hi jens,
can you provide a bit more separation between T8 and T8A, T14 and T14A, T9 and T9A and T12 and T13A, reason is to be able to use to220's in this position.
likewise, can you make it 4 output transistors instead of 3, in keeping with djk's reccomendation of 2 plastics for a metal can, since the original super leach used 2 metal cans.
thanks
can you provide a bit more separation between T8 and T8A, T14 and T14A, T9 and T9A and T12 and T13A, reason is to be able to use to220's in this position.
likewise, can you make it 4 output transistors instead of 3, in keeping with djk's reccomendation of 2 plastics for a metal can, since the original super leach used 2 metal cans.
thanks
Tony said:
4 pairs mean that there should be room for 16!! TO-263 devises..... not really what I was after.
Maybe the layout can be remade with at daughter board on top of the output board....
Regarding the VAS and pre drivers I can change them to TO-220 but don't really understand why this is needed - is there some great transistor that I have missed?
\Jens
you don't have to change them to 220, just add maybe 2mm more clearance between them so that japanese toshiba transistors 2SA1837/2SC4793 can be used, they have the same footprints with the mje350/340 anyway.
Tony said:
It would not surprise me if these are 10 times faster than the 340/350s.
Lacking Ft and Cob on the datasheets of the MJEs looks very suspicious to me, strange for devices that have been around for such long time. Per Anders tried to find the numbers a few years ago, Spice simulations of the 340 and 350 have been unreliable.
Best i could find indicated an Ft of 10 MHz, 20 at most.
And a Cob of 30, more likely 50pF.
At minimum Hfe of the Toshibas is a mile ahead of the MJEs.
Up to 100volt rails the Toshibas should be a much better choice, a number have also posted as such, read even a couple of such posts here on diyaudio.
I already have the 1837/4793, BMM is at a stonethrow from my house and charges a really good rate.
Twisting the outer devices enables to place TO220s on the 10 device boards instead of TO126s.
Not as good as the 968/2238 set i think, the 1837 and 4793 are not fully complementary.
But if there is no difference between one board with 968B/2238Bs and the other with 1837/4793 i'll save a few of the Bs with a bonus of 30 volts extra on Vce.
A shame there is so much distance to your residence, Tony.
That must be a typo. Now i think of it i am sure DJK said 3 plastics to one metal, a 24-device Super Leach sounds much better.
What do you know, i happen to have about 50 !
You think this Toshiba talk will turn into a clipping post contest again ?
hi,
i intend to use the 2SA1837/2SC4793 in the vas and first of the triple, then for drivers, i intend to use the MJW1302/MJW3281 and for output tranies, MJL1302/MJL3281.
i am still scouting for to126 tranies to use in the input stages.
i have several pairs of the 2SA1837/2SC4793 , they were pulled out from boards from an export factory here that had production overrruns, i am certein they are not fakes. they drive 2sc5200 tranies.
maybe jens can do a sim using these tranies, no?
anyway, let us hear from the other members what they think about the output tranie numbers in the ouput stage!
do i smell a group buy?
i intend to use the 2SA1837/2SC4793 in the vas and first of the triple, then for drivers, i intend to use the MJW1302/MJW3281 and for output tranies, MJL1302/MJL3281.
i am still scouting for to126 tranies to use in the input stages.
i have several pairs of the 2SA1837/2SC4793 , they were pulled out from boards from an export factory here that had production overrruns, i am certein they are not fakes. they drive 2sc5200 tranies.
maybe jens can do a sim using these tranies, no?
anyway, let us hear from the other members what they think about the output tranie numbers in the ouput stage!
do i smell a group buy?
Tony said:
Unlikely that the popularity of this pair is large enough to make it interesting to fake them yet, seems to me that so far only the most familiar numbers have been copied.
Which could change very rapidly of course, if these become more popular.
In Europe i know of near to 10 shops that sell them, price differences are marginal and all rates at are original item level.
I am allways smelling GB, be it for a 16, 20 or 24 device board.
