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Steve Marsh
Financial Interests: click here
Downstairs system - Digital Sources:  Vecteur D-2 CD Transport, Audio Note DAC Kit 1.2 with upgrades (ps chokes, tantalum resistors, Black Gate caps, copper grounding bars on digital chips wired to central ground, VTV silver foil/oil output coupling caps, Amperex pinched waist 6922 tubes)
Analog Sources:  Nottingham Analogue Mentor turntable with 10" Anna tonearm, Cardas Heart Reference, Goldbug Ms. Brier MC cartridges, (both rebuilt by Soundsmith), Simon Yorke S5 turntable with Pluto 5A tonearm, Cello MC cartridge
Preamps:  Hovland HP-100 MC tube preamplifier, Cello Audio Suite preamplifier with P-200 CD module and P-101 MC phono module
Power Amps:  Tron 211 SET amp with upgraded exotic-core interstage transformers (General Electric 211 power tubes, Western Electric 417A/5842 input tubes, RCA black plate 5U4GB rectifiers), Red Rose Model 2A Silver Signature tube amplifier (Mullard xf1 EL34 power tubes, RCA black plate 12AT7WA gain/inverter tubes and Tung Sol black plate 12AT7 driver tubes), Cello Performance amps
Speakers: WLM LaScala floorstanders
Interconnect cables:  Music Metre Fidelis digital, Harmony Audio, Acoustic Systems Liveline, Bastanis Epilog I, Cello Strings
Power Cords:  Bastanis Epilog II, PS Audio Mini Lab (preamp), Acoustic Systems Liveline
Speaker Cables: Bastanis Epilog II, Acoustic Systems Liveline
Equipment Rack: Adona AV45 CS6TW 6-shelf low profile rack
Power Line Conditioning:  PS Audio P300
Accessories: Marigo Audio Lab Orpheus Crossbow CD mat, one ceramic floor tile under each speaker to critically damp downward firing port
Room Size:  29’ long x 16’ wide x 10’ high (sunken living room with open floor plan, listening across width of room.

Upstairs system: Digital Source: Quad 99 CDP-2 CD Player
Analog Source:  Rek-O-Kut TR-12H turntable with Ortofon 309 tonearm, Ortofon Meister Silver cartridge, Ortofon T1 stepup transformer
Preamps:  Slagle Autoformer Volume Control, Klyne 7PX2.5 phono stage, Bottlehead Foreplay II line stage
Power Amps:  DIY HiFi Supply Lady Day 300B amps with maximum upgrade options
Speakers:  Bastanis Prometheus Mk. II speakers with Gemini tweeter upgrade
Power Cords:  Bastanis DIY
Interconnects:  Cardas Golden Cross, Bastanis Heartbeat
Speaker Cable: Bastanis Epilog II (bring up from downstairs)
Equipment Rack:  vintage modern teak stereo cabinet
Room dimensions:  22’ long X 17’ wide X 10’ high, with eaves
Review Component retail:  speaker level Ground Control, $149 per pair, line level RCA jack Ground Control, $99.95 each.

