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The Multi Amp aka Dynalo Mk2


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Here's an update on the mini. I've got the external regs running now.  This thing does throw off quite a bit of heat.  I've some sinks on the output transformers now, but I'd like to make them a

Almost there.  I've got one channel dialed in and working on the second.   

Well that was very quick shipping from FPE , Initially I was going for an all out black box, but FPE don’t do anodising after milling leaving the panels with silver edges, which got me thinking s

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I got the multi amp boards from Birgir, marked multi amp rev 1.0. After looking at my pcbs, other than a lot of differing parts values on the silkscreen compared to the schematic, I think it's basically the production board design except there's a missing 10k resistor by the servo, there are spots for the 4.7uf decoupling caps, and r21/r25 are combined into a single 20k resistor. I can't really tell what the 10k is connected to from your pic, could you tell me?

 

Edit: Nevermind, found it. It's connected in between r21 and r25. May have to offboard those resistors.

Edited by mypasswordis
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Just (hopefully) bought all the parts needed to build the KGITSOCH minus the LSJ74s which go for a mind-numbing ~$6 a pop in sets of 8 at diyaudio, and the case which I probably won't get for a long time. Any of you buy the LSJ74s and have good success with matching?

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:( Okay well I'll just get a set of eight and the closest four of the eight will be the ones I use. Audio stuff is making my wallet take too massive of a beating. Probably gonna have to order the THAT340 for the Multi Amp boards unless the other four are relatively close.

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I have a bunch of matched jfets I was planning to list, but life is too crazy now... I drug them out of a pile and moved them to yet another pile and am not sure where they are, or I would check. Hit me up week after next and I should be able to have time to locate them.

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I have a bunch of matched jfets I was planning to list, but life is too crazy now... I drug them out of a pile and moved them to yet another pile and am not sure where they are, or I would check. Hit me up week after next and I should be able to have time to locate them.

 

Thanks, will do!

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not bad for a senior citizen ;D

http://gilmore.chem.northwestern.edu/dynalobalss.jpg

 

I don't even do any metal work by hand anymore, even for

the bottom panel which is just 8 holes, I do it in the NC mill

and unlike Mikhail the holes end up in the right place the

first time.

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Not bad old man!!!  :)   I guess this means I have to build mine? 

 

I sure could use the NC mill having done 7 front panels by hand today... 

 

Hey Spritzer, what does your FET and transistor test/matching circuit look like? Am I fine just going off AMB's examples - Device matching? There are so many different test circuit suggestions ><

 

Gonna try to get a matched FET quad from FETaudio too

 

The B22 stuff will do just fine but you can build this amp without any matching and it will work just fine. 

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parts list in progress

so with the pot its about $300 in parts.

need mounting screws, standoff's etc...

 

item   #    $ 
240 ohm 4 0.2 0.8
680 ohm 8 0.2 1.6
402 ohm 12 0.2 2.4
2.74k ohm 8 0.2 1.6
3.01k ohm 8 0.2 1.6
24.9k 4 0.2 0.8
5k 4 0.2 0.8
10k 6 0.2 1.2
49.9k 8 0.2 1.6
100k 4 0.2 0.8
20 ohm 32 0.2 6.4
14 pin ic socket   0.97
1uf 4  0
5pf 4  0
100uf 8  0
4.7uf 8 2.37 18.96
op07 4  1.56 6.24
that340 2 6.4 12.8
mpsw56 22 0.44 9.68
mpsw06 22 0.51 11.22
led 4  0
10k pot 6  0
haa15-.8-ag   63.63
boards 2 10 20
galaxy 288   69
rk27 quad   
neutrik chassis female 5 4.29 21.45
   
   
   253.55

Edited by kevin gilmore
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This is what I put together for the amp board only....any errors or suggested changes let me know:

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=33c64fee31

This has R38/39 reduced to 200ohm for 20V rails so I can jack my KSA5 power supply into it.

Also could not find reel or tape for the mpsw06 so went with straight legs. Typically I prefer the prebent legs.

Tempted to put it in the galaxy chassis like you did with that haa15....

parts list in progress

so with the pot its about $300 in parts.

need mounting screws, standoff's etc...

item # $

240 ohm 4 0.2 0.8

680 ohm 8 0.2 1.6

402 ohm 12 0.2 2.4

2.74k ohm 8 0.2 1.6

3.01k ohm 8 0.2 1.6

24.9k 4 0.2 0.8

5k 4 0.2 0.8

10k 6 0.2 1.2

49.9k 8 0.2 1.6

100k 4 0.2 0.8

20 ohm 32 0.2 6.4

14 pin ic socket 0.97

1uf 4 0

5pf 4 0

100uf 8 0

4.7uf 8 2.37 18.96

op07 4 1.56 6.24

that340 2 6.4 12.8

mpsw56 22 0.44 9.68

mpsw06 22 0.51 11.22

led 4 0

10k pot 6 0

haa15-.8-ag 63.63

boards 2 10 20

galaxy 288 69

rk27 quad

neutrik chassis female 5 4.29 21.45

253.55

Edited by GrindingThud
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This is what I put together for the amp board only....any errors or suggested changes let me know:http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=33c64fee31

This has R38/39 reduced to 200ohm for 20V rails so I can jack my KSA5 power supply into it.

Also could not find reel or tape for the mpsw06 so went with straight legs. Typically I prefer the prebent legs.

Tempted to put it in the galaxy chassis like you did with that haa15....

FWIW: Kevin's BOM lists 4x OP07 a single opamp, and your Mouser BOM lists 2x OP275GPZ, dual opamps with a different pinout.

Edited by Laowei
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Doh, that was supposed to be OP27, not 275. Good catch! :)

Also, I did the BOM per board, so quantities are half.

FWIW: Kevin's BOM lists 4x OP07 a single opamp, and your Mouser BOM lists 2x OP275GPZ, dual opamps with a different pinout.

Edited by GrindingThud
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the lead spacing on the board for the .1uf cap is 3.5mm but the .1inch caps do fit.

 

the 5pf caps are 5mm lead spacing

 

by the way, I have a new name for the thing...

 

PureBipolar    (tm&c)

 

would apply to the ss dynahi too.

Edited by kevin gilmore
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Gotta love a little Bipolar now and then.... :)

Speaking of bipolar, how do you like that haa15 PSU? Is it quiet? Was thinking of using that with maybe a little off board capacitance if it needed it. The Krell went overboard with capacitance....this design seems much leaner.

Thanks for clarifying the spacings

 

by the way, I have a new name for the thing...

 

PureBipolar    (tm&c)

 

would apply to the ss dynahi too.

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