Tweed Overdrive Special & Carolina Overdrive Special

[tubenit]

Hopefully you can decipher this illustration. The Mstr vol affects only clean channel

With respect, Tubenit

[Geezer]

If I'm reading the schematic correctly, it looks like when that switch is in the OD position, the wiper is disconnected and that pot becomes simply a 1M resistor to ground,  Therefore it would have no effect on signal level.  Is that correct

Yes, it affects only the clean section (as Tubenit said)

if that pot only effects the clean "channel", then I will locate it next to the clean tone control and label it something different.

That's what I did....labeled it "Clean Volume"

[tubenit]

DaGeezer,

How important was it to you to have the 250k  pot for the parallel triode in achieving the tone you want?

 I currently just have an on/off switch there. However, I  have a mini-pot that I can fit on the front of the chassis that is 500k.  I could either use it at 500k or put a 470k resister on the outside lugs.

I am debating whether to change out the switch for the pot?  Sounds like you found a "sweet spot" using the 250k pot. Am I understanding that correctly?

I changed the first .02 coupling cap to a .01 & then used a cap substitution box & found a "sweet spot" with paralleling a .001 cap.  It sounded quite a bit better to my ears. This is the coupling cap going into the clean tone stack.  I have no idea why paralleling the .001 made a difference like that but it did to my ears.  And it sounded more expressive than the .02 which almost sounded compressed/muted in comparison.  I used the cap substitution box to parallel about 7 different caps with the .01.  A .002 did not sound to bad either paralleled but I settled on the .001 and put a Mallory in there.

With respect, Tubenit

[bluestone]

Is there supposed to be a "third" lug for the 50 KL  trim pot?

[bluestone]

Right, but isn't that a 50KL pot on the board with the wiper going to a 68k resistor to pin7 of V2? I thought that was the pot on the BOM that was posted Hummmm...

[EL34]

The schematic I am looking at shows a wire going from the wiper right to pin 7, so you don't need a lug

I see what you are asking about on the layout diagram, there is a 68k in line, but that's not what shows on the schematic, so I don't know

The creators will have to answer that.
Jeff, I sent you a board and the lugs for you to examine

[tubenit]

Yes, it's cathode biased power amp.  DaGeezer uses a 430/10w resistor & I use a 360/10w with my lower voltages than his on the 5881's. Both use 150uf cathode cap & I substituted Hoffman parts 100uf & 47uf/100v filter caps.

The wiper of the trim pot goes to a wire (shrink tubed) to a 68k (shrink tubed) right on to the grid .............

OR you can do like the D-style amps and use a terminal strip.  And have the trim pot wiper go to the terminal strip lug and the 68k attach to the terminal strip lug to the grid of the 12A_7.

The SCH library with the schematic, layout, bill of materials and turret board template show a 68k grid resistor.

http://www.el34world.com/Forum/index.php?topic=9636.0

With respect, Tubenit

[EL34]

Note:
Any document references in the post above have been deleted in order to have all the current info on one page.
Just a heads up in case you see a reference to a attached document and there is no document.

The Tweed Overdrive special documents page is here
http://www.el34world.com/Forum/index.php?topic=9636.0

[tubenit]

Just one last  question Ok Im looking at the BOM. and it says 430k 10watt resister and on the layout it shows that one as 430r 10watt

It's 430 ohm or 430R not 430k.     The Bill of Materials has been corrected and updated 8/2/10


Tubenit

EDIT:  With over 119 posts on this thread, I decided to edit out some. I approached this thread from the perspective of someone perhaps wanting to read all of it months or a year from now.  So, if one of your posts about " I want to build one of those also" or "sounds good" or "I agree" got deleted ............ sorry. I wanted to keep it to the core essence of the evolving conversation and design of this amp.

[EL34]

Good idea, Boil it all down to the essence 

[tubenit]

Billjade was asking about a reverb version of the Tweed Overdrive Special. So I drew one up. Check for errors and make sure the schematic and layout match.  Hoffman is not making a board for this so you will have to make you're own.

