D'Mars Overdrive Special

[JBP]

Anyone have experiance using a 6v DC wallwart for relay power supply?

[Willabe]

May be I don't explained well what I mean

Quote from Doug

(1) I have added 4 lugs around the relay socket lugs so that I have better points to solder external wires to. Wires that lead to tube sockets, pots, etc are soldered to these extra lugs. It's much easier and better this way, it can be very difficult to solder to the lugs under the relay socket. Note that these extra lugs are jumpered under the board with short pieces of buss wire.

from this page

http://www.el34world.com/projects/relay_switch2.htm

Hope now you can understand what I was meaning. K

Ohh. I think I get it now. Maybe.


                 Brad     

 

[proaudioguy]

OK,  I think this is correct for 3 relays.    I will revise this to have the 3 relays be operated by a 5pin DIN.  Just don't have time now.


Can someone please confirm that it is correct?  Thanks.


With respect,  Tubenit

In addition to removing the resister wouldn't you have a cap before and after the regulator?  I haven't built a rectified regulated power supply in 20 years.  I used to build audio projects with + and - 15V regulated supplies.  Start with a 24 Volt AC transformer.  I don't remember any of the math.  Right now trying to figure out if 5 volt AC can be turned into 5V regulated DC.  I suspect it can.

[Willabe]

In addition to removing the resister wouldn't you have a cap before and after the regulator? 

Yes, look in reply #196, #197.


                  Brad     

[sluckey]

Right now trying to figure out if 5 volt AC can be turned into 5V regulated DC.  I suspect it can.

It can for very light, fairly constant loads. But 5VAC only gives 7 volt pulses to smooth out with the filter cap and then pass on to the regulator. Not enough headroom for good regulation. The regulator gets starved too easily.

[Willabe]

I think you can use a voltage doubler on the 5v wind and get 14vdc.

                     Brad      

[tubenit]

OK,  I revised the layout board to foot switch wiring.  

Is this CORRECT???

Don't forget that the 6.3 volt source is different on some trannies
You have no center tap using two 100 ohms
center tap to ground
champ style with one leg going to chassis

Be careful here. If your filament winding has a CT connected to chassis, DO NOT CONNECT THE NEGATIVE SIDE OF THIS RELAY POWER SUPPLY TO CHASSIS! Doing so will poop the bridge or PT, maybe even both. Better to be safe and float this relay PS. There is no reason to connect the negative side to chassis. That means to also isolate any chassis connectors used to connect to a FS.

I am not quite sure about the different 6.3v arrangements. It's late, I'll read that tomorrow and post any questions for clarification.

I hope this is helpful to someone.  I've had a difficult time making sense of the relay stuff.  

I am currently using one relay with an isolated ft switch jack.  I have two 100 ohm resistors for the 6.3v ground.  

Question:  Would I still need an isolated jack using the 5 pin DIN?

With respect, Tubenit

Doug's 5 pages of  relay explanations are here:  http://www.el34world.com/projects/relay_switch.htm

[DummyLoad]

Right now trying to figure out if 5 volt AC can be turned into 5V regulated DC.  I suspect it can.

It can for very light, fairly constant loads. But 5VAC only gives 7 volt pulses to smooth out with the filter cap and then pass on to the regulator. Not enough headroom for good regulation. The regulator gets starved too easily.

use 3VDC coil small signal relays. the light loading of the relay won't be much of burden if you use a good amount of capacitance and an adjustable VR such as the LM 317; better still the LDO LT-108x types. CPU 3.3V LDO regulators will work as well.

http://pewa.panasonic.com/assets/pcsd/catalog/ds-catalog.pdf   3VDC relay - mouser stocks them.

--DL

[sluckey]

Question:  Would I still need an isolated jack using the 5 pin DIN?

No. You would only need to isolate a jack if the body of the jack is actually one of the electrical connections, such as the Switchcraft 12 phone jack that has the 'sleeve' connected to chassis unless you use fiber bushing washers. None of the DIN connecting pins actually touch the chassis when mounted, right? So the DIN is already isolated.

