Robin Kent, the former CEO of struggling free music site SpiralFrog, has signed on to do consulting for Qtrax, a former competitor in the free-music category. Kent and SpiralFrog's Chief Marketing Officer Lance Ford, recently founded Rebel Digital, an advertising consulting firm. The duo will help Qtrax sell advertising in preparation for the September launch of the ad-supported music service. "We're going to help monetize themselves through advertising," Kent said of Qtrax. "Everybody has been talking about the advertising model, but there's actually very few people that know how to make that happen. We proved in our time at SpiralFrog, by what we were able to put in place in terms of potential deals, that we knew how to make this happen." Mainstream publications called SpiralFrog an Apple challenger months before it was due to launch last December. That same month Kent was ousted and soon after most of his executive team followed him out the door. Since then, the company has missed a second launch date and has recently begun testing the service in Canada, according to a note on its site.Representatives from SpiralFrog could not be reached on Sunday night. SpiralFrog had trouble cutting deals that would allow the company to offer music from the major record labels. To date, only EMI Music has signed on. By contrast, Qtrax has lined up EMI Music Group, Warner Music Group and is expected to announce Monday a deal with Sony BMG, according to CEO Allan Klepfisz."The CD is in a free fall," Klepfisz said. "Sales of digital tracks and subscriptions are a long way from making up the revenue lost from music piracy. We feel that the industry has to be looking at alternatives. If people aren't interested in paying for music, then logically the only possible candidate is the advertiser."