“Powering a Classic” – Demeter Amplification HBP1-800D Bass Pre/Power Amp

This Article Was Originally Published On: July 1st, 2014 #Issue 14.

“I also spent a lot of time reading books and just tinkering with things,” says James. Looking at circuitry, understanding it, repairing it, and designing it just seems to come to him naturally. “I seem to be able to see the design and just follow the electrons. I don’t really use schematics that much.” That is one of the electronics design world’s biggest understatements. In the early 1980’s, James designed the Tube Direct VTDB-2b DI box, to be used as an interface between an instrument and recording consoles. Over 5,000 have been made, and it’s still in production today.

James is extremely creative, and has designed and built his own tube-powered home stereo, as well as a 1,500-watt, tube-powered PA for his wedding. He has designed and built tube-powered optical compressors and spring reverb units. He has designed and built 3-channel tube guitar amps, tube bass amps and speaker cabinets for all those. He has designed and built many award-winning guitar pedals (the Tremuator, Compulator, Reverbulator, Overdriveulator, etc), direct boxes, mic preamps, and more. The Silent Speaker Chamber – a sealed cabinet with a 12” driver and built-in microphone – was designed so that guitar players could get “that tone,” which they can only get at high dB levels, without having to be crazy loud on stage or in the studio. I could go on. As I said, James is a creative and prolific designer. But what concerns us here at Bass Gear Magazine, right now, is the HBP1-800D Bass Pre/Power Amp.

James got started with bass preamps around 1981, when Leland Sklar brought in his Alembic F-1X preamp for repair. ”I opened it up and looked at it, and just thought I could do better.” The end result of that was the VTBP-201 all-tube preamp, which had a low- impedance output, allowing for longer cable runs, and the installation of a Jensen transformer for the direct output. It featured all-polypropelene caps, metal-film resistors, and power supply refinements. James says, “It was basically a Hiwatt-ish EQ, surrounded by the highest quality components available. I wanted to keep it clean, clear and quiet, so you could still hear your fingers and the strings, and still have some tube warmth to it. Sklar loved it and has used that unit for going on 30 years now – as have many of other top touring and session bass players.” Though it’s remained essentially unchanged since its creation, in 2000, the VTBP-201 got a minor facelift and a few other tweaks, resulting in the VTBP-201s.

In 1998, James created the HBP-1 bass preamp by adding the two-band, solid state, fully parametric EQ of his H-class pro audio devices to the VTBP-201, along with a fully adjustable active effects loop, tuner output, mic and line switching to the DI. The HBP-1- J adds a Jensen transformer.

For 2013, Demeter added an 800-watt class-D power amp (which he originally designed for use with the Jule Amps Monique preamp made by Jule Potter –reviewed in BGM #8) to his own two bass preamps, resulting in the VTBP-201-800D and HBP1-800D pre/power amp units. The class-D output section is rated at 800 watts into 4 ohms, and 520 watts at 8 ohms. The Jule/Demeter connection goes back to when Jule built Silent Speaker enclosures for James. Demeter also added this power section to the Demeter H- Bass 1600D – two 800-watt (at 4 ohm) power amps in a one-space rack unit; perfect for those who already have a VTBP-201s or HBP-1 and want a whole truckload of Demeter power for them!

A Closer Look at The HBP1-800D

Out of the box, the one-rack-space HBP1-800 D measures 17” wide by 10.5” deep by 1.75” tall, and weighs in at 11 pounds – pretty svelte for an 800-watt powerhouse! The front panel, from left to right, consists of both active and passive inputs. The active input uses a 6dB pad to prevent preamp clipping. Next is the Volume control, which controls the drive of the preamp, and the final output of the entire unit. “Drive” is a tricky work here though; don’t expect higher levels to result in preamp tube saturation, grit, grind or overdrive. About that, James says, “That’s not a goal for our preamps. But, if that’s something you want, we do make some great pedals for that.” Treble, Middle, Bass, and Presence are next on the front panel. The Treble, Bass, and Presence are shelving-type controls, whereas Middle is a peak-type (set at 1kHz). Treble shelving is set at 2kHz, Bass at 80Hz, and Presence at 3kHz, all with 6dB per octave curves.

The EQ in/out button engages the fully parametric EQ section, consisting of low frequency gain, with stacked Q and frequency select, and mid frequency gain and stacked Q and frequency select. The Q control lets you select how broad, or narrow, a range of frequencies surrounding your chosen EQ point are boosted or trimmed. Very handy for getting rid of specific problem points, or, boosting specific deficiencies that the 3-band EQ can’t address with that amount of focus.

Next is the effects loop in/out button (which enables the effects send and return jacks on the rear of the unit) and effects send and return knobs (which control the output level of the amp to your effects, and, the return level from your effects units back into the amp). The mute button mutes both the preamp and power amp outputs, and has an LED to tell you when it’s engaged. Finally, we come to the power off/on button, which also has an LED indicator.

The rear panel, from right to left, begins with the DI section. First up is the ground lift button, followed by a balanced XLR preamp output, a mic/line select button, a balanced 1/4” preamp output, an unbalanced 1/4” preamp output, the effects send and return 1/4” jacks, 1/4” tuner output, 1/4” unbalanced speaker output, unbalanced SpeakonTM speaker output, voltage selector for 120/220VAC (internal jumper must also be moved) and power cord connector.

The only downside, for some, may be the form factor. The one-rack space (1U) size means that when racked, it’s bigger than many other current class-D amps with similar feature sets. If that concerns you, don’t fret: Demeter showed a more conventionally packed pre/power unit (the VTBP-M-800D) at the Winter NAMM Show!

