So i have just been dabbling around with my MP-1 and am just trying to figure out the best way to have my volume`s. I have heard that pushing the power amp to get tube distortion is favoured over pre amp tube distortion, so should i keep my master gains low, output level knob around 9 oclock or even 8 and then just crank up the power amp volume, or do i whack the volume to 1 or 0.7 and then just dime out the output level ?
Granted if i changed to another patch that did not have low gain i would probably jump out of my skin with the sudden jump in volume.I am currently running my MP1 through an ENGL 60 watt power amp
Is there a general rule of thumb on a certain level to run the MP-1? As it seems when i try out some tones i have patched in for the ADA it can get stupidly loud e.g
DT
od 1/17
gain 8
bass 2
mid 0
treb -2
pres 2
Hey Dna^Yay, have a read of the manual (http://adadepot.com/index.php?topic=111.0), there's a pretty good description on how to set up patches and set your OD levels etc.
ADA preamps are designed to be used with clean transparent power amps, all the tone and colour is done in the preamp.
(I have heard that pushing the power amp to get tube distortion is favoured over pre amp tube distortion), I think this kind of strategy comes from 60's 70's amp days where guitarist chased distortion from wherever they could get it, Blackmore used to kick a hole in his speakers to get some speaker distortion as well. While you can chase some poweramp distortion/colour if you want to, it's generally not how to run a MP1/2.
Typically, I run my power amp on 3/4 (give or take depending on venue/stage (maybe 1/2 for home/bedroom)), and control the overall volume with the MP1 output knob (set this with you loudest patch e.g. over the top killer lead solo). Set individual patch volumes with their master vol so you get the right volume change between patches (e.g. rhythm, lead). When creating patches, run them up at stage level first, then turn the output vol down for home/bedroom levels. MP1s are designed for stage use so they can get very loud if required >:D
Cheers Richard
DNA,
What kind of tone are you going for? Output tube overdrive is more of a vintage Blues type of sound, If you'll allow me to generalize. That's the tone I go for when I pick up my guitar, but I use amps similar to Fender blackface and tweed non-master volume amps. Sounds pretty clean compared to more modern amps with cascaded gain stages in their preamps.
Something in the back of my head never did sit right with that whole "poweramp distortion" thing, now I know why.
What about "speaker breakup"? Should one strive for that in these modern times (assuming you want nice cleans), or should one avoid it?
My gut says avoid it and go for a cleaner, articulate speaker tone like I get form my Carvin 2x12.
As for seting the mp-1, I typically set the volume according to the cleans, since it's easy to outrun them with the driven tones (from crunch to wail). Generaly I get too much compression for my tastes if the cleans are too loud in the Gains (SS voice), and I can't really get "good" clean tones with the Clean Tube voice.
As well, since the OD1 clip light comes on if I set it to anything above 4.5, I don't run it that high. OD2 can go to max for all I care, and I get plenty of distortion even for Thrash at about 7 on that.
Can't recall what my knobs are set to - not in front of it ATM. IIRC the Out is higher than the In.
I subscribe to the 'clean speaker' theory. I don't want my speakers breaking up at all.That's why I run a 50w amp into a speaker rated at 300w.
Nowadays though, I'm not bringing the amp or the speakers, just running directly into the mixer. Can't get any cleaner than that.
Oh, and I always start with the clean tones first too. That's the best attack plan
I usually run my power amp full tilt or thereabouts and use the preamps output volume set to whatever the room/situation calls for.
As for the speakers I always have some V30's in there. This rig I am putting together now will be in stereo with 2 4-12 Marshall cabs. One is GT1275's and the other vintage 30's. Should be rockin' :whoohoo!:
Thanks for all of the input guys!!
Just will have to mess around with it all.
Also would it be better to set my power amp at 4 or 8 or 16 ohms? Read somewhere that 4ohms is pretty loud, correct me if i am wrong. Currently am running at 8ohms
Quote from: Dna^Yay on March 18, 2014, 09:33:02 AM
Thanks for all of the input guys!!
