Stereo combo amp for use with POD?

[Zappacat]

I'd like to build a combo 2x12 stereo amp that has balanced stereo sends(to send to the PA).  It doesn't need much(if anything) on it for a tone stack.  The more power the better.  It just needs to be uncolored sound.  I guess what I'm looking to build is very similar to a stereo Tech 21 power engine.  Could any of you point me in the right direction.  I'd really appreciate it.

I'm seriously considering trying this amplifier http://sound.westhost.com/project27.htm 100W Guitar Amplifier Mk II.  Have any of you built this amp?  The only thing I see that it lacks is stereo.  Outside of that it seems to be well documented and I like the way he explained it.

[joecool85]

I'd like to build a combo 2x12 stereo amp that has balanced stereo sends(to send to the PA).  It doesn't need much(if anything) on it for a tone stack.  The more power the better.  It just needs to be uncolored sound.  I guess what I'm looking to build is very similar to a stereo Tech 21 power engine.  Could any of you point me in the right direction.  I'd really appreciate it.

I'm seriously considering trying this amplifier http://sound.westhost.com/project27.htm 100W Guitar Amplifier Mk II.  Have any of you built this amp?  The only thing I see that it lacks is stereo.  Outside of that it seems to be well documented and I like the way he explained it.

The more power the better?  How about 240w RMS?  Build a stereo amp with two LM4780 chips in bridged mode (they're built for stereo use), easy to build, tons of power.  If that's too much power for you, a single LM4780 will yield half the power.  Plan on having a nice big heat sink whatever you do

[Dylan]

I'd like to build a combo 2x12 stereo amp that has balanced stereo sends(to send to the PA).  It doesn't need much(if anything) on it for a tone stack.  The more power the better.  It just needs to be uncolored sound.  I guess what I'm looking to build is very similar to a stereo Tech 21 power engine.  Could any of you point me in the right direction.  I'd really appreciate it.

I'm seriously considering trying this amplifier http://sound.westhost.com/project27.htm 100W Guitar Amplifier Mk II.  Have any of you built this amp?  The only thing I see that it lacks is stereo.  Outside of that it seems to be well documented and I like the way he explained it.

The more power the better?  How about 240w RMS?  Build a stereo amp with two LM4780 chips in bridged mode (they're built for stereo use), easy to build, tons of power.  If that's too much power for you, a single LM4780 will yield half the power.  Plan on having a nice big heat sink whatever you do

yep!

[phatt]

Hi Zappacat,
         Try this one instead http://sound.westhost.com/project101.htm

Probably eaiser to build,, a Ton more grunt (depending on PSu Voltage used)

The hidden bonus for this one is it will run on just about any voltage all the way up to 70/0/70 VDC rails where it will output over 200watts into 8ohms.
I have not built one but it certainly looks like it would deliver the super clean flat response,, if that's what you want?

Also as you want stereo the price may climb quickly so have you considered some old HiFi poweramp sections they might be worth a look you may even be able to use some of the line inputs and save yourself a lot of work.
You can pick up old 70's hifi amps cheap where I live.
Cheers, Phil.

[Zappacat]

Hi Zappacat,
         Try this one instead http://sound.westhost.com/project101.htm

Probably eaiser to build,, a Ton more grunt (depending on PSu Voltage used)

The hidden bonus for this one is it will run on just about any voltage all the way up to 70/0/70 VDC rails where it will output over 200watts into 8ohms.
I have not built one but it certainly looks like it would deliver the super clean flat response,, if that's what you want?

Also as you want stereo the price may climb quickly so have you considered some old HiFi poweramp sections they might be worth a look you may even be able to use some of the line inputs and save yourself a lot of work.
You can pick up old 70's hifi amps cheap where I live.
Cheers, Phil.

So, optimally I need to be looking for a good transformer that puts out 70/0/70 VDC.  Any other requirements on the power supply?

Since I'll be running 2 speakers, what ohm rating should I be looking for right now.  I was thinking about getting celestion seventy eighties since that's what they are putting in the power engines.  Any better ideas?

