Quote from: Zappacat on July 07, 2009, 11:19:02 PM
I'm planning on building an 18watt clone.  Already have the transformers and turret board.  If I built a head unit could I utilize this same type of setup?  Basically i'd be using a resistor circuit some way to bring the 18 watt heads CRANKED UP output down to line level and then sending that line level signal to a solid state amplifier?

What if I wanted to use something like a POD XT for effects?  Where should it go in the signal chain using your preferred signal path?

I really like the idea that you've presented here.  I'm on a REAL tight budget right now.  If I don't have to shell out a lot of cash for some vintage speakers on the 18 watt setup I'd like to run the output of it into something solid state as you describe.  I guess the solid state amp should be something that doesn't color the sound much.  Could I use that tone stack of yours after the attenuated line level signal of the 18 watt and send that into one of these home built chip amps based off of LM386 or something like that?  What do you suggest for solid state power amp + speakers?

Sorry about all the questions.


Thanks Phil

Hello Zappacat, all is well with questions,,, taken my pills :loco
Basically try every option till you find what works with the gear you have.
Keep in mind everyone has different ideas of what constitutes great tone.

If you want to save a lot of pain drop the efx till you *Nail a good Rock tone*,,Pretty much all the other tones stem from that basic tonality.
I've simply discovered an easy and cheap way to develop most of the tones that are usually sort after without the need to buy out the fender factory.

Chip Amps ?

I just recently fixed a mates Trademark60 (Tech21) Although he was very impressed as I had swapped the overly harsh original speaker it came with for something a little more civilised giving the amp a lot more warmth.
I then made the mistake of plugging my ReAmp rig into the Return jack of his Trademark 60 Amp bypassing all the preamp stages only using his powerstage and speaker and he almost wet himself with excitment,,
The Trademark uses an LM3876 chip powerstage,,, so there you go,, Even with all the (covered in Goob) secret circuitry that lurks inside Tech 21 preamps it can't compete with the Reamp system. A fair test as the power chip and speaker where the same.
Now He wants a Reamp setup built like yesterday.

As to other power chips;
remember they are ALL DC Amps and By Design these are ALL made to have a DEAD Flat Response anyway so there is very little difference except for power I guess.
You can change the bottom end rolloff via external Cap selection but that's about it.

Getting tecky;
              The LM3876 power Transistors are all NPN and that maybe rather old hat design.
From what I've read an N and P channel device would work better. But hey it sounded ok.
All that stuff is to deep for me ,, others here will be better qualified to comment in depth.
------

Ok Re the signal path;
I've found the PhAbbTone FIRST seems to work best then > OD box > Tube amp > Soak to line > Efx here if I use them > Graphic> SState powerstage.

Cut the mid on the PhAbbTone (if your taking note,, you will know that's cutting at about 400Hz.) Then it's tilted towards the treble > tube amp > Graphic up at 100Hz, big cut at 1000Hz, then up again at 2/3kHz, past 5kHz not much happens.

This works well through my tube Amp so as you can hopefully understand with a big ultra bright tube amp it would all need a rethink.
Think long and hard about it before you build the tube amp as most HotRod tube amp info assumes it's driving a speaker directly but I found no use for *Multipule preamp triode stages*, In fact it's debateable whether triode preamp distortion sounds any different/better than SState circuits. Remember you want to hear the power tubes not preamp fizz.

If it helps,, My tube amp is only average by itself (an old slightly dark, almost muddy plain tubeamp from a bygone era) but it has the dynamic response that can't be done easily via SState. the rest is My PhAbbTone box,, Crunch box,, and Graphic after the tube amp.
If you think that you have to perfect the tube amp tone FIRST then you waste a lot of solder trying to perfect it.
BTDT,, yuk never again. All the slick tone tweaks stuff can be done outside of a simple tube amplifier.
My tube amp is really just a big oversized compressor.

BTW, go back to the second post here and read the link to Amptone page it will save me a lot of writing. Hopefully that will help shed light on what is often made to seem extremely complex. 90% of all that a guitar player needs to know about what goes on inside guitar amps is about *Tone Shaping* not Exotic Components soaked in snake oil,,,
Just put the Right EQ shapes at the right places in the signal chain and,,, presto.
------
I should mention the *Ground Lift* as anytime you join two chunks of Grounded gear together you will run into the dreaded ground loop hum issue. My guitar player brain can't cover every senerio so having the Ground Lift switch will Hopefully resolve most problems with ground loops. It's probably more pro to use an Isolation transformer but you will
need to use a good audio type and they are not cheap. I've opted for the poormans alternative which is at least SAFE.

And in case you or others get crazy ideas; Don't cut the earth plug to one Amplifier to kill the loop hum!
yes it works extremly well at killing hum,,,,And When your *DEAD* there is no hum. 0:)

I think if we continue it might be better to start a new post, as this is getting away from *pelanj* questions.
Cheers, Phil.

Quote from: pelanj on March 15, 2009, 11:28:04 AM
Just a small point - not only push-pull pentodes, but single ended pentodes/triodes provide the tube feel as well (all the small tube combos out there). I think an ECL86 or ECC81 power amp should be sufficient and hope to try out soon.

The Dr.Boogey pedal looks nice - I might try one later as I have a bunch of distortion pedals with quite nice sound if used with a tube amp.

Just be aware that SE output generally don't quite work as the PI section seems to be part of the sound/tone, If I remember correctly Guy Kendrik even mentions it on his site.

But yes by all means try it.

Silly me I've just realised that I missed your reply,, till now

I should (when I get time) post my whole blab with schematics under Hybrids as this is deviating from your content. Thanks, Phil.

Sorry you feel that way
Search box is over here >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Sadly the world of audio electronics is a very slow process and some ok I lied,, A Lot of patience is manditory I'm afraid.

There are some really good people here and if you brouse through I'm quite sure you will find something that is loud enough for your tonal requirments. 8|

Have fun, phattum Phil.

Quote from: Zappacat on July 06, 2009, 12:00:22 PM

Quote
I personally use a 10 Watt tube power stage in my ReAmp setup
which is loosly based on the Guytron GT100 concept.

My Signal path goes like this;
Tone box > OD circuit > 10watt PP TubeAmp > Soak/Spk-to-Line > Graphic Eq >
120Watt SState PwrAmp > 15inch speaker (sealed back)
(the first 4 are all home brew gear.)

Can you tell me what you mean by "Soak/Spk-to-Line"  Thanks!

Hey Zappacat,
                    Just a big resistor (instead of speaker) to soak up the tube power stage, then a voltage division to give you a line level output so that you can Re EQ it all and send it onto another amp of much larger power rating. Hence I call it a *ReAmp System*.

This captures the power tube compression effect which if you care to think about it for long enough is what all those fancy pedals are desperatly trying to *Emulate*.
Ouch!    Can I say that here?
The Tube Power stage is the most dynamic part of a tube amp so that's what you really need if you want great dynamic guitar sound. This enables you to pull all those tones you've never been able to get without deafening everyone.
Any OD you want at Any SPL you so wish.
Even my ten watt tube amp straight to a speaker is to Loud for practice.
This idea was obviously good enough for Eddie VH,,, so I'm happy with that.

There are many ways to do the same or similar thing but I've found this way is the cheapest to impliment and being modular you can interchange a lot of different gear,, experimenters dream for me.

Most attenuators (which is how mine basicly works) Destroy the tone if you try to drive the speaker directly from the attenuated signal and most folks (including some experts) tend to leave it alone or go the other way and turn it into an overly complex box of tricks (resorting to light bulbs amoung other things) but fail to realise you can just tap the simple resistive load ,,eq it, time based efx and many more things to it and simply reamplify it all.  Heck that's what basically happens in a Recording Studio anyway and they seem to sell a lot of records and no one even blinks.

Some tone geeks forget that most players are trying to *Emulate a Pre Recorded Sound/Tone* as that's how most of us hear things and the sound is often coloured anyway.
If you where standing in the studio when the Actual Recording was taken,
then 9 times out of ten your brain would have heard a completly different sound/tone.
Even the best of mic's add there own colour.

I'm adding my load box schematic for you,, give some ideas to work with.
The boost is just a level shift,,, a nice little add-on with no complicated relay.
Just make sure the Main load resistor is Bigger than the wattage from your tube amp.
ie, 10 watt amp use 20 to 30 watt resistor,, no need to run things to hot.

Be warned some tube amps today have utterly stupid HT voltages way beyond what is really safe so make sure you know the amp or derate it's HT via the VVR you mentioned.
My tube amp is home built useing only 240Volt HT.
I could bump it up to some stupid voltage like 360Volts but this does nothing to improve the tone/dynamics. Fact is the power tube compression works better running on lower HT anyway, so a win win.
Have fun,, Phil.

Oh dear,, the tube amp Bug has bitten you ay?,,, have fun.

1st answer;
YES,, absolutly any of those tree type tone stacks can be used in just about any tube amp.
I have no doubt that HiWatt will give a bigger mid cut than the others.
with the mid *full off* there might be a smidge less gain in the amp.

I opted to chuck tone stacks in tube amps because they just waste triode voltage gain,,, that's why I built the PhAbb Tone box, it just simplifiys a whole lot of hassels.  ie, I can use any amp and get the same tonal signiture happening,,,, whereas if you wack a tone stack in a tube amp you can only get that tone with That particular Amp.

