ZAPH L18, BSC issues.

[peterpan]

I will like to build this design as a floor stand. I can only place my speakers near the wall with about 20-30cm to spare at the back of the speaker to wall. I understand the BSC is about 5dbs.Will this be too high for my application, if so ,what can Ido? peterpan

[LaMa]

It helps when you elaborate a bit more on your problem/question.
To start with the exact type of design you are referring to.

I assume you built this speaker?

To reduce the bsc (or lift the mid-high) I suggest to lower the series inductor (L1) to 1.2-1.5 mH and also tweak the lpad on the tweeter (reduce the series resistor and increase the shunt 3.3 in series and 10ohm shunt will do the trick).

You have to try yourself what sounds best, it's next to impossible to design from a distance without knowing the design

[Zaph]

LaMa's advice is excellent. In fact, I had previously made up a reduced BSC version of this crossover. This gives a couple dB of lift to help compensate for the closer location to the wall. Here it is, followed by a disclaimer:

[Zaph]

Ok, now the disclaimer. Most speakers sound better further away from the walls. They will have smoother response and better imaging. The closer the boundary, the higher up in frequency the related dip and peak in the response from the out of phase reflection. As these response issues move higher in frequency, they become more audible.

Of course if you have placement limitations, almost all speakers will have have the same issue and there's not much you can do about it. I'd just like you to be aware of the issues.

Regards,
John

[LaMa]

Originally posted by Zaph
LaMa's advice is excellent. In fact, I had previously made up a reduced BSC version of this crossover. This gives a couple dB of lift to help compensate for the closer location to the wall. Here it is, followed by a disclaimer:

Thanks, luckely for me you published the original cross-over otherwise my educated guess wasn't so educated

[peterpan]

Thank you for you advice. I"ll try both and see which one I like.

[takayama69]

Hi, I just built the original L18 in tall standmounts (H=20") tuned 40 hz in a box approx. 18.5 netto liters. So far they are placed 4' from backwall and sounds delightful.

But their future destiny is to be VAF-ed up and placed on a matching tv bench W 8' x H 20" ...maximum 20" deep. I do like a "darker" sound..but if its too dark..:

Seeing the alternative x-over just being changed in the major coil and the tweeters parallell resistor, I make the assumption that its ok to tweak in the whole range from 2.2 mH -> 1.5 mH and 3.9->5.0 ohms without wrecking et.c phase tracking, lobing up to much.. or is ??

// Anders , Sweden

[takayama69]

o.k, now my Zaph L18 are done. For now. The filter has two options, full BSC and the "close to wall option", easily selected by two switches.

Volume is 19 litres, tuned to 40 Hz.

Hammerite silver is a wee bit bright, so in the future i´ll sand em down again and will mix silver and black hammerite for a more graphite-ish look. And then i sure will use a roller... So no close up shots this time.

Thanks again for a clean sounding design. / A Hoegberg , Sweden

[Ling Gowa]

John, have you given any thought to revisiting this design? In your article, you mentioned trying to cross at 1.7 kHz. I understand that there were issues. Last year, I listened to a set which used the Peerless HDS & L18 crossed at 1.7 and it really sounded amazing. The guy wouldn't share the schematic with me. I built two sets of your design for my nieces’ graduation gifts, they like them allot. I just got one pair back because one niece is going out of province to take some courses and will return in May. So, I’ve had a chance to listen to them again downstairs in my ‘leave me alone’ room.