Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: sec1rlr on April 04, 2025, 09:39:57 pm
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The mojotone kit comes with a 20,20,20,20 500v Can Capacitor with a diameter of about 1.25" and mojotone's chassis is cutout is 1.25". On the other hand I see that Hoffman uses a 40,20,20,20 Can Capacitor and it has a diameter of 1.50".
I am doing the Hoffman build, but using the Mojotone chassis and various "kit" hard parts. In the opinion of others much smarter than me, it is worth the effort to use the larger 1.5" inch Can Capacitor? This means ordering the part including the bigger clamp to mount it to the chassis and also resizing the capacitor hole cutout to support the larger diameter. Will I realistically even hear the difference?
I am not a purist and going for the original "fender" in every aspect. I'm looking to do this once and have a quality amp in the family for years to come. I'm hobbyist, non gigging guitar player if that's a factor.
Interested in learning your thoughts. I purchased the larger dia capacitor but not the clamp. I didn't realize I would need to change the chassis hole diameter. I can return the part if "the juice just isn't worth the squeeze"
Thanks, Rob
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Wich Princeton are talking about ; show schematic .
The 964 I show use four 20 mfds
You can use the fifth capacitor to double the first one at the GZ34 output . You will have 40 mfds
Or don't use it .
To resume : Keep the Mojotone cap .
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Thanks Latole for the comments.
The schematic is the one provided by the Hoffman Princeton Reverb Build. Again, I realize that many of the schematics show only the 20's in the cap capacitor including the one you pointed out, but his show's the one 40 and the rest 20's. From many on here the consensus seems to be his is an improved build vs the mojotone and I'm not certain the "true" affect the cap difference makes. If it's really "nice" to have, I'll modify the chassis and use it. If it's,... "you're never going to know... this isn't why his is better kind of thing", I'll live with the mojotone can cap.
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I think you may misunderstand Latole's comment. If you use the Mojo can and parallel two of the 20uf sections at node A, you will have the same capacitance as using the 40uf section in the other can cap. Either way you still have 3 20uf sections to use for the other nodes.
Edit - with SEL49 pointing out that the cap cans only have 4 sections, rather than 5, scratch the above.
Also, I will mention that just because the cap diameter is 1.5" does not mean that a 1.25" hole cannot be used. It depends on how much clearance there is for the connections. The can does not need to pass through the chassis, it can but up against the chassis, secured by the clamp.
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I suggest using the mojo can since you already have it, and it fits the chassis. The 40/20/20/20 would be a marginal improvement but it's unlikely that you could tell the difference. Probably the main reason Hoffman used the 40/20/20/20 is because he sells that cap and has it in stock. He doesn't sell the 20/20/20/20.
Just something to keep in mind... I prefer the Hoffman board, but you should be aware that Hoffman's board is designed using small Xicon (or Panasonic) coupling capacitors and Mojo's board is designed for large coupling caps. You will find that some of the big Mojo caps, especially the .1µF caps, will not fit nicely on the Hoffman board. Sure, you can make the large caps fit but it will not be pretty.
BTW, these cap cans only have four sections, not five as you stated in the original post.
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BTW, these cap cans only have four sections, not five as you stated in the original post.
Big difference :BangHead:
Wrong information may not help .
Mojo can caps; 4 X 20 mfds
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I think you may misunderstand Latole's comment. If you use the Mojo can and parallel two of the 20uf sections at node A, you will have the same capacitance as using the 40uf section in the other can cap. Either way you still have 3 20uf sections to use for the other nodes.
Edit - with SEL49 pointing out that the cap cans only have 4 sections, rather than 5, scratch the above.
Also, I will mention that just because the cap diameter is 1.5" does not mean that a 1.25" hole cannot be used. It depends on how much clearance there is for the connections. The can does not need to pass through the chassis, it can but up against the chassis, secured by the clamp.
Yep. Good catch, I got the number of capacitor sections wrong in the can,... there are 4 not 5. But you make an excellent point about the can not having to clear the chassis as long as the terminals themselves can safely protude. I'll have to measure that to determine if it will work or not. Again, excellent point.
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I suggest using the mojo can since you already have it, and it fits the chassis. The 40/20/20/20 would be a marginal improvement but it's unlikely that you could tell the difference. Probably the main reason Hoffman used the 40/20/20/20 is because he sells that cap and has it in stock. He doesn't sell the 20/20/20/20.
Just something to keep in mind... I prefer the Hoffman board, but you should be aware that Hoffman's board is designed using small Xicon (or Panasonic) coupling capacitors and Mojo's board is designed for large coupling caps. You will find that some of the big Mojo caps, especially the .1µF caps, will not fit nicely on the Hoffman board. Sure, you can make the large caps fit but it will not be pretty.
BTW, these cap cans only have four sections, not five as you stated in the original post.
Excellent points as well.... he sells what he has in stock as the primary driver behind the one specific can capacitor. In terms of the other board electronics, I purchased all of the Hoffman board electronics along with his board to avoid any issues as you have described. The added cost was marginal and well worth it to avoid problems. Plus now I have the Mojotone stuff to use in some possible build in the future.
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BTW, these cap cans only have four sections, not five as you stated in the original post.
Big difference :BangHead:
Wrong information may not help .
Mojo can caps; 4 X 20 mfds
You are absolutely correct. I updated the original post to reflect the correct information. Again thank you for your comments and suggestions.