[kagliostro]

Anyone have experiance using a 6v DC wallwart for relay power supply?

this is a kit, but documented in a very good way, here you can find a lot of info about that



http://www.homotix.it/catalogo/alimentatori-e-dc-dc-converter/breadboard-power-supply-5v-3-3v

http://www.sparkfun.com/tutorials/297

http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Kits/Breadboard%20Power%20Supply%20v10.pdf

http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Kits/Breadboard%20Power%20Supply%20v10.zip

the schematic apply DummyLoad idea using an LM317

K

[tubenit]

No. You would only need to isolate a jack if the body of the jack is actually one of the electrical connections, such as the Switchcraft 12 phone jack that has the 'sleeve' connected to chassis unless you use fiber bushing washers. None of the DIN connecting pins actually touch the chassis when mounted, right? So the DIN is already isolated.

Thanks for the answer, it is appreciated as always, my friend!

With respect, Tubenit

[Geezer]

Question:  Would I still need an isolated jack using the 5 pin DIN?

No........None of the DIN connecting pins actually touch the chassis when mounted, right? So the DIN is already isolated.

That's correct

[Willabe]

OK,  I revised the layout board to foot switch wiring.  

Is this CORRECT???

No, I think where the LED is hooked up is backwards. Anode of the LED goes to + of relay and  LED current limit 180R goes to ground.

And I think it would be easer to follow the din plugs pin layout if you would use pin 1 for switch 1, etc.....


               Brad    

[tubenit]

Willabe,

There won't be an LED in the amp.  It will only be in the footswitch box.

With respect, Tubenit

[tubenit]

OK,  here is the D'Mars (dual) OD Special Hoffman style layout board.  You can see that his D'Mars board will work perfectly w/this.

Compare schematic with layout & check for errors.

The SCH version is here: http://www.el34world.com/Forum/index.php?topic=14302.0

A big thanks to Geezer for sharing his design with dual OD switching!

With respect, Tubenit

[Willabe]

Willabe,

There won't be an LED in the amp.  It will only be in the footswitch box.

Ok, but doesn't the LED's anode still have to be powered from the + side of the relay?

And in this verson of Dougs relay drawing you have the diode across the relay listed as the LED and no LED current limiting R.
                

                            Brad      

[Willabe]

I had in mind to use a 9volt battery inside the foot switch box if possible.

Well now that's a horse of another color than.     


                  Brad     

[proaudioguy]

Right now trying to figure out if 5 volt AC can be turned into 5V regulated DC.  I suspect it can.

It can for very light, fairly constant loads. But 5VAC only gives 7 volt pulses to smooth out with the filter cap and then pass on to the regulator. Not enough headroom for good regulation. The regulator gets starved too easily.

I could use a 7803 perhaps and use 3 volt relays.

[proaudioguy]

Right now trying to figure out if 5 volt AC can be turned into 5V regulated DC.  I suspect it can.

It can for very light, fairly constant loads. But 5VAC only gives 7 volt pulses to smooth out with the filter cap and then pass on to the regulator. Not enough headroom for good regulation. The regulator gets starved too easily.

use 3VDC coil small signal relays. the light loading of the relay won't be much of burden if you use a good amount of capacitance and an adjustable VR such as the LM 317; better still the LDO LT-108x types. CPU 3.3V LDO regulators will work as well.

http://pewa.panasonic.com/assets/pcsd/catalog/ds-catalog.pdf   3VDC relay - mouser stocks them.

--DL

Thanks

[kagliostro]

CPU 3.3V LDO regulators will work as well.

Something like the LD1117 ?

http://it.rs-online.com/web/p/regolatori-di-tensione-low-dropout/6869782/

K

[sluckey]

Right now trying to figure out if 5 volt AC can be turned into 5V regulated DC.  I suspect it can.

If you just want to energize some 5 volt relay coils, you don't need regulated voltage. Just put two or 3 diodes in series with the positive unregulated voltage and each diode will drop approx .7 volt. So, if you have unregulated 7 volts unloaded, two diodes would drop this to about 5.6v (unloaded). Probably just about right for a bank of 5V relays.