The SCH schematic and layout is here:

http://www.el34world.com/Forum/index.php?topic=9636.msg88942#msg88942


The predecessor to the Tweed Overdrive was the Carolina Overdrive which uses a different style layout but does have reverb and VVR.
The Carolina Overdrive uses a D_mble style tone stack instead of the tweed tonestack. You can find SCH info on the COS here:

http://www.el34world.com/Forum/index.php?topic=8387.0

With respect, Tubenit

[stingray_65]

well I ordered the hoffman board, gathered Iron and other parts and found a piece of aluminum to brake into a chassis.

I'm wondering.. what kind of speakers are you guys driving with this amp?

[Boots Deville]

It seems in all the consolidation of files for this amp, that all the .gif versions got removed.

I may be geekier than most, but just last month on was on a camping trip, sitting around the campfire, reading this forum on my iPhone.  What's a brother to do when JSchem doesn't offer an iPhone app!

[EL34]

.gif of what?

There's a .jpg layout on the docs page

What do you want a .gif of?
It can be added to the docs.

[Geezer]

what kind of speakers are you guys driving with this amp?

I'm running a 12" Eminence Legend (1258) in a 1x12 closed back, front ported cab....a very run-of-the-mill speaker, but fairly "neutral" to my ears, which I like....IOW, it doesn't flavor the tone of the amp with piercing highs or massive lows or mids, but lets the natural tone of the amp shine thru. I like the punch of a closed back cab.

I used to use Eminence "Private Jack"s, but found the highs to be a bit brittle sounding.
I think Tubenit uses Eminence "Red, White & Blues", but I may be mistaken.

Tubenit (me) has used a Red,White and Blues & also a Cannabis Rex
(Emminence). I like both of them with the amp real well.  With respect,T

[Boots Deville]

Doug, sorry I wasn't more specific - a gif version of the final/latest schematic would be appreciated. thanks!

[Geezer]

Here's a gif for'ya.......

EL34 edit: I added Geezers .gif schematic to the documents page here
http://www.el34world.com/Forum/index.php?topic=9636.msg87475#msg87475

[stingray_65]

Thanks Geezer,
I have 1 Eminence Wizard and about a half dozen Celestion Super 65's, Both speakers I find very neutral to my ears.

The folks over there at the AX site helped me a while back design a great cab for the Wizard, it's a bit big, but its convertible back makes it very versatile. I can run the back open or put a ported panel to fill the back or seal it completely.

the port seems to make the cab boomier and the sealed gives it a compressed voicing. myself I like it open.

do you think a 2x12 would be in order? I would use the Celestions there. or if I run the 1x12 I would copy the wizard cab again, both are projects I wanted to do anyway (and a 4x12 1960a cab filled with the 65's)

[tubenit]

Guys,

I added a flipped SCH layout into the SCH library that has all the current information.

Same layout but the view is flipped meaning it's more like the tradition Fender layouts with pots on top & sockets on bottom.

I got my board, turrets and parts from Hoffman & hopefully will start populating the board this wkend.

with respect, Tubenit


NOTE:  I posted another soundclip of the Tweed Overdrive trying to demo some of the sustain that it has right here:

http://www.el34world.com/Forum/index.php?topic=9789.msg89093#msg89093

[bluestone]

Geezer or Tubenit,
Have you tried a switch out or pot on the neg. feedback? Just wondering if there would be any worthwhile changes at lower volume....

[tubenit]

There are two newly recorded Tweed Overdrive clips here:

http://www.el34world.com/Forum/index.php?topic=9789.0

http://www.soundclick.com/player/single_player.cfm?songid=9490676&q=hi&newref=1

There was some debate on this thread about using a VVR or a PPIMV. I'm gonna state that I think the VVR is a nice match for this amp (to my ears)!  I recorded this tune with the amp volume NO louder than my computer speakers at medium.

http://www.soundclick.com/player/single_player.cfm?songid=9488477&q=hi&newref=1

Excuse my sloppy playing but check out how easily the amp sustains.

