DIY mini everest or S2900

[vernb]

Well finally I got going. Had the drivers lying around for a looonnnggg time. Got the time and borrowed a friend of mine's wood work shop.
I started out by cheating (since this is my first DIY ever, I hope I am forgiven) and bought myself a very old pair of cabinets. They were in oak veneer and were pretty damaged. So I knocked out the baffles and sanded them down and gave them a walnut coloured tarnish.

[vernb]

The drivers you see are:
JBL H3100 horns
JBL 276ND
JBL LE-1400H and 1400PRO (I still haven't decided which one to use)
JBL 2405

[vernb]

I bought myself a kitchen table top from plantation teak, and cut out the holes. Now gluing is next

[vernb]

While waiting for the next step, I'll hurry to say thanks to especially 3LH members: Zilch, Mr Widget and Jan Daugaard for helping out and giving advices before the actual DIY phase.

[vernb]

Now I have taken a left over from the sink (walnut) and fixed on top of the baffle for the 14" woofers. I always liked the looks on "the pregnant penguin" (B&W DM6) and like the idea of sloped baffles, and this is wannabe slope....

[vernb]

As you can see, it is the 1400 PRO in there at the moment. The big blank space next to the H3100 horns are for reflex ports and the 2405 super tweeter ( I am not yet sure if I will be needing it??). I almost forgot to thank MatthiasA, who also contributed with his expertise.

[vernb]

just to show you the pregnancy. Now comes the real hard part for me. X-over time. I have most of the parts and the layout, but who knows what it will sound like.....

[macaroonie]

Nice work so far Vern they look tidy.:applaud: Be careful with that block wood baffle and central heating, it will want to swell and contract,particularly if the atmosphere is warm and dry. You would be well advised to make sure that all of the exposed area of that wood has a good coating of oil at least or varnish. Inside the cabinet and out and all the cut edges where the drivers and horn are.
I installed a kitchen island worktop about two years ago in Beech wood and under it there is one of those small wine cooler fridges. Although there is a silvered barrier above it and ventilation gaps the blocks immediately above have shrunk and split a little. The fridge is one of those catalytic jobbies to boot and does not throw out a lot of heat.
Whatcha going to do about your x/o ?

[Krunchy]

Nice Kuchnia Mac! (appypolylogins, my polish is a bit crude).
Hi Vernb!, your project is coming along quite nicely :applaud: Keep the pictures coming!

[vernb]

Here is a look at the oiled cabinet. Thanks for the advise. I would start crying and kick myself if the wood split because I had forgotten to oil them.

[vernb]

Here you see my x-over possibilities. I have an original JBL 4430 set and DIY S2600 x-over, halfway done. and a load of parts. Luckily the S3100 and S2600 share the layout. Only the mH and mF are different.

[vernb]

Since I am going to biamp, I was wondering about this:
Is it possible to just remove all resistors from the network and instead adjust the input going to each driver on the poweramps (they have attenuators)?
I really don't like the idea of dampening a driver if I don't have to. But I don't have the knowledge on x-over design to help my self.

[Robh3606]

Is it possible to just remove all resistors from the network and instead adjust the input going to each driver on the poweramps (they have attenuators)?

You have to understand what the resistor is doing there. Don't assume they are just there as pads only. The pads for the driver yes.

Rob:)

[loach71]

If you are biamping, why not use an active crossover?

[Mr. Widget]

If you are biamping, why not use an active crossover?You still need a network in there to compensate for the falling response of the bi-radial horn.


Widget

[demon]

why yes, if you are bi-amping you really should consider going fully active -this is the way to go (nowadays) if you have a little time to play. modern day studiomonitoring is all active, for some reasons.
if you are using a digital-activ crossover (for 2x2 ways youd need only one..) you can even change the delay of the chassis!
but it will take some time to understand and use the technology...i dont use it yet...

cheers anyway.
the speakers look great!!!

mikey

ps:
ill send you an interesting link via pm.

[vernb]

You still need a network in there to compensate for the falling response of the bi-radial horn.


Widget

But does that mean that, if I install the 2405 as supertweeter above 10kHz, then I don't need the resistors in the x-over to compensate for the falling response of 276ND on the H3100 horn?

[Earl K]

Hi Vern,


But does that mean that, if I install the 2405 as supertweeter above 10kHz, then I don't need the resistors in the x-over to compensate for the falling response of 276ND on the H3100 horn?

- The 276nd ( on the H3100 ) will have a falling HF response ( @ 6 db per octave ) starting at around 3K . Therefore you'll need some HF horn compensation to flatten out the response out to 10K ( even using a tweeter )
- Your crossover will need an RC bypass network to attenuate the midrange ( such as is found within the S3100 or S3100 mkII network ) .

