[bozebuttons]

Quote:

Originally Posted by NoValidTitle /img/forum/go_quote.gif Just the two people I wanted to reply! Thanks that info helps a ton. Boze out of curiosity could you post a pic of the front of your amp? Looking at the pictures it looks like you have some crazy front panel setup.

Just a standard maestro face plate with no meter,a little beat up .I have a mint silver Sha1 faceplate I was thinking of installing.

 

[NoValidTitle]

Quote:

Originally Posted by bozebuttons /img/forum/go_quote.gif Just a standard maestro face plate with no meter,a little beat up .I have a mint silver Sha1 faceplate I was thinking of installing.

Ahh makes sense, I saw more then two knobs and was like What? googled the maestro front and saw. Has anyone made a custom Melos housing? I really want to for the hell of it but I'm worried about how hot this sucker gets. A plexi top on a Maestrobator would be sick IMO.

 

[NoValidTitle]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif the 4 HUGE tall caps near the front of the case are the output caps for the preamp stage. in my amp they are solens, stock was a "melos" branded part whcih i have no idea where it came from

so these only matter if I'm using the amp as a preamp and not a head amp?

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif i think you are talking about the film cap. i dont know where carlo put it on the bosebuttons amp on my MAR amp, it came directly across the DC side of the HV recifyer. i removed it from there and replaced the last electrolytic with it.

are you saying you put it in place of the larger cap that is missing from your board by the Melos logo? I assume you just soldered the leads through the bottom?

oh and does anyone have any insight on the resistors? It doesn't look like my budget will be broken with just caps so there is room to by more.

Once I fully understand the huge film cap and pre amp caps I might add those to the list but here is what I have so far...

----------------------------------------------
8x Auricap 62036 1.0 200v $9.50
1x Blackgate 60194 FK 2200 35v$24.50
1x Blackgate 60224 Std 100 160v$13.50 <--Anything better??
2x Blackgate 60089 NX 1000 25v$12.50
----------------------------------------------

 

[nikongod]

Quote:

Originally Posted by NoValidTitle /img/forum/go_quote.gif so these only matter if I'm using the amp as a preamp and not a head amp?

yeppo.
if you have no intention of using as premp, ignore the bottom half of the board. basically everything between the tubes and the edge of the board. there is 1 part that may efect sound "down there" but i dunno, because i have not changed the resistors for the cathode bias thingy.

Quote:

are you saying you put it in place of the larger cap that is missing from your board by the Melos logo? I assume you just soldered the leads through the bottom?

yeppo. i soldered VERY long wires to the cap, whic was in a different place on my melos (near the IEC connector in the back) where it was on boze's amp looks better, but i added a choke there in place of a resistor. choke>resistor for PSU. choke=$50, resistor=$1.50 $50>>1.5

the 100-180ohm (depends on what day of what week your melos was made) resistor in the middle of the PSU is good to change for a choke. mosfet regulators CAN do their thing with a resistor between them and the recifyer, but do it better with a choke.
Quote:

oh and does anyone have any insight on the resistors? It doesn't look like my budget will be broken with just caps so there is room to by more.

your budget will QUICKLY be busted buying tantalium resistors

maybe your budget is really nowhere near busting.... i replaced a bunch of the PSU resistors out of superstesion more than anything. they are pretty old, some of them crumbled as i removed them. same part sizes, nice quality.
Quote:

Once I fully understand the huge film cap and pre amp caps I might add those to the list but here is what I have so far... ---------------------------------------------- 8x Auricap 62036 1.0 200v $9.50 1x Blackgate 60194 FK 2200 35v$24.50 1x Blackgate 60224 Std 100 160v$13.50 <--Anything better?? 2x Blackgate 60089 NX 1000 25v$12.50 ----------------------------------------------

im not a fan of standard grade black gates (from third hand info) they are more expensive than everyone elses "barely botique cap" and dont really have a much better sound. if you had planned to use this cap as the last cap in the HV suply, that is where i used the film. i am a film fanatic. electrolytics are soooooo good that people bypass them with film to make them sound more like film

you can reduce parts count...
i personally believe in not using more caps than necessary from the same manufacturer, for the 2 after the LV regulators, i used a 470uf/50V blackgate FK, and a nichon muze in some big size (dont rember size, about 1000-2000uf) i left the 2 caps before the LV regulator stock. i did not use the film caps for bypass. i guess i have a weird system, but others use it too. i dont like to bypass electrolytic with film. when i can i use a full film cap, when i cant i use just a good e-lytic

 

[bam022]

A plexi top would look pretty awesome, I agree, but I wonder the degree to which letting in too much light pollution would mess with the Melos's pho-tentiometer (the light controlled volume control)?

When changing out tubes last month, at a point in the day when the sun was shining into my Melos I was baffled by why cranking the volume had no effect.