Just will have to mess around with it all.
Also would it be better to set my power amp at 4 or 8 or 16 ohms? Read somewhere that 4ohms is pretty loud, correct me if i am wrong. Currently am running at 8ohms
Depends on the speaker impedance?
Quote from: Dna^Yay on March 18, 2014, 09:33:02 AM
Also would it be better to set my power amp at 4 or 8 or 16 ohms? Read somewhere that 4ohms is pretty loud, correct me if i am wrong. Currently am running at 8ohms
As MarshalJMP says - it depends on the speakers. Mismatching impedance is risky business, particularly with tube power amps.
Quote from: Dna^Yay on March 18, 2014, 09:33:02 AM
Thanks for all of the input guys!!
Just will have to mess around with it all.
Also would it be better to set my power amp at 4 or 8 or 16 ohms? Read somewhere that 4ohms is pretty loud, correct me if i am wrong. Currently am running at 8ohms
A tube power amp cranks out the same wattage regardless of impedance, the secondaries on your output transformer match the impedance of the output tubes to the impedance of the speakers. Running your poweramp at an incorrect impedance setting will most likely 'suck' tone due to the mismatch from output to speaker, but most importantly it could cause catastrophic failure in your poweramp. Won't get you any louder.
Some amps are more sensitive to impedance mismatches than others, just stick to the correct match.
Sorry, not trying to harsh your vibe, I just don't want to see you wreck your gear due to some bad advice. :homer:
Hey Dna^Yay, the stuff you read no doubt referrers to transistor power amps, they drive/deliver different output power (watts) depending on the speaker load, (in general more into less) as in a (tranny) power power amp may deliver 80 watt rms into 8 ohms and 100 into 4 ohms and less (~50 watts?) into 16 ohms (i.e. more resistance, less watts to the speakers), as BDS says, tube amps (as they have an output transformer) are different. Also with transistor amps, if you put to little a load on them (e.g. 2 ohm) than they are designed for, you can damage them (suck the guts out of them). Another side of the coin though is the speakers, 16 ohm speakers have more windings (more electrical resistance) but they are thus more efficient and sensitive. Its all a balance, but rule of thumb is match both the speaker impedance/resistance and power handling to what the power amp is capable of/designed for. (it's actually not quite that simple in that speakers change their resistance /impedance with frequency and other stuff)
Hey all
Thanks for the input,
So if i set my amp to either 4 or 8 ohms there is no real difference? Volume is louder etc? I would never mismatch the impedances as like some of you have said it would damage the poweramp and cab.
Are you talking about a tube or a solidstate amp?
Quote from: MarshallJMP on March 28, 2014, 04:08:53 AM
Are you talking about a tube or a solidstate amp?
DNA,
I'm assuming you're using a tube power amp ==>> Your 60W ENGL you referenced in the original post puts out 60W regargless of the impedance.
Yeah its a 60w stereo tube power amp, there is 2 sides so i guess it can be run in stereo. Also for each side my amp has the options to go 4 ohm 8 ohm or 16 ohm
I highly recommend you run your MP1 in stereo (use both amp channels) with either a stereo cab (some have a switch for this) or better 2 cabs, not only will you get more output (additional amp channel) it will sound great/better.
With all power amps (tube, SS) you should match the speaker box impedance with the amp (e.g. 4 ohms to 4 ohms, 8 ohms to 8 ohms etc). Tube amps have an output transformer which are generally fairly robust so an impedance mismatch probably wont hurt it too much unless you are driving it flat out for long periods (probably not that unusual with loud live guitar though) as this may cause the transformer to overheat. Audiofiles/hi fi buffs sometimes mismatch for other reasons (e.g. 4 ohm amp tap into 8 ohm cab gives better dampening (control of the "back wash" from a 15" speaker, pulls the cone up better)) but they aren't generally running the amp flat out.