IF you get a pop up that asks if you want the window closed ......... just click "NO".

With respect, Tubenit

[Tone Junkie]

Man that sounds good Jeff the sustain is Killer. Which switch mods did you end up going with for those two switches Im getting the board finished and need to look in that direction next. Bill   

[tubenit]

Thanks for the nice comment. This is the first soundclip that really captures the tone of the amp that I am satisfied with. My recording system doesn't work very well but it's passable if I use a VVR dialed way down.  The sustain is pretty amazing on this amp live.


I have four switches and only two were on.

The OD switch was on of course.

And the paralleled triod switch was on engaging the triode.
That's it.

The other two switches add a bright cap to the clean volume & then parallels a resistor on  cathode cap. The later is only marginally useful.

Building it again, I'd only have  DPDT (clean/OD) ........ a triode switch or do DaGeezer's 250k pot ........ & a bright cap on the clean volume.

With respect, Tubenit

[Tone Junkie]

Cool I will definatly go with the clean/ OD a must obviously. I already know from past builds I dont need the switch on the parallelled tube Ive loved everyone Ive had, the 250k pot is a must have, and a push pull on the 1meg clean volume for the bright cap sounds perfect. Thanks Guys . Bill

[sdp1234]

Does anyone have a drawing or schematic detailing how you are implementing the VVR for the Power Amp and PI.  I have some drawings here and they all have additional capacitors.  I just want to make sure I save room if I add this feature. 

Also wondering how different this amp would be with a resistor in place of the choke?  I'm going on vacation which gives me time to draw my layouts.  I'm hoping to be ready to start this and another build when I get back.

Thanks

[Geezer]

Does anyone have a drawing or schematic detailing how you are implementing the VVR for the Power Amp and PI.

Try this thread>>>>

http://www.el34world.com/Forum/index.php?topic=8387.0

wondering how different this amp would be with a resistor in place of the choke?

I think a resistor would work fine......I only used a choke on mine because I has one on the shelf, otherwise I would have gone with the resistor.

G

Mine has a resistor instead of a choke. Tubenit

[tubenit]

Does anyone have a drawing or schematic detailing how you are implementing the VVR for the Power Amp and PI.

and if you check the ARCHIVES ........ there are schematics, layouts, & photos and comments on doing this:

http://www.el34world.com/Forum/index.php?topic=6899.0

With respect, Tubenit

[sdp1234]

Thanks Geezer and Tubenit, I should have checked the archives first! Sorry for being Lazy.

[stingray_65]

Just a quick question here,
On all the various layouts that's been posted here for the TOS, I keep finding "S1" between the tone and drive pots.
I keep re-reading the posts and I'm clueless to its purpose.
Heck I even went so far as to find my readers and put my glasses on.

[tubenit]

That S1 switch was originally from my personal Tweed Overdrive (schematic and layout)  & I use it to switch the paralleled triode on or off.  (Geezer has a 250k pot in that function)   You could also use a spst for a bright cap on the vol pot  or to parallel a cathode cap or resistor.

So, essentially ........... it can be for whatever switching purpose that you would want.  Use a spdt or dpdt there ............ whatever

With respect, Tubenit

[TIMBO]

Hi guys, This amp has got me buzzing. I'm waiting on parts to arrive so a couple of questions. Can someone tell me when calculating current draw for the transformer size, what am i looking for on the tube data sheet or what is the current draw for this amp?I just want make sure i have the right size tranny for this build.I have a 50w plexi i built awhile ago and was going to do a few tweaks and a bit of fine tuning after this project. I have a Hoffman "hot switch" added which was posing a couple of small problems.This ment opening it up and doing some surgory.The question is,if the 5F6A bassman and the plexi are of similar build, if the hot switch was removed and the overdrive inserted(i had thoughts of not having a tone on the overdrive so that the only colour comes from the plexi)could adding the overdrive to the plexi make it sound similar to the Tweed Overdrive Special.Thanks

[tubenit]

could adding the overdrive to the plexi make it sound similar to the Tweed Overdrive Special.Thanks 

My guess is NO!  But I could be dead wrong.  We tried adding this overdrive to the HoSo56 preamp topology and it just did not work out for some reason. IF you try it .......... let us know and record some sound bits, please.


