900 MK3 2500 update...

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Adrian R

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So like I have owned this amp for nearly two months and I think I now really got it sounding great... very 800 like...but with more gain...

I replaced all the pots with new ones from Marshall...identical to stock...
Replaced the filter caps with ARS LCR clones...sound identical imo
Replaced bias caps, had network adjusted to get a nice warm bias with EL34s. Didn't have enough range stock.
Installed a 3-4H Heyboer 100mA choke... similar to what the 2204s use.

Well, was not all that pleased. Sounded good, but it sagged too much...just didn't feel right. Nice clean tones.

So I had the Heyboer 100mA choke swapped out for a 3H 250mA choke...

That was the difference. Man, what a change. Now it sound great! Very Marshall authentic...hard to distinguish from a 2204. Plenty of punch... especially with the MV at 4 and above.'

It likes OD pedals. I use my trusty FD2 with it like I do with the DSLs. That was the ticket. With the two gain controls, plus the pedal, man you can dial in a bunch of different gain textures...really versatile..

However, I noticed you have to keep the sensitivity control on the low side to avoid unwanted noise... but you don't need much for to really affect the tone. Adds a great deal of body... I keep it at around 2-3 max. Sounds killer with the pedal engaged. This amp is a keeper...and a steal compared to what current 2204s sell for.

I bet this head would sound awesome with the Hot Mod V2!!
 

Gutch220

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Maybe somebody can explain why a 3-4H 100mA choke sounds so different than a 3H 250mA choke. The H is barely different while the current handling is significantly more

I would be interested in hearing this.
 

FleshOnGear

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Maybe somebody can explain why a 3-4H 100mA choke sounds so different than a 3H 250mA choke. The H is barely different while the current handling is significantly more

I would be interested in hearing this.
Perhaps the higher current handling equates to lower DCR, and the dc resistance of the 100mA choke was causing the extra sag?
 

FleshOnGear

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Does this normally happen?
Almost all of the specs I’ve seen show an inverse relationship between current handling and DCR. I assume this is because chokes that handle more current use thicker wire.
 
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