An interesting couple of days. These boards are are put together with spit and warm wind. You can mod them once if your lucky, going in for a second or third time is really chancing your arm. 4.7uf for the input gave too much bass, despite the caps being far superior to anything else I had. 2.2 ICW polyprops (dubious heritage having been in and out of other stuff) resulted in the signal dropping out (nothing to do with poor continuity on the board). Lastly some 2.2uf Wimas (275v) went in and bingo! sound very nice, although bass is still a little full. I have Tripath TA2024, 2020 amps 2 IRS2092 amps (one dual mono 50wpc, one stereo 125wpc and this sounds really good in comparison.
Wimas are good. I doubt the amp is passing too much bass, that size cap is probably allowing it to be flat down to a very low frequency.
Work on supports and vibration control and the bass should tighten up considerably.
Your response made me smile regarding bass control. You will probably not remember but I (think) I documented my journey with a pair of EAR Primary Drive OB's that were gifted to me. They were said to be a prototype of the design although looked to all intents and purposes like the finished article. The bass unit has it's cone surround removed and the cone is bonded to a planar panel that is attached to the OB frame. The panel was originally fixed at the 4 corners presumably allowing it to flex. I think this is called Correx sheet which is pretty stiff and doesn't flex but vibrates I suppose. It took me about a year on and off to firstly centre one of the bass units as it was rubbing and to stop any buzzing caused by the unruly panels. I cut loads of small wedges and inserted these around the correx panel and it was a matter of trial and error as to whether they were in the right place and if they were doing what I wanted them to do.
I got to the point where I thought that they were good enough and left it like that. I have ideas as to how I could tame them hopefully once and for all but on 99% of the music played they behave themselves. I have made Fostex Back Loaded Horns (Lowther PM6c's fitted as well) Lampizator OB's used many commercial infinite baffle and reflex speakers, but these seem to do a lot of what I like to hear very well. They can however be a bit bass full and moving them about only gets me to the point where I am not sure where they sound best!
The track that had me up and down yesterday like a jumping bean was Jennifer Warnes - Way Down Deep from The Hunter. If you know this track then you will know that the bass drum (or is it a Surdo or Tar or something) is cleary at the wrong frequency for my speakers.....now who do I complain to about it
Sorry for jumping in at the end, just joined sooo, anyway the whole class D thing is very interesting, i actually work in the pro audio sector and class D is pretty much 100% all we install as far as amps are concerned, brands like Crown, Apart and Extron tend to be the ones we use most, for pro installs they are hard to beat, they tend to be much smaller lighter and run way cooler than other classes so perfect for rack mounting into a cabinet where heat is always on the high side, on top of that they are mega efficient and can kick out masses of power.
Would i use one in my setup? probably not or if i did it would only be to power a sub or a set of low frequency units in a pair of open baffles running dual amp, the reason for this which has already been said is they lack in the finer elements that makes an amp great and gives the music that sparkle, so for power hungry bass they tick all the boxes but for mid and HF they lack the finesse of a good valve amp or class A or B even.
^ I've owned a lot of class D, and pretty much without exception the higher power class D amps do indeed "lack in the finer elements that makes an amp great and gives the music that sparkle" as Mike jachawk put it. The recently departed Primare A34.2 power amp (200wpc) was another one of those.
Some of the lower power class D "T-amps" certainly do have that sparkle (e.g. those with the TA2020 chip) but are limited to about 10wpc and so lack the oomph that many setups require. Based on my fairly extensive experience it seems that you can't have your cake and eat it as far as class D is concerned.
I had some £30K class D Rowland 301 monos driving my first pair of Apogee Duettas at a bake off. Not too bad but not overly impressed especially considering the price. Those same amps where better driving Wilsons.
Had some Hypex 700 Merrill monos at £12K driving my second pair of Apogees. Bloody dreadful. Just dire. Hated them.
Actually Jerry's Crown 1500 (can't remember the prefix letters) was better than the Merrills at about £150 odd. Still while OK value the Crown wasn't great either.
Heard loads at shows etc.
Best so far was Hypex 400 modules fed with a linear power supply made by the chap who built my Apogees.
Indeed the smaller 85w version just delivers music, exactly the same one that Jules listen to and wasn't to keen on.
Speaker amplifier impedance is critical with any class of amplifier. switching amplifiers done correct are a match for any other amplifier class however because of the stigma of having some of the older designs were not up to scratch in the same way cd players were pretty naff untill 1996 counts against them audiophiles get hung up on single ended strides and class 'A' warmth
I am very fortunate to be a able to pretty much acquire any of the desirable amps made if i wished yet I only listen to pwm switching amps. Some of amplifiers I could use daily are Audio note Gakuons or M600 moons. Both superb musical amplifiers yet I am uttedly convinced of switching amps I could run through the specs but you just need to listen. Recently I have had the privilege of spending time with some quite special equipment and it was rather good indeed, however it did not cause me to feel I need to acquire this application combination right now or wow I need to recalibrate my listening experience.
If you have tricky load speakers then 110 amps if current swiching in 20 nanosecond with zero grain makes even Magicos Q7's sound listenable well almost!
Correctly engineered they produce some of the natural unforced musical engaging sounds currently possible yet so many do not deliver this. A few of the older tripath modules could be made to sound very listenable by the DIY community. Examples of which I feel really do no favours to club Devialet, hypex modules and some though not all of the B&O modules. They have progessed a long way from the first insertion onto the markets but due to the audiophool rank and file stubboness to embrace the technology and hang on to halcyon salad days then only those that appreciate pure natural articulate unfussed grain sounds will use them daily. They are not a golden ticket to audio nirvana but can deliver some wonderful musical sounds
Hi pukka2go, That's a nice panoramic vision about the classD in the audiophile context, and to me very realistic. As a diyer, I would like very much if you could give us an example of a great tripath board, for us to make a musical amplifier that would have a reasonable cost and would not make us feel frustated, because the memory of good old school analogic amps in our minds make us ceptical and not satisfied when we ear classDs. Something that at least could be on pair with good classical middle range analogue amplifiers. I will buy that board. Thanks!