Following the restoration of the Impulse H2s, I have been fairly inundated with requests to do the same for other Impulse speakers, with H2s joining a queue for the RFC coversion from far and wide. However, it's the Impulse Taus (later variants of the H2) which are next on the agenda.
I have received a lovely pair of Taus speakers but the mid drivers were shot (on testing) and surrounds gone. This is the second pair where I've found shot mid drivers and the very low dip in impedance in the original crossover may be a factor (who knows), but the RFC conversion offers several improvements one of which is a flat impedance load which doesn't dip much lower than 5 Ohms.
To this end, I have started with crossover box construction to take crossovers external, and have made headway with the crossover construction. Design has already been proved and completed on the H2s and as these will share the same driver compliment and crossover points, it's a safe enough bet to use the same crossover design although the Taus benefits from a slightly improved baffle design reducing diffraction spikes.
Crossover components awaiting assembly:
A little about the crossovers:
Being built up (not yet soldered) into the required circuit on boards which will be inserted into crossover boxes later on:
Boxes:
The customer wanted boxes in hardwood to closely match his speaker baffle timber (in this case Cherry).
The issue with Cherry I've found is that in planked form, it has a habit of twisting and doesn't seem particularly stable, so what I've done is to use (American) Maple and a reddish Cedar stain mixed with finishing oil to achieve the right blended colour tone. This closely matched the cabinets and the grain is not unlike the Cherry. The joints are blind dovetails, hand cut and assembled.
Lids will consist of smoke acrylic and the fittings and drillings for the boxes have yet to be done. The crossovers have been inserted just to try the boards for fit. They will sit a bit higher in reality as I will be introducing a damping layer between the box bases and the crossover boards, hence the generous free-board dimensions.
A little about the crossovers
These have been re-engineered from the standard versions to offer a number of improvements and to accommodate new mid and HF drivers.
Component quality is as good as it gets for passive crossovers without excessive spend, from the Pathaudio resistors to the Mundorf M-Cap Supremes and the Mundorf "Zero Ohm" bass inductors (actually 0.1 ohms).
They offer the following benefits:
I have received a lovely pair of Taus speakers but the mid drivers were shot (on testing) and surrounds gone. This is the second pair where I've found shot mid drivers and the very low dip in impedance in the original crossover may be a factor (who knows), but the RFC conversion offers several improvements one of which is a flat impedance load which doesn't dip much lower than 5 Ohms.
To this end, I have started with crossover box construction to take crossovers external, and have made headway with the crossover construction. Design has already been proved and completed on the H2s and as these will share the same driver compliment and crossover points, it's a safe enough bet to use the same crossover design although the Taus benefits from a slightly improved baffle design reducing diffraction spikes.
Crossover components awaiting assembly:
A little about the crossovers:
Being built up (not yet soldered) into the required circuit on boards which will be inserted into crossover boxes later on:
Boxes:
The customer wanted boxes in hardwood to closely match his speaker baffle timber (in this case Cherry).
The issue with Cherry I've found is that in planked form, it has a habit of twisting and doesn't seem particularly stable, so what I've done is to use (American) Maple and a reddish Cedar stain mixed with finishing oil to achieve the right blended colour tone. This closely matched the cabinets and the grain is not unlike the Cherry. The joints are blind dovetails, hand cut and assembled.
Lids will consist of smoke acrylic and the fittings and drillings for the boxes have yet to be done. The crossovers have been inserted just to try the boards for fit. They will sit a bit higher in reality as I will be introducing a damping layer between the box bases and the crossover boards, hence the generous free-board dimensions.
A little about the crossovers
These have been re-engineered from the standard versions to offer a number of improvements and to accommodate new mid and HF drivers.
Component quality is as good as it gets for passive crossovers without excessive spend, from the Pathaudio resistors to the Mundorf M-Cap Supremes and the Mundorf "Zero Ohm" bass inductors (actually 0.1 ohms).
They offer the following benefits:
- Increased bass sensitivity/efficiency through the use of ultra low impedance bass inductor
- Ultra low distortion performance from inductors and next to zero hysteresis
- High quality parts in the signal path and circuit paths kept as short as possible and hard wired
- Each component selected to within a few percent (max) tolerances and each speaker matched to under 1dB across the frequency spectrum
- Improved power factor and speaker efficiency
- reduced amp load (more amp friendly!)
