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New scope - update

Posted 25th November 2010 at 01:36 AM by abraxalito

The Tekway is still working well and survived the 35oC temperatures of Hangzhou's summer despite having no internal fan. That is, apart from its CMOS store of the date/time, which for some reason now thinks the year is 2011.

Someone on the EEVBlog just posted this - I haven't read it thoroughly yet but I intend to find out if I can upgrade to 200MHz. Looks promising

Upgrading DST1102B to 200MHz bandwidth
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JBL L100 Homage

Posted 20th November 2010 at 04:55 AM by DougL
Updated 11th February 2011 at 04:50 AM by DougL

I got into audio my freshman year of collage in 1973. While I hated the "West coast sound",
The JBL L100 looked great, and had a great woofer. It is also higher efficiency than most.
HTGuide did a Thread on redesigning the XO and made a very appealing speaker.
I looked up the woofer and its 88 db efficient. So much for perception of efficiency.

My thought was to design a 3 way speaker that is ultra low distortion, 50Hz F6, and 93db efficiency. Borrowing the L100 concept, Driver compliment 12" woofer, 4" mid-range and OS compression driver.

There are at least 3 drivers in the 4" class with 93db Audax HM100Z0 4" Aerogel Mid-range ,
Fostex FE126En 4" Full Range
I already have and love MP14RCY/P in ob, but they are only 90db sensitivity.

The B&C 3/4" or 1/2" CD look like they might be a perfect match. Sure beats a 2" paper tweeter.
Even a B&C...
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Keantoken C-multiplier

Posted 17th November 2010 at 02:45 PM by klewis
Updated 7th January 2011 at 01:00 AM by klewis

voltage multiplyer: Cockcroft-walton
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More transparency in active speakers - part II

Posted 15th November 2010 at 12:59 PM by abraxalito
Updated 5th March 2012 at 02:58 AM by abraxalito

Its not something I claim originality for, this use of Cat6 cable for running to speakers. What though I believe is original is combining the function of speaker cable with the sharing resistors - I've seen that nowhere else. Remember guys, you saw it here first

Not only does this save on having low value fairly high power resistors but it comes with another benefit which suits diyers. That's the fact that the amps can be easily tested separately - they're not going to be in parallel until the drive unit is connected to the output, since the cables join together only at the far end, at the terminals of the driver. I've certainly found this an advantage in development - the individual gains I've checked with a multimeter between the outputs when playing a 400Hz sinewave. This frequency was chosen because I'm too lazy to check the frequency response of my multimeter and I wanted a mid-range test.

The gains of the individual chip amps do need matching very...
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More transparency in active speakers

Posted 13th November 2010 at 03:23 AM by abraxalito
Updated 5th March 2012 at 03:05 AM by abraxalito

Those of you who read my earlier posts about improving my Fayou actives might have realised by now I'm a bit fanatical about grounding and its effect on sound quality. I had an idea - could a system be put together without any ground at all, and might this solve many of the sound quality issues I've found in my setup? I could only find out by trying it. So, the idea was born - 'Goundless Sound'.

First up, a groundless amplifier is just another name for a balanced, or bridged design, at least in respect of the output being balanced. A truly balanced amp would also need a balanced input - that's not really ground-breaking (pardon the pun, could not resist) either. Putting the two together is hardly rocket science. But I decided on a few twists - more about those in just a moment.

Convention is a useful thing. Ponder a world without convention in respect of computer keyboards - Asus and Toshiba having one layout of the keys on their notebooks, Dell and Lenovo...
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Feedback, or how to be late and be on time the same time, all the time.

Posted 3rd November 2010 at 05:19 AM by jan.didden
Updated 3rd November 2010 at 10:20 AM by jan.didden

Just a couple of days ago I posted something to try to debunk that tired old myth that 'feedback always comes too late and therefor can't work'. Apart from the fact that obviously it does work, which makes the first statement pretty stupid to begin with, here's my take on it.

The myth may result from an often repeated misconception that feedback comes 'after the fact' and therefore always comes too late.
This has been shown to not be the case over and over again but if you have no engineering background it may be difficult to grasp the concept. Let me try to help.

Obviously, there is a signal delay in an amp from input to output and back to the input through the feedback loop. Since the feedback loop is generally a pair of resistors, the bulk of the delay is in the amp. That is the case both in non-feedback as well as in feedback amps. Such delays are very small, often fractions of a microsecond, and in this context can be ignored.

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meridian 506 laser problem

Posted 28th October 2010 at 11:10 AM by meridianqq

I have concluded that I need to replace the cdm12.4 in my meridian 506. Has anyone got picture or instructions on how to go about taking it all apart?
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Salas low shunt for DAC,Clock, Pre Phono

Posted 18th October 2010 at 08:43 AM by quanghao

Salas low shunt for DAC,Clock, Pre Phono
Out 1.5 to 5V
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Help to Modify Profire 2626

Posted 18th October 2010 at 05:13 AM by hawg4life

I wont modify my Profire 2626 interface but don't know where to find my ad converter plus in and out put op amps which capacitors do I change for a better sound and what types can I put in it, could I use film capacitors please can someone help. The caps say Suncap 100uf 25v and some 35 volts whats the best I can use I would love to use film caps if possible or the best electro brands. The power supply is on the board by its' self in the top right corner and the master volume is in the bottom right under the green panel. Can anyone tell me what to look for or how tho modify this board for smoothest sound. Thanks!!!
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Squeezebox SB3 update 2

Posted 15th October 2010 at 08:56 AM by audi0

I got the last capacitor for the analogue stage upgrade in the mail today, I had a couple of hours of spare time so made a start. DE-soldering of surface mount components has got to be the worst job! It's slow painstaking work avoiding damage to pads and tracks, and this took the longest part of the job. A slight modification to the IC adapter was necessary to avoid hitting a capacitor otherwise reassembly was simple.
Plugged it in and away it went (sometimes I surprise myself!)
Nice sound immediately and I'm sure its only going to get better once the Elna's burn in!
I was surprised how sturdy the adapter is, there was no issue plugging in the IC, so chip rolling would be extremely easy.
A worthwhile modification? Yes I think so!
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