ODS in Progress

[ChrisM]

Hi Guys

Working on a 50W #124 ODS. I am going to update this thread as I build, try and get feedback on how I am doing.

So far I have gotten the chassis and almost all the parts needed for the build. Still waiting on pots, wire, OT, PT and a few other random things.

I did a bunch of chassis work and got most of the parts mounted.

[IMG:640:480]http://img.photobucket.com/albums/v610/ ... ingTop.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... eneral.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... ingEnd.jpg[/img]
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... ngBack.jpg[/img]

Now on to a question. I got this really nice sturdy 5pin DIN jack.
[IMG:640:480]http://img.photobucket.com/albums/v610/ ... kSmall.jpg[/img]
It's way too small though. How do you guys mount these? I am using the same part as specified in the layout.

Another question. Isn't there a double ground on the bias pot. It is grounded through the pot's metal casing and also through a wire running back to a ground point?


Chris...

[tubedogsmith]

It looks like you have your power supply board mounted backwards. That chassis is punched in the back for one of the big XLR round jacks. They're pretty expensive, like $24ea. or so.

[Pete]

Isn't there a double ground on the bias pot. It is grounded through the pot's metal casing and also through a wire running back to a ground point?

Not sure what you are referring to. Check your schematic, the bias pot does not directly connect to ground, one leg connects to a resistor to ground. pics look nice.

[talbany]

Not sure what you are referring to. Check your schematic, the bias pot does not directly connect to ground, one leg connects to a resistor to ground. pics look nice.

Kinda hard to see the other ground wire from this shot however look on the right side of the pot you can see where he has it soldered..(the layout below shows where he has it grounded) he does this in case the pot comes loose with no ground there tubes will run away on you ... ..Follow the layout grounding scheme here and the amp will be nice and quiet...Build looks good so far..

You can get those big ass 5 pin jacks @ Mouser.....Tubedogs right they are expensive....The cost of being authentic.,,If you need the part # let me know I'll look it up on my other laptop...

Good Luck!!!


Tony VVT

[UltraHookedOnPhonix]

Here's the Mouser part number for the 5-pin XLR jack that Dumble used:

502-C5F ($26.77)

[martin manning]

Hey Tony,

This was brought up in another thread, but the wiring around the B+5 filter seems to be wrong in the layout, The attached shows how I think it should go; see if you agree. There is also the labeling on the Level and Ratio pots (switched, should go Ratio, Level L to R as viewed from the inside; wiring is correct). You should put a date and version number on it too ;^)

MPM

[ChrisM]

Thanks tubedogsmith for noticing the PSU board, that's a quick easy fix.

Does anyone have one of those footswitch jacks on them? I am in Canada and just received a $123 order from Mouser. I had to pay $66 of custom fees at the door so I am not running back to order from them. Maybe an alternate source?


I think I was the one who brought up those issues MPM in the files section. Should I follow the schem for wiring the dropping line?


EDIT: That pot casing makes direct contact with the chassis so it is ground. The 27K bias resistor connects to the pot casing. There is a wire running from the pot casing back to ground point #3.

[tubedogsmith]

Just make sure that you wire the amp so you can change dropping resistors in the power supply fairly easy so you can adjust them according to your PT voltage.

[talbany]

Hey Tony,

This was brought up in another thread, but the wiring around the B+5 filter seems to be wrong in the layout, The attached shows how I think it should go; see if you agree. There is also the labeling on the Level and Ratio pots (switched, should go Ratio, Level L to R as viewed from the inside; wiring is correct). You should put a date and version number on it too ;^)

MPM

Martin

I knew it... the layout I posted was an older version... Just wanted to illustrate the grounding scheme like I mentioned...The finished version (with all the corrections you mentioned) is on my other laptop that now has a WICKED!! virus I am contending with so I couldn't post it...I should have mentioned that....Sorry


Tony VVT

[dogears]

Chris,

Why would you build an exact replica of #124 as a 50 watter? The difference in cost and effort is minimal and you can always use a half power switch. The 100 watter is what #124 is and that is what you should build IMHO. The chassis is also designed for 4 output tubes.