Financial Interests: click here
Analogue Sources: Nottingham Analogue Studio Space Deck driven by Walker Audio Precision Motor Controller. NAS Space Arm with The VTAF® from Pete Riggle Audio. Dynavector 17D2MKII, Dynavector 20xl, Denon 103, Audio Technica OC9 cartridges.
Digital Sources: Wavelength Audio Cosecant USB DAC v3 (Transcendental 16/44.1 DAC module) fed by MacBook with dual 500GB LaCie Firewire drives; Tube Research Labs fully modified Sony SCD-2000ES (for SACD playback). Secondary: TRL-modified Alesis ML-9600 high-resolution master disk recorder.
Preamps: deHavilland UltraVerve and professionally-modified/upgraded Eastern Electric Minimax (larger power supply, 12FQ7 ready, gain cut to 9dB) preamps; Allnic H-1200, self-modified Jolida JD-9A, Herron Audio VTPH-1MC and Monolithic Sound PS-1/HC-1 phono stages.
Amplifiers: Wright Sound Company WPA 3.5 monos, MiniWatt stereo amp, and AudioSector AMP-1 integrated amplifier. Secondary: Outlaw Audio RetroReceiver.
Speakers: DIY Altec 604 MLTL. Secondary: Zu Audio Druid Mk.4; Sound Dynamics RTS-3; REL Strata III.
Cables: Cardas, DIY WM-XTC, Audience, and Zu Audio Libtec cables; Cardas Golden Cross, Audience Au24, Audience Maestro [on loan] and TG Audio Lab custom copper interconnects. Secondary: Analysis Plus cables and interconnects.
Stands: Two three-tier Grand Prix Audio Monaco units on GPA Apex footers
Isolation: Main: GPA Monaco. Secondary: Lovan Affinity Pro6 Series rack, Acoustic Dreams Dead Ball Isolators; Neuance platform
Powerline conditioning: BPT 3.5 Signature; cryo'd Pass & Seymour wall outlets; Audience, T.G. Audio Lab SLVR, Analysis Plus Power Oval, and Zu Audio Birth and Bok power cords [both on loan]. Secondary: Brick Wall PW8R15AUD
Sundry accessories: HAL-O® Vacuum Tube Dampers, Herbie's Way Excellent Turntable Mat, VPI 16.5 record cleaner, Shun Mook Valve Resonators, Auric Illuminator, and Walker Audio Vivid CD & DVD Enhancer
Music makers: Epiphone Dot (Gibson ES-335 knock-off) and Chet Atkins CE (nylon-strung classical) electric guitars; Fender Blues Jr. amp; Privia PX-555 keyboard and 1906 Ellington upright piano.
Office system: Soundquest R601 Tube Hi-Fi FM/AM Classic Radio and a Gibson J-100 acoustic guitar
Room size & treatments: 26' x 19' x 9' (a fractured 'L', nominally 16' x 19' with 12' feet of the 19-foot dimension opening to the 20-foot section of the 20' x 12' kitchen/eat-in area); concrete slab, sheetrock walls. ASC Tube Traps and Sound Planks, Echo Busters absorbers, Shakti Hallograph Soundfield Optimizers and Acoustic Revive RR-77 Ultra Low-Frequency Pulse Generator.

When I first received Srajan's group email about reviewing a new Audio Prism product called Ground Control, I was immediately interested.  Byron Collett, one of the original partners of Audio Prism, described Ground Control as an accessory as innovative as some of Audio Prism’s past products like the CD Stoplight, QuietLine, ISO-Bearings and Noise Sniffer etc.

Since I am an owner and admirer of a Red Rose 2A Silver Signature tube amplifier, I knew that Audio Prism’s Debut tube amplifier was the predecessor to this amp and the inspiration behind Mark Levinson’s purchase of Audio Prism. While you might understandably question some of Mark’s past business practices, I don’t think many people would question his taste or knowledge of good sound. Hence I took Byron Collett at his word and signed up for the review.

When I first laid eyes on the Ground Control (GC) devices, I was skeptical but curious. What could be inside these little cloth-covered audio doodads? They were delivered in two varieties. One has a spade termination intended to be connected to the negative post of your speaker. The other has a socket that fits over and is inserted onto any RCA input of your preamp. I started out with the speaker terminal version.  

The first record on my Nottingham Mentor’s platter was Manuel de Falla’s Three Cornered Hat [London CS 6050]. The strings on this recording are a bit more strident than with most of the collectible London blue backs.

However with the GC devices in place, the strings became even harsher. I took the GC devices off and the string tone got better again. But I also noticed a general thinning of the sound. I repeated the experiment with Rimsky-Korsakoff’s Capricio Espagnol, Op. 34 [RCA LSC-2323].  This is a better recording but I still heard an increased edginess in the upper midrange. 

Not knowing if break-in was called for (Byron Collett emailed me later that "once connected the improvement is immediate but continues to break in over the next hour or so"), I decided to switch to CD as a source and let the system play with the GCs installed for a couple of days before critical listening.

This strategy paid off.  Coming back to vinyl a couple of days later, I played Barney Kessel's Some Like It Hot [OJC-168 (C-7565)]. I first played the cut "Sweet Sue" without the GC. When I inserted the GC, the entire frequency range became noticeably richer and more vivid.

  Stephæn's SideBar: From the maker of well-received products such as the Quietline Noise Reduction System (which I have used, to very good effect, in the past) to the Wave Guide common mode noise filter and more, Audio Prism now offers a new product called Ground Control. The devices provide "a self-contained local ground storage mechanism for all of the electrostatic moments that occur in music being reproduced via a given circuit or component. They help to maintain the coherence of electrons involved in signal transfer—i.e., making music—through CD players, preamplifiers, amplifiers and of all surprising things, speakers."

And MusicDirect,a retailer of the product, adds this: "In plain terms, the Ground Control creates a star-ground reference plane which stabilizes the electrical fields wherever it's placed, giving the connected component a greater grounding than the negative post of the loudspeaker, allowing the music to come together with astonishing time and phase accuracy."

