Just a general comment to everyone.
The more people contribute and express some interest the quicker this will be.
I am feeling a little uncertain how much time to invest.
I am quite happy to work around the clock on this but only if you guys are interested.
Everyone that was interested please reconfirm, just so I know.
Hoping we have 10 people.
Things to do - agree on and design.
1) Back panel - IEC/Binding Posts/RCA/XLR parts. As mentioned earlier I am happy using Neutrik for all audio connections, and Schurter for the IEC, but someone else mentioned a preference for Cardas on some of the items. This could be tricky to agree on everything but where we disagree we could just get the panel pierced with a small pilot hole to make drilling holes more straight forward (ie no measuring needed to position components on the back panel).
2) Vent design for top and bottom panel - I will draw this
3) Front panel design - completely stock or added design features - ie blind bolts or exposed counter bored hex socket bolts, decorative design features, engraving etc.
4) Miscellaneous features
5) Get an idea of the interest between black or silver front panel - it might be possible to have either if we know up front the numbers.
Things completed
Heatsink UMS Pattern
Poll taken on base plate requirements
The more people contribute and express some interest the quicker this will be.
I am feeling a little uncertain how much time to invest.
I am quite happy to work around the clock on this but only if you guys are interested.
Everyone that was interested please reconfirm, just so I know.
Hoping we have 10 people.
Things to do - agree on and design.
1) Back panel - IEC/Binding Posts/RCA/XLR parts. As mentioned earlier I am happy using Neutrik for all audio connections, and Schurter for the IEC, but someone else mentioned a preference for Cardas on some of the items. This could be tricky to agree on everything but where we disagree we could just get the panel pierced with a small pilot hole to make drilling holes more straight forward (ie no measuring needed to position components on the back panel).
2) Vent design for top and bottom panel - I will draw this
3) Front panel design - completely stock or added design features - ie blind bolts or exposed counter bored hex socket bolts, decorative design features, engraving etc.
4) Miscellaneous features
5) Get an idea of the interest between black or silver front panel - it might be possible to have either if we know up front the numbers.
Things completed
Heatsink UMS Pattern
Poll taken on base plate requirements
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I see this chassis being a good solution for high-bias, 50 Watt Class A amplifiers. These begin with the 50W Schade feedback Mosfet amp with a pair of IXFN140N20P hockey pucks running at at a bias of 3.2A from a single 60V rail. The Singing Bush is two variations on this theme, and allows for lower 2.2A bias current. The SIT-3X is a fairly new animal that supports different power supply configurations from single rail to dual rail. There are also some XA25-like designs that run fairly high bias from dual rails.
All of these need larger heatsinks and plenty of room inside the chassis to build a beastly power supply. The minimum configuration would probably be a pair of 400VA transformers, with a pair of 500VA transformers being a safer bet to maintain good regulation. Alternatives would be a single 800VA or 1000VA transformer with multiple secondary windings to offer most of the benefits of a full dual-mono configuration.
A standard (450mm) width 4U aluminum chassis, with its 360mm internal width, can accommodate a pair of Antek 400VA or 500VA transformers side-by-side with little difficulty. A pair of 600VA transformers is also possible, as they are the same diameter as the 500VA offerings. Given some attention to detail, the extra depth of a 500mm floorplate offers enough room for the bridge rectifiers and bulk supply capacitors. Monolithic hockey puck style rectifiers, such as the VBE 60-06A or the VBO52-08N07 preferred by 2 pico, are a good way to go.
I'm sure a 480mm wide chassis would be more flexible regarding component and PCB placement, but it seems the 450mm width will suffice.
The next big consideration is power dissipation. With 180W or more per channel, a 4U, 500mm deep chassis is on the edge in its standard configuration. I have become accustomed to adding aluminum (aluminium?) L brackets between the bottom edge of the heatsinks and the floorplate to act as a thicker spine and transfer some heat to the base of the amp. Sometimes I add similar brackets between the rear of the sinks and the back plate for a similar effect. The thick front plate is also good for dissipating some power.
