Nova 6 tweeter options (revisited, again)

[CarlQB]

In the process of building a small vintage sound system for my daughter so she can listen to music with something else than her beer-can-size BT speaker (or directly from her cell phone) I bought a pair of Realistic Nova 6 speakers for $20. The cabinets are in VERY good condition, not a nick, sharp corners, etc.
The issue is one of the tweeters has been replaced by a previous owner. I don't know the brand of the tweeter they put in but I can say that it doesn't sound as good as the original one in the other cabinet. I think this replacement tweeter doesn't go as low as the original, and there is something missing in the upper mids (crossover frequency is apparently around 2200hz). It's not too obvious in casual listening, but when paying attention and playing with the balance control to compare, there is definitely a difference between both speakers, the original one seems "fuller" (sorry for the audiophile technical term!) and I like it much better.
The original tweeter is an 8 ohms 3" cone paper model 0735, Freq response from 300hz (!) to 18kHz, 5W nominal 10W max. They are known for being somewhat fragile, and I also know that the only Realistic speakers to use this specific tweeter are the Nova 6 and Optimus 1B (same speakers basically), so they are quite rare in the used market (I can't find any right now).
I'm not the first one to look for Nova 6 tweeter replacements, there are a few threads on AK about it (some more than 15 years old), and after reading through much of them I came up with quite a few options, which kinda confused me a bit, and that's why I'd like to revisit the subject and hear about opinions from those who have experience with the suggested tweeters.
Bear in mind: I'm in Canada (shipping from the US can be super expensive), I'm on a limited budget (paid the speakers $20, I don't want to pay $50 for a tweeter), I don't expect the Nova 6 to turn into Advents or Dynacos, but I'd like to get the sound at least as good as the originals, without the upper mids drop I'm currently having. I'd like to replace both tweeters so both speakers sound balanced, I don't want to rebuild/modify the crossover (which is a single cap that I will replace), and I'd prefer a drop in replacement (no cabinet mod/cutting).
Options are:

1- Goldwood GT-25 3" paper cone. 8 Ohms, 40W. 1.5kHz-21kHz, Fs: 1kHz, Sensitivity 96dB. About $10.
I don't know the sensitivity of the OEM tweeter but it seems to me 96dB is quite high and I fear it would be too much.

Goldwood GT-25 - 8 ohm 3" 40W Home Stereo Cone Tweeter

3" paper cone tweeter. SPECIFICATIONS Nominal Diameter: 3.0", 76mm Nominal Impedance: 8 ohms Power: 40 W rms Freq. Response: 1.5 kHz-21 kHz Sensitivity: 96 db 1w/1m Magnet Weight: 3.0 oz, 85 grams Voice Coil Diameter: 0.56", 14mm Min. X-over: 1.5 kHz/12dB MOUNTING INFORMATION Overall Diameter...

qcomponents.ca

2- Goldwood GT-302 2.5" dome, 8 Ohms, 75W, 4kHz-19kHz, Fs: 2Khz, 92 dB. $7.
(FWIW, this tweeter was actually suggested as one of the 'best option' by ChatGPT !!)

Goldwood GT-302 - 8 ohm 2.5" 75W Home Stereo Dome Tweeter

14 mm polymer dome tweeter. SPECIFICATIONS Nominal Dimension: 2.5x2.5", 61x61mm Nominal Impedance: 8 ohms Power: 75 W rms Freq. Response: 4 kHz- 19 kHz Sensitivity: 92 db 1w/1m Magnet Weight: 1 oz, 28 grams Voice Coil Diameter: 0.51", 14mm Min. X-over: 4 kHz/12dB MOUNTING INFORMATION Overall...

qcomponents.ca

3- "Avalanche" brand dome tweeter from Maddison (electronic part stores in Canada). 8 Ohms, 20W, 2kHz-20kHz, Fs: 2Khz, 90dB. $10, made in China, specs quite close to OEM I think.

Haut-parleur de haute fréquence 8 ohms – 10W RMS |

Haut-parleur de haute fréquence. Impédance: 8 ohms. Puissance de 10W RMS. Puissance maximale de 20W Peak. Fréquence: 2 000 Hz à 20 kHz. Sensibilité: 90 dB. Diamètre: 3-3/8" Diaphragme (Voice coil): 0.5". Aimant: 1.35 oz..

www.maddison.ca

4- Dayton DC25T-8 Titanium dome, 8 Ohms, 50W, 3kHz-20kHz, Fs: 1468Hz, 93dB. $27 (getting expensive!) One member here (@uxwbill) has used these for his Nova 6s, there is a thread on AK about it and he made a YT video.

