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Passive fiilters - musings on inductors and topologies

Posted 5th August 2013 at 12:58 AM by abraxalito
Updated 5th August 2013 at 01:02 AM by abraxalito

I've spent many hours recently poring over webpages and catalogues of inductors, looking for the best bang-for-the-buck in relation to anti-imaging filter inductors.

The gold standard, where performance is uppermost and cost and size are subsidiary, looks to be still the gapped ferrite pot cores I started out using. Their disadvantages are they need to be custom wound, not being available off-the-shelf, and their consequent higher cost. They also produce relatively bulky filters when a dozen or more are called for in a design. I've found nothing to beat them in performance, particularly accuracy and repeatability of their value and in terms of achievable Q (I've seen 500-plus in some cases on my meter).

I do hanker after a more portable and easier to replicate design though hence my investigations into cheaper alternatives.

Right down the bottom of the pile are the bobbin-wound coils, available in a wide variety of values here, at stunningly affordable...
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The non passive pre becomes interesting

Posted 3rd August 2013 at 09:03 AM by hbc

Lots going on, my making things mojo has been busy. I have been reading 6 moons, and was interested by the idea of the directly heated triode preamp which sounds quite well apparently, and also repelled by the thought of using a huge output tube, slightly. So after some thought, I realised that the old battery radios used the directly heated ones, so a few weeks later some 3A5s were winging them selves to me.

Oh, (sigh) I had spent some time tweaking it first (the not passive pre) the most exciting feature was that the copied guru circuit pulled the output cathode to the HT rail when the heater is turned off! (I have big reservoir caps and small bleed). To be fair guru circuit is direct coupled so things are all over the place, but Anyway.

I decided to graft in the 3A5 in to this circuit, which was simple in principle, but ended up with a complete redesign of the power supply several times, as the addition of that one little tube hugely increased the heat generated...
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Old

Little Big Amp

Posted 3rd August 2013 at 04:55 AM by homeskillet (Journey to the Center of the Circuits of Homeskillet)
Updated 5th August 2013 at 05:34 AM by homeskillet

Hi. Here continues the tinkering continued from the forum post:
http://www.diyaudio.com/forums/tubes...-feedback.html

I took out that EF184 and the plate to plate feedback loop since I read that devices with a more stable performance without feedback sounded better once it was applied than devices that rely on feedback for their very operation. This seemed about right and I was tiring of the sound a bit.

The plate to plate feedback was the only way I could find to stabilize the EF184 and 6550 in this basic configuration and give any reasonable results and wiring it satisfied my curiosity so apart it came.

I replaced V1 with a 12AT7 and wired it in parallel since I figured it could use all the help it could get to drive the 6550.

The global feedback is my first attempt at current feedback. It's basically part of my first attempt at feedback at all.

I...
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Old

Stumbled upon btinterface

Posted 16th July 2013 at 07:32 PM by merlin2069er
Updated 19th July 2013 at 11:36 AM by merlin2069er (adding links...)

I was browsing the google play store one day when I came across something called BTInterface.

Anyways, that free btinterface program led me to btinterface.com where I watched a few of the videos posted. I was immediately impressed with the possibilities. So I bought an android phone, and installed the btinterface app.

I picked up a couple of arduinos (mega 1280) about $12 each, and bt modules, about $8 on ebay, and also picked up some relays to fool around with (about $12) and jumper cables...

BTInterface will allow you to connect to a bt module, then send commands to it. You need a sketch on the arduino to do something with those commands.

BTInterface being a bit limited in what it can do - I purchased basic4android.

So, with basic4android I put together a few screens, on a couple of tabs. The first tab, "Sources" - allows you to edit the name and select a source (these names are saved to an internal...
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Old

Interesting Horn info

Posted 11th July 2013 at 10:55 PM by DougL

In this post the User clams that the Compression driver Atlas PD5V is a derivative of the WE555, which was good down to 100 Hz


http://www.diyaudio.com/forums/multi...ml#post3558010

There was also mention of an AES paper on how to create a phase plug for a cone driver.

