Custom Champ to Herzog modification

[SILVERGUN]

As a spinoff of TubeGeek"s thread on possibly starting a new Garnet build, I want to start a discussion about the Garnet Herzog,,,and my attempt to modify my Custom Champ to Herzog-like operation.... maybe even just make it a switchable option to run the Champ stock, or run it as a Herzog...
It basically looks like a Champ with a built-in attenuator/ line out

My biggest question is:
-Is a Champ OT gonna handle this OK?....(mine has a 4 and 8 ohm secondary tap, and a 7K primary)...and if so, Is there a "most efficient" way to run it?....or shall I say, "least harmful" way to run it?

I imagine that 6 ohm resistor across the OT secondary is gonna get pretty hot? ...(I'll use min. 25watt- wirewound)

Any other suggestions?

[kagliostro]

Hi SILVERGUN

I think the 6R resistor is to be connected to the 4ohm intake on the OT

and it will reflect to the power tube an impedance that is higher than the 4ohm speaker

I think it was a wanted thing but I don't know if the 145a189 OT was a 5k or 7k impedance unit

I think the way you can do it in the safest way is to connect a 4R resistor to the 4ohm tap or an 8R resistor to the 8ohm tap, this will result in a reflected impedance very similar to the impedance given by the speaker

---

Have you considered also this schematic ?



K

[SILVERGUN]

Have you considered also this schematic ?

Thanks K!
I'll take ideas from either one, and just picked the first one because I know I like the Randy Bachman sound..

Here's a quickly modded schematic for anyone's review, to ensure I'm on the right track:

[jjasilli]

I'm all in favor or re-creating a Herzog. 


A simple alternative is a pedal.  Or,  to use a small bottle pentode in a the preamp, maybe switchable, to get the right output curves.  It could even drive a small tranny like a Champ OT or reverb tranny to couple to the rest of the amp (a buffer stage, tube or SS might be needed). 

[SILVERGUN]

I'm all in favor or re-creating a Herzog. 
A simple alternative is a pedal.  Or,  to use a small bottle pentode in a the preamp, maybe switchable, to get the right output curves.  It could even drive a small tranny like a Champ OT or reverb tranny to couple to the rest of the amp (a buffer stage, tube or SS might be needed).

Thanks jj,
For now, for me, I have to stick to just trying to mod this Champ to get the experience, and see where it goes....
Both breadboards are populated, and I have an amp due in May,,,,,so I'm looking for a quick transformation of a pre-existing unit.......this Champ is really just my shop tube tester 

I just want to hear what it does......sounds like it might be pretty cool, and get me closer to that sustainer effect I like 

[HotBluePlates]

My biggest question is:
-Is a Champ OT gonna handle this OK?

Sure, there's nothing really different going on inside the amp. You're just absorbing the output power in a load resistor and tapping off some signal to drive another amp.

(mine has a 4 and 8 ohm secondary tap, and a 7K primary)...and if so, Is there a "most efficient" way to run it?....or shall I say, "least harmful" way to run it?

If you use a 6Ω resistor, then either way is "just as far off." Pick either and play.

You don't care about efficiency and maximum power output, because you're wasting the power into a load resistor and tapping only a small fraction. So perfect matching doesn't matter. And you're not gonna hurt the amp because it's not running any harder than it ever was. It's still just a 6V6 amp, just a resistor instead of a speaker.

I imagine that 6 ohm resistor across the OT secondary is gonna get pretty hot? ...(I'll use min. 25watt- wirewound)

The amp is 4w output max, right? And we normally say double the wattage for safety? So 10w seems fine.

Be aware that the "25w aluminum wirewound resistors" are only 25w when bolted down to a substantial heatsink. In free air, the 25w version only carries a 12.5w rating. The higher-power ones are down to 40% of advertised power rating in free air.

I mention that because it looks cool but might be more expense than benefit. However, it does have a convenient mounting method.

Have you considered also this schematic ?

Thanks K!
I'll take ideas from either one, and just picked the first one because I know I like the Randy Bachman sound.

Notice that K's schematic has a speaker output on the right side, and an attenuated output on the left side. You can keep or ignore the bright switch. But your schematic as drawn can only be operated as a "pedal" and without a speaker.

... modify my Custom Champ ...

Once you added that tone control, it became a "Custom Princeton"! 

[SILVERGUN]

What might be the purpose of this cap?  and why the super high 1600V rating?

