Still thinking about my 4-ways project with High-Midrange dome speaker, I was looking to the frequency response of the nice 3" ScanSpeak D7608-920010 dome midrange :
I thought that it would have been much more linear in axis incidence (above) in the 1000Hz - 7000Hz region, I mean : without that -5dB drop, compared to the Beyma 8M60N (below) that I use in my current setup :
In fact, I wonder if its output of barely 92 dB/w/m will be sufficient to complement the 95dB of the Low-Midrange Beyma... 🤔
T
I thought that it would have been much more linear in axis incidence (above) in the 1000Hz - 7000Hz region, I mean : without that -5dB drop, compared to the Beyma 8M60N (below) that I use in my current setup :
In fact, I wonder if its output of barely 92 dB/w/m will be sufficient to complement the 95dB of the Low-Midrange Beyma... 🤔
T
There are two types of Scanspeak D7608 dome mids, one without flange (920000) and one with flange (920010).
When comparing the two datasheet frequency curves, it turns out that there is no difference between these curves....they are exactly the same.
IMO there should be differences between two of the same domes, one without, the other with flange.
My conclusion is that the data are suspect and must be taken with a grain of salt.
When comparing the two datasheet frequency curves, it turns out that there is no difference between these curves....they are exactly the same.
IMO there should be differences between two of the same domes, one without, the other with flange.
My conclusion is that the data are suspect and must be taken with a grain of salt.
@tubelectron The lower mid performance of the D7608 will be greatly improved when a chamber is added. The factory FR data is measured without the chamber, so what looks like there's just a peak at 1k will be smoothed out down to at least 600hz at 90dB+. If SS would revise their data and add measurements with a chamber, it would help them sell more of these mids. The way it looks now, it doesn't perform that well thanks to that peaking and nothing down low.
I've been put off the SS dome since PMC used it in the IB1S and everyone was disappointed compared to the Volt in MB2 and BB5 then they used the Volt in the IB2S.
For sure the prices are high but the Bliesma drivers offer some interesting material choices.
I decided on the paper version of the M74 as an inbetween silk and metal.
Unfortunately I still only have pictures and no real data
This may help.
I found my old plots (2016) of the SS D7608.
The Blue trace is without crossover.
Red is 800Hz HP and 4kHz LP with electronic crossover.
Internal sub-chamber is 2L.
Regards
Mike
AmpsLab-Spk
I found my old plots (2016) of the SS D7608.
The Blue trace is without crossover.
Red is 800Hz HP and 4kHz LP with electronic crossover.
Internal sub-chamber is 2L.
Regards
Mike
AmpsLab-Spk
That's interesting. I used to own IB1s and loved them. I also used ATC SCM30s, which didn't sound as good in the mids, rather edgy and too forward. The reason I fell for the SS D7608s was due to the IB1 sound. My pair had revised xovers with upgraded parts. They were updated by the same guy who did work for Bernie Grundman and Doug Sax among other similar clientele.
The Volt VM752 has some phase and stored energy issues around 4.5k with a deep notch caused by a resonance. You need to LP this dome rather low and steep to avoid hearing this. There is a dampening mod you can do to reduce this by applying a bead of PVA around the dome to surround junction area. I haven't done this myself, but I've seen it on a few VM752/753.
What are people's thoughts on the D3806 going the way of the dodo? Seems an odd duck nowadays, but maybe still has value for 4-way + supertweeter fans?
The D3806 is a great sounding mid-tweeter. I've heard it used in 2 ways and together with a 19mm dome. Its a very clean but relaxed sound as a standalone tweeter but obviously doesn't have that much upper register extension. What is there is likely the best treble I've heard from a soft dome, close to the Seas T35C002.
The only main drawback of the D3806 is the cost. Its not as competitive of a driver when compared to many other larger diameter soft domes which can be run down lower than most typical 25mm domes. If you're someone who can't hear past 10k, its a suitable HF driver in a larger 2 way. Even the cheaper Audax TW034 has more top end air than the D3806. Its also more sensitive, but not nearly as refined sounding.
The only main drawback of the D3806 is the cost. Its not as competitive of a driver when compared to many other larger diameter soft domes which can be run down lower than most typical 25mm domes. If you're someone who can't hear past 10k, its a suitable HF driver in a larger 2 way. Even the cheaper Audax TW034 has more top end air than the D3806. Its also more sensitive, but not nearly as refined sounding.
there's another scanspeak 1.5inch tweeter I would have liked to try buy I think they've stopped making them now Scanspeak Classic D3806/8200-00, 1.5" Tweeter
This sounds similar to what we can see in ATC middome measurement in #159 and also in Troels measurements of ATC:
http://www.troelsgravesen.dk/ATC-SM75-150.htm
Thanks @Michael Chua !
This is a little more reassuring about the possibilities of this D7608 3" midrange.
I would use it in a 4-ways sealed enclosure, as follows :
BASS = Beyma 12BR70 (12" / 93dB/w/m)
FC1 = 300-400Hz
LOW-MIDRANGE = Beyma 8M60N (8" / 95dB/w/m)
FC2 = 2000-3000Hz
HIGH-MIDRANGE = ScanSpeak D7608-920010 (3" / 92dB/w/m)
FC3 = 6000-7000Hz
TWEETER = Beyma T2030 (1.25" / 95dB/w/m)
The "horizontality" of the frequency response showed by your graph would match quite fine - if the center line represents 92dB/w/m :
---1kHz------------------------2kHz-----------------------------------------------7kHz---------10kHz
And as @profiguy stated :
I think I'll invest and buy one to build a prototype, since I have all the other speakers in stock.
Or do you think that there would be an even better option in my case ?
T
This is a little more reassuring about the possibilities of this D7608 3" midrange.
I would use it in a 4-ways sealed enclosure, as follows :
BASS = Beyma 12BR70 (12" / 93dB/w/m)
FC1 = 300-400Hz
LOW-MIDRANGE = Beyma 8M60N (8" / 95dB/w/m)
FC2 = 2000-3000Hz
HIGH-MIDRANGE = ScanSpeak D7608-920010 (3" / 92dB/w/m)
FC3 = 6000-7000Hz
TWEETER = Beyma T2030 (1.25" / 95dB/w/m)
The "horizontality" of the frequency response showed by your graph would match quite fine - if the center line represents 92dB/w/m :
---1kHz------------------------2kHz-----------------------------------------------7kHz---------10kHz
And as @profiguy stated :
I think I'll invest and buy one to build a prototype, since I have all the other speakers in stock.
Or do you think that there would be an even better option in my case ?
T
Yes and same in Javad Shadzi measurement of the ATC in its beautiful project called omega (detail on its FB page)
