Spoon109, congratulations on your progress! Thrilled to see you've decided to try three different input stage daughter cards: Ishikawa, Mountain View, Tucson thruhole.
Also congratulations on your bravery to use an SMD-to-DIP8 adapter card! That's not something a complete rookie would have dreamed up.
Also congratulations on your bravery to use an SMD-to-DIP8 adapter card! That's not something a complete rookie would have dreamed up.
I remember a term from music lessons years ago: "da capo al fine", from beginning to end which also applies to reading this thread. Or as Mark Johnson's close personal friend Francis Bacon wrote in 1602: "Read to weigh and consider."
Nelson Pass's original post "Official M2 schematic" has info as well as Tea-Bags "GB Pass M2 Clone Boards with 120mm UMS spacing by Tea-Bag".
Nelson Pass's original post "Official M2 schematic" has info as well as Tea-Bags "GB Pass M2 Clone Boards with 120mm UMS spacing by Tea-Bag".
Regarding the power transformer, I believe our builders will save some time and effort by choosing one with built-in electrostatic shielding and a magnetic shield band, such as the Antek AS-4218. It is also important to include the 400VA steel case for this toroid. I used a 400mm deep chasis which allowed the transformer to be bolted to the base plate near the front of the amp, and had plenty of room for the diyAudio universal PSU board. I have had no issues with hum.
I believe 6L6 used the Modushop deluxe 4U chassis, which is 300mm deep. In this case I would recommend bolting the transformer to the inside of the 10mm thick front plate. This allows greater physical separation from the Edcor signal transformers, and appears to be a favorable orientation to reduce magnetic interaction.
I believe 6L6 used the Modushop deluxe 4U chassis, which is 300mm deep. In this case I would recommend bolting the transformer to the inside of the 10mm thick front plate. This allows greater physical separation from the Edcor signal transformers, and appears to be a favorable orientation to reduce magnetic interaction.
My M2X build is progressing slowly with build of 2 x universal PSUs (I build mono blocks) and the plan is to add a RC link using Jensen 4-pole caps. I use the large 5U chassis so plenty of room inside…..so why not have some fun? 
A Jensen white paper on 4-pole caps for those interested:
http://jensencapacitors.com/CustomerData/Files/Folders/4-pdf/5_4pole.pdf
A Jensen white paper on 4-pole caps for those interested:
http://jensencapacitors.com/CustomerData/Files/Folders/4-pdf/5_4pole.pdf
Attachments
Does First Watt use those four terminal capacitors in any of its currently shipping products? (SIT-1, SIT-2, SIT-3, J2, F6, F7)
I've used their great grandfathers, called "feedthrough caps", which have been around since vacuum tube radio transmitters. You can buy them today from more than one manufacturer, at Mouser.com (LINK) . I install them in power supply "super regulators", to squelch that last little ooch of noise off the sensitive VREF node.
I've used their great grandfathers, called "feedthrough caps", which have been around since vacuum tube radio transmitters. You can buy them today from more than one manufacturer, at Mouser.com (LINK) . I install them in power supply "super regulators", to squelch that last little ooch of noise off the sensitive VREF node.
I have not seen the 4-pole used anywhere but I know Jensen sell a few each year so someone are probably using them. The link at Mouser are to caps which are rather small?
The Jensen at the picture are quite large (8200 uF / 63 VDC). The plan is to use them as the last link in the CRCRC chain. CRC from universal PSU PCB and then the extra RC using 4-Pole as the "C". Just to see how low I can get ripple/noise…..even that I know it is not necessary….and that M2X amp has very good ripple rejection.
^ Be mindful of the current rating of those Jensen 4-pole caps. They are true feed-through in the sense that the full power supply current is conducted through the 'plates' of the capacitor. Current rating is a function of the diameter of the capacitor, as the only way to increase current capacity is by increasing the area of the plates.
I remember reading an account of someone who tried these in a high current amplifier, and found that the Jensens got very hot and started to smell bad after just a couple minutes of operation.
I remember reading an account of someone who tried these in a high current amplifier, and found that the Jensens got very hot and started to smell bad after just a couple minutes of operation.
Ok.....I will check the current limitation. I will have two in parallel for each MX2 board (so four pr. board.....two for +24VDC and two for -24VDC) And if last in chain the ripple current will be very small. It is almost DC at that stage so assume that current draw is almost bias current…..so less than 2A?
I was assuming that these 4-poles could take "some" current…….
I was assuming that these 4-poles could take "some" current…….
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It is the DC current rating to watch with these caps. This is a case where the constant bias current of a Class A amplifier makes component selection more difficult. Having two of the Jensens in parallel will help with the current handling, provided that the current is evenly distributed between the two.
This is from a Jensen app note:
This is from a Jensen app note:
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Ok.....I think that requirement is fulfilled…..current to/from the caps. According to web they are rated for "high current":
4 Pole axial electrolytic capacitor
I have asked for a data sheet……..