I'm going to build a 2x12 speaker cabinet to house the amplifier and speakers.  This lm4780 allow me to run in stereo right?  I want to send my Line6 POD signal to this box for playing live and practicing.  How big of a deal would it be for me to add a pair of balanced outputs so I can send my stereo signal to the sound board? 

I've seen serveral PCB board renditions on the net for sale but they are all designed for home stereo use.  I was tempted to build this whole thing on a breadboard at first but I've heard that the connections on the lm4780 are so small that you almost need a PCB for it to be able to access the indiviual circuit pins more easily.  I'd like for the amp to drive a pair of Celestion Seventy80's.  Would I need to be using two lm4780s to effectively drive them?  What kind of speakers do you guys suggest for this application?  What ohm ratings and wattages?  Any help greatly appreciated.

While constructing the speaker cabinet should I angle them out from the center a little bit to get more stereo separation?  I've seen that idea employed in some stereo cabinets and not in others.  What are your opinions on this?

Thanks for the help guys!

[J M Fahey]

Hi Zappacat.
You seem to be posting practically the same questions on two different threads, at the same time.
It sure gets confusing, and difficult to follow.
Thanks.

[Zappacat]

Hi Zappacat.
You seem to be posting practically the same questions on two different threads, at the same time.
It sure gets confusing, and difficult to follow.
Thanks.

Sorry, I didn't plan it that way.  I found the Tech 21 topic after posting this topic.  You'll notice when I first got involved with the other topic I stated that in the discourse of conversation.

[phatt]

Hello Zappacat,
                     Hey alot of Q's there!
I think you need to get some ideas nailed down first and kinda stick to one thing at a time,, kool?
Re the LM 4780 chip Q.
You can simply look up the specs for that and it will be obvious if it is stereo or not.
----
Two of those proj 101 Amps will make your ears bleed my friend and you will need at least two quad boxes to make use of all that power. Anyway the cost of the PSU at 100VAC-CTap tranny will scare you!   oh and YOU have to carry it also.
I only mentioned it because even at 40/0/40 VDC it will still have ample power.
----
If you want balanced outputs to send to a desk then I don't get it.
You wish to DI a 400watt Amp to a PA desk,,, like what For :duh
----
If you don't know *most* SState PwrAmps can handle 4 OHMS minimum load.
Less than that and you are pushing your luck.
Read project 101 more slowly and absorb it,,,the Answer for that is on that page anyway.
----
Personally I never got the stereo trip as a good guitar sound with a little time effect and good EQ will sound far more convincing than any stereo pod.
I can do more tricks with my simple gear than most of those cab sims.
Sadly these days the player is judged more by how up-to-date his pedal board is than his ability to play good music. 
just my thoughts.

If I'm getting this right you really need two things,,,
1/ a stereo preamp (with bal outs).
2/ a Stereo poweramp.

BTW there is some bal circuit ideas on ESP site
Cheers, Phil.

[Zappacat]

Hello Zappacat,
                     Hey alot of Q's there!
I think you need to get some ideas nailed down first and kinda stick to one thing at a time,, kool?

I'll try to more precisely define what I'm looking for in the context of this message.

Re the LM 4780 chip Q.
You can simply look up the specs for that and it will be obvious if it is stereo or not.
----
Two of those proj 101 Amps will make your ears bleed my friend and you will need at least two quad boxes to make use of all that power. Anyway the cost of the PSU at 100VAC-CTap tranny will scare you!   oh and YOU have to carry it also.
I only mentioned it because even at 40/0/40 VDC it will still have ample power.

Well, I really don't need that much power.  I want the amp to drive two 12 inch speakers in stereo with enough wattage to play smaller venues.  I play keyboards as well.  It would be nice to use this setup for monitoring them onstage.  Right now I'm using a JBL Eon G2 15 that suits this purpose.  It would be nice to not HAVE to lug this thing around as well.

