ADA Depot - A Forum To Support Users of ADA Amplification Gear
Let's Get Technical => Schematics & Modifications (mods) => Topic started by: trader144 on October 31, 2014, 12:19:08 PM
-
Just wondering.
I know the mdrt is the upgraded transformer of choice, but it is expensive.
Is there an upgraded transformer mod that takes the transformer out of the rack, similar to a wall wart, so that there are options other than the mdrt?
David
-
Hey David, there a post on here somewhere that discusses what you are suggesting, the consensus was it's doable although I suspect it would need to be a custom job ? to have the right taps for the tubes.
I'm the opposite, I'd like to get rid of the wall warts in my rack (quadverb, midiverb) as they are a hassle and get loose etc particularly the quadverb, the transformer is half way along and it's big and it's come off it's Velcro.....
I don't know of any other transformer mods apart from the original replacement (on MJMPs site) and the MDRT, not to say someone else may have tinkered with this ?
As I understand it, the MDRTs are a custom run/make so very low volume which will make them more expensive
-
True but the thought is I can get the transformer farther away from the board, and, maybe I can use standard production parts instead of a custom run.
I don't like wall warts either but given heat, buzz, and custom wind they are looking pretty good.
-
You will never find a wall wart with the voltages the mp-1 needs,you need 2 x 13Vac,2 x 18Vac and 1 x 240Vac.So you need something that's custom made again.Also an MDRT weights around 800 grams,that's a heavy wal wart.
-
Ok got it
-
Feast thine eyes on the M......D......R.......Teeeeeeee
time to join the club
"Speaking generally, higher voltage stages are cleaner, punchier, and have more headroom (ability swing more signal before the point of clipping), while lower voltage stages tend to be flatter in response, smoother, and distort earlier."---Joey Voltage
this could be just what I have been looking for to get better sound out of my mp-1 at lower OD1 and OD2 settings.
found a guy who hadn't installed his kit and bought it from him
-
Hey David, cool :thumb-up: :whoohoo!:
-
Wow that's an early version of the MDRT
-
Is that good or bad?
-
The transformers are all the same,it's just the way they are build.So no worries ;D
-
As everyone knows the MDRT transformer puts higher voltage to the tubes.
It think it basically doubles the voltage and the 300k resistor increases the voltage to the heater to
240 volts.
Has anyone experimented with higher voltage?
I think this might be the limit for the 12ax7.
David
-
The heater voltge is 12.6V vs 9V from the original tranny,HT is 240V vs 190V for the tubes.(if you change R9 with a 300k resistor).
The limit according to the datasheet is 300V.(plate voltage)
-
Just installed the MDRT. Impressive custom piece of equipment and MJMP's instructions could not be easier.
Great improvement in sound and really brings the guitar out close and in 3D.
As expected the lower gain stages are much more useful now and there is more punch.
Had to dial back the master by 1.0 on clean tube and 0.5 on tube distortion as the additional power increased the clipping but that is not a problem.
A few questions please:
Why limit the voltage to 240 instead to 300v ? Is that the max for the transformer ?
Why do I only need to change the tube board resistor when the voltage increased and there are other components?
Why increase the capacitor from 4700uf to 10000uf? I know this allows for more charge to be stored but is it basically just 2x due to the new transformer?
The original transformer looks very weak and cheap compared to this work of art.
Great stuff MJMP thank you.
-
Ultimate thanks go to Machinator, (Machinator Designed Replacement Transformer (MDRT)), but many thanks to MJMP :bow: for keeping them coming :thumb-up:
-
Why limit the voltage to 240 instead to 300v ? Is that the max for the transformer ?
==>i could go a bit higher but the caps on the tubeboard are only rated for 250V,so i need to stay below that voltage.
Why do I only need to change the tube board resistor when the voltage increased and there are other components?
==>if you don't replace it the voltage will stay at 190V even with the MDRT.The tubeboard has a voltage regulator onboard.
Why increase the capacitor from 4700uf to 10000uf? I know this allows for more charge to be stored but is it basically just 2x due to the new transformer?
==>this way you will have less ripple on the 12.6V rail for the tube heaters which results in less hum.
-
Thank you
-
Marshall... the man with a million answers! jeje
-
Marshall... the man with a million answers! jeje
+1 :thumb-up:
-
Mmm only have 999.998 answers left :lol:
-
Hey El, you should have said a gazillion answers LOL. Interesting idea though, how many questions/answers do we do in our life ? A shitload comes to mind :lol: And to what extent do they affect our happiness and longevity (allot I suspect).
-
So from what I have read the increased plate voltage from the MDRT gives you more headroom (less distortion) because it creates a wider operating range within the tube and therefore becomes harder to clip the input signal at the signal peaks. Ignoring the corresponding increase in grid voltage of course.
The downside is less gain and you loose the brown sound.
I have a 60's Nos mullard in V1 and a GT Mullard spec in V2 and it sounds really good.
Still have more gain than I need but the headroom increase and clarity is really nice and the ability to cut through the band is much better.
-
Hey David, not sure how that equates to less gain ? Gain and clipping are different things. More headroom = more gain before ultimate clip of circuit, and as you say more room for bigger transient peaks.
