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Simplistic NJFET RIAA

Posted 18th September 2009 at 09:05 PM by RCruz

Originally Posted by RCruz View Post
The offending zener was replaced and now there is no more "woosh"... both channels sound the same with a very low ripple at full volume...

It seems this component is critical for the "transparency" of the shunt.

With two shunts, I notice a much better transient response and wider soundstage (I believe this is due to the better separation provided by the dual mono setup)

I believe a glass low noise zener with a big Ruby ZLH would make a big difference.

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Posted 18th September 2009 at 03:02 AM by tomtt

will this work ?

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HTML Code:
<embed src='' height='320' width='420' bgcolor='0x004481' allowscriptaccess='always' allowfullscreen='true' flashvars='backcolor=0x004481&state=COMPLETED&lightcolor=0xFFFFFF&frontcolor=0xF86700&screencolor=0x000000&
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Posted 15th September 2009 at 09:42 AM by aaaron

After all investing a tiny money i got a new buffer with one made for testing .Then had aidea to multistage it i decided to add one more (like series connected)and tested with my meridian amp and MS speakers ,the result is stunning ,the sound has improved a bit with blend and crisp..........

If anyone need the circuit (again a combination of philips and wadia ) can be shared .

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Audio World of human kind

Posted 15th September 2009 at 09:35 AM by aaaron

There is something special about who love hearing quality music (i mean the sound ) will always have less fear abt the world and have wonderful stamina at thier mind.being my first relaease i thought it would be a welcome blog .

Lots of techno subjects will be added in comming blogs

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leaks are stealing my bass

Posted 13th September 2009 at 01:06 PM by wintermute (Wintermutes Rantings)
Updated 25th November 2009 at 11:11 AM by wintermute (added to speaker category)

I've long known that the boxes for my current three ways are leaky, more than likely incredibly leaky, but I've never bothered doing anything about it because I intended to build some new not leaky cabinets. Well I haven't and it is probably going to be a while before I do, so today I decided to check the impedance curve for the woofer in box. Thanks to Mick (prickears) for his quest to get to the bottom of his 80 Hz suckout I am finally doing something about my leaks!

The design goal (when I changed to vifa 10" drivers from the original 12" plessey's) was a box tuning freq of about 34Hz. When I measured the impedance today for one of the boxes, the tuning freq was in fact about 30Hz much lower than intended and when modeled with that tuning freq, has a very droopy response starting to roll of from about 220Hz, though the f3 is only 2HZ higher than the inteneded model at 36Hz..

So It looks like one of the diy tasks in the comming weeks will be attempting...
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LP 350 Ballast bypass

Posted 12th September 2009 at 09:09 PM by user1701d

Originally Posted by user1701d View Post
I picked up an Infocus LP350 that is missing the lamp. Power supply seems to work fine, all fans come on and green LED comes on . After a short time the LED flashes red (lamp counter or lamp missing ??).After reading a number of posts I need to find a pin on a connector with a voltage around 3 volts and ground the main board side to fool it to think lamp is lit. I only see one hard wired connection between powersupply/ballast board and main board , it has 18 pins and more than one that shows around 3 volts . Any suggestions ?
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Having a 21 month old daughter really eats into your DIY time!

Posted 10th September 2009 at 01:20 PM by wintermute (Wintermutes Rantings)
Updated 25th November 2009 at 11:09 AM by wintermute (added to categories speakers and amplifiers)

I'm finding DIY'ing a very different ball game now that I have started again. The difference being I have a 21 month old daughter now. Gone are the days when I could sit down for 10 hours straight working on something. I have to take on tasks that I can complete in 2 hours (or work on into the night and suffer sleep deprevation!)

Yesterday I did some more sanding on my speaker boxes, I think I could just keep sanding until the 25mm MDF was only 20mm I better stop soon and get on with the veneering.

Tonight I attacked the problem of the switching thump in the amp. I found some 47uF Nichicon FG caps in the cupboard and soldered them into the negative feedback circuit in the preamp. That brought the DC coming out of the gain stage in the preamp down from -1.1V to about -210 mv. I'm not sure if I will try and tackle getting rid of the rest of the dc, but it is a substantial improvement. The cap basically put between the second resistor in the feedback...
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Tube Cad Jurnal Interesting Items

Posted 9th September 2009 at 03:59 PM by DougL

In John's TCJ Blog He featured the Logitech power supplies For Duet and Squeezebox.

Since I have an SB3 and have been thinking of upgrading the power supply, this is a great source of inspiration to me.
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how to make 12 volt dc input 24-0-24 volt ac out put smps transformer

Posted 9th September 2009 at 01:52 PM by vmsmmy

Originally Posted by PJPro View Post
I am currently building my first Chip Amp using the dual mono kit and documenting the build here.

I have just bought a couple of transformers from RS Components. I went for these . Hopefully, they're OK for my needs.

What I would like to do is use a regulated power supply. Can I simply place a separate board between the power supply board
and the amp board? If I can, what would the circuit need to contain?

Many thanks for any advice/recommendations provided.
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The reason my amp has turn on delay....

Posted 6th September 2009 at 12:44 PM by wintermute (Wintermutes Rantings)
Updated 25th November 2009 at 11:08 AM by wintermute (added to amplifiers category)

Well I drilled some holes and wired up the new RCA's on the back of my amp, so now I can switch between direct input (bypassing the preamp) and the normal integrated path. Works nicely and I suspect that the slightly soft top end was actually due to the preamp as the sound seems a bit crisper now on the direct input.

However.... when I switch from direct to via the preamp, or vice versa I get a big thump from the speakers I can avoid if I switch the speakers off but it is not particularly family friendly, especially since I have a 21 month old who will love to switch the switch on and off

So I'm not sure if it is switch contact bounce or perhaps just switch on thump (the fact that there is no thump at all when switching to the off position leads me to belive it is more like a switch on thump), but it is rather anoying. Puts a bit of a damper on an otherwise successful mod. The switch is a center off type, I might have to get a three pole...
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