chipdog

Nicely laid out list. It looks correct as far as I can tell. To be smart, I think it wise to order a few more (2-3 maybe?) of each of the parts, particularly the large 470 ohm 5 watt resistor. They fit into a tight spot on the base of the power tubes and I boogered one up trying to get the bends correct. Better to have a few left over than come up short and have to re-order and pay an extra shipping fee.

Besides, more mods may come up and you might have a leg up on them with a few extra parts around. You just never know!

Cheers -
Ken

chipdog -

In a nutshell, a cap/resistor with a higher voltage rating is actually good. In the case of a cap being .47uf vs. .50uf, well, that's pretty close and getting the exact values aren't always possible. When you take the tolerances into consideration, +/- 5% in most cases, it's essentially the same callout.

Note that tighter tolerances are often preferred but you often pay a price premium for it. In most cases a really high tolerance, such as +/- 1%, isn't req'd. There are a couple of instances where that tight a tolerance is called for and I would stick with those for where they have been indicated to be used on the layout.

Hope that helps a bit.
Ken

hey poipounder57

Yes, there are some parts in Jack's list that aren't needed. I believe the 150K resistor is one of those, perhaps the only one as I recall.  Where I could, I just replaced like with like. It's nothing to be too concerned over. If we get to the point where we start trying to hear the difference between a metal film resistor and a carbon based one, we're over the top IMHO.  That's when this guy starts heading for the door!


Ken

Hey hywelg -

Just perused this post and, man, do you do nice work!  Very nice shots of your head and speaker cab. You're quite the craftsman, buddy.

Do you build cabs or do some form of woodwork for a living or is it just part of your hobbies? Forgive me if you said something on this and I just missed it.

Once again, great work, bro!

Ken
 

Hey poipounder57 -

You'll be damn happy when you get the project done. The wife was out this afternoon so I kicked the dogs out into the backyard and let 'er rip. You really, really, really can't appreciate what this amp is all about if you can't let it all hang and get the 6L6's lightly clipping at higher volumes. It's big-smiley stuff, my friend.

I also gigged the amp yesterday with a cab containing a single 12" G12-65. We played on a patio to an amused crowd that said that they could talk while we played. We try to keep volume levels quite reasonable (we do blues). Several listeners made some great comments on my playing and I attribute part of that to the OTS. While the OTS sounds unbelievable at higher volumes, it does very well at much lower levels too.

I think you get the point... the mods make a noticeable difference.

k

 

Hey poipounder57 -

Yes, I changed only the items I found marked in red on Jack's revised layout. I too had some extra parts, some redundancy or perhaps duplication, maybe? As some of the parts I ordered were the same but with different tolerances, I chose the ones with the tighter values. Jack posted where one of his earlier BOMs had extra items in it for a friend's amp. I used that list so I have a few items I won't be needing anytime soon.

If it turns out there are more changes that didn't get highlighted, hey, we're ahead on parts if we can use some of the same. I'm not concerned. The sonic results are worth the few extra parts. If more mods come along I figure they may come in handy then and if not, oh well... no biggie.

Cheers -
k

 

hywelg,

Have you tried talking to Mouser to see if they'll ship to the UK? I just checked their site and it looks like they do International orders. You'll probably get hit with premium shipping charges but you'll get everything you need. Just be sure your BOM is complete so you only have to do it once.

Cheers -
Ken

I finished the entire mod switch-out today. On faith and faith alone I put the chassis back in the cab, hooked everything up and turned 'er on.... I DIDN'T BREAK IT!! IT WORKS!!!

Boy does it work.... These changes make an amazing difference. The Clean channel is noticeably improved, the overdrive is smoother, more buttery.... the jazz setting was a joke before, now it's my preferred setting.

The Bright switch is more Fendery, the boost switch adds usable juiciness... I'm telling y'all this is the way to go. YES!!

Those of you guys that know all this, forgive me, please. My humble efforts with a 25-watt Radio Shack soldering iron - I bought several new tools to make this project go well - have paid off big dividends.

I'm one happy camper. Thanks to Jack Z. and all of you guys here that helped supply the tidbits of knowledge to make this a very satisfying effort.

Cheers -
Ken

BTW, Mondoslug, I just listened to your last clip there on Pg 17. That sounded really sweet. Nice playing, bro!

Ken

Thanks for the kudos, guys. Considering I was into several glasses of wine, I'm surprised I could even find my fretboard. We cut four tunes of which I thought these two at least had some merit. Glad they ran OK.