DC25T-8

Dayton Audio DC25T-8 (1in) Titanium Dome Tweeter, 8 ohm, 100mm Faceplate

solen.ca

5- PRT-8 Phenolic Ring tweeter replacement for vintage CTS tweeters. 8 Ohms, 30W, 2kHz-18.5kHz, Fs: 1005Hz, 90dB. $31 (expensive).

PRT-8

GRS PRT-8, 19mm (0.75in / 3/4in) Phenolic Ring Tweeter Replacement for AR-4X CTS Marantz and More 8 Ohm, 107mm Faceplate

www.solen.ca

Some have suggested using small, full range drivers like this one. I don't how how this would sound (there are other full range options but they are even more expensive):

6- PC83-8 Full Range Poly Cone driver, 8Ohms, 30W, 80Hz-20kHz, Fs 82Hz, 85.6dB, $28.

PC83-8

Dayton Audio PC83-8, 83mm (3in) Full-Range Poly Cone Driver, 8 ohm

www.solen.ca

I'm also open to other options, vendors, etc.

Thanks!

 

[Lavane]

I have a pair of Optimus 2B's that are the same as the Nove 6's except for cosmetics.
The Goldwood paper cone tweeters should work if they will fit.
I have a pair of them in a parts bin. I did an A/B test between them and some CTS Phenolic ring tweeters in a pair of Marantz Imperial 6 speakers.
I really couldn't hear much if any of a difference. For a cheaper paper cone tweeter the Goldwoods sound pretty good.
Of course a soft dome may sound better. Probably smoother with better detail. Silk, doped cloth, etc for dome tweeters. I've always found metal and mylar domes to sound kind of sharp, or harsh sounding.
The 8 ohm reproduction phenolic ring tweeters Parts Express sells would probably sound good also. I really like them in the Marantz Imperial 5's and 6's.

 

[CarlQB]

Thanks Lavane for the feedback, especially on the Goldwood paper cone.
If budget wasn't limited I'd opt for the phenolic ring tweeter, but with shipping here they come up to about $86, more than twice the price of the Goldwood. I need to consider fitment in the existing hole also. Ii don't want to enlarge the hole unless I have to.

 

[CarlQB]

I took out the replacement tweeter the previous owner installed.
It is a Kenwood TO3-464-05.
I couldn't find specs for it, but I saw it is used in some Kenwood large 3-way speakers. Specs for these speakers show this tweeter crossover freq at 5000hz.
No doubt very inappropriate in a 2-way design with a low crossover point like the Nova 6s. No wonder I hear a dip in upper mids, this tweeter probably doesn't even reach down to the Nova's xover point.

As a reference, the tweeter opening hole in the Nova 6 cabinet is slightly over 3 inches, like 3" 3/32. The inner diameter of the plastic cub (seal) the tweeter sits in is about 2.75 ".

 

[Lavane]

P.E. should have the measurements specs. In the description.
There is usually 2 tabs in the description. The second tab should give measurement specs. If not I can measure one for you when I get home later.

 

[CarlQB]

Yes I found the GT-25 requires a 78mm hole, which is exactly the size of the Nova 6 opening. So they would fit.
However, the OEM tweeter sat in a plastic "cup", to seal it from the woofer. Otherwise, since the Nova 6 is a sealed enclosure, I guess air pressure from the woofer could have affected (or blown) the OEM tweeter membrane. Now I'm looking at this GT-25 and wonder if it is sealed/protected by design, or if the "cup" (or similar air barrier) would be required. The inner diameter of the Nova's "cup" is smaller than the GT-25 by about 1/4in, it wouldn't fit.
I sent a message to QComponents, the canadian reseller of the GT-25 about this. (Edit: they responded almost immediately, the tweeter has a closed back and unnafected by the woofer's pressure, so it's apparently not an issue).

