New TK2050 board

[kristleifur]

hi
im using hawthrone open baffle speakers that are re-inforced with augie(subs) bass drivers,there very high sensitivity drivers(the main drivers).
Hawthorne Audio Silver Iris (15 inch coaxial OB driver) review - [English]
im using these with audionote valve pre and power amps,the plate amp used to power the bass re-inforcement.
ive been running the tk2050 for afew days,i was hoping to set it up exactly the same as my above system but as you know i can not now do this due to the plate amp issue so at present im running the plate amp via my pre outs.
at first i found the tk2020 amp very smooth,wide soundstage but very flat depth,i also found the treble recessed and the little details in the music that make things seem more real just wasnt there.
of course this is just my opinion and to my ears and in my system,also bare in mind that its only been running for afew days just incase theres a break in effect.
all the above isnt ment to be a negative remark,its just how im hearing it,the amp is a bargan and certainly impressive in its own right and could certainly shock afair few people with its sound quality alone,throw in how much these cost including the power surply and your on to a winner
i was hoping to get alittle nearer to the sound of my power amps(then again valves just do somethings others cant),the valve preamp adds a nice effect to the tk2050 which suits me,ive also hard wired and replaced the input cable with some better quality cable which has certainly opened up the sound,ive also replaced the caps with obligetto types which has done wonders for the top end...so its all work in progress still.
would love to get rid of the on board volume pot but i take it thats not such a simple thing to do,as at present its running through two volume pots
the trouble is when the on board volume pot is turned to max i get hum/noise through the speakers,i dont know if this is due to the amp or something else related in my system,so i may not be able to ditch the volume because of this if i can not sort it.
hope this has given a little insight.from my prospective at least.
all the best
smithie

Thanks, yes, that's really interesting. I'm looking forward to the day when I have a little bit more cash and can do experiments like these myself - until then, I'm there by proxy

Regarding the pot, I think removing it shouldn't be too difficult. I don't know exactly how those boards operate, but I think you could just use wire cutters to cut the pot off the board, and then make a solder-bridge or wire+solder-bridge over the correct pairs of pins – the pin coming from the input is taken and wired directly to the pin going to the amp input; The third pin will be ground, and left unconnected here. That's one channel - the other channel is exactly the same. It should be quite easy to see what pin is what simply by looking the board, perhaps after the pot is off. If that fails, a continuity beeper meter will do the trick. Pots are so very simple devices. If you look at the board with this context in mind, I think you'll see how it all fits together.

Here's a really clear video explanation of pots and how they fit in the picture: How a Potentiometer Works

 

[smithie]

hi
sometimes when you dont have alot of money to throw in this game the better results you obtain as you tend to experiment more,of course its always nice to have plenty of money,those days are over for me,i dare not think how much money ive spent on this over the 30 years ive been playing with it
thanks for the info and link regarding the volume pot,as you say its easy enough to sort out,ive done plenty in the past,its just that i read somewhere on this thread that there was a dc element being shunted back to the inputs if the volume pot was taken off,as i dont really understand the workings to well of this amp i was just treading careful,anyway until i sort the nise issue out theres no point me doing this yet,saying that i have a nice steeped attenuator with dale resistors thats just begging to be given a test drive
all the best
smithie

 

[kristleifur]

thanks for the info and link regarding the volume pot,as you say its easy enough to sort out,ive done plenty in the past,its just that i read somewhere on this thread that there was a dc element being shunted back to the inputs if the volume pot was taken off,as i dont really understand the workings to well of this amp i was just treading careful,anyway until i sort the nise issue out theres no point me doing this yet,saying that i have a nice steeped attenuator with dale resistors thats just begging to be given a test drive

Ah yes, I see – I'm pretty sure that the circuit is like this:
[amp inputs] >> [volume pot] >> [input capactor / dc blocking] >> [amp input pins with DC]
The input cap blocks the DC from the pot, so the pot doesn't have voltage offset over it. That's how I've always assembled my 41Hz amps, and I don't know that there is another way to do it. Hence, the pot can be removed.

