Rowuks Playback

What people are working on at the moment
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rowuk
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#1 Rowuks Playback

Post by rowuk »

Here is work in progress. What you don't see is the LF modules.

What you do see is my record deck made from a massive piece of marble. It is direct drive. The tone arm is a Cantus (opus 3) inspired linear tracker. I have several arm wands in brass, aluminium, carbon fibre and glass - this picture shows the carbon fiber arm with my Ortofon MC30 cartridge.


The speakers shown are a three way system currently with a 6dB/8va passive crossover (acoustically crossed over at 80 Hz, 1200Hz and 10K). They are time aligned. The woofer/midrange box is a transmission line, but the line is only used to linearize the impedance at resonance, the speaker is crossed over an octave higher than the line frequency and is well damped to prevent the back wave from getting in the way of the direct radiation. I have discovered that Thiele Small parameters give us a decent picture of what the speaker does at resonance, what certain alignments screw up a couple of octaves above the box tuning is never talked about.

The amplifier piggyback on the speaker is the RH307A Super designed by Alex Kitic with some changes in the Zener and CCS after talking with him. Two additional channels in the amp are not yet finished - one for the horn and one for the planar tweeter. The power supply for both channels is centrally located
Attachments
Marble base, polymere feet, heavier tonearm wands sound better
Marble base, polymere feet, heavier tonearm wands sound better
RH Amp on a bit of perfboard
RH Amp on a bit of perfboard
sand filled side walls, well damped transmission line
sand filled side walls, well damped transmission line
Last edited by rowuk on Sat Jun 28, 2014 11:04 am, edited 1 time in total.
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#2 Furniture

Post by rowuk »

Here is the equipment rack. It is firmly mounted to the concrete block wall and isolated from the hardwood floor. The power supply for the amplifiers is built into the triangular box on the bottom of the rack. The shelves are thick glass with copper mesh in them which is grounded.

The Macmini media centre is generally operated headless.
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Rowuk Playback.JPG
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#3

Post by Cressy Snr »

That is stunning :D
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#4 Basic thoughts on my playback

Post by rowuk »

I am in my late 50s and have been building "stuff" for many years. The beginnings of my DIY were like many others, just try stuff out and collect isolated bits of knowledge. Much of what I built in the early days was based on what "parts" fell into my lap.

About 10 years ago, I started to get "serious". No more just trying stuff out, rather listening, defining things about my playback that I thought should be better. Very soon I realized how much that I did not know - and that there is almost nowhere to go for help when SOUND is important. The forums talk about drivers, response, specs, topology, but other than the standard hi/audiophile terminology, there was no descriptions of what people were really experiencing. I pretty much write off comments about one piece of kit blowing something else out of the water as I have learned that the context has more to do with the chance of success than the actual kit itself.

Trying to build playback from sound backwards is thus a real crap shoot. So I started with the acoustical requirements of real music. This shows where we need the most output. I consider my playback still work in progress although there is very little to currently complain about.

My next project is the phono corrector, switchbox/volume control/buffer which will be based on Alex Kitic's RPa. My goals are 5 inputs with the hot and groundline switched out when not in use. The phono corrector will have multiple EQ curves as my record collection does have enough variety to make it worthwhile.

Musically my goals are actually quite simple: when the playback lets me just listen, "encourages" me to listen to complete albums instead of playlists, prevents me from using it for "background music" by drawing attention to the performance instead of the great highs/lows/transparency/dynamics, then I am happy. In many respects many of these goals can be met with an old valve radio with a single 8" speaker and I do enjoy listening to music this way too.

I can say what does not work: just replacing a cable, cartridge, an amp, DAC or preamp. Any of those things changes the complete presentation in a very big way and it takes time to get used to it - if at all. All of the future changes will be with small steps. The small steps are HUGE in the result.
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#5

Post by IslandPink »

Excellent - thanks for the pictures.
There are some very nice elements in that system . I agree with you on the philosophy too, and the difficulty of making progress in this confusing business .
The turntable looks superb . A well-done direct-drive is the way to go in my opinion. My solution was to use the Nottingham 'Hyperspace' but replace the weak motor and belt-drive with a Teres 'Verus' rim-drive motor pod. I have no plans to change !