I only have 4 Valves in my rig,, it's very much like a Fender Pro Junior.
Volume and tone cut knobs only.

ALL the rest is done via SSate gear.
http://www.ssguitar.com/index.php?topic=1064.msg6521#msg6521
Read 4th post on this page for a more complete coverage of how my ReAmp System works.

The VVR thing works but I've found this to be more rewarding as you can do some Very slick post power amp tweaks.
Any tone within reason I spose,, at any SPL I wish to dial in.
Cheers,, Phil.

Not sure what the problem is?

Here is how it would work in my mind,
Your preamp> Tone stack *(with it's own dedicated gain block)* then a true bypass switching arangement so the tone circuit With it's OWN gain block is either *In or Out* of circuit.
>> then onto the rest of the circuit.

Though my schematic does not show the true bypass switch it is used to do exactly as I've just explained.
I'm quite sure there are other ways to do what you're trying to do but I've not found one that is as straight forward and as simple to impliment as the mechanical bypass.

I just set the gain trim on my tone circuit so that the *on state and bypass state* are at the same level.
Hope you sort it out,, Phil.

Quote from: Ripthorn on June 29, 2009, 10:38:36 AM
Thanks for the replies, guys.  I am using a TL072 (one half of it) with 12V supply.  Your circuit looks good, Phil, I might have to give that a go.  I just hope I'm not slamming the opamp input.

Not sure if you are you referring to *Your Opamp*or *My Opamp* ?

The tone stack (like most of them) sucks up about 60 to 70% of the signal swing,,,
ie, 1 Volt input comes out about 300mV on the treble wiper,Then through the Active buffer and gain section which pulls it back up.
If you are running this from a 9 volt cell then the output can only get to about 6-7volts no matter how big the input swing.
One not so obvious advantage of having a *passive input* tone stack is the input signal can be larger than the supply rail for the opamp and still come out clean,, (as long as the incoming signal is not already distorted of course)
Contry to common practice I actually put my tone box *FIRST* in the signal chain but it will work after other gear as well,, depends on what gear you already have.
One chap who uses one of my tone boxes has a maze of floor pedals and he also has found it better at the front end.
Oh and don't make the mistake of trying to up the gain,, use dedicated pedals for that.
Have fun,, Phil.

Hi Ripthorn,
                Try turning the whole idea around the other way,, you will have much more success that way.

Have a looksee at my tone stack as it does exactly what you are asking,,
ie, When the tone is *bypassed* there is NO Gain.  All the gain is engaged only when the tone stack is ON.
http://www.ssguitar.com/index.php?topic=1136.0

The volume is really just a gain trim so you can attain a good balance between the on and bypass levels.
BTW you will have a darn hard time trying to get distortion out of my circuit,, it runs super clean.
Have fun, Phil.

Quote from: troublerat on June 17, 2009, 12:33:55 AM
Forgive me for being a little thick on this thermal grease /heat sink thing. What we want is to pass the heat from chip to the heat sink but not the electrical characteristics of the chip itself. With an + - power supply. The pos volt connected to the pos. pin the neg. volt connected to the neg pin. The surface of the chip and heat sink are the grnd ?

Hi troublerat,
                  NO That would be a very bad assumption!
You do get chips that are "Case Ground" but most are NOT.

Heat sinking is not hard to get your head around just think BIG and FAT,
You don't even need the fins in some cases,, The Thickness of *Where* the chip mounts is the important thing, not the fancy fins.
That Chip/Power Transistor whatever has to get rid of excess heat instantly and the only way to do that is to have Alloy with some girth/Mass (thickness) right there next to it.  Fancy Finns help but more often than not they just look pretty.

To get some idea of what goes on look at the heatsinks on computer chips,,, some actually come with a *Copper* centre!! Yes the Copper pulls the heat out faster than alloy.  Then the alloy,,,, Then the fancy finns, then the fancy Fans.

I use  a 6mm thick Alloy Angle plate 100 x 100mm by 200mm long (with no fins) 
Dissapating a 50 watt amp and it is only ever warm.

A rule of thumb I use is if the alloy is *to hot to touch for more than 1 sec* then your in trouble.  though some pro gear runs this hot it's far from ideal.
Phil.

 Hello johnboypitt,

You are obviously going through a shop ,, Ask if you can get the phone num of the repair guy and talk directly to him.
Explain what you just stated here and you might get much better service/advice.
If the Amp is not really worth fixing he will probably tell you straight up.
Remember Unless you talk direct your Amp is just another job number from the shop.
Hope it pans out for you,, Phil.

