Destroyer x Amplifier DX HDII version. - Page 69 - diyAudio
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Old 28th March 2008, 09:17 PM   #681
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Default No my dear Andrew Now goodbuyer, as have bougth the Dx Amplifier idea!


So, now you're a good buyer..hehehehe

I have not tried those ones Andrew.

I am not very addicted to chip amplifiers...i know they have some advantage, and my bad english use the same pronouce to chip and cheap..ahahaha..so...they are almost the same in my mind.

Cheap is good.....so..... my brain accept chip as good too, because the sound they make into my tongue is the same..hehehehe..

But also, life shown me that is very rare to have cheap things that are very good too... the exception is our forum group buy....the boards are very cheap and parts are bougth by the cost price...and the work is made by our diyers.....so.... one of the rarities we have in our lives.... cheap and good...only our forum with group buy.

regards,

Carlos
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Old 28th March 2008, 09:35 PM   #682
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Ok

Thanks Carlos

Well I guess I'll re-use the parts.

I will be building HRII soon, will post pictures in the big thread if I can borrow a camera.

I will probably have questions for you.


p.s. The STK chip amp sounded cold, boring. But the bass was Very good. On some songs/tracks it was very good -- weird huh? THD was low.


See Ya!
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Old 28th March 2008, 11:49 PM   #683
udailey is offline udailey  United States
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Look what I found and bought 3 of
I think this is way overkill but they will work and work for many many projects.
ebay item
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Old 29th March 2008, 12:23 AM   #684
...truth seeker...
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udailey, That has home theater written all over it...
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Old 29th March 2008, 01:27 AM   #685
udailey is offline udailey  United States
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Thats why I bought 3
I am excited to figure out what subwoofer I am going to power with the third
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Old 30th March 2008, 09:30 AM   #686
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Nordic or Carlos,

Wich output drivers could be used without changing the values of the other components?
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Old 30th March 2008, 09:33 AM   #687
Nordic is offline Nordic  South Africa
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Hi Meany, you would have to give more details...

But I guess as long as the transistor is good enough for the voltages it sees it should be ok.. Also try to avoid high speed transistors.

For HRII, the common bd139/bd140 works perfectly.
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Old 30th March 2008, 10:29 AM   #688
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Default Use BD139 or TIP41/42, as those ones are the standard hardly tested


I have tried many others, and found the amplifier less stable.

MJ15032 into the VAS position made it unstable...into driver position had oscilations triggered by the signal.

I strongly suggest you to keep the schematic the way it is for safety reasons.

The way it is you have the guarantee of many units tested and built, using others, we cannot guarantee stability or reliability, as during tests i found problems using TIP35 into the output and some other transistor had problems too.

Very High Frequency units were tested into the differential and worked very bad, also they had lower gain compared to BC556 (for instance) that can have, sometimes, 550 of gain.

BD139 was used, since the seventies, in thousand of models and brands, even their cousines, MJE350/340 are not so reliable and so well accepted, had not the same reliability fame.

If you can, please, search for BD139 and BD140... they are already high speed, so, you gonna have good performance, but it is stable, has not enormous gain, but normally goes around 100, and this is more than enougth as drivers and VAS, were 50 of gain is already good.... those transistors are used, also into Radio Frequency transmitters, as they are able to oscilate (operate) into 100 Megahertz without too much losses.

Cannot find them, try Nordic, or try MJE340 and MJE350, and check the datasheet to see if leads are the same..... i have NOT tested those MJE340 and 350, so, i cannot guarantee they will operate fine...i suppose they will, but i have not sure.

You have bigger plastic option, the 2SC4793 and 2SA1837, mine most beloved transistors...those are stable and i have tested with them...but they are TO220 and looks very ugly and enormous compared to the board size.

regards,

Carlos
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Old 30th March 2008, 11:10 AM   #689
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Quote:
Originally posted by Nordic
Hi Meany, you would have to give more details...

Sorry Nordic,I ment the output transistors 2SC5200 and the 2SA1943 are their equal replacements for those?
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Old 31st March 2008, 05:13 AM   #690
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Carlos,

Wich one do you prefer regarding sound-quality
2SC3858- 2SA1494 or 2SC5200- 2SA1943?
Is there a difference in sound at all?
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