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I just finished my sIII build and the normal side just sounds awesome! I played around with the MV on the TMB side and it gets kind of chirpy and I can't get that marshal crunch like I can on the normal side. What should I expect the TMB side to sound like?
Thanks
Don

My TMB side sounds great and I can still get good crunch from about 5 up, sounds like you may have a problem on that channel.

Yea it was kind of a dumb question after hearing the clips... I just wondered if I needed to tweak something. The normal side just sounds so great. Could the fact that I omitted R8 from the circuit do this? I'm going to wire in R8 and see if that helps anything. I just left it out since it was the first suggested tone tweak and leaving it out was easier that putting it in and then removing it.
thanks

I must admit I have not bothered with the tone tweaks at all as I am more than happy with the stock sound.
Nigel

FWIW, I recommend that you start with a known build - then tweak if you think it's necessay. Put R8 back in and recheck the pin connections to V1 and maybe resolder the input jacks.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

The TMB channel of the sIII will deliver good crunch with medium to higher output pickups. It will also clean up very nicely when you back off on the guitar volume. That is one of the reasons I like it so much. And yes the normal channel is wicked.

yea I think that is what totally blew me away about this amp was I was expecting the normal side to be relatively tame and the side with the MV having the real distortion.. Boy was I in for a surprise!
Hell I might have built something far simpler with only one channel if I knew it was going to sound this great.

Try jumping the channels for some really wicked sounds.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Did you put it back in? How does is sound now?

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

sorry, kids and wife keeping me from the garage... I plan to resume this next week after the holidays. This amp is so loud I think someone is going to call the cops on me!
thanks
Don

Ok, I know everybody is busy burpin’ and fartin’ the Christmas dinner and may not be online but I am going to ask anyway.. Getting ready to work on the tmb side and found that I probably need to stop using bargain bin parts and mixing matching.... I put a 4700pf silver mica in place of the .0047uf Mallory 150 on the tmb volume pot... Don’t know if this would cause a problem since technically 4700pf is .0047uf but I am going to replace that with an orange drop since that’s all I have. I am going to put in R8 and I notice that the one terminal is going to the ground bus and this R8 is going to the ground bus. Wouldn't it be equivalent to just jumper R8 to the other lug? Oh well I will follow the drawing and let you know the results. I will also have my pin voltages posted shortly.
Thanks
Don

If you are talking about C1 then I have used an Orange Drop here successfully.



I have R8 on the TMB volume across the two lugs with the outside lug going to ground no problems.
Nigel

Ok, cool... I have installed R8 and replaced the C1 with a 400v orange drop and I fiddled around with the TMB side some more... How far should I be able to turn up the MV before things start getting out of control? I have some serious crackle and fizzle coming out if I turn it up past 4. It seems to happen mostly on the lower chords. I dont know if it's my speaker or the tubes or what. when I turn it down I get a really good clean full sound that rings out beautifully, then I turn it up and all hell breaks loose. Do I take the voltages with the guitar plugged in or does it matter?
Thanks
Don

If I put in ear plugs, I can get both vol and MV up to 10 If you are getting crackle and fiz there is definately something not right. If it is only on the TMB side I would investigate V2 first, try replacing it with a known good tube. I have had 12AX7s that have serious microphonic properties at particular frequencies. If that does not prove anything, try tracing the TMB circuit and reflowing the solder joints, I have had a bad joint that was also subject to crackle due to vibration at a certain frequency (in fact it was on the sIII TMB)
Lastly, if you have used old resistors check them out, I reused a resistor from an old Hammond organ amp which crackled like mad.

When measuring your voltages I don't think it matters if you have a guitar plugged in unless you are measuring the input voltages.

Thanks for the help... I used mostly NOS CCs so I guess it's possible I have some bad ones or something.
here are my pin voltages that I could get with my meter on DC 1000v, tubes and speaker installed.. no guitar plugged in. (the snaps and pops scared the crap out of me)...

V1
---
1 144v
3 .95v
6 142.7v
8 0.9v

v2
---
1 173v
3 1.5v
6 250v
7 173v
8 172v

v3
---
1 213v
2 51v
3 72.8v
6 195v
8 72.8v

v4
---
2 28v
3 12.6v
7 342v
9 325v

v5
---
2 50v
3 12.6v
7 342v
9 326v

v6
---
1 308v
3 357v
7 306v

Reflow the input jacks connections and the parts up to V1. If the normal channel sounds good, then eliminate the TMB input to v1 first. Then focus on the tmb off board parts - reflow them after you're sure they are good. Then go to the board and check the TMB parts and then reflow the solder joints. IT might be the MV pot as well. You could try cleaning it with contact cleaner spray.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Thanks, will start on that tomorrow... I am assuming that since you didnt comment you think my voltages are good? they seem to be comparable to the ones listed on the 18w site.

There are sIII postings on this forum if you want to compare them. Go to viewtopic.php?t=416

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Ok, the reflow fixed it. I reflowed pretty much everything except the MV because I couldn't reach it. Little scratchy if I turn it while sustaining a power chord but I would rarely play while manipulating the pot.
This thing is totally rocking now I can turn it to 10. Wish it would go to 11 so I could be like Nigel.
Thanks guys!

Great news. Those cold solder joints will get you eventually, so good thing you found it now while the iron's hot! If a solder joint does not have a nice shine to it, or looks dull, the suspect it and reflow it again with plenty of heat, 2 seconds once it starts to flow, with some extra solder.

Nice to hear how great it sounds. We are all looking forward to pics/clips. Let me know if you need help posting.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps