More discoveries with the Mansfield bias mod.

[alie123]

Hello !
As promised: Yesterday my ACE sounds very good. I think, he never sounded this good. !!!!!!!!!!Also at LOUD volumes.!!!!!!!!!!!!! YESSSS..

Still it's a bright tone, but not harsh anymore! Even if I keep treble & Prescence low. But I don't care if have to keep my treble and prescence LOW, or sometimes almost OFF, .. the thing that matters to me that is that I heard a good tone from my amp.! I can turn up the treble to about 10 or 11 o clock if I want, but then I have to bring the MID way down because dailing in MID brings also a lot of treble in the sound of the ACE.. (I prefer keeping treble & Prescence LOW and bring in MID as much as possible without getting ear-pearsing sounds..) I used the FAT clean mode, and channel2 crunch and tite gain mode.

This were results of the first time. I hope I will still like my ´reborn´ amp the next time. Monday I play with another band in another room. I´m already looking forward testing my amp again.

Other interesting point: I have a BB preamp. I didn't use it much because I think it sounded bad through my ace. (harsh) Yesterday it was great! I think I'm happy with my ACE for the first time . !!

cheers!

 

[inkwachemis]

Hello !
As promised: Yesterday my ACE sounds very good. I think, he never sounded this good. !!!!!!!!!!Also at LOUD volumes.!!!!!!!!!!!!! YESSSS..

Still it's a bright tone, but not harsh anymore! Even if I keep treble & Prescence low. But I don't care if have to keep my treble and prescence LOW, or sometimes almost OFF, .. the thing that matters to me that is that I heard a good tone from my amp.! I can turn up the treble to about 10 or 11 o clock if I want, but then I have to bring the MID way down because dailing in MID brings also a lot of treble in the sound of the ACE.. (I prefer keeping treble & Prescence LOW and bring in MID as much as possible without getting ear-pearsing sounds..) I used the FAT clean mode, and channel2 crunch and tite gain mode.

This were results of the first time. I hope I will still like my ´reborn´ amp the next time. Monday I play with another band in another room. I´m already looking forward testing my amp again.

Other interesting point: I have a BB preamp. I didn't use it much because I think it sounded bad through my ace. (harsh) Yesterday it was great! I think I'm happy with my ACE for the first time . !!

cheers!

great info alie. about the clean channel: when u are running it in the high bias setting, have u noticed it overheating too much or anything? how does the fat clean sound now? and is there less headroom? thanks man!

 

[alie123]

Have just heard my amp once at band 'volumes' because yesterday practising with the band was cancelled.. :-(
What I've noticed.. no problems with overheating, and no problems with less headroom or something. In fact, I like it better than before the mod, ..in both tube/diode settings. I played mostly the tube setting. Plus, the BB preamp (or other pedals) on top of channel1 sounds also better to my ears.. I forgot to play the tite clean setting. Next time I will do. I like the quick/tighter mode for some rhythem sounds.

 

[garbagetruckdriver]

Hey guys,

A couple days ago I did Isaac's (berumen77) suggested preamp mods to my Stiletto Deuce (stage 1). It certainly went some of the way to remove the fizz from Ch 2.

Today I installed the Mansfield Bias mod. Interestingly, I found the plate current hovering down around 20mA for Ch 2 with Diodes (baseplate V was almost 480v). So I cranked that up to 35mA for Ch 2 which gave around 30mA when switched to Ch 1. I could go further but I figured let's try this for now.

Now my power tubes emit that lovely warm smell like my old Mark III Simulclass combos used to have. I miss that (they don't appear to be red plating)

The change to the sound is exactly what I expected given the previous comments here. Rather than spew superlatives, I'm just gonna say - do it!

I did have to run out and buy a good old fashioned analog multimeter though - my lovely, but somewhat vintage, Fluke 73 digital meter just didn't have the speed or scale to tell me what I needed to know.

Cheers
Sean
I'm gonna shut up and go play now coz it's time to channel me some Angus Young...