If you’re so inclined, you can buy from MusicDirect with a 30-day money-back guarantee. That would have been a good thing for me. While I have used Audio Prism products to good effect in the past, not this one so much. So I’ll keep my sidebar report brief. I was sent two sets of Speaker/Amplifier (spade version) and one component (RCA) Ground Control via snail mail. The following correspondence arrived via email:

"Thanks for volunteering to evaluate the Audio Prism Ground Control. Directions: Ground Control comes in two versions, one with spades for speaker/amplifier. Merely attach to the negative terminal of each speaker before or after the attached speaker cable. Once connected the improvement is immediate but continues to break in over the next hour or so. Later (if so inclined) attach another set to the negative terminals on the amplifier. More than likely its improvement may be much more subdued. The second version has an RCA and is designed to attach to preamp or CD player etc. As an example, on a preamplifier if the negative is daisy chained together, only one is needed and may be attached to any input or output RCA. Experimentation may be necessary. The component version will have varying performance improvements due to internal component design and access to a quality ground point for connection. The best scenario is to solder one inside the component. That may be another version."

After 'breaking them in' for the equivalent of 40 hours or so, I experimented with the devices in three systems in three different venues; with three different speakers, two different preamps, two different amps, one integrated, one receiver and one CD player. Over a series of sighted A/B listening sessions, I sometimes reckoned that I heard a touch more body and low-level dynamics in the mids. But the differences weren’t tenacious enough to trust. In unsighted—not double-blind—A/Bs it became clear that I could not dependably identify when they were in or out. The same held true over periods of long-term listening. Since I was unable to reliably detect the possible differences in or out of the various contexts explored, I have to say that the Ground Control devices aren’t for me. Your mileage may vary.

Back to Steve Marsh: Additionally there was greater soundstage depth, bloom and bass was punchier. I then began to notice improvement in an area that I prize highly but find difficult to achieve and attribute - greater transparency in the bass.  This makes the entire performance more coherent. It has always been a pet peeve to have system transparency in the mids and highs, then descend into darkness and mud as you reach the lower octaves. So many systems are guilty.

Perhaps some careful readers noticed in my Tron Seven review that I added to my list of associated equipment. I recently purchased some 1988 Cello gear, namely the Audio Suite preamp, Performance amps and the Cello-rebadged Simon Yorke S5 turntable with Pluto 5A tonearm and Cello (OEM was Miyabi) moving-coil cartridge. There is some irony in that Cello designer Tom Colangelo,used to live two doors down from me. Before his untimely death in August 2007, I occasionally chatted him up as he walked his dog. When he learned of my tube equipment, he respectfully nodded his head. I in turn told him that I had heard the Cello system demoed at a New York stereo show in 1997 and found it to my liking. Deep down I suspect that we each thought to be better off than the other.

I finally set up the Cello equipment with its unique Fisher connectors and screw-down speaker cable connectors which limit use to spades only. The latter eliminated my Bastanis Epilog II speaker cables.  Not to be undone, I happily installed the Acoustic Systems Liveline speaker cables that conveniently switch between screw-on banana or spade terminations.

Right about this time Michael Spadafora and Hank Cohen visited. These gentlemen were referred to get my impressions of a new speaker they had developed and planned to launch. Before setting them up, we listened to my system for a base line. When I installed the GC, they could not hear the difference right away but also sat off axis. They moved in the sweet spot and this time I removed the GC while playing "Something’s Got to Give" from the exquisite Rosemary Clooney Sings the Lyrics of Johnny Mercer [Concord Jazz]. Immediately they noticed the loss of body in Rosemary’s voice. I pointed out that the bass had lost some impact and transparency too. We played the cut over again with and without GC and they agreed.

Because our ears are so sensitive to the qualities of the human voice, this may be the easiest area to hear what GC does. However, it doesn’t take long to realize that there is more body on all instruments as well. The trombone and tenor sax on the same cut were equally improved. Do not think that GC adds something not meant to be there. It sounds more natural and closer to the tonality and timbre of live instruments.

A week later, audiophile friend Bill Demars visited from Albany, New York for some listening. He brought along a pair of Welborne Laurel 300B SET amps to compare to my Lady Day 300B SET amps in the upstairs Bastanis Prometheus system. We warmed up the system and started off with the Lady Day amps. When we switched in the Laurels, we also swapped in my vintage WE 300B tubes from the Lady Day amps. Despite my protestations, Bill wanted to hear Jennifer Warnes singing "Bird on a Wire" from the timeworn Famous Blue Raincoat [Private Music PVT2092].  Her voice can sound edgy in some systems but here was buttery smooth. Next we installed the GC and immediately found her voice edgy. 

