TW034XO + AP210ZO Suggestions?

[cyteen]

I have recently picked up a pair of each cheap from Maplin and am looking for a reasonably cost effective way of putting them together.

34 litres is probably the maximum volume I'd consider and I'd like opinions on how small the enclosure could get before it would not be worth building.

Other threads I have read seem not to have panned out with a crossover for either unit.

The crossover suggested for the KLS12 crossover seems it might be expensive and I'd like to minimise parts count.



AP210ZO response graph image1

TW034XO response graph image2


One last point is the amp I have requires an 8 ohm speaker (its a World Audio Design Kit34)

Many thanks.

[ThorstenL]

Konnichiwa,

Originally posted by cyteen
I have recently picked up a pair of each cheap from Maplin and am looking for a reasonably cost effective way of putting them together.

I would suggest to try a simple series crossover, similar to that posted by LC Audio:



This will need some tweaking, especially the tweeter level where I think you will be needing a much more substantial L-Pad. Try a 6R8 resistor in series with the Tweeter and a 22R Resistor in parallel t weeter and resistor to keep the impedance level on track.

With the virtue of the 34mm Drivers lower resonance and better power handling you can move the crossover down in frequency a little more, simply by multiplying all capacitor values and the inductor by 1.5.

If we look for standard values, an 0.68mH inductor is nearest preferred value. If we now apply the same factor to the capaictors we need 21.7uF (use 22uF) instead of 15uF and 9.83uF (use 10uF) instead of 6.8uF. This will pushnthe X-Over point dwn to around 1.8KHz.

I would suggest to consider firing the resultant speaker either directly forward (straight) or severely toed in, so that the listener is somewhat off axis, which helps smooth the sound arriving at the listener, on axis both drivers have notable problems in the response plots.

I do think you should also consider adding a supertweeter (one of the 10mm Audax Thingies with a simple small value capacitor in series). Try 1uF in series with the tweeter. Maplin used to have these, but I cannot find them now. You need a model around 87-89db/2.83V/1m, the 10mm or 14mm versions.

I hope this helps, as the X-Over is experimental first use cheap parts and build it up and measure, to see how things work out.

As for the Box, I stronly suggest you try the largest sealed box you can get away with. Fill losely with a suitable stuffing material. Consider using Chipboard with a thin Plywood overlay for the "wrap-around", Baffle plywood and rearwall Plywood or MDF.

Size the Box according to the classic golden ratio 1.618 (H) X 1 (W) X 0.618 (D) inside measured and place the drivers as assymetrically as feasible. With an 8" Driver I would go for at least a 12" wide baffle, but if you take my advise you make that more like 18". From that you get the other measures easily and quickly.

An enclosure in size and shape like the AN-E is not a bad idea, if much larger than what you had in mind. Leave the box sealed or use a port to tune the Speaker VERY LOW (around 25Hz port tuning or so), thge result may be unorthodox and flies in the face of conventional wisdom, but trust me it works quite well for AN, so why not for you?

Sayonara

[tiroth]

With an 8" Driver I would go for at least a 12" wide baffle, but if you take my advise you make that more like 18". From that you get the other measures easily and quickly.

Would you mind explaining why? Thanks!

[ThorstenL]

Konnichiwa,

Originally posted by tiroth
Would you mind explaining why? Thanks!

Only very briefly. Narrow baffles make the sound comparably thin EVEN IF you apply baffle loss correction due to poor wavelaunch and altering directivity throughout the format range. In addition, any diffraction problems by narrow baffles fall outside the HAAS window and are comparably much higher in level, meaning imaging is very much damaged and made un-natural.

A wide baffle moves the diffraction problems more to within the HAAS window (after mor ethan 1mS) and due to a larger distance to the edge the level of diffracted sound is lower. A wide baffle will support "wavelaunch" (remember, waves are spherical) to a much lower frequency and give better support to lower formants.

Acoustically speaking the modern narrow frotn tall tower speakers are about as bad as it gets, unless you build a linesource.

Sayonara

[tiroth]

Thanks, that's great info and gives me some search ideas.

[cyteen]

Thanks for the detailed response KYW. I'll follow your advice and start with the large enclosure first to see what these drivers can do unhindered. Living room space may demand something smaller long term tho.

As for the audax super tweeter, are we talking about the gold piezo which was recently discontinued. In which case can someone recommend a source or an alternative.

[D1GGY]

Cyteen,

i am so glad you created this thread, i have the drivers you mentioned, i purchased them from the Mapion super sale and have been woundering what to do with them.

Thanks for the advice by the other thread contributors, in particular i think i may have discovered why all my last speakers have sounde thin, i like the look of narrow slim speakers......... not good then Time for some fat boys 18" that will please the wife haa haa

M

[ThorstenL]

Konnichiwa,

Originally posted by cyteen
Thanks for the detailed response KYW. I'll follow your advice and start with the large enclosure first to see what these drivers can do unhindered. Living room space may demand something smaller long term tho.

Have a look at the AN-E. It's meant to be close to rear walls and sits on low stands. It can be surprisingly unobtrusive if care is taken....

Originally posted by cyteen
As for the audax super tweeter, are we talking about the gold piezo which was recently discontinued.

Hell no. That thing cost an arm, a leg and a kidney and was not THAT great (Heard in Heybroke Speakers) when used as conventional tweeter.

I'm talking about the TW10... or TW14..... Series.

Have a look. These are nasty cheap things, but reach quite high and they are only needed for the top bit of air. The predeccesor to the TW34 was in many BBC Monitors, without Super tweeter they always lacked "air", nothing to worrk a BBC Engineer mixing for FM radio, 15KHz upper bandwidth cutoff but noticable in "Real-Fi".

Sayonara

[cyteen]

I did find what look like cheap nasty things (TW 010 F1) for 7GBP at falcon acoustics, no luck finding a TW14.

Are these units (rated 25W) any better than the cts/motorola piezos (which promise 3k-30k) given that they will be brought in so high. These at least have a high power rating that more closely matches the the other drivers. A wide horn might help with the off axis although the sensitive might be a little high.

Just as an aside, would these narrow, non-wave launching speaker designs, benefit from glass wings in the same style as is seen with some of the open baffle designs. Would that be a way of keeping the look but providing the required baffle size?

[ThorstenL]

Konnichiwa,

Originally posted by cyteen
I did find what look like cheap nasty things (TW 010 F1) for 7GBP at falcon acoustics, no luck finding a TW14.

They may have discontinued the TW14 series too. There has been a death of drive units in the Audax Lines that recalls the Somme.

Originally posted by cyteen
Are these units (rated 25W) any better than the cts/motorola piezos (which promise 3k-30k) given that they will be brought in so high.

You can use both, but the Motorolas with sufficient voltage sensitivity tend to be hornloaded which moves their acoustic centre far behind the main tweeter (in terms of the wavelength we are dealing with). Using the smallest TW10 with enough sensitivity (87db) and if neccesarily cropping the TW34 faceplate is likely to give better results.

Originally posted by cyteen
Just as an aside, would these narrow, non-wave launching speaker designs, benefit from glass wings in the same style as is seen with some of the open baffle designs.

Yes.

Originally posted by cyteen
Would that be a way of keeping the look but providing the required baffle size?

You need to answer that question....

Sayonara