Both Terry and I expressed we are interested in a Super Leach board a year ago.
Before I spend more time on the huge layout with 16 or more output transistors, I think that interested builder should decide what heatsink to use so I have a better chance of getting the layout done in a way that is actually useful.
I suggest going for Conrad products as they ship everywhere in the world and a priced ok.
How about the MF35-151.5? It is 35 cm long and has room for 16 output transistors with my current layout.
I suggest going for something like what I already posted, but I more output devises are needed the board gets really long and the layout is no longer practical.
Please comment on choice of heatsink and number of output devises (Jacco below 50 please 😉 )
\Jens
I suggest going for Conrad products as they ship everywhere in the world and a priced ok.
How about the MF35-151.5? It is 35 cm long and has room for 16 output transistors with my current layout.
I suggest going for something like what I already posted, but I more output devises are needed the board gets really long and the layout is no longer practical.
Please comment on choice of heatsink and number of output devises (Jacco below 50 please 😉 )
\Jens
Jens suggested:
I believe Jens has a very good idea. Conrad says surface shipment should allow 10-12 weeks for delivery. There are other more costly options. The current exchange rates for the suggested sink @ 53.36 aud are
~$40.00 usd
~ 33.08 euro, each piece+shipping, etc.
This sink has 0.21 C deg. / Watt @ 80 deg. and weighs 2.56 kg.
Did I say I'm interested? .....err, I am, lotsa watts, and stable.
I believe Jens has a very good idea. Conrad says surface shipment should allow 10-12 weeks for delivery. There are other more costly options. The current exchange rates for the suggested sink @ 53.36 aud are
~$40.00 usd
~ 33.08 euro, each piece+shipping, etc.
This sink has 0.21 C deg. / Watt @ 80 deg. and weighs 2.56 kg.
Did I say I'm interested? .....err, I am, lotsa watts, and stable.
Updated layout.
16 output transistors.....
700kb download
http://www.delta-audio.com/temp_jens/Super_Leach_ver_1.4_PCB.pdf
\Jens
16 output transistors.....
700kb download
http://www.delta-audio.com/temp_jens/Super_Leach_ver_1.4_PCB.pdf
\Jens
jens,
with your permission - can i post a wiki page for the group buy so we'll have idea who's with us ?
roland
with your permission - can i post a wiki page for the group buy so we'll have idea who's with us ?
roland
jens,
awsome! i like it.
roland,
we have to get the board prototyped first, let us hear what others have to say.
awsome! i like it.
roland,
we have to get the board prototyped first, let us hear what others have to say.
So has any other had time to review the layout?
What are your thoughts regarding heatsinking?
roland, a wiki page would be ok, but the layout needs to be tested before we start the group buy.
\Jens
What are your thoughts regarding heatsinking?
roland, a wiki page would be ok, but the layout needs to be tested before we start the group buy.
\Jens
Hi Jens,
just a quick look;
why series caps C34/38 for the output? Leach(2.1a) shows C25 as a single cap.
Why have you reverted to the Global Feedback path of the 5pair PCB rather than the 3pair?
I have found it impossible to find and/or fit polypropylene caps into the small footprints on the 3pair PCB. Any chance you can give more space for this option and alternative pin pitch for these bigger caps?
The electrolytics are similarly confined by adjacent components. Can you move some of these close by components slightly to allow different footprint electros? Thus giving your followers a chance to use alternative manufacturers and/or values/sizes.
just a quick look;
why series caps C34/38 for the output? Leach(2.1a) shows C25 as a single cap.
Why have you reverted to the Global Feedback path of the 5pair PCB rather than the 3pair?
I have found it impossible to find and/or fit polypropylene caps into the small footprints on the 3pair PCB. Any chance you can give more space for this option and alternative pin pitch for these bigger caps?
The electrolytics are similarly confined by adjacent components. Can you move some of these close by components slightly to allow different footprint electros? Thus giving your followers a chance to use alternative manufacturers and/or values/sizes.