This second GC pair had zero time on it so we let it play. Meanwhile we rolled some tubes and substituted a pair of vintage WE 274B rectifiers for the Mullard GZ34. This increased bass and dynamics which seem to be weak in the stock Laurel. After more playing time, the vocals began to smooth out and the familiar GC benefits emerged. We both commented how the clarity of especially her voice was utterly fantastic! Removing and replacing the GC, we determined that the sonic benefits were mirroring the earlier ones in my downstairs system.

By now you must wonder how these things work. In a subsequent phone conversation with Byron Collett, he referred me to the description on the Audio Prism website. After reading it, I wasn't any more enlightened and decided to run things by an audio engineer friend. When I told him how it the device was used, he surmised that it was an RF filter of sorts.  However, Byron said it wasn't  After reading the full website description to my friend, he too was at a loss  He could not comprehend how it could possibly function as the claimed ground plane since it was so small. 

Byron countered that there is a lot of very fine wire (about 138 feet) looped inside the GC in a very special braid configuration.  He added that increasing the length of the GC by a ¼ inch would mess up the sound.  It’s critically tuned. [After concluding his tests, Stephæn remembered Corey Greenberg opening up a terminator cable box and likewise took a look inside one of his samples. This photo shows the innards - Ed.]  Toward the end of writing this review, I took a break waiting for the arrival of a filament supply resistor from Graham Tricker to repair my Tron 211 SET amp and listen to the GC with my tube equipment in the downstairs system.

Srajan informed me that Stephaen who was co-reviewing had opened up one GC. I had purposely avoided contact with Stephaen to remain unbiased. By now I had taken most of my listening notes and was confident in what I was hearing. Stephaen emailed me this photo of the innards. I opined that it looked like magnet wire. Stephaen agreed. Byron later confirmed that it indeed is a very fine magnet wire.

I placed another phone call to Byron and asked how the device worked. "We believe it provides a ground reference. We don’t really know how but we hear the improvement on a wide variety of speakers. Some of these effects can’t be measured. Or at least we don’t know what to measure." Interestingly, Byron feels that GC may actually be more audible on less expensive equipment with inferior grounding schemes. Bryon informed me that Bud Purvine, an engineer also known for his patented EnABL treatment of speaker cones, designed the GC. Bud Purvine is the mad hatter at O-Netics Ltd, where he designs very highly regarded audio transformers. Apparently they were used in Red Rose tube amplifiers. Bud now seems to have a new transformer design for upgrading the Red Rose amplifiers said to be a significant improvement similar in magnitude to what I heard from the GC. Bud used to work for McIntosh Laboratories but left when they switched to transistors. He then worked for Miles Nestorovic who had also worked for McIntosh. The mid-90s' Nestorovic NA-1 tube monos used Bud-designed iron. Back to my listening notes now.

In the midst of Sir Thomas Beecham conducting Schubert Symphonies Nos. 3, 5, & 6 [EMI CDM 7 69750 2], I decided to follow Byron’s suggestion and add the second pair of speaker level GC devices to the ground posts of the Cello Performance amplifiers. I was in the third movement and got some additional sonic improvement but not on the order of installing the first pair on the negative speaker terminals. Perhaps it was 40-50% of the first pair's effect. I felt it still was sufficient to spring for the second pair if funds allowed. Perhaps my favorite aspect of the GC devices is what they do for large-scale orchestral recordings. Here the improved bass impact and transparency allows more of the majesty of these performances to come forth.  With the GC in place, I find myself playing a lot more classical music.

I pulled out my classical warhorse French Opera Highlights [Mercury Living Presence 432 014-2, a CD I've had since it first came out in 1991 and played on every system I’ve owned as well as many others. Daniel Auber’s Overture to "The Crown Diamonds" is a sonic blast-out! I simply never before heard such explosive energy from it. Part of this was certainly due to the Cello electronics which take hold of the music with an iron fist. This CD allowed me to hear another effect of the GC. It seems to increase the intelligibility of the music, allowing all of the rich density of these phenomenal recordings to be heard in their full glory both on a purely information quantity basis as well as organizationally sorting it out across the soundstage. There was better focus to everything. I think this is at the root of the increased bass transparency since increased focus and space around the instruments in this frequency range translate to better transparency.

Many of the Mercury Living Presence recordings are known for their hall acoustics. I never heard them rendered this realistically. In the whirling dervish ending of Georges Bizet’s Danse Boheme from Carmen, there are several timely tympani strikes that came through so clearly yet in just the proper proportion. It was one of those moments where you realize the brilliance of a small compositional flourish. The transparency increase from the GC allowed me to hear this more clearly.  To check, I removed the pair of GC on the amplifier’s negative terminal. I definitely wanted to put them right again.  The magic was still there but not to the same degree.