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Old

TI marches steadily down the road to oblivion

Posted 23rd October 2013 at 12:20 AM by abraxalito

But hey, its stock is 30% up on the year!

http://www.testosteronepit.com/home/...verpriced.html

Wolf is a little bit too polite in his analysis of TI's woes - #1 is crappy strategic thinking.
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Old

Prototype stereo balanced passive filter for Ozone

Posted 14th October 2013 at 06:57 AM by abraxalito
Updated 27th November 2013 at 01:42 AM by abraxalito

Here's my first stab at an affordable yet screened passive filter using off-the-shelf inductors. Its a 17th order quasi-Chebyshev using 8 equal valued series L and 9 shunt caps achieving slightly better than 50dB rejection at 24.1kHz.

Update - this might be the first and last filter I build with these Coilcraft inductors. (If anyone's interested, the part no. is LPS6235-335). Reason being - on trying to order more, the price got hiked more than 100%. Originally these were attractive because on Taobao there was a source selling well below the manufacturer's list, but that seems to have dried up. At the list price in USD, there are other alternatives potentially better value. However none with the same inductance (3.3mH). The key feature is the Q - the Coilcrafts have a Q around 40 at 20kHz - this is very hard to beat in such a small package. As a reference, my pot-core hand-wound inductors have a Q about 160 but they're huge in comparison, so these tiny inductors are actually...
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Old

Wharfedale Dovedale cone rubber repair

Posted 10th October 2013 at 11:28 PM by hbc

After the Magisters went I started missing them. Much irrational thought later I decided that I needed some Dovedales. It may be some left over residual memory of some super 8s I had when I was young, they were very nice despite the lack of tweeter (retrospective young thought). The big Dovedale woofers look similar with the green felt, bit nervous of those strange pink domes though... Anyway, eventually "won" some with mint drivers slightly tatty boxes. Long story short the rubber had got stiff, but not yet brittle.

Sulk, got the Magnums... (must have bass now). After much research and thought, the Dovedales don't seem to be a standard size for foam, and I had got to the point of contemplating cutting away some of the cone to fit a flat foam. I was tidying up the garden when I found a 700 inner tube I had changed recently.
At this point I thought what have I got to loose, so gave it a good wash, (lots of washing up liquid applied neat), chopped out the valve...
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Old

Introducing the Ozone DAC platform

Posted 9th October 2013 at 11:51 AM by abraxalito

The time has come to talk about the overall aim of my DAC developments - a modular DAC platform for DIYers and audio systems integrators. By this word 'platform' I mean this isn't going to be presented as a single end-to-end design that you can order up from a friendly reseller. Nor is this an 'open source' design, although it is open to anyone to use or adapt with no restrictions. Rather this is a DIYer's DAC architecture a series of interconnected modules that are subsystems from which an audiophile grade DAC can be assembled.

When I say 'audiophile grade' what I mean is this is a design optimized for aural satisfaction, not for the numbers. To be even more specific, its been optimized to give the highest perceived dynamics (within the limitations of the chosen DAC chip) rather than the lowest THD+N and flattest FR. If you're looking for ODAC-type measurements, feel free to move along now That's not to say measurements have been ignored, rather they're very much in the...
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Old

Passive line level filters.

Posted 6th October 2013 at 02:27 AM by MITsound (Dedicated satellite/sub combo)

Tried out fmod high and low pass filters to feed inputs on a 300B integrated and Nait 5 , used to drive mid&treble horns, and 15" trace Elliot woofers , respectively. All mounted on large(ish) open baffle. 6db highpass @ 900hz leaves out enough bass and eq's a "hump" in the mid's response. Instead of a series cap for the highpass leg of this "filtered rca splitter", would I parallel another cap from hot to neutral to create a low pass? This is being done with 3 rca sockets in a project box per channel as I don't wish to mod the original amps and to ease cap swapping which past speaker level crossovers have proven irresistible for me to avoid revising. I do wish to maintain 1st order filtering, for the sake of fixing a couple of minor "humps" and "knees" in these drivers' responses. Bear in mind I'm very new to the electrical side of audio. Any help welcome.
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Old

Goodmans Magnum and the Valve sound...

