Have TW RAVEN AC1 SYMPOSIUM Ultra with Stealth top the best my far.Great bass,stage depth Highs,Wonderful midrange.
49 responses Add your response
TW suggests slate for a platform, which can be seen in photo's on TW's web site. I don't think granite is the best material to use, although slate may not be the best either. I am in the process of trying different platforms as well. I have constructed a platform of 3" thick Baltic birch plywood (4 layers of 3/4 inch). I cut a void in one of the middle sheets and filled it with #12 lead shot (smallest size) and will Formica the top, I might also Dynamat the bottom. I purchased 2 pieces of custom cut 2" thick slate which will go on top of this. Im going to listen to the table on the platform alone, then on the slate on top of the platform, then try a different platform made from some type of advanced resin. If I don't get too lazy, I am also going to experiment with points, Rollerblocks and Sorbothane in different places. Remember the ideal durometer and amount of Sorbothane depends on the weight it is supporting. You'll find pretty much all you need to know on Sorbothane's website. This is probably all overkill and there may be very little, if any, differences as the manufacturer indicates the table is not very sensitive to its support, as long as it's reasonable. I hope that gives you some ideas.
I used to have an unsuspended SME Model 10. I first tried Mapleshade brass cones on a 4" thick maple block. Not great. I preferred placing the turntable right on the top shelf of my Zoethecus rack. Then I bought a Townshend Seismic Sink for about $200 on Audiogon. Huge improvement. Better dynamics, more clarity, better detail, and deeper, more articulate bass. Then I bought a Vibraplane platform and it did eveything the Seismic Sink did, only more so. Finally, I installed a 136lb steel ballast plate to preload the Vibraplane and this improved the performance of my SME even more.
I'm a big believer in proper isolation now, especially for unsuspended turntables like the Raven. I strongly recommend a Vibraplane.
Thanks for the tips. The slate is a stop gap measure until I can find something better. It can't be worse (can it?) than the single sheet of MDF it's on now. I have it atop a Naim Fraim set, which are designed less for mass loading and more towards light weight isolation/dispersion. I have a feeling adding significantly to the shelves mass will defeat their purpose. I may be headed back to using a wall shelf. I have one now but it wasn't installed to handle a 50 lb. Raven. I will have to re-engineer its placement if I decide to use it again. I would contemplate a SRA, Symposium, etc, but I'd really like to be able to try one first so I can decide if I like it's effect. At least with the granite it only cost me $20.
I use factory bench with 4 inches slap of black granite right now with my TW. I have a friend that in the past had tried quite a few different types of stone for amp/speaker stands etc before and he found best result using black African granite (supposedly it has higher density than average granite!) In the past I tried slate but the result was not great. At least for those that I could find locally anyhow. I was trying to get a quarry to cut me pool table slate slap and it was a big hazzle and trying to get them to polish slate smoothly was almost impossible (may be I need a pool table factory for this). Anyhow, the one I got was not so great. However, I just located a used Symposium ultra locally that is big enough for my Raven AC-1 so hopefully I will try that in the next few days.
Vibraplane is also something I want to try or perhaps Minor-K. However, I am still thinking that eventually I might try to get BN 3 motors unit for my Raven so until I know for sure what size the turntable platform will need to be, I don't want to invest a lot on platform for my turntable just yet.
I use a wall shelf and have tried a number of isolation feet. The problem with heavy granite slabs is the wall shelf might be overloaded. You don't want the table falling off the wall.
I have used a number of feet, stillpoints, black ravioli, Herbies Isocups. the New stillpoint SS Ultra are marginally better than stillpoints+ risers, not enough to justify the added cost, but better
I have experimented with a variety of mounting possibilities for my TW AC 1, starting with a granite base(not good, a bit of ringing) to a HRS platform sitting atop an acrylic stand( not recommended). The AC1 has been tweaked with a BN PSU and motor. This required more real estate and led to a wall mounted 2.5" mdf shelf on brass cantilevers. Wall mounting is by far the best if it works for you. The AC rests on a HRS platform while the BN motor has a separate mdf platform and the whole package is on a wall mounted mdf shelf that can support upwards of a 100 kg !
