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Eddie Current DIY amplifier "Monolith" - Page 5

post #61 of 171

I think what spritzer is saying is why waste money on thousands of dollars on an amp not designed properly, not following proper engineering when you can build a similar amp following the right principles, that uses the base schematics of what that other amp is based on, save heaps of money and have good sound as well. 

post #62 of 171
Quote:
Originally Posted by DefQon View Post

I think what spritzer is saying is why waste money on thousands of dollars on an amp not designed properly, not following proper engineering when you can build a similar amp following the right principles, that uses the base schematics of what that other amp is based on, save heaps of money and have good sound as well. 

 

I'm happy to wait for Birgir to reply, thanks... but I appreciate your interpretation.

 

A couple of hundred dollars is a far cry from thousands, and luckily I am not constrained by budget.  I am lucky to be able to not have to restrict myself to a single amp, or building project for that matter.  

 

After I try this amp both cap coupled and transformer coupled and see what can be done with other changes like those that have been suggested I will likely give it away or use it to drive some little speakers in my kitchen or garage.  It will get used, or it will become a source of donor parts for other little projects.  

 

After I've gained more building experience and learned a lot about what this amp topology will deliver (and won't deliver) I won't feel like I've wasted my money, even if it's not the best sounding amp in the world. 

 

I'm not sure if you're speaking about the Darkstar or the Monolith when you make the accusations of improper engineering and improper design?  I can only speak about the Monolith.  I certainly did not see Spritzer make that accusation. Being critical of OPAMP selection or encouraging addition of output bias in the design are critiques encouraging improvement to the circuit, but simply implying that Craig is not following proper engineering practices is a more serious accusation that's not warranted here, or at the least a little extreme.

 

I was reading a thread from 2009 last night where Birgir was being questioned for why he was doing something.  His reply was simply that he should be able to prove things for himself with his own ears and not follow whatever is written by the masses in threads here.  That's all I'm really wondering, why doesn't that apply to us all?

 

It's all been done before.  None of this is novel.  Why bother to build anything when I can just ask about it here and have the results explained to me?  

 

I don't want to keep killing this thread with this BS.  With any luck a moderator will see it and delete it all.  It's passing some time while parts are on order and we can get back to building, but i've got another three boards that I want to stuff this weekend and that's what I should be doing instead of wasting everyones time here.  Sorry for the distraction.

 

Hopefully those of you with good technical advice will continue to help here, but please leave the discouraging words for another thread.

post #63 of 171

I was referring to the Darkstar not this.

post #64 of 171

Thanks, sorry I misunderstood.

Cheers,
Chris

post #65 of 171

The Monolith is the Darkstar, no doubt about that.  Some small changes here and there but nothing that will make it suck any less than the RSA version.  Now I do think it's a good idea for Craig to offer this to people as debunking the myth of "magical" amps is very much required.  We did a similar board last year but the real intention was not to use it as an audio amp.  That said, I think it is well worth the effort when doing this stuff to improve on the original design to show just how wrong it was. 

 

Ift's fine that you are building this for shlt and giggles but people might think it is a high quality amp. which it clearly isn't.  jcx's post clearly stands then as to what's wrong with the general design and how it can be improved. 

post #66 of 171

Yeah given shipsupts price so far for the BOM parts and boards is so far at $200, this amp will be a good one to play around with. Interested but how much would need to be changed with the schematics to make it sound best?

post #67 of 171

I'm hoping less than the Dark Star!  bigsmile_face.gif

post #68 of 171

I guess what the gist of this all comes down to is.

 

With so many good designs out there, why would anyone willingly chose to build a bad one?confused_face_2.gif
 

post #69 of 171

Well is this a "bad one" lol, what constitutes a "bad one". Is a CMOY bad because is pretty much sucks? No, cause it has its purpose, and its funny in airports. This might not be the best sounding, but replicating a $2700 amp for under $300 is pretty funny.

post #70 of 171
Found a small error on the BOM.

The 4 ea. 5.5k 1/4 W resistors listed on the amp board need to go into R2, R9, R16, and R22

NOT R18

Schematic is right. Order quantities are ok.
post #71 of 171

Waiting for the transformers now.  Hoping customs doesn't hang on to them too long so I can get on with testing.

 

 

 

post #72 of 171

Looks smaller than I thought it would. When are the balanced ports going on?

post #73 of 171

I'm pretty tempted to throw some caps in there and run it while I wait for the transformers to be delivered.  Anyone else making progress?

 

I did test the PSU, all good.

post #74 of 171

Should start soldering my this week.
 

post #75 of 171

I threw a couple of caps and resistors in to get up and running tonight while I wait for the input transformers.  Wired up some balanced in and outs, mounted everything on a temporary wooden base and fired up without a hitch.  

 

It was sounding pretty good, right up until I pushed the gain up hard.  C7 (10uF 16V cap) on the -15V input side of the OPAMP blew in spectacular fashion, including a nice pop and fire.  

 

I don't see anything else damaged, but I'll have to do some poking to see what might be going on.  

 

For the LED I put a 24V green LED in with a 10k resistor (R23).  

 

I did get a chance to cut the input and raise the gain and it was absolutely silent.  I hope I can keep it that way when I add the coupling transformers and move it from the wood test base to the chassis!

 

Always good to get one running (sort of), but always frustrating to have to figure why we had a little arc and spark.

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