DTQWT-12

[lonewolfny42]

...says birth certificate...

 

[NorthBear]

Hello Richiddoo,

First of all, sorry I d'ont speak English.
I live in the south of France. (La Couronne, near to Marseille)
I am interested about DTQWT-12
I would like to know if you're finally satisfied by your speakers DTQWT-12.
Many DIYers seem to have problems focusing with the bass.
According to their characteristics, they seem to have a sound that is closer to sono than HIFI, no!?


I can tell you with humility: there is four factors to be taken into account to reduce frequencies that pollute the sound:
 - The shape
- The mass
- Rigidity
- The volume

How to put this under?
I had some ideas.
What do you think?

Sincerely,
NorthBear

[tmazz]

Welcome aboard NorthBear. 

[richidoo]

Hello NorthBear
You speak better English than I do French!  Thanks for posting about my speakers.

I am very happy with the DTQWT-12 so far. It may not show in these notes, because I am still focused on tuning them, and fixing problems that I overlooked before. I have not given my final review, which will be thorough, and positive, based on what has happened so far. 

I am listening to more music now with these speakers than I have in a long long time.  I think the acoustic damping of the internal horns is finished now, and I am happy with the compromise between less ringing and openness. I don't hear any objectionable ringing and I don't feel any stuffiness in the sound, this is with several different amps. It took about a dozen changes to arrive at this damping arrangement.

As for bass, I think you mean DIYers tend toward ringing horn than overstuffed. That is true, I think, because a ringing horn has drawbacks, but also allows the full extent of life and transient detail to come through. Overstuffing a horn to totally eliminate horn ringing also damps the back pressure on the cone and compresses it's transient response, so even the direct cone sound is lifeless and suffocated, just like in overdamped sealed speaker. But No damping makes the ringing overpower the direct sound, so some damping is required or it is even worse than too much.

I am interested in hearing about your 4 factors, please elaborate on each, if you care to.

For the DTQWT-12, the shape must be folded because to not fold the horns would make them 10 feet tall. I have 11 foot ceiling, so I was considering building them unfolded, but they sound good now so I will not bother. The shape of these horns is optimized using Martin King's Quarter Wave simulation software, which is the state of the art for horn design now. The horns could be improved by being unfolded and being conical rather than rectangular, but Troels designs for simplicity and economy to make it accessible for DIYers to build.

I don't believe that mass has any influence on the vibration of cainets other than to lower the resonant frequency, which makes damping more difficult. Carbon/foam carbon sandiwch is the ideal speaker building materials, very low mass, high stiffness, easy to damp.

Rigidity, yes, easy to damp. Same as stiffness. High mass materials like steel which are also stiff are good speaker materials, but are heavy, expensive and difficult to work compared to wood.

Volume is already optimized yb the Martin King software. I doubt it can be improved by listening and tweaking. The speakers designed with that software that I have heard have been excelent, this one no different.

I really hope that you will share your ideas and respond. Maybe you disagree with me, that is welcome and encouraged!
Thanks
Rich

[tmazz]

I am listening to more music now with these speakers than I have in a long long time. 

Rich I realize that the Nervosa in us wants to hear all the gory details about the performance, but that statement just about says it all.

I'm glad to hear you are enjoying them. You deserve to after all the hard work you put into this project. 

[richidoo]

Thanks Tom! I am enjoying them, I missed them when I was away for the weekend.

Just found out that this same Audax TW034 tweeter was used in my Legacy Focus 2020s as mid tweeter, with a Japanese Foster planar ribbon tweeter above it. I bought a pair of these tweeters and 4 ribbons  as spares from the organ factory after they and Legacy parted ways. I gave them to the buyer of my Legacys. There are not many traditional soft dome tweeters with honest 93dB sensitivity. It's a nice sounding tweeter, although not extremely extended, which is fine with me. The DTQWT puts it into a waveguide to add more sensitivity.

[NorthBear]

Hello Richidoo,

I"am very happy''to try'' to speak with you.
But at the same time, I am frustrated because I am convinced that I would have serious difficulties to explain technical thinks.
First of all, I guess you have the share of your remarks Troels GRAVENSEN. What did - it recommended?
 

Let me tell you about a few of my accomplishments.
I speak you about my speakers because my son is torn between doing the same speakers that I, and the DTQWT ...
In my case, for the last pair of speakers that I realized, I opted for a minimalist filter, a heavy material, one side of the soundproofing of two components and elitist.
 

I realized hyper rigid boxes with 30 mm HDF (High Density Fiberboard, ± 1 000 kg / m³) I know this is not the top, but it was necessary that I exhaust my stock.
To improve things, I pasted lead plates that I also had in stock.

I selected the speakers and filtering components of exceptional quality. (Duelund Cast - Mundorf L300 30/10e)
 All supplies are non-magnetic annexes: Stainless steel A4 - Brass - Aluminum - Teflon.
 The welds were made with the son's silver / gold.

