[JiggaD369]

I had some questions regarding the parts becuase I wanted to make sure I get the right stuff before I go ahead and order them. The amp will be used for AKG K701's. These are the parts Ive selected so far but please feel free to let me know if I should change them to something else. I want the best sound out of this and the K701 but I don't want to pay hundereds for it. I want to stay pretty close to the standard recommendations but whatever is the BEST POSSIBLE CHOICE, please let me know what to get because I have no clue how electronics work .

For the M3:

1. Trimpots - not sure which ones to get.
2. Resistors - Vishay RN55D
3. Caps - for the electrolytics I've chosen Panasonic FC and for the film, BC MKP.
4. OPamps - AD8065AR as per recommendations.
5. Heatsinks - 1.5". Do I need to get the mounting kits?
6. I wanted to have 2 inputs so what other stuff to I have to get other than a selector swtich? And what kind of selector swtich do I need?
7. Case - Par-Metal 12x8x2.
8. Hook-up wire - how much (length wise) is need?
9. Any other things I missed out?

For the STEPS:
1. I've gotten pretty much everything figured out except the resistors. The recommended values are not listed so can you please let me know which values I need for R1, R2, R3, and R4. Concerning the R4 value, I don't know what the VOUT will be. Sorry Im really electronic illterate but Im just starting out in this hobby.
2. I also dont know if i need 15VA or 25VA tranformer. Does it have anything to do with R4 value?
3. This is a stupid question but if i get a IEC inlet with a fuse holder in it, do also need a on-board fuse on the STEPS?

Thanx for all your help guys. I truly appreaciate it.

 

[n_maher]

Quote:

Originally Posted by JiggaD369 I want the best sound out of this and the K701 but I don't want to pay hundereds for it. I want to stay pretty close to the standard recommendations but whatever is the BEST POSSIBLE CHOICE, please let me know what to get because I have no clue how electronics work .

First, there are no real "standard" or "best possible" recommendations. Even the BOM that I put together is just an example of one way to build the amp. The degree to which you can tweak this amp is nearly endless and there is certainly no end to how much $$$ you could spend building it. But I'll try to address your questions as best I can, please understand that I'm not trying to be condesending in some of my answers but rather allow you to learn from my experiences with this hobby. Comments are in red.

Quote:

For the M3: 1. Trimpots - not sure which ones to get. I use the "Bourns" trimpots, I can't believe that you'd hear a difference if you used any of the values listed on AMB's site. 2. Resistors - Vishay RN55D Sounds fine to me. 3. Caps - for the electrolytics I've chosen Panasonic FC and for the film, BC MKP. Again, fine - there are other more "exotic" caps you could use but it's up to your ears to decide if they're worth it. 4. OPamps - AD8065AR as per recommendations. Sure, why not? Can't say I've used them in any amp so I have no idea how they'll sound. 5. Heatsinks - 1.5". Do I need to get the mounting kits? I would, just to be on the safe side. 6. I wanted to have 2 inputs so what other stuff to I have to get other than a selector swtich? And what kind of selector swtich do I need? This is where I'm going to recommend that you do some digging on your own. While I could lay out for you exactly how to do what you want you'll be much better off if you figure some of it out on your own. So grab your beverage of choice and use the search fxn here. 7. Case - Par-Metal 12x8x2. That'll work, but it'll be a tight fit. 8. Hook-up wire - how much (length wise) is need? Just get a bunch of it, you'll use more than you think and it's so cheap it doesn't make any sense to try and figure out the exact length you need. 9. Any other things I missed out? Hard telling, remember there's a reason kits aren't offered for most of these projects. Part of the idea is that you figure some of it out on your own. For the STEPS: 1. I've gotten pretty much everything figured out except the resistors. The recommended values are not listed so can you please let me know which values I need for R1, R2, R3, and R4. Concerning the R4 value, I don't know what the VOUT will be. Sorry Im really electronic illterate but Im just starting out in this hobby. Look at the schematic for the resistor values. For a Vout I think shooting for 25V would be a good starting point.. 2. I also dont know if i need 15VA or 25VA tranformer. Does it have anything to do with R4 value? For the amp you've described so far you'd be fine with either. It does not have anything to do with the R4 value really although the truth is more complex. 3. This is a stupid question but if i get a IEC inlet with a fuse holder in it, do also need a on-board fuse on the STEPS? Nope, one or the other is fine. However, there's no harm that I can see to having both.

One final suggestion, if this is your first project I'd recommend building something else first. While the physical construction of the M³ is not all that difficult if you do have a problem the troubleshooting can get rather complex. While the forums are here to help (and lord knows I've needed more than my fair share

) the M³ isn't intended as a frist project if you've never done anything like this before. I think it would time and money well spent to build something like a Cmoy or other small amp before attempting something like this.

