Hi there. My Ninka's have blown up but I can't bear to throw them out so I want to replace the drivers. I have sourced some Vifa P17WJ-00-08 and will get some Hiquphon OW-1 with a rebuild of the crossover. (This is my first foray into DIY Audio). My first challenge is tracing the FRD and ZMA. I have tried tracing programs but I can't seem to get the impedance curve to behave. It is wildly off. Does anyone have FRD and ZMA files for the speakers above? I am getting quite frustrated with my tracing efforts.
Thanks in Advance.
Mike
Thanks in Advance.
Mike
Are you sure they're 'blown up'? It could just be a loose connection, a dud component in the crossover etc so I'd look at those issues before I spend $$ on different drivers and crossovers.
Do you have measuring equipment? I ask because I understand that FRD and ZMA files for a driver will vary with the cabinet size. So, while the VIFA has been used in many DIY projects, the cabinet details and the measurements will probably differ from your speakers.
I also use tracing programs (usually fptrace), but their usefulness depend on the accuracy of the graphs provided by the maker and they're usually not measured in-box. Better than guesswork, but.
I assume you want to do as little surgery as possible to those nice cabinets, so assume the Vifas match the existing woofer cut-outs? Do the Hiquiphon tweeters also fit?
In your position, I'd do a google search for 'VIFA PW17 MTM speakers' and see what comes up. You might be able to find a project which uses those woofers and compare its cabinet measurements with yours. Even if they're not exactly the same, you might get close, for example: . Pre-Assembled Vifa JV60 Speakers | Jaycar Electronics
Geoff
Do you have measuring equipment? I ask because I understand that FRD and ZMA files for a driver will vary with the cabinet size. So, while the VIFA has been used in many DIY projects, the cabinet details and the measurements will probably differ from your speakers.
I also use tracing programs (usually fptrace), but their usefulness depend on the accuracy of the graphs provided by the maker and they're usually not measured in-box. Better than guesswork, but.
I assume you want to do as little surgery as possible to those nice cabinets, so assume the Vifas match the existing woofer cut-outs? Do the Hiquiphon tweeters also fit?
In your position, I'd do a google search for 'VIFA PW17 MTM speakers' and see what comes up. You might be able to find a project which uses those woofers and compare its cabinet measurements with yours. Even if they're not exactly the same, you might get close, for example: . Pre-Assembled Vifa JV60 Speakers | Jaycar Electronics
Geoff
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Hi Geoff,
The original speakers don't move anymore, and there is no ohm reading on the speakers. Thanks for the advice on FRD and ZMA files. The Vifas are 'drop in' replacements for the existing drivers and Hiquphon have the 3/4" plate to fit the Ninka tweeter pattern. So in this case I think the next plan is to acquire a calibrated microphone and take some measurements. A gentleman in another forum mentioned that the Vifa's give an excess capacity in the case of 5.79L so I plan to pop some 90x45 blocks in there to take up the excess capacity. Then take a look at the crossover. Cheers, Mike
The original speakers don't move anymore, and there is no ohm reading on the speakers. Thanks for the advice on FRD and ZMA files. The Vifas are 'drop in' replacements for the existing drivers and Hiquphon have the 3/4" plate to fit the Ninka tweeter pattern. So in this case I think the next plan is to acquire a calibrated microphone and take some measurements. A gentleman in another forum mentioned that the Vifa's give an excess capacity in the case of 5.79L so I plan to pop some 90x45 blocks in there to take up the excess capacity. Then take a look at the crossover. Cheers, Mike
Hi Geoff, not sure if the previous message made it through. The speakers are cooked. No ohm reading on anything. I had a short in my Rega Elex-r amp and it wasted the speakers at about 9 oclock on the volume dial, real low. The Vifa and Hiquphon OW-1 are 'drop in' replacements and will just fit in the Ninka's. From what you say it sounds like it would be best to buy/borrow/rent a calibrated microphone and take the measurements to get the real values. I have to knock down the size of the internals by ~5 Litres to get the Q closer to .707 (another gentleman helped me with that). Cheers, Mike
I've done my own traces for FRD and MA from the makers' data, I'm happy to have a go in Xsim and give you something which you could post up for other far more knowledgeable than me to critique.
Geoff
Geoff
Awesome. That would be a great help. I just kid of wanted to see what the factory crossover would look like before I go too berserk on ripping the crossover to pieces. Cheers
One issue with matching that tweeter with the Vifas is their relatively low (official) output of 88dB; most tweeters are at 90-92dB. The Vifa official output is 88dB, so if you have two in parallel that gives you +6 dB, i.e. 94.
Allowing for (say) 3dB Baffle Step Compensation, that still gives you a bit of a mis-match between the drivers' output: that's why it's so important to measure drivers rather than rely on the 'official' graphs. I'll see what I can come up with but it's not going to be very accurate.
Geoff
Allowing for (say) 3dB Baffle Step Compensation, that still gives you a bit of a mis-match between the drivers' output: that's why it's so important to measure drivers rather than rely on the 'official' graphs. I'll see what I can come up with but it's not going to be very accurate.
Geoff
Hi Geoff, thanks for that. There is an alternative tweeter that might be a better match. It’s this one ScanSpeak Classic D2008/8512 20 mm Dome Tweeter it’s got a db rating of 88. Would that be a better choice? Cheers, mike
Do the Ninka's use 8Ω (nominal) bass units? I see some of them listed as 4Ω. The inverse roll surround seems quite "SEAS" to me btw, those had 1" voice coils, whereas the Vifa P17WJ have the 1 1/4" coils. Are you aiming at reconfiguring the crossover?
Hi, yes the Ninka’s run at 4ohm but run 8ohm in parallel for the woofers and tweeters. The reconfiguration of the crossover is also part of the undertaking. It’s actually quite nifty as a side note. Depending on the plate selected (single wire, no-wire, tri amp. There is a circuit layout on the card and it creates links between different posts to achieve the correct crossover configuration! However I will simplify down to either single wire or bi wire passive.
That's a very expensive tweeter, I wouldn't be using it as it would need an experienced crossover designer to do it justice - certainly not me!
Did you have any luck with a Google search on Vifa P17W MTMs?
Have tried an Xsim model but the tweeter response over 10k is wonky for some reason, so I won't post just yet.
Geoff
Why not re-coil the original drivers? Unfortunately SpeakerBits in Melbourne seems to be defunct, as does Recoil in Sydney, but Queensland Speaker Repairs in Brisbane and Southern Audio Repairs in Adelaide are still going. Richard at SAR is the voice coil guru. It is usually possible to install voice coils made with high temperature Katpton formers with the same parameters as the originals, which gives a boost to the system power rating at the same time, and cheaper than replacements of original or equivalent drivers.
Here's a thought: you could contact pheonix358 on this forum, he designed the Jaycar speakers referenced above and might have some tweeter suggestions.
Worth a try?
Geoff
Worth a try?
Geoff
These are awesome ideas. Thanks a bunch chaps! I might see if the coils can be fixed. i'll get back shortly! I'll also reach out to the other member. There are very few 92mm tweeters that fit the hole, so the Hiquphon and Scanspeak D2008 were my primary choices due to fit but if that can be sorted, I am open to others.
cheers, Mike
cheers, Mike
Don't fix the coils as long as you haven't checked the condition of the roll surrounds. The repair shop will tell you this too, I reckon.
OK, I have dropped the speakers off at Total Recoil in Fawkner here in Melbourne. I'll keep you all posted as to the outcome! Cheers, Mike