Any of the well known iso platforms should work well. I would urge caution regd the feet. Any hint of rubber or non metal in contact with the feet can deaden the sound ,as I discovered. I have the HRS couplers that consist of a round metallic plate with rubber dampers on either side. Initially, I had the 3 TW footers resting on the metallic coupler sans the rubber damper on top.Sounded good but removing HRS couplers led to dramatic improvements.
Use only the TW arm board as opposed to a wooden armboard .
All the best
I am curious about wall mount shelf. My apartment has solid concrete floor with tension cable runnig through them. The floor is very solid with a layer of MDF and solid oak floor on top of concrete layer and is supposed to support about 400 kg per sq meter. The stereo equipment is placed near outwall of the apartment which is non weight bearing wall with windows and basically a brick wall. In this case, the floor is much more solid than the wall in my opinion. Foot fall is never a problem. In this case, would I still expect the wall shelf to be more benefitial? The factory bench/granite top that I used weight in at almost 100 kg.
My apartment has solid concrete floor with tensionThis is called a
'prestressed' concrete floor and is designed to allow greater spans between
supports, with thinner floor thicknesses.
It is achieved by reducing the amount of steel reinforcing in the slab and
substituting steel cables (within permanent sleeves) which then are post-
tensioned.......after the concrete has initially cured.
It essentially pre-cambers the concrete slab so that the 'dead load' brings it
back to horizontal.
These slabs are becoming more like 'membranes' and because of the spans
they allow.....can actually bounce?
With the right equipment one can hear the structure 'singing' or 'moaning'?
They are possibly the worst type of floors on which to mount audio
If the outer brick wall is non-load bearing.....it must be supported either on
the floor itself or a concrete beam structure spanning between supporting
If the latter.....it is less prone to movement than the prestressed floor and
fixing a wall-mount shelf to it (as close to a column as possible)....will be
Ebm, it's engineering and Halcro sounds like an architect. I understand about these prestressed concrete slabs. They are thin, and do flex, but they don't break under the design load. Think of a very hard, yet bouncy web. I imagine that they could even ring under certain loads.
Suteetat's apartment floor slab does not at all behave like a thick concrete slab on the ground. Whether or not a wall shelf would be better in his situation, I can not say.
Suteetat, I can't answer that. And I'm not sure you will ever get your floor to flex. I'm just saying that Halcro is describing a type of pre-stressed concrete slab and it will not behave like a standard concrete slab located on the ground. You may not have any issues at all.
However, if you can borrow a Vibraplane or other serious isolation platform for you unsuspended turntable, you should hear quite an improvement in information retrieval or resolution.
I agree that something like vibraplane is something that I would like to try. Unfortunately there is nothing locally similar available so I think I will have to wait until I know for sure what I will do with my tw regarding motor option before I will invest in vibraplane or minus k. In the meantime I probably will try symposium since I can use it with other equipments later and thy are not so expensive.
30cm is quite thick for a concrete slab.....especially a prestressed one. How do you know this fact?
The load carrying capacity of any floor has little to do with with it's BEHAVIOR under dead loads, live loads and impact loads. 400 Kg/m2 is not so great considering that 4 hefty men each weighing 100Kg can stand on a floor area not much more than this?
A trampoline can certainly support this load also but I would be loathe to locate my turntable on one?
I checked with my building engineer who has the building construction
blueprint and that's what he told me, regarding 30cm thickness. I don't
really know building specification and don't know what is considered norm
and standard of high rise elsewhere but overhere 400 kg/m2 is the
standard as far as I know.
Also my next door neighbor bought a unit below him and managed to find a
small space to drill a hole for a staircase between the 2 units who also
mentioned that 30cm thick concrete was what he needed to go through as
I used my Vibraplane on the unsuspended SME Model 10 and noticed a significant improvement. I now have it under my suspended SME Model 30/12. I would say the improvement is only very slight as the 30/12 already has a superior suspension and I don't think that the Vibraplane offers much additional isolation.
