first time speaker builder

I have nice 25 year old 2-way speakers that i want to replace the drivers. They are "8 ohm". I have purchased the 8-inch replacement woofers and they are 8 ohms, but I cannot find what I want in an 8 ohm tweeter. I found a tweeter I want that is 4 ohms. Can I use a 4 ohm tweeter with an 8 ohm woofer? Would I end up with "6 ohm" speakers?
 

Galu

Member
2018-04-17 6:50 pm
It is not generally a good idea to substitute original drivers with a set of 'randomly' selected replacement drivers.

However, in answer to your questions, you can use a 4 ohm tweeter with an 8 ohm woofer, but the crossover circuit has to be redesigned - your existing crossover is unlikely to match.

Using an 8 ohm woofer means you will end up with an overall speaker impedance of 8 ohm - the crossover network ensures that the woofer and tweeter are not electrically in parallel as they operate over different frequency ranges.

If you supply more information about your 25 year old speakers and the intended driver replacements, more help may be forthcoming.
 
Thanks for your reply. These were mid-fi to begin with. Crossover is 2500. Don't know who made the woofers but the replacements I bought are Silver Flute 8" W20RC38's, 91dB. The tweeters were Audax HD100D25's. The tweeters I want are the Peerless DA25BG08-08 but everyone is out of stock and min. order quantity is 1000 so no one is re-ordering. They do have it in 4 ohms, the DA25BG08-04, 92dB, resonant frequency 770Hz. Perhaps the better question that eliminates the crossover issue, is what tweeter, in 8 ohms, will match up nicely with the Silver Flutes? Thanks.
 

Galu

Member
2018-04-17 6:50 pm
Perhaps the better question that eliminates the crossover issue, is what tweeter, in 8 ohms, will match up nicely with the Silver Flutes?
You should be aware that there's more to crossovers than simply ensuring that both drivers are 8 ohm types.

Any new bass/mid and tweeter combination will require a crossover tailored to all their published specifications if the drivers are to blend properly.

In addition, have you thought about whether the internal volume and type (sealed or ported) of the old enclosure matches the parameters of the Silver Flutes?

More details of the enclosure would be nice i.e. photos/dimensions.

Then, hopefully, someone with experience of your Silver Flutes will chime in with suggestions.
 
Looks like the Audax tweeter was 5.8 ohms DCR and 89dB soft dome on 100mm plate.

100mm is always a bit awkward if the rebate is already done. But SB Acoustics do them in the here preferred metal style:

SB26ADC-C000-4 :: SB Acoustics

That's 90dB 3,2 ohm DCR.

SB26ST-C000-5 :: SB Acoustics

That's 91dB 4.4R DCR, but a soft dome.

All looks doable to me... time will tell, as you say. :)
 

boswald

Member
Paid Member
2014-06-27 3:32 pm
The Audax is still a fine tweeter(if no longer fashionable in appearance), the Peerless adds nothing but supersonic peaks which might bother your dog, if using certain analog sources.

It's very easy to replace old ferrofluid in the Audax, if dried and making trouble.
 
I think you'll find the only Peerless Da25BG that is available and not MOQ, is the 6 ohm variant:
Peerless DA25BG08-06 1" Aluminum Dome Tweeter 6 Ohm

I've used it, and it's a great tweeter. It's also pretty sensitive or higher initial output, and will likely need resistor padding changes to balance out the midbass to tweeter levels. I advise placing a 30 ohm resistor across it to minimize the Fs spike and avoid nasal sounding lower treble range.

Later,
Wolf
 
Well, I'm a little overwhelmed. Thank you for your replies and interest. The speakers are the BIC V820's from about 1994. Don't laugh, they always sounded good to me and were right sized. I have owned other speakers since that time but these are the ones I never parted with. I blew a woofer some years ago. Now, I just want to replace the woofers with something as good or better and better tweeters if possible and by that I mean at a reasonable cost. A picture is attached. The Silver Flutes are installed. They are vented in the rear with a slot about 1" tall running the entire width at the bottom. I would like to know if there is an already assembled crossover that would match the Silver Flutes up to the tweeters. I may consider keeping the tweeters I have but they do need fluid so I will need to know how to do that if I keep them. I am also willing to consider a custom crossover(s) built by one of you if affordable, shipped to Kentucky.
 

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Galu

Member
2018-04-17 6:50 pm
The speakers look very nice.

In order not to spoil their looks, wouldn't you want a replacement tweeter with a rectangular face plate the same size, or larger, than the present one so that the original fixing holes will not be exposed to view?

If you measure the dimensions of the faceplate and the diameter of the mounting aperture in the enclosure, we may come up with a cosmetically friendly replacement.

I presume you are happy with the bass/mid performance of the Silver Flutes in this ported cabinet?
 
Looked into that. The Venturi faceplate was proprietary and mounted to the Audax tweeter with the centerline for the connections at 7:30 and the connectors at 7 and 8 o'clock. The new Audax that is the replacement has connectors opposed to each other at 12 and 6 or 3 and 9 depending on how you mount it and will not mount to this faceplate. I can get the new Audax but will have to use the Audax faceplate and lose the Venturi logo. And re-bore the holes to accommodate the connector locations (make them wider for the new 3 and 9 o'clock connectors). I'd rather just re-fluid the existing ones and keep them than do that. Yes, I will have to suffer with four unused screw holes in the faces if I go to new different tweeters but an improvement in high fidelity would be worth it to me.