Jump to content

What Are You Building Today


Recommended Posts

Some progress. Replaces the original battery in my DIY T2, which was supposed not to be modified in any way…

IMG_0459.thumb.JPG.77fe6d84461e1c18f5cc3f17e038839b.JPG         IMG_0461.thumb.JPG.e8949d00bc5251a501c1fdbd7a79b4a6.JPG

Schematic:

96399946_Skrmklipp.thumb.JPG.475011eb5ee08e66200e7a7b06207084.JPG

  • Like 2
  • Haha 1
Link to post
Share on other sites
  • Replies 670
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

So Tice removed a deck at his job site, which is Armistead Maupin's former home. In his genius he recognized it to be Brazilian Ipe that was only screwed down from one side. The new owner eventually a

The Cherry is lighter than the speakers, but will darken quickly next to the window. I have a vented front plate coming for the top space. The cooling fan sits in that space, and is really quiet.

Second coat of finish. I still have rack rails to install, to hold the gear. The holes are vents, which will get black mesh behind them.

Posted Images

Hello guys, after a long time, and with a lot of time in my hands due to quarantine I finally finished my Dynalo MK2 mini and reterminated my hd650 with a 4 pin balanced plug. 

Transistors are a bit hotter than I wanted, at 90-100 degrees with the top panel on. I need to go read about reducing bias.

Sounds good though! Source at the moment is a bluesound node, need to go and find a better DAC with balanced out that doesn't break the bank.

 

20200402_153642.jpg

  • Like 5
Link to post
Share on other sites

I’m trying to finish re-flow oven in my spare time when normal people are sleeping, lol. 
 

It’s missing insulation, servo arm and that’s about it. A little touch up to the truck bed liner paint as well. 
 

 

85928409-69D4-4F61-9DFF-92106A3717DA.jpeg

  • Like 2
Link to post
Share on other sites
10 hours ago, MASantos said:

 need to go and find a better DAC with balanced out that doesn't break the bank.

I use the el cheapo iFi Zen DAC ($129) to feed my Dynalo/Dynahi/Megatron/Carbon with satisfactory result. Providing a healthy 4Vrms, it can also works as a preamp. You need to build a custom 4.4mm-XLR cable though. It’s hard to believe I can get that many features from a commercial product for such a low price.

Link to post
Share on other sites
14 hours ago, MASantos said:

Hello guys, after a long time, and with a lot of time in my hands due to quarantine I finally finished my Dynalo MK2 mini and reterminated my hd650 with a 4 pin balanced plug. 

Transistors are a bit hotter than I wanted, at 90-100 degrees with the top panel on. I need to go read about reducing bias.

Sounds good though! Source at the moment is a bluesound node, need to go and find a better DAC with balanced out that doesn't break the bank.

 

20200402_153642.jpg

Good to hear from you Manuel! And nice work while sheltered. 

  • Like 1
Link to post
Share on other sites

A version of mini T2 with active batteries.

533528209_Skrmklipp2.thumb.JPG.f5b7fb734ef105fbfcbd94860ac5b54a.JPG

Battery has lt1021 voltage reference and a current sink ensures it works properly. Under batteries and input tubes is a small circuit (in the yellow circle) – same circuit in DIY T2 has five 2sc3675.

 

Only exists in fantasy. 

Edited by JoaMat
  • Like 5
Link to post
Share on other sites
  • 2 weeks later...
On 3/1/2020 at 4:11 PM, Kerry said:

I just milled this board for a CNC probe I’m working on.   

C63952C4-6899-469E-AA5C-70F819C3660B.thumb.jpeg.e83f6427963f37b3ff0dab7f3e116ebf.jpeg

Those are .01” slots. I’m surprised I could do this :) 

May I ask - what software did you use to create files for CNC machine?

Link to post
Share on other sites

I exported dxf files from eagle and imported that into fusion 360. I had to build tool paths for traces. It would be tedious if there were a lot of traces, but I complete control over the routing. 

Edited by Kerry
  • Thanks 1
Link to post
Share on other sites

One CFA board done. Small BJTs were incredibly close matched in the tape reel. A few decimals of mA between them. 

RN60 resistors, and 3W CMF at the outputs.

