[f] AMB on Facebook

SuSy dynahi v2

Kevin Gilmore's higher-powered version of the dynalo

Re: SuSy dynahi v2

Postby DEFL » May 31st, 2015, 12:19 pm

mloutfie wrote:the silkscreen and the schematic (dynabal9.zip vs dynabalbjt.pdf) capaitor and resistor value doesnt match (taken from http://gilmore.chem.northwestern.edu/boards/)

Hmm, where do you find discrepancy?
DEFL
 
Posts: 175
Likes: 8 posts
Liked in: 4 posts
Joined: August 2nd, 2013, 2:26 am
Location: Saint-Petersburg
Country: Russia (ru)

Re: SuSy dynahi v2

Postby amb » May 31st, 2015, 1:52 pm

2SC3421/2SA1358 are what was specified for the original (non-SuSy) dynahi too. I built mine with 2SC3421Y/2SA1358Y and had no trouble with matching or biasing. But I did have a fairly good number of them to choose from at the time. I don't have them any more. Note that the these transistors have reverse pin-out compared to the MJEs.

I have no personal experience with the other transistors you mentioned, as far as matching is concerned. But looking at the datasheets the MJE15034/MJE15035 has more than double the hfe than MJE15030/MJE15031. Higher hfe is better in this circuit because it reduces the load on the VAS stage and give better performance. But the Toshibas have much higher fT figures which are also desirable.

No matter which other transistors you use, the compensation capacitor value will likely need to change due to differing junction capacitances.
User avatar
amb
Site Admin
 
Posts: 10457
Likes: 182 posts
Liked in: 498 posts
Joined: March 29th, 2010, 9:49 pm
Location: Sunnyvale, CA
Country: United States (us)

Re: SuSy dynahi v2

Postby DEFL » May 31st, 2015, 2:26 pm

Thanks for reply.
amb wrote:Note that the these transistors have reverse pin-out compared to the MJEs.

Yes, and that's the problem (I'm using version with on-board heatsinks).

amb wrote:No matter which other transistors you use, the compensation capacitor value will likely need to change due to differing junction capacitances.

Which one do you mean? The one that was discussed above (in pf range) and which determines RC constant?
BTW, I checked schematic with Toshiba and On Semi parts, it's identical.

And what about 2SC5171/2SA1930? They are pin to pin compatible. Hfe is very good. Got it that you didn't try, but at least specs-wise, any evident reason not to use it?
DEFL
 
Posts: 175
Likes: 8 posts
Liked in: 4 posts
Joined: August 2nd, 2013, 2:26 am
Location: Saint-Petersburg
Country: Russia (ru)

SuSy dynahi v2

Postby amb » May 31st, 2015, 2:45 pm

Yes the compensation caps are the small pF value ones that are in parallel with the feedback resistors.
If you can find the 2SC5171/2SA1930, they're worth a try.
User avatar
amb
Site Admin
 
Posts: 10457
Likes: 182 posts
Liked in: 498 posts
Joined: March 29th, 2010, 9:49 pm
Location: Sunnyvale, CA
Country: United States (us)

Re: SuSy dynahi v2

Postby mloutfie » May 31st, 2015, 8:43 pm

DEFL wrote:
mloutfie wrote:the silkscreen and the schematic (dynabal9.zip vs dynabalbjt.pdf) capaitor and resistor value doesnt match (taken from http://gilmore.chem.northwestern.edu/boards/)

Hmm, where do you find discrepancy?


I am comparing
http://gilmore.chem.northwestern.edu/bo ... balbjt.PDF
with my board that is
http://gilmore.chem.northwestern.edu/bo ... hibal9.zip

Discrepancy is the 20 ohm resistor is 10ohm in the schematic and the 470uF caps is nowhere in the schmaticand some rersistor that I can't find matching value in the board (for example r6 and r16). I might be looking at the wrong thing but I think it's the latest schematic.
mloutfie
 
Posts: 54
Likes: 8 posts
Liked in: 2 posts
Joined: April 20th, 2015, 6:50 am
Location: Melbourne
Country: Australia (au)

Re: SuSy dynahi v2

Postby DEFL » May 31st, 2015, 11:52 pm

amb wrote:If you can find the 2SC5171/2SA1930, they're worth a try.