Posted 30th September 2013 at 11:07 PM by hbc

To try to recreate the Magister experience I hooked up the Magnums to the little ECL86 amp mentioned previously. I was greeted again with enormous deep bass, but not as happy over all, a rather lumpy frequency response, and a big question, what's going on... So I hooked up my Hybrid amp and the Magnums sounded a bit more normal, but the bass was considerably reigned in, disappointingly.

I think the Magnums like being back against the wall, they seem happy there and the in room response is now quite civilised with a nice boom free sound and bass is only there when it should be.

Still confused, had the ECL86 on the bench to measure to try and find out what's up. The frequency response looks a bit rolled off to the bottom, so no help there, but the treble peak is looking quite promising, explaining the "prominent" treble. After some wriggling the little amp surrendered its output impedance, all be it with significant 50Hz artefacts.

The output...
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hbc
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Old

Goodmans Magnum K2 - SL cone rescue

Posted 26th September 2013 at 11:04 PM by hbc

I recently got some Goodmans Magnums K2, and SLs, in my quest for lovely bass, experienced when I had some Magisters, 6 months ago, but in a smaller box. Like the Magisters the plastic cover of the woofer had started to de-laminate. The K2 had suffered more, so embolden by having 2 pairs of speakers with apparently identical woofers, I decided to have a go at fixing them.

For whatever reason I decided to attack them with my hot air gun. The black material is softened quickly but so did the dust cap glue, so I took that off, and then I just tried to push the soft plastic back on to the cone, and it stuck, a bit at a time with my finger. I then put some hotmelt glue around the edge of the lamination to try to give it some more support. Then I heated up the edge of the lamination and around the back of the dome and put it back on... No idea if it will hold but it was quite easy to do.

The woofers between these K2s and SLs are different, the resonance of the SL...
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Old

The new Tube-I-zator V3.1

Posted 16th September 2013 at 05:28 PM by dvb projekt
Updated 11th July 2014 at 03:21 PM by dvb projekt (Stock status update)

The new Tube-I-zator V3.1

Click the image to open in full size.

The evolution brings the following changes:

- Anode PSU with Salas SSHV Shunt Reg. onboard
- External B+ Input for usage with other Anode PSU
- Heater PSU with C-R-C filtering
- Heater PSU with Softstart circuit
- Heater PSU Power LED

- Design failures corrected

Thanks to John (-ecdesigns-) for the following suggestions!

- Grid stoppers to prevent unwanted oscillations
- Bias current injection for TDA1541A usage
- Pull-down resistors to keep the coupling cap output at GND-potential

Still on the Module:

- Heater switch for 6N2P or 12AX7 usage



An example for a balanced use (e.g. Bufalo II), you could see HERE.



The PCB has the following data:

Material: FR4 - 2mm
...
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File Type: zip Tube-I-zator V3.1 - BOM.xls.zip (7.6 KB, 212 views)
File Type: pdf Tube-I-zator V3.1.pdf (835.7 KB, 448 views)
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Old

My Ref Music Server - Lampizator meets Red Baron

Posted 11th September 2013 at 01:31 AM by wlowes
Updated 3rd January 2014 at 03:14 AM by wlowes

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...
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Old

Soundcard measurements with ASIO

Posted 7th September 2013 at 09:51 AM by alexcp (My DIY projects)
Updated 17th February 2014 at 05:08 AM by alexcp

I talked earlier about soundcard measurements, and here is some news: Pioneer Hill Software updated SpectraPLUS 5 so that it can now use ASIO.

ASIO (Audio Stream Input-Output) replaces Windows' own MME (MultiMedia Extensions) or DirectSound. As far as I understand, the beauty of ASIO is that it bypasses Windows Mixer and thus doesn't bring any issues associated with sample rate conversion or level adjustment.

The ASIO drivers that came with my E-MU 0204 crash every time (on Windows 7 and WIndows 8). Thankfully, there is ASIO4ALL, which works well for me.

First picture shows two spectra taken with SpectraPLUS: red is the E-MU 0204 output fed directly into E-MU's input; and blue is the output of the E-MU fed into Pete Millett's interface, output of the interface fed to the input of the interface, and then back to the sound card. THD+N is 0.000781% is the first case and 0.001272% in the second.

Next two screenshots are THD+N vs frequency...
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