CDP isolation options for improved HF?

Following recent thread on shelf material, I'd appreciate advice on supplentary isolation/vibration devices for my old CDP (Rotel 855). I'm mulling over new digital front end options, but meanwhile want to eliminate HF roughness now evident in my new ref system, without reducing PRAT or resolution. So how do I optimize the use of this CDP until the revolution? Some have suggested that air bladder suspensions compromise timing. Is this often true? Thanks. Ernie
Ernie you must experiment some, and add to your collection of isolation devices. If you are looking for detail cones are useful like Polycrystal or DH or Black Diamond racing, my experience with cones is you get an exciting sound but tends to emphasize upper midrange and treble, not my cup of tea. Bearing devices like Rollerblocks and Aurios MIB give detail without disturbing tonality, however they can be hard to use in practice especially if you have heavy AC cord to deal with. I use partially inflated 12" bicycle innertube under my CDP (cost $6)I find this gives me the best tonal balance, after trying the above items, commercial versions of this include Bright Star Air Mass and Townshend Sinks. Your Dac has great influence on HF quality, you may need to explore this area, also Auric Illuminator can remove some HF edge/glare,Sam
My experience with cones (tiptoes-aluminum) is exactly as Sam states above: midrange and treble emphasis giving an "exciting" but ultimately tiring and irritating sound. I'm using budget gear, like you, and find that I want to smooth things out, not zing them up. I would strongly recommend Vibrapods-very inexpensive and in my opinion great results-will improve just about every area of your sound, not just clean up the high end. You should hear more happening in the midrange and better bass definition as well. I have 12 in my system now and another 4 on the way for my integrated amp, whose stock feet are about to be removed! I'd suggest ordering 8 (at $6 each) for your CD player, 4 to go under an MDF shelf (the guy in the US selling on Audiogon and Audrioreview is also selling MDF shelfs for $6) and another 4 to sit under the player on top of the MDF shelf. Before you order, fill up a couple of zip lock bags with sand and put them on top of your CD player, getting the total weight so you know which pods to order. For about $60 including zip lock bags, sand, vibrapods and MDF shelf, I think you'll have an upgrade that will really surprise you-you'll be getting much more performance out of that CD player than you thought possible!
HDM, I also like vibrapods and use them where my partially filled innner tubes won't fit, like under DAC. If you want to use them under CDP without taking feet off I place them on 4x4 ceramic bath tiles, this height will clear most component feet and allow flexible positioning of vibrapods, as they should directly contact component body. The partially filled inner tube does the same things as vibrapod only slightly better. Some people also damp body vibrations by using "little rock" or DIY alternative. It also pays to use small level to make sure CDP is level after tweaks are applied, Sam
I 3rd the use of Vibrapods which I use on my CD player under an MDF platform, with great results. I also have two wheelbarrow intertubes (smaller than the bike tubes) that I use under our mini system (two box unit) in our bedroom. I don't know if they make these anymore, I found them at an old hardware store and they only had the two. I experienced the same problem with racing cones but was told that I may not have used the "right" ones on my CD player.