Why series caps C34/38 for the output? Leach(2.1a) shows C25 as a single cap.
I figured that somebody might run the amp at close to 100V rails and thus I desided to have the Zobel network contain 2 x 100V caps to ensure that they are keept within their spec.
Why have you reverted to the Global Feedback path of the 5pair PCB rather than the 3pair?
This is bugging me too, but I ran out of space and figured that it would be better to have the feedback on the same layer as the output and to avoid any vias in that signal path as someone building their own PCB might be in trouble should the feedback path fail due to bad solder joint or similar.
I have found it impossible to find and/or fit polypropylene caps into the small footprints on the 3pair PCB. Any chance you can give more space for this option and alternative pin pitch for these bigger caps?
I use the Evox MMK series for all my amps, they are rugged and performs well in high voltage applications.
The electrolytics are similarly confined by adjacent components. Can you move some of these close by components slightly to allow different footprint electros?
To where should I move the components? There is not much room left... please advise
\Jens
I figured that somebody might run the amp at close to 100V rails and thus I desided to have the Zobel network contain 2 x 100V caps to ensure that they are keept within their spec.
Why have you reverted to the Global Feedback path of the 5pair PCB rather than the 3pair?
This is bugging me too, but I ran out of space and figured that it would be better to have the feedback on the same layer as the output and to avoid any vias in that signal path as someone building their own PCB might be in trouble should the feedback path fail due to bad solder joint or similar.
I have found it impossible to find and/or fit polypropylene caps into the small footprints on the 3pair PCB. Any chance you can give more space for this option and alternative pin pitch for these bigger caps?
I use the Evox MMK series for all my amps, they are rugged and performs well in high voltage applications.
The electrolytics are similarly confined by adjacent components. Can you move some of these close by components slightly to allow different footprint electros?
To where should I move the components? There is not much room left... please advise
\Jens
Hi Jens,
this is a bit long winded so I will devide it into 2posts.
Is it possible to re-align ALL the electrolytics to face the same way so that the Negative label faces towards the negative side of the PCB (makes checking after PCB assembly easier)?
Move D1,2,3&4 up about 0.05inch.
Move Vsf> about 0.1inch. Adjust Vs to fit.
Move C11< about 0.1inch.
Centre C10 down 0.05inch.
Add pad to C10 to give 0.2inch + 0.3inch pin pitch.
Move Vcf< about 0.1inch.
Move C4 beside or above Vcf (near the VIAs).
Re-arrange the tracks from D1 to Vcf to minimise the track lengths for C4.
Move C3 down about 0.05inch.
Add pad to C3 to give 0.2inch + 0.3inch pin pitch.
Track lengths to C3 are less important than to C4 so small extension tracks to C4 are OK.
This same re-arrangment can also be applied to C11 to give it less track inductance.
Jens,
give me some feedback on these modifications before I make some layout suggestions for C1, C12 & C14.
this is a bit long winded so I will devide it into 2posts.
Is it possible to re-align ALL the electrolytics to face the same way so that the Negative label faces towards the negative side of the PCB (makes checking after PCB assembly easier)?
Move D1,2,3&4 up about 0.05inch.
Move Vsf> about 0.1inch. Adjust Vs to fit.
Move C11< about 0.1inch.
Centre C10 down 0.05inch.
Add pad to C10 to give 0.2inch + 0.3inch pin pitch.
Move Vcf< about 0.1inch.
Move C4 beside or above Vcf (near the VIAs).
Re-arrange the tracks from D1 to Vcf to minimise the track lengths for C4.
Move C3 down about 0.05inch.
Add pad to C3 to give 0.2inch + 0.3inch pin pitch.
Track lengths to C3 are less important than to C4 so small extension tracks to C4 are OK.
This same re-arrangment can also be applied to C11 to give it less track inductance.
Jens,
give me some feedback on these modifications before I make some layout suggestions for C1, C12 & C14.
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