With SS amps, the higher the cab impedance, the less power you get (e.g. 100w into 4 ohm, 75 watts into 8 ohms etc) but you will damage the amps output stage if you put to low a load (e.g. 2 ohm speaker load on amp rated to min 4 ohm load).
On your ENGL match the the amp to the speaker box impedance. If you cab is 8 ohms, use the amps 8 ohm tap. As the ENGL is stereo, it will have a separate output transformer for each channel with 3 taps (4, 8, 16 ohm) for each.
My main querie was is there any difference running 4ohm or 8ohm? I have the choice of both and wanted to know peoples experiences, does running a cab at a different ohm yield any benefits? The whole thing is very confusing
Quote from: Dna^Yay on April 13, 2014, 03:56:48 PM
My main querie was is there any difference running 4ohm or 8ohm? I have the choice of both and wanted to know peoples experiences, does running a cab at a different ohm yield any benefits? The whole thing is very confusing
Short answer without getting technical: No, there is no difference/benefit.
Quote from: BrokeDownSouth on April 13, 2014, 08:05:28 PM
Quote from: Dna^Yay on April 13, 2014, 03:56:48 PM
My main querie was is there any difference running 4ohm or 8ohm? I have the choice of both and wanted to know peoples experiences, does running a cab at a different ohm yield any benefits? The whole thing is very confusing
Short answer without getting technical: No, there is no difference/benefit.
+1 :thumb-up:
SS amps, lower impedance (typically 4 ohms minimum) more power output (benefit >:D )
Tube amps, see my previous post, benefit of miss match (i.e. "miss-match" not necessarily good/usually not good) can improve dampening factor (makes sense for deep bass (in some circumstances e.g. the lowest notes that a huge (pedals) organ goes down to as a higher dampening factor pulls up/stops the speaker cone better between notes), not for guitar so much, you "may ??" find the bottom end a little bit tighter).
Ok so figured out my cab can be run in stereo so 4ohms each side so once i get some new tubes for the dead side of my ENGL i will be able to run my ADA in stereo, does it really sound better in stereo even though its still coming from the same cab?
Also i am still messing with tones and just wondering if anyone would be able to try out a patch i have made and see if they have the same issue i have.
MP1 output Volume 11 o clock (5th dot)
OD 1 4.8
OD 2 5.5
Gain 8
Bass 4
Mid 6
Treble 6
Presence 6
No chorus
My power amp volume is set rather low but i am sure you can accommodate it for whatever amp you all use.
......................
Now do you get a horrible squealing whistling sound? As if a kettle is miked up and whistling at you?!?
I will be purchasing an ISP Decimator soon and hope this will rectify this, but its just freaking annoying!!
The horrible squealing whistling sound could from a bad wired guitar or the cable between the guitar and the mp-1,or do you put something else in that signal pad?
Have tried it with various guitars and leads and it's still there. Could it be the tubes are old and broken? Haven't changed them since I got the mp1 in 2008.
Quote from: Dna^Yay on May 01, 2014, 07:56:03 AM
Ok so figured out my cab can be run in stereo so 4ohms each side so once i get some new tubes for the dead side of my ENGL i will be able to run my ADA in stereo, does it really sound better in stereo even though its still coming from the same cab?
If you put both STEREO OUTS into the same cab it won't sound any better (unless it is a speaker cabinet wired for stereo) b/c you're still just getting MONO. Also, your risking damaging your power amp running both sides into one cab (needs to be put into BRIDGE MONO mode to do this). Hook up each side of the power amp to a separate cab and then you'll be able to hear the stereo.
[/quote]
If you put both STEREO OUTS into the same cab it won't sound any better (unless it is a speaker cabinet wired for stereo) b/c you're still just getting MONO. Also, your risking damaging your power amp running both sides into one cab (needs to be put into BRIDGE MONO mode to do this). Hook up each side of the power amp to a separate cab and then you'll be able to hear the stereo.