Powered Up!

Setting up, powering on, and sounding great may never have been easier. I unboxed the unit, slid it into a two-space rack, connected my Korg DTR tuner, the power cord, instrument cable and speaker cables, and set the HBP1-800D flat. James says “flat” on this unit is Treble at noon, Bass at noon, Middle all the way up, and Presence off. “Presence is mostly a leftover from when we initially built the 201 model preamps. Many speakers at the time didn’t have horns, and it allowed players to add a little more clarity. Many players don’t use it now, but we left it there for those who like it.”

For my initial “at home time” with the HBP1-800D, I used my trusty Sadowsky MV5JJ bass, and a Low Down Sound-built 15/6/1. The Sadowsky is strung with Sadowksy Blue Label stainless steel stings, and it’s a pretty aggressive bass, if you want it to be. The LDS 15/6/1 is an 8-ohm cab, and likes big power to open it up, so I was curious to see how the 800D portion of the Demeter would deliver.

With the Demeter set flat, and the controls on the Sadowsky set where I normally have them (Vintage Tone trimmed a bit, Treble boosted a bit), the Demeter delivered more or less what I wanted: crisp, clean, articulate, punchy, and plenty of power to open up the 15/6/1. I wanted a little more midrange, overall, and a little less “pillowy bass” from the big Eminence 3015LF. This was a snap to dial in with the fully parametric 2-band EQ. Set the bass frequency to 80Hz with a narrow Q and dial a little out; set the midrange to 800Hz and a slightly broader Q, and add a little in. Done. What a breeze! The Sadowsky was barking and grinding in no time, flat. You could hear the windings on the strings when you dig in, and nice, clean supportive finger style when just playing along, easy.

Next up for home testing was my ’57 Fender Precision reissue, strung with DA Chromes – about as different a thing from the Sadowsky as you can get. On this bass, I leave both the volume and tone all the way open. I disengaged the H-section para EQ and instantly had a really great Motown P-tone. To get it just where I wanted, I merely added a touch of Bass, trimmed a touch of Mids and Treble; easy, done.

On The Road with The Big D

The first few gigs I did with the setup above: Sadowsky, Fender, 15/6/1. That band plays a wide range of everything, from 1920’s to current (country, jazz, rock, and blues) and uses a Bose 2 Stick/2 Sub PA, which the bass doesn’t go into; so the Demeter and 15/6/1 had to fill the club. The Demeter had absolutely no problem, and my settings stayed just as they did in initial testing, with great results.

For a Monday night blues band gig, I used the Demeter with my Valenti 1955 Precision 5, strung with DA XL170 nickel rounds, and a Low Down Sound-built 12/6/1+ 12 sub. I ran everything set flat (with the passive tone trimmed down just a bit on the bass) and had nice, gnarly early P-tone driving the band just like that. Though after the first song, I made a quick adjustment with the parametric EQ to trim a little at the 80Hz point.

The next two weeks’ worth of gigs were with different bands. For the first weekend, I used my Alleva-Coppollo LG5, strung with DA XL170 nickel rounds, and a pair of Baer Amplification ML112’s. The Demeter/LG/Baer pairing delivered a nice, warm, punchy, articulate vintage J tone. Again, the Demeter did very well. I ran the EQ flat, though I did use a bit of the Presence control to get the edge I like out of the Baer cabs (which have no horns). I’m glad Mr. Demeter included that control. That’s all that was required to get the Alleva/Baer pairing speaking the way I wanted, with full, but controlled, lows, a nice midrange, and sweet highs.

For the next weekend’s gigs, I paired my Valenti J5 with a GK Neo112-II/Neo212-II stack. These two gigs were bigger clubs that supply FOH. The Valenti is loaded with Sadowsky single-coil J-style pickups and a Sadowsky preamp, strung with Sadowsky Blue Label stainless steels, and its aggressive voice mates well with the GK Neo cabs. For these gigs, I turned the Presence off, added just a touch of Bass boost, and trimmed the Treble and Mids just a bit from their flat positions. Boom! Instant bone-crushing modern-J tone.

For those last two weekends’ worth of jobs, I used the Demeter DI’s post-EQ setting at both venues. This is my preference, as long as I’m not doing anything drastic with the EQ on the amplifier to match it to cabs, or account for room variances. The guys at the mixing console both commented how nice the Demeter sounded through the board.

Last but not least, I took my 1961 King hybrid carved-top upright, L.R. Baggs Paracoustic D.I. and Low Down Sound 4×8+horn to a 5-piece jazz band rehearsal. Once again, the Demeter worked very well, and required no tweaking from flat. I typically trim deep bass a bit on the Baggs, and engage the phase-reverse function, if required to kill any feedback. That’s all I had to do to sound great for rehearsal.

The Final Word

The “on the road” portion of the review with the Demeter is fairly short. Why? Because the Demeter did great with all my basses, and, with all my cabs; and, the sound guys loved it. It’s super-easy to use, and it delivered repeatedly great results. In all cases, I had more power than I needed. In all cases, using the EQ to match various bits of gear was done quickly and easily. In all cases, I had no trouble making differently voiced instruments and speakers come out sounding the way I wanted. Almost invariably when testing amplifiers, I find one of my basses doesn’t work so well with it. Or, it may not pair that well with one set of cabs I want to use. Not so with the Demeter; all my gear paired up with it quite nicely. It really just doesn’t get much easier, or better, than this.

TONE-O-METER:
Huge power, easy to use basic EQ, plus fully parametric EQ and nice DI. Very pleasing and easy to shape tone. Everything you need for both studio and live work; and nothing you don’t.