future kit plans?

Raj · « **on:** 7 Feb 2003, 08:14 pm »

Hi David,

Any details of any other White Noise kits planned for the future? A no compromise up-sampling DAC would be nice!

Thanks
Raj

davidw · « **Reply #1 on:** 9 Feb 2003, 04:10 pm »

Raj,
I've had quite a few requests for a DAC so I'm certainly thinking about it. As regards other new products there will soon be an active crossover cased kit ( 2 xovers, 1 cascode psu ) and a little while later a mains switching/soft start module. The latter allows you to swtich high ciurrent mains using a small, low current control switch as well as providing soft start. My soft start module will be fail safe, unlike most others which fail by burning up ( literally ) the curent limiting resistors when the shorting relay fails ( as it will after a few years ). There are obviously other projects in hand but I don't want to publicise these at present.

David

davidw · « **Reply #2 on:** 19 Jan 2004, 10:10 pm »

Just a few lines on two new products in the catalogue, and one close to fruition. The two new products are the crystal controlled turntable power supply and the soundcard/spectrum analyser software.
The turntable power supply puts out 15watts or so of 50/60Hz power at 220/110V so it'll drive big ( 12watt ) motors like the ones on the Garrard 301 and 401s as well as the more normal 2-3watt types. You can also use the supply as a source of clean and pure power for preamps, CD players, DACs etc. I'll probably do a higher power version of the supply with three or four ouput sockets so that everything except the power amp can benefit from a pure and stable supply.
The audio spectrum analyser consists of a 24bit 96kHz soundcard, third party software, and a White Noise instruction manual. The latter is necessary because the manual that comes with the software assumes too high a level knowledge of signal processing ( a common failing with software developers ). I might also do a little preamp with a hardware gain control and protection circuitry for the soundcard input. Upgrading the opamps on the souncard is also a possibility.
Finally, the article by Dave Stocks in the current HiFi World on remote volume controls reminded me that I did something similar for a customer a year or two back. The difference was that I used mosfets rather than bipolars in the controller, so that as well as driving motorized potentiometers it would aslo drive a motor powerful enough for a stepped attenuator. This works very well with my 24 way stepped attenuators; the only minor drawback is that there's no manual control because the motor gearing can't be turned backwards with a knob. I tried, without real success, to make a slipping clutch that would enable manual as well as remote control. You can buy ready made clutches but they're very expensive ( £60 or so ). Anyway, if there's enough interest I'll make the controller and motorized potentiometer or controller and motor ( for stepped attenuator ) available as a kit.

David

Jimmy_B · « **Reply #3 on:** 20 Jan 2004, 02:14 pm »

If you're looking at a DAC or other digital based products try Wolfson chips if you fancy going the Scottish route.

http://www.wolfsonmicro.com

Currently a few well known British Hifi companies are using these so they must sound pretty good.

Oh yeah, I do work for them as you might have guessed !!

Sorry

J

davidw · « **Reply #4 on:** 18 Sep 2004, 10:54 am »

There are two or three new products available now and in the catalogue soon. The first is a soft start unit which stops the lights dimming when you switch on a high power amp, and allows you to use a tiny mains switch for even the largest transformers - the "real" mains switching is done by a high current relay. The unit also includes MOV surge protectors and a remote on facility - you can turn on the power amp from the preamp or what have you by sending a 12V switch on signal.
Now that so many opamps are only available in so8 surface mount packages I've done a so8 to dil adaptor so that you can plug the surface mount opamp into an ordinary ic socket. I know that these are available elsewhere but you either have to pay an exhorbitant price or send to the US for them - even then they're not cheap. Mine cost £1.50 each including uk postage.
Constant current source ics are very useful and widely used in White Noise products. I'd use them even more widely if I could get high enough voltage and current ratings. I've done a tiny, surface mount, two terminal, constant current source pcb to solve this problem. One obvious use of this device is to replace the two 2k2 2W resistors feeding the opamp power supply in the audiophile MOS125 and the MOS250. This will make the PSSR of the circuitry powering the opamp effectively infinite. This is still worth doing even if you have a separate psu for the opamp.