[/quote]
I think the cab is wired for stereo, it has 2 inputs, one which is 8ohm and 4 ohm and the other is 4ohm, there is also a switch which you can change from mono to stereo and can take up to 150 load.
Ages when i got my amp i roughly recall putting it into the wrong input i think and remember sound only coming out of 2 speakers out of one side of the amp
Quote from: Dna^Yay on March 28, 2014, 03:15:12 AM
Hey all
Thanks for the input, So if i set my amp to either 4 or 8 ohms there is no real difference? Volume is louder etc? I would never mismatch the impedance's as like some of you have said it would damage the poweramp and cab.
The ENGL is a tube amp yes? So you get quiet different results to a SS amp when speaker impedance changes. It's always best to match amp/speaker impedance settings, there are scenarios where you can get different results (but as previous posts, with tube amps you can get different dampening factors (~how tight the speaker cone pulls up, particularly with bottom end)) by miss matching. If you don't understand it don't do it. When you use a stereo cab the sound in the box interacts in a different way to having 2 separate cabs (spread as wide as you can... >:D ) you can get lots of "in box" phase cancellations, so 2 cabs is better than one stereo, but 1 stereo is better (with MP1/2) than 1 mono, and stereo MP1/2 is sooo good, if your like me you'll never go mono again....
Seems your box is 8 ohm mono, or 4ohm left, 4 ohm right ((i.e. 4 x 8 ohm speakers) set ENGL accordingly, i.e. 4ohm (left/right) and run in stereo, switch cab to stereo ???, or mono use 8 ohm ENGL and 1 speaker lead/channel). It will sound soo much better in stereo, try it...
Quote from: rnolan on May 02, 2014, 07:55:21 AM
The ENGL is a tube amp yes? So you get quiet different results to a SS amp when speaker impedance changes. It's always best to match amp/speaker impedance settings, there are scenarios where you can get different results (but as previous posts, with tube amps you can get different dampening factors (~how tight the speaker cone pulls up, particularly with bottom end)) by miss matching. If you don't understand it don't do it. When you use a stereo cab the sound in the box interacts in a different way to having 2 separate cabs (spread as wide as you can... >:D ) you can get lots of "in box" phase cancellations, so 2 cabs is better than one stereo, but 1 stereo is better (with MP1/2) than 1 mono, and stereo MP1/2 is sooo good, if your like me you'll never go mono again....
Seems your box is 8 ohm mono, or 4ohm left, 4 ohm right ((i.e. 4 x 8 ohm speakers) set ENGL accordingly, i.e. 4ohm (left/right) and run in stereo, switch cab to stereo ???, or mono use 8 ohm ENGL and 1 speaker lead/channel). It will sound soo much better in stereo, try it...
+1 good answer. DNA, post a picture of the back of your cab with all the jacks and stuff.
Hey Guys
Sorry for the reallllly late reply, had to send my MP1 off to MJMP to get it fixed!
So today wired it back up again and here are the pictures of the back of my ENGL and Randall cab
So for stereo use set the cab switch to stereo and then 2 cables to the power amp left and right 4 ohm inputs.
So everything okay now with the MP-1??
Quote from: MarshallJMP on August 26, 2014, 01:49:16 PM
So for stereo use set the cab switch to stereo and then 2 cables to the power amp left and right 4 ohm inputs.
MJMP means connect 2 speaker cables, one to each of the ENGL 4 ohm outputs and plug the other end into the cabs 4 ohm input jacks, and switch cab to stereo. Don't turn the power on until it's patched/switched properly.
A word of warning (as another member accidentally gave his power amp output stage a permanent suntan not so long ago), heed the warning on the back of the cab and DONT switch it (cab) to mono when plugged into stereo power amp.
