Australian Amp modification - Jemsite
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post #1 of 10 (permalink) Old 01-16-2004, 08:16 PM Thread Starter
 
Join Date: Dec 2000
Location: Australia
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Australian Amp modification

Does anyone know where I can get my Marshall modified in Sydney?
I've found a few tech's that will re-tube the amp but won't actually modify it at all.

Can anyone help?

thanks,
wil..
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post #2 of 10 (permalink) Old 01-17-2004, 09:53 AM
 
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Location: Melbourne, Australia
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Try phoning Pro Audio in Canberra, they know everybody everywhere and probably supply parts to someone who does mods.
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post #3 of 10 (permalink) Old 01-17-2004, 02:31 PM
 
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What types of mod are you considering??? If you have a schematic most techs should do it for you!!
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post #4 of 10 (permalink) Old 01-17-2004, 07:40 PM Thread Starter
 
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Hi guys,

Thanks for the tips.

I've found one guy that's in Sydney (Megtronics) that said he'll pretty much do anything, but won't really venture into the mod side of things without knowing what the result will be. He actually said if I have the schematics of what someone else has done then he'll actually do it.

I remember reading about a place in the US that has a website which tells you the result of the mods and the cost. I wonder if they'll send a schematic over... hmmm...

Any suggestions on where to get some schematics?

I basically want to change the amp a little tonally. It's a DSL 100 watt head. There's basically not enough growl. I also want it to cut through a bit more.

I spoke to the guy about modding the footswitching too so I could actually switch, by foot, between the different modes within each channel. He said he could do that for sure.

But he doesn't really want to muck with the tone. Would changing the tubes from EL34's to something different do what I want?

wil..
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post #5 of 10 (permalink) Old 01-18-2004, 04:49 AM
 
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Quote:
Originally Posted by wilch
Hi guys,

Thanks for the tips.

I've found one guy that's in Sydney (Megtronics) that said he'll pretty much do anything, but won't really venture into the mod side of things without knowing what the result will be. He actually said if I have the schematics of what someone else has done then he'll actually do it.

I remember reading about a place in the US that has a website which tells you the result of the mods and the cost. I wonder if they'll send a schematic over... hmmm...

Any suggestions on where to get some schematics?

I basically want to change the amp a little tonally. It's a DSL 100 watt head. There's basically not enough growl. I also want it to cut through a bit more.

I spoke to the guy about modding the footswitching too so I could actually switch, by foot, between the different modes within each channel. He said he could do that for sure.

But he doesn't really want to muck with the tone. Would changing the tubes from EL34's to something different do what I want?

wil..
Try www.duncanamps.com they have loads of schematics of old and new amps.

If by 'more growl' you mean gain you could ask him to add an extra valve in front of the EQ with a cathode follower. That would increase gain. Upgrading the transformers will greatly improve the tone of he amp as well. For more cut I woud try a new speaker unless you want them to change your amp a quite a bit.
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post #6 of 10 (permalink) Old 01-18-2004, 03:37 PM Thread Starter
 
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Location: Australia
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thanks for the link power freak

I'm not sure if more gain with my amp will equal more growl. If I turn up the gain at the moment I just get fuzz.

wil..
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post #7 of 10 (permalink) Old 01-19-2004, 11:43 AM
 
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Quote:
Originally Posted by wilch
thanks for the link power freak

I'm not sure if more gain with my amp will equal more growl. If I turn up the gain at the moment I just get fuzz.

wil..
Try out a load of amps and you can copy the different types of gain control they all act differently.
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post #8 of 10 (permalink) Old 01-24-2004, 01:09 AM Thread Starter
 
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Location: Australia
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Just got back from "megtronics", that amp tech place I mentioned in the first post.

Took my amp in, and firstly changed all the EL34's as the old ones had been in there for far too long and were making popping and hissing noises. The guy then rebiased the amp (very easy to do btw!!! Now that I've seen it I could easily do it myself).

The left 2 tubes were running way too hot >120, while the right 2 were ok'ish at 80+.

Anyway, I plugged in. Immediate difference in tone. But still not the growl I wanted.

So he suggested we start pulling the preamp(I think that's what they are??) tubes, and substituting them for 12ax7 one by one.

Change the first, instantly different sort of gain. Change the second, GROWL! Change the next one, no change, but still GROWL! So I told him to change all four.

The ones the 12ax7's were replacing have "Yogoslavia ECC-83" written on them. Are the 12ax7's known to sound growlier?

Switch channels and I can get smooth lead sounds that I couldn't get before with this head.

I'm surprised. I didn't need to get it modified. The tubes in it were just really dead, and I needed the 12ax7's to be in there. I still have the same problem of loudness though. There is no way I can use this amp at bedroom volumes. It only starts to come "on song" with the volume at half-way, which is window shaking loud (even when run through a twin speaker cab).

I had to totally change the amp's EQ section too. I use to run the amp with the deep switch on, bass at 3, mid at 6, treb at 8, presence at 7, and tone switch off. Gain was and is still set at 5 on both channels.

Now I have the deep switch off, bass at 5, mid at 4.5, treb at 7, presence at 7, and tone switch on.

I'm liking the sound I'm getting again from this amp.
*wil wipes his forehead and sighs the sound, "phew"

wil..
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post #9 of 10 (permalink) Old 01-24-2004, 06:07 AM
 
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Quote:
Originally Posted by wilch
The ones the 12ax7's were replacing have "Yogoslavia ECC-83" written on them. Are the 12ax7's known to sound growlier?
12AX7 (Ecc83s) are deffinatly morre agressive than most common valves. They also have alot more gain, although for reverb circuits I like Ecc82s 12AX7s are my favvourite for the preamp.

By the way what preamp valves did you have before??? 12AU7s 12AT7s????

Freak
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post #10 of 10 (permalink) Old 01-25-2004, 07:14 PM Thread Starter
 
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hmmm...

The ones he removed actually had ECC-83 written on them. The new ones just have 12ax7 written on them (Russian Electro-harmonix brand).

I still have the ecc-83's in boxes.

I actually found that as the ecc-83's were removed the distortion became less fuzzzzz and more growl (which I prefer).

wil..
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