More gainclone questions :)

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Ok, so I've gotten all the parts for my gainclones except for the transformer, but that I gotta wait a while for it.

I've a few questions since I'm designing the chassis right now (drawing some plans).

First off, I know the amplifier themselves like VERY short wiring paths. Is the same true for the power supply? I'm thinking of having the AC power come into the back of the PS, have the fuse in the back as well, but I want to have the switch in the front. I also plan on having the transformer about in the middle, with the bridges towards back left/back right (where the DC out connections will be).

Will it be a problem that i'm running the wires from the fuse in the back, to the switch in front, to transformer in middle?

My second question is not regarding the PS, but regarding the amp itself.
Is it better that I have the V+/- DC inputs on the amp farther away from the RCA inputs and the outputs for the speaker? or does it not make a difference?

Thank You

edit: oh yeah, and will having the V+ and V- inputs farther away from the outputs (and the actual lm3875s/rest of the circuit) from the amp cause an adverse effect as opposed to having them close to the speaker outputs/the actual circuit
 
elizard said:
Will it be a problem that i'm running the wires from the fuse in the back, to the switch in front, to transformer in middle?

My second question is not regarding the PS, but regarding the amp itself.
Is it better that I have the V+/- DC inputs on the amp farther away from the RCA inputs and the outputs for the speaker? or does it not make a difference?


To the first question I don't think it really matters, just try to run power line on one side and wires to the bridge on the other.

The second question: I don't think it matters as well. You might arrange your sockets and jacks and posts in most peculiar way, but all the wires meet at the chip anyway.;)

By that I mean that signal, as well as output and power all run side by side in the chip, so who really cares how they positioned on the rear panel. I try to choose the most eye pleasing arrangement.
 
now if only i could find a source for 1/8"-1/4" aluminum panels, i'd be all set!!!

anyone know how much a 2' by 4' would cost new??? i hear MAD expensive ..

i'm gonna have to make some calls tomorrow, see if i can find a place that sells them used .. scrap yard or somethin
 
Peter Daniel said:


I thought you are building a gainclone. Why you need so much material?;)


Sheesh, pot calling the kettle black if I ever heard it ;).

elizard,
Just to give you fair warning, it took me 1 day to do my wiring and about 8 days to make my case all out of aluminum and one piece of black acrylic. If you can do it, think about fronts and backs of aluminum and nice wood side panels. A little easier to work with and more forgiving. You won't need the extensive heatsinking capabilities of an all aluminum case so you're free to try other things. One guy in here put his first try in cardboard boxes. :nod:
On a side note, I dug out my 541 prototype and started messing with it again. I'll try and listen to them again and see why Pinkmouse likes them so much ;) Maybe try them with a smaller opamp buffer stage on a recommendation of another member.
 
well i was thinking of smaller boxes first, then i started thinking of adding weight to it ..

now here's what i got in mind (after reading these posts)

I have a case from a dvd player that doesn't work (the lens or reflector is toast .. don't feel like payin to fix it, it was a cheap player to boot

Peter .. would you mind telling me the dimensions of the torroid? Specifically the height and diameter is what i'm looking for .. i want to know if i can fit it in there :)

secondly, as someone suggested a wood case would be good ..
now .. small problem .. does it need shielding first of all? and if so, how can i provide shielding?
and does it need a metal part for ground? could i make the back out of a piece of aluminum or whatever metal i can get ahold of bolted to a piece of wood maybe?
does that sound reasonable?
or maybe even like put a sheet of metal on the botton of the case itself (inside) so that its not visible? (for grounding purposes)

Oh, also, do you think I should wire everything and construct everything before I get the transformer, or wait till i get it?

