The art of Sen
- Thread starter Bemused
- Start date
Jo Sharp
Pulls on doors marked push
Glad to be of service, Sir; invoice is in the post..
The Sen V18 kit is available on its own
2x pcb
4x type 1 heat sink
4 x type 2 heat sink
£38
As above but including
16 x matched Jfets
£85
From Patrick
I think this may mean our Buffalos, not quite sure.
The push-pull and V18 has got me a little lost but the prices look good.
Any thoughts
2x pcb
4x type 1 heat sink
4 x type 2 heat sink
£38
As above but including
16 x matched Jfets
£85
From Patrick
I think this may mean our Buffalos, not quite sure.
The push-pull and V18 has got me a little lost but the prices look good.
Any thoughts
flashgo
DIY Practitioner
First, count me in. I really like the idea of a drop-in replacement for the Legato.
Second, the kit price is not unreasonable. The Legato w/o buffers is $90. Perhaps we could design a Buffalo-aligned PCB and purchase the rest via GB from Patrick? How would the heat sinks work relative to an overlaying Buffalo?
Yes but I still think there is some difference in the Xen kit
re
Perhaps someone could clarify, maybe I should go and ask Patrick?
Prices look better when we don't have to buy the whole shebang including the Cens.
A whole load of matched Jfets is one PITA less your well organized and have stocks.
Easy to do an adapter to fit the Sen to Buffalo, hell we could even make the adapter one huge ground plane just in case any nastys jump cross, well there is a 100MHz clock just above...
A big thing to point out is the cost of the matched Jfets and Heat sinks, once glued up they can not be re used in another board. If we continue with a diy etch I would use some dirt cheap TO92s to prove the fit and sinks etc.
Some info I picked up
One is called CEN which means complementary (i.e. 2SK170BL/2SJ74BL), or push-pull.
The other is called SEN, which means singled ended.
CEN V18 means CEN IV Version 18, designed specifically for ES9018 (hence V18)
SEN V18 means SEN IV Version 18, without saying.
Posted some Qs on the DIYA thread post 1006
Keeping fingers crossed for a layman's answer
Thoughts gentlemen please
Btw
I have edited post one to reflect Patrick's position - please have a read.
Hi
SEN is a single ended circuit- it uses a (pair of) single N-type JFet(s), as a transconductance amplifier, (each) fed by an identical fet connected as a contant current source. CEN is push pull, and uses a complementary pair of N-type and P-type JFets. V18 is just the version of the pcb, marked on both the SEN and CEN boards (V 18.0). The 18 refers to the ESS9018 the boards are intended to serve
Paul N
SEN is a single ended circuit- it uses a (pair of) single N-type JFet(s), as a transconductance amplifier, (each) fed by an identical fet connected as a contant current source. CEN is push pull, and uses a complementary pair of N-type and P-type JFets. V18 is just the version of the pcb, marked on both the SEN and CEN boards (V 18.0). The 18 refers to the ESS9018 the boards are intended to serve
Paul N
I've been keeping an eye on this on DIYA for a while as I intend to add a discrete output stage to my Arcam Alpha and its TDA1541A DAC. It would be good to get a pfm PCB going. What will the power dissipation of the Jfets be - can they be mounted face to face, tied together with a cable tie to get a thermal bond (with compond inbetween them)?
Hi Paul
I am afraid I suddenly lost the plot and got a little confused thinking there were new varients, still not sure were / when the V18 came into the picture.
Is your version the Sen V18
Am I right in saying Sen V18 takes the balanced outputs from the Sabre +/0/- and uses 8 Jfets in two quad pairs and provides a balanced output to which we still need to add a balanced to singe ended converter.
I did not pay much attention to the Cen as yesterday I thought Sen was the way to go.
Is Patrick sugesting the Cen would be better?
I am afraid we may be giving Patrick some worry as misinformation is very difficult to correct or to recall.
From Patrick
Good to have you looking in I am sure your expertise can help us.
I have only being looking at Sen for a few days, it sounds like your well advanced.
You may get your answer directly from Patrick
I believe thermal stability is critical for output offset stability.
Your point of dissipation is a good consideration, back to back tieing could perhaps work with the Cen using pairs so long as dissipation is low but perhaps not the Sen using quads.
I do not think there will be a pinkfish production board, only diy etch or diy milling as this is Patrick product and we are only considering a diy adaption to suit the Buffalo.
Initially costs seemed high as we had to purchase the whole evaluation kit but Sen is now offered individually and looks attractive.
From Patrick
Some thoughts from my side:
I don´t know how the supply situation for the needed 2SK369V is, but if there would be a groupbuy for those, the matching of 16 JFETS had to be done by someone. Has anybody an idea how much FETs would be needed to match, let´s say, 10 sets of 16 FETs? How closely should they be matched?
On the other hand, the SEN-evaluation kit provides everything we need, for a reasonable price, I guess. All that is missing is a PCB that would take all the FETs, heatsinks and fit under the buffalo.