I believe that the issue is that when you're ADDING a pot to these amps, you can't do it between the input cap and the amp input pin itself. But a correctly placed pot in the first place, this can always be jumpered.

 

[smithie]

once again kristleifur thanks for the info and wisdom
i shall certainly be tring this at some point.
all the best
smithie

 

[kristleifur]

 

[alkasar]

Ah yes, I see – I'm pretty sure that the circuit is like this:
[amp inputs] >> [volume pot] >> [input capactor / dc blocking] >> [amp input pins with DC]
The input cap blocks the DC from the pot, so the pot doesn't have voltage offset over it. That's how I've always assembled my 41Hz amps, and I don't know that there is another way to do it. Hence, the pot can be removed.

I believe that the issue is that when you're ADDING a pot to these amps, you can't do it between the input cap and the amp input pin itself. But a correctly placed pot in the first place, this can always be jumpered.

indeed, this is how the volume pot & input caps are placed in this board.

The comment read above by smithie was in case someone wants to bypass the amp input caps, because the source has output caps for example. The comment was about the pot exposure to DC then. Another look at the same issue

BTW, do you know why it is not recomended to expose a pot to DC ? i read it has to do with noise, but never found a clear explanation where this noise comes from ?

 

[kristleifur]

BTW, do you know why it is not recomended to expose a pot to DC ? i read it has to do with noise, but never found a clear explanation where this noise comes from ?

I think rather it's because then you're connecting that voltage offset to ground via the pot, and that's bad for the chip. Or that's how I understand it at least. IOW, the sanctity of the voltage bias is violated.

 

[sendler]

Hum

ive also replaced the caps with obligetto types which has done wonders for the top end...so its all work in progress still. the trouble is when the on board volume pot is turned to max i get hum/noise through the speakers

Did you wire the new caps from/ to the same pins as the original input caps? If you put them in line with the new input wiring and jump the old caps you will have let the amp's dc short through the pot though I have read other reports of stock amps causing a hum with the pot full on. If you remove the pot you can experiment with adding a 10k-100k resistor to ground to give your source and cables some termination.
.
If you want to unleash the transparency in the highs, you can try some different caps in the output filter, un-wind/ re-wind the coils down to 4.7uH according to a calculator, or replace them with my favorite, Wurth XXL at 4.7uH. With these Tripath amps, the coil is the key.
.
I think he is using the T68 type 2 cores? Measure the diameter to find out what size they are.
T68-2
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Digi-Key - 732-1239-1-ND (Manufacturer - 7447709004)
Too bad they are getting rare. Wurth and others make a million different models of coils that all look about the same but the XXL is an older design and still sounds the best.
.
http://www.diyaudio.com/forums/class-d/162765-coil-pile.html
.

 

[smithie]

hi
i just replaced the caps via there usual mounting postions on the board,the new input leads where soldered onto the board joints where the plug socket connects so i shouldnt have screwed anything up regarding introducing noise back into the board( other then the new caps are standing slightly off the board due to there size).
since i ordered two boards ive plugged in the fresh one to see how that fairs regarding noise when the volume is turned up, i can confirm this is the same,so its nothing ive done.
im not going to be quick to blame the boards for this noise,could well be something else in my system,hopefully ill get a chance to play at the weekend and see if this is the case,of course if it does turn out to be the boards then this will certainly be abit of a issue as i want to get rid of at least one volume pot,maybe the resistor idea could be a solution has i have way to much power for my needs and can afford to attenuate alittle volume,although having resistors in the signal path isnt idea it would be the less of two evils
to do this i assume when taking out the pot instead of running wire to bridge the missing pot i would stick in some certain value resistor on each channel? or would i have to go with a l-pad type approach to ground? any idea what ball park starting point i would need to set the board at half power output,that should keep the noise issue well out the way.
sendler...intrsting views regarding the output coils,would love to try them as you say it opens up the transparency in the highs,the caps i use do a good job of this but ive always found these caps tend to high light this area to much at the expense of vocals and mid-bass,saying that i must say the amp is sounding quite good at the moment playing some "seal"
thanks for all the input and advice guys...feel free to keep it coming
smithie

 

[Haz]

AUDIO teflon capacitors

Can anyone tell me if this capacitors are suitable to replace the 2.2 uf input cap on the arjenhelder MKI TK2050 mono block class-D amplifier's?