Hi Ernie, The problem with the use of pods and cone devices beneath CDP's and DAC's is that they are not "voiced" for specific applications whereas the component manufacturer will typically voice their products in "normal" domestic environments such as wooden furniture and "typical" isolation stands with wood or mdf shelving on both slab and suspended flooring.Because of this and the very wide variety of suspension techniques used in source components(ranging form neoprene transport spacers to spring suspensions to rubber chassis feet)the results of cones/pods are nearly always highly specific to the individual deck. A better approach is via high performance shelving and support materials and constructions with broadband vibration damping, dissipation or evacuation. This category of isolation measures almost always will have been carefully developed and voiced to take into account the same environmental and acoustic parameters as did the cdp/dac manufacturer-A much less hit and miss proposition having more predicatble and consistant results and ultimately more effective as well. Cones and pods may then be used in conjunction with the accessory performance shelving to fine tune the tonal balance and for further energy reductions and/or compensatory effects if so desired. Best, Ken Lyon (caterham1700) GreaterRanges/Neuance
Ernie, Sorry for the negativity of my last post;^) You might wish to try a few simple experiments of little to no cost to "adjust" your Rotel's presentation.It's been a long time since I've used an 855 so please bear with me as my memory is pretty vague about it's specifics(tho I recall it's sound very well).First, play around with the orientation of the mains power cord if it does not have a 3rd ground prong.If it uses rubber feet, try replacing them with a harder rubber dome or truncated pyramidal shaped footpad for starters.The harder(denser and less compliant) material may help evacuate vibration more quickly and still retain the primary voice and"suspension" of the Rotel. It will isolate better because of the smaller contact patch (bottlenecking floorbourne intrusion). Another, more drastic method if you use an stand/rack of the Target/SoundOrganisation/Standesign variety is to remove a large cutout in the mdf shelf, approx 5-6 " in diameter directly below the center of mass of your cdp(should be slightly offset from the center of the shelf to prevent standing waves, tho not absolutely critical as to the exact location,ie-1/2" from dead centre would be fine). The reason for this is to reduce the unsupported mass at the centre of the platform and thus reducing energy storage and time smearing of info via the trampoline effect.Any disturbance is then more quickly dissipated and less likely to intrude upon the music. Best, Ken Lyon (caterham 1700) GreaterRanges/Neuance BTW- you might also wish to investigate alternative interconnects like the inexpensive($150/mtre pair/RCA) but hugely pacey and involving Cabletalk monitor 2.1 or slightly warmish and refined Harmonic Tech truthlinks ($175/mtre pair/RCA).The HT's are commonly seen here at Audiogon. Audioprism quietlines are also an effective and relatively cheap means of gaining refinement esp in RFI contaminated environments.These are passive shunt filters designed to be placed in wall outlets with "noisey" appliances such as refridgerators and computers.The effects can range from pleasantly subtle to strikingly obvious depending on your particular AC line situation.
Subaruguru: I do not disagree with any of the suggestions in this tread, but you have to start somewhere. The manner in which I use the Vibrapods is as follows from top to bottom. The CD player with its stock feet resting on a 3/4" thick MDF platform which rests on four Vibrapods. Below the Vibrapods are the shelf in my cabinet. This way there is no need to remove the stock feet on the player and assuming that it was voiced with the stock feet you are not changing this aspect but only isolating the MDF shelf that the player rests on. I have not tried using more (than four) Vibrapods but will experiment with this when I order additional ones for my amplifiers and power supplies. This setup really helped define the bass and smooth the highs of my budget CAL player, without mucking up the overall balance. It was a big improvement. I also use the HT Truthlink IC's that Caterham mentions, but only occasionally when I have a listening session of poorly engineered (sound wise) CD's, other wise I use silver IC's. The Vibrapods were $24.00 shipped and the piece of MDF scrap was $1.00 at the local lumber yard.
You might try what I did: place a group of Vibrapods under a piece 1/4" tempered glass, which has also been damped by applying a sheet of DexDamp (a constrained layer damping sheet, similar to DynaMat). DexDamp can be purchased by the sheet (about 12" x 18") from marine supply houses, and sometimes from car audio installers. I got mine from a marine supply place in Seattle called HamiltonJet. They have a good Web site with all sorts of acoustic control materials:
Aurios? What are they? Sorry...only remember the homonyms--awfully good with milk! Seriously, where do I find out about them? Thanks.
Ernie, bearing devices like Aurios MIB and Rollerblocks are perhaps the best isolation tweak for improving resolution without altering tonalty. The downside is they are somewhat expensive and can be sometimes hard to setup especially if you have stiff AC cords. Good review for Aurios MIB at in the "archives" from a few months ago.
I agree with the suggestion of Aurios. I put them under my Electrocompaniet EMC-1, and they improved the detail, soudstaging, and imaging. I've seen then used for as little as $130. per set. I am also trying a Machina Dynamica Nimbus this week ( Supposed to be the best isolation table there is. Expensive, though.