Vifa Projects
Copyright 2010-14 Troels Gravesen

Vifa PL14WJ-09-08 + R2604/832000
11 liter compact monitor
2008 project

The PL14WJ09-08 is to my ears one of the most smooth sounding 5" drivers ever made and no wonder it has been a steady driver in the Tymphany program for years and years. Due to cone geometry, coating and suspensions, it's got an even response all up to 7-8 kHz, allowing simple crossover construction. It's not particularly efficient, but the result is decent bass response down to 50 Hz in suggested cabinet. With a Qt = 0.36, it's a perfect driver for box simulation. Overall system sensitivity is around 84-85 dB/2.8 volts. The XT25TG tweeter is a well-proven tweeter too, so no further comments on this driver.


Vifa C20WH-07-08 + Monacor DT300/waveguide
2006 project

Looking at extinct Snell E/II and /III speakers, I came to think about the old Vifa C20, 8" driver. The C20 is found in numerous versions like the C17. The C20 has a lightweight paper cone, a narrow foam surround and the "H" provides a 90 mm magnet for a 1" voice coil, probably giving decent sensitivity. Googling the C20WH, I found a single shop where the C20WH was available, probably some old stock and this is what I found in seller's storage. This construction also part of HES-II, High Efficiency Speakers, part II


Vifa PL18WO-09-08 + Vifa XT25TG-30-04
2002 roject

Two well-know units, driven from a series crossover in a 24 litres floorstander.


The C17 story
2006 project

Part I: Vifa C17WH-69-08 + SEAS 27TFFC

Get 95 dB/2.8 volts sensitivity for your low-wattage amp - in case it runs 4 ohms speakers. The Vifa C17WH-69-08 is a "special" driver. Special because it's so ordinary - probably made in tenth of thousands - and special because a lot of things went right with this driver. Sometimes a driver turns out to have the right cone material and coating for a given size, thickness and weight; the right voice coil diameter; the right surround providing the right damping to cone motion; the right magnet size to provide useful TS-data, etc. When all the individual parts are made right, the result may be better than what we might expect from the sum of the parts. Read the first part of this long journey.

Part II: Vifa C17WH-69-08 + Monacor DT300 + waveguide

I've been looking at the Monacor DT300 tweeter for some time and finally decided to buy a pair. This is a 30 mm soft dome and how would this driver perform compared to my much loved ScanSpeak D3806/8200 tweeter? The latter has a 38 mm voice coil and really needs a supertweeter to make it up to 20 kHz.
The DT300 may be a suitable compromise for two-way systems providing a possible low point of crossover. What's even more interesting is a new waveguide made especially for the DT300 tweeter. This very short plastic horn increases sensitivity by some 6 dB at 2 kHz and a very simple 1st order crossover is possible with the Vifa C17 drivers. I never thought I'd make a 1st order crossover work properly, but this tweeter seems to make it possible, helped by the gentle roll-off from the C17 drivers.
Read second part of the C17 journey.

Part III: Vifa C17-III-revised - the C17 drivers

Aake in Sweden stayed home one day - alone - and played rather loud - and send me a note telling the tweeter appeared rather grainy and distorted at times and some mails back and forth made it clear there was something to it. I hadn't run the C17 particularly loud and doing so, I had to admit the tweeter took some serious cone excursion on certain recordings. Taking the speaker to the workshop and connecting a sine wave generator made it clear that something around 500 Hz wasn't as it should be. First I thought the front panel/waveguide really wasn't airtight and the C17 drivers would introduce some pressure into the unit, but disconnecting the C17 drivers made it clear this wasn't the case either. Read third part of C17 journey.

Part IV: Vifa C17 mk4, the final chapter
Time for the final C17 cabs and a few mods.

Qualifying for being part of my stock speakers, the C17s certainly needed some nicer cabs. Some 22 mm MDF sheets were bought and I took it to my local veneering company and had mahogany applied. Next to the veneering company is my local carpenter, having a table saw at the size of a tennis court, fitted with a huge saw-blade with uncountable teeth. Cuts MDF so sharply, I usually cut my fingers bringing it home in my car.
Read the final chapter of the C17 journey.