thoughts on the dbx Model 128

[kjohnsonhp]

My neighbor dropped off a nice dbx Model 128 for me to play with. I thought it might be fun for use with my TT and maybe when making CDs. I'll have to chat with Mallett about dbx since I think he has one.

Any thoughts on the benefits of the box? +/-

[Frzninvt]

The DBX 128 is a combo unit, it is essentially a 224 Noise Reduction Encode/Decode unit and a 1BX range expander housed in a single chassis. The older versions with the stereo triggering are not near as smooth as the final "Digital Series" versions that DBX consumer group produced before going under. If you do any kind of taping the DBX Type II noise reduction will amaze you with 90db S/N ration and Dynamic Range equivalent to a CD. The 1BX portion will make a difference but the single band models tend to add artifacts like "breathing" if run with higher threshold and expansion settings. The best models are the 3BX-DS 3-Band Dynamic Range Controller and the extremely rare 5BX-DS Computer Controlled 5-band Dynamic Range Controller. These units are the cream of the crop, the 5BX-DS has 5 indepedently adjustable bands of expansion, compression and impact restoration and can make a "DDD" full digital recording sound better. I use the best components that they designed and built in my system.

[Mallette]

The previous poster has a world of high end DBX experience I do not not disagree with his comments.

However, the "breathing" he mentions with the 128 can be minimized or eliminated with a deft touch and good ears. The results are significantl improvement in all but the best LP pressings.

I used the 128 and still use a 117 (same unit without DBX tape NX) in my LR system. I've a DBX 3BX in the main system now, which I think he'd agree is entry level to the "high end" DBX world.

Dave

[Frzninvt]

The DBX 117 is a nice component, one of the best DBX built actually that combined compression and expansion in the same unit. I have never heard one of the original 3BX units with the wood sides. I have been tempted to purchase one with the wired remote just to see the differences. On the breathing thing, I did mention only when run at higher expansion levels and threshold settings otherwise it's fine. It's nice to see people still using some of the fabulous gear that David Blackmer and the engineers at DBX designed and built. If you ever come across a 3BX-DS (Digital Series) at a good price pick one up you wont be sorry! The processing is much more refined. However, if your using it strictly for vinyl I would recommend the Series III unit instead since it packs more oooommmpppphh. If you ever need any DBX help please let me know. I am a fan as if you couldn't tell.

[jt1stcav]

Just curious, Frzninvt...I had a dbx Professional Model 234 stereo 2/3 way, mono 4-way crossover for my home-made 15" subwoofer a year or so ago...It worked great, but produced a faint hum through my Magnepans (moderate to loud music masked over the hum). When I traded the inefficient Maggies for my Cornwalls, the hum intensified 100%, making enjoyment of my stereo system nearly impossible, especially during soft passages! It was so bad that I sold it for an AudioControl Richter Scale Series III bass management/crossover unit (which produced no hum whatsoever). Is the external power supply (wall wart) for the dbx to blame for the hum? The AudioControl's power supply is internal, so I'm assuming the wall wart's the culprit. Does pro audio applications need not bother with hum and noise due to the loud music played at concerts and clubs, as opposed to home audio crossover units, where noise is critical to the enjoyment of the system?

[Frzninvt]

The current incarnation of DBX Pro products are designed and built by Harman International and I don't believe the quality is that of what people were used to with the DBX consumer group products with the exception of some of their high end components. I would almost say absolutely the outboard transformer was the culprit of your hum/noise problem. The DBX components I have all have internal transformers. The Audio Control Richter scale is a nice component with useful features (but it looks cheap), I tried the Audio Control Phase Coupled Activator (PCA) which is the home equivalent of the Automotive Epicenter. It can generate huge sums of bass but is more of a one note wonder. The DBX 120X-DS Subharmonic Synthesizer/Electronic Crossover is like having a Richter Scale and PCA in a single chassis and only one rack space high. The biggest advantage is the crossover in it is continuously variable (50-115Hz) and not fixed like the Audio Control. It also has fine tuning controls @ 28, 34, 40, & 50Hz which offers alot of flexibility. It can take a bass signal from 55-110Hz and synthesize it down to 28-55Hz restoring alot of lost low end response from bass shy recordings.

[jt1stcav]

That's what I thought...thanks for the response. At first I thought the cause of the hum was from the power cord near interconnects, but after much fiddling rearranging cables, that was not the case at all. I did miss the adjustability of the dbx over the fixed setting of the AudioControl, but now that I have but one source, and no need for a preamp or subwoofer, I've sold the dbx, and my brother's using the Richter Scale for his system (he also has the Epicenter in his car audio system, and with three 10" JL Audio subs and a 1000 watt Precision Power amp, the bass can get ridiculously low and loud)!