Metropoulos Forum

Having owned the 490 pups I very much prefer t tops for the angus sound. a stock 45 wont give you most of ang's sound either by the way. if you insert a ss plug in rectifier and good tubes you might get close to the last albums however

my stock 45 comes verry close to angus/bon sound,s.s. rect. just give you the fizzys,you don't know what your talking about,i have a-b-c-the 45-50-100, having owned several of each model. you can plug a sg/paf's into a 45 and you got angus's sound, i have owned all these amps!

terryy wrote:my stock 45 comes verry close to angus/bon sound,s.s. rect. just give you the fizzys,you don't know what your talking about,i have a-b-c-the 45-50-100, having owned several of each model. you can plug a sg/paf's into a 45 and you got angus's sound, i have owned all these amps!

Actually, I don't think a ss rectifier need to sound fizzy. I believe I know what I am talking about as I own all of these circuits and have tried many more. also, I've studied the ac/dc guitar sound for a long time, see for instance the long tread in the forum with interviews, pics etc

Cant we all just get along?

Anyway, thank's for everyone's input.

Just ordered...

2x .1 sozo's
the fancy looking blue 220uf cathod cap and an accompanying 820 resistor
a new CC 820 resistor, as I'll be removing the .68uf cap from v2 and will need a full length resistor
2x 32x32uf cans

I guess I should change the thread from being AC/DC oriented to just "JMP50 to JTM50 Conversion" ?

What difference would changing the resistors from carbon comp. to carbon film make?

Spodeeodee wrote:What difference would changing the resistors from carbon comp. to carbon film make?

less breakup, more of a classic plexi tone

I always thought the AC/DC tone was a pretty clean tone, just really cranked.

I was able to make some progress this weekend

Filtering is now 32uf all around.

Changed PI output coupling caps to .1uf

Eliminated the .68uf V2b capacitor (man, I wont miss that thing)

And, I 've already switched to a shared cathode (330uf/820), and have a JTM tone stack.

This has brought the amp more inline with the sound I was hoping to achieve! It has lost the harshness and aggressiveness, and now has much more usable 'clean' sounds, and a more pleasant crunch.

I would definitely encourage anyone with a 50watt / 1987 model to experiment with this setup!

Now I now why people are so fond of the JTM50. Thanks especially to thousandshirts!

Roe wrote:

terryy wrote:i think angus's sg's had 490's through a jtm45 back with bon anyways, thats the ticket when i try to sound like angus back then. there are other trademark sounds you need a sg for as well w/490's, i can nail joey moelling's sound. tony iommi well the early days there was nothing but stock pups,but plug into what he was using for an amp,which i think was a marshall major.
50's definitely tipton and downings sound,tipton preferred sg's but i don't know what pups he was using,my guess would be a ceramic mag pup though.

ang used t-tops. old pics shows 100watters, no jtm45s. ang has stated that he used a bright sounding 100w plexi on the old records. this appears to hold true for the period from dirty deeds (1976) on.
high voltage sounds like a 45/100, but dirty deeds sounds like super lead. let there be rock is more elusive. could have been a middle booster.

Roe, do you have any idea which amp Angus used at the Paris gig, in '79? I'm talking about the "Let There Be Rock" movie, from the HTH tour. There seems to be 2 different mixes, one being soundboard and one being "live", or in the arena somehow. The all time great tone for me is the sound Angus gets just before Bad Boy Boogie in this movie.

I have the original VHS tape, but some versions I've heard of this audio sound a little too hot and distorted.

Anyone have a clue about this?

JDW3 wrote:

Roe wrote:

terryy wrote:i think angus's sg's had 490's through a jtm45 back with bon anyways, thats the ticket when i try to sound like angus back then. there are other trademark sounds you need a sg for as well w/490's, i can nail joey moelling's sound. tony iommi well the early days there was nothing but stock pups,but plug into what he was using for an amp,which i think was a marshall major.
50's definitely tipton and downings sound,tipton preferred sg's but i don't know what pups he was using,my guess would be a ceramic mag pup though.

ang used t-tops. old pics shows 100watters, no jtm45s. ang has stated that he used a bright sounding 100w plexi on the old records. this appears to hold true for the period from dirty deeds (1976) on.
high voltage sounds like a 45/100, but dirty deeds sounds like super lead. let there be rock is more elusive. could have been a middle booster.

Roe, do you have any idea which amp Angus used at the Paris gig, in '79? I'm talking about the "Let There Be Rock" movie, from the HTH tour. There seems to be 2 different mixes, one being soundboard and one being "live", or in the arena somehow. The all time great tone for me is the sound Angus gets just before Bad Boy Boogie in this movie.

I have the original VHS tape, but some versions I've heard of this audio sound a little too hot and distorted.

Anyone have a clue about this?

this show is released on CD as part of bonfire. sounds like 100watters and a booster to drive the long cable. the battery of the booster appears to die during rosie.

The latest incarnation of my 50 watt...

-Standard split cathode
-No V2 cathode cap
-JMP tonestack
-.1uf output couplers
- 32uf filtering all around
-100pf bright cap

I'm liking this better, but who knows what it might change to when I get bored next

Spodeeodee wrote:The latest incarnation of my 50 watt...

-Standard split cathode
-No V2 cathode cap
-JMP tonestack
-.1uf output couplers
- 32uf filtering all around
-100pf bright cap

I'm liking this better, but who knows what it might change to when I get bored next

Hey Spo, I just finished my Metro build (hopefully get pics up soon and clips) and it sounds great. It is a JMP 50 circuit and chassis, with JTM-45 PT and tube rectifier.

I have just what you stated above, except I still have my V2 cathode cap and .022 output couplers.

What did the .1 in coupling bring you? More bass? Darker?

My next move would possibly be removing the V2 cap. But to be honest, I may replace all the Sozos with something closer to a mustard cap. I run mine with the mids dimed, precence on 3/4 and treble on 6. Still trying to dial the upper mids in, but I've only been running it maybe 25 hours. Needs more break in time for sure.

I think the .1 coupler caps result in a more organic feel, more so than .022. The bass is not as tight, but not at all flubby.

I would suggest removing V2 cap and see what you think. I'm not a big fan of it personally. Sounds harsh when it's in there.

As for my EQ...

Bass: 2-3
Mid: 5
Treble: 6

I'm almost always plugged into the bright channel, which in my situation precludes any need for the presence knob (I only use that on the 'normal' channel).

I guess I can't really call it a JTM50 anymore, and it's really not a 1986 or 1987 either...hmmmmm.....

mwm523 wrote:Before you change it, I would suggest you play with your volume and eq settings a bit more. Specifically, turn it down a bit and then adjust your eq. The 50 watter I built did a pretty convincing AC/DC tone with the bright channel volume down around 4 - 5. A lot of people play AC/DC with too much dirt... Their tone is really pretty clean, just a bit of crunch on it, especially back in the '70s.

That is spot on.

I remember years ago I was talking to a guitarist that had way more knowledge than I will ever have and I asked him almost the same question.

He responded that their amps were pretty clean on the tone, just turned way up!
After he said that I listened again to some of their recordings and it all made sense.