Advice for novice speaker builder.

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Seems like an interesting (if tallish) speaker which appears not to be too demanding of woodworking skills. I suspect it would have a great mid-range performance?

The Vifa XT25TG30-04 appears to be available in the UK for about £30. However, I haven't been able to locate a UK source for the Dayton Reference RS225-4 or RS125-4 - any suggestions other than importing from the US?

Hi,

EuropeAudio, but note some have had bad experiences with
them. Confirm the drivers are in stock before ordering them.

Is inevitably tall, as are all MTM's with the tweeter placed
at the correct seated ear hieght, in that you have no choice.*
And yes its reason d'etre is non boxy midrange and vocals. **

x/o parts and tweeter from falcon acoustics.

rgds, sreten.

* if it doesn't suit your seating, of course you can change it.

** MTM's that measure relatively flat add a little emphasis
to the power response in the midrange, a subtle effect,
where the dispersion become more line source than
a simple MT, related to the MM spacing. They throw
a region of the sound more than an MT, in the above
design, all things considered its not a bad thing.
 
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The Vifa XT25TG30-04 appears to be available in the UK for about £30. However, I haven't been able to locate a UK source for the Dayton Reference RS225-4 or RS125-4 - any suggestions other than importing from the US?

I find amazing that a Briton doesn't realize that UK is part of EU, so buying from an EU country doesn't incur in importing fees, and shipping costs could be reasonable as well.
Audiokit in Italy carry Dayton drivers and I can suggest them as a satisfied customer. Alternatively there is Lautsprechershop in Germany, I haven't dealt with them but they have very good references. Stay away from Europe Audio if they don't have what you want in stock, because they don't answer to emails - never.

Ralf
 
EuropeAudio, but note some have had bad experiences with them. Confirm the drivers are in stock before ordering them.
<snip>
Many thanks for that. I had a look at EuropeAudio and the Dayton drivers are on a 3 to 4 week lead-time. Added to this, they offer the RS225-8 woofer rather than Paul Carmody's recommended RS225-4 - I'm not sure what the differences are or whether using the RS225-8 would involve crossover changes? I will download and compare the specs and also post a query on the US Parts Express forum.

On a different(ish) front, I now have 4 x Kef B139, 4 x Kef B110, 4 x Kef T27 and 2 x Coles 4001G, all of approximately the same age (long story about my accidentally acquiring a 2nd KefKit 3). Ignoring the fact that these are about forty years old, how practical would it be to build a speaker based on the Sunflower Open Baffle design but using 4 x B110 and 2 x T27 as MTM and 2 x B139 as woofers? Or even 4 x B139! Would it be possible to redesign the crossovers to accommodate these drivers?

Many thanks again Sreten for the lead - and likewise to Giralfino's warning and suggestions which I will certainly investigate

ps - Giralfino - I guess you haven't heard about our charming Nigel Farage :D

pps - Actually there is a bit more to it than that, communication with and delivery from a UK based company does tend to be a bit easier. For what it is worth, I have bought HiFi bits and pieces from Holland (DaDa), Denmark (Ortofon) and Germany ;)
 
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The conversion from WMT to WMMT is actually trivial, surv1v0r. :)

An externally hosted image should be here but it was not working when we last tested it.


You take an acceptable crossover, which is the KEF Concerto IIRC here, and wire the mids in series. You then adjust the values of the mid filter to double inductance and resistance, and halve capacitance.

It all works out. :cool:
 

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The RS225-8 is the 8 ohm counterpart of the RS225-4 (4 ohm). You have to redesign the crossover in order to adapt the different sensitivity. However, looking at the schematics, considering that the 2 midranges are 4 ohm each in series, I'd think that the woofer is the 8 ohm version.

As per your idea to use old drivers to mimic the sunflower, I wouldn't do that even with measurement gear and skill. Sell that old stuff to someone interested and enjoy modern and more capable drivers.

Ralf

PS Farage is not unknown here, but I've seen the same attitude many times here, and only from Britons, hence my comment. When UK will leave EU you'll happy to buy only from UK or pay duties importing stuff, in the meantime enjoy the free EU marketplace. ;)
I do, and delivery times and often shipping prices are comparable to domestic ones. I've found that communication problems are not related to language but to people. Again, this is not directed explicitly to you, as you bought abroad, but when I don't find something locally I think first on other EU countries, before the US.
 
The conversion from WMT to WMMT is actually trivial, surv1v0r. :)

You take an acceptable crossover, which is the KEF Concerto IIRC here, and wire the mids in series. You then adjust the values of the mid filter to double inductance and resistance, and halve capacitance.

It all works out. :cool:
Oh, I love that - what may seem trivial to you (redesigning a crossover) is right up there with brain surgery and rocket science to me I'm afraid - 'A Level' Physics was a long, long time ago; I'm still trying to learn to solder tidily without melting everything in sight!


The crossover diagram you have included is one of which I have a copy and I have previously asked if anyone can explain it in layman's terms.

I can understand that the signal to the B139 is rolled off above X Hz (low-pass filter) and that to the T27 is rolled off below Y Hz (high-pass filter). What puzzles me is what happens with the B110 - is the signal cut-off above and below (band-pass filter)? And what aspects of the crossover achieve this?

Incidentally, I'm not really asking for a free tutorial, I am trying to make sense of this via Google (LINK) ;)

ps - Thanks anyhow for the reply.
 
I can't explain the very standard mid crossover beyond saying the first two elements block the bass below 500Hz, and the second two rolloff the top end around 3.5kHz. Hopefully you can then align phase and level with the right design choices.

You can sim with similar sorts of drivers and get some idea what is going on: Downloads

But, you will need to make allowance for different drivers at the design stage. Hopefully KEF have got it near enough right. I am not sure tweeter phase is right though. I get something different. If it's a BW3, it might not matter really.
 