 

[alie123]

hi garbagetruckdriver,

Great to hear you also did the bias mod, and liked it. You've also did Isaac's mods.
Before I've installed the bias mod, I did Isaac's mods, but when I installed the bias mod, I did undo Isaac's mods. (to start from the original starting point) Isaac's mods are great, and I really appreciate his great discoveries, but after the bias mod I think I don't need to redo the mods again, because I like the amp it sounds at this moment.

I am still very curious what preamp mod's you did to your amp. The mod I liked most was replacing the 39k to the 33k slope resistor.. Mayby some day I will redo the mod again

bye!

 

[garbagetruckdriver]

alie123,
I did the input jack shunt resistor and the cap across the treble pot. The one he most recommended was the presence resistor mod #4 - but interestingly on my Stiletto Deuce stage 1, I already had a 4.7Mohm resistor, not the 10Mohm he started with - I recall his original post was not for a Stiletto Deuce though. The 4.7M resistor was the factory original so decided to skip that mod. To be fair, I still run the presence at almost off and it's still too harsh to dial any in - perhaps I'll experiment with a lower value for that one later.

I think I also skipped a couple of other Caps he suggested as I wanted to just do small incremental changes and see how each one contributed. The Bias Mod seems to be the most profound thing you can do to improve this amp though.

Also, try running it into a cab with 25w Greenbacks. I'm running two 2x12 cabs - one with V30s and one with Greens... I'm liking the combination a lot.
Cheers,
Sean

 

[inkwachemis]

hi garbagetruckdriver,

Great to hear you also did the bias mod, and liked it. You've also did Isaac's mods.
Before I've installed the bias mod, I did Isaac's mods, but when I installed the bias mod, I did undo Isaac's mods. (to start from the original starting point) Isaac's mods are great, and I really appreciate his great discoveries, but after the bias mod I think I don't need to redo the mods again, because I like the amp it sounds at this moment.

I am still very curious what preamp mod's you did to your amp. The mod I liked most was replacing the 39k to the 33k slope resistor.. Mayby some day I will redo the mod again

bye!

hey alie, are u still running the channel 1 clean mode in diode section? I recall in this mode, you measured it to be around 49ma. encounter any problems running it like this?

 

[alie123]

hi, I do like all modes in channel one.
Still experimenting with the different modes, and the settings I use depends on my mood..

I do use the fatclean mode with diode setting sometimes. No problem!! No redplating tubes or something. I know in clean mode with diode setting, it is biassed to high, .. but no problems so far, and I have used it a lot..

But currently I don't use the fat clean with diode, because I like the tite clean (with diodes) more than before. What I also find out is that after the bias mod I like the crunch setting of channel one most!. I like it so much that I use channel one 'crunch' with diodes, and channel2 tite gain (diodes) so at this settings I am safely within the right bias..

With my guitar volume backed off in channel1-crunch-diode, I can get a very nice clean sound, similiar to the clean modes of channel one. I like this a bit more than the clean modes itselves.. And I have more versatility .. !

Rock on!

 

[fbomb]

THIS THREAD IS USELESS WITHOUT CLIPS !

 

[donniecrump]

So you want clips ehh? Good news! I have recorded about 7 do far without the mod. I am going to cycle through all channels and modes without the mod installed then do the same with it installed. I will be posting these to youtube and then posting links to the audio clips.

I am also going to video the mod process and post that on youtube as well. If I don't make it back in a few weeks then I forgot to properly discharge the capacitors and I will post them when I get out of the hospital.

Donnie

 

[donniecrump]

I just used my Mansfield bias probe on my factory settings and it read 11 mA. I have read/heard that 30+ mA is a better range. Does Mesa ship these amps from the factory set that low or am I using my meter reader wrong?

Settings on my reader.
dial to 200m DC where the A- is. Not the A~
red lead plugged into hole that reads mA-)(-hfe.
black plug in com.

Settings on my amp.
Bold, 100w, speakers plugged in, power and standby on.

I tried the far left EL34 and the far right EL34 with the same readings.

Thanks,
Donnie