Engl Fireball - keeping the basic stuff

[blackwood]

I must build this thing!:D

But.. I want to remove the FX send/return and footswitching sections from the schematic and simply build a basic head.

Preamp clean/lead + reverb send/return + power amp + 8 and 16 ohm outs and the power supply, that's what I want to keep.

Also, this amp is 60W and I'd like to make it 100W into a 2x12" cabinet.
So, more tubes to add, huh...

I've built a few solid-states so far and spent months reading and learning about tubes and stuff, talking to people who built them, but I can't make a new schematic alone. Which parts to leave out or which elements to change if something is cut out (like the footswitching section), how to add more power tubes to make it 100W etc.

I'd really appreciate all the help I can get on this one, as it's going to be my first tube amp:D The schematic is in the attachment, it would be too big to post it as a .jpg, so..

Thanks,
Igor

[blackwood]

for instance - can I simply cut of this whole FX loop section and connect CE6 to R33 or...??

http://i6.photobucket.com/albums/y248/glicerin/fireball.jpg

[Daver]

Not sure how the effects loop will pan out, but that schematic is seriously flawed. Where did you get it? I have no first hand knowledge of the Powerball, but a quick look at the schematic shows some mistakes. The Depth switch would do nothing as drawn. Either C3 is out of the circuit or shorted when the switch is activated. The 3rd stage has its grid tied directly to gound so it won't work. The Send stage has a huge 47nf cap across its plate. That would roll off a ton of highs. The Presence is wired like a variable negative feedback control. There are no caps involved with it and no AC cap to ground for V4B of the phase inverter. V4B also has its grid shorted to the top of R44. That amp won't work as drawn. Can anyone else proof my observations?
Daver

[Ray Ivers]

Daver,

FWIW, I concur with everything you posted. First tube build, complex circuit, confidence-low schematic; it sounds kind of like a non-starter to me.

blackwood,

The loop should come right out as you posted, but in light of the above, this would seem to be the least of the problems you'll have to overcome. As this appears to be an actual Engl schematic (I think), perhaps they really don't want people cloning their amps - even if it means making it more difficult for them to be serviced (although they may provide correct schematics to their authorized service agents).

Ray

[Joe N]

Daver,

FWIW, I concur with everything you posted. First tube build, complex circuit, confidence-low schematic; it sounds kind of like a non-starter to me.

blackwood,

The loop should come right out as you posted, but in light of the above, this would seem to be the least of the problems you'll have to overcome. As this appears to be an actual Engl schematic (I think), perhaps they really don't want people cloning their amps - even if it means making it more difficult for them to be serviced (although they may provide correct schematics to their authorized service agents).

Ray

I is very flawed. also missing are alot of smaller valued coupling caps that are connected in series to the larger .047mfd ones in alot of the schematics. these are what prevent their amps from sounding like fart machines, and what give them an aggressive edge. they arent't to different from an ADA MP1 topology wise, or some of bruce zinkey's designs like the fender prosonic. there are some user drawn, reverse engineered scheme's of some of these on the blue guitar site.

[Tiago]

Hello!
At some time ago, there was someone at the older ampage site trying to build a ENGL amp, and he had some problems. Even with some of the problems solved, I think the user that build that amp wasn't very satisfied with the sound of it, so he modified it to sound better, but it ended different from an ENGL.
So in my opinion, it's not a starter project.
In a Portuguese forum, there was a report of some people that builded an MADAMP Kit from Musikding.de, http://www.musikding.de/index.php?cPath=103, and they were very satisfied with it. Its a starter project, it's well priced, and has a high gain channel. Altough, they were 15W amps, but keep in mind that a 100W amp wont sound two times louder than a 50W, but will sound two times louder than a 10Watt, at least in theory.
Good luck!

[blackwood]

oh God, I just love messed up schematics:mad:

here's where I found this one: http://www.englampsusa.com/products.asp?sku=E625

the thing is, I don't have enough money to first build a little fart-machine to try it out, then build a slightly bigger fart-machine etc.:D I may not know all the theory and math behind each and every stage - to design an amp, but I can put it together if I have a proper schematic.. the first thing I built was a 2-chanell 100W solid-state and it worked perfect, so.. I pretty much need a good schem. and I know I can put it together..

I looked at other amps like Fender, Marshall, Vox etc. and this looked kinda different but I didn't realize it's such a mess!!??