Thanks, ordered 50 pcs of each. The rest will go for Krell KSA5 clone.
DEFL
 
Posts: 175
Likes: 8 posts
Liked in: 4 posts
Joined: August 2nd, 2013, 2:26 am
Location: Saint-Petersburg
Country: Russia (ru)

Re: SuSy dynahi v2

Postby DEFL » June 1st, 2015, 12:02 am

mloutfie wrote:
DEFL wrote:
mloutfie wrote:the silkscreen and the schematic (dynabal9.zip vs dynabalbjt.pdf) capaitor and resistor value doesnt match (taken from http://gilmore.chem.northwestern.edu/boards/)

Hmm, where do you find discrepancy?


I am comparing
http://gilmore.chem.northwestern.edu/bo ... balbjt.PDF
with my board that is
http://gilmore.chem.northwestern.edu/bo ... hibal9.zip

Discrepancy is the 20 ohm resistor is 10ohm in the schematic and the 470uF caps is nowhere in the schmaticand some rersistor that I can't find matching value in the board (for example r6 and r16). I might be looking at the wrong thing but I think it's the latest schematic.

Output resistors are doubled to reduce the load, so there are 32 of 20Ohm resistors instead of 16 10Ohm resistors. The resulting reisitance is the same.
Electrolytic caps are rail caps, you can even omit them.
R6 and R16 (5K) are there, just count the number of 5K resistors, there are 7 pcs per board both in schematic and on the board.

mloutfie likes this post.
DEFL
 
Posts: 175
Likes: 8 posts
Liked in: 4 posts
Joined: August 2nd, 2013, 2:26 am
Location: Saint-Petersburg
Country: Russia (ru)

Re: SuSy dynahi v2

Postby mloutfie » June 1st, 2015, 4:38 pm

DEFL wrote:
Output resistors are doubled to reduce the load, so there are 32 of 20Ohm resistors instead of 16 10Ohm resistors. The resulting reisitance is the same.
Electrolytic caps are rail caps, you can even omit them.
R6 and R16 (5K) are there, just count the number of 5K resistors, there are 7 pcs per board both in schematic and on the board.

Yeah you're right actually :)
mloutfie
 
Posts: 54
Likes: 8 posts
Liked in: 2 posts
Joined: April 20th, 2015, 6:50 am
Location: Melbourne
Country: Australia (au)

Re: SuSy dynahi v2

Postby mloutfie » June 1st, 2015, 4:43 pm

When I'm testing the board I can see it's only drawing 0.22A for 2 boards. Considering I'm only setting it to a gain of 4 in each board. Is 2 sigma22 power board really necessary? seems to be an overkill with no gain at all
mloutfie
 
Posts: 54
Likes: 8 posts
Liked in: 2 posts
Joined: April 20th, 2015, 6:50 am
Location: Melbourne
Country: Australia (au)

Re: SuSy dynahi v2

Postby amb » June 1st, 2015, 10:33 pm

0.22A sounds low. Each output bank should draw about 300mA when biased properly, and there are two banks per channel.
1.2A is a bit much for a single σ22 with the standard PCB-mount heatsinks.

The amp's gain has nothing to do with power supply current draw.
User avatar
amb
Site Admin
 
Posts: 10457
Likes: 182 posts
Liked in: 498 posts
Joined: March 29th, 2010, 9:49 pm
Location: Sunnyvale, CA
Country: United States (us)

PreviousNext

Return to dynahi headphone amplifier

Who is online

Users browsing this forum: No registered users and 0 guests

Quick Links

AMB audio DIY resources
AMB audio shop