I think any trannie that is 140ma to 200ma sound work OK if the heater current rating is also high enough.

With respect, Tubenit

[tubenit]

Guys, I used a hammer (not a drill press cause I don't own one) & Hoffman's staking tool to install the turrets/lugs on the Tweed Overdrive Special Layout board.  Tutorial on how I did that with pictures is right here:

http://www.el34world.com/Forum/index.php?topic=9800.0

Only took me about 55 min to install 66 turrets including putting tools up.  

With respect, Tubenit

[Tone Junkie]

Tubenit two questions my friend. On the one tube reverb does it have an on off switch like other reverbs. Ive checked the archives found good info you put there just not that , and the Dwell for the reverb looks like a pot do you guys put that on the back or should i move it out to the front. Thanks Bill

Bill, the reverb doesn't have an on/off switch & I always put the dwell on the back.    With respect, Tubenit

[Geezer]

Well, played the amp for 3 long sets last night @ an outdoor gig.
Ran reverb & delay thru the effects loop.
Had a distortion box (Bad Monkey) hooked up ...........DIDN'T USE IT ALL NIGHT!

I got every tone I needed from the Clean/OD sections & by varying the Volume & Tone controls on the guitar.
I set the amp up on the "hot" side (fairly gainey when the guitar volume was dimed) then just rolled back the volume pot for a beautiful clean tone.....more "bluesy"?...just bring the volume up a bit.

I played Motown, Skinnard, beach music, Neal Diamond (  ), Rare Earth, Vince Gill, Righteous Brothers, Doobie Brothers........all with the exact same amp setup (clean/OD ONLY).

Got lots of (good) comments from the band members (& guys in the crowd) on the tone....best yet!

G

[tubenit]

Just to echo what Geezer said ..............

I played my Tweed Overdrive with the band & got some very nice compliments on the amp's tone from the band and audience. 

It cut thru the mix with no problem even with a loud keyboard player.  Whether on clean or overdrive & no matter whether playing rhythm or lead .......... it cuts thru very clearly even with the OD pushed. I had the paralleled triode on all the time. Harmonics are very nice even with chording/rhythm.

This is the first time I've played an amp with a relay switching OD. I like that feature. Very quiet switching from clean to OD.

I have found switching out 12A_7 types,  such as using either 12AX7 or 5751 or 12AY7 or 12AT7 in different positions, that every combination has sounded good to me and you can sure tailor your tone to a wide variety doing that.

Only thing I am not too keen on is the PPIMV which doesn't sound good dialed below "6" to my ears. Above that sounds fine to me.

With respect, Tubenit

[bnwitt]

Only took me about 55 min to install 66 turrets including putting tools up.  

With respect, Tubenit

Man, I never realized how much time my drill press saves me.  I just did an AB763 110 turret board on it in 5 minutes.

[tubenit]

I just did an AB763 110 turret board on it in 5 minutes.

WOW! That's quick!  You did 22 turrets a minute which is one turret every three seconds. Blazing fast.

With respect, Tubenit

[bnwitt]

Well the drill press is set up for nothing but turreting and I load all of the turrets at once.  Then, I can jump from one turret to the next about every 2-3 seconds.  Every once in a while one hangs up and causes others to pop out with the release jolt.   But preventing that is all in the angle of the board when each turret is pressed.  I don't know how many thousands of turrets I've pressed with this setup but it's a lot.  I used to do a lot of time and motion studies when I was in the Hotel business and I have a tendency to analyze every process to death for time savings.

