More premium/upscale parts for JTM45+ build

[asd123asd234sdrf]

Hi all,

I am parting out some upgrades for my planned build of the Tube Depot JTM45+. I am looking to upgrade parts here and there, mainly the caps and resistors. I think I have settled on PRP 1W resistors for all positions needing 1W or less. I'm still uncertain on what brands are considered "high end" for larger 3W resistors. I know there's lots of debate on resistor materials, carbon comp vs film, metal oxide, etc. I've been saving for a while and have the budget to get nice high end parts, so I want to use it. So any suggestions on the larger power resistors if you were to go as nice as you can? I'm not talking $10+ per part, but a couple bucks each would be fine.

For caps, I've settled on F&T for filter caps, and probably Sprague Atoms for the electrolytics. Sozo NextGen Yellow Mustards for coupling caps. Are there any other brands/models I should check out?

Alpha pots are solid, maybe I'll consider CTS if they have the right size and value, but not too concerned about them.

I'll get NOS tubes at some point, but that will be a different (big!) budget bucket Same with transformers probably, stick with stock and maybe upgrade down the road if I feel like it.

Carling switches are solid, I'm looking at using Cliff jacks as well. Not sure on tube sockets, the included Beltons seem nice.

Any suggestions on other parts or brands I might be missing? I'm not shooting for 100% vintage NOS specs, just want it to sound good. I also just like tinkering and can't leave well enough alone, hence swapping out parts in full kit I get this is not the most efficient way to do all this, but I'll have fun, and that is the point for me.

Thanks in advance for any input!

 

[Matthews Guitars]

EBY TS103 9 pin tube sockets are what I would recommend for the preamp sockets, as they are one of a few "correct" types and their quality is excellent. They will last 50 years or more. I'd also recommend ceramic Amphenol snap ring mount octal tube sockets, as they are essentially forever parts.

 

[asd123asd234sdrf]

Thanks @Matthews Guitars . I wasn't aware of either, so I will check those both out.

 

[asd123asd234sdrf]

Thank you eBay, scored some of both lol.

 

[stickyfinger]

EBY TS103 9 pin tube sockets are what I would recommend for the preamp sockets, as they are one of a few "correct" types and their quality is excellent. They will last 50 years or more. I'd also recommend ceramic Amphenol snap ring mount octal tube sockets, as they are essentially forever parts.

Plastic white Cinch were the correct ones for most of the 60s early 70s and black Cinch for the rest of the 70s early 80s. They were probably the cheapest sockets they could buy cause the weren't engraved with any marking (TS103 ect) as far as Im aware. What amps had EBY TS103?

Upgrading to good 9 pin sockets is a good idea as i find modern ones are too tight. Make sure NOS ones are clean and the pins arnt black.

Other than that I probably wouldn't spend any more money upgrading a cheap kit. It will sound fine the way it is. if you enjoy building the amp and want to build another Valvestorm kits are the way to go.

 

[playloud]

I think those resistors are overkill. The originals were built with carbon film and comp resistors - not a metal film in sight - and people seem to like the sound

There was an era of clone building (90s?) where people tried to "improve" the classics with higher spec parts (boutique hifi metal film resistors, orange drop caps etc.) and the results were disappointing. There was an era after that (early 2000s) where PEC pots were in vogue, but once people realized they couldn't be cleaned, they fell out of favor too.

The Sozo "mustards" are marketing nonsense really. Either use Mallory 150s or get original mustards (0.1uf can still be found cheaply at least - actually about the same price as the Sozos!)

I would prioritize the transformer selection, as those are the most expensive parts - both in terms of unit price and shipping. "Buy right, buy once" etc.

 

[Matthews Guitars]

I've seen TS103s in later, 70s Marshalls, and they are good quality, fit right up to the original hole patterns, and use "correct" style tube covers. I favor them and use them any time I need to put a new socket in, whether on an old amp or a new build.

 

[asd123asd234sdrf]

I think those resistors are overkill.

That's part of the fun I know I'm less than sane doing things this way, but it's fun and that's enough for me. What carbon comp or carbon film would you go with for a new build with cost as no object?

 

[playloud]

That's part of the fun I know I'm less than sane doing things this way, but it's fun and that's enough for me. What carbon comp or carbon film would you go with for a new build with cost as no object?

I'd use original Piher/Hystab/AB.

Perhaps "overkill" was the wrong word. What I meant is that you'll overshoot the target - i.e. you'll probably find bog standard carbon film resistors (with their looser tolerance/higher noise floor) produce a more pleasing outcome).

 

[asd123asd234sdrf]

I'd use original Piher/Hystab/AB.

This just seems very time consuming and expensive compared to using something currently in production. Do you use ebay or other auction sites to source all the values and then sort through for proper values? I can't see how else it could be done.

 

[playloud]

This just seems very time consuming and expensive compared to using something currently in production. Do you use ebay or other auction sites to source all the values and then sort through for proper values? I can't see how else it could be done.

There was a user on here selling sets of Piher resistors recently. Check the classifieds section.

I got most of the Pihers for my JTM 45/100 from a single Ebay seller. PM me if you want his email address.

Honestly, though, any 1/2W carbon film resistors should be fine for this build (maybe use carbon comp for HT dropping resistors). I would only start worrying about metal film for higher gain circuits where noise/oscillation is a serious concern.

