Replacement drivers for Wharfedale Chevin XP

[Sicaris]

My parents have a pair of Wharfedale Chevin XP speakers which were paired with a Rotel RA-312 amplifier (about 18w into 8 Ohms). The Rotel is still working well but the speaker cones have degraded completely.

The specs page is here: https://m.hifidatabase.com/Wharfedale_Chevin XP_6138.php

And the Rotel: https://www.hifiengine.com/manual_library/rotel/ra-312.shtml

My dad would like to get some replacement drivers (8" full range) which feels like it shouldn't be too difficult (no crossover to deal with) but other than knowing the cabinet size (11 L) and sensitivity (89 db) I don't know how to go about selecting something appropriate.

I'm not sure how high quality these were to begin with but for sentimental reasons it would be nice to get them working instead of just replacing with something new.

Any suggestions for drivers or how to go about selecting some?

Thanks!

 

[RickS]

SB Acoustics has a newer 8 inch full range that is reasonably priced.

Would need to know the exact cut-out hole size to see if it might fit.

 

[Sicaris]

Excellent, thank you. Is this the one you're talking about: https://sbacoustics.com/product/8in-sb20frpc30-8-paper/

I can see this has a reasonable frequency response according to their data. It seems to be more sensitive into the same load so should be louder for a given volume, is that correct? Are there any other factors to consider like the relatively small size of the cabinet with no port?

Thanks again!

 

[DVDdoug]

It seems to be more sensitive into the same load so should be louder for a given volume, is that correct?

Correct!

Are there any other factors to consider like the relatively small size of the cabinet with no port?

"Random" sealed cabinets are more forgiving than ported cabinets which can turn-out "badly tuned" if the driver is mismatched to the tuning.

You can plug the driver's Thiele-Small Parameters and cabinet volume into speaker design software to predict performance. (You could even experiment virtually with adding a port and the software will help to optimize port dimensions.) WinISD is FREE!

 

[RickS]

Excellent, thank you. Is this the one you're talking about: https://sbacoustics.com/product/8in-sb20frpc30-8-paper/

I can see this has a reasonable frequency response according to their data. It seems to be more sensitive into the same load so should be louder for a given volume, is that correct? Are there any other factors to consider like the relatively small size of the cabinet with no port?

Thanks again!

Yes, it is a little borderline for as small an enclosure so might benefit from some added damping material. However, matters less if it does not fit well. There are other drivers and likely one that works better in sealed box. Unless you are willing to resize the cutout, it is the first hurdle for any replacement driver.

Do you have a budget target for this project?

 

[Sicaris]

Correct!


"Random" sealed cabinets are more forgiving than ported cabinets which can turn-out "badly tuned" if the driver is mismatched to the tuning.

You can plug the driver's Thiele-Small Parameters and cabinet volume into speaker design software to predict performance. (You could even experiment virtually with adding a port and the software will help to optimize port dimensions.) WinISD is FREE!

Thank you for the suggestion, I have downloaded WinISD and input the parameters I can find from the SB Acoustics site. With a sealed 11L cabinet I get the frequency response below. If anything looks glaringly wrong in the parameters please let me know.

It seems like these would have a bit too much upper bass and would drop off quite quickly in the low frequencies. I suspect there's not much to be done about the low frequency drop off (plus I don't think my parents will mind as much).

Are there any other drivers you think would be worth looking at? Or generally how to search for ones worth plugging into WinISD? I'm not finding many 8" full range options and only these SB ones have extensive specs.

As an aside is WinISD principally for low frequency calculations or is it useful to extend the plot out to 20 kHz?

 

[Sicaris]

Yes, it is a little borderline for as small an enclosure so might benefit from some added damping material. However, matters less if it does not fit well. There are other drivers and likely one that works better in sealed box. Unless you are willing to resize the cutout, it is the first hurdle for any replacement driver.

Do you have a budget target for this project?

Thanks for the insight. Resizing the cutout should be no problem. Budget wise the SB Acoustics prices seem fine but I feel like much more than that and I should be suggesting they buy a modern pair of bookshelves. The Wharfedale cabinets are quite nice but not much else to recommend them really!

If any other drivers spring to mind for a smaller cabinet please let me know. Or if there's a good site to scroll through and put parameters into WinISD.

 

[RickS]

Budget?

 

[Sicaris]

Budget?

Let's say £50 per driver, beyond that I think I'd recommend against trying to refurb them.

 

[DVDdoug]

It seems like these would have a bit too much upper bass and would drop off quite quickly in the low frequencies. The bump is only a couple of dB so probably barely noticeable, and probably desirable given the lack of lower bass.

To me, it looks reasonable for a small box.

I suspect there's not much to be done about the low frequency drop off

Not unless you change to a ported/vented design to see what WinISD shows you. ...And I don't know if that will help given the fixed box size and driver parameters. Typically, you can tune a ported box to go lower but the roll-off will be steeper in a ported design. Personally, I probably couldn't resist playing with the software to see what a port could do...

A different speaker might be different but the SB Acoustics speaker has a free-air resonance of about 40Hz so I think the cabinet size is the limiting factor.

...Small sealed active subwoofers often use built-in EQ/DSP and lots of amplifier power to overcome the "natural" low-frequency drop-off but I don't think you want to get that "involved" for this little-fun-simple project!