 Why the .003 value? (.003uf I assume?)

[SILVERGUN]

Thanks for all of that HBP...remember what it was like to make everything more difficult sounding than it actually is?....I give myself so much unnecessary brain trauma, but I'd rather ask and feel embarrassed than assume and start a fire 

I'll use that big wirewound because I have them laying around here....
I should be able to do this VERY quickly,,,, and as a temporary "mod" I'll be able to get a feel for the future use

It obviously won't be an exact copy, but I have a feeling it'll give me a good feel for 'what it is'

[HotBluePlates]

What might be the purpose of this cap?

You know what a cap does: it passes highs (in this case to a.c. ground).

If you've ever actually made a line out attached to the speaker jack and plugged that into something like a PA, you know why they added the cap to dump highs... there's a lot of high end hash that normally gets rolled off by the speaker response, which doesn't happen with your line out. In this case, you have all the top end of the distortion to roll off so your sound isn't too trashy.

You could try with and without the cap. I would switch with the amp off.

... why the super high 1600V rating? ...

B+ is 320v, so that's where the plate idles. On the positive peak of your note, the tube draws more current and the plate voltage swings down towards 0v. As that electrical signal (note) swings negative, the plate current decreases and the plate voltage rises. It should kick up to 2x the idle voltage, or to 640v.

A 600v cap isn't enough, and a 1000v cap may have too little safety margin (you don't want this cap to fail and short your power supply). 1600v was probably the next available voltage rating.

Why the .003 value? (.003uf I assume?)

Yes, 0.003uF. Probably rolls off enough treble without taking out too much. Get a bunch of 1600v caps, and see which one you prefer.

Notice the Herzog schematic doesn't indicate any filter caps, so you use what you got there.

[SILVERGUN]

I threw this together after I punched out today and ran the Champ into it, and then into a high gain project that already sounds good on it's own..I turned the Champ all the way up, and turned the preamp gain on the main amp down and WHAM-O!!
...it's just the attenuator side of the OT on the Herzog....

The guitar feels alive, but I can stand right there and everything punches, and sustains,,,and holy moly 

Instead of a treble booster, it's a full range choked down cranked Champ booster.......really, really cool!!

[printer2]

Anybody notice the 1k cathode resistor on the 6V6?

[SILVERGUN]

Anybody notice the 1k cathode resistor on the 6V6?

Well now that you mention it,,, I assume that the schematic that K posted is an "improved" version...

I don't think it's necessary to squeeze every last drop of output out of that 6V6 so I imagine the 1K is just there to calm it down a bit...

The cool part of this is that I don't think anything is a deal breaker...make a good sounding amp,,,load it down and tap a signal off of it.

Try it, you'll like it!.......most awesome overdrive "pedal" I've ever heard

[printer2]

In the past I read about running output tubes at higher impedances and some like the sound, just thought it might be part of the sound. I have been thinking about putting together a 'preamp' of sorts lately. Small signal tubes though.

[SILVERGUN]

In the past I read about running output tubes at higher impedances and some like the sound, just thought it might be part of the sound.

Well, you might be right...
On the first version schematic I posted, they are running a 6ohm resistor on (what I imagine is) a 4ohm OT

I used a 10ohm resistor on the 8ohm tap and it sounds good so I can't disprove the theory.

[HotBluePlates]

I threw this together after I punched out today ...it's just the attenuator side of the OT on the Herzog....

I'd think all you need to do is package that attenuator, rather than make a new build (or alter your existing one). Then it's a ready add-on accessory without a lot of work.


Nice to hear it sounded good to you!

Anybody notice the 1k cathode resistor on the 6V6?

I didn't look at that the first time.


Try it if you like... It should just bias the tube cooler; depending on how much cooler, it may change the distortion flavor. I could draw a loadline, but I'd want to hear it myself to be sure. It's a safe change to taste-test.

[printer2]

Anybody notice the 1k cathode resistor on the 6V6?

I didn't look at that the first time.


Try it if you like... It should just bias the tube cooler; depending on how much cooler, it may change the distortion flavor. I could draw a loadline, but I'd want to hear it myself to be sure. It's a safe change to taste-test.

Yrah, I was doing something after and it poped into my head I had a brain fart, the bias voltage would be higher not the impedance.

[Ed_Chambley]

I threw this together after I punched out today and ran the Champ into it, and then into a high gain project that already sounds good on it's own..I turned the Champ all the way up, and turned the preamp gain on the main amp down and WHAM-O!!
...it's just the attenuator side of the OT on the Herzog....

The guitar feels alive, but I can stand right there and everything punches, and sustains,,,and holy moly 

Instead of a treble booster, it's a full range choked down cranked Champ booster.......really, really cool!!

Dave, break this down to idiot level for me.  You know I am way to much of a backwards hillbilly to get this.  You have a line out coming from your champ going to this.  Is the resistor accepting the load from the output of the champ.  Did you modify the champ?  How?  I looked at the Custom Champ schematic and I do not understand what you have done.  You have a transformer of of some sort.  Break it down so a third grader can build it.


All you guru's can get it, but remember us new to this stuff.  If you are tapping off the champ circuit to a setup like a active direct box and using a volume control, I have not seen a photo of the mods you have done to the champ.  The photo of the metal angle, resistor and input jack is just your interface and gain pot, correct?  What transformer are you using?  Why the resistor?  What is that resistor and pot doing?  I do not see it in the Custom Champ schematic.  Is it there?


Sorry if I missed it somewhere in the thread, but I cannot get my mind wrapped around it as presented, however I am very familiar with Herzog and Bachman's Les Paul Rig.


I have the coolest 5C1 with a pentode triode switch I built with Mercury Iron and it is built in a large pedal box just ready, but I don't know how to do this cool thing you are doing.  The Champ is your preamp, right?  Then you can use this with the proper impedance to hit the front of another amp like Jimbob's Marshall Major.    You can crank the major and use the tone of a SE amp so basically you would have a SE amp that you have cranked the snot out of going to another preamp maintaining a very tube sound with rich second harmonics and not have to have diode clipping.  Do I get the idea, or am I just typing stupid stuff?

[HotBluePlates]

Break it down so a third grader can build it.

[Jeff Foxworthy Voice: "Are you smarter than a Canadian?"] 

Champ Speaker Output Jack -> Input jack of load resistor/pot combo -> Output jack of load resistor/pot combo -> Input jack of your Big Amp

See the Herzog snippet below. A Herzog is really just a tweed Champ, but instead of a jack from the OT secondary for a speaker, it has a load resistor to take the place of a speaker and a 1MΩ pot. The wiper of the pot is the output of the Herzog to plug into the input jack of your other amp.
The only pieces Dave had to assemble (because he already has a Champ) are those circled in red: Load resistor, pot, output jack and a not-drawn input jack from the Champ's speaker output to the load resistor. Just unplug your Champ's onboard speaker and plug it into the load resistor.

The actual Herzog also adds a 150kΩ resistor between the pot wiper and output jack hot lug, and sets the source impedance at 150kΩ minimum.

[SILVERGUN]

Nice to hear it sounded good to you!

Thanks man,,,it really does, and I might have never thought of it if you hadn't brought it up....
I really appreciate that fact and I thank TG for starting that thread......and, I still think it will be cool to build this into an amp!

Do I get the idea, or am I just typing stupid stuff?

Yup 

It went from idea to testing in one afternoon so that's why it was presented so haphazardly 
And now that HBP has cleared it up,,,here's more details:
As I was staring at the schematic and trying to throw together an amended version of what I would have to do to build it into my Champ, I realized that I didn't have to....
It's just an attenuator with an adjustable line out, so you can run one amp cranked into it, into another amp...

So yes, I could take a Tele, plug it into my Champ, crank it into the attenuator, into Jimbo's Major, and finally get that thing sounding good 

Any amp into any amp, with the right resistors....
I'm sure you've got 2 amps laying around 

Anyone looking for a VERY powerful OD tone should try this!....I'm sure the Reverend Billy G did!
I'd be really curious to hear Tubenit's thoughts on this....he has a way with describing sound, that I can't duplicate.

If I wasn't so busy on another project, I'd be all over this now,,,,but it's gonna have to wait a couple weeks.....
I'm really looking forward to seeing what TubeGeek does with this and hearing his reaction!

[SILVERGUN]

What are the potential dangers of overloading the input of the second amp?
How would I know?.....and what should I do to prevent it?

[sluckey]

What are the potential dangers of overloading the input of the second amp?

Gross distortion.   

How would I know?

By the smile on your face. 

.....and what should I do to prevent it?

Install a bypass switch.   

