TPQWR - an easy to build mix of principles  
Wednesday, November 11, 2015, 21:16
Posted by Anders
Johannes Rodin came up with something very interesting...

The following images serves to describe the principal idea and is not to be regarded as any form of optimized DIY build plan, for example the oh so necessary bracing is left out.

Named TPQWR since it seems to describe the mix of principles involved in the best way, a Tapped Pipe coupled with a Quarter Wave Resonator.

The front resonator is the key according to Johannes, it boosts the tapped pipe's entire pass band efficiency and also adds a bit of extra efficiency in a region where it usually is beneficial to have it.

Simulations seems to indicate (speculative) that it will have very low "in pass band"-distortion due to extensive upper harmonics cancelations and that it will show less tonal deviations due to power compression compared to other design principles.

This mix of design principles is also very simple to build and it has about as good of a volumetric efficiency as it is possible to achieve being completely devoid of unused volumes when folded.

Principal model without necessary bracing:

Principal drawing without necessary bracing:

Faital Pro 10PR330 in 2PI:

B&C 10NW64 in 2PI:

Faital Pro 10HP1020 in 2PI:

Faital Pro 10HP1020 in 1PI:

Faital Pro 10HP1020 in 0,5PI:

More driver examples may be added in the future.
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Wednesday, March 25, 2015, 20:54
Posted by Anders
A new DIY project takes shape :)


Very advanced indeed...
(the source resistor is changed from 0,5 to 0,75 Ohms)

Closeup of the I/O stage

Overview of a more complete, but not finished, amplifier

Can it get simpler then this without involving depletion mode FET's and transformers?
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2" fullrange TB W2803SE on JBL 2386 upgrade 
Sunday, February 22, 2015, 18:00
Posted by Anders
I have updated my crazy top system, there is a new 2" full range driver, the Tangband W2-803SE, and some new higher grade components for the filter, 10uF capacitor over a 10 Ohm resistor, simple enough.

This is what it looks like:

The measurement setup, in the middle of the room, 1m above the floor and at 1m distance :

Raw measurement, no active processing:

1st parametric equalizer:

1:st parametric equalizer result:

2:nd parametric equalizer:

Active high pass filtering:

Final result (all of the above):

Impressive result considering the components are worlds apart and the really simple passive circuit, it actually sound rather good even before the active processing, but since i have the tools, why not use them right :)
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new place - new refinements of madness 
Monday, February 16, 2015, 19:31
Posted by Anders
My total disrespect for proven solutions and conventional thinking has reached new heights, seeing as my 2" full range drivers on JBL 2386 horns "solution" did not quite satisfy my need to provoke.

So what can you do with some way to small left over pieces of wood and a pair of decent size low frequency drivers? and how can it improve upon an already pretty far out top system?

Well... let's think outside the box, way outside the box, in fact, lets forget about boxes all together, this new set up is completely box-less and is built from just enough wood to complete a cup holder or two, that effectively eliminates the open baffle option that I know you where thinking of.

With some slight EQ the 24" drivers preform well down to and slightly below 30Hz, and can be crossed high enough to provide a seamless integration with the 2" fullrangers in the JBL horns at around 300Hz.

These drivers can almost to be regarded as a two-in-one solution, both driver and an open baffle design all in one, only in this case the baffle support is called cone :)
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DSTHAM - Dual Summation Tapped Horn - just a thought 
Thursday, January 8, 2015, 21:24
Posted by Anders
The idea I had was to sum two horn paths of different lengths over a single driver in order to expand the usable passband of the design in total.

The "Dual Summation" part of the principle stems from (SUM 1) the summation of the different horn segments, paths 1 & 2 and (2) the summation of the paths (SUM 1) over the rear of the driver giving rise to the second summation (SUM 2).

In order to obtain a more equal contribution of the two segments making up SUM1 they have been compensated in cross section areas according to their respective difference in lengths so that the shorter segment does not dominate (the law of least resistance).

In principle the SUM1 can be regarded as a first taper, and the SUM2 as a second taper, this also means a number of out of passband cancellations, balancing these summations with regards to both contribution (levels) and distance (timing) is perhaps not easily done.

I made a baseline balancing of these summations according to below, but I have no illusions that they will not need to be tweaked further, perhaps, or rather probably, significantly so.

Overview :

In principle :

Unfortunately this is a very difficult concept to mathematically describe and simulate with any grater accuracy using tools I presently have at my disposal, and as such it remains a paper product with no mathematical proofs of concept.

Somewhat more developed it might look a bit like this, again this is only in concept form, the brace at the driver provides both more path length(s) and will hopefully make the summation a bit more gradual.

Or perhaps even something like this :

We can and should also alter the path length ratio in order to try and find the point just before the path dependent cancellations becomes to severe, here is a non optimized example using the same size enclosure and principle folding, just showing it's possible to tune it :

An attmept to describe it (a start) :

The dual summation idea might even be applied in a Cyclops style folded TP (constant area) format :

This is simply an idea, no claims, no proof, and perhaps even a fair bit "out there", I just thought I'd share it with you for the fun of it in this our common interest :)
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