ECP Torpedo III [indexed in first post]

I have no opinion, positive or negative, about them. I am generally skeptical of parts making much of a difference unless I have reason to understand why. That applies to all parts, not just these.

 

I snagged irc gs3 100k 3 watt resistors, wonder how the size compares.

 

Never heard about those resistors, do you have a link to info?

 

Odd. I have never read Doug nor TomB express a "serious dislike" for AMRG resistors.

Here's a link to a datasheet for GS3 resistors referenced by @Mr.Sneis : http://www.mouser.com/ds/2/414/gs-461130.pdf

 

So when you stated they are just standard $ 0.15 resistors put in a metal tube that was not an opinion..? Never mind, I should leave the topic.

I just think you guys give these components a hard time for no reason at all. Honestly it makes me sad and I loose my motivation to continue work on this amp, since those of us who use upgraded plate loading resistors in our T3's hear real improvement in sound. I think people get's scared of from experimenting with a design team being skeptical on the topic.

But the designers are always right, so I'll leave it and not mention plate loading resistors again.

 

Morten,

As you well know, I had agreed to try them. You and I exchanged e-mails about it. I even had them ordered from that Ebay guy in Vietnam, but he came back and said he didn't have 100K. This was after actually ordering them from PartsConnexion first, only to have them tell me they didn't have them, too. So, I waited because I knew Brencho was sending me some to put in his amp. I fully agreed to do it and was looking forward to a comparison ... until I actually saw them and how big they are. After putting in the Tube CCS boards and the four Output CCS boards, I was doubly reluctant to try to fit those things in there and told him so last night. Still, he was paying for it and I readily agreed to go forward with them today.

After the experience I had, though, NO. Pops and crackles are mighty scary at 200+ Volts. Maybe you are used to solving things like that, as good a builder as you are. I remember the photos of your builds - very impressive!

Anyway, maybe I'll calm down after a few days, but it was not an experience I want to go through again. Despite having built over a dozen of these so far, I'm always a bit scared when working on someone else's prized possession. I need to keep things simple, conservative, and dependable in situations like that.

So, it was no unusual bias against the resistors - just an issue seeing how big they really are and then to have the worst happen in trying to put them in.

 

I think you are reading my tone all wrong. Perhaps I am expressing it all wrong. I have not tried them, and my experience with expensive resistors has been underwhelming in the past, so I remain skeptical.

Skeptical does not mean that I do not believe your experience is genuine, or that I do not think it is possible that these resistors make a difference. It means I want to see more evidence. I have a PhD in a scientific field, and I tend to be the sort that likes to see evidence beyond one person's experience, no matter how reliable that one person may be, before drawing a conclusion. That should not stop others from experimenting. Indeed, it should encourage it. I consider your findings pilot data that warrants more investigation. But that is not the same as convincing me that we should change the kits.

I am sorry that your feelings are hurt. That is definitely not my intention. I am not trying to pick on you, or Amtrans, or anything of the sort. And we appreciate your experimentation and contribution.

 

I hope this isn't pouring fuel on the fire, but after re-reading some of this, I decided to measure the Amtrans resistors that I removed. There is no break in any of them. They all measure approximately 100K and wiggling the leads give no indication of a change in resistance.

So I'm not sure what was going on.

 

Were they shorting to the case?

 

I don't think the case is conductive, i have the leads bent straight against the edge and everything works fine. But it might be possible there is a conductive material under the coating of the case and that caused a short.

Edit: Seems the outer case is anodized aluminium, that might definitely cause problems, i'm gonna sort that out on my end asap.
http://www.acoustic-dimension.com/amtrans/Amtrans-amrg-carbon-film-resistors-datasheet.pdf

 

The anodized film should not be conductive.

 

I know not unless it's scratched..

 

Thanks for measuring them post-removal @TomB good to know it wasn't just a broken resistor!

 

OK, I read Doug's post and I assume he means the T3 case (no way), then I read Riotvan's and, "Oh sh*t." That would mean that Morten's method of bending is the only thing that might be valid. Plus, If you screw around with them much and then get them flush to the PCB - like I do - they may be contacting another trace or pad. Heck, those un-used diode pads are right next to a couple of the positions where I rolled them over to make room.

Dang ...

 

Seems like the length of the amrg's is a challenge at 18mm x 8mm. The IRC's are cheap enough to try and measure a little smaller at 13.1 x 5.7. My experience with them is limited only in my Melos amp for tube plate load when compared with koa speer spr2's (supposedly kiwame is the same). I haven't installed the IRC's yet..

I am a little embarrassed to say, I am hesitant on the new output CCS boards due to the cost being a little more than I expected SO I will hold off for further impressions from you guys before taking the plunge!

 

Drats, well it's good to have a possible explanation here, though that anodized case really ought not be conductive ... Nevertheless I'll say a few Hail Marys after installing my output CCS boards and before turning the amp on again for the first time. I did mount mine proud of the PCB.

 

I think i will mount those resistors vertically and insulate the leads with teflon, maybe make a spacer and glue them in place as well.

 

Please provide pics, if possible.. I'd like to add this to the index (1st post). Thanks!

 

Sure, just hope there are no risks of picking up interference or anything like that. Perhaps @dsavitsk can shed a light on that

 

I'm sure Dough means the case of the Amstrans resistors. The case of the resistors are made of conductive aluminum and we can't rely on a thin layer of anodizing to do the insulation. That's why I do the bend with the safe distance between the legs and the housing, and I keep a safe distance between the housing and the PCB (pictures of my installation earlier in the thread somewhere). If there is no space for this with the output CCS installed it's a good idea to mount them vertically as suggested above = one leg very short so the resistor housing is vertical just a few mm above the PCB and then a long leg goin to the other hole in the PCB. On this long leg it would be good with some teflon tubing or equal for insulation.

For me it's time now to go offline and enjoy some music and this wonderful amp, I have given what I can in squeezing the best possible sound out of the T3...