Can this be redesigned somehow or is it just a worthless piece of.... junk?
I'll check the Blue Guitar site.

I don't need a ton of gain and stuff, what I really like here is the clean sound. I've heard some sound samples and I had a chance to play on some other Engl models, so that's why I'd like to build it. The lead channel is nice too, it's just not my primary concern.

[blackwood]

Here's what I found at Blue Guitar. (attachment)

[Tiago]

Hello again,
well, that schematic is not accurate also. It hasn't cathode bypass caps. But it seems more accurate on the interstage coupling/tone shapping capacitors. Even if you get complete and accurate schematic, I still not recomend you to build an ENGL, at least for a first project.
Now that I know that you want is a really good clean channel, I recommend you a Fender. When I think about clean, I think Fender, and lots of Fender seem simple to build (simpler than a ENGL!!). After you have an amp working with a clean channel, then you can start thinking about adding a dirty channel.
Which Fender amp to build, I don't know, Fender is not my type of amp...but sure someone here can give you his opinion.
Good Luck!

[Leka]

Hello!
At some time ago, there was someone at the older ampage site trying to build a ENGL amp, and he had some problems. Even with some of the problems solved, I think the user that build that amp wasn't very satisfied with the sound of it, so he modified it to sound better, but it ended different from an ENGL.

Someone remembers my struggle!!? :)

It was me who built the Engl Blackmore clone and it did end up quite a lot different from an Engl - as you also remembered.
It did have huge oscillation problems, this schematics looks a lot the same with same faults in it. It is far from complete scematics. I had a hell of a struggle and thanks to Ray I got it fixed and even better!!
The amp nowadays has its unique sound - everyone has Engl nowadays.

Here are the old pages (in finnish), from the start of the project - a lot has happened since and I got lazy - haven't been updating these pages anymore...
www.kanetti.fi/~speedking/

Take my word, it's not worth the trouble - there are lots of easier projects available.
It took me three months just to get the oscillation out of the box. :rolleyes:

- Leka

p.s. My friend just bought an Engl Thunder combo and I'm _really_ tempted to see how it's built in real life...

[Joe N]

Here's what I found at Blue Guitar. (attachment)

I believe there is a screamer 50 on there too. as stated, the lower value caps look more correct, and I believe that the CK bypass cap values that you see on the other schemes will work fine being that there is quite a bit of bass roll-off from the smaller coupling caps. I would try something else before any of these though, you will end up spending more money trying to build it than if you just bought one or bought one used.

[SysCrusher]

You will not find a correct schematic out there for these things. They are all full of mistakes. I've built a high gainer very much like the powerball and from my experience, it's not an easy project. The schematics do give you a basic idea but without some knowledge of tube amps and some basic electronics, your not going to have an easy time. It's not a simple copy and paste and it works.BUT I do know where all those mistakes are and what will work.

[Leka]

You will not find a correct schematic out there for these things. They are all full of mistakes. I've built a high gainer very much like the powerball and from my experience, it's not an easy project. The schematics do give you a basic idea but without some knowledge of tube amps and some basic electronics, your not going to have an easy time. It's not a simple copy and paste and it works.BUT I do know where all those mistakes are and what will work.

Interesting, could you tell what are the main faults in these engl schematics?
What I would assume, a lot of small caps are missing?
As you might know from above I built an Engl (Blackmore) and in my build cathode caps are definately a lot smaller on the first stages.
I can't understand the idea of first putting huge bypass cathode cap and after that roll off the bass?

Please share your information, I got curious.

-Leka

[SysCrusher]

Interesting, could you tell what are the main faults in these engl schematics?
What I would assume, a lot of small caps are missing?
As you might know from above I built an Engl (Blackmore) and in my build cathode caps are definately a lot smaller on the first stages.
I can't understand the idea of first putting huge bypass cathode cap and after that roll off the bass?

Please share your information, I got curious.

