Nova 6 tweeter options (revisited, again)

[CarlQB]

Ok just a quick follow up after a couple months listening to the Nova 6 with the GT-25 replacement tweeters.
I previously wrote that I felt the GT-25 sounded a bit "sharper" than the originals, probably due to their higher sensitivity, but overall they did not sounded "shouty" of fatiguing.
I'm going to revise that a bit.
IMO the tweeters did sound a bit too present. Just a bit too much "in your face". Even with the tweeter level switch to the "low" setting.
So I felt maybe I could do something to tame them down, just a little bit.
I don't know much about crossovers. So I asked my good friend ChatGPT... haha!
I don't know how good or bad ChatGPT's advise is. But in the end, I think it turned out pretty good.
After a lenghty chat on crossover frequencies, the original design of the Nova 6 crossover, and the frequency response, impedance and sensitivity of the OEM drivers vs the new GT-25 tweeters, and what I wanted to achieve, GPT suggested I added a L-pad to the tweeter network. But I wanted to keep it more simple, like just adding resistors, as there already are resistors in the crossover level control switch.
Again I went into a lenghty discussion with ChatGPT on parallel vs series resistors of various values and the effect on sound and crossover frequency.
In the end, the recommendation was to replace the 1 ohm resistor in the crossover with a 4.7 ohms resistor. I didn't have a 4.7 ohms resistor with sufficient power rating around, so I used what I had, three 15 ohms 3W resistors in parallel, wich gave me 5 ohms with 9W capacity (way more that I needed).
I did not replaced the 1 ohm resistor of the crossover, I just added my 5 ohms resistor to it, and gave the speakers a listen. Honestly, I think they now sound very good. The brightness that bothered me is gone, they sound much more balanced, at the Normal setting.
According to ChatGPT, the added resistor decreased the tweeter level by 3 to 4 dB in the Normal setting, but preserved the tonal balance of the speaker.
I have not listened to a ton of speakers in my life, and I would not trade the Nova 6s with my current A25s, but for Radio Shack speakers that I got for basically nothing and fixed for little money, I'm impressed, they are smooth and very enjoyable, I'm very happy about them.
So my final recommendation if you replace the Nova 6 tweeters with the Goldwood GT-25s is to add a 5 ohms (or so) 5W+ resistor in series with the tweeters to tame them down a little bit, and listen to result.

 

[Lavane]

Ok just a quick follow up after a couple months listening to the Nova 6 with the GT-25 replacement tweeters.
I previously wrote that I felt the GT-25 sounded a bit "sharper" than the originals, probably due to their higher sensitivity, but overall they did not sounded "shouty" of fatiguing.
I'm going to revise that a bit.
IMO the tweeters did sound a bit too present. Just a bit too much "in your face". Even with the tweeter level switch to the "low" setting.
So I felt maybe I could do something to tame them down, just a little bit.
I don't know much about crossovers. So I asked my good friend ChatGPT... haha!
I don't know how good or bad ChatGPT's advise is. But in the end, I think it turned out pretty good.
After a lenghty chat on crossover frequencies, the original design of the Nova 6 crossover, and the frequency response, impedance and sensitivity of the OEM drivers vs the new GT-25 tweeters, and what I wanted to achieve, GPT suggested I added a L-pad to the tweeter network. But I wanted to keep it more simple, like just adding resistors, as there already are resistors in the crossover level control switch.
Again I went into a lenghty discussion with ChatGPT on parallel vs series resistors of various values and the effect on sound and crossover frequency.
In the end, the recommendation was to replace the 1 ohm resistor in the crossover with a 4.7 ohms resistor. I didn't have a 4.7 ohms resistor with sufficient power rating around, so I used what I had, three 15 ohms 3W resistors in parallel, wich gave me 5 ohms with 9W capacity (way more that I needed).
I did not replaced the 1 ohm resistor of the crossover, I just added my 5 ohms resistor to it, and gave the speakers a listen. Honestly, I think they now sound very good. The brightness that bothered me is gone, they sound much more balanced, at the Normal setting.
According to ChatGPT, the added resistor decreased the tweeter level by 3 to 4 dB in the Normal setting, but preserved the tonal balance of the speaker.
I have not listened to a ton of speakers in my life, and I would not trade the Nova 6s with my current A25s, but for Radio Shack speakers that I got for basically nothing and fixed for little money, I'm impressed, they are smooth and very enjoyable, I'm very happy about them.
So my final recommendation if you replace the Nova 6 tweeters with the Goldwood GT-25s is to add a 5 ohms (or so) 5W+ resistor in series with the tweeters to tame them down a little bit, and listen to result.

Thanks for the follow up. Glad to hear you got those tweeters dialed in.
I've kept the Optimus 2B's I have, same as the Nova's 6's, for years. They really are a nice sounding small speaker.
The original tweeters are still good in mine, but I did replace the crossover caps. I have thought about adding a coil to the woofers though since they run full range. Forcing the woofer to roll off at the crossover point should tighten up the bass some along with the lower midrange. Adding a coil to the woofers in my Nova 7B's really made a difference for the better.

 

[Old-School]

Nice work. I'm a big fan of the Goldwood GT-25's. Nice little speakers for not much money.

 

[Jim121362]

OK I received the GT-25 tweeters this morning. I first installed only one so I could compare with the original.
For the record, they fit the tweeter opening nicely in the Nova 6, I was even able to fit it in the "plastic cup" that's behind the original tweeter, although it is not really needed as the GT-25 has a closed/sealed back. However, the GT-25 doesn't match the original screw holes. The original tweeter is mounted with 4 bolts and metal inserts in the cabinet. I didn't want to go through getting the metal inserts out and reinstall them to fit the GT-25, I simply rotated the GT-25 45degrees, drilled pilot holes and use wood screws. Also, the spade connectors on the GT-25 are larger than the original so I soldered new ones on the wires. I saw a comment somewhere that there is no polarity indication on the GT-25, in fact there are plus and minus signs stamped on the small "cardboard" just beside the terminals, there are hard to spot but they are present.
So I fired up the beloved KA-4002 and played some music.
The GT-25 certainly add a bit of "sharpness" or "crispness" (audiophile technical terms here... ) to the Nova 6s. But not in an unpleasant way. In fact, setting up the amp in mono, I could not hear a huge difference between the GT-25 and the original tweeter. I was concerned the GT-25's sensitivity would be much greater than the original, but in fact if one the tweeters sings louder, it's the original. And that's a big 'if', they are matched quite well.
So I installed the GT-25 in the other cabinet and tested again. Again, it feels like they go higher, but they are high frequencies that should be there anyway. They are not overly strong or fatiguing, the speakers are not "shouty", the tweeters blend nicely with the woofers, and I did not have to play with the tweeter level switches (kept them in Normal). Keep in mind I'm 59, worked all my life in a noisy environnment, I can't hear much above 12K and almost nothing from 14K!! They still don't beat my Dynaco A25XL, but to me, with the GT-25s the Nova 6s stays balanced and pleasurable, they are a VERY close match to the original tweeters and a GOOD replacement for them.
The Nova 6 pairs nicely with the old Kenwood, and my daughter, who is less than half the age of her new stereo, is happy too!
Next step is replacing the old electrolytics in the crossover.

Question about your original NOVA 6 tweeters: Were the surrounds on the tweeters kind of an open mesh that, if you look closely, you can see through? Or was there some doping there that has disintegrated? I have a pair of Nova 6s that sound great, but I'm wondering if the tweeters are in original condition with the mesh surrounds or if they have disintegrated over the years? Thanks.