All-tube preamp with DI, hand-built with custom components, just like the Manley Mono Mic Pre times two.
The Manley DMMP Dual Mono Microphone Preamp is an all-tube microphone primarily intended for use with modern capacitor (condenser) microphones. Now, 40 to 60dB gain, enough for most ribbon mics, is selectable in precise 5dB steps by varying the amount of overall negative feedback on the GAIN switch. This is a very interesting feature, allowing you to change the slew rate (speed), placement, and tonal balance of the sound from mellow and "tubey-er" through to faster, punchier, and more aggressive.
Tube complements include 1 x 12AX7EH hand-selected for lowest noise, and 1 x 6414 per channel for each high-current output stage. Each tube preamp in the Manley DMMP is painstakingly hand-wired using silver solder and audiophile-grade components. Double-shielded custom-built power transformers and custom-built high-capacity reservoir capacitors demonstrate Manley's modern power supply design approach.
When you need to get your tunes through some tubes before hitting a sterile digital recorder, the front-panel 1/4" Direct Input jack lets the Dual Mono Mic Pre serve double duty as a pure tube line stage for instruments such as bass, drum machines, and keyboards. Total gain in this mode becomes 20dB less than indicated on the Gain switch. Both transformer-coupled balanced, and direct (via humongous metalized film MultiCaps) capacitor-coupled unbalanced outputs are provided giving you the choice of audiophile/purist or big iron sounds. Perennial shoot-out winners, Manley single-ended preamp designs have become favorites among top engineers and home recordists looking for "that rich Manley sound with the tight bass and the top end that goes on forever" which begs to go direct to tape. It's a BIG sounding mic preamp.
What's so cool about variable Feedback?
The Manley tube microphone preamp's global negative feedback takes a small portion of the output signal and re-injects it back into the input stage, which greatly improves linearity and distortion performance of an amplifier. A tasteful amount of negative feedback is the key: too much and you're into poor transient response and phase shift problems. Manley generally uses somewhere between 4 to 14dB of feedback in their line preamplifiers. Within that window is a definite point of maximized stability with optimum sonic performance, giving you the choice of where you want to be. Changing the amount of feedback alters the overall gain of the amplifier as well as the slew rate (speed).
In the context of a hifi amplifier or preamplifier with the Variable Feedback feature, EveAnna (Manley) uses variable feedback to suit different CD's and recording styles when she's listening to music at home. "For the most part I keep the variable feedback controls around the middle but sometimes when I'm playing a CD which is kind of harsh and aggressive sounding or I just want to mellow out, I just turn those controls down and apply more feedback to get a smoother, richer texture. But when I'm the one in the aggressive mood, I crank 'em up for a faster, punchier sound. The bass gets tighter and the top end sizzles. Vocal placement; is more forward. And, oh yeah, it gets louder too!"
The "GAIN" switch on the pro studio Manley Mono Mic Pre, as well in the micpre section of the Manley VOXBOX is actually a variable feedback switch offering a range of 20dBs of global negative feedback in five settings of 5dB steps to alter how much variable feedback is applied around the tube circuit. This GAIN switch can be used in the higher 55 and 60dB settings (in conjunction with turning up the Input Attenuator) to achieve maximum amplification for quiet singers or lower output ribbon mics. With most "normal" condenser mics and applications, the GAIN switch setting can be chosen at will for sonic variety for a "more tube-y" sound in the lower 40 or 45dB settings, straightforward sounding middle positions, or more aggressive punchy sounds in the higher gain positions. There is no right or wrong with this switch. Have fun playing around with the Manley All Tube Mic Preamps—it will bring you some interesting results.