My new-to-me 820s

**wws944** · December 9th, 2012, 04:21 PM

Was talking with the owner of a local high end audio shop yesterday and got into a discussion of crossovers for the 820s. Besides the capacitors, the topic of the coils came up. According to the N800D schematic, the stock crossovers use iron core inductors. I was musing over whether air core would be better and he was fairly adamant that air cores are the way to go. OTOH, considering how efficient these horns are, would the stock inductors get to the point where they start to saturate?

If I bought some air core inductors along with the new caps, I may as well just build my own crossovers - rather than retrofitting the new parts into the N800Ds. I would simply follow the N800D schematic - unless someone knows a good reason not to.

**cradeldorf** · December 9th, 2012, 09:19 PM

I'm gonna do Iron cores on the LF side and Air core on the HF side. I didn't like how the air cores sounded on the LF side. And not real happy with how Iron cores sound on my HF side. I have iron core on both now but the air cores for the HF side will be here Tuesday.

**wws944** · December 10th, 2012, 10:23 AM

Originally Posted by cradeldorf

I'm gonna do Iron cores on the LF side and Air core on the HF side. I didn't like how the air cores sounded on the LF side. And not real happy with how Iron cores sound on my HF side. I have iron core on both now but the air cores for the HF side will be here Tuesday.

That is a useful observation. I guess I would have expected the opposite - since the high power, where saturation might be an issue, would be on the bass side.

Which air cores did you go with?

**cradeldorf** · December 11th, 2012, 03:41 AM

Ummm I don't remember, The 16 gauge 1.5 Mh from parts express. which is actually up from the 1.1 Iron core Erse I was running. It seems like most crossovers I've seen have the same Mh coils on both sides where I was running a 1.5 Iron Core 0n my LF and a 1.1 on my HF.

**johnny_fever** · January 2nd, 2013, 12:09 PM

Whats the time frame on the Cabinet work? Cant wait to see the pics. Thanks for all your help. Rick

**wws944** · January 3rd, 2013, 03:56 PM

Originally Posted by johnny_fever

Whats the time frame on the Cabinet work? Cant wait to see the pics. Thanks for all your help. Rick

Soon, I hope. We were thinking they would be done by the end of December, but Life got in his way.

**wws944** · January 8th, 2013, 11:16 PM

Update: We spent a fair amount of time this evening marveling over the numerous differences in construction between the two cabinets. Some of which are very visible back in post #1 of this thread.

Measurements of the DC resistance on the woofers are:

Gray (1955 - 12 ohm rated) set: 8.6 ohms + 8.6 ohms measured
Green (1957 - 16 ohm rated) set: 8.3 ohms + 8.3 ohms measured

Compression drivers are:

Gray (15 ohm rated): 8.8 ohms measured
Green (16 ohm rated): 8.3 ohms measured

Do these DCR values seem low? At least they are pretty consistent with each other.

Still under discussion is if we should replace the crossover caps in the N800Ds or not. Both N800Ds have 10.5 mfd caps in them, but he has not had a chance to measure them and see if they are still in spec yet. (As a friend of mine likes to say - "To measure is to know".) If the caps are out of spec, it may just as easy to leave them as they are and build new crossovers. Or maybe bi-amp them? (I could buy a cheap Behrenger active crossover for what new crossovers would cost. I already have the amps.)