For a phono amp, I will say there is a huge amount of music and tone available via a really good phono amp , more than you might imagine. I would definitely encourage you to think about an LCR-based RIAA , as there is a step-change in the bass/mid tone and the rythmic/tonal integration across this region if you do an LCR right . Nick has built something very 'cutting-edge' in this regard recently and could give some valuable advice . I have a phono 'upgrade kit' with 1.5k LCR chokes waiting to be built , once I can get past the speaker work !

Going back to the speakers - what is the bass driver you use there ?
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Paul Barker
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#6

Post by Paul Barker »

I am speechless.

What a shame you can't bring it over. But it is totally impractical. If I were a millionaire I would send a truck for you and put you up in 1st class acomodation. I'd also send for Alex.
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#7 Preamp thoughts

Post by rowuk »

Thanks for the comments.

The phonocorrector that I have in mind was designed by Alex Kitic many years ago. We have discussed some interesting mods to be able to switch EQ between RIAA, DECCA FFRR and some others. It could very well be that the interface is open enough to experiment with LCR. I am really more of a "listener than a tinkerer" and will read up on LCR and try and understand why people do what they do and then start asking questions here. People often get annoyed when we start asking for context and justification up front without knowing who we even are. I thought with this thread that my musings and practical experience concerning audio would be clearer to others, making the context of my questions perhaps more "tolerable". A smart ass yank living in sauerkraut land could be a bit much for audio-talk.

The upperbass/midrange drivers are Eminence Deltalite 2512 (not the 2512II version) reconed with a shorting ring on the voice coil to control impedance rise but that will change to a Fane Colossus 12MBN soon. I have them in another box for evaluation and am happy with what I hear. Because there are no real LF demands on the speakers (80Hz), the midrange qualities of the Colossus are just a bit more to my taste - the crossover can lose some additional correction too!
IslandPink wrote:Excellent - thanks for the pictures.
There are some very nice elements in that system . I agree with you on the philosophy too, and the difficulty of making progress in this confusing business .
The turntable looks superb . A well-done direct-drive is the way to go in my opinion. My solution was to use the Nottingham 'Hyperspace' but replace the weak motor and belt-drive with a Teres 'Verus' rim-drive motor pod. I have no plans to change !

For a phono amp, I will say there is a huge amount of music and tone available via a really good phono amp , more than you might imagine. I would definitely encourage you to think about an LCR-based RIAA , as there is a step-change in the bass/mid tone and the rythmic/tonal integration across this region if you do an LCR right . Nick has built something very 'cutting-edge' in this regard recently and could give some valuable advice . I have a phono 'upgrade kit' with 1.5k LCR chokes waiting to be built , once I can get past the speaker work !

Going back to the speakers - what is the bass driver you use there ?
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Paul Barker
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#8

Post by Paul Barker »

Regarding your turntable.

I'll live with my 301 and various heath robinson items. Sitting on the stone slab which broke my large metatarsel on the left foot that has me off sick right now.

Because Photobucket is forcing me into a time delay probably because I don't pay for it, a picture will be inserted here later as an edit.

If I were to make a DD turntable I couldn't think of anything more to add to what you have there and I shouldn't have thought to go half as extreme :shock: . At least you know you are done.
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#9

Post by rowuk »

If you were a millionaire then it would be better that Owston got some acoustic treatment to make it even worth bringing kit over.......

The curved sided speakers were actually quite simple. You take a circular saw and cut grooves into MDF. I used 13mm MDF and made the grooves 11mm deep.
After the inside is glued to the top and bottom pieces, the outside panels are screwed into place along the circumference (not in the middle yet) from the inside, then we seal the bottom up so that we can pour sand into the space between the panels from the top.
I had a woofer screwed to the bottom panel and fed it 10Hz to vibrate the box and get the sand to fill all of the voids. After about 20 Lbs of sand were gone, the first speaker was sealed up and then I drove a couple of screws through from the middle.

The finish is a stucco like cream with sand particles in it. It is used for indoor/outdoor waterproofing of walls. It is dense as hell and looks good. The surface is not perfectly smooth but very insensitive to showing dust.

The horns are plastic Faitals that I cut down and put an MDF ring around, sanded, damped with automotive undercoating on the outside and then painted red.


Everything that I do uses standard home tools that make an incredible mess with dust, glue and paint. The only real special tool that I use is a router to make bevels and curves even and consistent.
Paul Barker wrote:I am speechless.