If you want balanced outputs to send to a desk then I don't get it.
You wish to DI a 400watt Amp to a PA desk,,, like what For :duh

Well, I want to send stereo line level out to the board :duh  Maybe I'm stupid and I'm using the wrong terminology.  I'll have to say that I've played at venues when I wish I had the option to flick a switch and send 400 watts to Mr. genius house soundman at the board.  This thread doesn't need to turn into a "why do you want to send a stereo signal to the board" thread.  I want the option of doing this.  If anybody wants to debate that then start another thread.  I want to have the ability to send my stereo signal to the board.  Having 400 watts isn't important just as long as I can hear myself on stage and that I don't get drowned out by little half-stack boy.

If you don't know *most* SState PwrAmps can handle 4 OHMS minimum load.
Less than that and you are pushing your luck.
Read project 101 more slowly and absorb it,,,the Answer for that is on that page anyway.

OK, I'll do that.  I still don't quite have this OHMs thing fully understood.

Personally I never got the stereo trip as a good guitar sound with a little time effect and good EQ will sound far more convincing than any stereo pod.

Really?  How much time have you actually spent using one?  A friend of mine has one of these http://tech21nyc.com/support/manuals/amps/Trademark120-OM.pdf connected to his POD XT Live.  Evey time he shows up at a practice or plays anywhere on stage it's not only the topic of conversations amongst the guitarists(in a good way) but he has to carry a stick with him to keep people away from trying to play it.  This combination of preamp(POD XT series) with the Tech21 Trademark 120 amp setup is amazing!  I'm not kidding you about this either.  I want to build something like this amp keeping the size/weight/cost to a minimum.  Maybe I should have been more clear about that before.  One of the best things is the ability to program your set lists using the Line6 software.  This way when you go to a gig it's an easy, quick setup.  The idea of building something like this is quite intriguing to me and I'm going to make it happen.

I can do more tricks with my simple gear than most of those cab sims.

You must be a LOT better at it than I am.

Sadly these days the player is judged more by how up-to-date his pedal board is than his ability to play good music.

By who?  Maybe you look at it that way but I don't.  I like to hear them first.  I'm not really too concerned about what people think about the equipment I'm using either.

If I'm getting this right you really need two things,,,
1/ a stereo preamp (with bal outs).
2/ a Stereo poweramp.

I already have a stereo preamp in the POD XT.  Stereo power amp = yes.  Also cost/weight/size are considerations.  It might be better for me to split the stereo signal before it hits the amp and send the POD signal direct to the board and the other signal to the amp.  I'm still debating this.  I think in a typical stage setup it would require less patching to run straight from the POD to the amp then amp to board.  This way I could toggle the amp input from guitar to keyboards without even more switching/cords.  Thanks for the input.

BTW there is some bal circuit ideas on ESP site
Cheers, Phil.

I'll check it out.  Thanks for the input Phil!

[phatt]

Ok Zappacat your obviously keen, an good on yah.

Unless I'm missing something I think you can save yourself a lot of time and money with a simple 4channel mixer that has a monitor out, They are cheap as chips these days.

Plug your pod into the first two ch's, paned L/R and send the stereo master out to your stage powerAmps, (which you wish to build).  Now just send the monitor output to FOH mix. The only drawback I can see with this is the mixer will only have a *mono* monitor out.
Anyway any soundman worth knowing will want a mono (preferably dry) signal.
You won't make many friends with serious sound guys if you want to do it your way. If you give him something he can use then he will go the extra mile to help you.
If you must have stereo, (Depending on the mixer) With a bit of thought you could use the effect send bus as well as the monitor bus to achieve another stereo signal out.
My thoughts on stereo,
Look I do understand the novelty of stereo guitar, It's fun but my advice is leave all that for the studio where it has merit. I would be more concerned about developing a good mono tone First.

Side note;
If you use the Eon 15 which I believe has a HF horn, ok might make your keys sound kool but this will just destroy guitar sound/tone. So if your using that for the guitar/pod system you gonna spend a lot of wasted time searching for the ultimate patch. I think you need to do some research on that.