 

[Pete Farrington]

I think I have settled on PRP 1W resistors for all positions needing 1W or less

The manufacturer info looks to be stinking heap of meaningless, unquantifiable BS hyperbole to me https://www.partsconnexion.com/media/pdfs/prp.pdf

 

[Benny]

Hi all,

I am parting out some upgrades for my planned build of the Tube Depot JTM45+. I am looking to upgrade parts here and there, mainly the caps and resistors. I think I have settled on PRP 1W resistors for all positions needing 1W or less. I'm still uncertain on what brands are considered "high end" for larger 3W resistors. I know there's lots of debate on resistor materials, carbon comp vs film, metal oxide, etc. I've been saving for a while and have the budget to get nice high end parts, so I want to use it. So any suggestions on the larger power resistors if you were to go as nice as you can? I'm not talking $10+ per part, but a couple bucks each would be fine.

For caps, I've settled on F&T for filter caps, and probably Sprague Atoms for the electrolytics. Sozo NextGen Yellow Mustards for coupling caps. Are there any other brands/models I should check out?

Alpha pots are solid, maybe I'll consider CTS if they have the right size and value, but not too concerned about them.

I'll get NOS tubes at some point, but that will be a different (big!) budget bucket Same with transformers probably, stick with stock and maybe upgrade down the road if I feel like it.

Carling switches are solid, I'm looking at using Cliff jacks as well. Not sure on tube sockets, the included Beltons seem nice.

Any suggestions on other parts or brands I might be missing? I'm not shooting for 100% vintage NOS specs, just want it to sound good. I also just like tinkering and can't leave well enough alone, hence swapping out parts in full kit I get this is not the most efficient way to do all this, but I'll have fun, and that is the point for me.

Thanks in advance for any input!

I have built 5 or 6 amps and each time tried to experiemnt with parts. Even the wire, transformers, caps, resistors. For capacitors (at least the "tone caps" ) I have, tried 2 generations of sozo, TADs, and then some others like orange drop. There is one cap that I really liked and it was a French made cap; Solen "fast caps". Overall, you have to have fairly special ears and a favourable listing with the gods of chance to find a significant difference one way or the other. The benefit to using close tolerance components is that you know within a smaller margin what values you installed. So if you are are knowledgeable enough to tweak some values then you have better resolution for fine tuning. Caps wear in. Some fail. The only cap I ever had fail was one Sozo cap. Reliablity can be important too.

but ...
I once built the same circuit in two different amps with all different components (not very scientific). The amps sounded completely different. The second one with "botique" components was so bottom heavy that I hated it and I was so disgusted that I sold them both. Due to lack of scientific rigor I have no idea what was causing the difference. So there you go. I might have made a mistake somewhere, but I could not find it. Gods of chance at work. Good luck.

 

[asd123asd234sdrf]

The manufacturer info looks to be stinking heap of meaningless, unquantifiable BS hyperbole to me https://www.partsconnexion.com/media/pdfs/prp.pdf

I saw 1W and 500V, and that was what sold me. The rest is... interesting, to say the least lol. Being a cool red color doesn't hurt at all either!

 

[playloud]

The manufacturer info looks to be stinking heap of meaningless, unquantifiable BS hyperbole to me https://www.partsconnexion.com/media/pdfs/prp.pdf

The secret is only being "available in small quantities". Even a medium production run can make the tone escape faster than Wile E Coyote!

 

[Pete Farrington]

Well done for checking the resistor voltage rating

 

[2L man]

I Think Spraque Atoms have very poor VFM. I understand if someone want to have as large replacement capacitor case as original "to look right" then a stuffed tube is OK. Spraques I have bought have only +75C temp rating and when no hour rating is listed it can be only 1500h.

100V and higher voltage F/T temp rating is +85C but I recall I have not found their life rating neither.

Unfortunately Axial electrolyte selection is low.

When I build Circuit Board myself I use Radial electrolytes. They come few different dimensions and huge vatiety of specs but bigger diameter ones are shorter and I just drill a hole to the CB and install them wires pointing up.

Nichicon and Panasonic high end electrolyte are +105C and 10 000h or 12 000h and cost perhaps only 1/3 what Axials when buying more, 20 and up.

However their internal resistance is very low which mean that they can deliver high peak current but it also mean they take high peak current when they charge. When Solid State rectifier diodes are used this tends to strengthen PT Electromagnetic Stray Field which then can interact with OT. Installing current limiter resistor(s) drop bighest peaks away when they kind of make electrolyte internal charge resistance higher.

Tube rectifier peak current has a limit and installing current limiter resistors to both anode circuits drop the current peaks.

 

[PelliX]

So if you are are knowledgeable enough to tweak some values then you have better resolution for fine tuning. Caps wear in. Some fail. The only cap I ever had fail was one Sozo cap. Reliablity can be important too.

Time for an ESR meter...

 

[Pete Farrington]

Spraque Atoms have very poor VFM. I understand if someone want to have as large replacement capacitor case

The Sprague TVA caps usually used for cathode bypass don’t tend to have the over sized, mock vintage case that the high voltage ones do.

Spraques I have bought have only +75C temp rating and when no hour rating is listed it can be only 1500h

Below 500V, the TVA range is 85°C, 500V is a pathetic 65°C.

https://www.vishay.com/docs/42038/tvatom.pdf

Can’t recall the brand, but I’ve seen some ecaps life of only 1000hours.
Bear in mind that’s at full voltage AND temperature; as either / both reduce, life increases.

 

[neikeel]

I don't use Sprague Atoms - too many duff ones.
For the small caps (cathode and bias) I quite like the RIFAs if you can find the right size and spec. or the Vishay BCs
YMMV