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-   -   Hifimediy T4 board (http://www.diyaudio.com/forums/class-d/187227-hifimediy-t4-board.html)

TheDealer 17th April 2011 11:48 AM

Hifimediy T4 board
 
Hi all,

just wanted to notify that I connected the T4 with a 450 Watt high quality torroidal. It worked fine with only a small issue that the green ready light went off and then 2 sec. later again on when I plugged the input socket. I think this is just a protection feature (better sensitive than no protection ;))

The second issue is still the very light but hearable ground hum when you get close to the woofers with your ears. This can depend on the cinch connections of the cd player.

The sound: after 40 minutes burn in it promises much for the future. Of course it could not reach the resolution of the battery powered and burnt in TA1021B but you can feel the power increase and I it should have the ability to beat the only 2 x 10 watt TA2021B one day.

All in all I am pleased with the result for now ...

If there are other hifimediy T4 builders please let us discuss here regarding tune ups or general listening impressions of this board. The standard hifimediy thread includes too much different boards meanwhile.

Centvrion 23rd April 2011 06:14 PM

Hi TheDealer
I'm listening to my new T4 amp, finished three days ago.
It's UNBELIEVABLE ASTONISHING!! It has a full control on the whole gamma, a solid detailed and very 3dimensional sound!
I experienced the same sensation in the first 40mins , but after about 20h I can say it's stabilized.
About the hum, I can listen some only when the amp has just been turned on, turning the pot to full power, staying about 40cm near the speaker, in a quite room. After 10 minutes of warm-up I have to be in the same situation, but with my ear at least at 10 cm to listen the hum...note that I use pseudo shielded (neutrum connected to shield only at source side) twisted wires interconnect(signal) cable (Bedea made in Germany 1,5mx2 microfonic cable, paid 12€ with RCA gold plated plugs) between my soundcard (an old but good creative extigy) and the T4. Inside the amp I used a particular cable (about3,15€/m, not so expensive), low impedance very good shielded, but here inside, shield is connected to real ground. I made up a support for the pot which also acts like a shield for the pot and what in italian is said "centro stella=star center" a piece of iron where all ground cables are connected. Power and PSU (meanwell s-350-48) cables are twisted. Amp box is made of MDF (wood), front panel in stainless steel (the only one I could find, even if I would have preferred aluminium). With this configuration hum is very very low, especially considering the high gain T4 has.

Now I have some questions:
Did you leave the leds on the T4 board or you put them on the front panel? I was wondering what/how to do...
Did you put a cooling fan in the box? The Meanwell is ice cold, but T4 it's a bit warm ( I can leave my hand on the heat sink about 20s or more...uhm... I don't know...probably it's useless, but I don't know the real chip temperature and its limit and I thought it's safer put a 8cm diameter 12V (computer fan) "undercharged" (6,5V, very quite). But probably I will remove it.

For now I've built up my audio system for less than 250€ and it sounds toooooooo good!


GREAT T4!

Centvrion 23rd April 2011 07:01 PM

Sorry, I forgot a piece:
Quote:

Originally Posted by TheDealer (Post 2541289)
[...] It worked fine with only a small issue that the green ready light went off and then 2 sec. later again on when I plugged the input socket. I think this is just a protection feature (better sensitive than no protection ;))[...]

I think it's a safety protection! I experienced the same situation when I suddenly put of the power cable from the sound card: it produced a loud clack, but suddenly relays opened (so green led went off), to protect speakers ( and maybe electronics too).

Good Easter day :-)

TheDealer 23rd April 2011 08:13 PM

Hi Centvrion,
Itīs fine that you nearly found your matching amp for your tastes. Which speakers you use ?

First I must clear some differences between yours and mine build up of the T4:
1) I use a 450 VA high quality torroidal because I found the sound of another Tripath with TA3020 supplied by a torroidal damn good. That was the reason not use a SMPS. But on the other hand I am still supplying my T2 with a good japanese SMPS and the result is amazing.
2) I did not put the system in a case yet. So I cannot say how to integrate the lights. But It should be an easy thing to cut the LEDs and draw them soldered to a front panel.
3) We have different systems as source. My output regulated Pioneer CD Player was directly connected and this CD Player could also be a reason for the ground hum through itīs cinch sockets.
You can listen much louder ground hum when you touch the cinch sockets and move them lightly. My silent T2 is connected to a Marantz CD Player because the T2 has the Vol. Pot. on the board ready mounted. I have to play with other sources to say more about eventually changes in noises.

For your temperature issue: I would not experiment with other cooling systems. Try to stay in the midle of DC supply range - not the maximum. This board has enough power to loose a bit supply gain. Donīt know if the Meanwellīs output power could be adjusted to minimum.


