[Bob in St. Louis]

I hate to ask twice, as I don't mean to hound you, but have you tried them nearfield OB?

[Danny Richie]

I hate to ask twice, as I don't mean to hound you, but have you tried them nearfield OB?

I tested one in an open baffle, and it measured really well. It obviously needs something to handle the bottom end though. I didn't see any need to put together a pair of them to listen to at this point. From what I heard of the pair in the ported boxes and from my measurements on them I see no reason why they wouldn't be great in that application. But a speaker system needs to be designed around them. You can't just put a pair of drivers on a baffle and call it good.

[Bob in St. Louis]

I tested one in an open baffle, and it measured really well....

First off, thank you for the reply Danny.

Secondly, I wasn't going to ask for OB measurements, but since you brought up the word, how low do they go with a reasonable baffle?
85Hz at 85db at 2'?
That's enough "full range" for me, as I'm not looking to jam, impress my friends, or need a tactile thump in my chest.

I'm looking for just what the thread title says, "Desktop - Full Range - High Quality", that's what attracted me. I am not interested in bass for this system. This system will consist of a tablet or PC as the source, an amp that would "hide" well on my desk, and the speakers. If I want bass, I'll fire up the nine 15" drivers I have in my main system  with a few thousand watts to drive them. So suffice it to say that I do not want to design a speaker system, and 'yes', I actually do want do put them on a baffle and call them good.

Now, that being said, I am thinking about a speaker "unit" that would hang and be supported by my 20" monitor. That way, if I tilt or rotate the monitor, the drivers and baffles will move with it. Exactly like the old school monitor speakers were "back in the day". This will also avoid taking up even a single speck of real estate on my PC desk. This alone will help the shared "baffle" be almost two feet wide, which has obvious benefits for bass, yet still produce the magic of OB.

I'm going for quality in sound, and simplicity. Nothing more. "Simplicity" to the extent that I don't even want to call this a "system", if you catch my drift.

Are we on the same page? 
Bob

[Danny Richie]

Secondly, I wasn't going to ask for OB measurements, but since you brought up the word, how low do they go with a reasonable baffle? 85Hz at 85db at 2'? That's enough "full range" for me, as I'm not looking to jam, impress my friends, or need a tactile thump in my chest.

Bob, this measurement was posted on the first page.



It was about a 12" tall baffle with about about a 8" deep wing on one side. The baffle itself was 4.75" wide. You'd have to cross it to another driver in the 350Hz range. And since you wouldn't ever want to split the mid-range into dissimilar divers with different offsets causing a big phase shift in a critical range... Then you'd need to cross them to more of the same type of drivers. And it would take 9 of them in a series parallel configuration to cover the lower range only and match the sensitivity and impedance. So it would take a good 10 driver tower to work well in an open baffle.

I'm looking for just what the thread title says, "Desktop - Full Range - High Quality", that's what attracted me. I am not interested in bass for this system. This system will consist of a tablet or PC as the source, an amp that would "hide" well on my desk, and the speakers. If I want bass, I'll fire up the nine 15" drivers I have in my main system  with a few thousand watts to drive them. So suffice it to say that I do not want to design a speaker system, and 'yes', I actually do want do put them on a baffle and call them good.

It will take much more than a baffle and that;s true with just about any OB driver.

Now, that being said, I am thinking about a speaker "unit" that would hang and be supported by my 20" monitor.

A pair of these little boxed speakers problem weigh twice what your monitor does.

That way, if I tilt or rotate the monitor, the drivers and baffles will move with it. Exactly like the old school monitor speakers were "back in the day". This will also avoid taking up even a single speck of real estate on my PC desk. This alone will help the shared "baffle" be almost two feet wide, which has obvious benefits for bass, yet still produce the magic of OB.

The surface reflections of the screen would actually have a very adverse effect on the response.

I'm going for quality in sound, and simplicity. Nothing more. "Simplicity" to the extent that I don't even want to call this a "system", if you catch my drift.

If only it were that easy.

[Bob in St. Louis]

Well crap.
I see that you haven't managed to design that free lunch that all OB owners want. 
(joke <wink>)

Ok then. I missed the part about the page one graph where you said that was OB.
No problem. My bad.

I'm still in, and still have my credit card in hand.
Looks like I'll be building a damn box whether I like it or not. The real estate on my PC desk is very scarce, and very valuable.
But the $20 PC Altecs sound like hot steaming dog poop, so I'm ready for the next step. This looks like it.

Let's roll Danny. Bring it on.

Bob

p.s. Surface reflections from a monitor are unavoidable, since this is a.... desk. top. speaker.
Again... you haven't given us the free lunch we're asking for.   

[Peter J]

But the $20 PC Altecs sound like hot steaming dog poop, so I'm ready for the next step. This looks like it.

Hmmm, I would think the smell most prominent...