 

[Ed240]

In the process of building a small vintage sound system for my daughter so she can listen to music with something else than her beer-can-size BT speaker (or directly from her cell phone) I bought a pair of Realistic Nova 6 speakers for $20. The cabinets are in VERY good condition, not a nick, sharp corners, etc.
The issue is one of the tweeters has been replaced by a previous owner. I don't know the brand of the tweeter they put in but I can say that it doesn't sound as good as the original one in the other cabinet. I think this replacement tweeter doesn't go as low as the original, and there is something missing in the upper mids (crossover frequency is apparently around 2200hz). It's not too obvious in casual listening, but when paying attention and playing with the balance control to compare, there is definitely a difference between both speakers, the original one seems "fuller" (sorry for the audiophile technical term!) and I like it much better.
The original tweeter is an 8 ohms 3" cone paper model 0735, Freq response from 300hz (!) to 18kHz, 5W nominal 10W max. They are known for being somewhat fragile, and I also know that the only Realistic speakers to use this specific tweeter are the Nova 6 and Optimus 1B (same speakers basically), so they are quite rare in the used market (I can't find any right now).
I'm not the first one to look for Nova 6 tweeter replacements, there are a few threads on AK about it (some more than 15 years old), and after reading through much of them I came up with quite a few options, which kinda confused me a bit, and that's why I'd like to revisit the subject and hear about opinions from those who have experience with the suggested tweeters.
Bear in mind: I'm in Canada (shipping from the US can be super expensive), I'm on a limited budget (paid the speakers $20, I don't want to pay $50 for a tweeter), I don't expect the Nova 6 to turn into Advents or Dynacos, but I'd like to get the sound at least as good as the originals, without the upper mids drop I'm currently having. I'd like to replace both tweeters so both speakers sound balanced, I don't want to rebuild/modify the crossover (which is a single cap that I will replace), and I'd prefer a drop in replacement (no cabinet mod/cutting).
Options are:

1- Goldwood GT-25 3" paper cone. 8 Ohms, 40W. 1.5kHz-21kHz, Fs: 1kHz, Sensitivity 96dB. About $10.
I don't know the sensitivity of the OEM tweeter but it seems to me 96dB is quite high and I fear it would be too much.

Goldwood GT-25 - 8 ohm 3" 40W Home Stereo Cone Tweeter

3" paper cone tweeter. SPECIFICATIONS Nominal Diameter: 3.0", 76mm Nominal Impedance: 8 ohms Power: 40 W rms Freq. Response: 1.5 kHz-21 kHz Sensitivity: 96 db 1w/1m Magnet Weight: 3.0 oz, 85 grams Voice Coil Diameter: 0.56", 14mm Min. X-over: 1.5 kHz/12dB MOUNTING INFORMATION Overall Diameter...

qcomponents.ca

2- Goldwood GT-302 2.5" dome, 8 Ohms, 75W, 4kHz-19kHz, Fs: 2Khz, 92 dB. $7.
(FWIW, this tweeter was actually suggested as one of the 'best option' by ChatGPT !!)

Goldwood GT-302 - 8 ohm 2.5" 75W Home Stereo Dome Tweeter

14 mm polymer dome tweeter. SPECIFICATIONS Nominal Dimension: 2.5x2.5", 61x61mm Nominal Impedance: 8 ohms Power: 75 W rms Freq. Response: 4 kHz- 19 kHz Sensitivity: 92 db 1w/1m Magnet Weight: 1 oz, 28 grams Voice Coil Diameter: 0.51", 14mm Min. X-over: 4 kHz/12dB MOUNTING INFORMATION Overall...

qcomponents.ca

3- "Avalanche" brand dome tweeter from Maddison (electronic part stores in Canada). 8 Ohms, 20W, 2kHz-20kHz, Fs: 2Khz, 90dB. $10, made in China, specs quite close to OEM I think.

Haut-parleur de haute fréquence 8 ohms – 10W RMS |

Haut-parleur de haute fréquence. Impédance: 8 ohms. Puissance de 10W RMS. Puissance maximale de 20W Peak. Fréquence: 2 000 Hz à 20 kHz. Sensibilité: 90 dB. Diamètre: 3-3/8" Diaphragme (Voice coil): 0.5". Aimant: 1.35 oz..

www.maddison.ca

4- Dayton DC25T-8 Titanium dome, 8 Ohms, 50W, 3kHz-20kHz, Fs: 1468Hz, 93dB. $27 (getting expensive!) One member here (@uxwbill) has used these for his Nova 6s, there is a thread on AK about it and he made a YT video.