Thanks guys .. couldn't do this without your help! :)
 
The old dvd player case is a good idea and something I am doing for a 5ch HT GC I am in the process of putting together. Most of my experiments on GCs have been going in that direction but seems I will be doing some more. ;) It will save you time and money and with some care look pretty sharp. I wouldn't worry to much about shielding as I have all of my components in one case together and don't have any problems. You really only need a piece of 8" aluminum angle or an aluminum base to bolt the chips to. You should wait to wire everything until the case is done or near done. Put your diodes together into bridges, just wait until your case takes shape before you start drilling holes for your binding posts and RCA jacks. You can do a full size paper layout and get your orientation and dimensions sorted out first too. For the transformer specs go to the Plitron site. Under the standard transformer is a mechanical table with the dimensions of all their transformers.
 
well .. maybe i'll look for a bigger case, maybe i'll "slightly" modify the current one by extruding the bottom/top a little ..
or .. maybe i'll just use it without the top for a while :) .... bad idea, but hey :)

now .. if my VCR was broken .. that'd be awesome! :)

so my idea is to use the dvd player case, but put a panel of wood for the rear .. that way i can bolt everything to it ..
maybe in the future i'll construct an actual wood case for it ..

gotta plan out a couple cases for the monoblocks now .. still debating one case vs. two cases :)
 
beeautiful!!! :)

i just solved my problem of torroid not fitting ...
i'm gonna go for an interesting idea ... it'll either make my setup, or look really weird and ugly ..
and then i'll love it even more because i'll call it "unique" .. and "special" (yea yea like my mommy calls me :p)

i'm gonna make the torroid protrude about 3cm out of the case, and i will build a protective grille around it .. i would have gone for plexiglass/acrylic/glass/something that's seethrogugh, but can't get that as readily as i can a grille .. plus attaching it to the rest of the case would be an adventure in its own :)

now .. that takes care of my PS case worries .. now onto thinkin up of a case for the amp itself :)
wood i think will be my easiest solution .. maybe it'll be decent lookin too :)
 
Peter, another question for you :)

on your schematic i see you wound extra 6 windings (i think) around the torroid to get the power for the LED ..

to accomplish this, did you just use insulated 24ish gauge wire and wind it 6 times around the transformer? and is this for the 400VA torroid???

because i'd love to have a nice blue led for the power supply :)

reason i ask, i just read an article on ESP about transformers, and the way it explained winding extra windings is just use isolated bell wire and do X windings .. is that right? no other modifications required?
can i use the cat5e cable (which is 24 gauge)? or some other cable that i should use?
any suggestions
or should i not attempt this at this time?
 
elizard,
I did the same thing as Peter but with 8 wraps of 26AWG. I also used a load resistor before the LED @ 220ohms, but any resistor 100-300 ohms should work. You can get a three spool pack of magnet wire from Rat Shack for $3 which has what you need for these things. Wrap you winding with some clear packing tape to keep it from shifting. If its to bright, take a winding off and add a little more resistance. Some of those blue LEDs will light up the room and put spots in your vision sitting in front of them. :cool:
The transformer idea sounds interesting.
 
allright .. that makes sense

so basically its the windings, no need for anything but the led and the resistor???

also, i just checked radioshack, they carry 22/26/30g magnet wire (in a 3pack, one of each)
can i use 22g? i guess i could eh?

also i assume i have to make sure the wires don't overlap?
do i need to spread the windings around the ENTIRE circle? or can i concentrate them in like 1/4 of the circle? (the donut actually ..)

and packing tape works? it'll withstand the heat???
 
I tried something last night with the 541 prototype. I kept the pot in and hooked the amp up behind my preamp. It picked up more fullness(more than the LMs) but got a little to bright. The brightness might be curable with some component swaps. Whats the point? Glad you asked.. No hum. My LM amp always suffered from a low level (uncurable) ground loop hum when hooked up to the pre. Both the prototypes were in the exact same configuration when I tried this but for some reason the 541 is very quiet in the configuration.
Al, have you notice this difference in amp characteristics in your testing? I was thinking about a low level opamp before the main chip to try to control the hum but with the 541 not exhibiting this problem I might look at using it or one of its kin to work with my A/V pre/pro in a multi-channel amp.
Strange, Huh? ;)
 
elizard,
With such a low level you can use the 30AWG no prob. And you can put it right in the area you need closest to the LED, wound right next to each other as well. What heat? You using a pretty big transformer that I doubt will get even warm unless you're going to "Rock and roll all nite". sigh, I kind of miss KISS. Great music, great controversies. I guess they're kind of tame nowadays.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.