1] I hold opc's "The Wire" series of headphone and power amps in high regard. Small form factor, simple no nonsense designs and killer performance. God bless that man
I'm fortunate enough to have a few pieces at home. Primary, is the SE-SE headphone amp that gets used for both music and late night movies... Also, under construction is the A/B Power Amp, utilising two 55V/45V DPS-600 smps. This should provide over 100 Watt per channel into 8 Ohm load. Nice, but way to powerful for my spare little room.
opc designed a Low Power Ultra High Performance [LPUHP] Amp giving 16 Watt into 8 Ohm @ 1% THD. This was based upon the headphone amps he'd designed, using the same LME49990 opamp, but paralleled 8 LME49600 buffers.
Unfortunately I didn't have the funds to get both the A/B Power Amp and LPUHP Amp. Plumping for the former...
My little spare room is just that... Its 3m[w] x 2.9m[L] x 2.4m[H] and is full of...
So upon seeing many nice Blanda bowl projects here on DIYAudio I thought it about time I had a try and see what all the fuss is about!
About a year or so past I went through a phase of buying the nicest small wide-band drivers I could. Whether I achieved this is subject to the readers' opinion
So I have a pair of Mark Audio Alpair 5, and a pair of Tangband W3-1285SG. Both of these drivers were available to me in the UK at a very similar price-point and they both fall roughly into the 3" wide-band category. (Shown in the following picture alongside some Tangband 2" drivers)
I chose to buy the 20cm Blanda bowls in bamboo. Gross volume works out at ~2 litres. Factor in stuffing or denser absorbent and I guesstimate a 1 litre volume.
This is really too small for the Alpairs, but the 2 dB rise towards the cut-off wasn't...
Posted 4th April 2013 at 02:58 PM bymarkusA Updated 4th April 2013 at 03:53 PM bymarkusA
Some more information about my baby.
- Walls 18mm Birch Plywood
- Baffle 36 mm Birch Plywood
- Internal corner braces
- Cabinet edges rounded r=50mm
- Shelf bracing 12mm Plywood, large holes for least flow resistance.
- Ports r=35mm
- Port flare r=15mm
- Fiberglass insulation on shelves, top and bottom
- Polyfill light stuffing only.
Let's consider this a whishlist and a work in progress. Untill I start cutting, everything is subject to change if I find a better solution.
The construction is always the most important part, no single part will ever come close by itself.
The k.i.s.s. principle is handy tool and Einstein had it right. Everything should be made as simple as possible, but not simpler. D.S.
Posted 2nd April 2013 at 02:46 AM byrjm Updated 4th May 2013 at 11:54 PM byrjm
It came up at the help desk, but I want to put this before diyaudio.com members generally:
I feel strongly that people who build audio equipment as a hobby should take it upon themselves to obtain a basic understanding of both the practical and theoretical aspects of electronics. Take a trip to the library and read through the first couple of chapters of electronics textbooks, that kind of thing.
It's more than just the safety aspect, I think of it as a basic necessity...
So, how many people here are familiar with the following statement?
If you don't think about it too hard, you'd imagine that the signals in the phono stage would be smaller than the signals in the line level preamplifier stage that follows it. Or that the signals in the DAC/CD player would be about the same level or slightly lower than the signal in the preamplifier.
As usual, the answer is "it depends". It depends on the sensitivity of your speakers, how loud you are listening, and the voltage gain of the amplifier. It also depends on whether we are talking about a MM phono stage or low output MC.
My point is simply this: the volume control is an attenuator, and at the typical "9 o'clock" position the input signal is reduced in magnitude by about 35 dB.
That cuts it back down to being comparable to the output of a moving magnet cart, and much, much smaller than anything found in a DAC stage.
It means you absolutely, definitely, positively must spend as much effort and care...
A few quick notes on using a tuner for digital audio clock jitter analysis (before I forget the details). Someone here (I have forgotten who) suggested an FM tuner for monitoring jitter. After a little research and experimentation I went pretty deep into figuring this out.
First the internal clocks on ADC's and DAC's have strong harmonics into the FM band. Second, FM tuners are very sensitive to modulation to carriers. modulation and jitter are closely related. The other advantage of this is that the jitter/phase noise is multiplied by the ratio of the actual carrier and the harmonic you are looking at. E.g. a 22.5792 MHz clock becomes 90.3168 MHz with the noise amplified by a factor of 4.
This is very simplified but covers the essentials-You need a really low noise FM tuner. Sound good is not an issue. The Yamaha TX-930 and TX-950 are possibly the lowest noise tuners ever made. They can be had for around $100 on eBay. What I did was to take the output directly...