The 100 watters do have a different feel and girth than the 50 watters....

[ChrisM]

Chris,

Why would you build an exact replica of #124 as a 50 watter? The difference in cost and effort is minimal and you can always use a half power switch. The 100 watter is what #124 is and that is what you should build IMHO. The chassis is also designed for 4 output tubes.

The 100 watters do have a different feel and girth than the 50 watters....

Maybe at some point I will make it into a 100W. I have already ordered a 50W OT though. 100W would be way over kill for my situation anyways. Wont be too hard if I ever decided later that I wanted 100W.

In the end when I am done I will have a 50W D amp. I doubt it will be to #124 specs. I am sure some things will have to change and tweaking will take a while. I just want a cool, great sounding D amp

[dogears]

Cool... As long as you understand tweaks are always part of the equation!

The 100 watters are really no louder in practice fwiw. Just fuller.

Chris,

Why would you build an exact replica of #124 as a 50 watter? The difference in cost and effort is minimal and you can always use a half power switch. The 100 watter is what #124 is and that is what you should build IMHO. The chassis is also designed for 4 output tubes.

The 100 watters do have a different feel and girth than the 50 watters....

Maybe at some point I will make it into a 100W. I have already ordered a 50W OT though. 100W would be way over kill for my situation anyways. Wont be too hard if I ever decided later that I wanted 100W.

In the end when I am done I will have a 50W D amp. I doubt it will be to #124 specs. I am sure some things will have to change and tweaking will take a while. I just want a cool, great sounding D amp

[ChrisM]

Ya, the tweaking part should be interesting. Looking forward to hearing it stock first though.

Btw I am getting metal covers for the extra octal and noval socket holes.

Cool... As long as you understand tweaks are always part of the equation!

The 100 watters are really no louder in practice fwiw. Just fuller.

Chris,

Why would you build an exact replica of #124 as a 50 watter? The difference in cost and effort is minimal and you can always use a half power switch. The 100 watter is what #124 is and that is what you should build IMHO. The chassis is also designed for 4 output tubes.

The 100 watters do have a different feel and girth than the 50 watters....

Maybe at some point I will make it into a 100W. I have already ordered a 50W OT though. 100W would be way over kill for my situation anyways. Wont be too hard if I ever decided later that I wanted 100W.

In the end when I am done I will have a 50W D amp. I doubt it will be to #124 specs. I am sure some things will have to change and tweaking will take a while. I just want a cool, great sounding D amp

[talbany]

100W would be way over kill for my situation anyways. Wont be too hard if I ever decided later that I wanted 100W.

This is something that has always mystified me when people state that I will never need a 100w amp..They always equate the wattage immediately with respect to the amps volume.... When in actuality it has more effect on TONE than volume.. The difference in volume between a 50w and 100 is about 3db..barely audible...I believe playing through those early 100w Twins, Plexis, Hiwatts has fooled us into thinking a 100w guitar amp is overkill..In my opinion this rule doesn't apply to these amps since most of the breakup character is produced by a gradual increase in gain and a tight powerful output section..I know there are quite a few builders here who love there 50's and that's great... good for you..My ears tell me if your going for that classic tone that made these amps what they have become Benchmarks..the 100 watter is a very large part of that..
I play my 100 at home in small clubs and never had to switch down to 50 it takes a while to get used to but you get the hang of it you'll never look back!!


Tony VVT

[greiswig]

This is something that has always mystified me when people state that I will never need a 100w amp..They always equate the wattage immediately with respect to the amps volume.... When in actuality it has more effect on TONE than volume..

One question I've had: how much of the tonal difference has to do with power, and how much has to do with 2 versus 4 tubes? For example, if you put a pair of KT88s or 6550s in a 2-holer, you could get closer to a 100W amp than to a 50W. 'Course the tubes sound different from 6L6's, too...