I was using either a '58 Les Paul or a Korean PRS on these, I believe the Lester was the more likely one. Speaker cab is an Avatar 2-12 with an older Greenback and a new G12-65 in it. The recording was done with a SM57 pointed right smack dab in the middle of the two speakers.

The question about the mid-range boost, it was off; the overdrive was on. Tone controls were something like T:4 M:3 B:3-4 OD:3-4 or something like that. The OD setting is pretty variable depending on where that internal OD trimmer is set. I was also working the guitar's volume and tone controls as well.

My buddy Ken furnished all the keyboard work and had a drum machine along as well. Basically he brought over all the recording gear. All I did was play guitar and furnish dinner (actually my wife did... haha!)

It was a fun way to spend a Saturday night, ya' know? 

Ken

It never hurts to have a few extra pieces around. The little devils might come in handy one day. 

Cheers -
k

Here are a couple of me and a good buddy, Ken Robarge, who dragged his recording gear and keys over to my place so we could have some fun... and, oh yes, record some music while we were at it.

Now guys, the playing here is not stellar. I was three-sheets to the wind, having drank ample amounts of wine and I was feeling pretty loose. Nevertheless, there's a bit of merit here on the OTS so take it for what its' worth. Bear in mind only the "snip" mods have been done to this unit. The brunt of the mods are yet to be done.

http://webpages.charter.net/ksheldon562/02%20Blues%20a%20la%20Mode.mp3

http://webpages.charter.net/ksheldon562/04%20String%20Theory.mp3

Please let me know if these puppies don't work for. Hopefully they will without issues.

Cheers -
Ken

 

I'll go add that to the list. When I was ordering, I noticed that the 120pF cap was something odd and should have questioned it. That's what I get for being in a hurry... oh well. Hind-sight is always 20-20. At least these caps are really inexpensive. Thanks for the heads-up, Jack.

OK, folks. Here's a complete, updated list of all the components (BOM if you will) that Jack prepared recently. This should be all you need to do the mods recommended so far. If somebody notices something wrong or missing, corrections would be most welcome!

140-XAL350V47-RC
350V 47uF 20%      2 ea.    2.650    5.30

588-45F470E
5watts 470 OHMS 1%     4 ea.    1.230    4.92

71-CW2B-3.3K
3watts 3.3Kohms 5%     3 ea.   0.760    2.28

75-516D475M063-E3
4.7uF 63volts 20%       10 ea.   0.270    2.70

598-CD16FD331JO3F
330pF 500V 5%      8 ea.   1.630    13.04

598-CD15FD391JO3F
390pF 500V 5%     3 ea.   1.310    2.62

140-500S5-121K-RC
Ceramic Disc Cap 500V 120pF SL 10%   5 ea.   .10    .50

660-MF1/2LLT52R222J
2.2K ohms 5%      10 ea.   0.070    0.70

71-RL20S-G-3.3K
½ WATT  3.3K OHMS 2%      10 ea.    0.230    2.30

660-CF1/2CT52R154J
150K ohm 5%     10 ea.   0.100    1.00

71-CMF60150K00FHEK
½ watt 150K ohms 1%     10 ea.    0.180    1.80

71-RL20S-G-220K
½ WATT 220K OHMS 2%    10 ea.    0.230    2.30

581-5KQ331JOCAM
500 volt  330pF 5%     5 ea.   0.250    1.25

581-5MQ391KOBAM
500volt  390pF 10%   5 ea.   0.240    1.20


660-CF1/2C184J
180K ohms 5%   10 ea.    0.050    0.50

660-CF1/2C154J
150K ohms 5%    10 ea.   0.050    0.50


Cheers -
Ken

It turns out that even living in a big town like L.A. (I obviously live there  ) doesn't get you electronics components easily anymore. What was I thinking?? I go down to a local old-school kind of electronics store and he doesn't have even a 1/4 of what I need. I had Jack's Mouser part numbers on my list. The store owner asked what those were, I told him, and he said "hey, I find myself ordering from Mouser too."

Bottom line... I now have a new order of all the goodies in with Mouser. Guess I'll get into the amp next weekend.

Who'd think getting all the right parts together would be a challenge all to itself?

Cheers -
k

Jack -

I'm re-posting a big thanks here. This is exactly what I and others here needed.

It seems to me that my concern for the caps holding any dangerous reserve current that could harm you is not warranted, that they seem to drain fairly quickly once the OTS shuts off. Has that been your observation or do you take other precautions when working inside your chassis?

I can't wait to get inside the chassis tomorrow!

Ken