As an aside is WinISD principally for low frequency calculations or is it useful to extend the plot out to 20 kHz?

No, it's only good the bass range. I think it just "assumes" the response is flat to 20kHz because the Thiele-Small parameters don't cover that.

 

[moonlight rainbow dream]

Full-range driver will still need a crossover to sound good. It will, at the very least, need baffle step correction, but possibly also filters to control resonances. The good part is that something like a wiim streamer with its PEQs makes it really easy to do digitally.

 

[RickS]

According to online info, the Chevin XP has a mechanical crossover. Call it what you like, does beget a couple of other questions...

1. What is your expectation for sound quality for this project?
2. Did you consult Wharfedale support on potential replacement driver?

 

[Sicaris]

Interesting that crossover may be a problem, I may have misunderstood but it seems like the advantage of a full range using a whizzer rather than a coaxial is that the crossover is taken care of by the driver design. Is that incorrect?

Good to set some expectations. Sound quality is aiming for good enough for the price. Hopefully as good as they were originally (which I expect was mid-fi).

I haven't contacted Wharfedale, I just assumed being nearly 50 years old they wouldn't be able to help. There are salvaged drivers on eBay but given the way these degraded I'm not keen on that route.

Thanks for the PEQ suggestion @moonlight rainbow dream but this is trying to resurrect a fully analog system.

 

[DanielT]

Excellent, thank you. Is this the one you're talking about: https://sbacoustics.com/product/8in-sb20frpc30-8-paper/

I can see this has a reasonable frequency response according to their data. It seems to be more sensitive into the same load so should be louder for a given volume, is that correct? Are there any other factors to consider like the relatively small size of the cabinet with no port?

Thanks again!

Here, @ppataki uses that SB full-range driver in a 12 liter sealed box. With FR and distortion measurements:

SB Acoustics SB20FRPC30-8 based desktop project

Last year I did a project based on Markaudio CHR120 drivers in my home office Then this year when I did my rear speaker project using the SB20FRPC30-8 drivers I really got astonished by these drivers so I have decided to replace my CHR120 desktop system with the SBs I already have the SB...

www.audiosciencereview.com

 

[Sicaris]

Here, @ppataki uses the full-range driver in a 12 liter sealed box. With FR and distortion measurements:

SB Acoustics SB20FRPC30-8 based desktop project

Last year I did a project based on Markaudio CHR120 drivers in my home office Then this year when I did my rear speaker project using the SB20FRPC30-8 drivers I really got astonished by these drivers so I have decided to replace my CHR120 desktop system with the SBs I already have the SB...

www.audiosciencereview.com

Oh fantastic, thank you! I'll take a look.

 

[Sicaris]

Thanks to the advice in this thread and elsewhere on ASR I've now got 3 candidate drivers which I've plugged into WinISD. The SB Acoustics previously mentioned, MarkAudio CHR120, and SICA 8D 1,5 CS 8 Ohm.

The SICA looks pretty bad (unless a port is added, thanks for suggesting to model ports @DVDdoug it is tempting but probably too much for this project)

The MarkAudio looks best but I'm not sure enough to justify doubling the cost over the SB.

@ppataki your build log was very informative and I noticed you applied DSP and even mentioned you would prefer the MarkAudio over the SB in the absence of DSP. Is that due to the frequency response above 500 Hz which WinISD isn't modeling?

 

[RickS]

Thanks to the advice in this thread and elsewhere on ASR I've now got 3 candidate drivers which I've plugged into WinISD. The SB Acoustics previously mentioned, MarkAudio CHR120, and SICA 8D 1,5 CS 8 Ohm.

The SICA looks pretty bad (unless a port is added, thanks for suggesting to model ports @DVDdoug it is tempting but probably too much for this project)

The MarkAudio looks best but I'm not sure enough to justify doubling the cost over the SB.

@ppataki your build log was very informative and I noticed you applied DSP and even mentioned you would prefer the MarkAudio over the SB in the absence of DSP. Is that due to the frequency response above 500 Hz which WinISD isn't modeling?

Here is one that shows more promise for your application…

Goldwood GW-8003/8 8" Full Range Driver w/Whizzer

Goldwood GW-8003/8 8" Full Range Driver w/WhizzerPoly cone 8" driver with unique paper whizzer cone. The frequency range that this driver covers is extremely wide, making it useful as a ceiling speaker, background music speaker, or as a single-driver hi-fi speaker. The rubber surround provides...

www.parts-express.com

Is more of a closed box woofer than the SB and is fairly inexpensive (and on-sale currently).

 

[ppataki]

@ppataki your build log was very informative and I noticed you applied DSP and even mentioned you would prefer the MarkAudio over the SB in the absence of DSP. Is that due to the frequency response above 500 Hz which WinISD isn't modeling?

Both the CHR120 and the SB will need DSP if you want them to sound really great
For that matter, really any full range driver you go for will benefit hugely from digital correction

The SB will sound smoother and the MA will sound brighter (strictly subjectively speaking from my experience)

 

[Sicaris]

Excellent @RickS that looks like a good option. I'll have to see if there's a UK distributor.

@ppataki thanks for the advice, good to know DSP can make these shine. The SB being smoother will probably be fine for this application.