Friday, June 29, 2007

Does size really matter?

I have gone thru the quest on paper to look for a small enough speaker cabinet to be used as a bass or sub-woofer unit some time ago. This has shown that besides the driver characteristic, the only way to get it to go lower is to increase the box size. There is a limit of course.

When I first saw the above box with the Fostex FE207ER-S at Robert's place, I was not expecting it to sound any way decent at all. Thereafter, I just continued to look at other stuff, such as the DAC that he has been experimenting with... he was telling me about the different low noise power supplies that he tried in various positions, which sounded nice at which part, etc... Then he started playing music thru those small boxes above the horn loaded speaker.

To my surprise, the mid bass is there! Based on memory, I did not think that it went lower that those horn loaded Fostex, but the horn loaded boxes are a multitude larger. Even though I had a flu which caused my hearing not to be what it normally is, but no doubt, it is still acceptable frequencies available from that small box (think small bookshelves, but with more bass). I cannot help but wonder why I'd want to have a low WAF speaker... should just get a small box with a sub instead.

I also wondered if the same box will work for my Coral Beta 8 driver... Please do not tell my wife about this pair of gem that I have squirreled away... But I am sure it will get the stamp of approval from her in such a small cabiinet. Maybe I should suggest to Robert to make it deeper so that it can accomodate the larger magnet of the Beta 8. ;)

Some pics here.

Thursday, June 28, 2007

mod done... and about time...

seems a long time since the last update... blame it on CommunicAsia 2007 plus the fact that my wife had to go on an overseas work trip to Europe for 2 weeks... leaving me to fetch Lucas and entertain him in the evenings and the weekends.

well... i did find some time on Sunday to finish up the output filter mod... but only on one channel. i reused 2 kiwame 30k resistors that i had together with some Blackgates that i got from my favourite DIY store... Ahfartaudio at Upper Cross Street. they have one of the lowest pricing around. i initially wanted 4.7uF BG NX, but he only had 1 left. someone else took out a bulk order for 1000 pieces or something like that... robert then suggested that i do an e-cap configuration with 10uF BG NX instead. since i have not tried this configuration before, i took up the offer... this places the cost of the caps at around the cost of the PS1... add in the PS1 remote controller that is on the way from ebay, future linear power supply mod and a casing, i think this project will breach SGD100++.

i did a quick sanity check with the PS1 to ensure that i did not screw it up. with a laura fygi cd on the PS1, connected to the TA2020 tripath amp and one speaker, i fiddled around with the controller and music was playing. don't ask for comments on sound... the speaker is crap, so anything coming out is crap. it has bass that is loose and not listenable...

doubt i will have time to test it out properly this weekend as my wife is bringing back a toy for me on Saturday. hee hee hee... might be too busy with this new toy. ;)

more pics here.

Wednesday, June 13, 2007

Sliding Bench...

A misnomer it must be.

Not sure if it is the need to be seen as embracing avant-garde designs or just trying hard to be stylish, but the metamorphosis of Dhoby Ghaut MRT brought about by Dhoby Xchange must have gone into the heads of those SMRT folks for them to justify buying those circa 26" metal benches that are placed close to the wall, with a slight tilt on the seat and a smooth finishing on the surface.

These seats are impossible to be sat on as it will cause you to slide forward and eventually fall off. Those who can master the legwork to keep from falling may well be giving their legs a much needed workout.

But i've observed with much amusement, people trying those benches, only to migrate off to the traditional marble top benches what is not just more comfortable, but stable and not as frustrating.

Maybe the only reason why they had this installed is to amuse the kids, as Lucas will demostrate in the below clip:

Give me a wall instead... and I'll gladly lean on it...

I think as far as sitting objects with amusement value is concerned, the head honchos at NLB have scored with flying distinctions with their Italian plastic chairs in the kids section at basement one, central lending library. These chairs can be sat into normally, and if turned on their front, it can be used as a rocking horse. But the customer service there is a fine example why we would never reach service levels like Japan.

Sunday, June 10, 2007

Modding the PS1

I spent some time to carry out the suggested modifications at Mick Feuerbacher's site. I did not have the correct capacitor value for the output stage replacement, but since the PS1 is stripped to the pcb, i took the time to perform the other mentioned mods such as removal of the dc blocking capacitors after the DAC, and also removal of the muting transistors. I also removed what looked like the mod chip. Initially I thought it was removed as I did not see the same implementation as shown here.

Looks like different shops mod the sets differently. ;)

Will get some small value blackgates for the output stage replacement... Not sure if I can listen to this next week as I am expecting to pick up some Zebrano veneer for my speakers.

Some pics here.

Saturday, June 9, 2007

A/B impressions of PS1

The anticipation of this moment since early this week... i pulled together my horses and men for this session. The other source is a Marantz CD50 using a TDA1541A dac. My 5687 preamp, d3A/VV302B DRD amps and my Diatone PM610MB speakers were called to duty.

Sequence of A/B is always PS1 first, followed by CD50 for each track.