I have also heard the Vibraplane under unsuspended Brinkman turntables and the sound was extremely good, though I can not say what actually contributed to what in those unfamiliar systems. I did hear though that that Brinkman dealer sells a lot of Vibraplanes for his tables.
*Warning* a tad lengthy!
I had another lesson in Raven ownership the other day. I just could not get over how slow the perceived pace of LP's sounded. Everything sounded as if it were being played as a funeral march and I was hearing what sounded like "wow" (low note wavering) especially towards the last two tracks of an LP. Now my Michell Orbe never sounded slow and was a great pairing with my Naim amp/preamp. And I never detected any "wow" type fluctuations unless the LP had a off center spindle hole. The other very curious thing was that my room has a notorious upper frequency bump with notable reflection traits, and the Naim gear I have takes no prisoners on poor recordings ie., 60s-80's Rock. So, when these traits vanished I was shocked. Had the Orbe added that much extraneous noise to the playback? But it sounded so slow paced, no drive, no rhythm. None of this was mentioned on the Naim Forums, always good reviews. After days of head banging and freaking out, I was about to call High Water Sound when I remembered a review that mentioned something similar and it involved adding too much oil. I re-read the review and recalled how despite my best efforts to use very little oil, I sprayed too oil and did find a small puddle at the base of the bearing a few days later which I cleaned up. So, I removed the platter, cleaned both bearings/shafts and re-oiled very, very, lightly. NOW the rhythm and drive were much better, though not Orbe beating, HF extension returned since some of the HF nasties my room is noted for were back. Interestingly though it lost a bit of sound stage width/height and some detail. The perceived "wow" improved but did not disappear.
Raven traits: inner detail retrieval is greater vs. Orbe and VTA changes are MUCH more noticeable. In fact, I believe my VTA settings are quite different (higher) than on my Orbe. I'd have to pull the arm to get a comparison.
Comments appreciated, especially from Sonnyboy1956, former Orbe owner.
Gerardff, regarding Stillpoint setup : the answer is both.
You should be able to see 2 small gaps, one between Stillpoint body and T/T, and one between body and the bottom section.
I believe it is supposed to help decoupling.
An additional note is the gaps should be as small as possible without risking random contact (about 1/2 turn ??)
With a heavy turntable like this it's quite an awkward process to get the levelling and gaps correct without subjecting the tonearm bearings (or main bearing for that matter) to excessive shock. Might make sense to remove arm+board first, then re-check afterwards?
Hope this is helpful :)
I wonder if anyone knows the weight of Rave AC-1? I could not find it anywhere and can't find it on TW website either. One review mentioned that AC-3 is 70 kg. I email TW and asked about weight of AC-1 and total weight if I upgrade motor to BN motor. All I got for the reply was that with BN motor, it would be 6 kg more but no weight for Raven AC-1! I could try to weight it myself but afraid of getting a hernia doing so. So I wonder if anybody actually know the actual weight.
When I was contemplating the upgrade from the AC 1 to the BN PSU cum motor unit, I sent a barrage of questions to Herr Woschnik and he was always courteous and prompt ( same day response). If you need the weight to design a wall shell or any other mounting arrangement , I reckon you should be OK with 70kgs, ie 10kg for the BN motor, 50 kg for the TW AC plinth+platter with a safety margin.
All the best
Thanks for the information. It was really strange. Initially I sent eail Mr Woschnik and he answered within a couple of hours but without the actual AC-1 weight. I sent another email back to him and no answer now for 2 days. I think 50+ kg is more like it rather than 70 kg I saw in one review for AC-3. Now I found a local dealer for Minus K platform so I tried to figure outhte total load that I need. I understand that Minus K works best when you are closer to maximun load rather than being at the lower end of the range.
