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AUDIO FORUMS >> D.I.Y. >> Anorexia sucks
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Message started by Rich Evans on 04/18/20 at 18:35:03

Title: Anorexia sucks
Post by Rich Evans on 04/18/20 at 18:35:03

Having a pair of speakers that are anorexic is really disappointing. You spend a fair amount of time scaling up some designs you bought to go from 6" to 8" main drivers and adding a nice ribbon tweeter, thinking the result will be magical.
Then you end up with something that has no bottom end. Depression sets in.
The parts I used are:
PRV Audio 8MR600X 8"
Dayton Audio PMPC-10 10uF 250V Precision Audio Capacitor
Dayton Audio PT2C-8 Planar Tweeter

I scaled up on the DNA plans I bought and presto. I get no bottom end.

I'm using my Zen amp and anything from mp3 to FLAC files.

Heck, I even tried my Pioneer Elite receiver.

flat, thin, no bass does not even begin to describe how disappointed I am with the sound.

For those of you who have more and better experience with speaker design and building, do you have any suggestions to find the missing bass?

Title: Re: Anorexia sucks
Post by Donnie on 04/18/20 at 18:45:36

Yeah, that sure wouldn't be the driver I would use for that speaker design. It is more of a midrange driver.

The Fs is almost 77Hz, kinda high for what you are wanting.

But working with what you already have, I would stuff the crap out of the chamber, that might help.

To really fix it buy a pair of these.

https://www.madisoundspeakerstore.com/approx-8-woofers/silver-flute-w20rc38-04-ohm-8-wool-cone/

Notice that the Fs is 31 Hz, much better for what you want.

Title: Re: Anorexia sucks
Post by Rich Evans on 04/18/20 at 20:29:41

Thanks for the guidance. I will stuff the daylights out of the chamber until the new drivers arrive. I ordered those drivers in hops that I'll finally get some bottom end.
If these work, my intention is to either wrap the cabinet with 3/4" walnut to get a good looking cabinet or to start from scratch and build new cabinets out of the 3/4 walnut. Wrapping them is going to be the faster of the two options, but will mean they are going to weigh a ton. But they will be so dead that they won't resonate.

The MDF gets me a cheaper material to work out the design and cuts so I can get something that sounds good before I get into making them look pretty. I had really high hopes because I love the sound from the ribbon tweeters, but without any bottom end, these cabinets almost got scrapped. I'm going to give them another try with the new drivers.

Title: Re: Anorexia sucks
Post by Donnie on 04/18/20 at 20:30:09

I think I would also rethink where you are crossing your tweeter over.

Your current setup crosses over at around 2000 hz, pretty dog gone low for that driver, Dayton recommends crossing it over at at least 3500 hz.

According to my calculator you need to be using around a 4 uf capacitor, but I would even go higher than that myself.

But my recommendations are based on not using the 8" driver that you are using.

http://www.learningaboutelectronics.com/Articles/High-pass-filter-calculator.php#answer1

Oops, I see that we crossed answers there.

You will be happy with he Silver Flutes, and I would still recommend changing the Cap.

Title: Re: Anorexia sucks
Post by Rich Evans on 04/18/20 at 20:34:41

and I just ordered the new caps.

Again, thank you for the guidance!

Title: Re: Anorexia sucks
Post by Rich Evans on 04/24/20 at 20:24:37

...and on the 7th day the parts arrived.

If I can ever stop listening I am going to start on the walnut exterior for these babies. THANK YOU to Donnie for your recommendations. The difference is like having finally been able to hit the all you can eat buffet.
I am going to settle in for some serious listening now that I appear to have a sound stage and the full instruments again.

and with the 2 watt Zen amp I have already been told to turn it down. *SIGH* there is a downside to everyone working from home.

Title: Re: Anorexia sucks
Post by Donnie on 04/24/20 at 22:54:36

Rich,

I'm glad that everything worked out for you. The Silver Flutes will get better and better and the tweeters crossing over higher will help the sound quite a bit.

I've slowly learned what all of those numbers that they show in the specs of speakers mean.

One big thing I noticed with the PVR's was that they didn't go very low and that they were 5 or 6 Db more efficient than the tweeter. That is noticable.

Anyway I'm glad that it sounds much better now.