About resistors ;
- I read an older S2600 post of yours , so I realize you've got a "bee in your bonnet" with you thinking that the top-end of the S2600 is compromised ( dull ) because ( your guess only ) too much resistive attenuation was included in the network ( though necessary to match the sensitivety of the ME120H ). There may be some truth to your conjecture / but that sort of tinkering ( sparkling up the UHF ) is best left to experienced network designers .

- ie; don't fixate about the sound of resistors, that'll only serve to grind your project to a halt . Remember , you're using different drivers than what you're used to listening to .

:)

ps ; nice project !

[vernb]

Hi Vern,

- The 276nd ( on the H3100 ) will have a falling HF response ( @ 6 db per octave ) starting at around 3K . Therefore you'll need some HF horn compensation to flatten out the response out to 10K ( even using a tweeter )
- Your crossover will need an RC bypass network to attenuate the midrange ( such as is found within the S3100 or S3100 mkII network ) .

About resistors ;
- I read an older S2600 post of yours , so I realize you've got a "bee in your bonnet" with you thinking that the top-end of the S2600 is compromised ( dull ) because ( your guess only ) too much resistive attenuation was included in the network ( though necessary to match the sensitivety of the ME120H ). There may be some truth to your conjecture / but that sort of tinkering ( sparkling up the UHF ) is best left to experienced network designers .

- ie; don't fixate about the sound of resistors, that'll only serve to grind your project to a halt . Remember , you're using different drivers than what you're used to listening to .

:)

ps ; nice project !

Thanks Earl
That was just the answer I was looking for. Now I'll keep on working on the passive x-over
Vern

[loach71]

But does that mean that, if I install the 2405 as supertweeter above 10kHz, then I don't need the resistors in the x-over to compensate for the falling response of 276ND on the H3100 horn?

Then you would be triamping....:applaud:

I gave up on the use of passive crossovers years ago. Too much time and bother to tweak them. Get a good active crossover, a good 1/3 octave EQ and an RTA with a calibrated mike. Don't buy the el-cheapo units... get something good and you will be a happy camper.

[vernb]

Yesterday morning I tried them with the 4430 crossover. Sounded awful....
I have finished the S3100 crossover now and hope to try it on the weekend.

Would you agree that the 1400PRO woofers might need to play quite a few hours before they will actually play deep bass? They got very stiff surrounds.

[Earl K]

Would you agree that the 1400PRO woofers might need to play quite a few hours before they will actually play deep bass? They got very stiff surrounds.

- What did you tune the cabinets to ?
- Have you run tuning simulations for the 2 woofer types ( for these cabinets ) ?

- Don't use the 1400PRO for this project. It's 50hz Fs is very high for a home HiFi project .
- Use the LE1400H.

- Essentially, for HiFi usage, go with the woofer that has the lowest Fs, lowest Qts, highest Vas & highest BL factor ( motor strength ) / as well as largest MMS ( within reason ) .

- As it stands right now, your cabinets are most likely too large to be able to achieve an optimal tuning for either 14" woofer . From the pics, those cabinets seem to be about 5 to 5.5 cu ft ( 142 to 156 litres ) . What is the internal volume ?

- You can always reclaim internal volume ( make it smaller ) by putting ( measured volume ) sandbags into a cabinent .

< > :)

[Earl K]

Yesterday morning I tried them with the 4430 crossover. Sounded awful....
I have finished the S3100 crossover now and hope to try it on the weekend.


- "Sounding Awful" can just about always be translated into a visual form .
- ie; those with experienced eyes can translate the curves into meaningful opinions once they see some response curves.

- Do you have any testing tools ( RTA software or hardware ) to help you make a connection between what sounds good or bad ?

<> :)

[vernb]

- "Sounding Awful" can just about always be translated into a visual form .
- ie; those with experienced eyes can translate the curves into meaningful opinions once they see some response curves.

- Do you have any testing tools ( RTA software or hardware ) to help you make a connection between what sounds good or bad ?

<> :)

Well you are right that the 1400pro is more of a midrangedriver than a hifi bass. I have taken them out and installed the LE-1400h. Haven't heard them yet though. I've been sick all weekend.
The cabinets internal volume is 115litres, deducting perhaps 15 liters for horns and drivers, it might still be 20-30 litres too much for the 1400h.