[SILVERGUN]

I knew I could count on YOU   

Anyone ever melted a 12AX7 grid?....not on purpose?

[HotBluePlates]

Math Time.


You know the rough power output of the "little amp" you intend to use with your attenuator. You know the speaker load/load resistor value.


Power = Voltage² x Resistance, so...
Voltage² = Power / Resistance, and...

Voltage = √(Power / Resistance)

Example:
You have a 4w Champ (full 4w and maybe a hair more if turned full-up). You have a 6Ω load resistor in your Herzog-alike. What is the full voltage across the 1MΩ pot?
Voltage = √(Power / Resistance) = √(4w / 6Ω) = 0.82v RMS (that's 0.82v * 1.414 = ~1.16v peak).

1.16v peak is pretty close to the bias voltage of the input tube, and the maximum input it could handle. The 1MΩ pot knocks that down as much as you need. Recommendation: Start with the 1MΩ all the way down, and turn up as needed.

If you used a bigger amplifier, you'd have a bigger voltage at the "speaker" (across the load resistor), you might have to turn the pot down more.

You'll probably get a nasty unusable sound before you could redplate the output tubes of the big amp, but I'd keep an eye on them if you crank that 1MΩ pot very high. You also better have speaker rated for double the maximum output power of your big amp... The RMS power of a squarewave is 2x the RMS power of a sinewave, and your distortion is turning the output into a square.

[sluckey]

Anyone ever melted a 12AX7 grid?

You have a 150K resistor between the level pot and the output jack, right? If so, you're not likely to melt the grid.

[Ritchie200]

So yes, I could take a Tele, plug it into my Champ, crank it into the attenuator, into Jimbo's Major, and finally get that thing sounding good 

Really?!?!  Really?!?!


Slucky, thank you for keeping this overachieving maniac grounded.


Jim

[SILVERGUN]

Anyone ever melted a 12AX7 grid?

You have a 150K resistor between the level pot and the output jack, right? If so, you're not likely to melt the grid.

I didn't realize that would be enough protection....in case this gets into the hands of a true madman 

Really?!?!  Really?!?!

Really!! ,,,you've gotta try this.
Even YOU will appreciate this! 

And then you should stop back and remind me how awesome I am for bringing it to your attention.
LC
The Overachieving Maniac

[SILVERGUN]

Recommendation: Start with the 1MΩ all the way down, and turn up as needed.[/size][/font]

If you used a bigger amplifier, you'd have a bigger voltage at the "speaker" (across the load resistor), you might have to turn the pot down more.[/font]

You'll probably get a nasty unusable sound before you could redplate the output tubes of the big amp, but I'd keep an eye on them if you crank that 1MΩ pot very high. You also better have speaker rated for double the maximum output power of your big amp... The RMS power of a squarewave is 2x the RMS power of a sinewave, and your distortion is turning the output into a square. [/font]

Great, simple explanation HBP!

And that's something I forgot to mention...
I didn't have to crank the Champ past 6 to get "the best" sound....AND the output control sounded best down around 3 because anything higher just started to mush the front end of the main amp..

Now, I'm sure that will change from amp to amp,,,,but at least I won't feel unsafe as I demo this for my friend who brought in his little Champion 600 today so we can run Champ into Champ.....he got a little nervous about me possibly damaging the input of his amp, and I was unclear of the explanation.

Not anymore, thanks to you 2!
 

I'll make sure we keep the volume of the 2nd champ down so as not to blow his speaker....thanks again for that

[jjasilli]

I think Ritchie200's post is also my question.  The Guess Who proved long ago that the Herzog sounds great as a front end into the main amp.  But that was then, when options were more limited.  And, options that did exist were less widely known and maybe not readily available everywhere.  This might have been more true for our Canadian brethren at that time.  Hence, Canadian guitarists were blowing-up their amps, trying to cascade them!  Gar Gillies to the rescue.


KOC says that any desired tone can be created in the preamp, leaving the power amp for a clean boost only.  By extension, tone can be created in a pedal in front of an internal preamp, including a tube pedal.  The Herzog is sort of a shoebox size version of that.


But, as Ritchie200 points out, any amp into a dummy load/attenuator, and a DI box with a line out > main amp, should be able to duplicate the Herzog approach. 


This leaves me wondering if the Herzog, though functional, is obsolete.  Nevertheless, if it feels good, do it!