-Leka


Hello Leka,
I remember seeing your build which turned out to be an excellent build. You pretty much just covered all the mistakes in your post. Except maybe the coupling caps. They should start out small somewhere around .001 uf, then .002uf and then .02 uf for the next triode; adjust to taste. The clean channel shares a common first stage coupling cap (.047uf) in series with the lead and crunch channel coupling caps. The way the schematics are it would be awfully farty even with lower cathode caps. I don't understand the cathode caps either since the bass frequencies are rolled off quite a bit. I still get alot of that crushing bass and still be tight enough without sounding mushy. I ended up using 2.7uf on mine. There is a few grid leak resistors missing as well as some values being incorrect. The snubber cap is in the wrong place/wrong value in a few schematics I seen. The plate resistors seem to be ok as also the cathode resistors. I still question the grid bias resistors for the power amp though. I don't feel comfortable with them being 330k. Most of the mistakes seem to be in the preamp section before the tone stack which would be the bulk of the sound with these amps. With that said, the blackmore schematics seem to more correct out of all of them.

Also I used the standard choke for a twin in mine and never tried it without it; Could be some of that engl sound there as well. I never tried an engl in person so I can't comment on the sound other than sound clips I have heard.

Here's a clip from sending ideas back and forth with my brother, sounds to much like Diamond head though. I used a set of bright sounding C12N's. Could use a little less treble, I grabbed the Gibson V with emg's and forgot to adjust for the treble bite they have. It's a quick take with a flat EQ.

http://home.comcast.net/~jayjay67/headache.mp3

Amazing how much speakers change the sound. Weber Michigans sound good too, more mids with a huge bottom end. Thinking about going for a set of G12T-75 or Eminence Man O War. I love to compare notes with you Leka. I could go into more details about my experience and what I have learned with this type of amp. Got to go for now, wife is feeling ill.

Cheers
Jay

[Joe N]

Interesting, could you tell what are the main faults in these engl schematics?
What I would assume, a lot of small caps are missing?
As you might know from above I built an Engl (Blackmore) and in my build cathode caps are definately a lot smaller on the first stages.
I can't understand the idea of first putting huge bypass cathode cap and after that roll off the bass?

Please share your information, I got curious.

-Leka

the reason why they would use such a large cap, and then roll off the bass could be one of two things as far as I'm concerned.

1). cost of manufacturing is probably the most likely reason. It is alot cheaper for a company to buy 20000 25uf/50v capacitors than it is for a company to buy 10 .68uf's 12 2.2uf's 5 .47uf's 100 1uf's etc...thats also the reason why you see alot of .047uf coupling caps and other reoccuring values in those schemes, and in most company's schemes.

2). while you can set the same -3db knee with the Ck, as you can with the coupling capacitor, the coupling capacitor has a steeper roll off.

I have never played a real Engl, but they look like they sound like an ADA MP1. the topology is really similar.

[Leka]

Here's a clip from sending ideas back and forth with my brother, sounds to much like Diamond head though. I used a set of bright sounding C12N's. Could use a little less treble, I grabbed the Gibson V with emg's and forgot to adjust for the treble bite they have. It's a quick take with a flat EQ.

http://home.comcast.net/~jayjay67/headache.mp3

Amazing how much speakers change the sound. Weber Michigans sound good too, more mids with a huge bottom end. Thinking about going for a set of G12T-75 or Eminence Man O War. I love to compare notes with you Leka. I could go into more details about my experience and what I have learned with this type of amp. Got to go for now, wife is feeling ill.

Cheers
Jay

Hi Jay!

Hope your wife's feeling better now!
Thank you for sharing the info, I have also an Hammond choke in my build.
Your sound clip was really nice!! Really respectable sound! :)
Here are two small clips of my build, played with a -87 Tokai with its original humbucker / one Celestion Vintage 30 speaker, recorded with one shure 58 beta.
These are also quick takes with just a small distortion to make some rock music. :)

demo1.mp3 (http://www.kanetti.fi/~speedking/m_demo1.mp3)
demo2.mp3 (http://www.kanetti.fi/~speedking/m_demo2.mp3)

Cheers,

-Leka

[SysCrusher]

Hi Jay!

