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[rnolan]

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.

[Dna^Yay]

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

[BrokeDownSouth]

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.

[rnolan]

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 

SS amps, lower impedance (typically 4 ohms minimum) more power output (benefit  )
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).

[Dna^Yay]

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!!

[MarshallJMP]

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?

[Dna^Yay]

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.

[BrokeDownSouth]

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.

[Dna^Yay]

[/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

[rnolan]

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... ) 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...

[BrokeDownSouth]

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... ) 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.

[Dna^Yay]

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

[MarshallJMP]

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??

[rnolan]

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.

[Dna^Yay]

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?