[SILVERGUN]

But, as Ritchie200 points out, any amp into a dummy load/attenuator, and a DI box with a line out > main amp, should be able to duplicate the Herzog approach.

I think that was me jj....don't give that guy too much credit....it's already tough for him to get his head in and out of the door to his house (even after they put in a slider)....he said 2 meaningful words,,,really and really
 

This leaves me wondering if the Herzog, though functional, is obsolete.  Nevertheless, if it feels good, do it!

I might have had an exceptional experience based on exceptional circumstances.....
The "Champ" I'm using is a higher gain model, and the breadboarded amp is a very high gain "metal" amp

And,,,I've been known to get a little exciteable.......sometimes over stuff that has all been done before

I've been trying for the last year and a half to get a super powerful feeling OD tone that didn't mush out, and retained note separation, etc., etc.,
There was definitely something to this that made the guitar feel very alive and playable,,,but also punchy and dynamic
But, due to my lack of overall experience,,,I'm not aware if you can get this same feeling with just a tube preamp pedal 

Going back to your earlier post, I'm starting to think that it might be cool to scale it down into the front end of an amp.......as a future project..?

And,,, obsolesence hasn't stopped anyone from building or wanting another 5E3 

[Stankfut]

I'd think all you need to do is package that attenuator, rather than make a new build (or alter your existing one). Then it's a ready add-on accessory without a lot of work.

Great idea! I'm thinking maybe put this in a pedal box? With a foot switch bypass?


Of course, here are my questions...... With the exception of the load resistor, is this any different than a line out? I know that this is meant for the input of an amp, but if you run this into the return of an effects loop, what would happen? I'm thinking a loud Champ? What effect does using a resistor over a speaker have on tone? Negligible?

I've never actually heard of the Herzog before.....the things I learn here....Thanks!

edit: D'oh! I'm not sure what exactly I would bypass....

[Stankfut]

And,,, obsolesence hasn't stopped anyone from building or wanting another 5E3 

Yes please!

[jojokeo]

I knew I could count on YOU   

Anyone ever melted a 12AX7 grid?....not on purpose?

Not a 12AX7 but I have melted a JJ EL84 grid or two   
 
BTW, nice thread. Would a variable line out from the speaker tap not be enough or close to the same effect desired? Or a line out from an attenuator? (haven't had much time to assimilate & contemplate this idea yet)

[SILVERGUN]

....here are my questions......
1) With the exception of the load resistor, is this any different than a line out?
2) I know that this is meant for the input of an amp, but if you run this into the return of an effects loop, what would happen?
3) What effect does using a resistor over a speaker have on tone? Negligible?

1) I guess we'd have to know which line out design you mean?....but generally not that different than one that's tapped off of the secondary of the OT
2) Same effect, just entering into the signal chain of the 2nd amp later....
3) Usually has the perceived effect of a loss of highs...kinda like throwing a big heavy blanket over your speaker cab....so much so that I don't like using my 50 watt attenuator, because it just changes the tone too much...I have labeled it the "tone-sucker 50"

[SILVERGUN]

Would a variable line out from the speaker tap not be enough or close to the same effect desired? Or a line out from an attenuator? (haven't had much time to assimilate & contemplate this idea yet)

Yeah, it's a variable line out off of an attenuator...
I almost asked "where's this thing been my whole life?"
And now I realize.....THD hotplate 

I'm sure guys have been doing this since Randy Bachman,,,,but it's news to me 

And, I'm not giving the Herzog enough credit...I'm sure that there is something special about that design that is worth copying....if nothing else, just for historical accuracy...
I have a feeling TubeGeek's gonna take care of that

[Ed_Chambley]

Now it's a thread to be proud of.  Got some attention.

[SILVERGUN]

Now it's a thread to be proud of.  Got some attention.

I was just about to post....
"I'm getting some telepathic signals from the Ed Chambley outpost"...." I have a feeling he's got 2 amps and a big resistor and something really cool is about to happen"

[Stankfut]

3) Usually has the perceived effect of a loss of highs...kinda like throwing a big heavy blanket over your speaker cab....so much so that I don't like using my 50 watt attenuator, because it just changes the tone too much...I have labeled it the "tone-sucker 50"

I have a Weber MASS, supposed to be better than a regular attenuator because it uses a speaker driver, right? Its okay at low levels of attenuation, but I feel the same way as you at higher levels. Definitely doesn't make my 5E3 a beadroom amp when the baby's sleeping


 Back to the Herzog....since its going into the front end of another amp, I'm guessing some of the treble loss can be dialed back in?


