Disclaimer that this entry is just a scrap book of my personal journey with a build. No fresh engineering here, so those seeking engineering insights can save the read.

That said, my new music server is now fully burned in, and for me its a delight. It is a collage of ideas developed by diyaudio members and by Lukas Fikus, aka Lampizator. Thanks to all who contributed. I hope these notes pass on some ideas for others.

Basic Approach
My approach is heavily influenced by Lukas of Lampizator fame. I have enjoyed his tube output amp design in my previous DAC, and several cd players. He got me interested in the TDA1541a, and I have had many years of happlily tweaking it for best sound. This server has a clone of his level 6 DAC with tube rectifiers, dual mono supply and film caps in CLCLC configuration.

Also, my digital evolution came via CICS CMP which taught me to appreciate a minimalist PC processor with network attached storage...

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...

This is another personal build diary. Don't expect to see any new engineering.. just my take on a lot of other people's innovation...
Sept 2013 Concept complete and chassis design kicks off.

I had really good results over the past 2 years building/tweaking and enjoying a Lampizator inspired TDA1541a DAC with 6n2p tube output. It was prototyped to death and now that I understand it I want a clean, reference build.

Inspired by Lampizator, I am shamelessly using his case design and level 6 output. This means:
-dual mono power supply,
-5C3S rectifier tubes,
-40H chokes,
-6n2p tubes mounted inverted for easy wiring,
-200u polypropylene filter caps
-separate B+ tranny for each channel

Like many, I have followed ecdesigns and Oliver Mai projects. I decided to use Oliver's Red Baron PCB and Salas shunts. Really nicely done and contains all the stuff that makes for a great tda1541a without all the...

The amps continued to run in and proved to be keepers. Well worth doing some final spit and polish. There was a little hum on one amp and some noise / hash on the tweeters of both channels. Nothing major, but certainly audible at 1 foot.
Using AC filament supply for all but the input tube, I figured I should re read the best practices on wire dressing, hum pots, virtual center tap etc.
Looking back there were some spots to improve.
1. tight wire twist on path from bridge rectifier to first caps. Done, no real change.
2. tight twist on b+ supply to input tube plus added BG 3uF 250v cap right at the tube. No change to noise but love the improvement in sound
3. tight wire twist from psu to b+ on all power tubes plus BG 10uF 250v on each power tube. Like the input tube the BG brought an immediate lowering of noise floor that really brought a finishing to the SQ. Quiet background, micro details and just a smooth rich sound. Not colored, just the way it...

Done! The second went much faster and was playing music in 2 weeks.

Now that they are running I will borrow from the circuit designer's own description of the sound as it really does sum it up..

"There is no substitute for power and that is what this amp has. Complex musical passages are effortlessly reproduced with a natural depth and breadth unmatched by any other amp. Subtle nuances are clearly revealed underneath pounding crescendos.

Striking imaging causes instruments to be layered in a three dimensional sound stage that recreates the experience of a live performance. The music "opens up" and leaps out of the loudspeaker eliminating any box like sound. The most minute and subtle sounds are revealed producing uncanny realism. Musical voices are warm and lifelike yet completely neutral with a razor sharp focus."

In my own words.. incredibly natural. 3D and layered sound. Deep bass with weight creates...

This is the continuation of my personal journey to build my first tube amp.
It was a very happy day yesterday when the first mono bloc powered up and produced music. I was pretty comfortable that I had not made mistakes that would result in smoke, but really did expect some issues with hum, grounding or tube substitution. But nothing! Hum was barely audible with my ear on the speaker or from the chassis. And music played! My first test flight was one channel only driven by a Sony Walkman on a small Totem speaker. Even under these conditions the sound was pretty good, and really started to open up after the first 60 minutes. I was like a proud father
The first picture shows the pair with a Rotel CDP in the middle for scale.
I will not be able to fully know the sound until both are wired, broken in and hooked to the good speakers and source. I think they will be amazing. Already better than the very respectable chip amp they replace. There is a switch...

I am keeping this journal for my own record. There is no new engineering in this project. This is just my own journey while building my first tube amp.

Major milestone achieved today. I finally took the plunge and cut the aluminum. I am very happy with the results. Each and every part fits perfectly.

I planned this project around Front Panel Express. I used their tool designing and redesigning the lay out until I was confident in my layout and fit. Problem is FPE is expensive. Then I saw some comments from other builders that the edge FPE leaves is not really finished. I went searching for a more cost effective solution. I landed on cutting using WaterJet while searching for local CNC shops. There is a company in Toronto close to where I work www.pva-enterprises.com that has an advanced waterjet cutting machine. I exported my FPE file and sent it in for a quote. Given I need a left and a right panel for the 2 mono's I got them to cut both panels...

Over the past few weeks I continued to build out and test the power supplies. I really am pleased with the decision to make each supply as a module that can be fully developed and tested outside the box.

After the success with the first supply for small tubes, I moved on to the power tubes. After abandoning the large Sangamo can caps, I ordered in 8 2200uf snap in caps.. 2 per rail, 4 per monoblock. After they arrived I realized that these things are pretty big. The question was how to securely mount them. I settled on another wood block so they can be mounted securely under the chokes. As before, I mounted them through the wood using some silicon cement. There are some nice mills wire wound bleeder resistors. The B+ power supply design calls for a single center tapped 230v transformer. I had scored 2 pairs of 120v 500va Toroidal transformers. I must admit it took a lot of research and a couple of helpful posts before I was sure that I really had this figured...

In the past few weeks I have made progress on by OTL amps. The wooden bases are finished, and I am very happy with the finish.

I reformed and tested all the big can caps. The Nippon Chemi Caps are fine. The big old Samgmo caps make me too nervous to consider using them. They may be serviceable, but have a high leakage current compared to the Nippons and do not seem to hold a charge. Perhaps I'll use them in some other project. I will buy 2 x 2200 caps for each rail. 4 per mono and 8 in total. This caused yet another redesign of the top plate. I have now got room to place a big heat sink on top. It will disipate heat from bridge rectifiers and big resistors used for soft start.

Finally I started to build. While all point to point wired, the amps will be modular. I am using wood blocks as the base for each power supply circuit. I laid out the supply for the small tube anodes and wired them up. This way the caps are well supported and vibration damped....

I am starting this blog to create a record of my first tube amp project. The project is to build a pair of 110W 6c33c OTL monoblocks based on Bruce Rosenblit's patent. I am starting the blog at the stage that I am well into the project. I started planning and collecting parts well over a year ago and am at the stage where execution is under way.

So how did I end up with this choice? My DIY audio experience got under way with a Peter Daniel chip amp which I enjoy to this day. Along the way I discovered the Lampizator site leading to the creation of a 1541A DAC with 6np2 tube output. When this sprang to life I was hooked on the idea of building a tube amp. I have never actually heard a tube amp. The look is very fundamental. I want to experience the additional nuances in the music reported by tube amp fans.

I wanted to start with something simple but good quality for my first project. I also wanted to keep costs in check. I figured that good quality...