 

[Bob in St. Louis]

Indeed. From day one.... 
After suffering for too long, I decided to take my hole saw to the plastic cabinets to "free the sound".
Seemed like a good idea, letting the twin two inch drivers have some room to breathe....right?

But after drilling a 1.5" hole in the back, I discover that one of those 2" drivers is a passive radiator. 
Whoops. Bad move.
What now? 

After stuffing the plastic cabinets with some poly fill, and covering the hole with packing tape, I can honestly say that these $20 speakers now sound like $25 speakers.

yea....it's like that. 

If these GR Research speakers end up doing the trick, I'll let these modded Altecs go for the mere cost of shipping.
When was the last time you heard that you could get a modded set of Altecs for free? 

Bob

[mlundy57]

I see the applications for these going way beyond the desk top. I think these are going to be great for small theater systems, sound bars for TV's, and stand alone sub/sat systems for small rooms.

While I definitely want at least two pairs of the desktop speakers, a stand alone small sub/sat or sound bar/sub system is exactly what I need for my stepdaughter.  She rents a room in a house with kitchen privileges so the one room is all she really has for her things.  I was going to build her a pair of X-LS Encores but they are really a bit large for her space so she could never have an X-series theater system.

Danny, what type/size sub would you envision as a match for this type of speakers?

Mike

[Todd Willhoit]

I see the applications for these going way beyond the desk top. I think these are going to be great for small theater systems, sound bars for TV's, and stand alone sub/sat systems for small rooms.

Wouldn't the screen reflections from a TV produce the same adverse effect that you described for Bob's PC application?

Todd

[ttan98]

Hi Fellows,

I am not sure someone has already asked this question, the 7Khz dip of 5dB, I am a little concern about it, any comments anyone?

[corndog71]

Hey Danny, 

Have you considered a bipolar version?

  Just reread this thread and saw that you did try that.

[Danny Richie]

Hi Fellows,

I am not sure someone has already asked this question, the 7Khz dip of 5dB, I am a little concern about it, any comments anyone?

first of all it is only down 2.5db from the average and secondly, it is not there in the off axis. That's pretty minor. And it is one of the smoothest full range drivers that I have ever measured.

[oz_audio_todd]

first of all it is only down 2.5db from the average and secondly, it is not there in the off axis. That's pretty minor. And it is one of the smoothest full range drivers that I have ever measured.

Would it be worth using one of those cap & resistor network thingys to pad the response from 7k by 3 dB or so?

[S Clark]

You can get most of that 3dB by simply moving the speaker 10 degrees off axis and easier than a network.

[Danny Richie]

Would it be worth using one of those cap & resistor network thingys to pad the response from 7k by 3 dB or so?

Scott is correct. Just turn it 10 degrees off axis and it will be pretty flat.

See the Orange line:



And there is actually very little information up there. It is just extreme overtones. It is not the area associated with brightness.

And oh yeah, +/-1db to 5kHz! Even at 10 and 20 degrees off axis it is still almost within +/-1db to 5kHz. That is pretty impressive for any speaker.

[oz_audio_todd]

And oh yeah, +/-1db to 5kHz! Even at 10 and 20 degrees off axis it is still almost within +/-1db to 5kHz. That is pretty impressive for any speaker.
[/quote]

Oh yeah, definately cant argue with that  , how low does the +/- 1dB envelope go BTW? (for ported and sealed?)(I am assuming you can actually measure that low, your graphs always start at 200 (?)).

[Danny Richie]

Oh yeah, definately cant argue with that  , how low does the +/- 1dB envelope go BTW? (for ported and sealed?)(I am assuming you can actually measure that low, your graphs always start at 200 (?)).

The way this test box is tuned I get a slight left in the lower range and a -3db of 82Hz be the measurements. In a slightly larger box with lower tuning they will produce a more flat lower range that hits a -3db of 68.7Hz.

[Danny Richie]

Okay, I finished up the boxes and have them playing now.

Here are a few pics as they went together.



I laid some strips of No Rez down each side as it went together. I had to cut it back on the end where the driver mounts, but I left the damper on it. I also made a few passes through my table saw with the lower pieces and cut away just a slight amount of foam to leave room for the port to slide in.



I just glued it up and clamped it with some cheap clamps from Harbor Freight tools.

Here is a pic with the side glued up.



I did move the port to the rear on these and that worked out really well. I also rounded off the corners and shot it with a little black bed spray liner.

This pic shows a small compensation filter mounted on the rear wall that compensates for the baffle step loss.



Completed, front view.



And the rear view showing the ports and tube connectors.



And those cabinets are rock hard.

They have been burning in for a while now and sounding really good. With an inline RCA filter on them, and a lower section of a pair of Serenity Acoustics Super-7's right behind them, They are sounding very full range. Bass response has a limited SPL level as one would expect, but all else is great. These will eat up a lot of good two way small monitors everywhere but in the lowest ranges. Imaging is great and the vocal range is really great.

I like'em!

[Bob in St. Louis]

I'm ready now. 

[BK_856er]

Want.

BK