Which program do you use to model your PCBs, Tony? I always used Vectorworks, a CAD tool on the mac, but maybe it is time to get something more professional, Also, this way we could share or complement each others layouts. A ground plane between buffalo and SEN is a good idea by the way. Since the supply is floating, EMI seems to be an issue. One has to be careful about the maximum height and via-connectors here .
I don´t know how the supply situation for the needed 2SK369V is, but if there would be a groupbuy for those, the matching of 16 JFETS had to be done by someone. Has anybody an idea how much FETs would be needed to match, let´s say, 10 sets of 16 FETs? How closely should they be matched?
On the other hand, the SEN-evaluation kit provides everything we need, for a reasonable price, I guess. All that is missing is a PCB that would take all the FETs, heatsinks and fit under the buffalo.
Which program do you use to model your PCBs, Tony? I always used Vectorworks, a CAD tool on the mac, but maybe it is time to get something more professional, Also, this way we could share or complement each others layouts. A ground plane between buffalo and SEN is a good idea by the way. Since the supply is floating, EMI seems to be an issue. One has to be careful about the maximum height and via-connectors here .
PigletsDad
My intelligence test came back negative.
The bigger the group buy, the closer the matching of sets of 16.
For argument's sake, lets say there is a spread of +/-20% If four people buy sets, then you cannot do worse than +/-5%, and it is almost certain that you will do much better.
It is worth buying a few spares, to cope with failed devices, or ones way outside the normal range.
Somebody very patient has to measure them all, sort them into ascending order, and then pick out groups of 16 adjacent values.
For argument's sake, lets say there is a spread of +/-20% If four people buy sets, then you cannot do worse than +/-5%, and it is almost certain that you will do much better.
It is worth buying a few spares, to cope with failed devices, or ones way outside the normal range.
Somebody very patient has to measure them all, sort them into ascending order, and then pick out groups of 16 adjacent values.
Ahh, I tried Eagle once, but I didn´t learn it fast enough, so I quit again.
For this calculation we should know how closely they should be matched.
The 2SK170's are/were available on DIY Audio cheaply - around $30 for 100 if I remember, I bought a total of 150 I think for use in Salas phono stages and regulators. They only take a few seconds each to mesure with a 9v battery and a resistor, mine are taped to pieces of paper with the idss values written next to them.
I plan to build my Cen/Sen on veroboard so I can make it to the dimensions I have for the space available.
The only thing that puts me off with the Cen/Sen was the floating power supply (i.e. batteries). You then either have to fit a charging circuit in the case, fit an exernal battery pack or take the lid off and change the batteries every so-many hours. I bought four 9V PP3 rechargeables to use, and am planning to fit a switch to the rear panel to switch the supplies on and off.
What is fairly clear from reading the articles is that this is a very high performance design and I wanted to build an "ultimate" Arcam Alpha, but with everything in one case, as ever there are always compromises!
In order to thermally couple all four of them I guess you could cut a piece of aluminium or copper, drill holes for cable ties and bond all four to the heatsink, two pairs facing each other.
I plan to build my Cen/Sen on veroboard so I can make it to the dimensions I have for the space available.
The only thing that puts me off with the Cen/Sen was the floating power supply (i.e. batteries). You then either have to fit a charging circuit in the case, fit an exernal battery pack or take the lid off and change the batteries every so-many hours. I bought four 9V PP3 rechargeables to use, and am planning to fit a switch to the rear panel to switch the supplies on and off.
What is fairly clear from reading the articles is that this is a very high performance design and I wanted to build an "ultimate" Arcam Alpha, but with everything in one case, as ever there are always compromises!
In order to thermally couple all four of them I guess you could cut a piece of aluminium or copper, drill holes for cable ties and bond all four to the heatsink, two pairs facing each other.
Hi
Yes. As in two quad pairs per channel, L and R. Please note the transformer I used for Bal to SE conversion HAS to be in the preamp, not the DAC, so though excellent sounding, it's not a universal solution for SE equipment users (to find out about using transformers, see the white papers on the Jensen website). BTW Patrick uses balanced audio circuitry exclusively, and has stated he has no interest in SE circuitry
No, just different. Nic recented raised the possibility of trying CEN instead on the DIY Audio thread. Personally I'd stick with SEN for now. Both 2SK369V and 2SJ74V are obsolete types (in that they're no longer made), but the 369's are much more abundant that the 74's.
Best wishes
Paul N
Yes. As in two quad pairs per channel, L and R. Please note the transformer I used for Bal to SE conversion HAS to be in the preamp, not the DAC, so though excellent sounding, it's not a universal solution for SE equipment users (to find out about using transformers, see the white papers on the Jensen website). BTW Patrick uses balanced audio circuitry exclusively, and has stated he has no interest in SE circuitry
No, just different. Nic recented raised the possibility of trying CEN instead on the DIY Audio thread. Personally I'd stick with SEN for now. Both 2SK369V and 2SJ74V are obsolete types (in that they're no longer made), but the 369's are much more abundant that the 74's.
Best wishes
Paul N