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 Post subject: Emerson speakers
PostPosted: Jan Sat 06, 2018 10:49 pm 
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Location: Warner Robins, GA
I recently purchased the speakers from an Emerson console.

One 15" Jensen P15S woofer

Three cone tweeters with an EIA code of 180.

Measuring the impedance with the Dayton Audio DATS speaker tester I get 5.389 ohms for the woofer, 6.325 ohms for the tweeters (series connected) and a total impedance of 5.7 ohms with the tweeters connected to the woofer through a 4uF cap.

The cap was bad, but I had one I could use temporarily just to test the speakers.

I first connected them to the DATS and set it as the default sound device so I could play music through it to drive the speakers.

That worked decently, but wasn't very loud and the speakers sounded ok.

I then decided to figure the crossover frequency and it is 6,284 Hz. The woofer amazingly enough could play that high and sound good doing it.

I then made a 136.6uH inductor and put it in series with the woofer. The sound improved somewhat.

Wanting more loudness I connected the DATS to the line input of my AKAI Terecorder and set it to record. I then plugged the speakers into the speaker out jack of the Terecorder.

The speakers sound quite nice.



My intention was to use the woofer with my Philco 118 cathedral putting the woofer in a proper open back box and make a crossover around 200Hz since the original speaker has one piece torn on the spider. That way the original speaker can be used for frequencies above 200Hz where the cone won't move much at all saving me from having to get it repaired and I will have the typical console radio bass response.

BUT

The speakers sound so good as is that I am seriously contemplating looking for another set, building two boxes, finding a couple AKAI tube amps and using them to drive the speakers as I'm probably not even pushing a watt through the speakers and they sound plenty loud enough. Also if I did that I would make the cabinets tall enough to where I can mount one amp in each cabinet on the front above the tweeters.

I could use any SEP 6BQ5 amp, but I like the looks of the AKAI amps with the VU meter.

The woofer sounds pretty good in free air so I can only imagine it will sound much better in a proper cabinet far as bass response goes.

I'm tempted to find a cardboard box to temporarily install the speakers in just to see how they sound with some kind of enclosure.


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 Post subject: Re: Emerson speakers
PostPosted: Jan Sat 06, 2018 10:58 pm 
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Posts: 1349
Congratulations on your speaker project! :)

You didn't ask, but I just thought I'd volunteer...

I found this book particularly informative and easy to understand...

https://www.amazon.com/Speaker-Building-201-Ray-Alden/dp/1882580451/ref=pd_sim_14_3?_encoding=UTF8&pd_rd_i=1882580451&pd_rd_r=Y9MKKE483M236AHDVBNH&pd_rd_w=veVyX&pd_rd_wg=R4NmS&psc=1&refRID=Y9MKKE483M236AHDVBNH


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 Post subject: Re: Emerson speakers
PostPosted: Jan Sun 07, 2018 1:11 am 
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Thanks.

I'll look that book up.

Always appreciate more information.


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 Post subject: Re: Emerson speakers
PostPosted: Jan Mon 08, 2018 3:46 pm 
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I installed the speakers in a cardboard box, but have yet to test them.

What I might do is this.

If the speakers sound good enough I may have a box built for them and wire in two jacks and a switch on the back of one where one jack has a choke in series to form a low pass and the other jack has no choke for full frequency response.

That way I can use the one with the Philco 118 radio and should I find another set of the Emerson speakers I can build another box like the first and use both on a stereo amp. Then I can switch the one to the Philco when I want to use it and to the stereo amp when I want to use that.

All depends on how the Philco sounds through the 15" Jensen. If it sounds good enough I may just disconnect the internal speaker's voice coil and use the Jensen. The ides was to use the original speaker to reproduce what frequencies it can without causing the cone to move, but perhaps just using the Jensen is the easier way.


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 Post subject: Re: Emerson speakers
PostPosted: Jan Tue 09, 2018 1:47 pm 
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Tested the speakers last night using one channel of a FiiO A1 14 WPC amp with both stereo channels from my phone bridged together with a 220 ohm resistor each.

Amazed is not near enough to describe the feeling I had when I heard the tunes come pouring out of the speakers.