[tubenit]

For any of you wanting a D'Mars OD Special Hoffman board, I just want to confirm that all of Doug's part fit great!

I finally got the mosfet installed & it's a perfect fit!

With respect, Tubenit

[tubenit]

For those of you are willing to check the cap outer foil orientation to have a quieter D'Mars OD Special,  ............  I am offering this information to consider.

with respect, Tubenit

[kagliostro]

Hi Tubenit

Your activity on sharing your project always increases in details

You are becoming always more refined 

K

[EL34]

Looks good Jeff

[proaudioguy]

For those of you are willing to check the cap outer foil orientation to have a quieter D'Mars OD Special,  ............  I am offering this information to consider.

with respect, Tubenit

I did this when I built my twin but I didn't mark them.  Good idea.

How hard is it to add reverb without messing up the balance of everything of else?

[proaudioguy]

OK,  here is the D'Mars (dual) OD Special Hoffman style layout board.  You can see that his D'Mars board will work perfectly w/this.

Compare schematic with layout & check for errors.

The SCH version is here: http://www.el34world.com/Forum/index.php?topic=14302.0

A big thanks to Geezer for sharing his design with dual OD switching!

With respect, Tubenit

I was wondering if someone for educational purposes would draw the signal flow on the layout and schematic and perhaps mark up the gain and losses, frequencies affect and such.  This would help me a ton, and I bet it would help a lot of others too.  I really like the sound of this amp (still want to hear chords) and I love the layout, it's so clean.

[Geezer]

How hard is it to add reverb without messing up the balance of everything of else?

Check this out> http://www.el34world.com/Forum/index.php?topic=9812.0

You could add a small "daughter" board for the reverb components so you could still use the Hoffman board layout

[proaudioguy]

For those of you are willing to check the cap outer foil orientation to have a quieter D'Mars OD Special,  ............  I am offering this information to consider.

with respect, Tubenit

I am trying to learn....
Comparing the board to the layout.
Is the 220R from 3 to 7 under the board?
Is the lead from 7 to power under the board?
I know you have mentioned the pigging back arrangement of caps on lug 5 and lug 19 (5 and 21 of the layout).  Is there any issue with mixing electrolytic and those non-polarized (Xicon?) caps?  Why would anyone use electrolytic caps at all?

The spacing of the components (especially the cap) directly to the right of E2 on the layout board seems squirrelly.  Was Mr Hoffman using different components there?

The lug numbers do not match the layout.  The layout seems to have skipped the number 4 when numbering.  The layout numbers the center lug of the mosfet 8, while the board doesn't number the mosfet lug.  Would it make sense to number all of the lugs on the layout we could do this ourselves, but it would be easier when discussing it, and place matching numbers on the schematic?  Maybe these numbers can be in a different color than the tube pins, XLR pins, etc.

[tubenit]

You could add a small "daughter" board for the reverb components so you could still use the Hoffman board layout

Absolutely could be done very easily. The reverb is essentially an amp in itself. You could make a very small board and mount it on the back panel or parallel it above the Hoffman board.  Or you could use terminal strips.  Easy enough to do. Put the dwell pot on the back or use a dwell resistor.

Regarding the questions ...............  

I simply haven't soldered the 220R on yet. It's that simple.  No issue mixing the Xicon & electrolytic or I would not have done it.

The spacing to the right of E2 is great. If it concerns you, ....then you can easily make your own board or spacing if needed, since I drew up a SCH layout that you can modify. Hoffman is a genius, IMO. No, same components.

OK the lug numbers don't match the layout.  You're capable of relabeling them for yourself so they match.

My goal is to give you guys a foundation to build your own D'Mars OD Special.  

Unless there is some really major mistake (that someone needs to let me know about), I will let you figure out the details.  That is exactly what I had to do for myself, and frankly you have far more information to work with (given the info I provided) than I had starting from scratch.  It has taken me about a yr to figure this amp out to design it, & hrs and hrs to provide this information freely to the forum.