So I am looking at either 125BM-8 (40-59kg) or 150BM-8 (57-70kg). AC-1 definitely will fit 125BM-8 if the custom top (with larger surface area) does not add too much to the cost.
I use an HRS platform for my table- a big Kuzma that weighs about 160lbs. It will not isolate footfalls from a springy floor (which required more work including isolating the big antique table on which the whole affair sits). I would have preferred a wall shelf, but that wasn't feasible and would have required some real re-engineering, both of shelf and of system layout. The Stillpoints do a great job in decoupling vibration, but they are not really meant to address more dramatic movement like floor flex/footfalls, right?
(I have some ultra SS under one component and like what they do sonically).
Finite Elemente made a big shelf for wall mounting, but it ain't cheap. (The Living Voice folks seem to use those if you can find pictures of their factory listening room).
I owned a custom Minus K for close to four years. I sold it. I found the improvements too subtle to consitantly notice the differences. I sold it after I moved my system to a floor made of concrete compared to an upper floor I had my system in previously. SO unless you have serious floor issues I don't think it is worth it.
Another thing to take into consideration is how big a top you need for an AC-1 because with a Minus K needs to have the load in the center of the table for it to work properly. Having an outboard motor may not allow you enough room if the top is not much bigger than the table.
If you do go with a custom top don't get it from Minus K. It is just a sheet of Aluminum that they will over charge you for.
Thanks for the input. If I go Minus K route, the custom top plate would be quite a bit bigger than the footprint of AC-1 exactly for the center of gravity issue. It is a bit unclear to me at this time though if there is an easy way to see if the center of gravity is properly aligned. If it is a matter of distributing weight until say, leveling bubble level on the platform, I think it can be done easily enough using additional weight
Wall shelf is not an option with my current setup as the nearest wall is not weight bearing and the location would not be anywhere close to weight bearing column.
Pcosta, since you have Raven AC, I assume that you used Minus K with your Raven AC?
What do you mean by:
The 'centring' issue is not a problem if you use a top-plate supported on 4 equally placed 'spacers' over the Minus K stand.
I would assume the Minus K would not be working as good as it should, not to mention, putting the turntable out of level. In my experience with the Minus K having that top plate lean out of level would be compromising its abilities,
The amount of movemment can be adjusted on the Minus K but you are also adjusting the amount of isolation from its lowest speck on up.
Most turntables (and also audio equipment) are usually supported on either three or four legs so the weight is not evenly distributed over the top of the Minus K stand. It is distributed over three or four POINT loads.
Minus K simply advises that the overall load is placed generally around the centre of their top-plate. Even with my nude Victor DD turntable which weighs 10Kg surrounded by 3 armpods each weighing 12 Kg.......Minus K are happy that the arrangement is CENTRED on the top-plate. In other words.....the load does NOT have to be uniformly distributed.
However I would be happier to add my own top-plate ex butchers block or slate and support it on four neoprene or slate packers on top of the Minus K top-plate.
This would distribute all the loads evenly onto the four 'packers' which would be CENTRED over the Minus K top-plate.
Vibraplane was something that I looked at initially as well and it seems that ebay is the best source. The price is right but there is not a lot of information about it. Most sellers only shipped within the US and some will only sell it as is with no guarantee that it is actually functioning :(
I am also worried about servicing if the unit has a problem overhere! So Minus K seems like a safer choice for now.
I think that using separate platform on top of Minus K will also allow for easier centering of the mass rather than using a larger custom top. I am a bit worry about using aluminium as top plate as well. In the past, I experimented a bit with aircraft grade aluminium platform under speakers, turntable, amps etc. I find it to give better impact, more focus bass, extended top but at a cost of adding hardness and edge to midrange. Of what I could find locally here for TW, I find black granite (one of those with higher density than regular granite) to be better than local pooltable slate slab and both better than aluminium by a bit. I wonder what would be a good footer for the slab of slate/granite on Minus K since there is a little screws on top on K Minus so I can't lay a platform on top directly.