The Heart of Manley Labs

I’ve had a couple of conversations the past couple of years with mastering engineer Dave Collins about the D/A processor he was designing for Manley Labs, the company run by his wife EveAnna Manley. The 2014 CES saw the consumer debut of the Heart Monitor Controller 24/192 DSP ΔΣ [Delta-Sigma] DAC, which was being demmed in a system featuring Manley’s 25th Anniversary monoblocks, which use KT120 tubes. There are four digital inputs and Dave has kept the fully differential signal path as short as possible. Silicon includes a SHARC DSP and AD1955 DAC chips and harmonic distortion has been kept to a superbly low –120dB, and even that is the subjectively benign second. Price has yet to be decided.

What I found particularly interesting is that the Heart’s co-designer was Paul Frindle, a pro-audio engineer with whom I had become acquainted back in the days of Usenet. At very low signal levels, delta-sigma DACs suffer from what are called “limit cycle” spuriae—there is insufficient data in the delta-sigma loop and this leads to instability and the appearance of low-level enharmonic tones in the decoded analog signal. (You can see these in some of the spectra I publish in Stereophile’s DAC reviews.) Frindle’s patented topology adds low-level noise at the input of the loop to keep it busy and eliminate limit cycles. However, as the overall DAC circuit is differential but the noise is common-mode, it is canceled out in the reconstructed analog signal. Neat.

WJ ARMSTRONG's picture

I recall the original Manley Studio DAC from way back, and it was stunning; in fact I'm sure it would hold its own against just about any modern design.

I'm also glad to see the AD1955 chipset being used. I know that the actual DAC is supposed to make little difference, and it's the implementaion that counts most, but my own much loved Audio Analogue Maestro Settanta is equipped with this chip, as is the best digital front end I've ever heard period - Mark Levinson's No.512 SACD player.

So, expecting a cracker!