Nice Tubes BTW :thumb-up: . When more MDRTs turn up, MikeB is going to put one in his MP1, looking forward to hearing the difference.
Hey MJMP, any news on the MDRT availability front ?
Cheers R
-
Rnolan is right,more voltage will give a bit more gain,not alot but still.
Like i said in the other topic,not yet. :facepalm: Sorry.
-
I meant to say less distortion, not less gain--my error.
-
Hey no worries, gain and distortion are kind of used a bit interchangeably here as we discuss clipping the tubes (eg high gain tubes = more distortion/clipping >:D ). Also when I talk about gain structure (which I rabbit on about (Rabbit Richard of the Down Under LOL)) I'm talking about end to end gain of set up, not just the preamp Tube gain (although it's the centre of attention), kind of an audio engineer view.
Hey MJMP, thanks for trying so hard for us all :thumb-up:
-
Yeah I want and MDRT n all!!!
Random question:
If one installs an MDRT, it can run on both US Voltage 120v and European Voltage 240v? So depending on where you are does this affect the sound then?
-
Hey RG, shouldn't affect the sound, it's designed (as I understand it) to work on both normal voltages and US voltages LOL, and has an earth :whoohoo!:
-
didn't trader144 say something earlier about why 240volts over 300v? And this was in relation to the sound? This is why I asked my question because it was mentioned earlier how the voltage affects the sound.
Why limit the voltage to 240 instead to 300v ? Is that the max for the transformer ?
==>i could go a bit higher but the caps on the tubeboard are only rated for 250V,so i need to stay below that voltage.
Why do I only need to change the tube board resistor when the voltage increased and there are other components?
==>if you don't replace it the voltage will stay at 190V even with the MDRT.The tubeboard has a voltage regulator onboard.
Why increase the capacitor from 4700uf to 10000uf? I know this allows for more charge to be stored but is it basically just 2x due to the new transformer?
==>this way you will have less ripple on the 12.6V rail for the tube heaters which results in less hum.
-
didn't trader144 say something earlier about why 240volts over 300v? And this was in relation to the sound? This is why I asked my question because it was mentioned earlier how the voltage affects the sound.
My question was about the voltage to the tubes and if there was more room to raise it, not the wall voltage.
MJMP's MDRT installation instructions say to make sure you have the right MDRT for your voltage (US/European) but they can be exchanged with some modification.
More voltage to the tube affects the sound as we all have read. Increasing the tube plate voltage to 240v basically makes the top and bottom amplification tunnel wider and more spread apart so the sound is more articulate and 3D and louder-more gain. If we did this alone and did not change the grid voltage, it would produce less distortion than the original transformer because it is harder for the guitar signal to reach the tube clipping point of the wider amplification tunnel.
But....The tube distortion also depends on the voltage of the grid relative to the anode voltage. This grid voltage is the guitar signal running into the tube that will be amplified by the tube inside the tube amplification channel. A wider input signal is going to hit the tube clipping limits of the amplification channel faster and as a result will create more distortion. Prior to the MDRT the typical way to adjust the guitar signal width (i.e. What the tube will be amplifying) was via trimpot and/or changing a resistor.
In addition to increasing the plate voltage to 240v, the MDRT basically doubles the grid voltage which allows a wider guitar signal to flow into the tube for amplification. Alone this would produce more distortion as it will hit the tube clipping limits faster.
But you have to look at both. While the plate voltage is increased from 190 to 240, or about 26% and the tube amplification channel is wider, the grid voltage is doubled. So the result of the MDRT is more clean headroom, more 3D and more gain and more distortion...but not more of the same type of distortion because the specs are all different and the tubes clip differently.
The downside? At lower plate voltages the tube will clip faster and create more of a brown sound than at higher voltages.
I think I am hearing a different type of distortion at top end levels than when I had the original transformer. It is less digital-like saturation and more of a real overdriven tube.
David
-
I see, so the wall voltage is not the voltage of which you were referring.
I guess I thought the MDRT was like one of those transformers that could handle both us and European voltage but without any tinkering like in other effects units that can take 120v or 240v.
I think I may not get one now after all, I'll have to think about it.
Is there any noticeable difference in replacing an older transformer with a new transformer sound wise?
-
I though the MDRT was for both voltages ? David, isn't yours an early version IIRC MJMP said is different construction to new ones (though don't know if this includes AC in).
(Is there any noticeable difference in replacing an older transformer with a new transformer sound wise?) Mmm never been there, MJMP ? I suspect early transformers are better as the materials were better, that's how it tends to go for tube HiFi audio, the fantics like the oldest transformers, they say they are built better from better bits...
Though IIRC MJMP said the MP1 original transformer is not a good design (hence Machinator designed a new one).
-
The MDRT is designed to work on 110V or 220V but you need to do some rewiring.
Yes the MDRT will sound better due to the increased voltages and currents.
-
Hey MJMP, can the rewiring be made a switch ?
-
Yes there are special switches that you can use to switch from 110 to 220V.But unless your alot on tour in different country's i don't see why you would need it?
-
Hey thanks MJMP, I think RGerry may need it ?? (why I asked BTW), he seems to be doing a bit of FIFO.
