DIY CD Transport in a new casing..

It has been a while since I last post!

Had a few projects completed by not much time to update.

Acquired a Harman Kardon HD7225A that is not working anymore and suddenly remembered that my DIY CD Transport is badly needing a new case! Spent about 2 hours 'transplanting' the HK's innards with the DIY stuffs... Here's some of the work done:

 Top cover removed. Just a mainboard and transport mechanism. Hoping to use the existing transformer/power supply with the DIYed transport but...

 The transformer was 'built' into the mainboard with all the necessary rectifying circuits and regulation.. hmmm

 Transport mechanism removed! Several screws and quick disconnect cables..

 Front fascia removed too! Thought of using my own panel but later changed my mind. Too much work and I'd rather preserved the HK's look..

 Two major assenblies out of the casing, placed on the top cover.

 Top cover reinstalled to measure front fascia dimensions..
(This is before I change my mind..)

 The CDROM positioned to check for cd tray clearances..

 First power up, to check the new display from the CDROM controller.

 Whats inside. Just the CDROM, CD Controller and the 12V/5V power supply. This is temporary. Will install a linear PSU.

 Close up of the CDROM controller and the IDE cable connecting to the CDROM.

 Testing the transport, digital signal feeding the Behringer Ultramatch Pro DAC.

So far superb! Will finalise the work next weekend. ;)

5687.. status

After few hours of ‘burning in’ this is what I found.

The microphony of the tube is very tube dependent! I have bought two sets of the 5687 tubes by Tungsol and so far have experienced less ‘microphony’ in one than the other one!

Somehow AC heaters induces more hum, as such DC heating is more favourable.

I have stopped playing with it and waiting for the dual 50uF+50uF which was originally specified to arrived. There is this low AC humming which I suspect coming from the B+ voltage as I have used a substitute caps of 20uF instead of the 50uF originally specified. I was desperate and need to get it running before deciding to get the expensive stuffs or not. The dual cap was bought from ebay and could take anything form 7-14 days to arrive. Item was bought last week..

Till then..

PASS F5

Had the opportunity awhile back to audition the infamous F5, 25W+25W pure Class A power amp in my system. It's DIYed by a fellow forummer. I bought the PCBs.. wonder if I should build one.
Here the pix:

Verdict:
If you're looking for a kickass Class A 'heat' monster, this is it! For Class A purist only. Should be able to satisfy full range lovers. Unfortunately at higher than 'normal' listening levels, my RTL3 is gasping for more 'air'..the 'thirst' that only the Technics that I have can satisfy... 'nuff said.

The good news and some 'bad' news..

Okay, the good news is, I have completed the tube preamp, hurrah!!! That was about a a week ago.
It was worth the wait (and the agony of waiting)! The preamp was connected to a discrete 40 watter (nicked name,D'Bomb) and the sound is simply marvellous albeit some issue which is irritating me right now.

One, I have humming issues, then buzzing then 'crackling' issues.. After much googling and reading more about tube amp designs.. I managed to solve the buzzing by opting to use DC heater as opposed to AC heaters. BTW, I have read and done all the do's and don'ts about tube amps building thingy, like wires crossing at 90 degrees etc.
The humming and 'crackling' although very soft and only audible when I am not playing anything, it is just 'psychological annoying'... Since I used some 'alternate' (read cheap and what is avail.) parts to what was being specified in the original design, now that I have heard how good it is and believing that there is a potential for it to become 'better'), I think it's worthwhile to invest in quality/premium parts and I have decided to buy the 'good stuffs' online.. I also found the TUNGSOL 5687 is kinda 'microphony' and it is known for that! There are other drop in replacement for this 5687 but I would not do it till further listening. Since this is my first tube project, I just want to have some experience and maybe moving on to other popular tubes. More updates later..

The casing used (like a metal pizza box) was bought cheaply from a manufacturer excess stock meant for something else.. hehe

Pic shown the preamp during the 'wet-run'. Speakers used was the Gale 3030 floorstander and I could not believe the amount of good solid bass coming out!

A quickie- yes a short update

Its been awhile, I know. I have eventually received the last components about two weeks ago. They're the hard to find, 7 pin mini sockets! Now I actually have ALL the required parts including the casing for the preamp but whats holding me?
After looking at the project writeup and inputs from DIYers that had built the preamp, it looks like I have to use a good grade audio caps for the amp if I want it to perform.. it's gonna costs for sure but might as well do it right, right?
Hence I decided to hold it out a little bit longer till I acquire those parts...

5687 preamp progress...

Took deliveries of two major components:

 

The main power tranny.. specially ordered that took about 4 days.

  

One of the two 30H@100mA chokes that is required for the B+ supply. Took delivery about 2 days ago from my usual supplier..

The only thing I am short of now is the tube sockets, a 7 and 9 pin but a friend has a set and will get that soon from him.. Then I can start to build this long awaited project..

Cheers!

Cables,interconnects,plugs,sockets, do they make any difference?

This has been going on for ages! Some are a believer and spend a lot of 'mullahs' investing into the above tweaking and squeezing to get the last ounce/gram of 'perfection'.. I am not going to prove it or otherwise but of late I see no harm in  investing a few 'mullahs' just to see(hear) if there are differences.. I use differences here they may not amount to improvements at all! Any changes that satisfy my sonic needs will be classified as improvements..

I started awhile back by using/making my own speaker cables.. a really heavy gaged 14AWG conductor cables.. with a good high quality banana plugs I have compared with a commercial branded speaker cables.. I liked mine best!

I have made my own digital coax cables for my CD transport.. mini-to-mini cables for my headamp and headphones.. to name but a few.. but I want to draw your attention to my latest findings..


Based on some discussions in an audio thread in a local forum, I invested in a high quality MK 3-pin plug. The fuse is silver plated so are the fuse holders.. the wires in the plug are held by very solid binding posts!

I wasn't expecting much but the first half hour I begin to detect a very minor changes... microdynamics has 'improved' somewhat.. the low end is well rounded and the mid bass was really in focus! Midband/range is slightly projected and its kinda rough and edgy with a rough edge.. top end was some what well define but still within control.. as the minutes and hours ticked by, the rough edges has been trimmed somewhat.. I noticed the PRAT has somewhat picked up.. and I am not used to such a high speed.... I like my music slow and mellow..

Still in the mood of 'fine tuning', I took out the silver plated bussman fuse and replaced it with a 'no-name' fuse.. To my amazement, that has somewhat tamed the midband, polished and pushed back a little bit of the midband projection, still I am not satisfied... bear in mind, I am a bass head and liked my music relaxed.
The source of my music was my favourite CD: Sadao Watanabe- How's Everything. LIVE at Budokan. I have been listening to this album since 1980, and believe me I know every beat/note in every song! A SONY CD player was used feeding my DIY STK hybrid amp, powering my favourite speakers of all time, RTL3 made by TDL Electronics. A transmission line speakers that I am in love with and never looked back since!
Reviews here: RTL3 Review


I am going to give it a few hours to 'settle down' and may look into changing the 'normal' mains cable into something that was recommended in the threads..

Will update soon... Happy listening guys!