29 December 2010

Giveaway #5 - Fundamental Amplifier Techniques with Electron Tubes

The good folks at Elektor have provided us with a copy of Rudolf Moers' new book, Fundamental Amplifier Techniques with Electron Tubes for this giveaway.  Fundamental Amplifier Techniques with Electron Tubes is the English translation of Fundamentele versterkertechniek met elektronenbuizen (ISBN 978-90-5381-226-6) and has been available since last month.  The 834 page hard bound book covers the fundamentals of vacuum tubes and shows how to apply that information towards audio amplifier design.

We will be giving away one copy of the book.  The giveaway winner will be selected at random from the giveaway list on 10 January 2011.  You can get on the giveaway list twice.  Once by signing up for our RSS Feed through Email (you don't need to sign up again if you are already subscribed), and you can earn an second entry on the list by participating in the Giveaway #5 thread on the forum.  Note that the verification emails often ends up in the spam folder so be sure to check there after you have signed up to verify your subscription.  The randomly selected winner will be contacted through email for their shipping details.
Good luck!

07 December 2010

The Fine Wire Audio Cable Shoot-Out

After finishing the SuperCables CookBook by Allen Wright I decided to make some audio cables.  One of the concepts that Allen pushes in the book is very thin wires.  Originally I had no intentions of making any cables from the book but after reading through the book I got the urge.  According to Allen thin is in.  I chose to try a couple of the designs that use wire wrap wire (WWW).  Details of the cables that were built using WWW are noted in Part 2 of the SuperCables CookBook review.

The HiFi Test Set-up
The test set-up used to evaluate the cables consisted of an upgraded Oppo 980H, a diy build of the Nelson Pass B1 buffer preamp, a diy 6AS7 SET power amplifier and Fostex FE206En drivers in a back loaded horn enclosure.  I selected a number of test tracks which I thought had enough variation to exhibit any great cable sonics.  To make sure I was not biased I enlisted the aid of a golden eared friend, Ron from the Melbourne Audio Club.  He also brought along his test tracks.

Oppo 980H, Pass B1 Buffer, 6AS7 SET, FE206En Rear Horn

Cable Shoot-Out
We played through about half a dozen test tracks using both short and long runs of #1, Air-spaced Finewire RCA cables and set of #6, Air-spaced Finewire speaker cables which were 2 m in length.  My SET amp produces only 3W so fine wire speaker cables will work with this amp.  But will it be the best sound we can get?

What we found was in just three test tracks we could listen for:
  • The shimmer in cymbals
  • The breathiness in flute and its balance against a harp
  • The rich tone of a fully fleshed violin
Of course this in no way covers every tone or nuance of every sonic effect listenable on any recording but I feel it was enough to highlight the main differences in the cables.

After listening with the cable combination above we swapped the #1, Air-spaced Finewire RCA cables for a cheap $2 store bought RCA cable.  Some areas of the test music actually improved.  The sound stage appeared to widen or was it just smeared between the speakers.  The violin appeared to fatten-up or was the detail just lost.  Ron and I then, cable by cable, started putting back both sets of #1, Air-spaced Finewire RCA cables and the other various cables that we had on hand.

We started with the short #1, Air-spaced Finewire RCA cables which lead from the CD player to the preamplifier.  We also introduced my twisted version of the WWW interconnect cables and also my braided Silver Highway RCA cables.  I have built many sets of these high-purity silver wire RCA cables and everyone who has used them claims they are excellent.  At each stage we re-listened to the three test tracks.

What We Found
Without boring the pants off you with every detailed cable swap this is what we found.
  • The #1, Air-spaced Finewire interconnect cables work best between the CD player and the preamp (short cable, 150 mm long)
  • My diy Silver Highway RCA cables (900 mm) worked best between the preamplifier and power amplifier.  They worked better than my twisted WWW cable, but only slightly better.
  • Multi-stand heavy OFC speaker leads (3 m long) with heavy brass banana plugs only just outperformed the #6, Air-spaced Finewire speaker cables (2 m long).
Cable Measurements
Ron brought his dedicated capacitance and inductance meter and here are the cable measurements:

RCA Cables
#1, Air-spaced Finewire (short):  30 pF,  8 uH,  0.4 ohm
#1, Air-spaced Finewire (long):  30 pF,  13 uH,  1.5 ohm
Twisted cables (destination end):  13 pF,  8 uH,  0.4 ohm
Twisted cables (source end):  138 pF,  10 uH,  0.4 ohm
Silver Highways (900 mm):  71 pF,  2 uH,  0.3 ohm
$2 Generic RCA (1000 mm):  370 pF,  0.1 uH,  0.1 ohm

Speaker Cables
#6, Air-spaced Finewire (2 m):  25 pF,  17 uH,  1.5 ohm
Multi-stand heavy OFC (3 m):  210pF,  1uH,  0.1 ohm

Note: The twisted cables comprise of three wire wrap wires, only two of which are terminated at the destination end.  I believe the 30 pF of capacitance for some of #1, Air-spaced Finewire cables is due to the cheap RCA plug that was used.  The twisted cables had only 13 pF for the destination end which only has two wires connected.  Also the RCA  used on the twisted cable were heavy weight high-end types and I believe low capacitance types.

Just a Cable Suggestion
It is worth while trying different cables, weather you make your own or buy them off the shelf.  If possible, try borrowing some friend’s cables before outlaying hundreds of dollars on expensive ones.  Different combinations of cables can work better than just one cable type used throughout your system.  If nothing else, cable swapping and comparison will fill in an afternoon and you may enjoy the music along the way.

Mark Houston - retro-thermionic
To email Mark, type out the email address.

This concludes Mark’s three part series of the SuperCables CookBook.  For the full story, refer to the SuperCables CookBook (Part 1) which reviews the book and Part 2 of the SuperCables CookBook review which takes a look at a couple of the cable recipes.

Update (11 December 2010): I've updated the terminations for both the #1, Air-spaced Finewire RCA interconnect cables and the #6, Air-spaced Finewire Speaker Cables.  See the Skinny is in! - Thin wire audio cables thread for more information and further discussion.

DIY Cable Projects

05 December 2010

SuperCables CookBook - Review (2/2)

A couple of days ago I posted a partial review of the SuperCables CookBook by Allen Wright.  Of course there is not much use in working your way through a audio cable design book and then not building at least one of the cable designs.  In this second part of the SuperCables CookBook review I will share my experience with a couple of the book designs and also try a simple design of my own using some of the design concepts outlined in the book.

Over the past few years I have built a number of diy twisted RCA interconnect cables using high purity silver wire.  Some of the cable design concepts outlined in the SuperCables CookBook agree with my past construction methods.  So, can I use the new concepts to build a better interconnect cable?  There are several cable designs in the book and I chose to build the wire wrap wire (WWW) interconnect and the WWW speaker cables.  Wire wrap wire is typically 30AWG silver plated copper wire often insulated with Teflon.  It is cautioned in the book that the WWW speaker cables can be no longer than 2m and that they should be used for low power amps only.  My axe-of-choice when it comes to power amps is a 3W 6AS7 based SET (Single-Ended Triode) amp.  Perfect.  The book also cautioned that if you use these light weight speaker cables, you must remove all heavy connectors.

 #1 Air-spaced Finewire RCA Interconnect Cables

Constructing DIY Audio Cables
For my HiFi setup I needed to construct at least two sets of RCA interconnect cables and one set of speaker cables.  For RCA interconnect cables I built three sets in total of two different designs.  Following the book design for #1, Air-spaced Finewire, I built two sets of wire, one very short set and one about 900 mm in length.  The third RCA cable set was built by applying some of the concepts I picked up from the book.  For the speaker cables I followed recipe #6, Air-spaced Finewire.  All the audio cables were made using 30AWG wire warp wire.

For the Air-spaced Finewire speaker and RCA interconnect cables I followed the directions outlined in the book.  I even used $2 light weight plastic RCA plugs with insulated ears, as per the book.  But with the third pair of interconnects I mixed some of the concepts from the with other cable ideas I had used in the past.

In my Silver Highway RCA interconnect cables a three-wire braid using insulated pure silver 0.7mm (~ 22AWG) wires.  The extra earth wire is not terminated at the destination end.  The braided wires are encased in heat shrink and a ferrite choke is used at the destination end.  I used heavy RCA plugs and the connections are made using 5% silver solder.  The idea of the second earth wire is that it gathers electrical noise and drains it back to the source.  I think this cable sounds good and have built many sets for friends over the years.