The ENGL is interesting, there are quite a lot of patching options, even a stereo effects loop (probably a good spot for a BBE or a noise gate, but probably for eq). I'm not sure about a couple of the options, do you have a manual ? Normally you'd plug your MP1 outs (A/B) into the ENGL A and B inputs, then there's the stereo switch (probably parallels the A and B inputs for mono so you can just plug into one input), but set this to stereo. The the A/B <> A/B::A/B <> Volume switch I'm not sure what this does. :crazy:
That was my original plan but one of the power amp tubes has died on the left hand side so only the right works.
When i was running one output from the ada into the right side it was sounding good, but then when i put both A and B outputs into the A and B inputs of the Right side, the volume difference was huge!! I guess with the Engl say i was running a mono preamp i could have say the ADA into the A and another amp to the B input and there is a switch at the front which changes between A and B, obviously in my case though this does not change anything as both inputs have the ADA in.
I have included the ENGLs manual so everyone can have a look at it!
Possibly thinking as both ADA outputs are into the AB right inputs, maybe put another speaker cable out of the right side 4ohms and change the existing 8ohm to 4ohm then run my amp in stereo?
Finally messed around with it yesterday for the first time, had a good chance to go through everything, was going to drop you a message. It sounds really good!!! That squealing is still there but i think thats something with eq because when i set the ada eq flat and used an mxr 10 band through the effects loop, boosting some frequencies did producing some constant squeals even if i was on the clean channel, i will just have to figure a way around it.
There was an issue with OD 1 occasionally popping when going from 2.2-2.4, some hissing at 3.4 then popping and going silent to 3.6 then a pop at 6-6.5 then after that i barely could hear a difference between 6-10 when adjusting up or down.
I was working through the Nuno and Paul Gilbert ADA patches and was trying to figure out the best set up as with Nuno`s patches he has the output volume around 1-2 o'clock and most of his master gains for clean and distorted are at 3.5 max. While some of PGs tones vary and at 1-2o clock output volume is very loud for some of his patches. So i am trying to figure out what is the best method, run the output volume pretty high 1-3 o'clock, then adjust all of my patches so their master gains never really go past 3-4 and then push the volume out on my ENGL, or run the ADA output volume around 10-12 and then crank the master gain of the patches up to 6-8?
Thanks for the manual, I get it now. One of the main features it offers is to be able to run 2 stereo preamps into it (gives each their own vol and pres settings) and then select between them via midi/footswitch. So to use with your MP1, you want it to be as simple as possible (just a stereo power amp). First it sounds like it needs a new set of tubes :thumb-up: (listed in the manual, basically some 12AX7s (Input/buffer) and some 6L6s or 6550As (power tubes)). So power tubes - (these look good (http://www.dougstubes.com/tung-sol-6550.html) if you've got a 930/120) or if it's a 930/60 (http://www.dougstubes.com/power-tubes/mullard-6l6gc.html);
Input/Buffer tubes these are my pick (http://www.dougstubes.com/preamp-tubes/mullard-cv4004-12ax7.html)
Amp set up - So to keep it simple, (when both channels are working again), MP1 A out > ENGL A input right, MP1 B out > ENGL A input left, select A input(s) on front (3), then Left A and Right A vol knobs control the volume (set them to 3/4 (2 to 3 o'clock)) and adjust MP1 output knob to suit. You can play with the other switches (e.g. (bass) depth boost) but I'd keep it flat, it would probably sound good at low vol though (bedroom). I have presence knobs on my Carvin TS100, never use them I create the tones in my MP2, but if you want to add some 6khz, you can crank them up (will help MP1 stand out in a mix but each patch has it's own presence setting...).
The input gain should be set to accommodate MP1 output range, I'd go gain lo (- 5 dB, max. 15 dB) (gain hi will boost the signal (-23 dB, max. -3 dB)).
No Problem!
I was talking to Eddy at Eurotubes a while back and i spent ages contacting ENGL about seeing what tubes i could put in them, KT88s etc. Safe to say though after months of no emails then eventually some, i think i will get some new 6L6GCs in one side and 6550s in the other (or it might be 5881, cannot remember off the top of my head what the guy said).
