Very good, just what we are looking for. If any other issues are caught, please post here.
Both noted Patrick. Will make the changes with the next revision.
Thanks again,
Dave
I have been asked by PM about the protection board BoM, jumper connections, and test procedures.
As you all known, while the schematics originated from me, the PCB was done by ashaw.
I believe he has already published the B0M here :
http://www.diyaudio.com/forums/group-buys/205531-potential-group-buy-f5x-components.html
I have been promised by email that jumper connections and test procedures will follow in two weeks.
But of course I can only rely on the good will of people involved in this project.
So hopefully you will all be informed in due course.
Patrick
As you all known, while the schematics originated from me, the PCB was done by ashaw.
I believe he has already published the B0M here :
http://www.diyaudio.com/forums/group-buys/205531-potential-group-buy-f5x-components.html
I have been promised by email that jumper connections and test procedures will follow in two weeks.
But of course I can only rely on the good will of people involved in this project.
So hopefully you will all be informed in due course.
Patrick
You can also find this BOM in posting #661 of the "EUVL approach" thread and interestingly also in the next posting.
But there is something wrong with this BOM. Digikey # 455-4105-1-ND in the third row of the BOM, said to be a "Ceramic 1.0uF Capacitor -1206, 50V, X7R", doesn't exist. In fact, you can do a Google search using this number and nothing will be picked up.
OK. In the corresponding GB for the protection kit Digikey # 399-1249-1-ND is given for this 1uF cap, also in the third position. But this Digikey number refers to a 0.1 uF/50 V cap:
Capacitors | Ceramic Capacitors | DigiKey
ashaw, are you sure that you bought and distributed the correct value?Which version of the power supply BOM are you referring to? I have the impression that in the version I was considering (the one attached to posting #39 of this thread), these early errors are already corrected. In this BOM, STTH2002D is used as rectifier diode.
Anyway, I noted another discrepancy between the BOM in posting #39 and the schematics shown in posting #706 of the "EUVL approach" thread:
The power supply BOM calls for a 24V Omron relay (G6S-2; Digikey # Z2608-ND) on the regulator boards, whereas 12V relays are depicted in the schematics. Although the relay coils are attached to a 24V line on the protection board, use of the 12V version seems appropriate since they are hooked up in series and not in parallel.
In accordance with this, ashaw has ordered the 12V version of G6S-2 (Digikey # Z2607-ND) in his GB.
STTH2002D is what I use. MUR1520 is equivalent.
You can use both 12V and 24V relays, depending on what you can get.
The protection board has 24V supply for the replays.
But I personally like the relays to switch on and off simultaneously.
As such I wire the relays of the left and right channel in series, so 2x12V = 24V.
But you can also use 24V relays and wire them in parallel.
So the 12V relays in Alexis BoM is not a mistake.
Just inconsistency when multiple people are working on the same thing over a long period of time.
(I shall never do a project this way again.)
Technically there is no real difference.
Just personally preferences.
Patrick
You can use both 12V and 24V relays, depending on what you can get.
The protection board has 24V supply for the replays.
But I personally like the relays to switch on and off simultaneously.
As such I wire the relays of the left and right channel in series, so 2x12V = 24V.
But you can also use 24V relays and wire them in parallel.
So the 12V relays in Alexis BoM is not a mistake.
Just inconsistency when multiple people are working on the same thing over a long period of time.
(I shall never do a project this way again.)
Technically there is no real difference.
Just personally preferences.
Patrick
Ok. I finally found the components and time to finish the amp boards
I did not encounter any problems except for an initial error in not mounting the cascode jumpers with the end result of no current flowing.
I measured the front end bias and get 4.4 mA +/- 1.5% for the 8 measurement points. I will have to see where this fall within the traces for my 170/74 devices, but I think I can be reasonably satisfied with the tolerance.
I would have liked to play with the output device biasing, but I don't have any MOSFETs to play with yet (they are still with Gerhard) so that will have to wait a bit more.
I have a few questions:
can I install the mute board without having to worry (for the moment) about powering it. I.e. is it muted or un-muted when not powered?
For the control board more people have asked me about if the HJ4002 chips (supplied) are equivalent to the 74HC4002 (in the BOM). Personally I have assumed so and have already soldered these in...
A comment from ashaw would be very welcome.....
I still have to sort out the distribution issue I have had with the small parts. I will make sure everybody will have what they need and paid for. It is not really very urgent as the parts in question are mostly for the PSU regulator boards. These regulator boards are however of no use right now as we don't have the heat-sinks for them. Any plans for these Patrick? Personally I would like to place an order for these.
Cheers,
Nic
I did not encounter any problems except for an initial error in not mounting the cascode jumpers with the end result of no current flowing.
I measured the front end bias and get 4.4 mA +/- 1.5% for the 8 measurement points. I will have to see where this fall within the traces for my 170/74 devices, but I think I can be reasonably satisfied with the tolerance.
I would have liked to play with the output device biasing, but I don't have any MOSFETs to play with yet (they are still with Gerhard) so that will have to wait a bit more.
I have a few questions:
can I install the mute board without having to worry (for the moment) about powering it. I.e. is it muted or un-muted when not powered?
For the control board more people have asked me about if the HJ4002 chips (supplied) are equivalent to the 74HC4002 (in the BOM). Personally I have assumed so and have already soldered these in...
A comment from ashaw would be very welcome.....