Title: Re: Anorexia sucks
Post by Brian on 04/25/20 at 02:57:24

Hello Rich,
Perhaps I could not see it because of the white wool, but where does the rear wave of your 8 inch speaker enter into the horn expansion?
Is it at the back at the top of the horn passage, or is it into that upper chamber through the hole the wires are coming through? Or someplace else?

Brian

Title: Re: Anorexia sucks
Post by Donnie on 04/25/20 at 16:41:55

Rich,
Why not try veneering the cabinets?

You can get really nice results and there are a bunch of different woods to pick from.

This is who I use.

https://www.oakwoodveneer.com/wood-veneer/

Title: Re: Anorexia sucks
Post by Rich Evans on 04/25/20 at 18:57:40

I've never worked with the veneers before. Having inherited dad's collection of tools and grown up watching him, it was always solid woods and build it to last for generations. I can't say that my skills are anywhere near his (I doubt they ever will get there either) but I do love the therapy provided by hours in the garage.

Honestly, I have never even thought about building with a veneer before. It was either an MDF prototype (that usually stayed around for years) or it was furniture making with solid woods. Based on some quick clicking around, I could do full purple heart cabinet at a fraction of the price of solid walnut with a purple heart accent. *SIGH* I keep discovering how little I know by reading and typing to people smarter than I am.
Thank you for making me think this through all over again.

Title: Re: Anorexia sucks
Post by Donnie on 04/25/20 at 19:16:14

Yep, your already built MDF cabinets, a sheet of veneer and some glue is all you need to make 'em purty.

I'm never the voice of reason, kind of like the little devil that sits on your shoulder!

Title: Re: Anorexia sucks
Post by Archie on 04/25/20 at 19:44:03

I'm anti MDF so I think you ought to build them out of solid wood -- NOT overlayed on MDF. The latter could cause issues if the wood expands and contracts with humidity while the MDF doesn't.

Title: Re: Anorexia sucks
Post by 4krow on 04/29/20 at 07:13:17

Just read this thread, and the beginning just didn't make sense... until the driver being used was discussed. I had planned on trying out 3 different drivers, the Silver Flutes being the third driver to try out. I never made it past the second driver, which is the Mark Audio 12P. I first tried the Audio Nirvana 8" classic, and as the opposite of your experience there was way too much bass, and it was boomy. I don't even remember the midrange or treble. After about a day or two, that driver had to come out. The 12P is stunning even today after break in. I mean it sounded better than almost anything that I ever heard right out of the box. Now that the weather is agreeable, I will have the chance to finish up the cabinets and hear even better bass, since the cabinets will have an additional 3/4" layer of ply that has been damped with Acousti-coat from Parts Express. The cabinet is made of 3/4" MDF, and the ply will be bonded over that.

Title: Re: Anorexia sucks
Post by Rich Evans on 04/29/20 at 13:23:47

Brian - the rear wave enters the back chamber through the hole at the top where the wires are coming through. I am much happier with the sound quality after following Donnie's recommendations on both the silver flutes and the x-over point.

I still need to do the cabinet thing and make them pretty. But I might just listen tot them for a while first.I still have the plans for the NFX and those also take an 8" driver. My limitation is the square footage in the house. I don't have anywhere to put all these toys.

Title: Re: Anorexia sucks
Post by Brian on 05/03/20 at 01:43:53

I thank you, Rich for the information.
A comparison to the NFX sounds like a lot of fun! I think I remember that they can go close to the back wall, so they save space.

Best wishes for whatever you decide to do.
Brian

Title: Re: Anorexia sucks
Post by Rich Evans on 05/11/20 at 00:40:36

I got sidetracked making a pair of the tiny radials. That was an excellent side-trip by the way. I encourage everyone to get the plans if you are a wood worker or wait until Steve starts selling the completed versions. Those things are unreal.

Meanwhile, I'll have to see if I can sneak another pair of the 8" Silver Flutes so I can do a reasonable comparison. I'd like to try playing around with the different choices Steve offers on plans. Then if I every settle on something, I'll make decent cabinets.

Or perhaps I should just stick with the DNA2 cabinet design, make them properly, so can be proud of them and call it quits for a while. Listen to those until I get bored and then make the NFX cabinets. This is the problem with all those plans Steve makes available. Too many choices.