What a shame you can't bring it over. But it is totally impractical. If I were a millionaire I would send a truck for you and put you up in 1st class acomodation. I'd also send for Alex.
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the slots are filled with sand
the slots are filled with sand
1.4" 600Hz Faital LTH142 horn
1.4" 600Hz Faital LTH142 horn
Last edited by rowuk on Sat Jun 28, 2014 2:11 pm, edited 2 times in total.
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#10

Post by Paul Barker »

Image
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#11

Post by rowuk »

cool!

There was a long thread at DIYAudio where these types of linear tracking arms were discussed at length. Everyone that I know that built one was happy and still uses it after years. I am not sure that many expensive commercial arms enjoy that success.....


By the way, I had a gravestonemaker make my plinth. Cost about €100 20 years ago.
Paul Barker wrote:Image
Last edited by rowuk on Sat Jun 28, 2014 2:05 pm, edited 1 time in total.
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#12

Post by Paul Barker »

Nice trick ref the horn.. Which Fane horn is it that you used?
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#13 oops

Post by rowuk »

Paul Barker wrote:Nice trick ref the horn.. Which Fane horn is it that you used?
Sorry, it was Faital LTH142

With the MDF ring they now are closer to the Le'Cleach than Tractrix. I picked a (longer) horn instead of a (shorter) waveguide on purpose. I believe that horns are primarily equalizers that limit losses if designed correctly.

I fixed the posts above
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#14

Post by Paul Barker »

Ref the linear tracking arm.

there is an issue with modern use of arms not all are aware of.

Many people covet the 12" arms, but the modern carts don't want a long arm, they do want linear tracking though. I am sstruggling to recall the actual issue, but it is to do with the cartridge compliance and the arm compliance.

Basically in short if you use an SPU cart for sure you need an SPU arm or a 3012. But if you use a modern cart you don't want a long arm. Sure you would like the better tracking of a long arm, but you don't want the frequency of it. so your linear tracking arm is better for you than your 12" arm.

What I don't know yet is how the SPU cart with onboard transformers sound like on this arm, because i just haven't got round to trying it.

I suspect the arm might bow in the middle. It is carbon fibre. Maybe it will be fine. Or maybe I should glue a length of basla to strengthen it along it's vertical plane.

Anyway we who prat about with air cushions have good tracking. One less thing to worry about.
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#15

Post by rowuk »

I think that the issue is less the length, rather that modern long tonearms are built for minimum mass and that makes the compliance of the cartridge critical with the arm resonance - especially if the phono corrector has no infrasonic filter.

After 5 years of mucking about with tonearm wands, I have found that carbon fiber is stiff, reasonably well damped but sounds like crap compared to a metal or hardwood arm when used with my Luxman, Ortofon or Shure cartridges. The "crap" I define as way less LF and much less "space" between instruments. Voices sound a bit "flat". I tried to improve the carbon fibre wands by adding mass (modelling clay) to different parts of the arm, drilling holes in the wand to change the tubes resonant frequency. I also changed the type of counterweights. I found no combination that worked even close to the brass tubed version. Aluminium worked fine when additional clay was added for mass. I am still not sure about glass tube. There is something really incredible about the sparkle, but I notice it so something is too much - it ain't resonance or mass though. It could be that the hardness (speed of sound transmission) acoustically "grounds" the cartridge better than other materials.


My favorite wand now is like this one - the original brass tubed one by the late Bo Hansson:
Paul Barker wrote:Ref the linear tracking arm.

there is an issue with modern use of arms not all are aware of.

Many people covet the 12" arms, but the modern carts don't want a long arm, they do want linear tracking though. I am sstruggling to recall the actual issue, but it is to do with the cartridge compliance and the arm compliance.

Basically in short if you use an SPU cart for sure you need an SPU arm or a 3012. But if you use a modern cart you don't want a long arm. Sure you would like the better tracking of a long arm, but you don't want the frequency of it. so your linear tracking arm is better for you than your 12" arm.

What I don't know yet is how the SPU cart with onboard transformers sound like on this arm, because i just haven't got round to trying it.

I suspect the arm might bow in the middle. It is carbon fibre. Maybe it will be fine. Or maybe I should glue a length of basla to strengthen it along it's vertical plane.

Anyway we who prat about with air cushions have good tracking. One less thing to worry about.
Attachments
Cantus.jpg
Last edited by rowuk on Sat Jun 28, 2014 2:45 pm, edited 1 time in total.
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