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Hi surv1v0r,

Where abouts in the UK are you?
- PM me if you like.

Yep, the midrange will have a bandpass filter. The 30uF cap and 4mH inductor form a second order highpass filter, which then feeds into the 1mH inductor and 7uF cap, which is a 2nd order low-pass. Between them, you get a 12dB/octave electrical rolloff at each end of the midrange's operating band.

Chris
 
I always feel an extreme sense of guilt when I am responsible for taking someone else's thread off-topic and yet I have digressed first into a discussion on where to buy parts (in the EU!) to build a Paul Carmody Sunflower and then into trying to gain an understanding of how crossovers work so I will stop now.

However, about a month ago I started a thread entitled "Crossover & Bi-Amping 101" and I would be keen to continue the passive crossover discussion there if anyone cares to pursue the question?
 
diyAudio Member
Joined 2007
F3 isn't important
Look at F10
I do not often totally agree with Sreten but he is absolutely on the money.
if you are not going to follow a proven design use cheap drivers for your first speakers. $200- total in drivers isn't an unreasonably amount because I guarantee you will stuff up "something" in the first DIY
My only advice is to use drivers that are easy to work with and I still use Vifa P-11s / P-13s and D-27s for that reason even tho there are much better drivers out there
 
diyAudio Member
Joined 2007
OK Jay I'll amend my statement
Use cheaper drivers for the first project, ones with smooth responses and no obvious large peaks and dips in the graphs.
Cheap doesn't mean a bad driver, sometimes. Some of the excellent Peerless drivers are very good value for money as well as being not expensive
 
Have you gone to a 10" woofer because you want to go sealed now?

And is the cab shape below still what you are planning with the new drivers? Dimensions are 7" top x 16" bottom x 43" tall. Driver centers are located 8", 32" and 38" from the bottom.
 

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Yea, that's a good choice although from the drivers artofwar has selected so far, I'm thinking he's after something of a little higher sound quality.

Troels has some nice larger size higher end candidates with Seas and ScanSpeak drivers at his site, here.

And the Finalists might suit as well.

But I don't subscribe to an outcome of certain failure that others have been suggesting if he wants to design his own as long as he gets the right kind of help and as long as he understands that after simulations and fine-tuning by ear, there is still a chance that something may be off and that measurements of the drivers in the cabinet may be necessary to get it right in the end.

But there are ways to increase the probability of success by using simulations alone. One is staying away from drivers that have a reputation for driver specs that may be less than accurate, like Aurum Cantus for example. Another is to choose drivers that have been measured under the same conditions by a 3rd party like Zaph for example. Another as I think you've mentioned, is selecting drivers with a smooth FR that will make xo work a little easier.

Helps as well if the speaker goals or criteria are well spelled out too. So things like budget, cab size, F3, sealed or vented or something else, minimum impedance, max SPL and sensitivity. We've got room size, placement (although I'm not sure if that's 1.5' from the front wall for the front or back of the speaker), higher sound quality and type of music so far.
 
You can spend infinitely more and it will not matter. A novice cannot be the decision maker if a sucessful outcome is desired. He absolutely must rely on the proper choices made by people who know the art of designing speakers.
sreten choice is quite valid and while you could go in another direction, the value of the sunflowers will be greater.
By this I mean the result will be VERY good and in the process will come to learn far more than anticipated (understatement of the year). Once the reality of todays ignorance hits you, maybe months later, sitting there happily enjoying what you've accomplished you'll understand and be glad for it.
 
A novice cannot be the decision maker if a sucessful outcome is desired. He absolutely must rely on the proper choices made by people who know the art of designing speakers.

Agreed, although I would allow that *some* decisions can be made by the novice.

But I think the OP realizes this as well. Thus this thread asking for said design advice to achieve his desired goals and expectations.

Maybe the difference in opinion is whether or not measurements are required to get it right. Or whether a novice, with guidance, can make a few simple xo adjustments by ear to voice the speakers. Certainly measurements are the best way to go but imo, simulations well done have a high probability of success with some fine tuning by ear. It's been done frequently enough, albeit less so on this site than on others. Granted it does take more time and effort on our part to do the sims and for some that's just not going to work out, but personally, I have extra time this winter and am willing to help as I am able.

But the approach does have some risk of failure and that risk might be considered to be greater with more money on the line. Then measurements really do become necessary and the novice has to ask himself if he may be up to that eventuality in the end. If not, a proven design may indeed be the way to go. Otoh, plugging a mic into your computer and running something like REW isn't exactly brain surgery either.

Concerning the Sunflowers: an excellent implementation and I have no doubt that they sound very good, but the Dayton RS line still strike me as below the level of SQ that the OP is looking for. And for his tastes in music, I think I would be shying away from metal coned midranges. Paper would be my 1st choice with a few exceptions here and there.
 
Founder of XSA-Labs
Joined 2012
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Artofwar,
If you are new at XO's and multi-way speaker building would you consider going the active DSP route? It is actually less expensive than good passive XO components for a three way, is extremely flexible so you can experiment with XO slopes, points, BW or LR, time alignment, etc. When I went from playing with single driver full range speakers to multiways I find that using a miniDSP and low cost class D amps very useful and you have a good chance at making them sound good.
For a 3-way you will need two miniDSP (2x4) units and qnty 4 stereo class D amps. This can all be done for $300 and you will have a 4-way capable system with 50 watts/ch (8 ch). You can still go passive by using the active DSP system to explore what XO points and slopes sound or measure best. But I think what you will find is that it sounds great and you will stick with it as it is cost effective and flexible and way to implement.
Good luck.
 
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