Honestly, if someone is going to do a build like this & tweak it, they have to accept responsibility to figure some of this stuff out on their own. I say that with good will & IMO, that's just the way it is. And typically, if I have posted a question, it's after I've researched stuff out like crazy and was still uncertain.


With respect, Tubenit

[proaudioguy]

You could add a small "daughter" board for the reverb components so you could still use the Hoffman board layout

Absolutely could be done very easily. The reverb is essentially an amp in itself. You could make a very small board and mount it on the back panel or parallel it above the Hoffman board.  Or you could use terminal strips.  Easy enough to do. Put the dwell pot on the back or use a dwell resistor.

Regarding the questions ...............  

I simply haven't soldered the 220R on yet. It's that simple.  No issue mixing the Xicon & electrolytic or I would not have done it.

The spacing to the right of E2 is great. If it concerns you, ....then you can easily make your own board or spacing if needed, since I drew up a SCH layout that you can modify. Hoffman is a genius, IMO. No, same components.

OK the lug numbers don't match the layout.  You're capable of relabeling them for yourself so they match.

My goal is to give you guys a foundation to build your own D'Mars OD Special.  

Unless there is some really major mistake (that someone needs to let me know about), I will let you figure out the details.  That is exactly what I had to do for myself, and frankly you have far more information to work with (given the info I provided) than I had starting from scratch.  It has taken me about a yr to figure this amp out to design it, & hrs and hrs to provide this information freely to the forum.

Honestly, if someone is going to do a build like this & tweak it, they have to accept responsibility to figure some of this stuff out on their own. I say that with good will & IMO, that's just the way it is. And typically, if I have posted a question, it's after I've researched stuff out like crazy and was still uncertain.


With respect, Tubenit

Hey man I'm just trying to learn how all this goes together.  I haven't even grasped the signal flow as yet.  Not planning to build it, more interested in how it works.  That's why I stated trying to learn....  There was absolutely NO criticism. 
I'm working on my own amp (and layout) and I am trying to figure out WHY certain components are layed out certain ways, pointing certain directions.  This requires asking questions.  Since you have a great sounding amp, it makes sense to question WHY it sounds so good. Can you dig it? 

[proaudioguy]

I simply haven't soldered the 220R on yet. It's that simple.

Simple answer to a simple question
 

No issue mixing the Xicon & electrolytic or I would not have done it.

Why use electrolytic caps at all?  Since they end up having to be replaced when they wear out/ leak?  I thought it was related to the polarization.

The spacing to the right of E2 is great. If it concerns you, ....then you can easily make your own board or spacing if needed, since I drew up a SCH layout that you can modify. Hoffman is a genius, IMO. No, same components.

I asked this because it looks like the lugs are under the cap rather than on each end of it.  Thought perhaps a different size cap was used.

OK the lug numbers don't match the layout.  You're capable of relabeling them for yourself so they match.

I was thinking the amp layout and schematic with the labeling and notation could be a sticky or an article in how tube amps work and what parts do what.  Obviously I can label it myself but that doesn't help a thousand other noobs (or me) learn how AC and DC audio circuits work.

No disputing the design is awesome and Dougs layout is genius, and the dual OD controls are way cool too.  You spent a lot of time learning about how this stuff works so you could design your own.  I'm trying to do the same thing.  Having a full time job and no chance of ever retiring, and a family that demands much of my time off, I have to learn quick.

[John]

Having a full time job and no chance of ever retiring,

Welcome to the club! 

Talking about noobs and understanding things, in my own experience the simple circuits are the ones to learn on. My first build was Geezer's SoHo with the 2 relays, and quite honestly it was above me at that time, even though it's a pretty simple circuit for most guys on here. I had the dickens of a time getting the relays to work (Hoffman's law) and then when I did it hummed like hell because I didn't understand proper layout and grounding as well as I should have. I finally removed them and just used the one set of pots. 

Tubenits latest amp looks like one I'd like to build someday, but not any day soon. I have more to learn before I attempt all those fricken switches and stuff.  And imvho, builds like that require more time than I've got at the present. I'd spend more time trying to remember where I'm at in the build than actually building it.