4 Pole axial electrolytic capacitor
I have asked for a data sheet……..
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Tuscon SMD - Listening Impressions
I have been living with the Tuscon IPS in my M2x for over a week now. I can understand why some have not felt the need to try other daughterboards after this one. Mine was built with an OPA1611 and a Nichicon FW series 220 uF, 63V bypass cap between VPOS and VNEG. Due to the low input offset voltage of the opamp, I felt safe eliminating the output coupling cap.
My initial impression was that this reminded me of the Ishikawa IPS that I built with a matched pair of Linear Systems JFets. The sound is very fast, clean and detailed. The tonal balance and soundstaging is more forward than either the Ishikawa or Mtn View, and also somewhat wider. The reproduced dynamics of recordings with strong percussion instruments are really quite amazing. With these attributes, the Tuscon SMD can also be merciless with less than great recordings. While hearing a little hum from the electric guitar amplifier used in the studio can be enjoyable, hearing a misbehaving rack-mount compressor with ancient tubes and leaky electrolytics is somewhat less so. Don't get me started on the abominable electronic drum kits that were all the rage in the 80s.
The OPA1611 has an excellent PSRR, and together with the local power supply bypass, I suspect this may be a primary contributor to the more forward and detailed imaging. It would also seem that the Mtn View and Tucson both enjoy the advantage of local power supply bypassing, while the Ishikawa does not. Perhaps in the future a new version of Ishikawa could be made to include the option of a 220 uF or 470 uF cap between VPOS and VNEG. Maybe even include a spot for a 470 nF film bypass cap. I have a veroboard version of Ishikawa waiting to test that thought, along with several other IPS ideas queued up while I'm working on a more robust means of using the mounting holes as electrical connections.
I have been living with the Tuscon IPS in my M2x for over a week now. I can understand why some have not felt the need to try other daughterboards after this one. Mine was built with an OPA1611 and a Nichicon FW series 220 uF, 63V bypass cap between VPOS and VNEG. Due to the low input offset voltage of the opamp, I felt safe eliminating the output coupling cap.
My initial impression was that this reminded me of the Ishikawa IPS that I built with a matched pair of Linear Systems JFets. The sound is very fast, clean and detailed. The tonal balance and soundstaging is more forward than either the Ishikawa or Mtn View, and also somewhat wider. The reproduced dynamics of recordings with strong percussion instruments are really quite amazing. With these attributes, the Tuscon SMD can also be merciless with less than great recordings. While hearing a little hum from the electric guitar amplifier used in the studio can be enjoyable, hearing a misbehaving rack-mount compressor with ancient tubes and leaky electrolytics is somewhat less so. Don't get me started on the abominable electronic drum kits that were all the rage in the 80s.
The OPA1611 has an excellent PSRR, and together with the local power supply bypass, I suspect this may be a primary contributor to the more forward and detailed imaging. It would also seem that the Mtn View and Tucson both enjoy the advantage of local power supply bypassing, while the Ishikawa does not. Perhaps in the future a new version of Ishikawa could be made to include the option of a 220 uF or 470 uF cap between VPOS and VNEG. Maybe even include a spot for a 470 nF film bypass cap. I have a veroboard version of Ishikawa waiting to test that thought, along with several other IPS ideas queued up while I'm working on a more robust means of using the mounting holes as electrical connections.
I've enjoyed my time with the Tuscon as well. Since this was the first daughterboard I tried my only basis for comparison was with the ACA and other amps I've owned. The M2x /Tuscon bettered all of them. I listen primarily for tone. Soundstaging, detail and pace are all important but it's tone that always gets my attention first. For example, I know what a flugelhorn should sound like. In the hands of a master like Freddie Hubbard it has a cloudy, brassy tone that almost sounds muted in comparison to an open trumpet. In my hands, well, something much, much less, Still, I know how it's supposed to sound. The M2x/Tuscon got it right. So right, in fact, that I nearly stopped at that point.
However, that would have flown in the face of a primary reason for choosing this build. So I installed the Mountain View. As good as the Tuscon is, I liked the Mountain View even more. I found the sound to be more organic, more natural. I found it to be warmer, which for me is a desired quality. A seven hour listening session with multiple sources revealed no trace of listening fatigue at all. So again I'm thinking I've reached a stopping point. We'll see. Those other boards beckon but I'm very pleased with what I have.
However, that would have flown in the face of a primary reason for choosing this build. So I installed the Mountain View. As good as the Tuscon is, I liked the Mountain View even more. I found the sound to be more organic, more natural. I found it to be warmer, which for me is a desired quality. A seven hour listening session with multiple sources revealed no trace of listening fatigue at all. So again I'm thinking I've reached a stopping point. We'll see. Those other boards beckon but I'm very pleased with what I have.