Everything I played seemed to sound excellent on those speakers granted the bass was a little lacking due to the cardboard box, but the bass was there nonetheless.

From tests I've done these speakers should easily hit 40Hz if not lower.

I did notice that on some stuff the upper midrange sounded a little harsh, but I'm not going to say it is a problem unless I hear it after installing a proper film cap and inductor which I will order on Thursday.

Will require me taking the inductor and unwinding some turns though.

Here's a couple of pictures.

Attachment:
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20180108_230548-600x800.jpg [ 99.1 KiB | Viewed 719 times ]


Looking at this picture I noticed some writing on the side of the tweeter and upon closer inspection the tweeters are Jensen.

Apparently the number with 180 in it was Emerson's part number for the speakers.

Attachment:
20180108_230817-600x800.jpg
20180108_230817-600x800.jpg [ 109.58 KiB | Viewed 719 times ]


When I have a cabinet built I do want to get the tweeters as close to the woofer as possible.

Not exactly sure if I should leave the tweeters placed horizontally like they currently are or if I should place the tweeters vertical or if I should have the tweeters placed to follow the curve of the woofer? It isn't a problem how I do the tweeters with one mono speaker, but should I find another set I will be making another one for stereo then tweeter placement will matter a whole lot more.

Here's the crossover.

Didn't know it at the time, but I found out by doing the battery test (1.5 volt D cell) that I had put the crossover components in the negative side of the speakers so that's how I drew the schematic.

Attachment:
Jensen speaker crossover.jpg
Jensen speaker crossover.jpg [ 26.77 KiB | Viewed 719 times ]


I did fix a few small tears in the woofer cone using some Elmer's glue all white school glue since it is made for paper and that's what the cone is made of.

Now once the tweeter mounting is figured out I just gotta figure out the box dimensions and what to have it built with.


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 Post subject: Re: Emerson speakers
PostPosted: May Wed 30, 2018 12:41 pm 
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So I decided to try the speaker in my smaller stereo which consists of a Lafayette LA-375 driving the main speakers driven by a 70Hz 24 dB/octave two way active crossover driven by a McIntosh C-24 preamp with a 10 watt bucket sub driven by a BASH 500 watt amp from the low pass of the 70Hz crossover.

The speaker seemed to sound quite good, although it is a good deal more efficient than the KLH 22A speakers are which presents a problem for the sub as I would need to build another one if I did decide to find another set of the Jensen speakers.


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 Post subject: Re: Emerson speakers
PostPosted: May Wed 30, 2018 10:51 pm 
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Like your cabinet. That ought to trigger a debate on what kind of box makes the best sounding enclosure. American made, Japanese made, or European. (Forget Chinese, they probably use an inferior paper pulp). I would guess that a handmade cardboard laminate, constructed with hemp fibre impregnated custom brown paper stock, might have superior response quality to the run of the mill boxes. Using glue extracted from a certain species of barnacles.


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 Post subject: Re: Emerson speakers
PostPosted: May Thu 31, 2018 1:14 am 
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Yes on certain audiophool sites that would spark a big debate.

Is only a temporary cabinet thankfully.

What I need to do is find someone who can make a cabinet and have two made for in case I find an identical set of drivers.

The plan is to get the cabinet built and for now use the Jensen with my Philco 118 radio given the internal speaker has a bad part with the spider.

Can't decide if I really want to find another set of these speakers and make them stereo though.

That would be nice as they do sound quite good even in the cardboard box.

Thing is I don't quite know how I want to do the three tweeters.

I can do them three horizontally or vertically above the woofer or in a triangle around the woofer.


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 Post subject: Re: Emerson speakers
PostPosted: Jun Sun 03, 2018 10:46 pm 
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Putting them horizontally will cause phase cancellations as you walk from side to side in front of the speaker. Stacking them vertically avoids this problem.

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 Post subject: Re: Emerson speakers
PostPosted: Jun Mon 04, 2018 11:35 am 
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Am thinking that's what I heard when testing the speakers.

Will do a vertical stack then.

Would be interesting if I had enough clearance to mount hem in a triangle in front of the woofer, but not sure how that would sound.


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