Building a large amp obviously requires a lot of planning and fine execution. But that's part of what makes this fun, right? ;-)
All of these need larger heatsinks and plenty of room inside the chassis to build a beastly power supply. The minimum configuration would probably be a pair of 400VA transformers, with a pair of 500VA transformers being a safer bet to maintain good regulation. Alternatives would be a single 800VA or 1000VA transformer with multiple secondary windings to offer most of the benefits of a full dual-mono configuration.
A standard (450mm) width 4U aluminum chassis, with its 360mm internal width, can accommodate a pair of Antek 400VA or 500VA transformers side-by-side with little difficulty. A pair of 600VA transformers is also possible, as they are the same diameter as the 500VA offerings. Given some attention to detail, the extra depth of a 500mm floorplate offers enough room for the bridge rectifiers and bulk supply capacitors. Monolithic hockey puck style rectifiers, such as the VBE 60-06A or the VBO52-08N07 preferred by 2 pico, are a good way to go.
I'm sure a 480mm wide chassis would be more flexible regarding component and PCB placement, but it seems the 450mm width will suffice.
The next big consideration is power dissipation. With 180W or more per channel, a 4U, 500mm deep chassis is on the edge in its standard configuration. I have become accustomed to adding aluminum (aluminium?) L brackets between the bottom edge of the heatsinks and the floorplate to act as a thicker spine and transfer some heat to the base of the amp. Sometimes I add similar brackets between the rear of the sinks and the back plate for a similar effect. The thick front plate is also good for dissipating some power.
Building a large amp obviously requires a lot of planning and fine execution. But that's part of what makes this fun, right? ;-)
This looks like a good top / bottom panel design. If anything, I might extend the column of slots next to the outside ones down the full depth of the plate as well.
Looking great so far IMO.
Does the bottom plate have any cooling slots? If not, it might might be a good idea to add some that match the slots on the top plate if possible while still maintaining the structural rigidity.
I think it would significantly increase convective airflow/cooling through inside of the chassis.
Just an idea, if other people want it though, as I'm still not able to commit to buy one of these for now.
Does the bottom plate have any cooling slots? If not, it might might be a good idea to add some that match the slots on the top plate if possible while still maintaining the structural rigidity.
I think it would significantly increase convective airflow/cooling through inside of the chassis.
Just an idea, if other people want it though, as I'm still not able to commit to buy one of these for now.
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Audio Connections for Back Panel
Just throwing out some details of Neutrik connectors.
I tend to like Neutrik, cause it is excellent quality at a reasonable price.
Please share if you have other preferences.
RCA
NF2D-B-9 | Neutrik
https://www.neutrik.com/en/neutrik/products/phono-rca-connectors/phono-rca-chassis-connectors
XLR
NC3FD-LX-B | Neutrik
NC3MD-LX-B | Neutrik
Speaker
NLT4MP-BAG | Neutrik
If we can agree on some items then it will make mounting them on the back panel easy.
Just throwing out some details of Neutrik connectors.
I tend to like Neutrik, cause it is excellent quality at a reasonable price.
Please share if you have other preferences.
RCA
NF2D-B-9 | Neutrik
https://www.neutrik.com/en/neutrik/products/phono-rca-connectors/phono-rca-chassis-connectors
XLR
NC3FD-LX-B | Neutrik
NC3MD-LX-B | Neutrik
Speaker
NLT4MP-BAG | Neutrik
If we can agree on some items then it will make mounting them on the back panel easy.
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I like all the Neutrik connectors except for the four-pole speaker ones. While I have and prefer the Neutrik Speak-On connectors for musical instrument amplifiers, they don't fit well with most home audio speaker cables.
For high resolution audio, I prefer robust 5-way binding posts, such as these:
ConneX Single Binding Posts (Oversized) 5-Way
For high resolution audio, I prefer robust 5-way binding posts, such as these:
ConneX Single Binding Posts (Oversized) 5-Way
I use internal bi-wire speaker cables to drive my old Vandersteen 2C speakers. If the group decides to go with the Neutrik speaker connectors, then I will have to try some of the Canare Star Quad cable. The cables I'm currently using are AudioQuest Bedrock with banana connectors on each end.