I still have to sort out the distribution issue I have had with the small parts. I will make sure everybody will have what they need and paid for. It is not really very urgent as the parts in question are mostly for the PSU regulator boards. These regulator boards are however of no use right now as we don't have the heat-sinks for them. Any plans for these Patrick? Personally I would like to place an order for these.
Cheers,
Nic
> is it muted or un-muted when not powered?
As with all properly designed protection circuits, the passive state (no power) is the safe state.
i.e. muted.
Protection board you need to ask Alexis.
For the regulator, I am still hoping the Uwe will test the regulators. He has all components.
However if you also volunteer to test, and soon, contact WK to arrange a set of mechanical hardware to be sent to you.
Best to contact him by email.
Patrick
As with all properly designed protection circuits, the passive state (no power) is the safe state.
i.e. muted.
Protection board you need to ask Alexis.
For the regulator, I am still hoping the Uwe will test the regulators. He has all components.
However if you also volunteer to test, and soon, contact WK to arrange a set of mechanical hardware to be sent to you.
Best to contact him by email.
Patrick
>As with all properly designed protection circuits, the passive state (no power) is the safe state. i.e. muted.
That was what I reasoned.
>However if you also volunteer to test, and soon, contact WK to arrange a set of mechanical hardware to be sent to you. Best to contact him by email.
WK has e-mail. I should have the time in January/February to test.
No comments on my front-end bias? Just curious.
Cheers,
Nic
That was what I reasoned.
>However if you also volunteer to test, and soon, contact WK to arrange a set of mechanical hardware to be sent to you. Best to contact him by email.
WK has e-mail. I should have the time in January/February to test.
No comments on my front-end bias? Just curious.
Cheers,
Nic
Two minor errors/additions in the BOM:
- R45, R46 (Susumu 0805 SMD, 5.1 R): The BOM claims four of these per channel, but in the schematics and on the board, there are only two.
I assume these two would go to the two small, unlabeled and asymmetrically located SMD pads on the back of the board near the JFETs/cascode elements. Correct?
- You might want to add the "-Y"-suffix to the "MFG PN" column for the power MOSFETs.
- R45, R46 (Susumu 0805 SMD, 5.1 R): The BOM claims four of these per channel, but in the schematics and on the board, there are only two.
I assume these two would go to the two small, unlabeled and asymmetrically located SMD pads on the back of the board near the JFETs/cascode elements. Correct?
- You might want to add the "-Y"-suffix to the "MFG PN" column for the power MOSFETs.
> You could have checked by just measuring the Id of each JFET with 10R degen.
I could indeed have, especially if I knew that I ought to.
Is there a "sweet-spot" to aim for?
Should I just leave it or would I be better of fixing the problem in some way?
I guess I could easily lower the 11R triplets with some parallel (matched) resistance (mounted on the underside of the PCB), but I'm not sure if this is the way to go.
Anybody else measured these currents?
I could indeed have, especially if I knew that I ought to.
Is there a "sweet-spot" to aim for?
Should I just leave it or would I be better of fixing the problem in some way?
I guess I could easily lower the 11R triplets with some parallel (matched) resistance (mounted on the underside of the PCB), but I'm not sure if this is the way to go.
Anybody else measured these currents?
Hi Nick,
The Idss of the sets I put together came in at 6.8mA for the K170s and 7.8mA for the J74s. The front end current measured for these is ~4.8mA in circuit. See the chart here for ballpark targets for Idss and Rdegen based on calculations from the datasheets.
If your J74s and K170s in each set are the same Idss I don't think you will want to use the 5R1 degen resistor that is mounted on the bottom of the amp board. Substitute a zero ohm or small wire there. This resistor serves to more closely match the gain curves of the J74s to that of the K170s but only when the J74s are selected with higher Idss as described in the post/chart linked above.
Dave
The Idss of the sets I put together came in at 6.8mA for the K170s and 7.8mA for the J74s. The front end current measured for these is ~4.8mA in circuit. See the chart here for ballpark targets for Idss and Rdegen based on calculations from the datasheets.
If your J74s and K170s in each set are the same Idss I don't think you will want to use the 5R1 degen resistor that is mounted on the bottom of the amp board. Substitute a zero ohm or small wire there. This resistor serves to more closely match the gain curves of the J74s to that of the K170s but only when the J74s are selected with higher Idss as described in the post/chart linked above.
Dave
My 7.9 mA device Idss is for both the K170, and the J74 (after degeneration with appropriate Rdeg).
You get 4.8 mA front-end bias with 6.8 mA device Idss, while I get 4.4 mA with 7.9 mA device Idss. Any explanations come to mind
Anyway, maybe my 4.4 mA front-end bias is just fine.... I just don't know what to go for.
You get 4.8 mA front-end bias with 6.8 mA device Idss, while I get 4.4 mA with 7.9 mA device Idss. Any explanations come to mind
Anyway, maybe my 4.4 mA front-end bias is just fine.... I just don't know what to go for.
My 7.9 mA device Idss is for both the K170, and the J74 (after degeneration with appropriate Rdeg).
You get 4.8 mA front-end bias with 6.8 mA device Idss, while I get 4.4 mA with 7.9 mA device Idss. Any explanations come to mind
Anyway, maybe my 4.4 mA front-end bias is just fine.... I just don't know what to go for.
Inputs to the AMP/JFETs grounded? Otherwise I don't know. Best match for me was using 4R for degen - so my JFETs were lower than datasheet typical numbers for gain. What are you using for Rdegen and do all four corners measure the same bias current?
Dave