To reduce the chance of picking up unwanted noise on these RCA cables which will be 900mm in length I lightly twisted the three wires using a variable speed drill.  The second earth wire was cut away at the destination end and fitted with a small choke.  High-end heavy Pro Co plated premium RCA plugs were fitted and silver solder used.  The #1, Air-space fine wire RCA cables may look cheap in comparison, but we are not here to win a beauty prize.

 My three wire twisted RCA cable

Where the book concepts have been applied in my three wire twisted RCA cables are:
  • Lightly twisted conductors;
  • Very thin conductors;
  • Silver solder;
  • Three wire construction;
  • Not terminating one earth;
  • Heat shrink to strengthen connection and hold twist in place;
  • No additional outer case;
  • Minimum length required;
  • Insulating wire strain ears.

Where the book concepts may not agree with my approach:
  • Heavy plated RCA plugs;
  • Ferrite choke;
  • Marking the cable directional;
  • Using this cable where the simpler two wire Air-space may work.

DIY Audio Cables made with Wire Wrap Wire

HiFi Listening Setup
I wanted to test out all these WWW cables I had made and followed the books suggestion to remove all heavy cables from my system.  The gear consisted of:
  • Custom Analogue modified Oppo 980H DVD/CD player;
  • DIY build of a Nelson Pass B1 Buffer (battery powered, WWW internal wiring);
  • 3W 6AS7 SET power amplifier;
  • Fostex FE206En back-loaded horn speakers;
  • Two pairs of #1 Air-space WWW interconnects;
  • 2M #6 WWW speaker leads.

HiFi Listening System

Air-spaced FineWire Cables Listening Notes
Usually when auditioning some new equipment you drop it into your existing system, pick your favorite test tracks and work your way through them.  You listen for bass extension and weight, mid-range clarity and texture, treble extension, soundstage depth and width etc. After a few tracks you will start to recognize that the new gear has made an improvement in some areas and a reduction in others. If you are riding a winner that day it will be win, win all the way.

But on occasions from the first few seconds of the first track you will be shaken to your very foundations.  You never expect it to happen but occasionally it does. You go from 0 to 100 in 10 seconds. The test set-up above caught my attention within the first few seconds of Stan Getz live. My mind struggled for the first second or two to track what I was hearing and place it in some logical place in conscience land.
The cymbals rang clean and clear like nothing I had ever heard.  All instruments were crisp, defined, real and raw.  It felt like I had thrown all my old gear out and just set-up all new gear from scratch.  Stunning.  And forget trying to find your speakers with your eyes closed.  They were gone, vanished never to come back.  What remained was a fat sound stage projecting from the back wall.  The sound stage could have been deeper but it was detailed and etched. 

I could go on for pages but let’s just say that these gossamer like ultra low-cost diy cables breathed new life into components, whose sound I knew very well.  They appeared to strip away so much vagueness in the presentation and laziness in the projecting of the over-all sound it was hard to comprehend. 
I spent six hours in a single listening session in front of the HiFi system above.  Not all recordings shook me as much as others but all seem to benefit.  Some recording far more than others and I’m not sure why.

Summary - Air-spaced FineWire Audio Cables
Ok, so you may have noticed there are no comments about how the air-spaced RCA cables tested or compared against my twisted set.  I’ll save those listening notes for a cable shoot-out and listening session report which will follow in a few days.  Just a comment about the #6 Air-spaced Finewire speaker cables.  Because I used no terminating connection they were clamped in the power amp and speaker binding posts.  As you can imagine, in time the thin wire will eventually break.  It is my intention to parallel a few inches of 1 mm thick pure silver wire to the ends of the speaker cables.  This should provide a light weight binding connection that will last for a while.

That’s it – now go and build some cables!

Mark Houston - retro-thermionic.
To email Mark, type out the email address.

For more details about the book, see Part 1, The SuperCables CookBook review.  In the third part of the SuperCables CookBook series Mark and Ron have a cable shoot-out with the new fine wire audio cables.  See The Fine Wire Audio Cable Shoot-Out story for the full details.

Update (11 December 2010): I've updated the terminations for both the #1, Air-spaced Finewire RCA interconnect cables and the #6, Air-spaced Finewire Speaker Cables.  See the Skinny is in! - Thin wire audio cables thread for more information and further discussion.

DIY Cable Projects