my A7s are up and running- and 416a magnet questions

[bowtie427ss]

This might partially explain why my findings differ so much with the consensus that 90 sq in is the best set up. As time passes, and things stabilize, naturally, I will try the smaller ports again- and other sizes.

Don't overlook experimenting with adding a bit of series resistance to the circuit to help smooth your bottom end response.

[SD-50]

Been experimenting with various XOs for my A7s, completed and installed a new one yesterday evening. It`s a 2nd order Linkwitz-Riley, X point at 600hz, it replaces a 1st order XO that had troublesome peaks. Have a few other XOs to test before settling on a final choice.
The cab is an 828 with 511 horn, 808 diaphragm, 416c woof, 802 replacement soon.
Anyway, the system subjectively sounds better, music is layered and spacious and those annoying peaks are less noticeable. Not owning any test gear have to rely on my ears and the bedroom 604 system for evaluation and comparison.
Sorry no pic, royal PIA uploading pic here, Photobucket just as bad.

[SD-50]

Created a Photobucket account, major PIA, if all worked out you can view the XO pics here.
http://s1380.photobucket.com/user/CX...?sort=3&page=1

[horndawg]

Created a Photobucket account, major PIA, if all worked out you can view the XO pics here.
CXryder's Library | Photobucket

After the recent fiasco with photobucket and the broken image links on just about every forum on the net, it's beyond me why anyone would still use them as a hosting site.

On a more pleasant note, that's a nice crossover layout. What oil caps are you using?

[kipduff]

Don't overlook experimenting with adding a bit of series resistance to the circuit to help smooth your bottom end response.

Could you be more specific? In series with LF and/or HF? Ohm value?

I'm trying to troubleshoot some pretty aggressive mid/highs from the horns that don't show up on the frequency response curves. Right now using old 1987 Audio Reasearch SP-9 preamp- or no preamp (streaming direct to amps from DAC) . Could be synergy issue- will have a better idea when I complete my Bottlehead BeePre preamp and Bottlehead Eros phono stage- should be good match with the Bottlehead Paramount 1.1/300B amps.

[SD-50]

After the recent fiasco with photobucket and the broken image links on just about every forum on the net, it's beyond me why anyone would still use them as a hosting site.

On a more pleasant note, that's a nice crossover layout. What oil caps are you using?

These are Aerovox, have various brands of PIO and bunch of Soviet Teflon caps plus some massive caps recommended by Lowohms, no longer on the board.
Only used PB to post the pics as I was having problems posting here. PB was a nightmare creating an account, then non-stop pop-ups, site is done!
Cheers

[Earl K]

Could you be more specific? In series with LF and/or HF? Ohm value?

I'm trying to troubleshoot some pretty aggressive mid/highs from the horns that don't show up on the frequency response curves. Right now using old 1987 Audio Reasearch SP-9 preamp- or no preamp (streaming direct to amps from DAC) . Could be synergy issue- will have a better idea when I complete my Bottlehead BeePre preamp and Bottlehead Eros phono stage- should be good match with the Bottlehead Paramount 1.1/300B amps.

I'll suggest that to find ( & then adequately address ) the "aggressive mid/highs" from your horn/driver combos, you are going to need to start looking at CSD & Sonogram traces of your files.

Here's a normalized CSD (EQed to being "flat" by the program ) of a 902-8B on an non-terminated 511a ( done by Zilch ).



And then the sonogram version :



To offer you some perspective ( 25-cent analysis ); between 1K-3K there are some very strong sustained resonances that are just 10db down from the frequencies fundamental .

Minus 10db represents @ 50% ones listening experience ( from the physco-acoustic perspective ) .

Meaning 1/2 of what you are perceiving ( with an unterminated/ under-damped 511 ) is actually horn ringing .

As a comparison, here's an ARTA Sonogram of a 802d ( fitted with 35480 diaphragm > the same as above ) on a cheap plastic horn called the PH-230 ( made by P-Audio & a couple of other makers ).

I EQed this combo to be flat using passive components . This horn/driver combo was also free-standing .



These horn/driver resonances ( at minus 20db ) are about 1/2 as much again or 1/4 as much ( when compared to the 511/902 combo ).

I'll suggest that limiting horn/driver resonances to minus 30db is a reasonable goal to shoot for ( while doubting that few actually achieve even that ) .

The forums are littered with lots of good suggestions ( for resonance control ) by using mass-loading of the horn body, bell-terminations into a typical Altec horn-sled, etc. etc. .

( IMHO ), it's time for you to try them all to increase the quality of your auditory experience /// plus now you know how to log progress ( from a measurement perspective ).

[Audio_by_Goodwill]

After the recent fiasco with photobucket and the broken image links on just about every forum on the net, it's beyond me why anyone would still use them as a hosting site.

The links are broken because Photobucket is charging for 3rd party hosting now..... the pictures are still there, but you have to visit Photobucket to see them unless the account holder pays the rather enormous yearly fee. It's not a technical glitch, it's a change in their business model.

[horndawg]

The links are broken because Photobucket is charging for 3rd party hosting now..... the pictures are still there, but you have to visit Photobucket to see them unless the account holder pays the rather enormous yearly fee. It's not a technical glitch, it's a change in their business model.

Yes, it was a change in their business model but the way they did it - overnight and then charging to what amounts to a ransom for regular folks, was IMO a scumbag thing to do. I don't like rewarding greed by sending them potential business.