Was looking into getting some Genelex gold lions, obviously want to buy all my ENGL and ADA tubes at once so everything is fully matched. Once i get some dollar i will go out and get some tubes, currently running the stock gain mod so only a 2 tube ADA.
At the moment with just one side of the ENGL working, is it possible then to have both AB ADA outputs going into the AB of the Right Side of my ENGL, like it currently is in the picture, then just swap the 8ohm into the 4 ohm and get another speaker cable into the other 4 ohm so its ...
MP1 A and B Out > ENGL A and B Right Side > both 4 ohm Parallel Right into Randall cab switch set to Stereo 4ohm?
Yeah i currently have the gain input button set to low otherwise it is just far too loud. With regards to the volume setup you suggested, like i said in my last post, do i do a Nuno and crank the ADA output volume to around 1-2 oclock, set the ADA gain to about 3-4 for dirts 4-5 for cleans, Or have the ADA output volume around 10-12 oclock and the gains pushed around 6-7.5? Then after that would you say its better to hang the ENGL volume cranked to 2-3 oclock and lower the ADA volume, or have the ADA volume cranked and control the ENGL volume?
(MP1 A and B Out > ENGL A and B Right Side > both 4 ohm Parallel Right into Randall cab switch set to Stereo 4ohm?)
No and be careful :facepalm: The ENGL speaker outs on each channel are in parallel (check manual TIP 7). So if you connect 2 separate 4 ohm speaker loads (by setting Randall cab to stereo and 2 speaker leads), the ENGL Right channel will see 2 ohms (jacks are in parallel so 4 + 4 = 2). Better to use one speaker cable from ENGL Right 8 ohm jack and RCab on mono 8ohms.
Also MP1 A/B into ENGL Right A/B means if you select ENGL A you get MP1 A, selecting ENGL B selects MP1 B into the ENGL Right channel, The ENGL A is for A of one preamp, and B is for A of a separate preamp (it's just for switching versatility between 2 preamps e.g MP1 and Soldarno etc so you plug MP1 A/B into ENGL Right A and Left A, Soldarno A/B into ENGL Right B and Left B then you can switch between the 2 preamps by selecting ENGL A or ENGL B button). The ENGL has a Right and Left channel, each channel has 2 inputs A and B which you can switch (i.e. pick L/Rs A signal, ot L/Rs B signal)
Better to go MP1 A out to ENGL Right A, MP1 B out to ENGL Left A (now your in stereo :thumb-up: note select A (preamp) on ENGL), Randall cab set to stereo, ENGL Right 4 ohm Speaker out to Randall Right, ENGL Left 4 ohm Speaker out to Randall Left.
I don't think you can use different output tubes for left and right channels, (as you can with Carvin TS100) (check manual) It says for 930/60 use 6L6GC Matched (per side), or if you have 930/120 use 6550A Matched per side.
Go with matched 6L6s if you have a 930/60 OR 6550As only if you have a 930/120. For all the 12AX7s (3) I'd use Mullard reissues, nice tubes BTW.
Quote from: rnolan on September 04, 2014, 06:42:04 AM
(MP1 A and B Out > ENGL A and B Right Side > both 4 ohm Parallel Right into Randall cab switch set to Stereo 4ohm?)
No and be careful :facepalm: The ENGL speaker outs on each channel are in parallel (check manual TIP 7). So if you connect 2 separate 4 ohm speaker loads (by setting Randall cab to stereo and 2 speaker leads), the ENGL Right channel will see 2 ohms (jacks are in parallel so 4 + 4 = 2). Better to use one speaker cable from ENGL Right 8 ohm jack and RCab on mono 8ohms.