Hope your wife's feeling better now!
Thank you for sharing the info, I have also an Hammond choke in my build.
Your sound clip was really nice!! Really respectable sound! :)
Here are two small clips of my build, played with a -87 Tokai with its original humbucker / one Celestion Vintage 30 speaker, recorded with one shure 58 beta.
These are also quick takes with just a small distortion to make some rock music. :)

demo1.mp3 (http://www.kanetti.fi/~speedking/m_demo1.mp3)
demo2.mp3 (http://www.kanetti.fi/~speedking/m_demo2.mp3)

Cheers,

-Leka



Wow, that sounds really good Leka! Sounds more defined then the last time I heard your amp. That Vintage 30 really gives it a thick tone. I think I'll have to reconsider the Vintage 30 for my build. How well did the cleans come out for you? I had an extra triode left so i dedicated that to my clean channel so the clean channel is completely separate from my distorted channel. Thank you for you condolence, my Wife is doing fine. Seems to be just the normal allergies. When she is quiet, not bothering me to do something, then I need to worry. :D

[Leka]

Wow, that sounds really good Leka! Sounds more defined then the last time I heard your amp. That Vintage 30 really gives it a thick tone. I think I'll have to reconsider the Vintage 30 for my build. How well did the cleans come out for you? I had an extra triode left so i dedicated that to my clean channel so the clean channel is completely separate from my distorted channel. Thank you for you condolence, my Wife is doing fine. Seems to be just the normal allergies. When she is quiet, not bothering me to do something, then I need to worry. :D

Hi Jay!

I'm glad you liked it! The clean side isn't _that_ good. It did get better by using separate coupling caps on clean / dist channel. (bigger cap for the clean channel)
However I still have a lot to learn and one thing I have noticed is that you should _always_ keep track on what changes you do to your amp. I don't have any idea (maybe some) of what was the setup in these two sound samples as I have done numerous of different experimentations to this amp during the last year...:cool:
It's sad because now when I heard these samples again, my amp sounded better then than now...:mad:
I am very pleased with the Vintage 30 speaker, you should try one!

I do have a problem with getting away from annoying mids which make it sound too "nosy".
Is it the best way to drop the middle-band in the eq-section?
Or shoud I try to expand the bass and treble before / after the eq?

Now when I'm having a "good" tone the mids knob is at nearly zero, bass at 10 and treble knob at about 3, from 0-10.

All the best,
-Leka

[R ski]

The diagrams look simular at the output section. The transformer
resistance will detirmined the bias of the output current The zener diode
is shunted out from what I assume as relay contacts

The power transformer multitap isn't clearly on the secondary taps.
The B+ is stepped up by a German multiplier circuitry.

A lot of build, kinda resembles MESA Boogie Mark 4 in some way.

[Joe N]

The diagrams look simular at the output section. The transformer
resistance will detirmined the bias of the output current The zener diode
is shunted out from what I assume as relay contacts

The power transformer multitap isn't clearly on the secondary taps.
The B+ is stepped up by a German multiplier circuitry.

A lot of build, kinda resembles MESA Boogie Mark 4 in some way.

from what I hear, they are not built that well, or at least in the cheaper models.

[SysCrusher]

Hi Jay!

I'm glad you liked it! The clean side isn't _that_ good. It did get better by using separate coupling caps on clean / dist channel. (bigger cap for the clean channel)
However I still have a lot to learn and one thing I have noticed is that you should _always_ keep track on what changes you do to your amp. I don't have any idea (maybe some) of what was the setup in these two sound samples as I have done numerous of different experimentations to this amp during the last year...:cool:
It's sad because now when I heard these samples again, my amp sounded better then than now...:mad:
I am very pleased with the Vintage 30 speaker, you should try one!

I do have a problem with getting away from annoying mids which make it sound too "nosy".
Is it the best way to drop the middle-band in the eq-section?
Or shoud I try to expand the bass and treble before / after the eq?

Now when I'm having a "good" tone the mids knob is at nearly zero, bass at 10 and treble knob at about 3, from 0-10.

All the best,
-Leka


I don't get that unless I want it too sound that way. My standard setting is, bass 10, mids 4, treble 7.5, presence at 3 - 6 depending on my mood. I have a depth control added to the nfb loop too and I set that at around 3. Sounds like you got alot of extra high mids and treble there.

If you build using the schematic, think about that 680pf treble cap. Also think about the mid and bass caps in the tone stack. The engl from what I see from the schematics, is that they use an extra 47nf coupling cap before the tonestack. That means the caps in the tone stack will be in series with that 47nf coupling cap. That means, the tone stack caps are really half that value. 47nf and 47nf in series is about 23.5nf. So your bass and mid cap is 23.5nf. If you want to get closer to a more Fender values, I would change that 47nf coupling cap to a 100nf and then change the bass cap to 1uf, mid cap to 100nf. Your going to get alot high mids and highs with that 680pf treble cap. I have that on a pull switch for a decent mid and high boost.