Further feedbacks I will deliver here after results. I also wish you good times with your T4 ...

Centvrion 23rd April 2011 09:56 PM

Probably my full shielded implementation is a bit too much...in fact your problem may be your CD player source.
I'm already using T4 at 40V (I left the PSU as it was when arrived), and I don't need more gain because it's already sufficient for me; I don't ask anything better than this (at the moment, at least)!

I'm using a pair of modified "transflex"(search them on the web, very interesting 1952 subwoofer project)...! It's a prototype I tried to build because my uncle had to get away some good 27mm(!!) hardboard/chipboard huge panels, and I wanted to give new life to a pair of little 6,5" subwoofers from creative HT sys and a pair of coaxial 5" car speakers... woofers are quite good (value around 25€...could be?), but car speakers has a quite harsh treble (I solved this in part putting on the tweeter a piece of a sort of synthetic foam-wool -the one used in cooking air-filtering system...I don't know how to explain...- this method is as efficient as odd XD).
Cabinet is a once folded pure quarter wave resonant tube, tuned at 40Hz (they are 1.10-1.15m high), with woofer placed between the beginning and the end of the tube (a sort of push-pull) and the coaxial placed at the 2/3 of the tube lenght, between the outside and the last part of tube(I have some designs but on the other pc). But there was a pair of problem: speakers are 4ohm and I wanted 8 for T4 (even if, as you know, it woks well at 4ohm), and I did not have speakers parameters, money and time to build a proper crossover; I partially solved this connecting woofer and coaxial in series, but this caused a filtering: less treble and a bit accentuated mid; at the end I solved also this problem with a good music player (on ubuntu, "audacious") equalizing a bit (max 2/12). As a result I have a pair of full range T-line 20Kg speakers for less than 80€ with a really quick, very clean and extended bass (near 33-34Hz), a detailed treble (not so "kind" but I like so) and a quite good mid (I non-directly compared and will directly compare them with a pair of more than 1000€ Tannoy monitors: comparable, even if Tannoy cost more than 10 times...ghgh)...
I wanted to tell you this experiment because it gives really interesting results...:); I don't know if I will substitute coaxials speakers with a good couple of mid-woofer and silk dome tweeter plus a crossover...at the moment I have 0s time...ghgh:eek:

TheDealer 24th April 2011 12:30 PM

Building DIY speakers can really make fun and you can save money at same time.
But speakers construction is a complex theme. Thatīs why I tend to invest in used speakers from popular manufacturers. Calculating price for new chassis and your working time, a DIY projekt could be more expensive and does not sound better.

But if you are happy with the result of your projekt, what you want more ... ?

Centvrion 24th April 2011 01:05 PM

Quote:

Originally Posted by TheDealer (Post 2549257)
Building DIY speakers can really make fun and you can save money at same time.
But speakers construction is a complex theme. Thatīs why I tend to invest in used speakers from popular manufacturers. Calculating price for new chassis and your working time, a DIY projekt could be more expensive and does not sound better.

But if you are happy with the result of your projekt, what you want more ... ?

I really agree with you, and not only about speakers or audio stuff!
But in my case I had already material and this kind of box doesn't need to know speakers parameters (this fact was proved by what I can listen now)...
After all now I have my system and I'm happy with it!

Has anyone else built T4?? Can someone compare it with some Mark Levinson, Krell, McIntosh, NAD or other famous amps?

kristleifur 24th April 2011 02:36 PM

Quote:

Originally Posted by Centvrion (Post 2549270)
Has anyone else built T4?? Can someone compare it with some Mark Levinson, Krell, McIntosh, NAD or other famous amps?

I can believe that this amp is awesome! I love love love the 41Hz Amp4, which is pretty similar (same chipset). The Amp4 is again similar to the TA3020-based 41Hz Truepath - which has indeed been compared to some famous names:

Clash of some Titans - Page 3

See post #24 and down.

TheDealer 24th April 2011 06:17 PM

I am quoting V-Bro in post #24
Quote:

and compare the subjective differences between a Mark Levinson, a Briston, a Nelson Pass and my Truepath amp
In fact this must have been a Briston (from China ??) and not a Bryston:):D
But I can imagine that these had really problems to match a well conctructed Truepath. Excellent workmanship from V-Bro ... hands up

cOz 27th April 2011 03:51 PM

Forgetting about cost, I wonder how T4 would compare to TruePath. I am going to build one of the two but am not sure which way to go. My trafo puts out 40v and the makers of T4 say that is ok, but I still am uncertain.


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