Outside of that though, I agree that a plexi top would be sick.

 

[NoValidTitle]

Quote:

Originally Posted by bam022 /img/forum/go_quote.gif A plexi top would look pretty awesome, I agree, but I wonder the degree to which letting in too much light pollution would mess with the Melos's pho-tentiometer (the light controlled volume control)? When changing out tubes last month, at a point in the day when the sun was shining into my Melos I was baffled by why cranking the volume had no effect. Outside of that though, I agree that a plexi top would be sick.

I think I might try the plexi window and see what comes of it, and I'll be taking that blasted pho-tentiometer out anyway.

 

[bam022]

What is with all the pho-tentiometer hate? Sure, it might be responsible for some background noise on the amp, but it has to be one of the coolest ideas ever: volume control by a light. Man, I can't get over how cool that is.

Also, I wonder if the pho-tentiometer has value when using the Melos as a passive pre-amp, which I intend to do at some point.

 

[dsavitsk]

This amp is really a mess -- not mine, the design. It's a wonder it works at all

Anyhow, I am tinkering around with a SHA-1. The only schematic I have is for a SHA-Gold (are there any SHA-1 schematics floating around?), and while they are pretty similar, there are also a few differences. The Schematic shows the negative input going to the second grid of the tube. the SHA-1, not being balanced, seems to just leave grid #2 out of the circuit. Is this correct? Anyone tried running them in parallel?

Are the input caps necessary -- that is, the grids seem to not be connected to ground, so the caps seem to be necessary to the biasing scheme, but I thought I'd check. If they are, the schematic shows 1uF (mine uses some lovely ceramic discs here.) Anyone gotten away with a smaller value?

Other than replacing coupling caps, moving the grid stoppers closer to the grids so they actually work, and replacing a few of the solid state PS caps, anything else essential to do?

 

[nikongod]

Quote:

Originally Posted by dsavitsk /img/forum/go_quote.gif This amp is really a mess -- not mine, the design. It's a wonder it works at all

amen brother.
the sha-gold is even harder to reverse engineer. the sha-1 is laid out much better.
Quote:

Anyhow, I am tinkering around with a SHA-1. The only schematic I have is for a SHA-Gold (are there any SHA-1 schematics floating around?), and while they are pretty similar, there are also a few differences. The Schematic shows the negative input going to the second grid of the tube. the SHA-1, not being balanced, seems to just leave grid #2 out of the circuit. Is this correct? Anyone tried running them in parallel?

for the tubes, BOTH have EXACTLY the same tube design. the grid of the second half of the tube is grounded through a cap in both.
Quote:

Are the input caps necessary -- that is, the grids seem to not be connected to ground, so the caps seem to be necessary to the biasing scheme, but I thought I'd check. If they are, the schematic shows 1uF (mine uses some lovely ceramic discs here.) Anyone gotten away with a smaller value?

im not totally sure if they are necessary or not. they theoretically should not be, but may be. CARLO mentioned removing them, and i tried it but it didnt work (weird oscilation and noise) but that may have been because i did 2 mods at once, and messed up the other.

anyways, the actual minimum value for the input caps is fricking small. i use 0.22uf on my sha-1 with no ill effects.
Quote:

Other than replacing coupling caps, moving the grid stoppers closer to the grids so they actually work, and replacing a few of the solid state PS caps, anything else essential to do?

not really essential, but the "choke mod" should do wonders to the sha-1. replace the resistor in the HV supply with an inductor. i have not tried on mine because i recycled my 5h/125ma choke back to my big tube amp. it did wonders to the gold. if you have the parts sitting around try it out.

i also have a VERY experimental mod. parallel the diode that sets the voltage for the regulator/filter mosfet with a film cap. i have not tried it, but it should be SWEEEET. on my amp, i replaced the last cap in the HV supply with a 100uf film cap, and there is some hiss. i suspect it is either diode noise or junk that the inductor would kill. the cap there cant hurt.

 

[dsavitsk]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif the sha-1 is laid out much better.

It looks like if you pulled off the timer and the preamp output caps, it is set up so that the pot could be board mounted.

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif for the tubes, BOTH have EXACTLY the same tube design. the grid of the second half of the tube is grounded through a cap in both.

I see -- more ceramic discs. It looks like the RC filter has a 1M resistor to "ground", so small caps are okay. I've got some 0.1 Teflons and some VitQ's to try there.

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif im not totally sure if they are necessary or not. they theoretically should not be, but may be. CARLO mentioned removing them, and i tried it but it didnt work (weird oscilation and noise) but that may have been because i did 2 mods at once, and messed up the other.

I'll take some measurements and see if it is reasonable to do, but looking more closely at the schematic, I think the answer is probably not.