Best of luck,

Nate

 

[JiggaD369]

hey Nate. Thanx alot buddy. I'm not that crazy to try and build this for my first project hehe. Most likely MisterX or someelse might be building it. As for spending the money, I'm considering spending about $300 in just parts so I just want the best sound I can get out of the $300. As for the caps, I've read that in PSU section, it really doesn't matter of which electrolyctics you use correct? If the gain for the M3 will be 5, what voltage do i have to set the STEPS output to? I'm really illetrate when it comes to electronics because I just got into this horrible hobby about couple months ago. I just want the best sound possible taking my parts expense limitation in concern. I just want the coreect parts ordered that way the I don't create a headache for the builder when they receive the parts.

 

[n_maher]

Quote:

Originally Posted by JiggaD369 hey Nate. Thanx alot buddy. I'm not that crazy to try and build this for my first project hehe. Most likely MisterX or someelse might be building it.

If this is the case I would highly suggest talking with that person about parts selection. Someone like Marshall is going to be able to provide you with plenty of advice concerning correct parts selection and quality vs. cost concerns. In my opinion it would be crazy to buy all of the parts and have them sent to the builder, most likely they would have 90% of what's needed already and would only have to place a small specific order to complete the process. This would save you $$ on shipping and probably save major hassle for the builder.

Regards,

Nate

 

[NeilR]

Even if you get an experienced builder to build it, if you think you will be poking around in the amp, you should absolutely get a fused IEC holder. Otherwise, it is possible to short out AC to ground/case in front of the fuse. Fused inlets are arguably safer.

 

[JiggaD369]

Nah. Im not a expert at this stuff so it wouldn't make sense for me to go and open up this thing and play around since I'll be dumping close to $500 on it.

Nate,

Would you know how much stock Marshall keeps? If he does keep most of it, it would save me bunch since I've only ordered once from Digi-key and it was only four or five parts for the M3. All the other parts I hope Marshall has them. I've already gotten the boards for the M3 and STEPS plus the Alps pento's. I'll be ordering the case and RCA jacks next week. So mostly I'm just in need for caps and internal parts. Hopefully Marshall has all the caps, resistors, adaptors, etc.
Do I need to use a rotary switch or a DPDT switch for the selector between the 2 inputs? Also, does a high quality switch effect the sound?

 

[Teerawit]

Quote:

Originally Posted by JiggaD369 All the other parts I hope Marshall has them. I've already gotten the boards for the M3 and STEPS plus the Alps pento's. I'll be ordering the case and RCA jacks next week. So mostly I'm just in need for caps and internal parts. Hopefully Marshall has all the caps, resistors, adaptors, etc.

Why don't you order them to be shipped to MisterX's address? It just seems more economical.

Quote:

Do I need to use a rotary switch or a DPDT switch for the selector between the 2 inputs?

Either/or. A rotary switch is fine if you like rotating a switch to select your input or add more inputs later etc. Otherwise I would say a 3PDT switch for two inputs (left, right, ground on the poles).

 

[JiggaD369]

I thought they only ship to address thats on your credit card?

Would different switches have different sound or it doesnt matter what type of switch it is?

 

[NeilR]

Quote:

Originally Posted by Teerawit Why don't you order them to be shipped to MisterX's address? It just seems more economical. Either/or. A rotary switch is fine if you like rotating a switch to select your input or add more inputs later etc. Otherwise I would say a 3PDT switch for two inputs (left, right, ground on the poles).

Teerawit,

Why not just use a DPDT, especially since in many configurations the input ground goes to the case anyway.... are concerned about "mixing grounds" ?

 

[Teerawit]

Quote:

Originally Posted by NeilR Teerawit, Why not just use a DPDT, especially since in many configurations the input ground goes to the case anyway.... are concerned about "mixing grounds" ?

Yeah that's my concern...I feel it is more "proper"

and a 3PDT switch doesn't cost much more.

 

[NeilR]

Teerawit.... OK... I look at my Home Theater receiver with 5,000 interconnects linking the world together (well that's how it felt after spending so many hours on my back fishing wires). I figure if mixing grounds was a problem all I would hear is hum

I see your point, though, from a purist sense. We probably obsess about less important things.

 

[n_maher]

Quote:

Originally Posted by JiggaD369 Nate, Would you know how much stock Marshall keeps?

No idea, but I'm guessing a PM will solve the mystery for you. If he's anything like me he's got a stash of parts that he's embarrased to talk about - probably even more than me since he's prone to building a lot of these things. And not that I'm out to try tell you not to have Marshall build the amp for you but have you talked to Stephen at Rockhopper Audio? He's another great M³ resource and a very capable builder.

Best of luck with the amp, the M³ has been a great sounding piece of gear in every setup I've heard it in. I just couldn't afford to keep mine

.

Nate