I'll leave you with what I've gained over the years.
For guitar it is all about EQ. Sadly the pod type gizmos are ONLY the tip of what can be achieved.       Are they useful?
Yes absolutely but not as a stand alone One Box Answer to great tone.
You need to re EQ that as well, (This is super critical for success).
Well that's how I do it and partly that's how teck21 do it also, cept they kill it cause they missed the part where it says "Limit the Bandwidth".

My ideas are doable with the simplest of equipment, you do not need to spend a fortune to achieve great guitar tone.
Ultimate Guitar tone is a culmination of tone shapes imposed one into another.
The sentence is simple but developing a mental picture of what happens at every stage in that path takes years to sink in. (did for me, or maybe I'm just slow, wink)
It is interesting that the famous Sansamp is built into that Teck 120 you speak highly about.
The Sansamp worked because someone got the TONE shapes correct.
The darn problem with Teck21 gear (like a lot of SState gear) is they have miles to much bandwidth and they use high SPL speakers and the two together make it sound well crappy/clangorous.
Those special speakers where designed for **Tube Amps** where there is some use for extended range but this just screws up when driven by SState.
(a common SState oversight/stuffup)

Learn to nail down the tone shapes of all the famous tones and you will be well rewarded. Leaning the fundamentals of good solid rock tones are essential, only then do you add effects.
I don't want to dampen your Obvious Enthusiasm but judging from your posts there are things that you are missing you need some time to absorb and understand, hey it took me years.
It takes a lot of patience to read let alone understand.
Building pedals and basic stuff first is a good way to get your head around electronic gear.
Starting out building really complex stuff will make it ever so much harder for you.  (read as, stay away from complex mix circuits for now)
Believe me electronics is fun and addictive but my god you have to have a lot of patience,
ideally you need more patience than knowledge.
Cheers, Phil.

[Zappacat]

Thanks for all your input Phil,
   I can't tell you how much I appreciate your time taken to shed light on this subject matter.  I'm still taking my time to digest your first response.   I can deal with the mixer idea.  I have a Mackie 1202 VLZ pro that would fit that bill quite well.  What do you use for a live guitar rig setup?

Sincerely,
  Tom

[phatt]

Hi zappacat,
Before you run off and get yourself lost in a maze of wire. Try to undersand the CONCEPT first it'll save a lot of wasted wire. If I say the Answer to great tone is EQ/Dist/EQ/Dist/EQ/Dist/EQ/Dist.

You might laugh but if you mess with guitar amplification for long enough you start to realise from the earliest of tube design to latest digital gizmo your just tweaking the tone shape. Sure in fine detail it's a lot more complex but why make it hard as all the good stuff won't happen unless you get the basics right first.

Line up a dist unit and note the sound.(or try the pod if you wish)
Next insert a Parametric EQ *IN Front* and apply a deep mid notch at around 400/500 hz. If you don't have Para EQ or you have trouble with how they work just use a graphic type but para works best at this point.
You want a deep narrow notch CUT for best results otherwise you'll pull out to much.

Stick a graphic EQ *After* the dist unit and pull down at around 1khz. I very much doubt there is much need for me to carry on as it should all become rather obvious just how many different sounds can be achieved via this simple exercise.

(I'm posting this because the site is unavailable so I can't find exact address for the whole page)

Lifted from,  [http://www.amptone.com/index.html]
--------
True "secret" of amp tone - eq>dist and power attenuators
Home (amp tone and effects placement)

You can almost certainly get satisfactory sound from your existing decent tube amp,
without mods, by using, or at least experimenting with, the following  chain:
guitar
eq pedal
Comp/OD/Dist pedals
eq pedal
amp's preamp
amp's tone stack
amp's tube power amp
good power attenuator
amp's guitar speakers

The above is truly the "secret" of great amp tone.  Most postings, books,
and amp tone videos dwell on amp brands and mods and swapping tube types
and swapping speakers or pickups, but such priorities are backwards.
The real first order of business is knowing how to make the most of *any*
decent tube guitar amp.  It's a shame that most guitarists try all sorts
of things other than the secret weapon that gets straight to the point:
the eq>dist>eq pedal chain, which you can put before any guitar amp,
in conjunction with -- just as important at the other end of the chain --
some way of getting power-tube saturation independently of speaker volume,
and this amounts to the (unfortunately) "secret" of power attenuators.
-----------
End quote

My rig just takes this one step further and instead of attenuation I *reamplify* the tube power amp with another SState poweramp. Even without power tubes you can still make inroads to great tone.