Quote:

Originally Posted by nikongod /img/forum/go_quote.gif not really essential, but the "choke mod" should do wonders to the sha-1. replace the resistor in the HV supply with an inductor. i have not tried on mine because i recycled my 5h/125ma choke back to my big tube amp. it did wonders to the gold. if you have the parts sitting around try it out.

Do you know the current draw? My guess would be in the 40-50mA range, but I'd be curious if you have measured it.

 

[DRCope]

Hi Guys,

I have a SHA-1 that's been in a coma for several years and I'd like to get it back up on its feet for a few different purposes, mostly revolving around a recently acquired Otari MX-5050 reel-to-reel deck. I spend my days working on my computer while my step-son, who works nights, sleeps, prevents me from running my main rig. I'm listening using the 'phone jack on the Otari itself and it's ok, but nothing to write home about.

Blah, blah, blah.... the question is, where can I/should I send the SHA-1 for resuscitation? I may want to have it jump through fancier hoops at some point, but just breathing/functioning would be great right now.

I've seen Modular Electronics in Atlanta mentioned as well as Mark Porzelli, although I don't know if he does servicing or just mods or what. . . . Anyone else? I'm located in CT, so if there's anyone in New England I'd prefer that, all things being equal, but really I just want reliable good quality work. . . .

Thanks!

 

[Computerpro3]

Quote:

Originally Posted by DRCope /img/forum/go_quote.gif Hi Guys, I have a SHA-1 that's been in a coma for several years and I'd like to get it back up on its feet for a few different purposes, mostly revolving around a recently acquired Otari MX-5050 reel-to-reel deck. I spend my days working on my computer while my step-son, who works nights, sleeps, prevents me from running my main rig. I'm listening using the 'phone jack on the Otari itself and it's ok, but nothing to write home about. Blah, blah, blah.... the question is, where can I/should I send the SHA-1 for resuscitation? I may want to have it jump through fancier hoops at some point, but just breathing/functioning would be great right now. I've seen Modular Electronics in Atlanta mentioned as well as Mark Porzelli, although I don't know if he does servicing or just mods or what. . . . Anyone else? I'm located in CT, so if there's anyone in New England I'd prefer that, all things being equal, but really I just want reliable good quality work. . . . Thanks!

Depends on what's wrong. If it's something really simple like a loose ground or cap replacements I might be able to figure it out. I'm no electrical engineer, but I've worked on two Melos amps before so I know some of the most common problems. Alternately, if someone can diagnose it for you and tell you what's wrong, I can do all of the soldering for you (I'm right in CT too) and get it running again.

What symptoms does the amp have? Just not even powering up?

 

[F1GTR]

Quote:

Originally Posted by DRCope /img/forum/go_quote.gif Hi Guys, I have a SHA-1 that's been in a coma for several years and I'd like to get it back up on its feet for a few different purposes, mostly revolving around a recently acquired Otari MX-5050 reel-to-reel deck. I spend my days working on my computer while my step-son, who works nights, sleeps, prevents me from running my main rig. I'm listening using the 'phone jack on the Otari itself and it's ok, but nothing to write home about. Blah, blah, blah.... the question is, where can I/should I send the SHA-1 for resuscitation? I may want to have it jump through fancier hoops at some point, but just breathing/functioning would be great right now. I've seen Modular Electronics in Atlanta mentioned as well as Mark Porzelli, although I don't know if he does servicing or just mods or what. . . . Anyone else? I'm located in CT, so if there's anyone in New England I'd prefer that, all things being equal, but really I just want reliable good quality work. . . . Thanks!

Yeah there's a whole lot of us waiting and hoping for the same thing.

One of these days now, this site is supposed to go active. I'm not positive it is 100% authentic yet, especially considering we're already in to the summer and the site hasn't been updated in about 2-3 months, but it sounds promising.

http://www.melosinnovations.com/

Here is a thread where we discussed/prayed that they would open their doors soon.

http://www.head-fi.org/forums/showth...ighlight=melos

 

[jp11801]

Nikongod, what are your thoughts on the v-caps you installed inbetween the tubes? I have no skills as a modder but am thinking of getting my sha gold ref worked over.

PS I have the MAR modded one at the moment but I have heard the solens are not the best caps

 

[nikongod]

Quote:

Originally Posted by jp11801 /img/forum/go_quote.gif Nikongod, what are your thoughts on the v-caps you installed inbetween the tubes? I have no skills as a modder but am thinking of getting my sha gold ref worked over. PS I have the MAR modded one at the moment but I have heard the solens are not the best caps

i have not heard other amps with other "good" interstage caps, but the v-caps are superb.

the solens that MAR seems to love are not all that hot. they are better than what MELOS used... i would not call them veiled, but blurred. the transition to better caps (input and interstage) was pretty shocking.