Based on Romy's ideas on a mid-bass horn, This might cover down to 200 / 300 hz to transition to a Tapped horn.
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I2S transcoder

Posted 7th July 2013 at 12:57 PM by abraxalito
Updated 16th September 2013 at 01:32 AM by abraxalito (Schematics added, pic of 2nd build added)

Here's a circuit that's been a long time in gestation - some logic that converts I2S from 64fs (32bits per sample) down to 32fs (16bits).

Almost all the S/PDIF receiver chips nowadays output a bit clock at 64fs (2.8MHz for RBCD) because the format has the potential to support up to 24bits. When being driven from a CD player though, there's no chance of any useful information occupying those spare bits. As my interest is to run all signals as slow as possible to keep noise to the absolute minimum, 64fs to me is profligate generation of RF when 32fs will do the job. But only the WM8805 supports this format and then only when software programmed.

The other reason for wanting the slower bit clock is that my LAID design relies on shift registers and the 32fs clock gives me twice as good utilization of the serial storage - no bits are being wasted on zero padding.

This circuit is designed to do the job with the fewest standard logic chips I could manage...
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Better than a box of chocolates

Posted 25th June 2013 at 06:17 PM by alexcp (My DIY projects)
Updated 25th June 2013 at 08:27 PM by alexcp

Got this today on the cheap - a box of 6N1P-VI, made in 1988, all new in authentic factory packaging. It is likely to keep me entertained for quite some time

Note: the PDF attachment is a scan of the factory three page insert from the box. It is in Russian and contains the pinout and electrical and limiting parameters of the tube but NO CURVES.
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File Type: pdf 6N1P.pdf (6.03 MB, 108 views)
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High resolution pictures of my projects

Posted 19th June 2013 at 10:54 AM by dvb projekt

From today you will find high resolution pictures

of all my projects at my

flickr

Webside




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Old

The new Red Baron DAC Module V5.0

Posted 19th June 2013 at 10:30 AM by dvb projekt
Updated 11th July 2014 at 03:22 PM by dvb projekt (Stock status updated)

The new Red Baron
V5.0


Click the image to open in full size.


The evolution brings the following changes

- Jumper for I2S / simultaneous mode
- latest 3.3V attenuator for I2S & simultaneous mode (by -ecdesigns-)
- free running DEM oscillator (by -ecdesigns-)
- additional U.FL pads for I2S & simultaneous mode
- Separate U.FL-GND route to Digital-GND


Still on the module

- Separate I2S-GND route to Digital-GND
- Separate Analog Output GND route
- Separate GND route for active divider decoupling caps to Analog-GND
- Modified active divider decoupling pads for better SMD 1210 caps soldering
- Un-interrupted ground plane
- Direct shunt voltage inputs with shortest onboard traces
- I2S In-/Outputs with shortest onboard traces
- Onboard Grounded-Gate MOSFET Current Buffer I/V Stage
(-ecdesigns-
...
Attached Files
File Type: pdf Red Baron V5.0.pdf (29.7 KB, 764 views)
File Type: zip TDA1541A Project - BOM - for The Red Baron V5.xls.zip (9.2 KB, 433 views)
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Old

Reference TDA1541A DAC Modules

Posted 14th June 2013 at 10:51 AM by dvb projekt
Updated 27th September 2013 at 01:27 PM by dvb projekt

TDA1541A DAC Module

Click the image to open in full size.
Click the image to open in full size.

- separate TL431 Shunt regulators for each voltage line
- independent voltage rail for the DEM reclock circuit
- I2S attenuator circuit
- shortest possible position for decoupling caps
- separate ground line for decoupling caps
- Ground plane
- 2mm pcb
- Immersion Gold
- green soldermask on both side
- 35m copper weight
- Board size 125mm x 125mm

in Stock

The price is:

TDA1541A DAC Module: $9

Worldwide shipping: $ 9
Europe shipping: $ 5
paypal fee: 3,9%

Shipping insurance on buyers request!


----------

The Ultra High Speed Buffer Module will be shipped "ready to use",
with three NC7SZ125 chips
...
Attached Files
File Type: pdf Reference TDA1541A DAC V2.3.pdf (559.7 KB, 402 views)
File Type: zip TDA1541A Project-BOM-Final.xls.zip (8.0 KB, 149 views)
File Type: pdf Takamisawa NA-Type.pdf (153.3 KB, 482 views)
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