DC25T-8

Dayton Audio DC25T-8 (1in) Titanium Dome Tweeter, 8 ohm, 100mm Faceplate

solen.ca

5- PRT-8 Phenolic Ring tweeter replacement for vintage CTS tweeters. 8 Ohms, 30W, 2kHz-18.5kHz, Fs: 1005Hz, 90dB. $31 (expensive).

PRT-8

GRS PRT-8, 19mm (0.75in / 3/4in) Phenolic Ring Tweeter Replacement for AR-4X CTS Marantz and More 8 Ohm, 107mm Faceplate

www.solen.ca

Some have suggested using small, full range drivers like this one. I don't how how this would sound (there are other full range options but they are even more expensive):

6- PC83-8 Full Range Poly Cone driver, 8Ohms, 30W, 80Hz-20kHz, Fs 82Hz, 85.6dB, $28.

PC83-8

Dayton Audio PC83-8, 83mm (3in) Full-Range Poly Cone Driver, 8 ohm

www.solen.ca

I'm also open to other options, vendors, etc.

Thanks!

You could go with a Markaudio CHN-50P full range. Markaudio CHN-50P 3" Paper Cone Full Range | Madisound This Dynavox metal dome has a cover and is one I've used when making the Nova-6/Optimus-2B a 3-way https://www.newark.com/multicomp-pro/53-5165/1-large-flange-aluminum-dome-tweeter/dp/84Y8044

 

[CarlQB]

You could go with a Markaudio CHN-50P full range. Markaudio CHN-50P 3" Paper Cone Full Range | Madisound This Dynavox metal dome has a cover and is one I've used when making the Nova-6/Optimus-2B a 3-way https://www.newark.com/multicomp-pro/53-5165/1-large-flange-aluminum-dome-tweeter/dp/84Y8044

Looks like a good option! Thanks!
But I'm in Canada, I haven't seen a canadian distributer, and the shipping fees and exchange rate are killing me. They come up to $118 at my door.
Right now I have the Goldwood GT-25 on order ($38 delivered from QComponents in Canada), I'm confident they will do the job just fine. I will compare with the OEM and post back my impressions.

 

[Lavane]

You may find the GT-25's a bit more dynamic sounding? The tweeters used in some RS speakers tended to sound a bit layed back to me.
The Optimus 2B's and Nova 6's being an example of that.

 

[CarlQB]

I don't know, I can't wait to check them out. I don't mind being more dynamic, as long as they don't get too "shouty". I will replace only one to begin with and compare with the (only) original tweeter I have. There is always the Hi/Low/Norm switch in the back I can play with, and also the resistors in the crossover can be changed for different values.

 

[Lavane]

I don't think they'll be harsh or shouty. There are resistors in the crossovers, and the switch to attenuate the tweeter as you stated. I was surprised at how well these
G-25 tweeters sounded. The soeakers I tried them in just had the one resistor, no switch.
I had a pair of Nova 4's, they were very shouty. To the point I couldn't listen 5o them. They had cbeap paper cone tweeters with only a capacitor for a crossover. The woofer ran full range. I put crossovers that crossed over at the same frequency as that capacitor and put them in the speakers along with sof5 dome tweeters from donor speakers. With now having a coil to roll off the woofer, and a cap and resistor for the tweeter those Nova 4's sounded pretty decent. I took the crossovers from another small pair of Realistic speakers with blown 4" woofers.

 

[Bodyblue]

I don't think they'll be harsh or shouty. There are resistors in the crossovers, and the switch to attenuate the tweeter as you stated. I was surprised at how well these
G-25 tweeters sounded. The soeakers I tried them in just had the one resistor, no switch.
I had a pair of Nova 4's, they were very shouty. To the point I couldn't listen 5o them. They had cbeap paper cone tweeters with only a capacitor for a crossover. The woofer ran full range. I put crossovers that crossed over at the same frequency as that capacitor and put them in the speakers along with sof5 dome tweeters from donor speakers. With now having a coil to roll off the woofer, and a cap and resistor for the tweeter those Nova 4's sounded pretty decent. I took the crossovers from another small pair of Realistic speakers with blown 4" woofers.