I guess I just need to do it already.....have to see whats in the parts bin......

[SILVERGUN]

Back to the Herzog....since its going into the front end of another amp, I'm guessing some of the treble loss can be dialed back in?

Yup,,,it made my tone controls more responsive on the second amp because there's more signal pushing through there now

Here's a simplified schematic, just in case anyone is having trouble seeing what I did:

[jojokeo]

Now it's a thread to be proud of.  Got some attention.

Yep it's been upgraded to a string now...string theory even?   
 

Yeah, it's a variable line out off of an attenuator...
I almost asked "where's this thing been my whole life?"
And now I realize.....THD hotplate 

And, I'm not giving the Herzog enough credit...

I keep thinking of Whitey Herzog the old baseball manager and his hotplate was either in his locker room or at homeplate arguing with an umpire. 
 
*you can use a cap or two along with a line out to preserve highs. Infact you just might have too much so you have to dial it in maybe with a series resistor too. You should be able to dial in what you want this way. Even put a few on switches and it would look even cooler too. Just another approach to try?
 
 

[terminalgs]

Anyone ever melted a 12AX7 grid?

What would melt the grid?  the output's  voltage or current?

As for the 150ohm resistor in series, that doesn't hit the 12ax7 grid immediately,   you've got a 47K or 68K grid stopper in there right?

Besides (maybe before) The Guess Who, Ray Davies used to plug the output of a small cheapo fifties 10W "little green amp" into the input of his AC30s.   I think he probably did so without much  ANY engineering.. more of a "goesinta" and "comesouta" approach.

When you turn the volume down on the champ, eventually you get a clean small signal and your "champ-stomp-box" becomes a unity gain device.   Lets say that is at "3" on your volume pot.  If you use a relay, or a vactrol, or neon/ldr to switch your champ's volume from "3" to "10", you've got a real foot switchable MAX-overdrive effect.   a lot of what you read about people building the Herzog is complaints of not knowing how to switch it in and out, (I guess they didn't have a Bradshaw),  but it could be in-line all the time, possibly, as long as you can use a footswitch to attenuate it down to clean unity. 

[clyde]

The Hoffman board has discovered Herzogs.  I have one here, haven't used it for years, found it impossible to balance the saturation with the volume.  It's a rather flawed design that needs some tweaking shall we say.  My clearest memory of the damn thing is burning my finger on the 6V6 tube, man does that thing run hot!  Best of luck guys.

[terminalgs]

You'll probably get a nasty unusable sound before you could redplate the output tubes of the big amp, but I'd keep an eye on them if you crank that 1MΩ pot very high.

I dunno, it might the best sound you've ever heard!  right before it blows up!


http://youtu.be/m52-IFMXI60


skip to 26:00 "I pretty much blow up tubes, output transformers"  and then note when he says he turns the volume "half way up". ????  If you watch the entire thing, you'll see he puts boost pedals in series with Big Muffs and like, so I suspect the voltage hitting the inputs of the '68 JMP,  the '68 Super Bass, and the '73 DR103 is 5V or 10V???   who knows,, but it blows transformers and tubes with amps set to "4" or "5".   and the 80W tweed twin,,   although it is mic'ed, it seems like he uses the twin as a monitor more than anything.

[Ed_Chambley]

Now it's a thread to be proud of.  Got some attention.

I was just about to post....
"I'm getting some telepathic signals from the Ed Chambley outpost"...." I have a feeling he's got 2 amps and a big resistor and something really cool is about to happen"

Telepathic, hell I can't even spell it much less know what it means.  Are you saying my Tele is pathetic?  I seriously do not think you really mean this.


Clyde is correct, but where there is a will.  ANyway, someone looking for high gain really does not want much clean.  All joking aside, I have a monster 50 watt (called that because of dissipation, but that is a different thread of a different color) that will produce the loudest goodest tone I have ever heard.  That is what happens when you push the snot out of EL34's.  It is wired to a 2, 12 cab with 2 webers, a silver bell and blue dog both 50 watts, so it pushes the just enough without blowing them.


Pretty easy to control the setup with a A/B footswitch.  Seems like a fun thing to do.  Have not played American Woman in years.  Think I will play the Krokus version.  Now who doesn't like that.