20200417_165232.thumb.jpg.a601eb160ee76e2d7f4f72b558bf70c0.jpg

20200417_165241.thumb.jpg.b3055ae74c6785f9edb67dfbf28782de.jpg
Edited by MASantos
  • Like 1
Link to post
Share on other sites
32 minutes ago, MASantos said:

What case did you get for yours? Looking around for options but I either find too big or too small

Remind us are you picking a chassis for a singll-ended or balanced build? PSU in the same chassis or separate chassis? 

Link to post
Share on other sites

I am building a single chassis single ended version. I thought about something like this: 

It could be a small cube about 14-16 cm sides. everything bolting to the heatsinks. I would have to make it myself though.

Commercially I found some aceptable options:

https://www.audiophonics.fr/en/aluminium-boxes-cases/diy-case-amplifier-100-aluminium-271x240x90mm-p-9499.html

15872393741204537559056263812235.jpg

Link to post
Share on other sites

The chassis you showed should work if you can fit everything in. It looks to me a similar chassis to the one I am using for mine. I posted photos of it when I had the PSU built in. Mine is a balanced amp.

Maybe consider moving this discussion to the thread dedicated to the dynamic CFA build. 

 

 

 

 

Edited by mwl168
Link to post
Share on other sites

Since there is no "What Are You Destroying Today" thread I post here.

 

Yesterday, while trying a modification to a battery on the T2 that was meant not to be modified in any way I had a "gun shot" when high voltages were applied.

 

I had to replaced three mosfets, two  zeners, and one power resistor in PSU. Amplifier needed four c3675, three k216, only one j79 and two leds.

Now I’m happy again.:D

 

Some broken parts in a small cup. RIP.
IMG_0472.thumb.JPG.568c1968ae8aaf66fb3504118308f867.JPG

Edited by JoaMat
  • Thanks 1
  • Haha 3
  • Sad 1
Link to post
Share on other sites

Thank you. Using a T2 amplifier as a test bench might be… not so smart.

 

Milled this test board today. On heat sinks; 10m90s current sink to the right and high voltage npn to the left.

IMG_0473.thumb.JPG.79053cbdf8618595c15ee786457b6ca3.JPG 

The small board on the left is the battery that killed my T2. :mikey2:

  • Like 2
Link to post
Share on other sites

Made a new small board. All components moved to one side and a sot-223 1200V npn added to form a Darlington pair with the big npn in the battery.
IMG_0301.thumb.JPG.b6ff516ed482c1f668a5067d2c4aa3bc.JPG

It’s possible to use it with Kevin’s original DIY T2 board. Remove battery components from main board and solder in the daughter board (three pins, fits right in) if you dare. Myself I’m a bit shaky after last failure.

  • Like 6
Link to post
Share on other sites

Just removed stn0214 (the sot-223 device mentioned above). The npn I use on test board is fjpf2145. It has lower hFE than 2sc3675 and battery on test board is not capable to drive the fjpf2145 alone, it needs the Darlington pair.

 

For reference, https://www.head-case.org/forums/topic/6837-the-ultimate-diy-a-stax-srm-t2/?do=findComment&comment=419666 , here Kevin wrote about darlington out of a pair of 2sc4686. I believe hFE for 2sc4686 is even lower than for fjpf2145.

Link to post
Share on other sites

IME yes the 2SC4686s have very low hFE. The last batch I bought all measured 22 and to be honest I thought the tester was broken until I checked the data sheet and saw that this is actually with specs (albeit at the low end).

Link to post
Share on other sites
1 hour ago, JoaMat said:

Just removed stn0214 (the sot-223 device mentioned above). The npn I use on test board is fjpf2145. It has lower hFE than 2sc3675 and battery on test board is not capable to drive the fjpf2145 alone, it needs the Darlington pair.

 

For reference, https://www.head-case.org/forums/topic/6837-the-ultimate-diy-a-stax-srm-t2/?do=findComment&comment=419666 , here Kevin wrote about darlington out of a pair of 2sc4686. I believe hFE for 2sc4686 is even lower than for fjpf2145.

Hi JoaMat:

Have you considered experimenting with STP03D200 in the active batteries to replace the 2SC3675? It's a 2KV Darlington transistor with hFE > 200. This part was actually mentioned in the DIY T2 thread long time ago. It's a current production part available from Mouser, etc. and expensive (> $6 US) but still cheaper than 2SC3675 and much easier to source.  

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...