New 4 way project comments/suggestions?

[FullThrottleRic]

Hi everyone.

I'm looking for a new challenge, so I've decided to have a go at a 4-way system based around the ATC 3" domes.

They will be used for the fronts in my HT setup, so the design criteria are low distortion, reasonable bass extension and DYNAMICS!

I'm pretty much decided on the tweeter (SS 9500's) as I use them in my current speakers. There are probably better tweeters about but I want to keep the cost of this somewhat reasonable and anything that's significantly better I assume will be expensive. I'm planning to passively cross these to the ATC's at 3.5kHz or so.

The upper mid will be the ATC SM75.150, no point in going for the 'S' version as I'll only end up padding the extra 3db back down and from what I've read on the net they don't sound any different to the 'cheap' ( ) ones anyway.
Again I'm planning on passively crossing these over to the lower mid driver at 500Hz or so, I know ATC use them down to 380Hz but if I'm using a 6.5" lower mid (see below) the baffle step will be centered somewhere around 500Hz given a 22cm wide baffle. Which should make it easy to compensate for with the lower mid level. A higher crossover should also reduce excursion and hopefully distortion.
Does anyone have experience with the ATC's and passive crossovers, and will there be an issue with them being 16ohms impedance? I'm guessing the best way of padding them down to match the other drivers will be a resistor in parallel at the driver end of the crossover? This should both match the levels and go some way to bringing the impedance back into line with the rest of the drivers?

The lower mid and bass is where I'm still a bit unsure what to do. I'd like to use the Peerless XLS 10's for the bottom end, either a single driver or 2 in and M&K push-pull style enclosure with a driver on the bottom. Now the XLS's look like great bass drivers but the frequency response gets a bit wonky above 500Hz, so it looks like it wouldn't be ideal to expect them to go all the way up to the ATC by themself. To get around this I'm planning on using a 6.5" driver to cover the 100Hz - 500Hz gap, actively crossed over to the XLS's.
After reading Zaph's midwoofer roundup it looks like the Seas W18NX-001 fits the bill perfectly, the only issue is the low 87db/w sensitivity. Without using two what would everyone else do as padding the ATC and SS down 5 or 6db's seems like a waste to me.
I's a bit hessitant to use an active crossover on the ATC as I don't want an amp problem blowing a £280 drive unit

Would there be any issue using an active lowpass on the Seas, combined with a passive highpass on the ATC? That way I should be able to run the tweeter and ATC pretty much without attenuation, and set the levels using the gain on the amps.

Sorry for the long post, any comments/suggestions welcomed

btw, I'd like to be able to buy the components in the UK, which pretty much limits me to ScanSpeak, Seas, Peerless and Vifa. No Dayton/HiVi ect suggestions please

[tinitus]

Well, you are in for some serious trouble

Using two 3" you need a powerfull lowend...one 6.5" and one 10" dont cut it....in that case I think one 3" would do

If I were to do it with 2 x 3"....I would do it 3-way, and I think it would need something like 4 x 10"

[FullThrottleRic]

Sorry if I wasn't too clear, for each speaker I'm looking at...

1x SS D2905-9500 (Passive highpass ~ 3.5Khz)
1x ATC SM75.150 (Passive bandpass ~ 3.5Khz and 500Hz)
1x Seas W18NX-001 (Active bandpass ~ 500Hz and 100Hz)
1 or 2 Peerless XLS 10"s (Active lowpass ~ 100Hz)

The top three drivers will go in their own enclosure (something like a teardrop shaped translam if I'm feeling brave ) and the XLS's in their own stereo subwoofers under each main speaker.

[tinitus]

I am not sure one 6.5" is enough for the ATC 3"

Maybe you could use an 8" AudioNote or similar

You might want to read this(all of it)

http://www.troelsgravesen.dk/HES_II.htm

[ShinOBIWAN]

Originally posted by tinitus
I am not sure one 6.5" is enough for the ATC 3"

Maybe you could use an 8" AudioNote or similar

You might want to read this(all of it)

http://www.troelsgravesen.dk/HES_II.htm

The ATC standard dome quotes a sensitivity of 91dB which is optimistic. I use the super version now but when I worked with the standard you'll need to EQ the response to flatten the response in the end I had about 88dB after this, obviously the driver is working less where you've lowered the gain to flatten the response but overall sensitivity and ATC's peak value of 91dB are different. Just for comparison the super is around 91dB eff. after EQ.

So that means you'll need 2 XLS's and a lower mid with an eff. of ~90dB so as to compensate for baffle step and also avoid sucking the life out the speaker by using way too much padding.

If it were me I'd go with:

Seas T25C003
ATC SM75-150
Supravox GMF215
2x XLS10's

With the crossover points at 3.1Khz, 600hz and 100hz.

I'd also go active for the whole lot or at the very least the 100hz cross to the XLS10's because passive networks crossed is expensive and not ideal.

I'd also strongly recommend not using the XLS10's above 150hz, they're just don't sound very good up high and probably due to the high inductance.

For passive a more ideal solution would be to go 3-way and use

Seas T25C003
ATC SM75-150
1 or 2 x Supravox GMF285 (aperiodic loading)

With XO's at 3.1Khz and ~600hz.

And then use a sub to augment the lowest regions. If you don't fancy a sub then you'll have a hard time crossing to the ATC standard as it doesn't work very well below 400hz, the super version will work down to around 300hz. Finding a driver that will reach to 20hz and be able to cross at 300hz/400hz *and* still match the quality of the ATC dome will be a tough call. If you insist on the ATC then the best results will come from a 3way+sub or a 4-way active.

Best thing to remember is there's many ways to skin a cat.

[tinitus]

20hz to 600hz.....maybe multiple Adire Exstremis would

[FullThrottleRic]

Thanks for the replies guys.

So I was right in thinking the little Seas would be working too hard to keep up with the rest of the system.

If I can simplify the system I'm all for it, I would like to use the ATC though as it's something different and obviously very good if properly implemented.

I would like to stick to the Scan tweeter, although the Seas you suggested Shin is reasonably priced so thats not out of the question. Is that the model ATC themselves use in a lot of their speakers, it does look similar? The Supravox's are out of my league though, I just looked at their website and they had $1200 next to them

I'm not 100% set on using the XLS woofers, if there is a decent quality woofer that can reach up the the domes that would be better. I know you had trouble finding a woofer for your Percieve's, do you mind me asking where you got the ATC woofer from and how much it was? Wilmslow don't sell any of ATC's drivers other than the domes, I imagine they would be able to get hold of the whole range but being Wilmslow they will be a lot more expensive than they should be
I already have a subwoofer that reaches <20Hz so low end extension to 40Hz or so would be fine.

For the moment I'm going to have to go for passive crossovers on the tweeter and mid. I really dont have the money/space for 6-8 channels of amplification just for the front pair, I also don't have much experience with active filters/equalisation. Bi-amping the woofer section isn't a problem as I have a couple of channels free and the filter should be reasonably simple.

[Jonasz]

3,5k- SS9500
500-3,5k ATC SM75-150
20-500 one or two Dayton RSS10"

Would make an awesome system!

[tinitus]

9" ATC .....I have been listening to ProAc response(4?).....listening close to the 9" cone....a lot of strange noice.....dont like that

I liked 12" ATC much better

[pinkmouse]

I'd be looking at the Volt B250.8 or the B2500.