.. and we need more space ..

The lab is getting a bit full, so I have had to add some storage space to organise the stuff and get it all connected up. I've bought an extra table so I can have my digital scope out working, and to get some of the audio stuff off the floor and put to good use (and so I can play the piano I repaired a little while ago) I thought I would make a 19 inch rack for the effects, amp and so on.

And now, embedded in the new Studio / Lab / Office ... 

.. and this is the other end (the Office-y bit)

Sony STR DB-830 horrors

So I spent a little time working on the Sony problem with the mute. I used a heat gun to warm up various boards, and I found that when heat was applied to a very localised spot on the digital board, it burst into life; only to retreat into silence again a few seconds after the heat is removed.

The issue seems to be either cold joints or an oscillator. So I've replaced the oscillator crystal, and resoldered the cold joints. There's a small repair to the PCB as well, since the removal of the old piezo took a bit of track with it. (cheap PCB). Fingers crossed ...

Denon 1910 horrors

So I ran the diagnostic on the 1910 .. and it is showing that it is version E2, and the communication between the main processor and the sub uCom is broken ...

Sub Error 01 ... No response from Sub-μcom

So the question is what to do about this? It seems that a bunch of people out there in the Interwebs have had issues with the HDMI board on 1910s, and the solution involves changing said HDMI board. Of course finding a 963189004020D might prove difficult.


So my thoughts are:


1) Find one

2) Warm the existing board up with a heat gun to see if it might be the usual lifting of a leg here or there

3) Give up with the amp.

I have a Sony STR-DB830 around the place somewhere, which has a fault on it, but that fault might be easier to fix. Given my setup in the Lab uses the TV to do the video switching, and then the TV feeds out optical digital to the amp, I don't need the HDMI switching capability of the amp any more.
Actually, I just found it in the loft, and it does seem to function. Ta da.

The Sony suffers from a 'mute' issue, which seems to be temperature related. If I turn it on, and leave it on in a warm room for 15 minutes, it suddenly kicks into life. I have fixed that temporarily before with a heat gun on the digital board, and it might be worth a go. The amp has lived a bit, and is not as cosmetically appealing as the Denon, but we need some sounds quick!

On another related topic, I have used a 3.5mm jack on an Echo Dot (version 3) to feed the analogue input of the Denon, which works well.  (assume I can do the same with the Sony, should the need arise) However, the bass is a bit lacking, so I will need to find a way of changing that. There is talk in the fora about an equaliser app for the Echo Dot? I also need a way of making sure that the Echo Dot audio is always audible, so I might be venturing inside it with a glue stick to see if I can get it to feed out through its own speaker as well as feeding out via the 3.5mm jack. Or maybe I mix the audio in the amp with a couple of resistors. Neither approach being very satisfactory tbh.

There is some advice on T'internet that you can put the 3.5mm jack in, and then, when you need to short out the contacts on the socket when you want the internal speaker to work. So that might be when the amp is not listening to the Echo input, or is muted. Maybe I will do something extra to the amp so if it is on, and not muted I will mix the output from the Echo onto the front two channels. Or maybe the centre speaker. Oh, that sounds right. Watch this space.

Reconing the Missions

And another one for the new Lab; I have removed all of the drivers from the Mission 700s. I think these speakers came from a small shop in Chandler's Ford in about 1981; I had re-coned them with some Audax drivers in the 90s, but they have lived a long, sun-drenched life in the Office on Hayling, and it was time to replace them again.

I had a good experience with the Monacor SP210 drivers in the Kef 104 I have in the lounge. They really do kick out a great, punchy but not overstated bass/midrange, so I bought another pair for the Missions.

Since the Lab is white and light Oak, with touches of chrome, the dark ?walnut of the boxes just had to go. I am not really sure how I feel about painting over veneer, but they were a little battered anyway on the corners. I took the trouble of spraying them with a white primer, and then an eggshell finish white. The new drivers went in after a couple of weeks of the enclosure drying in the garage, and they seem to have come out quite well:

Sounds? Well, having a bit of trouble with the amp at the moment. It doesn't seem to be decoding a digital input. I have the optical output from the TV, and I was hoping that the amp would just pick it up and drive the speakers, but it doesn't. I wonder if the HDMI board has left the planet when the old TV HDMI input went bang.

I did plug the Alexa into the analogue input on the amp, and I listened to Bon Jovi's Wanted Dead or Alive through the speakers. They work, and really very well.

All change for the house network

I gave up trying to get DD-WRT working successfully on the DIR-868L wifi hub. It was working quite well, except all of the Amazon Echo devices would occasionally disconnect, and I had a time getting Android phones working. The wired functionality was all fine, but that's not good enough.

So, I have now moved to buying another server, suitable for running pfSense on. This distro is a simple install of a BSD box that is configured as a firewall, router, VPN, VLAN-aware and capable box. So I have now re-architected the house solution to use that box instead ..

Tri-amping

For the New Lab, I thought it would be a good time to improve the sound system a bit. I have a pair of Kef Concerto speakers from the 70s, I have the power amp boards from the project a couple of years ago, I have a donor home cinema amp or two so some bits come together.

I was sorting out someone's lousy sounding hi-fi on Hayling last year or so, where they said the sound was muffled. It turned out that their speakers were bi-amp capable, and they were only driving the bass part. I'd wired them in properly, and that thought was in the back of my mind. I liked the sound of those bi-amped speakers, and it stuck with me. I did some research online, found that there were people who did recommend tri-amping as well as bi-amping for smaller bookshelf-y sized speakers, so I was ready for it.

Then an offer from Seeed studios dropped in the mail box for 5 10cm square boards for about a tenner including postage, so I went for it.

This is the Linkwitz filter - two required, one for each channel. The idea is that it is fed from a regular 700mV kind of level output from a pre-amp or mixer, has some fairly steep active filters that provide the low end, the mid-band and the high end signals to discrete power amplifiers, which are then wired directly to the speaker drive units (maybe with an inline fuse in a vain attempt to save the life of a speaker cone if the amp decides to fail in dramatic fashion).

KiCad .. !

Well, kind of getting used to it. Thought I would design something and do a layout .. so here is the schematic. This is a good ol' PTH (that's Pin Thru Hole for those of you who are not suffering from the effects of age on the eyes, and can use SMT devices without a stereo travelling microscope) design of an MSF Receiver. MSF is the time signal broadcast from the National Physics Lab. now from somewhere in Cumbria at 60KHz. So a simple receiver with an external ferrite rod and MW coil feeds into a simple circuit to recover a digital signal.

.. and here the layout!

It's really good. Functionality is good - of course it is very different to Eagle, and finding ones way around the menus while adopting a new workflow ..  but it performs well, has some really useful features and quite a few bits I like a lot.

Now there are a couple of things I don't like about KiCad, but getting used to them.

1) No curved traces! Really, guys. My signature curvy traces no more?
2) No embedded autorouter. Well, to be honest I can route well enough and quickly enough not to worry me. The push/shove router works very well, and you can buy plug-in autorouters, but I am talking myself out of them at the mo.

I like the decoupling of the component from the footprint used. It makes the schematic more of an abstract representation of the function of the circuit rather than a particular instance - which helps the mind to keep open.