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So, why not explore that idea using the power of the Dark Side anyway?
This has been a private design study under consideration for over a year, but now some specific elements are coming together to support more concrete development to relatively challenging goals...
This has also been conceived in several possible configuration, now narrowed down to two main concepts. The common denominator is the mid woofer driver vendor, PuriFi, but beyond that there are several possibilities which have been under consideration depending on performance and cost targets.
Options which have been pondered....
NATW?
Low Frequency configuration
Substantial extension in frequency range and output level may usually be obtained through some type of reflex system. For lowest cost, this would normally be ported, but the characteristics of the PuriFi drivers are such that quite compact enclosures are feasible, which tend to render the use of a port sub optimum, unless a port loaded into a planar surfaces, as done in the Wharfdale REVA is employed.
It is well known that the design issues for passive radiators are more complex and the choices for an appropriate implementation may be relatively narrow... however, with a carefully formulated approach and the optimum component selection and tuning, favorable results may be achieved. The passive radiator also has the benefit of avoiding a midrange resonance from a long tube.
A proposed LF design synthesis will be presented which will be under construction in a cabinet whose basic concept is described. Two options are possible, one of slightly higher performance but nearly double the PR cost.
High Frequency driver configuration
For this project, it is obviously necessary that the final performance be well in excess of normal mundane standards- otherwise, why bother?
Only one dome tweeter has been given serious consideration, given its superlative track record for price/performance value and very uniform response and low distortion, but it is typically nearly impossible to source at this time. However, we have a limited stock on hand, and a test order has been placed with a distributor in a remote star sector which appears to be accepted and processed, so at least a certain number could be built using the Peerless DA25TX008.
However, as the rebel scum are sometimes fond of saying, "There is another...." solution.
Some initial results have been shared elsewhere regarding the TPL75 AMT tweeter, and will be posted here also; in addition, the results of a complete design proposal will be shared, though without vetting by measurements, the crossover details will not be revealed until fully proven.
Initial Details for value oriented design...
One of the PuriFi drivers on hand is the original PTT6.5W04-01A. These were sourced on a special order through Claus Neesgard before production release. This driver is more challenging to develop for due to the upper frequency cone behavior, and the midrange response usually noted in measurement on practical baffle sizes. However, with the correct intuition and principles, as well as a small Force Push from the Dark side, surprisingly acceptable results are possible, as shall be seen.
The raw response of the PTT6.5W04-01A on a 29 cm wide baffle:
This was a sealed enclosure, no LF output optimization. One viewpoint on the results is that the interaction of baffle step response and raw driver behavior creates an asymmetric hump in the midrange centered in the area between 600Hz and 800Hz; this requires a thoughtful crossover approach. Additionally, the upper range rise and cut off at 3500Hz creates another set of challenges.
One of the LF configurations in evaluation, used with a Dayton RSS210PR in a 16L net enclosure:
The TPL75 is an AMT HF driver from Beyma, intended for professional applications, and often isn't available from DIY component vendors.
This is their "smallest" AMT driver, but it is reasonably robust and shows low levels of distortion down to its corner frequency.
An initial crossover feasibility evaluation from the first test data shows promising potential for further development...
The approximate POC test cabinet front panel layout plan is straightforward, and could support either a back located passive radiator or a vertical port planar loaded at the bottom.
This has been a private design study under consideration for over a year, but now some specific elements are coming together to support more concrete development to relatively challenging goals...
This has also been conceived in several possible configuration, now narrowed down to two main concepts. The common denominator is the mid woofer driver vendor, PuriFi, but beyond that there are several possibilities which have been under consideration depending on performance and cost targets.
Options which have been pondered....
NATW?
Low Frequency configuration
Substantial extension in frequency range and output level may usually be obtained through some type of reflex system. For lowest cost, this would normally be ported, but the characteristics of the PuriFi drivers are such that quite compact enclosures are feasible, which tend to render the use of a port sub optimum, unless a port loaded into a planar surfaces, as done in the Wharfdale REVA is employed.
It is well known that the design issues for passive radiators are more complex and the choices for an appropriate implementation may be relatively narrow... however, with a carefully formulated approach and the optimum component selection and tuning, favorable results may be achieved. The passive radiator also has the benefit of avoiding a midrange resonance from a long tube.
A proposed LF design synthesis will be presented which will be under construction in a cabinet whose basic concept is described. Two options are possible, one of slightly higher performance but nearly double the PR cost.
High Frequency driver configuration
For this project, it is obviously necessary that the final performance be well in excess of normal mundane standards- otherwise, why bother?
Only one dome tweeter has been given serious consideration, given its superlative track record for price/performance value and very uniform response and low distortion, but it is typically nearly impossible to source at this time. However, we have a limited stock on hand, and a test order has been placed with a distributor in a remote star sector which appears to be accepted and processed, so at least a certain number could be built using the Peerless DA25TX008.
However, as the rebel scum are sometimes fond of saying, "There is another...." solution.
Some initial results have been shared elsewhere regarding the TPL75 AMT tweeter, and will be posted here also; in addition, the results of a complete design proposal will be shared, though without vetting by measurements, the crossover details will not be revealed until fully proven.
Initial Details for value oriented design...
One of the PuriFi drivers on hand is the original PTT6.5W04-01A. These were sourced on a special order through Claus Neesgard before production release. This driver is more challenging to develop for due to the upper frequency cone behavior, and the midrange response usually noted in measurement on practical baffle sizes. However, with the correct intuition and principles, as well as a small Force Push from the Dark side, surprisingly acceptable results are possible, as shall be seen.
The raw response of the PTT6.5W04-01A on a 29 cm wide baffle:
This was a sealed enclosure, no LF output optimization. One viewpoint on the results is that the interaction of baffle step response and raw driver behavior creates an asymmetric hump in the midrange centered in the area between 600Hz and 800Hz; this requires a thoughtful crossover approach. Additionally, the upper range rise and cut off at 3500Hz creates another set of challenges.
One of the LF configurations in evaluation, used with a Dayton RSS210PR in a 16L net enclosure:
The TPL75 is an AMT HF driver from Beyma, intended for professional applications, and often isn't available from DIY component vendors.
This is their "smallest" AMT driver, but it is reasonably robust and shows low levels of distortion down to its corner frequency.
An initial crossover feasibility evaluation from the first test data shows promising potential for further development...
The approximate POC test cabinet front panel layout plan is straightforward, and could support either a back located passive radiator or a vertical port planar loaded at the bottom.
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