Therefore, we neglect the''bottle''.
Only one scene of drunkenness LIVE shows that the cost of the cabinet is fully justified.
 What strikes''from the first notes, it is the ventilation and transparency.
It seems that the sound does not come from boxes!
We hear endless details and the music is expressed with a clarity, a sharpness, a rare texture and depth.
 The scale of the scene is impressive. The spatial position and the truth of stamps of each instrument are met. The attacks are dazzling.
 A fan of Jazz d'Antibes said: We taste here in the magic of Live!''
 


True, the sound is faster in dense matter
However, contrary to the notions of common sense, we found that some rocks do not resonate, yet good quality: the most obvious case is that of dolomitic marbles, which give only a dull sound at impact.
A friend has reproduced my speakers, but with this type of marble.
The result is net!
More transparency.

I have attached some links to this post.
Open them and uses an electronic translator.
I think it's worth just tired. Anyway, I am inspired.
http://www.deparisnet.be/Bruit/faqbruit/faq_bruit3_materiaux.pdf
http://aboudet.chez-alice.fr/doc_musique/son-nature.html # mozTocId214443
http://www.petoindominique.fr/php/amortis.php
http://www.spectra.fr/mousse-acoustique-a18.html
http://www.jeanmaurer.ch/Produits/Jm-technologie/techno-e-boitiers.htm
http://www.roches-ornementales.com/Site-Resonance-long/RESONANCE-LONG.HTML

So, tell me if you have managed to profit from it.

I enjoy to read you,
NorthBear

N.B. Is it possible to attach a photo?

[richidoo]

Merci Northbear

I am reading your post and enjoying the photos. I will reply soon.

In the Meantime, you may attach pictures using the link "Additional Options..."

[richidoo]

Good links, thanks!

I understand your message to say that your son is trying to decide to build DTQWT or a speaker that you have already built. It sounds to me like your own speaker design is very refined perfectionist and expensive.

The DTQWT is not a perfectionist speaker. It's compromises allow music lovers to find their satisfaction while using low wattage single ended triode amplifiers. Audiophiles seeking perfect transient response of a sealed cabinet and perfect coherence of phase linear crossovers will not find that here. But it is efficient, sensitive, musical, and cheap to build using the Jantzen kit. Minor cabinet resonance and some horn ringing is part of the lovely sound. Technical performance is more than adequate to enjoy all kinds of music at high and low volume. They sound like high end speakers, on the warm and forgiving side.  I would not call them audiophile speakers, but music lovers' speakers.

Troels Gravesen diy designs are intended for DIY constructors on a budget who want quality sound and high value. Of course his designs can be modified to perfectionist standards if the budget allows. I damped the interior surfaces with heavy roofing bitumen. That, along with the bracing described in the plans controls the cabinet resonances well. The internal pressureis minimal and the Mms is low, as is excusion at highest volumes. So there is very low source of vibration. Cabinet coloration is minimal with the recommended bracing and damping. Maybe I am wrong and less cabinet resonance would help, but it is already too heavy and I am bored of more mods.

First of all, I guess you have the share of your remarks Troels GRAVENSEN. What did - it recommended?

Sorry, I don't understand that. Try again?

[richidoo]

I was curious how the mid and tweeters would sound alone, since there is a TQWT version, with no woofers. I disconnected the jumpers and moved the bananas up to the MT posts. Nice, not bad at all. Only a little bit of horn color, very musical, but tillted up without the bass to balance.

Then I moved the SCs to the bass drivers only. Midrange melodies are audible, and the horn sounds slow, considering how much midrange is coming out. I know that bass is slow, but speeds up when mids and upper mids are added. Upper mids are pretty well attenuated from the woofers.

Then I reconnected the JPS jumpers. They don't fit well, because they are intended for 1/4" post, while these posts have a bigger post. So the jumper tongues are wrapped around the post at the narrower part where the bare wire hole goes through the post. The jumpers don't sit flat on the base of the post, but are tightened down pretty good against the nut. Still a lousy connection, since the majority of current must pass through gold plated brass nut threads to get into the post, which is then bolted to the tab washer inside.

Anyway, with newly tightened jumpers, the overall quality of sound improved noticeably. Even bass started to have that open, floating airiness. So these posts/jumpers are definitely a problem. I'll solder the crossover inputs together and use a set of different posts that I have on hand, still Dayton, but much better. I can't put $300 into super posts and spades.

I found this sales blurb interesting, especially about the clunky junk metal posts smearing the bass.
http://www.vhaudio.com/cablepod.html

[Face]

All you need: http://soniccraft.com/products/connections/bindingpost/cardas_ccgg.htm and http://soniccraft.com/products/connections/spade/vampire.htm or http://soniccraft.com/products/connections/banana/vampire_b12.htm

[richidoo]

Thanks Face, for nudging me...

I like the new avatar, I guess you finished them?

[Face]

Nope, moved onto something else, a 3 way bookshelf with a pair of Anarchy Woofers, Scanspeak mid and tweeter per cabinet.  I plan on finishing the BB speakers by the end of the year though. 

[richidoo]

 

[NorthBear]

Richidoo,

I send you onr image of my speakers

NorthBear