I had to use a hammer on the turrets for the bias trimmer since they're so close together and I can see how that would take a long time one by one.

[Geezer]

Another soundclip posted HERE>>>> http://www.el34world.com/Forum/index.php?topic=9817.new#new

[tubenit]

When Geezer changed the internal 25k trim to an external panel mounted 50k trim .......... I thought "nah, that probably wouldn't be useful to me" ................ & then he changed the on/off switch to the parallel triode to a 250k fattness pot stating that there was a "sweet spot" in there somewhere just back off full on.  And I thought "yeah, right (sarcasm) it can't be that much different or better".

You ever hate it when someone else is SO right compared to your preconceived notions!!  

OK, Geezer you're right ......... there is a "sweet spot" with the fatness pot.

And you're also right in that the 50k external pot that you can adjust is a "must have" now that I've tried it.

Turns out that I can get an even smoother sounding overdrive by turning the 50k trim pot to about "7" and lowering the drive pot to about "2" & having the OD level at about "7.5". I mean it gets super smooth OD that way withOUT losing any useable harmonics and sustain.  The 50k trim pot also allows an incredible amount of distortion/OD to be used IF someone wanted that  (trim at "7", drive at 7.5 & OD level at 2).

OK, I admit it ........... you told me so & you were right!!  UGH!  

In fact, the pot that I change the least is the clean volume pot. It has the least adjustment when I try dialing in a particular tone.

Sorta kinda with respect, Tubenit

[Geezer]

Another soundclip posted HERE>>>> http://www.el34world.com/Forum/index.php?topic=9817.new#new

Updated the soundclip....I had the tracks off time from each other, that's why it sounded so BAD!  

Give another listen........please

[bnwitt]

Attached is my stab at a faceplate and control names.  Ignore the rear plate as it is not for this amp.

[tubenit]

Barry,

Superb job!  I like it.   Nicely done.

Any chance of fitting on a manual spdt switch to go with the relay?

With respect, Tubenit

[jojokeo]

Now that's an overdrive special on steroids. I've never seen so many gain, drive, and level adjustments and so few tone controls in one amp. Nicely done you guys.

[Geezer]

I've never seen so many gain, drive, and level adjustments and so few tone controls in one amp.

GOAL! 

Yeah, all we have to worry about is the amount & type of distortion/overdrive, NOT fiddlin' with the tonestack all the time! 

I absolutely LOVE this amp!

G

[Fresh_Start]

Geezer - love the soundclip

Bnwitt - great job on the plate design

You all have created a thing of beauty in my humble opinion.  Thanks!

Chip

[Tone Junkie]

I really like the names you have on the face plate there perfect , I would only add two things on the back the effects in and out and the footswitch plug in for the channel switch. Bill

[jojokeo]

Yeah, all we have to worry about is the amount & type of distortion/overdrive, NOT fiddlin' with the tonestack all the time! 

What a novel concept, it's about time something like this comes along. This one's going to be hard to top? BTW, good playing G :)

Turns out that I can get an even smoother sounding overdrive by turning the 50k trim pot to about "7" and lowering the drive pot to about "2" & having the OD level at about "7.5". I mean it gets super smooth OD that way withOUT losing any useable harmonics and sustain.  The 50k trim pot also allows an incredible amount of distortion/OD to be used IF someone wanted that  (trim at "7", drive at 7.5 & OD level at 2).

I have found that combined with higher amounts of gain/overdrive and the more raw signal and/or mids dialed in, the smoother the inherent drive also (in my DumbleWatt). To describe it is to think of the lead in Bob Segar's "Down on Main Street", or many of Santana's solos.

[bnwitt]

Barry,

Superb job!  I like it.   Nicely done.

Any chance of fitting on a manual spdt switch to go with the relay?

With respect, Tubenit

It's getting a little tight on the 17.5" chassis but I'll do some squeezin'.  Any other suggestions?