2013 Holiday Projects - Ridding the system of resistor problems - diyAudio
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2013 Holiday Projects - Ridding the system of resistor problems

Posted 30th December 2013 at 04:35 AM by wlowes
Updated 22nd September 2014 at 02:10 AM by wlowes (add pic)

Two months ago I had great ambitions to complete a long in the planning short on execution music server by xmas. Seems I am too busy and just having too much fun listening to my system to make progress on big projects.

However, in a very low key way my system has made some stunning gains over the 2013 holiday.

My happy 6 year journey with a Lightspeed linestage finally ran afoul when an LDR packed it in. I retooled with some on hand bits while waiting for new LDRs to arrive. A snaffu with my order delayed that whole process. Meanwhile, my wonderful wife asked me what I wanted for xmas. I had been reading Arthur Salvatore's site and became interested in using an autoformer from Dave Slagle for my linestage. If your read the reviews and the technical specs, its intriguing. My system is perfect for passive. I only listen to a music server with triode ouput stage, short interconnects to OTL amps and overall have lots of gain.

On a whim I ordered the autoformers from www.intactaudio.com. I hooked them up project style before committing to a big work effort pretty enclosure.
Immediately they were interesting but not replacing the lightspeed. Thankfully the LDR shipment was delayed and I left the autoformers running 7x24. Over time they just kept opening up. After 100 hrs, the lightspeed was left in the dust. There is just a ton of micro information in the Slagle AVC that cannot be found in the lightspeed. If you study his site, you will find postings of square waves at 10khz that are perfect. Bandwidth is 5hz to 100-600hz depending on system. Sound.. wonderful if your system is compatible. For me, my system, another breakthru. YMMV

Next simple project up was to build DIY Manganin resistors for the I/V stage of my DAC.

I followed UDAILY suggestions for winding Manganin. Worked perfectly once I learned how to deal with wire I really can hardly see!
I built 2 x 60r resistors for I/V stage of my TDA1541a DAC. Original plan was for perfect non inductive winding using Aryton-Perry method. First real experience was I could barely see this wire even with a magnifying glass. I had to learn how to tease the varnish off with a hot soldering iron to tin the ends. I thought am I nuts?

I went with bifilar winding to make it simple for first shot. I used a short piece of round wood (end of a disposable chop stick) covered with 2 sided tape. I drilled a small hole through each end to attach firmly copper lead out wires. This step is important as the 46 gauge wire is so thin it is easy to break, so you want the leads to be completely firm so the Manganin sees no stress if the leads move. I had tried many different commercial resistors. My Manganin resistors replaced Caddock TF020.

Immediate success. The resistors dropped the sound floor resulting in much more micro info to appear. Yet another step forward in quest for natural relaxed but detailed sound. A lot of noise between instruments disappears. Bass is further extended. Sound stage on some recordings much wider.

Each resistor took about 6" of wire, so I have used 1 foot of my 100 foot roll. That means my resistors cost 17 cents each. Given Uriah's finding that they leave naked foil behind, and my experience that they dust best Caddock, Amtrans etc then I expect they are in the league of Rohpoint advocated by ThorstenL and Oliver Mei. Big difference in price however. I believe when I asked for a quote, they were in the range of $35 each. $70 vs $35 cents. You do the math. I am busy (re) listening to my entire collection.

I suspect that resistors of this quality have the biggest impact with tiny signals early in the chain. So my I/V is a big impact. I do not use a preamp or any other resistive device in the direct signal path. Passive linestage is now based on Dave Slagle's amazing autoformers. I am now intrigued to build resistors for the key locations of my amps.

I am writing after listening for about 2 hours. There is no other item that has not developed and opened up during the first 100 hrs so there may be more to come.

edit Jan 2 14 - As expected the resistors did settle in and further open up. Not a big change but just a little more relaxed and natural. Added a pic - Not much to them, just 6" of wire. I finished them by putting some silicone over the ends to protect the manganin and then wrapped with teflon tape.
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  1. Old Comment
    Hi wlowes,

    As you know, I am an inexperienced diyer.


    Please allow me to make a copy of a post I insert in another forum.


    I assembled a very nice LM3886 power amp with the help of someone.
    This amp has dual mono psu with some BL gates on it, and LDR resistors in the amp board. Everything is well wired with a nice copper foil from 47 Labs in the output for speakers. For signal I used silver wire, very thin. Nothing new but it works very well.

    I am using this amp with the Essence full range with Jordan drivers, from 47LAbs. They have 87db but they are an easy load to drive. The amp drives them with authority. Once I had an Anedio D2 dac (with vol control), directly connected to the amp. It worked just fine.

    NOW, I'm programming to buy a first generation Metrum Octave and have it upgraded from Paul Hines - essencially 8 better regulators and a totally new psu. This is an easy solution for me, very simple, no diy headache. I'll learn for more complicate projects but meanwhile I can have a decent system working. I want to connect it to the output stage from Lampizator, with the big tube, the best version if possible. If not, I begin with a modest version and upgrade on the board, later. Between dac and lampizator I am thinking about an autoformer from Intact Audio. I am seriously thinking about puting everything in the same box to avoid cables and plugs, but am not sure yet, this is a very radical decision - but reversible anyway.

    I have coper foil speaker cables and interconnects.

    The question is : what are the differences between the autoformer modules 350 us and the autoformer vol control? Does this allready assembled 350 us version have the right values to my project?


    Thank you!

    Amp
    Amp
    Amp
    Shelf
    Full range
    permalink
    Posted 18th June 2014 at 02:32 PM by polaron polaron is offline
 
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