Hi 1way,
Yes just make a small audio lead up and plug it into any line input or other similar equipment.
Old Tape recorders/Ghetto blasters come in handy for things like this. 8|

If no go, check you have DC on the power pins of the opamp,, Pin4 = Neg 
Pin8 =Pos
Cheers Phil.

Quote from: iceregent on June 14, 2009, 01:32:11 AM
Ok, not sure what kinda pics you are talking of, but I took pictures of the main input/power supply pcb so far, and they are at: http://amp.iceregent.com. I am working on getting the 60 watt bulb setup, simple to wire in a lamp with a 60 watt bulb in series with a plug. If I need clearer pictures or different pictures please let me know.

Ice

Again,,, most likely a dud Electro Cap, the big black ones.
FIRST,, Establish you have both AC (Before any Rectification)
and then,,,,,,, DC (without Caps)

Your transformer has 3 AC wires. (Or/Blueygreen/Or)
The greeny blue one is the centre TAP (zero volts from there onwards)

Pull all 4 terminals from Bridge Rect. (Crist sakes mark them first!)

Now set meter for AC Max reading,
Neg probe to ZERO blueygreen center tap,,now read the AC volts of BOTH Orange wires.
Should both read the same AC voltage if one side is way off the power transfomer is stuffed,,unlikely.

Next set Meter to DC reading.
Re-install AC (orange wires) from transfomer onto the bridge rect.
(Don't connect the DC wires that go to Caps yet)

Now power up again and read the DC on the Bridge terminals.
One is a postive voltage the other is negitive.
(again Neg probe to ZERO blueygreen center tap)
These should be within a volt of each other, don't expect to be exact.

Now reconnect the Caps and see what readings you get,,one side will likely be down a fair bit.       
But I would just replace both CAPS First and be safe.

I've added some hints on this pic for you..
Now One word of warning those black and white wires are close to where you're working and they look to be mains wires so be carefull

Remember the DC reading goes up x 1.414 after you add the Capacitors.
Hope you fix it.  Phil.

Quote from: J M Fahey on June 10, 2009, 11:28:09 AM
Hi Phatt, thanks, I´ll give it a try.
So far I´ve been using the "old method", you know, with soldering irons that burn you deep if you grab them the wrong way, components that burn, smoke, crack, etc.
I think it will be a way of saving some $$$ and also uttering wild expeletives such as: "!@#º$%&/()=?¿\|"  :duh :trouble :grr .
Bye.
J M Fahey

Oh Yes all of that is what I wanted to avoid,, so I'm in love.<3)
From reading some of your posts I doubt you will trouble finding your way around.
I used the word *cheat* because I do realise that to do this in the good old days required a lot of maths and geometry skill.
So I feel somewhat privelidged to be able to press a button and Bingo, have it all done in the blink of an eye.
You can't help but respect those folks who burnt out pincils and brains to plot a curve.

The thing that really struck me about plotting amplifiers in general was the very different way SS and Valves work. SS is kinda a dead flat response whereas tubes are very specific in there response curves.
Though you can make tube gear HiFi flat but they don't sound good then.

In the end I had one of those enlightening moments and kinda realised that the whole game is about the tone curves ,, one response running into another,, to my limited mind this makes sense and from that any guitar player like *ME* can at least start to grasp the idea of tonal manipulation. The marshall simulation trick found on JTM 30/60 Marshall Amps is a classic example of how to go about reproducing specific tones.
From what I've read Teck21 use similar circuit tricks to capture the tonal signiture of certain amps.
Have fun,, Phil.

Oh dear,, Likely something else died when the filter went.
You still may have a power supply issue,,
the highest voltages are on those big Caps  but the preamp needs much smaller volts
from the main supply.

Without seeing the amp it's hard to know as there are many ways to derive the preamp supplies. Some just use resistors and zener diodes for regulation while some have dedicated chips to do it.

If the amp is out of box and nothing is melting/glowing/smoking while it's on then,,,
IF it has chips with 8 pins then you can check pins 4 and 8 on those chips.

usually these run on a split supply,,ie, up too 15/0/15 VDC
Pin 4 should read a *Negitive voltage* and pin 8 a *Positive reading*.

Normally these are very close to the same reading ie you should read something like this; Pin 8= 14.9 pos and Pin 4= 15.1 neg, with respect to ground.
If one or both of those voltages are way off then it's certainly a supply issue again.

Everthing may have been restored in the supply dept but the original fault might have killed one of the chips and that may not be as easy to track down.

If you're good at back engineering circuits then disconnect the preamp supply and see what reading you get.
Some circuits are easy but a lot of modern ones are just nightmares to work out.
Cheers, Phil.

At a guess, Main Filter Capacitors on the power supply.
Usually two in SS amps  and usually the biggest ones in the amp.
Sorry that's all I can do with the info. Cheers Phil.