TNT Nues mkII DIY Loudspeakers

TNT Nues mkII

New tweeter and cross-over for our Nues

Product: TNT Nues - 2-way floorstanding loudspakers
Producer: not for sale, TNT-Audio DIY design
Adopted drivers: Coral EL 61 (2 woofers), Ciare HT259 (1 tweeter)
Approx. price: 200 € (basic stuff); 50 € (only upgrade)
Author: Fulvio Marcolin
Publishing dates - original project: July, 2001; MKII: April, 2007

Why an upgrade?

[Nues mkII]

The TNT Nues design was originally published on july, 2001, and I don't know exactly how many of our readers actually built this DIY loudspeaker. Anyway, I can say that the feedback received by those people who built it has been positive. The first strong point of these loudspeakers is the q/p ratio: entry-level drivers are used, yet they sport good performances, if properly used. Their easy assemblage allowed - also to the newcomer diyer - to be able to build the Nues.

Anyway, some diyers highlighted certain weak points of this loudspeaker, which should be fixed with this upgrade:

- Coral's tweeter power handling is limited, 10 watts, and someone managed to burn it. So we looked for a substitute tweeter for the EL10, and we found Ciare's HT259: its declared nominal power is 60W, with electric parameters similar to the EL61's; besides, its size allows for tweeter substitution with no need to change the cabinet: you just need to drill different mounting holes.

- Mid-high region response was not as good as the low section's one: the old tweeter would sport some of cheap drivers typical faults, so it sometimes sounded harsh and opaque. The HT259 tweeter, during listening sessions, showed to be of bigger value than its price would suggest, being able to render a bigger depth and a sharper instrument position.

Cross-over has been modified to limit the tweeter's output and to improve the loudspeaker's response in the frequency range around the crossing point between woofers and tweeter.

The drivers' crossing frequency has been raised to about 2,100 Hz, to limit physical stress of the tweeter, plus a woofer compensation cell has been added. The network, anyway, remained structurally simple, so it should be also easy to build. The loudspeaker's average impedance is about 4 ohms, so, if you happen to own a good (speaking in ampere terms) amplifier, you will not have problems. Any amplifier (even a 20 watter) of decent quality will be able to drive the Nues. Obviusly, the bigger your room, the more powerful the amplifier. The Nues' average senitivity is fair (88,5 dB/m/2.83V).

Tweeter substitution

Coral and Ciare tweeters sport similar size, so the housing hole will not change. But you need to drill new mounting holes, since their interax is slightly narrower. Remember to put back the gasket between the cabinet and the tweeter's face plate.

Building the crossover

It is possible to recycle some of the old crossover's components. For the assembly (see picture), I preferred to work on the Ciare printed board whose code is YCS001, an universal DIY module for 2-way crossovers that allows even the less expert to achieve the best results. Capacitors: 100V, non-polarized, with polypropilene dielectric.
Coils:
* 0.64mH - 1mm wire gauge - 0,4 ohm - air wounded
* 0.4mH - 1mm wire gauge - 0.3 ohm - air wounded

[Nues mkII Cross-over]

Materials availability

The tweeter needed for this upgrade was choosen also because of its easy availability both in Italy and abroad. For informations about the nearest dealer, I suggest you to browse the Ciare website. Among the shops that carry this driver and that sell also online, I'd suggest the following: Audiokit and Digitex. Passive components (capacitors and coils) can be found at any electronic material supplier.
Clio-based measurements. Thanks to the cooperation of Florence's Audiomatica, I was able to perform the TNT-Nues loudspeaker's third-octave in-room response measurement. I am talking about real measurements, not project simulations, here.

Conclusions

I must express my most sincere thanks to Ciare, expecially to Lino Esposto, for their drivers' availability, and to Florence's Audiomatica for allowing me to utilize the famous Clio PC board. A thank-you also goes to those who allowed for the listening session: Giorgio Pozzoli and Matteo Bresciani.

[Nues mkII - Clio]

Good work and enjoy. We wait for your comments and opinions.