Have for some time been working on a set up new PC speakers.
I spend a lot of time in front of my PC screen, and I thought I deserved to have really good sound when listening to music.
I decided for a 2 way with waveguide to improve the directionality. I’m considering to further upgrade with either slots on the side a la the Dutch&Dutch 8c, or small extra mids to even further improve the Constant Directionality further down in frequency. But that will be for a later post. The drivers are crossed over by DSP, which is also used for smoothing out the frequency response.
For the woofer I chose the SB Acoustics 15NBAC30-8. The NBAC series have been shown to have very low distortion, and in general really high-end capabilities. I was also considering the SB Satori MW13P-4, but the price is double and it’s unsure how much better it is.
For the tweeter I wanted a driver which is capable of being crossed over really low using a waveguide.
Candidates where:
- ScanSpeak D2608/913000 ****
- ScanSpeak D2604/833000 ****
- SB26ADC-C000-4 ****
- Peerless DA25BG08-06 **
- Peerless DA25TX00-08 *****
All are priced reasonable, and all have very high performance. For analysis I used the HiFi Compass site which has great measurements of, the Italian DiBirama, and a lot of other sites and information you can find on the net.
To get low distortion at low frequencies you need a large diaphragm (Sd) and high excursion (Xmax).
The Peerless DA25TX00-08 excels in both areas. It is a newer driver with excellent specifications, the diaphragm is made of Corundum. Corundum is a crystalline form of aluminum oxide, a mineral which is super hard. Where Diamond is a 10 on the MOHS scale, Corundum is a 9 !!!
It’s hard to find much experience with the driver on the internet, so probably not a unit which is used a lot, which is a bit strange in my view as it on paper is an excellent and very cheep driver for the build quality. It even has a big heatsink which also doubles as a rear chamber, to allow for extra high power capability.
To make a long story short, I was very unlucky when trying the speaker for the first time, as my old Marantz amp messed up and vent into oscillation which resulted in an insane high sound through the tweeter and the dome had made such high excursion that it had hit the protective grill and had been bended! That it dd not burn and that it made such high excursion, is a tribute to the construction … don’t thing many tweeters would have survived.
As with much else in this world right now, new tweeters could not be had for a reasonable price as they are in back order! Therefore I had to chose a different tweeter, and the choice fell on the SB26ADC-C000-4. This tweeter is by the way used in Ravel Performa 3, which actually also goes for the SB15NBAC30-8.
Peerless DA25TX00-08 Sound
I have often concluded that the in room frequency response is the most important parameter for good sound.
On the Peerless DA25TX00-08 tweeter I was able to hear the sound change by only adjusting 0.5 to 1 db.
The sound is clear as a mountain lake, and you can play really loud without the character changing, and without getting to sound pressed or irritating to the ear.
The imaging and stage is very clear, but lacks some airiness or space.
I’m wondering on whether the fit with the waveguide was good enough. To use the Visaton WG 148 R waveguide I had to make a small adaptor of a plexigalss plade to act as spacer, and used medium hard foam between the tweeter faceplate and the waveguide throat. The throatdiameter is a bit larger then the dome itself, so if you had a better matching throat, maybe you would get better results. Even though the raw driver without waveguide has an almost flat frequency response, some adjustments was needed by the DSP. In both cases I have been using a Xover frequency of 1800 Hz.
I would think the Peerless tweeter would be perfect for hometheather use, in the front and center, with the very high db capability and the laser sharp sound.
It should of coure be noted that as the one tweeter did get a bump, which was measurable, it will for sure have had an influence on the overall stereo result. So who knows how it would have sounden that it not been damaged?
Another thought is to add a small phase plug to the Peerless tweeter, like the one used on the SB tweeter. This helps avoiding a dip in the freqency response at high frequencies. This could simply be done by placing a small round piece of plastic on top of the tweeter grill.
SB Acoustics SB26ADC-C000-4
The SB Acoustics SB26ADC-C000-4, has a clear and more relaxed sound, maybe you could say not as detailed. On the other hand the room is broader and more spacious.
The sound is really easy to live with, and gives a lot of pleasure.
The waveguide did not fit much better than for the Peerless tweeter, but no DSP frequency response ajustment was needed … it’s just flat.
So if you are not using DSP, then the SB tweeter will be so much easier to work with.
In both cases the overall I setled for a lightly sloping frequency response (house curve) towards the high end by ca -5 db from ca 1 to 20 kHz.
How to choose? I think both tweeters are super drivers, selling for a very resonably price. Whne I can again get the Peerless tweeter for a resonal price I’ll pick up a new set and experiment again.