Raj · « **Reply #5 on:** 18 Sep 2004, 08:46 pm »

Hi David,

do you have a price yet for the surge protection, and current source kits?

thanks
Raja

davidw · « **Reply #6 on:** 22 Sep 2004, 06:26 pm »

Raja,
I've just done the pricing for the new kits. The soft start/remote start/surge supressor kit is £40 and the constant current source kits are £3.50 each.

davidw · « **Reply #7 on:** 15 Nov 2004, 07:20 pm »

Some more additions. I've done an adaptor so that you can convert two single surface mount opamps into a dual opamp dil 8 pin plug in format. One ic sits on top of the board and one on the bottom. So you can make a "dual" opa627, AD825, or what have you. This will have gold plated pins and be available in about 3 weeks. At about the same time I'll start fitting the 8pin soic to 8 pin dip adaptor with gold plated pins and raising the price a little to reflect this.
There is now a headphone amplifier kit with a single pair of phono inputs, and Alps volume control pot, gold plated 1/4" jack, and LM6171 opamps. Its very well documented in the diy section of the headfi forum. It costs £150 for a kit or £200 assembled, boxed, and tested.
The cascode power supply has now been upgraded to give lower noise and even better ripple rejection and regulation. The audiophile version uses LM1086 low dropout regulators exclusively, whilst the standard version uses LM317s, and is true "dual mono". There are two completely independent single ended power supplies which can be used as such, even to the extent of giving two different output voltages, or connected in series to give a split rail power supply. The price of the standard version is unchanged whilst the audiophile version will cost a little more.
New versions of three more existing products will be announced before christmas.

davidw · « **Reply #8 on:** 24 Jan 2005, 12:14 am »

Just a quickie to let those of you who don't follow headfi know that there is a new version of the buffer amplifier and headphone amplifier available. Both of them now have a capacitance multiplier ahead of the rail splitter, which makes the amplifier performance less dependent on the power supply. Both units now have two pairs of output transistors per channel instead of one. This doubles the peak output current and reduces the already very low distortion still further. The volume control and headphone jack of the headphone amplifier are now pcb mounted, which saves on point to point wiring. The audiophile versions of both amplifiers now use LM6171 opamps rather than OPA627s.

davidw · « **Reply #9 on:** 11 Feb 2006, 09:08 pm »

A couple more new product announcements.

The phono stage has been upgraded. The new version supercedes the old one, which is no longer available. The new version uses discrete component capacitance multipliers ( 12 in total ) to feed the opamps; and discrete component, zero feedback, voltage regulators to feed the capacitance multipliers. The discrete component capacitance multipliers and regulators have replaced all of the three terminal regulator ICs on the old version. This has led to a considerable improvement in the dynamic performance and lower noise. The basic signal path circuitry remains the same as before. The pcbs have been made 100mm wide so that they will slide into the pcb mounting slots of eurocard cases. A big thanks to biovizier for pushing this project forwards and for all of his suggestions that are included in the final design. I'll leave him to tell you how much better it sounds.

There is a new version of the cascode power supply, the super cascode, although the classic cascode version will remain available. The super cascode still has the discrete rectifier bridge and smoothing capacitor on board and still uses an LM317 as a tracking preregulator, but the main regulator is now a discrete component design. The main regulator is a version of the Kaneda ( 1977 ) type design of the kind recently repopularised by Jung and ALW. My version offers a few enhancements over the latest Jung/ALW versions leading to lower noise and better ripple rejection. Compared to the classic cascode the super cascode offers much lower noise, much better line rejection, much better ripple rejection, much lower output impedance, and much better dynamic performance. Most of these parameters are so good that they are difficult to measure. The super cascode has sense lines and a star earth. The pcb is also 100mm wide for ease of mounting in eurocard cases.