[DigIndig]

I've been lurking here for awhile, but finally decided to officially join. And I guess I have to introduce myself.

I'm Greg, and I've been an audiophile for as long as I can remember. I grew up listening to my father's Dual turntable, Kenwood receiver, and AR 2-ax speakers. I eventually inherited that system when my father upgraded, though he got me new AR bookshelf speakers and kept the 2-axs. I've made modest upgrades over the years, but I'm extremely picky, and I've been looking for new speakers for 15ish years.  I didn't find anything I really liked until I heard the NX-Oticas earlier this year, and knew they were the real deal. Hence, I'm here.

While I'm waiting for the drivers to be back in stock, I'm working on several DIY projects to keep me occupied:

- I'm rebuilding my father's AR-2ax by replacing the pots, the capacitors, and the driver seals. They were long ago replaced by a pair of Polk Audio VR-40s in his system - handpicked by me - but they've been stored and well cared for all these years. I've finished one, have three to go (he had two pairs for surround).
- I'm building an Elekit TU-8800 tube amp to pair with the NX-Oticas.
- I'm building a pair of the Folsom EC7293 chip amps. These are the successor to the EC7297 chip amp he designed several years ago (and I believe Danny may still be using). Jeremy claims they are even better, though I admit I don't really have a reference point.  If anything, it's a cheaper starter project before I tackle the TU-8800.

In addition to DIY, I'm also a huge music fan (and taper), and I run professional sound on the side. You can find a few recordings of mine on the Live Music Archive, including one of Danny's favorites, Vienna Teng, who he still uses as one of his demo tracks. When I visited GR Research, I gave Danny a few new live Vienna tracks to compare to the material he had.  I think it went over well.

So that's me in a nutshell. Happy to join the community, and can't wait to build my own pair of NX-Oticas.

[Skilly]

Welcome to AC Greg. I look forward to hearing about your builds. Please share the good the bad and the ugly... but only good photos.

[Hobbsmeerkat]

Welcome to AC!

[ArthurDent]

Greetings & Welcome to AC Greg   

[DigIndig]

Welcome to AC Greg. I look forward to hearing about your builds. Please share the good the bad and the ugly... but only good photos.

I'll try, though I'm not one to stop mid-project and take lots of photos.

[Phil A]

Welcome!

[DigIndig]

An update of sorts on my EC7293 chip amp build. Over the past few weeks, I've had a little time to work on this.

I built the power supplies a few weeks ago. Still untested, but it's coming soon. I decided to get a variac to control the voltage in case I did something wrong, and decided to rethink my dual mono plans with a pair of dual mono blocks. I'm using the 2U Dissipante cases from Modu, and I had them CNC a pair of back panels to my spec while I was ordering a second case.



This past weekend I finally had a few hours to start on the amplifiers themselves. I built the light module pretty easily (sorry, no pictures), and then tackled the amp boards themselves while I waited for a package to arrive. I tested the photocells to make sure they were working properly, but again the boards haven't been tested yet. I still need to drill the heatsinks and mount the chips before I even attempt that!

[Danny Richie]

Hey Greg, welcome to AC.

[Folsom]

I like the way things are developing here. Welcome to the forum.

[DigIndig]

I like the way things are developing here. Welcome to the forum.

Thanks, Jeremy. Last weekend I got everything laid out to drill and tap my heatsinks for the amps, but needed a different tap. I mocked up the build, and put two notches in the side of the baseplate with a hacksaw to accommodate the standoffs on the amp board and get the chips flush on the heatsink. Then marked the locations where screws through the chip holes would go. Now I just need to determine where the clip screws will be, drill and tap the holes, mount the chips, and then proceed with testing.

I also decided to add soft starts and speaker protection circuits to my build, so ordered those, and now I'm waiting. Backorders on two components mean I'll have to wait until the end of the month to make progress with those. No new pictures on that front (yet).

This weekend I finally built the TU-8800.  I spent all of Friday evening and most of Saturday on the build, only to be rewarded with...nothing. Sunday morning I finally had a chance to do some test probing, and narrowed down the first problem to the AC power circuit. Turned out when I did the final soldering late Saturday, the board was at an angle and the solder didn't flow perfectly around the solder joints, leaving a few opens. I went back and redid the solder on a few terminals, and the amp fired up right away. I did some more testing expecting to find another issue, but all was well (an honest surprise). I'm now testing inputs and the different modes to test the various functions (no issues so far). Everything worked! The only thing I need to address is a slight hum/crackling when I touch the volume control. I knew to expect that from the instructions, but they didn't provide a good solution if I follow the rest of the instructions. To whit, they suggest scraping to bare metal where the nut goes on the volume shaft to make a connection to chassis ground, but this model has a plastic diffuser that is supposed to go behind the washer and nut. I'm thinking of making a grounding strap instead and see if that solves the problem in a more elegant way: use a lug terminal to loop around the volume shaft and connect the other end to one of the screws in the chassis. With enough slack it should be easy to slip on and off. I suppose I could also just make a small scrape and put the washer behind the diffuser. Once I've got it working well and broken in, I'll see about installing the upgraded input capacitors I bought.









So, one amp down for the NX-Otica's, two to go!

[johnzhel]

@DigIndig Hi Greg, I am new to this forum. How are your TU-8800 tube amp and NX-Otica? I am thinking about building my very first tube amp.