[John]

Anyone have experiance using a 6v DC wallwart for relay power supply?

And this is something I've wondered about myself. Has anyone done that?

[EL34]

Anyone have experiance using a 6v DC wallwart for relay power supply?

And this is something I've wondered about myself. Has anyone done that?

Why do that when you have a free power source in your amp from the heaters?

You can even send DC down a cord from the amp to a switch box to control LED's

[Geezer]

Posted a sound clip > http://www.el34world.com/Forum/index.php?topic=14266.msg135711#msg135711

LOVE this amp!

G

[tubenit]

Guys, check out Geezer's amp and playing ...............   

http://soundcloud.com/dageezer/dumars-noodles1-0

My friend,  that tone is as good as it gets, IMO!!   I think your amp (& surely your playing too ........ sounds better than mine). Incredibly articulate, clear, touch sensitive tone.  

Geezer's got more info on the link in the previous post.

THANKS so much for sharing it!   with respect,  Tubenit

[Geezer]

Thanks T.....

in listening to the recording, it's hard to believe this is an approximately 10w amp! (the DuMars preamp into a 2x6AQ5A pair PP, cathode biased) It sounds & feels MUCH BIGGER!
The volume of the amp is quite low (you can easily hear me stepping on the footswitches & switching the guitar pickup selector @ about the same volume as the amp!)

Thanks for listening!

G

[woolly]

Hey Jeff , you're a good player, nice stuff. That 150 sure sounds good. Nice job!

 oh, the amp don't sound bad either. 

[John]

Wow. Nice tone, even nicer playing!

[Tone Junkie]

Sounded real good, you covered a lot of area to let us get a good idea of how she sounds.
Thanks Bill

[EL34]

Yeah, it's sounds great

[Attila]

Hi Gents,

fantastic build and I aim to get mine started ASAP - @Geezer brilliant playing and tone 

 Q: is the BOM as posted by EL34 regarded as final ? 

Attila

[tubenit]

is the BOM as posted by EL34 regarded as final

The BOM that I posted (yesterday) in the SCH file noted EL34's revisions. 

Please note that the BOM does not reflect the dual pots on the OD that Geezer uses nor does it reflect the relay switching. So if you use the dual pots and relay switching, then you'll need to add that to your parts list.

Having said that,  I strongly encourage you to check the BOM against the schematic for accuracy. Won't take long to do and may save yourself some frustration in not having a part that you need.

With respect, Tubenit

[Attila]

Noted and thanks

[EL34]

I added several parts to stock this week that are used on this project

I have a post here with the list of new parts I stock
http://www.el34world.com/Forum/index.php?topic=14415.new#new

[tubenit]

E34,

THANKS for stocking the parts!  This is a FUN amp to play and is very touch sensitive with a real sweet tone, IMO.

NOTE:  I found using the Hoffman D'Mars board that I needed shielded wires going to the treble pot from the .002 and .02 caps on either side of the wiper.  Something about crossing the B+ created some hum.   I tended to use shielded wires on any long runs to the relays also.

Hoffman's board works great and is VERY sturdy in appearance. 

With respect, Tubenit

[moonbird]

Tubenit -

When you get a chance - could you please measure and post the voltages at PS taps C, D, & E of the  D'Mars (dual) OD Special design. No hurry.

The soundfiles you kind gents have posted to date sound very much to my ear like those for a *Gkar Rumblier* if you catch my drift. Between this design and the HoSo - these are two of my dream amps that I never thought I could ever afford. My heartfelt thanks to both you and Geezer for all you have done for all of us!!   

[tubenit]

Voltage chart was already  in the SCH file.  Doesn't matter if it's a dual or single OD controls as far as the B+ rail goes.

With respect, Tubenit

[jojokeo]

The soundfiles you kind gents have posted to date sound very much to my ear like those for a *Gkar Rumblier* if you catch my drift.

What the heck, are you afraid the lawsuit man is going to come after you or get you for saying a certain name that something just may happen to sound like!? Please...stop the nonsense. We're all grown ups here.