Was wondering if any one can help with how to contact... http://electronics.dantimax.dk/
I have placed a order for three remote boards and three motorized alps pots.
all of the contact links do not go through that is supplied on his sights. Hopefully someone has a email address or contact information that has worked for them and can share it.
Posted 25th February 2015 at 01:24 PM byrjm Updated 26th February 2015 at 12:41 AM byrjm
Ok, so why donít you like the K702s?
I didnít say I didnít like them. Just that I think the HD600s are better.
Itís pretty simple really:
The K702s have a strident, hard upper-midrange "bump" that I find disagreeable. Yes, it makes tracks sound more ďliveĒ, but itís also fatiguing and a bit clinical, and - as many others before have noted - makes the sound overall somewhat thin. In direct comparison the HD600s seem full the point of boominess, but I'm willing to accept that midbass plumpness for the Sennheiser's warmer, luxurious midrange. In imaging, the K702s trend to a wide, distant, airy soundstage while the HD600s run towards a closed in, intimate presentation. In that sense the K702 are more like listening to speakers, and I can certainly see people being attracted to that.
These are both top-shelf headphones at the top of their game, I don't mean to imply that the AKGs are bad. The two...
Posted 22nd February 2015 at 02:24 AM byrjm Updated 28th February 2015 at 07:17 AM byrjm
I've added an additional RC filter stage (R3, C4 in the schematic below) before the Zener diode, substantially reducing the amount or ripple on the transistor base by cleaning up the voltage applied to the Zener reference. (The original Z-reg is described here.)
Circuit shows C2 with a value of 300 uF. Typically much larger values are used. I kept the filter capacitance to a minimum here to show circuit working with a reasonably high ripple (1 V p-p) on the input. The rectifier diodes used here are of no particular consequence, I just wanted the simulation to generate a realistic sawtooth for the input.
OK, this doesn't do as much as I originally thought. The improvement is mostly below 100 Hz, whereas the ripple is mostly in the 100Hz-1kHz band. There's perhaps 3 dB less output ripple, but that's about it. You can verify this yourself in LTSpice, just cut the wire between C4 and the junction or R1-R3 and rerun the sim.
Posted 17th February 2015 at 10:02 PM byJeffs Updated 17th February 2015 at 10:10 PM byJeffs
This all got rolling after checking CL then picking up some 30+ year old 4 ohm speakers I had wanted since I could drive to a store and drool. Sure, might rather have some old Polk SDA's like the ones briefly owned in 1989, but am happy with what I got and the price.
I started reading DIY Audio a few years ago, and a couple of years ago was sure I was going to build one of the F5 Turbo variations one day. After disappearing for a few hundred hours to read all of the treads I was confused and it was time to buy a new roof, and spend a couple of months in India... so had to quickly forget about the idea.
I should have done an Amp Camp project to learn more about what does what.
This morning I ordered JFET's and MOSFET's from Alex (Alweit), has an eBay store and is a member on the forums.
I picked up the F4 boards from the DIYAudio store a few months ago, probably after Jim (6L6 on the boards) initially read about my ideas of...
Posted 16th February 2015 at 12:50 AM byabraxalito Updated 16th February 2015 at 02:34 AM byabraxalito(Red Wine it isn't, just the same designer)
Here's something very misleading in the 6moons preview of Vinni Rossi's (of Red Wine Audio fame) latest supercapacitor powered kit. They have 18 * 350F supercaps in the box and they say '...the total rating becomes a whopping 6300F'. However each capacitor is only 2.7V so presumably to get any audio signal at all out, they need to operate these caps in series. Caps in series don't multiply, they divide so the total capacitance drops by a factor of 18. Hence only 19.4F. Not a small difference from 6300F or did I miss something?
I think I may have missed something - they aren't using all the supercaps all the time, rather there are 9 discharging and 9 charging. So the total capacitance in the audio circuit at any time is 350/9 = 39F. Still an impressive amount of capacitance but the problem is that the ESRs add too. Here's the datasheet for the Maxwell 350F ultracap they appear to be using - http://www.tecategroup.com/capacitor.../BC_series.pdf...
Posted 14th February 2015 at 12:47 PM byrjm Updated 1st March 2015 at 01:26 AM byrjm
Rhymes with "custard"...
Each channel has a BB OPA134PA - socketed - for voltage amplification and an eight transistor discrete buffer with 2 ea. 2SA1837. 2SC4793, C546B, C556B. Dual mono layout (more or less ... the circuit board itself is shared and not completely symmetric).
There's a pair of NE5532s at back for balanced-unbalanced input conversion, and a pair of transistors (TIP122 TIP127) with trim pots and circuitry between the input and the main amplifier which looks a bit like voltage regulators to me but I can't see where they fit in to the scheme of things.
Pretty decent quality for the price. (I paid $350/delivered)
First impressions of the sound are quite positive, plenty of depth and decent smoothness. Letting it cook overnight now and will put it in the main system tomorrow.
Comparison notes vs. Sapphire (with Sennheiser HD600s)
Posted 13th February 2015 at 05:16 PM bywlowes Updated Yesterday at 12:34 AM bywlowes(Tube amplifier tuning - manginin resistors)
As with other projects, I like to start with the disclaimer that this entry is just a scrap book of my personal journey with a build. No fresh engineering here, so those seeking engineering insights can save the read.
That said, I now have a week of burn in on my new music server, and for me its a delight. It is a collage of ideas developed by diyaudio members and by Lukas Fikus, aka Lampizator.
I still need to do some debugging, and create an aluminum top plate. There will be holes in the plate allowing the Tubes, RCA outlets and power cord to rise vertically out of the box. I have a home built AVC volume control in matching American Walnut which sits on top. The interconnects are a short path to the AVC and then to OLT mono blocks. Attached are some pics from the top and bottom sides as my layout is a 2 story affair.
My approach is heavily influenced by Lukas of Lampizator fame. I have enjoyed his tube output amp...
I bought these speakers in 2000. I was unhappy with the way they reproduce low frequencies. I decided to add a subwoofer. I used the fact that the lower part of the housing of the speaker is empty and isolated from the upper part in which the speakers operate. I cut a hole in the side of the bottom part and installed a 25 cm driver.
It is Vestra PW-250-2154 woofer.It has a 19 cm coated-paper membrane, foam external suspension, extruded metal sheet basket, ventilated 4.5 cm coil, the diameter of the magnet is 12 cm, 80 W, 4 ohms, the self-resonance (Fs) at 27 Hz.
I damped the interior of this newly created enclosure space with bitumen mat and felt glued to the walls and filled it with fleece. I cut out the rear wall from the top part of the enclosure. Inserted a reinforcing crossbars into the lower and upper housing. The upper part of the housing is entirely filled with a damping material (with fleece filled pillow, which...
All measurements done with Panasonic WM-61A microphone with Eric Wallin preamplifier and E-MU0202. Single driver frequency response without any crossover. The microphone is located at a distance of 1 meter from the driver on its main axis.
Vifa 3075 dome tweeter:
Vifa TC 3520 woofer:
Vestra PW-250-2154 woofer with it's crossover, microphone located 10 cm from the driver:
The complete speaker after modification.
Measurements done at my usual listening spot, 2.5 m from the speaker, microphone positioned 50 cm closer, farther, higher and lower around the spot. Obtained frequency response curves are strongly smoothed, because changing the position of the microphone produces a large change in the jags of the curve, and I wanted to show invariant features of the speaker frequency response:
It is pretty flat, and the bass is very nice now....