I can say this, the champ I have sounds great and the 5C1 can be boosted quite a bit on the front.  I feel sorry for my EL34's tho.  I promise you this, I will replace the mullards in it with some Servicemaster Internationals.  What an easy fun thing to do.


Before I knew any better, I used to daisy chain Super Reverbs from the extension speaker jack to the front of the next.  Sounded great and luckily, never tore one up.

[HotBluePlates]

Would a variable line out from the speaker tap not be enough or close to the same effect desired? Or a line out from an attenuator?

Yeah, it's a variable line out off of an attenuator...

Which goes to the heart of why I suggested just packaging the attenuator, ratherr than building a whole new amp device.


That said, there is some potential "magic" in the cap from 6V6 plate to ground cutting highs.

...since its going into the front end of another amp, I'm guessing some of the treble loss can be dialed back in?

You could.


But you've played though a fuzz box before, right? With those, generally the treble gets so nasty you want to cut treble. And that treble cut is what turns the fuzz-rage to the almost kazoo-like tone on American Woman.


Yeah, I suppose you can turn treble down on the big amp or your guitar, but it might be netter to not have it there in the first place. But what do I always say about experimentation? "I never argue with results." Try it and see what you think.

Anyone ever melted a 12AX7 grid?

What would melt the grid?  the output's  voltage or current?

What did Jojo say? That he hadn't killed a 12AX7 but has killed an EL84?
It will be voltage, applied to the output tube's grid. Mainly the positive excursion which drives the voltage of the grid momentarily positive (meaning, to a higher voltage than the cathode).


Normally, the grid acts like an infinite impedance and draws no current. When the grid is more-positive than the cathode, electrons flowing from cathode to plate can be attracted to the grid and flow out (when the grid is negative of the cathode, this does not happen). If enough grid current flows, that current times the grid voltage is power dissipated by the grid, which it usually is not rated to do. Make that power big enough and the grid can melt.


I think you would see redplating of the tube before that happens, but be advised it's something to consider.

As for the 150ohm resistor in series, that doesn't hit the 12ax7 grid immediately,   you've got a 47K or 68K grid stopper in there right?

That's 150kΩ resistor...

Pretend the 1MΩ pot is turned all the way down. Imagine you're at the input jack of your big amp looking back towards the output jack of the Herzog (or attenuator). Instead of seeing ground, you would see 150kΩ to ground.
This keeps the Herzog from completely shorting the input of the big amp. Maybe you and your bandmates are playing through the same amp (it's the old days)... If that 150kΩ wasn't there and you turned down your Herzog, you short out their input signal and nothing makes it through the amp.


So it's not absolutely necessary but it's performing a different job that a grid stopper. Something more akin to a channel-mix resistor.

[SILVERGUN]

We hung out tonight for a couple of minutes and put his Champion 600 into the Herzatt (new name--not in stone) into my Custom Champ with good results...
not earth-shattering, but better than either amp's stock form...

With the C600 on 10 (out of possible 12), and the Herzatt output on 3, into the CC on 3 we got a very cool, heavy overdrive that made everything seem fatter, stronger, bolder, AND noisier.....we both liked it a lot and he made me promise to wire him one up so he can run the C600 into his DRRI.

I added a 10R in parallel with the original 10R for 5R, since his C600 output is 4ohm,,,so that kept in line with the slightly high impedance mismatch.

As with any distortion, too much is too much, and there was a point where it just didn't make sense to go any farther,,,,and comparing to last nights results, I feel this would make a great addition to a medium gain amp that you want to push over the edge..

Its makes for a fatness machine that makes the guitar more playable and I have to confirm HBP's belief that treble is an issue, because I found myself rolling off the tone control on my amp.

I feel like this experiment can be expanded on as a concept, and utilized in a few different ways:
- Self contained Herzog type unit to put in front of any amp
- Self contained Herzatt attenuator to be used between any two amps (that meet the impedance and power requirements)
- Integrated Herzog as a "preamp" in a new build, to be voiced and optimized around that specific amp

Makes me think more about jjasilli's original post about the possibilities
Wish I had more time for this right now.

[TubeGeek]

Well this sure sparked some conversation!


Lot's of great info here, I am sure it will help me figure out what to do when I get to my project.


I am still thinking a self contained Herzog as a preamp and a dedicated amp on the other side too.  I'll make the herzog switchable so if I am not in the mood for crazy thick distortion, I can switch it off and have some note articulation back.