Personally I don't understand the 47nf snubber cap across the plate resistor for the effects loop send. That 47nf cap is 47,000pF killing all the high end. Can't be right. The powerball and the rest of the schematics have the same thing. Remove that cap if you got it. Add a 1nf cap across the 330k plate resistor for that cold clipping triode. That will sweeten up your treble and high mid response. I also added a .5nf cap from plate to cathode on each triode except that cold clipping triode. I think they sound better than passing highs to ground. A trick I coppied from Rivera. Those are my personal secrets that I think are a must have for these engl type circuits. The rest is just playing with the coupling caps, grid resistor and grid leak resistors in the preamp. Duncan Amps site has a decent excell spread sheet for the frequency cutoffs if you don't like the doing the math. A 47nf cap and a 220 grid leak resistor is around 15 Hz. Something to think about.

My opinion is to do all your frequency shaping or control before the eq section. Atleast leaving a decent enough frequency band to manipulate with the tone stack. Then the power amp and the effects loop can be configured for a nice wide band of frequencies.

Im with you about the clean side, not the beat but usable. I guess I love that Fender clean to much. Oh, look for ExpressSCH on the net. Cool little program for free. I use that to draw out my circuits and then update them every time I get that modding bug. Got to leave for now. Wife has a nice dinner going.

Cheers
Jay

[Leka]

I don't get that unless I want it too sound that way. My standard setting is, bass 10, mids 4, treble 7.5, presence at 3 - 6 depending on my mood. I have a depth control added to the nfb loop too and I set that at around 3. Sounds like you got alot of extra high mids and treble there.

If you build using the schematic, think about that 680pf treble cap. Also think about the mid and bass caps in the tone stack. The engl from what I see from the schematics, is that they use an extra 47nf coupling cap before the tonestack. That means the caps in the tone stack will be in series with that 47nf coupling cap. That means, the tone stack caps are really half that value. 47nf and 47nf in series is about 23.5nf. So your bass and mid cap is 23.5nf. If you want to get closer to a more Fender values, I would change that 47nf coupling cap to a 100nf and then change the bass cap to 1uf, mid cap to 100nf. Your going to get alot high mids and highs with that 680pf treble cap. I have that on a pull switch for a decent mid and high boost.

Personally I don't understand the 47nf snubber cap across the plate resistor for the effects loop send. That 47nf cap is 47,000pF killing all the high end. Can't be right. The powerball and the rest of the schematics have the same thing. Remove that cap if you got it. Add a 1nf cap across the 330k plate resistor for that cold clipping triode. That will sweeten up your treble and high mid response. I also added a .5nf cap from plate to cathode on each triode except that cold clipping triode. I think they sound better than passing highs to ground. A trick I coppied from Rivera. Those are my personal secrets that I think are a must have for these engl type circuits. The rest is just playing with the coupling caps, grid resistor and grid leak resistors in the preamp. Duncan Amps site has a decent excell spread sheet for the frequency cutoffs if you don't like the doing the math. A 47nf cap and a 220 grid leak resistor is around 15 Hz. Something to think about.

My opinion is to do all your frequency shaping or control before the eq section. Atleast leaving a decent enough frequency band to manipulate with the tone stack. Then the power amp and the effects loop can be configured for a nice wide band of frequencies.

Im with you about the clean side, not the beat but usable. I guess I love that Fender clean to much. Oh, look for ExpressSCH on the net. Cool little program for free. I use that to draw out my circuits and then update them every time I get that modding bug. Got to leave for now. Wife has a nice dinner going.

Cheers
Jay

Hi Jay!

Thank you a lot for the tips! Now I know what to do next and which part will be modified again...:)
I did have the large snubber cap already replaced. The Rivera trick I have to try! Rivera is a nice looking amp but I've never seen one here in Finland...
I've been using Orcad for drawing the schematics but I've been too lazy to update it. I will do it next before I mess up further the circuit...
I got permission from my friend to tear down his Engl and see how it's done. (If I get it back again... :) )
I certainly will do it to see how they are done in real life.
I think the Engl-amps have quite nice sound, but could be also better with some mods...;)

Cheers,
Leka