Discs used are 1 - Plastic Flower from Op4, Lena Park (Korean Artist), 2 - The Power of Love Songs CD1, Fish Leong (Malaysian Artist), 3 - The Hong Kong Hifi show CD (2007 I think), 4 - You'll Hear Better Songs and Memphis Tennessee from Early Hours (Hybrid SACD), Eleanor Mcevoy.

Impressions are that the PS1 presents a lower output voltage to the preamp, the bass is rounder and not as profound, soundstage is less deep, and it has a more mellow presentation when compared to the CD50. It also seems veiled in comparision, with the CD50 giving a cleaner and clearer sound.

Perhaps after the mods, it will be better... I can only keep my fingers crossed.

Tuesday, June 5, 2007

Direct Reactance Drive

A long overdued post. You might have already seen the pics at my picassa albums.

This project actually started out in June/July 2004, and was my first attempt to build a tube based amplifier. On hind sight, it was a little ambitious to build a 300B mono block as a first tube project. Nonetheless, there are people who did it. Me, I only got it right on the second attempt.

Inspired by Sakuma san and Josh Stippich, I wanted to make use of those nice mercury rectifiers in my circuit. The RCA83 was bought locally at a rather high price. Netting these tubes on ebay would cost a fraction of what I paid.

I did lots of reading about tubes, and also got some online education of such stuff at DIY Audio. The Net is such a wonderful tool... I even attempted to create a DRD calculator in excel that helps calculate the resistor values and B+ required when certain inputs such as driver and power tube operating points are furnished. I was suggested to use the Siemens c3g as a driver for the 300B tube.

Suffice to say this this first pass project did not pass with flying colours. With a pair of inefficient (87db/m?) Totem 1 bookshelves, hum was evident even at 1.5m away.

I rebuilt this amplifier around Oct/Nov 2006. This was also partly due to reading the success of Luis Gascón with his DRD using d3A/300B on I built my version with d3A as the driver, but using LED biasing.

Testing this on my Mitsubishi Diatone PM610MB speakers (around 93 to 94 db efficiency), hum was only evident when my ears are around a feet away from the driver. All heaters are using AC for this build. Needless to say, I am very happy with my DRD amplifiers. ;)

More pics here.

Monday, June 4, 2007

Found... the elusive... PS1

Like they always say... Persistence pays off. This is quite true when I managed to find a Playstation 1 at a Cash Converters for SGD29 with 2 controllers, AV cable, one memory card and a power transformer for 240vac to 110vac.

This particular unit that I have is labelled a 100vac version. The store assistant asked if 100vac was ok. I immediately told him that I am ok. He then commented that I'm a confident customer... Actually I was thinking of building a PSU for the 7.6vdc and 3.6vdc that would be required by the unit.

When he brought the unit to the cashier, he also went to collect the accessories. It is in this bag that I spotted a transformer that seem to indicate 240vac. After paying, I went off to find a quite spot where I can inspect the bounty. And I was spot on. ;) It was indeed a step down transformer.

The moment I went back, I plugged in the AC and powered it up. The green LED was lighted. Hurray... I quickly did a test of the audio via the TV. Seemed that one channel is ok, but there was some hum. Perhaps due to wiring. Will do a real test soon.

Since the serial number or identifier sticker at the bottom of the unit is removed. My next instinct was to open the unit to determine if this was the real mccoy. I did not realize that the dac is actually quite small. I had to strain my eyes to verify the numbers on it. It was indeed the Ashahi Kasei Microsystems (AKM) AK4309AVM DAC 16 bit Stereo Delta Sigma chip. This mean the PS1 that I have is the SCPH100x version.

My next steps would be the output stage mod and the PSU mod as mentioned at Mick Feuerbacher's site. Let's take a real serious listen to how good this thing actually is. ;)

More pics here.

Sunday, June 3, 2007

The Last Sonic Frontier?

Probably the most neglected area in one's pusuit of audio enjoyment... and this would be sound treatment of the listening room.

The conundrum for me, then, is... how would you know what to use when planning for a new room? Especially when you have never heard your system in it before.

Well... perhaps a leap of faith and some reading. ;)

Initially I wanted to DIY something like the RPG Hemiffusor. There's a website that had the dimensions to do this. But I think this woud be a real time consuming affair...

The diffusor seen above was purchased as part of a mass order offered by joamonte on echoloft. I took me around one month before I finally pick up the 8 diffusors from him after he told me that they are ready. It was a late night affair when I made the pickup. I had the fortunate experience to listen to his system. It was really good. It is definitely showroom material... in fact, showrooms should take a leaf out of his book.

I might be adding some diffractal for the front, but now I am having problems with mounting 8 diffusor panels... not enough space in my odd shaped room. Perhaps I will go with 4 at the back and have a hanging ceiling for the other 4.

Rest of the pics here.

Outing at Lower Pierce Reservoir

After breakfast at one of the prata place opposite Teacher's Estate, we went to Lower Pierce Resevoir with Edna and her mum. Edna is Lucas' biting buddy in infant care. I think they express their liking for each other by biting... good thing the parents are cool about this. ;)

Now Edna and Lucas are at different child care centres. The only time that they meet is when we go out for such trips together. The last one was at Night Safari with Edna and her parents, and also Nathaniel and his mum, plus Lucas and us.

Some pics of the sunny trip here.