I'll report back when I am ready to begin.


Good job Silvergun!

[Ed_Chambley]

Just got finished running my experiment and I like it and think and think it is worth further looking into.  I did not notice any additional heat from the 6v6.  Tried a 5881 as well.  Sounded basically the same.  The champ I have only has a volume know so so all tone control was from the main amp.   I tried a couple of other resistors close the the 150.  Did not ever got hot.


I liked it, but full throttle is not possible since a champ muddies and simply is passing this along.  I tried it with a 9 watt se amp I have and was able yo get more distortion with less mud.  Either way, it is way more tuby sounding than any diodes which is sort of stupid to say.  I an not a fan of the new Marshall stuff, but must admit they have taken high gain into a new area.


Give me a little time to digest.  I may have some valuable input.  Not sure right now as I did not really do any tone shaping.   The el34's held up no sweat.

[PRR]

Bachman was running the Champ's (or similar) speaker output, no speaker, direct to his main amp. ...a "goesinta" and "comesouta" approach. Cool sound, BUT.....

He kept blowing-up the Champ OT. Severely over-driven amps get inductive kicks in the transformer which will punch-through any reasonable insulation.

Gar finally asked why this small amp kept coming back with blown OTs. A good businessman wudda just ordered a crate of OTs and pre-printed a stack of repair bills. No, he saw that a LOAD would greatly reduce the OT abuse without huge change of tone.

The full-bore output is really too much. He added a turn-down pot.

The Champ can deliver about 1 Amp into a load. A safe input for 12AX7 (any small tube) grid is 1mA or 2mA. He realized this, so add the series resistor so even full-up would not melt the 12AX7.

> a 150K resistor ...I didn't realize that would be enough protection.... ...a true madman

The Champ can only do what it can do. Output can't be more than the supply voltage divided by the OT ratio, maybe 8V peak. Taking 1mA as a safe limit for 12AX7 grid, we need more than 8V/1mA or 8K resistor. Many-many amps have 68K already. For those that don't, Gar threw something in. As high as 1Meg would reduce level, so over 8K and less than say 250K. Possibly he reached in his pants-cuff and found a 150K.

Assuming a 10 foot (now 3 meter) cable from Herzog to main amp, 150K gives a 3.7KHz high-cut, a perfectly reasonable way to take excess trash off the signal without harming the semi-harmonic overtones from the overdriven Champ.

The pot has to be well over 250 Ohms so that a common 1/4W pot can survive, and perhaps no more than 1Meg so the worst-case impedance doesn't lower the high-cut much. Again he may have had a 1Meg in his pocket or the edge of his bench. You can certainly use anything you got, 1K-1Meg.

[Ritchie200]

I think Ritchie200's post is also my question.  The Guess Who proved long ago that the Herzog sounds great as a front end into the main amp.  But that was then, when options were more limited.  And, options that did exist were less widely known and maybe not readily available everywhere.  This might have been more true for our Canadian brethren at that time.  Hence, Canadian guitarists were blowing-up their amps, trying to cascade them!  Gar Gillies to the rescue.


KOC says that any desired tone can be created in the preamp, leaving the power amp for a clean boost only.  By extension, tone can be created in a pedal in front of an internal preamp, including a tube pedal.  The Herzog is sort of a shoebox size version of that.


But, as Ritchie200 points out, any amp into a dummy load/attenuator, and a DI box with a line out > main amp, should be able to duplicate the Herzog approach. 


This leaves me wondering if the Herzog, though functional, is obsolete.  Nevertheless, if it feels good, do it!

YEAH, WHAT HE SAID!!!!!   See SG, when you grow up and build or buy a GOOD amp (see KT88) and start listening to some good music, you will achieve such status that you will only have to utter a single word twice - and everyone knows exactly what you mean.    I'm sorry, but you have a loooooong way to go....


ps jjsilli, I was actually just flabergasted that he would trod so flagrantly on the hollowed ground that is the heavenly tones emitted from my relic.  It had nothing to do with the Herzog!

[Ritchie200]

To jjsilli's point, I do think we are in new territory.  All due respect to KOC, but I have not seen any preamps with a blazing 6V6.  Many amps do not get on peak (as I call it) until the power tubes are working hard.  It is certainly true on all the old Marshalls and heck even the Fenders.  I have yet to hear a preamp that really sounds like a cranked amp.  This is certainly a new flavor!


Jim