This is the basic layout I use;
First a very simple DIY tone stack based on an old HiWatt circuit, SS
B> into a highly modified OD SS device
C> then a very simple tube amp which drives a resistive load
(like an attenuator cept No Speaker, you tap off a line level instead)
D> feed into an old HiFi graphic EQ
E> ultimatly driving a 120watt SS power Amp.

The tube amp is an old rewired Gramaphone from the 50's and only outputs 7watts,
no need for expensive tube gear here as you actually want a bad/cheap basic amp.
Heck it only has 1 volume and 1 tone knobs. All the rest can be done via SState.
Cheers, have fun, Phil.

[Zappacat]

Hi zappacat,
Before you run off and get yourself lost in a maze of wire. Try to undersand the CONCEPT first it'll save a lot of wasted wire. If I say the Answer to great tone is EQ/Dist/EQ/Dist/EQ/Dist/EQ/Dist.

You might laugh but if you mess with guitar amplification for long enough you start to realise from the earliest of tube design to latest digital gizmo your just tweaking the tone shape. Sure in fine detail it's a lot more complex but why make it hard as all the good stuff won't happen unless you get the basics right first.

Line up a dist unit and note the sound.(or try the pod if you wish)
Next insert a Parametric EQ *IN Front* and apply a deep mid notch at around 400/500 hz. If you don't have Para EQ or you have trouble with how they work just use a graphic type but para works best at this point.
You want a deep narrow notch CUT for best results otherwise you'll pull out to much.

Stick a graphic EQ *After* the dist unit and pull down at around 1khz. I very much doubt there is much need for me to carry on as it should all become rather obvious just how many different sounds can be achieved via this simple exercise.

(I'm posting this because the site is unavailable so I can't find exact address for the whole page)

Lifted from,  [http://www.amptone.com/index.html]
--------
True "secret" of amp tone - eq>dist and power attenuators
Home (amp tone and effects placement)

You can almost certainly get satisfactory sound from your existing decent tube amp,
without mods, by using, or at least experimenting with, the following  chain:
guitar
eq pedal
Comp/OD/Dist pedals
eq pedal
amp's preamp
amp's tone stack
amp's tube power amp
good power attenuator
amp's guitar speakers

The above is truly the "secret" of great amp tone.  Most postings, books,
and amp tone videos dwell on amp brands and mods and swapping tube types
and swapping speakers or pickups, but such priorities are backwards.
The real first order of business is knowing how to make the most of *any*
decent tube guitar amp.  It's a shame that most guitarists try all sorts
of things other than the secret weapon that gets straight to the point:
the eq>dist>eq pedal chain, which you can put before any guitar amp,
in conjunction with -- just as important at the other end of the chain --
some way of getting power-tube saturation independently of speaker volume,
and this amounts to the (unfortunately) "secret" of power attenuators.
-----------
End quote

My rig just takes this one step further and instead of attenuation I *reamplify* the tube power amp with another SState poweramp. Even without power tubes you can still make inroads to great tone.

This is the basic layout I use;
First a very simple DIY tone stack based on an old HiWatt circuit, SS
B> into a highly modified OD SS device
C> then a very simple tube amp which drives a resistive load
(like an attenuator cept No Speaker, you tap off a line level instead)
D> feed into an old HiFi graphic EQ
E> ultimatly driving a 120watt SS power Amp.

The tube amp is an old rewired Gramaphone from the 50's and only outputs 7watts,
no need for expensive tube gear here as you actually want a bad/cheap basic amp.
Heck it only has 1 volume and 1 tone knobs. All the rest can be done via SState.
Cheers, have fun, Phil.

Thanks for taking the time to compose this.  I feel stupid after reading it.