Despite the gloom surrounding its stock price of late, Apple delivered another blowout quarter on Tuesday, thanks in large part to iPhone sales. But if you took the iPhone out of the equation, the overall numbers were just OK as Macs had a so-so quarter and iPad sales fell on the low end of estimates.

Apple sold 11.8 million iPads during the quarter, which was lower than the 12.3 million to 13.5 million units that analysts had been expecting. During Apple's earnings call with analysts Tuesday afternoon, a few took the opportunity to grill Apple CFO Peter Oppenheimer and CEO Tim Cook on the matter. One question was whether the introduction of the $399 iPad 2 had hindered sales of the new iPad.

"We're just learning about elasticity of demand," Oppenheimer said. "The $399 iPad 2 is doing well, but the new iPad is on fire."

Cook said he was "thrilled with the results we've seen," since lowering the price of the iPad 2 to $399, though "it's too early to come to a clear conclusion." The cheaper iPad unlocked some education demand, Cook added.

Nevertheless, the numbers were a comedown from the 15.4 million sold in Apple's fiscal first quarter, which benefitted from the holiday season. Cook and Oppenheimer didn't offer any more reasons for the perceived shortfall. "The new iPad is on fire. We're selling them as fast as we can make them," Cook said. One possibility is that analysts based their estimates on the new iPad's opening weekend, in which it sold 3 million units.

To be sure, Apple is selling a lot of the devices. Since debuting the iPad in early 2010, Apple has sold 67 million of them. As Cook noted, it took Apple three years to sell that many iPhones and 24 years to sell as many Macs.

Speaking of Macs, those sales were also on the low end of estimates and grew just 7% over the year-ago quarter. Cook said one major reason was that Q2 2011 was a big quarter for Macs. Sales grew 28% in that quarter as the rest of the PC industry posted single-digit gains.

"Yes, I think there was some cannibalization from iPad and the market is slow," Cook said of Mac sales in the latest quarter. But the "primary factor," he said, was those year-ago sales.