Build Log - #102 - So it Begins

[PicknStrum]

So, I've fallen down a bit of a rabbit hole on NOS parts. Since I'm going with the Draloric resistors, I decided to try to keep the caps as close to the originals as I can. In reading some older posts, 6PS orange drops seem to be the way to go, with 418P being similar (???). In ordering from Tubes and More, I can get most of the caps I need in either 6PS or 418P. They are out of .01. Sounds like 6PS is no longer manufactured.

I did buy caps listed as 220p .01 (6PSS10) orange drops on ebay - hope I didn't get sucked into a scam. They listed 6PS on the cap as well...I also decided to grab a .047 6PSS47 from another dealer on ebay, since Tubes and More doesn't list .047 in 6PS/418P. So as long as these are legit, I'm set there.

My question is, for the cap that couples the grid to the plate between the 2-sets of 10M resistors on V1B, can I use a .05 in that spot? Does the signal go through that cap? Tubes and More doesn't have a .047 in 6PS or 418P, which is why I grabbed the one that couples V1B to the rest of the circuit (OD preamp vs. power amp). Any thoughts here. After this, I think I'm set from an "original parts" standpoint.

[Charlie Wilson]

You should be ok with the capacitors your ordered. One .01 is for the OD and the other is your mid cap. You may want to play around with different type caps for the mid cap but that will come later. The .05 is fine as a sub for .047. That along with the 10 meg resistors are going to be your local negative feedback on V1. The real rabbit hole begins after you build the amp.
CW

[talbany]

From my understanding the 418's are basically a modern day 6PS SBE soundwise. The 220P's (If these are the older versions) A Poly and paper impregnated sort of a an upgraded version of a Bumblebee style. Paper caps have a slightly darker flatter sound vs the newer PS SBE's and take on more of a boxy vintage like tone (For lack of a better word) and can IMO also alter the character of the breakup. The 220's are a great way to tame or slightly scoop the mids. I will sometimes use these caps in the OD section or for the PI entrance. (BTW Don't expect a big change in tone by throwing in a few of these caps It's a subtle but noticeable thing IMO)..As far as the Mid cap goes some people prefer the brighter sounding mid clarity of the Polypropylene 417's in the mid spot (ala 102)to help brighten the amp up a bit (especially in the high plate amps w/NFB V1). I call them the silver Mica of mid caps. Some people like that sound and others do not. I generally recommend building the thing with the PS mid cap 1st and if you want brighter mids then swap it out. Also make sure you orient the caps correctly for noise abatement.

I am giving away all my secrets

Tony

[PicknStrum]

Sounds good guys. So I'll stick with the .05 cap for the LNFB on V1 and use the 220p 6PS on the board. Sounds like it's something that I may end up changing down the road, depending on how the amp comes out. If / when that happens, I'll defer back to you guys!


...or should I throw the 418P .05 in the mid cap spot and use the 220P .047 in the V1 LNFB? So much to ponder.

[talbany]

or should I throw the 418P .05 in the mid cap spot and use the 220P .047 in the V1 LNFB? So much to ponder.

Not sure there will be that big of a difference,however, I have not experimented with both of those caps in the FB spot.
I would use the 418 as the mid cap since that one has the biggest impact on the sound of the amp,so I would stick to the recipe on the mid cap...I use the 220P's to help shape the sound of a particular section of the pre amp (which for me was primarily the OD section) and possibly the entrance to the PI depending on how the amp responds overall after I build it and play it..

BTW. My explanation of the 220's was just to give you a general idea of what they sound like vs the newer PS6 caps..IMHO there is no better or worse here so you and others reading this can ultimately decide which cap to use or try either cap that best suits your ears

Tony

[PicknStrum]

Done - 418P in the mid spot it is.

One other thing I should've mentioned in my last post is I received the Dralorics from Jelle. There were some different values than I was expecting (most very very close) but he gave me a great explanation on all of the resistors I was confused about. He's a really awesome guy.

One thing I didn't get a ton of clarification on (and I'm hoping to get here) is with V1 LNFB section. The layouts here show two pairs of 10M resistors in series on each side of the .047 cap. Jelle told me he was unable to get 10M's but some of the Dumble's he's looked at use single 22M's on each side of the resistor instead of the pair of 10M's so he advised me to do the same. I absolutely trust is expertise - I'm just curious why this substitution works. Is this just a matter of the value not being super important in that spot? Or is there something going on with voltage that would match two 10Ms?

[dbharris]

...One thing I didn't get a ton of clarification on (and I'm hoping to get here) is with V1 LNFB section. The layouts here show two pairs of 10M resistors in series on each side of the .047 cap. Jelle told me he was unable to get 10M's but some of the Dumble's he's looked at use single 22M's on each side of the resistor instead of the pair of 10M's so he advised me to do the same. I absolutely trust is expertise - I'm just curious why this substitution works. Is this just a matter of the value not being super important in that spot? Or is there something going on with voltage that would match two 10Ms?

Resistors in series are additive. So 2 10M resistors connected in series is 20M of resistance. Most carbon film resistors are 5% tolerance. With 1 22M resistor you are within tolerance range. With such high values anyways, you are not likely to perceive a 1M difference out of the tolerance range anyways.

