natural away from the ideal listening position for that reason. It's all about the high Qms, IMO. The PA-type Sony driver probably peaks a bit more that the Visaton, but I tuned it by ear.

Smaller ferrite bass coils sound way better than big ones IMO. A 1.5mH would kill the lively sound IMO. I model time-aligned a lot, phase and frequency response and power delivery, and I always find that you can only get two of the three flat. Dispersion and impulse response may be players too. Is there some law of nature at work? I don't know. :confused:

I do want to have a go at Eminence type drivers. A lot of people razor off the dustcaps, because they sing their own tunes as someone said. That and my favourite cone tweeters.
Monacor HT22-8
Monacor SPP-90

But hey, enough about me. What have YOU built in the 8" range. :)
 
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Looks like a good 8". How did you get the 2k dip to fill above and below? Is this simmed, close measurement distance?

I'd say don't slice off a dustcap for no good reason. Try it with a driver you know but may not need. I found that older style spice containers made with a cardboard tube and a steel lower rim are easy to fit in the dust caps place.
 
Bumping an old thread here, but I was doing a bit of a redux on these speakers for various reasons to do with retro sort of designs a la Wharfedale and Gilbert Briggs. And many of my old friends in this thread still hang around here, so might be interested. :)

497756d1439090970-money-mouth-building-8-speaker-sony-e44-modified-jpg


One of the things we know about a good 90 degree Butterworth design is it works in either polarity. IIRC, there is less group delay where the tweeter phase is in advance of the woofer phase.

So I was playing these with negative polarity on the Visaton DT94/8 mylar tweeter, but thought I'd swap to positive polarity and have a listen. Very nice indeed. Seems to flatten the power response, which you can hear on Miles Davis' outstanding jazz record "Kinda Blue", though bear in mind I am winging it a bit by using a different bass in the modelling.

I have found out a little more about that lovely retro Sony bass too. Small 1" voicecoil. Transparent cloth dustcap. Cloth surround. And a metal former, to my surprise. But my definition of easy to work with and musical. :cool:
 

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