N800F Question.

**timp** · January 4th, 2008, 09:45 PM

I am making a full circle here. For my 414-16b I decided to clone the N800F after all. I should have listened! forums

But what I did not understand was that the N800f parts values which were 3mh and 10.5uf. Were these intend for 8ohm drivers or two 414-16bs in parallel? Then I just need to double the inductor value and half the cap value. Right? I hope I am getting this one right.

Thank you.

Tim

**bfish** · January 4th, 2008, 10:12 PM

Hi Tim,

That's somewhat of an enigma. The N800F that was the source for the schematic and values was from an 846A Valencia with a 16 ohm 416 and a 16 ohm 806A. Several other Val owners report the same configuration, and that's the way it's listed in the parts reference. However...

N800Fs also came in several cabinet versions that had TWO 16 ohm 414s and an 806A...and what's more...

The decal for them says they can be driven from either 8 or 16 ohms...

Several heads have been scratched over the matter, and only one conclusion was really reached...they work anyway, so who cares...

**timp** · January 5th, 2008, 01:05 AM

Hi Bfish

That's beyond my understanding. I've tried various second order butterworth combos, using online Xover calculator of course, and finally 6mh+5uf combo. And the last one sounded the cleanest to me. I know this purely is a subjective experience in my behalf. So I thought the 6mh+5uf was the 16ohm equivalence of n800f. I thought I was getting smarter

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Thanks very much.

Tim

**bfish** · January 5th, 2008, 05:40 AM

Given the odds that the N800F designer is no longer with us, we'll likely never know "why"...

Altec only made one model I know of with your components, and it used an N800F. That's why I suggested it. Since it was used in such a broad range of applications (and apparently worked well in them given the number produced), it stands to reason that optimization for a particular app (yours) is likely possible.

There is more to consider though than just shotgunning XO values (though there's nothing wrong with that within a reasonable range). Did you notice the specific instructions for wiring polarity based on the horn mounting location in the old enclosure guides? How/where is the horn located? How are your boxes tuned?

All I'm getting at is to suggest you might be working on the carb when the fuel pump is the problem... forums

**timp** · January 5th, 2008, 02:04 PM

Hi Bfish

You got me cold. I've been using a grenade method. Using the nominal impedance and online calculator and using n800f as a guideline.

I followed 614 instruction. Altec indicated that the optimum volume for the 414s would be 3.5Cft with 2"X7 duct. Mine are 3.75 (internal volume).

The horns are sitting on top of the cabs with L-pads as you suggested. Would you please tell me about the polarity? I did not even know that there was specific instructions.

Finally. I opened up the rear cab of the compression driver which to my ears gave more open sound.

Thanks Bfish.

Tim

**bfish** · January 5th, 2008, 03:10 PM

You'll find some polarity hints here on pages 7, 10, and 13;

http://www.lansingheritage.org/html/...960s-plans.htm

It boils down to getting both the horn and woofer in phase at the crossover point, and the relative mounting locations of the two plays a part in that. If the reference makes little sense, don't be afraid to try things with the horn polarity both ways. Once you find the best polarity, you can "fine tune" things a bit by lttle forward/rearward adjustments of the horn. If you change the basic topology of the XO, you'll have to start all over too.

As you've discovered, trying to set things up from scratch is pretty tricky without any way to measure the results of what you do. It's even harder to help from this end. forums

Not to worry, we won't give up on ya.

It might help for setup and experimenting to use a mono source if you have that option.

Hang in there! forums

**bfish** · January 6th, 2008, 01:51 AM

Originally posted by timp:
...Is this acceptable for bass reflex models?...

<font size="2" face="Verdana, Helvetica, sans-serif">I'd call it overkill. Since you're not trying to add virtual volume, all you want is enough to stop standing waves, usually just 3 sides, one in each axis. With your components, the 414 is already "running behind" the 806 (which is why you have to pad the 806), so you don't want to waste any of its' energy in excess absorbtion internally.

If you can tolerate fiberglass, use ~2", or a little more for polyfill ("honey, have you seen our couch pillows today?"). forums

Save the PE foam to put on the nearest hard surface to your speakers.

If you need to, raise them till the horn is at ear height where you listen.

If they're a little bass poor (which they are) get 'em in the corners if you can...mo' bass.
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**timp** · January 6th, 2008, 04:15 AM

Hey Bfish thanks for the reply.

Thanks for the reference. It was a real good reading for me. I will play around with my speakers in mono setting.

I do have a question though. For cab damping I used this: http://www.partsexpress.com/pe/showd...number=300-900

Is this acceptable for bass reflex models? I used them thinking they were the best. But what do I know? I think this more than I can chew for now. So I shall return.

Thanks. Tim

**timp** · January 6th, 2008, 04:15 PM

hey big fish I got you. I will indeed change the damping. what can i say? I want my speaker to sound good. So, the change is coming. I am just excited that I am making one more improvement to mh speak.

Thanks Bfish.

Tim