Also MP1 A/B into ENGL Right A/B means if you select ENGL A you get MP1 A, selecting ENGL B selects MP1 B into the ENGL Right channel, The ENGL A is for A of one preamp, and B is for A of a separate preamp (it's just for switching versatility between 2 preamps e.g MP1 and Soldarno etc so you plug MP1 A/B into ENGL Right A and Left A, Soldarno A/B into ENGL Right B and Left B then you can switch between the 2 preamps by selecting ENGL A or ENGL B button). The ENGL has a Right and Left channel, each channel has 2 inputs A and B which you can switch (i.e. pick L/Rs A signal, ot L/Rs B signal)
Better to go MP1 A out to ENGL Right A, MP1 B out to ENGL Left A (now your in stereo :thumb-up: note select A (preamp) on ENGL), Randall cab set to stereo, ENGL Right 4 ohm Speaker out to Randall Right, ENGL Left 4 ohm Speaker out to Randall Left.
I don't think you can use different output tubes for left and right channels, (as you can with Carvin TS100) (check manual) It says for 930/60 use 6L6GC Matched (per side), or if you have 930/120 use 6550A Matched per side.
Go with matched 6L6s if you have a 930/60 OR 6550As only if you have a 930/120. For all the 12AX7s (3) I'd use Mullard reissues, nice tubes BTW.
Ok i understand now, i had a proper think about everything and analysed my amp good and proper. So if the 4ohms are in parallel and both connected it equates to 2 ohms? 8+8=4ohm , and there is only one output either side for the 16 ohm.
So if i only wanted to use the right side of the ENGL but use 2 cabs i would use both of either the 4 or 8 ohms? or could i have one 4ohm cab and one 8 ohm cab coming out of the right side? Amps and their ohmage have always confused me hence why i have never dabbled with stereo or extra cabs.
Then i guess when plugging the ADA into both left and right ENGL input A it will then be running in stereo, i have the option to have another stereo preamp going into either side of the ENGL B and then i just use the input A/B switch to swap between stereo MP1 or stereo (insert stereo amp name)?
With the power amp tubes, i was told really my options were the 6L6GCs, 5881s, KT66 which are all the same group of tubes, so i thought as long as i bought all 4 together matched and then have them biased then i will have different tonal qualities coming out of either side of the amp?
Have been looking at your choice of Mullard power and pre amp tubes, was also browsing into the Genelex gold lion brand of power and pre tubes but was unsure. Having a look on the forum to see what other peoples experiences are of tubes they have used as i would need to get 2 for the MP1 and 3 for the ENGL.
Ok, your getting there but still haven't quite grasped the ENGL. Part of the problem is labels (left right, a/b etc). So lets break it right down to fundamentals. The ENGL is a stereo power amp, it has a left (mono) channel and a right (mono) channel = L/R stereo. Each separate channel (i.e. L/R) has 2 inputs A & B which you can switch between, so Right A and Left A = stereo L/R "A" and Right B and Left B = stereo L/R "B" So you have preamp 1 (e.g. ADA MP1) A out > ENGL Right A in and B out to ENGL Left A in (so selecting A on the ENGL picks MP1 in stereo). Then you can go Peamp2 (enter preamp name (e.g. MP2 >:D ) A out > ENGL Right B and B out > ENGL Left B (so selecting B on the ENGL picks the MP2 or whatever). So this is used to select between 2 "stereo" preamps (A L/R, or B L/R). If you just have one preamp (MP1), connect MP1 A out to ENGL Right A and MP1 B out to ENGL Left A. Now each side of the ENGL (L/R) has input signal (select A on ENGL front BTW as you want the L/R "A" inputs).
Now you have the speaker outs, they are a little confusing albeit very versatile. Each channel (L/R) has 3 connectors, 16 ohm, 8 ohm, 4 ohm. For your setup, connect the 4 ohm from ENGL Right to cab R and 4 ohm from ENGL Left to cab L.
Don't get confused with the labels, if you just use the right channel of the ENGL, it's mono and the left channel is doing nothing, selecting the A input or B input on the front just picks between the 2 input sockets for that channel.
So you need to get signal into ENGL Right channel and Left Channel and run half your cab from ENGL Right out and the other half from ENGL Left out