Or is the rated too low? What would happen if you did?

0.033uF 500V AUDIO teflon capacitors K72P-6. Lot of 8 on eBay (end time 05-Dec-10 22:59:20 GMT)

Thank you for your support

 

[smithie]

hi haz
if you use this cap it shouldnt hurt(then again ive been wrong before),it may change your fq response,depends what your using to drive the boards with(pre-amp).
is there a reason your drawn to this cap,i know some give it good mention but i never came to the same conclusion,although like most things with caps it just depends where its used,of course this is only my view so it means nothing,if your out to test some ruskie caps then these may also be worth a try...k73-16.
all the best
smithie

 

[Nick122147]

Can anyone tell me if this capacitors are suitable to replace the 2.2 uf input cap on the arjenhelder MKI TK2050 mono block class-D amplifier's?

Or is the rated too low? What would happen if you did?

0.033uF 500V AUDIO teflon capacitors K72P-6. Lot of 8 on eBay (end time 05-Dec-10 22:59:20 GMT)

Thank you for your support

No bass. What makes you think you can exchange a 2.2uf part with a 0.033uf part?

 

[smithie]

there 3.3uf on my boards?
i dint notice the extra 0 there in your question
as nick says...your certainly have no bass,ive used 0.47 but as my lower reaches are covered by a plate amp i wouldnt hear any effect unless really drastic anyway
all the best
smithie

 

[Haz]

It was worth asking I thought, not entirely sure what the input caps do. I just like messing with things to see what effect it will have.

 

[Haz]

hi haz
if you use this cap it shouldnt hurt(then again ive been wrong before),it may change your fq response,depends what your using to drive the boards with(pre-amp).
is there a reason your drawn to this cap,i know some give it good mention but i never came to the same conclusion,although like most things with caps it just depends where its used,of course this is only my view so it means nothing,if your out to test some ruskie caps then these may also be worth a try...k73-16.
all the best
smithie

I was drawn to his cap due to another thread on this forum stating that this cap (K72P-6) and teflon capacitors in general are one of the best. Other reason are there priced very cheap!! And words like Military equipment and 0,5 grams of silver sound impressive!!

If anyone would like to throw some other brands my way that they would recommend I would be very grateful.

Thank you for you support!!

 

[alkasar]

Haz, you ask to change on ajenhelder's board; This is not the appropriate thread
For an input impedance of 50K, a 0.033µF cap would filter at 100Hz. Much too high and you would seriously lose bass.

If you want to try these caps as input caps, find some in the range of 2.2µF to 4.7µF.
Usually, people use MKP caps.

 

[Haz]

sorry should have started a new thread. I've got the information I needed Thank you.

 

[sendler]

Dayton foil

Dayton foil caps are my favorite paralleled to make 3.3uf. I've tried many popular MKP film caps for signal coupling and the foil caps are a step above in transparency. Foil over teflon might be even a little better but the pricing gets ridiculous.

 

[azertyman]

Hi

I want to make my first diy amp with the T1 board. I'll be using it to drive my old (but very nice) B&W DM2000 8ohm speakers.

I'm going to buy the following items:

- The new T1 2*100W@8ohm - ALPS
- Meanwell S-350 36V
- Case, some plugs...

Now, the website doens't say anything about speaker/DC protection, so I guess that T1 doens't have it. I've been reading about the hifimediy amps for a while and I can't seem to find alot of people implementing this protection. Do you need it? I hope someone can give me some more insight in this.


Thanks in advance

 

[terralune]

Hi.

Now, the website doens't say anything about speaker/DC protection, so I guess that T1 doens't have it. I've been reading about the hifimediy amps for a while and I can't seem to find alot of people implementing this protection. Do you need it? I hope someone can give me some more insight in this.


Thanks in advance

The protection you are asking about is already built in, so nothing to worry about