Get More Detail, Information, Richness, and Tonal Balance from Your Vinyl LPs: Versatile Graham Slee Accession MM Phono Preamplifier Corrects EQ in Separate Stages, Includes Volume Control
Taking a novel approach to addressing EQ issues and designed to eliminate input clipping on A2D (analog-to-digital) converters during vinyl archiving, the Graham Slee Accession MM phono preamplifier delivers seriously good analog sound and phenomenal versatility. Unlike nearly every other phono preamp on the market, Accession treats both EQ curves – first, the rising response of the actual cartridge playing the record, and then the level applied to the record – separately to produce more detail, information, and balance. Accession makes the music on your LPs sound as it was intended to sound. Its output-level control serves as a volume control in a dedicated vinyl-only system and doubles as the solution to eliminating clipping and getting the right levels into A2D converters. A fixed-level output, stereo/mono switch, and three EQ setting (RIAA, British, and American) options turn Accession into one of the most flexible phono preamplifiers in the high-end industry. Want to apply your own record EQ? A cartridge-only option changes the CV (constant velocity) output to CA (constant amplitude) and lets it happen. Accession even includes four capacitive load settings for further user experimentation. Built like a champions, this British-made beauty features a fully ground-planed board that's multi-point-grounded to the case (no star-earth systems), EMC- and ESD-protect inputs, gold-plated inputs and outputs, and Graham Slee's outboard PSU1 power supply. This is hi-fi done right. 100% Music Direct Guaranteed.
Accession Corrects Both EQ Curves In Separate Stages
All records require some compromises to cut and press the groove, which is why record EQ exists and why the phono preamp has the job of correcting it. But something else contributes to the EQ the phono preamp needs to correct: The actual cartridge being used to play records has a rising response – specifically, 6dB per octave, a 45 degree slope. It's completely different to the EQ applied to the record. Even so, phono preamp designers traditionally look at the combined EQs of record and cartridge as being one. Treating the two different EQs separately, Accession first strips away the cartridge's contribution to the frequency response. It then deals with the record EQ. The record's own EQ was applied when the record was recorded whereas the phono cartridge is applying its rising response in real time as the record is playing – two completely separate events in time. The combined "EQ's" make up a complex curve of different slopes. If you can EQ the contribution from the cartridge and amplify it, the curve will rotate 45 degrees. This is what Accession does: EQing cartridge first so all that is left to do is EQ the record's contribution, which Accession does in its second stage. Rotating the curve only takes a single opposing filter slope to do the job. It just so happens that a handful of solid-state amplifying devices have an open-loop frequency response that match the required slope, making the amount of negative feedback required constant at all frequencies on the slope.
Benefits Dedicated Vinyl Setups and Traditional Full-Range Systems
In a vinyl-only system, the volume control lets Accession drive a power amp and the fixed outputs can drive a headphone amplifier. In a traditional system, the variable outputs can be used into an ADC or soundcard to do vinyl rips while the fixed level output is connected to your preamp, integrated amp, or receiver for normal listening. The different record EQ possibilities make it great for archival duties if you have old mono LPs and EPs that don't sound quite right.
Solves Clipping Issues With A2D Digitizing and Archiving
The biggest problem encountered in digitizing vinyl is the wrong level of signal. Too much signal overloads the input of the A to D converter (ADC), resulting in a hard, clipped sound that ruins your efforts. Using an "L-pad" (an attenuated interconnect cable) can help, but with quieter records you'll be recording several bits down. A volume or output level control is the answer, but it's got to be followed by a buffer stage to get the impedance low enough to suit the ADC input or the results won't be right. Accession gives you both. The output level control is followed up by a high-quality discrete transistor buffer stage that gives you the low impedance drive your ADC expects. The fixed level output allows you to monitor what you're recording by connecting it to your main system, or to a headphone amplifier, as you record from the variable output.
Volume Control Ideal for Dedicated Vinyl-Only Systems and Traditional Setups
Not only is the volume control and buffer stage of use for digitizing vinyl, but it's the answer for those who only want to play vinyl and want the bare minimum of system components. Accession's output buffer stage is developed specifically to prevent input saturation from ruining the clean signal from the phono preamp section. It handles the full post-EQ peak to peak signal without any slew-rate limiting.
American, British, and RIAA EQ Curves Cover All Bases
Older mono records can sound a bit muffled or a bit too bright. It's because they were not recorded to "modern" RIAA characteristics like you get on stereo records. Up to the mid-1960s, "gramophone" record reproducers featured tone correction switches to equalize the different record tone characteristics. For vinyl, it boiled down to American and British versions competing with their different EQs. We saw it fit to include a switch to equalize them, as well as a mono switch for added authenticity.
CA/Flat and Mono Settings for Additional Versatility
We're often asked if we can make a "flat" phono preamp for digitizing acoustic records, but that implies a phono preamp without EQ at all. What you want is something that only reproduces the record's characteristics and that's exactly what Accession does if you switch it to its "Flat/CA" position (CA: constant amplitude). All records can be played this way, and during digitization, the EQ of your own software can be applied.