I don't have measuring equipment, so it will have to be by ear, when I get the crossovers up and running thursday or friday.
vern

[Mr. Widget]

Yesterday morning I tried them with the 4430 crossover. Sounded awful....That's refreshing. :bouncy:

So often when someone puts their money and time into a DIY project they consider it a raging success regardless of how it actually sounds. It's good to see your objectivity is intact. Armed with that and the willingness to press onward I am sure you will end up with a really great speaker system.

Keep up the good work!


Widget

[vernb]

we have a public holiday the next 5 days, so I have time to play again. I will also try a pair of Fostex supertweeters I have lying around, just to see what it does. I don't want to be cutting holes for the 2405 tweeters before I know if I actually need them.

[vernb]

Finally I got the set together with my modified DIY S3100 x-overs. At the moment I only use that x-over for the JBL 276ND drivers (crossing at 850Hz). An electronic x-over is used for the bass drivers crossing over at 720Hz 12db/octave. The 2405 supertweeters you see in there now, are not playing yet, and I dare say I wont be needing them. The sound is a lot better now and I almost can't believe how good they sound. There is still a lot of work to be done with bass response though. It is tight as.... but not deep deep, and there seems to be a hump on the curve somewhere.

It might help if I dragged my JBL S8 speakers out of the room. The Accuphase C240 and P400 seem to fit nicely. I will put on my Marantz MA-5s in a couple of hours to see what that does.

[stephane RAME]

Hello,

Very good job, the listening position it is not too low.

Stéphane :applaud:

[vernb]

shit, something wrong with my electronic crossover. It just blew my accuphase P-400, and a Nakamichi PA7 :biting:.

Finished the passive x-over for the woofers. Put on Pioneer Spec 2 for woofers and Marantz MA-22 monoamps for the horns. Very nice, but still som adjustment to do on the midbass.

[vernb]

- What did you tune the cabinets to ?
- Have you run tuning simulations for the 2 woofer types ( for these cabinets ) ?

- Don't use the 1400PRO for this project. It's 50hz Fs is very high for a home HiFi project .
- Use the LE1400H.

- Essentially, for HiFi usage, go with the woofer that has the lowest Fs, lowest Qts, highest Vas & highest BL factor ( motor strength ) / as well as largest MMS ( within reason ) .

- As it stands right now, your cabinets are most likely too large to be able to achieve an optimal tuning for either 14" woofer . From the pics, those cabinets seem to be about 5 to 5.5 cu ft ( 142 to 156 litres ) . What is the internal volume ?

< > :)

Well as measured the cabinets are approx. 100 litres when I deduct the volume taken up by the drivers. That is almost exactly 3.5 cubic feet as Greg Timbers recommends for the 1400PRO drivers.
The LE-1400H should only have 60 litres.
I have tried both of them now in the cabinet as it is and I really can't decide. The LE-1400h have more LF oomph, but the 1400PRO really kicks and sound much better in the MF region. Better dynamics and very very tight bass response.
I know I should try to put in 40liters of sandbags for the LE-1400h, but that is a lot of sand, and the speakers already weigh 65kg each.
The 2405 tweeters are out and a reflexport installed in its place.

It seems that the 276ND goes very well on the H3100 horn with S3100 x-over. I had guessed that only because 2426, 275ND and 276ND all share the same replacement diapraghm, an so shouldn't be that different drivers after all.

[Skywave-Rider]

They look fantastic!

Would the addition of more fiberglass help extend the low end if you wanted to keep the pro driver in? Or is it already at or past optimal?

I love what you've done.

[demon]

hey your amps, are they alright?
i hope that just the fuse was blown!

your speakers really look nice, how they sound, i can only imagine.
(--good)
i think i will go D I Y too now.
:barf:

cheers,
mikey

[vernb]

thanks guys.
I think the idea perhaps is to sometime in the future, get a pair of matching 60 litre cabinets with the LE-1400h drivers in, an stack them....

That would give the extra LF extension, but take up the rest my breathing space in my already small living room.:barf:

At least they would look more of a K2 clone than they do now:D

[vernb]

Finally I decided to keep in the pro drivers. After hours of listening and adjusting, the conclusion is that the 1400ND PRO sound much better in the MF region where they are playing up to around 700hz. The very deep bass was deeper with the LE-1400H but the rest is better with the 1400ND PRO.

So my final setup is JBL 276ND drivers (on H3100 horns) and 1400ND PRO bass drivers. 3.5 cubic feet (100litre) cabinets, reflex loaded.

Thanks for all your comments and help. It's been fun
Vern

[demon]

well this looks all very good to me, particularly the pioneer specs --i always wanted such.
(i got the sa 95oo at least)

since im going DIY too in the near future i might have to come back to you with some questions. my project is somehow similar, wll, anway be prepared!

cheers,
mikey