HiVi D6.8 versus RS180

[TNRRClassic]

I have heard the RS 180, but have never heard the HiVi D6.8. I am probably going to do a pair of the RS52 three ways whenever they get figured out, and I don't know which woofer to use. Does the D6.8 have any real advantages over the RS180 that would make it worth the price difference? I have also thought that the D6.8 might require fewer crossover components than the RS180, which could minimise the cost difference. I look forward to some feedback, as the sale at PE goes out soon.

[joecarrow]

I don't know that you could say that the D6.8 is better than the RS180; I just spent a couple minutes at Zaph Audio looking at the comparison application, and it looks like below 1khz the RS180 consistently has lower distortion than the D6.8.

The RS180, like all woofers with deep cones, can cause some diffraction effects from having a cavity in the front face of the speaker. The D6.8's cone shape reduces that greatly. It's not a huge issue, but it's something to consider. Another thing to consider are the notably different T/S parameters between the two drivers. I think that the D6.8 could be happy with a smaller box than the RS180, especially sealed.

[WillyD]

I believe that Jon has said the D6.8 performs better (as far as bass is concerned) in a smaller box than the 180.

[cotdt]

the D6.8 has better bass and sounds more lively, but the RS180 sounds cleaner and more detailed. the RS180 has lower distortion.

[Jed]

Another one to consider is the SEAS CA18RNX. I'm pretty amazed by the bass coming from this 7"er. I'm using it up to about 400hz in a 3-way.
Jed

[TNRRClassic]

Well, one of the reasons I ask is that I like to use sealed enclosures, and I have run some box simulations that showed that the D6.8 would require a smaller box. I like the Modula MT, but it is not what I would call a very top of the line speaker, being a two way. They certainly sound great, but I think a three way might be a little better. A three way with a pair of D6.8's might be able to perform well in a much smaller enclosure than the RS180's.

[WillyD]

That is true...maybe you would like the three way that Jon is designing. He is developing one version of the xover with D6.8s.

[technimac]

Looks to me like the HiVi D6.8 is well suited to a smaller enclosure, so once Jon's WMTW design is posted, I'll be using a pair of them, along with the RS52 and the Vifa D26NC55 for a center. To me it's worth the price-premium to keep the center as small as possible. :T Because tomorrow's the last day of the PE sale on the D6.8's, I ordered a couple of those today for this project.

OTOH, because the RS180's like a larger enclosure, I'm thinking of using them in floor-standing towers with the RS52 and D26NC55 for mains. According to Jon Marsh, somewhere between 50 & 60 liters (vented) should provide maximum low end extension with two RS180's in these enclosures. So that's what I'm shooting for.

A question I do have is, would the crossover have to be radically different to make these towers a TMWW configuration instead of mirror-imaged WMTW's? And would performance suffer?

The reason I ask, is that with the tweeter on top, TMWW towers could be built much shorter with a correspondingly higher SAF. :W

[JonMarsh]

The problem with a TMWW configuration could be the overall CTC spacing- I think it would work, but the driver loading on baffle (midrange BSC) may be somewhat different, so some adjustment to the crossover would probably be needed. It might be close, but without running a test baffle, I'd be careful.

I'll see if I can put getting another test baffle and testing drivers in that configuration on my to-do list- but free time has evaporated this month, (day job you know), a new baffle evaluation will be a bit later- I should have the original baffle done this weekend if the router bits arrive as planned.

~jon

[technimac]

The problem with a TMWW configuration could be the overall CTC spacing- I think it would work, but the driver loading on baffle (midrange BSC) may be somewhat different, so some adjustment to the crossover would probably be needed. It might be close, but without running a test baffle, I'd be careful.

I'll see if I can put getting another test baffle and testing drivers in that configuration on my to-do list- but free time has evaporated this month, (day job you know), a new baffle evaluation will be a bit later- I should have the original baffle done this weekend if the router bits arrive as planned.
~jon

Jon, Thanks for the quick feedback. Your comments have given me some hope for the prospect of being able to do a TMWW configuration with these drivers. Your offer to try to put together a test baffle in that configuration on your to-do-list is very generous. TIA...
There may be others who might be interested in this configuration as well.

As it is, I don't know how you manage to fit everything you're doing into our Earthly 24 hr days. What I do know is that your advice and contributions are highly valued and appreciated.

Looking forward to seeing the results of your evalution of the WMTW baffle, once all the tools etc are available.

Cheers, Bruce

[TacoD]

Another one to consider is the SEAS CA18RNX. I'm pretty amazed by the bass coming from this 7"er. I'm using it up to about 400hz in a 3-way.
Jed

I second that.

I recently designed a 2.5 way with ca18rnx and also a 2.5way with RS180, both speakers are performing very well. The biggest difference is caused by the nature of the drivers and the xo-filter (the Seas has 3rd order bessel slopes ~ 2kHz, while the dayton had a CE-Jon filter around 1200 Hz). While the dayton has an edge in clarity and distortionfree presentation. The Seas combo did perform better in bass extension and reserve. But could not match the precision in presentation from the Dayton. IMHO The Seas combo performed better with mediocre electronics (run of the mill HT receiver, entry-level Denon stereo amp). The Dayton showed his merits on better electronics (performance scaled with quality electronics).

Unfortunate I never used the HiVi driver you mentioned.

[TNRRClassic]

Well, thanks so much for all of the helpful responses. i picked up a pair of D6.8's and a trio of RS52's. I am going to use the HiVi woofers for the centre channel of the WMTW in order to keep the enclosure reasonable. If there is a positive result for WWMT's with RS52's, I will make up a set using the RS180's in a larger enclosure. I think that should be a pretty good WWMT main, as the enclosure can be a bit larger than a centre and take advantage of all the clean bass the RS180 can put out. I can't wait to see what sort of crossover Jon and the others come up with . Thanks again.

[Jed]

I second that.

I recently designed a 2.5 way with ca18rnx and also a 2.5way with RS180, both speakers are performing very well. The biggest difference is caused by the nature of the drivers and the xo-filter (the Seas has 3rd order bessel slopes ~ 2kHz, while the dayton had a CE-Jon filter around 1200 Hz). While the dayton has an edge in clarity and distortionfree presentation. The Seas combo did perform better in bass extension and reserve. But could not match the precision in presentation from the Dayton. IMHO The Seas combo performed better with mediocre electronics (run of the mill HT receiver, entry-level Denon stereo amp). The Dayton showed his merits on better electronics (performance scaled with quality electronics).

Unfortunate I never used the HiVi driver you mentioned.

I'd be interested to know how the CA18 compares to RS180 with similar slope crossover- the additional clarity you experienced may be the result of crossing lower to a driver, in this case the tweeter at 1200 with RS180, more in its pistonic range- versus the CA18 with shallow slope @ 2K where beaming and increased midrange distortion occurs.

I don't notice much fuzzy warmth from CA18 up to 400hz, which is where I'm using them @ LR2. I like the CA18RNX so much for bass I might purchase another pair to do WWMT instead of the WMT I'm playing with right now, while I work on my much more complicated Usher, 12M, and HDS 3-way project.