-Dan

[PicknStrum]

...One thing I didn't get a ton of clarification on (and I'm hoping to get here) is with V1 LNFB section. The layouts here show two pairs of 10M resistors in series on each side of the .047 cap. Jelle told me he was unable to get 10M's but some of the Dumble's he's looked at use single 22M's on each side of the resistor instead of the pair of 10M's so he advised me to do the same. I absolutely trust is expertise - I'm just curious why this substitution works. Is this just a matter of the value not being super important in that spot? Or is there something going on with voltage that would match two 10Ms?

Resistors in series are additive. So 2 10M resistors connected in series is 20M of resistance. Most carbon film resistors are 5% tolerance. With 1 22M resistor you are within tolerance range. With such high values anyways, you are not likely to perceive a 1M difference out of the tolerance range anyways.

-Dan

Ahh - massive brain fart on my part . I always get confused between series vs. parallel resistors and capacitors. I kept thinking if you have two 10M's in series, the resistance remains 10M but that is wrong. Resistors in series are additive and capacitors in parallel are additive. Thank you!

[PicknStrum]

Received the chassis from Solandfa and I'm really happy with it. A few minor issues that don't bother me at all - most can be fixed with a drill. I posted all of the issues / things I noticed in the recent ODS Chassis thread so I won't rehash all of them here. The biggest items will be to cut out an IEC hole and I'll have to sand my grounding points. The only other, slightly bothersome thing is that the DIN jack holes overlap with the main DIN hole - again, not a huge issue to me. I read on another thread that I can remove HAD's name with "techni-tool flux." Any other tricks for removing the name while keeping everything else intact? Here are a few photos. Starting to get some parts trickling in so hopefully I'll have some more updates soon.









Also, I did get my cradle built based on the stickied thread about amp cradles. This would've been awesome for my 2 previous builds but better late than never.

[sluckey]

Hey, I recognize that cradle!

[PicknStrum]

Hey, I recognize that cradle!

That's right! I was going to mention "sluckey's design" but didn't realize you were on TAG. I love it.... Fantastic design that even a poor woodworker like myself can put together. Thanks for posting it!

[norburybrook]

the cutout for the 'din 'socket was originally for a switchcraft 5 pin XLR which may drop straight in just like the original with some holes to drill . They're expensive though most people use midi type din sockets these days which are a lot smaller. The XLR is a lot better physical connection and a lot easier to work with too so if you want it like HAD did it I'd recommend it. I got mine from mouser when I did my #102 in a 'Dumble' chassis clone like this as it was cut out perfectly for the switchcraft XLR.

edit: found a pic.

dumble 102 rear.JPG

M

[PicknStrum]

Another small update as parts are still coming in. Decided to get the pedal wired up. As you can see, I'm taking the green vibe to the max - going green pedal, knobs, toggle caps, LED. Also, I decided to just do the OD, PAB, and FET Boost for now. If I decide to make the mid-switch footswitchable, I can add that later but taking your guys' advice for now.







Also finished staking eyelets - I was surprised how much I liked that whole process. I'll be making my own boards from now on. The G10 board is awesome - thanks for strongly urging that Martin! Note: the boards aren't oriented correctly - still waiting for hardware and to populate them (obviously).

Another thing you may notice is I was quite easily able to get the "Dumble" name off the chassis along with other errors and / or writing that I didn't think was necessary. I used denatured alcohol and cotton pads. I doused the pads in in the alcohol and then taped them to the the writing I wanted removed (while covering the writing I didn't want removed). Let the alcohol sit for 10 to 20 minutes and then it scraped right off with my fingernail. I did try acetone at first to no avail - denatured alcohol proved worthy!





Norbury: I love the Cream / white tolex in your build - I may get the itch to copy you there. I typically leave my cabinets finished in wood stain, shellac, or poly but I may dip my toes into tolex this time. I blame you

[norburybrook]

Lovely work there

Cream tolex is nice. From my own perspective Tolex covers a multitude of sins.....

I use glue and screw with 'bondo' epoxy body filler underneath that tolex knowing it doesn't matter as it will be covered. It's strong and functional.


Good luck with your build it's going to be great, I can see that already.


M

p.s. when I made my own boards I used 1/16 eyelets for the actual relay tab holes. I only ever did this once as I realised I could buy PCB relay boards for a few cents.... it was fun though.

[PicknStrum]

Lovely work there

Cream tolex is nice. From my own perspective Tolex covers a multitude of sins.....

I use glue and screw with 'bondo' epoxy body filler underneath that tolex knowing it doesn't matter as it will be covered. It's strong and functional.


Good luck with your build it's going to be great, I can see that already.


M

p.s. when I made my own boards I used 1/16 eyelets for the actual relay tab holes. I only ever did this once as I realised I could buy PCB relay boards for a few cents.... it was fun though.

Thank you!

Wow - yeah I had a hard enough time getting the 1/8 holes to line up. I can't imagine how the 1/16 holes would've looked if I did them. I could not find pre-made relay boards for the life of me. Where did you find them for a few cents? Or are you talking about the little board that you can plug the relay into and then fit that to the eyelet; like the little socket-thingys?