-
Is there any noticeable difference in replacing an older transformer with a new transformer sound wise?
There is company in the US (I think it begins with an M) that claims to make replacement transformers can't remember the name and I haven't read about it other on one other forum so probably not many reviews.
MJMP said somewhere on here thy he bought one to try it but wasn't impressed. They also have a 240v version that is hard to find and you would need to check if that means 240 to the tube or just European voltage.
The space for the transformer in the MP-1 is a tight fit so I would get reviews first and maybe a guarantee if fit.
Update: the company is mercury magnetics but I have no idea of their quality or existence.
David
-
The Mercury is just a copy of the original tranny and is quite expensive,costs even more then a MDRT.
-
Hey thanks MJMP, I think RGerry may need it ?? (why I asked BTW), he seems to be doing a bit of FIFO.
Yes Richard I probably will in the future if I'm honest. Not this year may be.
To be a little more specific I thought the MDRT was like a transformer that detected the voltage coming in and switched itself. Manual switch would still be a good option I guess. I was mainly asking about this switching to and from for curiosity, just because I assumed it was automatic like others I have used.
Currently the MP1 i got is Yankey at 110-120. I use a Mercury transformer to step down my power outlet from 240 to the required. That Mercury transformer was cheap as piss and it does the job splendidly.
The 3TM i will be getting soon, is UK 240. I wonder has that guy changed the transformer in it? Must ask him.
-
You'll be surprised..... The 3TM Ultra+ comes with the MDRT and all bells and whistles :thumb-up:
-
actually yeah it is an ultra!!! So it will have a MDRT!!
Well I'll know pretty soon what it will sound like then wont I :)
-
I've played a little with step downs, not a fan IMHO, seems hums come in etc..
-
not detected any hum of this one Richard, other than the actual transformer makes a noise, as does the MP1. Nothing audible. I have not played that MP1 through my live rig yet. I will let ya know.
-
Is it the ultra or the ultra+?only the "+" has the MDRT!
A word on "detecting the voltage".Transformers can't detect incoming voltages.I guess you are talking about switching power supplies,these can run on different voltages but are loaded with electronics which are more prone for breakdown.I rather have a good old fashioned transformer,much more sturdy!
-
Is it the ultra or the ultra+?only the "+" has the MDRT!
A word on "detecting the voltage".Transformers can't detect incoming voltages.I guess you are talking about switching power supplies,these can run on different voltages but are loaded with electronics which are more prone for breakdown.I rather have a good old fashioned transformer,much more sturdy!
I don't know the tecnhincal terms, but yeah that's what I mean, power supply that can run on both. That is what I thought the MDRT was just because I know it can do both. I didn't realise it needed to be switched one way or the other.
And yeah it's an 3TM Ultra Plus, the guy showed me the receipt from you.
-
Was the MDRT installation designed with a specific MP-1 tube compliment in mind?
Reason I ask is that all we change is a filter capacitor and the resistor that establishes the cathode ground reference voltage.
Since we do not adjust the cathode or plate resistors it seems like it was designed to bias a certain tube (e.g. Bias)....Thoughts?
Is the purpose of that C131 capacitor to filter out signals above 10000uf? It appears to be a filter rather than a coupling capacitor. Why did we use 10000uf for the MDRT vs 4700uf for noise mod V2 without the MDRT and what I think is 11300uf from the original schematic?
Thank you
David
-
Ok, so my take on the discussion is the MDRT can run of different mains but requires a switch set up so you can select the right taps on the transformer and they are solid old school kick ass transformers, not like the new switching transformers (and I side with MJMP here, the older rock solid are the go).
So MJMP, what would the switch and associated circuit look like to switch from 110 to 240 ?
-
Well the MDRT has 2 110V windings,so for 110V use put them in parallel,for 220V put them in series.
-
Was the MDRT installation designed with a specific MP-1 tube compliment in mind?
Reason I ask is that all we change is a filter capacitor and the resistor that establishes the cathode ground reference voltage.
Since we do not adjust the cathode or plate resistors it seems like it was designed to bias a certain tube (e.g. Bias)....Thoughts?
Is the purpose of that C131 capacitor to filter out signals above 10000uf? It appears to be a filter rather than a coupling capacitor. Why did we use 10000uf for the MDRT vs 4700uf for noise mod V2 without the MDRT and what I think is 11300uf from the original schematic?
Thank you
David
No it wasen't,Machiniator designed it to give the MP-1 the transformer it needed,with the correct voltages and more then enough current.
The 10.000µF filters the hum going to the heaters.The original tranny has sometimes startup problems with a 10.000µF but the original 3300µF can be replaced with a 4700µF if you have the orignal transformer.Did some testing and this as high you can go,the MDRT has no problem at all with the 10.000µF.
-
Ok thanks
-
Well the MDRT has 2 110V windings,so for 110V use put them in parallel,for 220V put them in series.
Ok so fairly simple switch ? (bit like PU series parallel switch but beefier >:D )
-
Just fitted the MDRT to my 230v unit and it is well worth it
I know it's relatively expensive but it really brings the MP1 to life.