Good GOD those were horrible!

 

[Bodyblue]

I don't think they'll be harsh or shouty. There are resistors in the crossovers, and the switch to attenuate the tweeter as you stated. I was surprised at how well these
G-25 tweeters sounded. The soeakers I tried them in just had the one resistor, no switch.
I had a pair of Nova 4's, they were very shouty. To the point I couldn't listen 5o them. They had cbeap paper cone tweeters with only a capacitor for a crossover. The woofer ran full range. I put crossovers that crossed over at the same frequency as that capacitor and put them in the speakers along with sof5 dome tweeters from donor speakers. With now having a coil to roll off the woofer, and a cap and resistor for the tweeter those Nova 4's sounded pretty decent. I took the crossovers from another small pair of Realistic speakers with blown 4" woofers.

Good GOD those were horrible!

 

[Lavane]

Good GOD those were horrible!

Yes they were. They gave me ear fatigue immediately. I used the soft dome tweeters and crossovers from those small metal speakers with rotted surrounds on the woofers you gave me. The crossover point was the same as the Nova's 4's. They sounded pretty good after. Decent controlled bass, good midrange and smooth detailed highs. My oldest son is using them with a small Realistic receiver. He isn't into HiFi really, he just uses the tuner for a source. He made an indoor antenna that works really well.

 

[CarlQB]

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.

 

[CarlQB]

Just did the recap. I replaced the electrolytics with films. Interestingly, in one of the speakers someone had been there before me. The cap wasn't original, and had been replaced with another electroytic, but a 2.2uF (required value is 4.7uF). I guess he didn't have any bipolar 4.7s around on that day.
I had to reinstall the new tweeters. The screw holes of ther GT-25 didn't match the originals, and the cabinets were not air tight. When slightly pressing down on the woofer membrane, I could hear some whistling air noise around the tweeters and the mounting holes. So I took the "plastic cups" out, fabricated new tweeter seals with some thin packaging protecting foam, and plugged the old holes. That worked nicely.
I "deoxited" the rear switches and gave them a good workout. I thought about adding internal braces in the cabinet, but decided this could be done at a later time (wood shop is not heated in the winter, and it's like -15 right now!) and I'm not sure it's worth the effort.
All is left is the cosmetic part, but the cabinets are already almost perfect, I'll just clean the lattice grilles and probably replace the old brown fabric.
Along with the KA-4002, this little stereo system is a sleeper. The small amp doesn't look like much, and people usually don't expect much from old-looking speakers lattice grilles from the 70s, especially with a Radio-Shack logo on them. I know some will be surprised!!

 

[Lavane]

Nice work! For a small sealed speaker cabinet with an 8" woofer the bass is surprisingly good in those speakers too. Good call on checking for air leaks.
It's such a small cabinet, I'm not sure bracing would really be needed.
But its nice to know the G-25's work very well with these speakers too.
I use my Optimus 2B's with one of the small tube systems I have setup around my bench. They're nice for near field listening too.
Did you notice any difference with new caps? I can't say I did, but the originals were very common general purpose caps, and they were getting long in the tooth for an electrolytic cap.
Post a picture of one of the speakers with the new tweeter.

 

[CarlQB]

I can't say the new caps changed the sound a lot. The original 4.7 measured 5.25uF, and the 2.2 was close to specs.
They might sound a bit more defined, but could be my imagination!
Photo with the old cap. I put a piece of cardboard in front of the new tweeter (actually the protection box the tweeter came with).

 

[CarlQB]

Just a temporary setup in my basement.

 

[Bodyblue]

The Nova 6 is one of my favorite RS speakers. Just like the 7Bs and 8Bs, they need to be kicked in the ass a bit to really perform. And just like those, the 6s can get really freaking loud without distorting. Like @Lavane said above, they bass is rather astounding for their size. About 10 years ago I got a set of Small Advents to see for myself if the performance was as good as people on here said. I had them for a few months and was impressed by the bass. Then I got my first set of Nova 6s. Going toe to toe, the Nova's bass was so close, it was a wash and I thought the Novas sounded better on the high end. Add to the fact that Small Advents only had a crappy vinyl wrapped cabinet and Novas all have the beautiful walnut veneer, that means the Advents moved on. AND the Novas sound as good as they do and are 8 ohm is even more impressive.