Any advice for parts to use in a Hairball 1176 Rev A?

[Deadly Mix]

Will do. Thanks, guys. I finally got a text from Cory lastnight after posting. He has Covid so he won't be helping with this build. You have no idea how much I appreciate the help.
I think I definitely need to invest in a better multimeter. This thing doesn't even beep when I test circuits. I have to watch the screen. Ff numbers start moving, the circuit works. Otherwise this thing is just barely better than nothing. Definitely gonna need a better one to find any precise numeric values.
Also gonna need a better way to clean the iron tip too.
About to pull out the main PCB and get back to building so I'll probably be on here off and on for the rest of the night lol.

 

[HerbertR]

I also built the last weeks a pair of Mnats Rev A and D, and one pair of Gyrafs Ref G.
My first 1176 builds l were a pair Gyraf Rev F that I built a few months ago. All are suuuuperr great. Input-transformerless Ref G is the most versatile for me - more precise than all other ones, a little bit more "Hifi", bit A is more "analog" and little but less "punchy" with more saturation color. A matter of taste.... As for the Transformers for A and D I ve used Cinemags. Long waiting time - actually three months. But with an excellent price - compared the more expensive, but good available Lundahls. For A and D you also need an expensive T-Pad. So Gyraf F and Mnats A and D have at end nearly the same price. I could build every piece for about 500 Euros and I have used good components like BD517 and 518, 2N3707, NOS Philips BF245As...
Btw for the 500' Lovers I can recommend Igors F76 500 with his cool Opamp Variations, also for 51x... PCBs...are available from Franks frontpanel.de...

 

[Deadly Mix]

View attachment 85463I also built the last weeks a pair of Mnats Rev A and D, and one pair of Gyrafs Ref G.
My first 1176 builds l were a pair Gyraf Rev F that I built a few months ago. All are suuuuperr great. Input-transformerless Ref G is the most versatile for me - more precise than all other ones, a little bit more "Hifi", bit A is more "analog" and little but less "punchy" with more saturation color. A matter of taste.... As for the Transformers for A and D I ve used Cinemags. Long waiting time - actually three months. But with an excellent price - compared the more expensive, but good available Lundahls. For A and D you also need an expensive T-Pad. So Gyraf F and Mnats A and D have at end nearly the same price. I could build every piece for about 500 Euros and I have used good components like BD517 and 518, 2N3707, NOS Philips BF245As...
Btw for the 500' Lovers I can recommend Igors F76 500 with his cool Opamp Variations, also for 51x... PCBs...are available from Franks frontpanel.de...

Thanks. I'll keep that in mind. You clearly have had opportunity to compare lol

 

[Deadly Mix]

2 big questions:
1) Is this R81 and R82 in this bag (pic 1)? I'm looking for the small resistors that go in between the top and bottom row of fat ones in the image shown on Hairballs instructions (pic 2).

The stripes all look black on Hairball's picture but I don't see R81 nor R82 listed on the Rev A Components sheet and this bag fell out, presumably when I opened the power supply box and I found it on the ground.

2) If they are the right ones, is there a particular way they need to go in? 2 red stripes pointing toward the CR8 for both resistors? 1 red stripe side to the CR8 side? One goes one way the other goes another? Does it not matter?

Resistor direction didn't seem to matter while customizing my cousin's blinkers on his bike. Does that matter here?

 

[Deadly Mix]

Nevermind that last question. I found a good picture of a finished unit. That's them and the side with 2 red stripes went toward the power transformer side.

Now my issue is going any further without a DMM that doesn't suck lol.

This cheap one has to be manually set and I don't know what to make of it.

I'm at the stage where I'm checking the power. I don't know what to make of this. Is the DMM set right but I only have 1/100th of the voltage I should? Am I doing something wrong altogether?

I'm gonna shell out for a good DMM but, in the meantime this is what I have to work with.

 

[Deadly Mix]

Here's the image I forgot to attach

 

[Deadly Mix]

If I set the DMM to DCV 20 and move the decimal right 1 space, everything is within 5% of being right?
Logically, since I tried both the CR8 and CR9 checks on DCV at "20" and they both turned out to be within 5% once I move the decimal right 1 space; that seems like the way to go. I just don't want to make the assumption and move forward until someone confirms.

The DMM I'm using can be seen in the picture above.

 

[Deadly Mix]

I sent pictures of reading to Cory and apparently it's all on track.
So I installed the remaining diodes.
I also know what the colors mean now so I think installing resistors is gonna be easy now.
I just have to pay close attention and go by the number on the sheet of paper in the box.

 

[Deadly Mix]

Okay, nope.
Now I'm confused again.
R17 says it should be 4.7k (4,7,0,1, then resistance stripe)
That would be yellow, purple, black, brown...

The picture appears to be:
green, blue, black, black (560).

What's going on?

 

[JMan]

Trust the BOM/overlay/schematic and just make sure your resistor code is the right value. Pictures, even when nice and clear, can egregiously misrepresent those little color bands.

 

[Deadly Mix]

I got past all that but this one I really do need help on.
Which is 100% correct? The picture or the Rev A Components paper?

R15 appears to be one of the tan colored resistors but the paper says its only 20K

I have the Red, black, Black, Red, brown resistor in my hand... but its blue.

The only way it could be tan is if a 0 or two was left off on the value and that can't be because I dont have a tan one that even starts with a 2.

 

[Deadly Mix]

Trust the BOM/overlay/schematic and just make sure your resistor code is the right value. Pictures, even when nice and clear, can egregiously misrepresent those little color bands.

So use the 20k Red, black, Black, Red, brown - blue resistor for R15?

 

[JMan]

So use the 20k Red, black, Black, Red, brown - blue resistor for R15?

That sounds like a 20k resistor to me, so if that’s what is called for, then yes.

The tan resistors probably have a four-band color code, a higher tolerance, and probably are some of your more high-value resistors. But otherwise they are no different from the blue ones. Just make sure you’re confirming the values using the color codes and you’ll be fine.

 

[Deadly Mix]

Okay. That's very useful information because R6, R7, and R10 are also tan in the picture but no tan resistor begins with 2 red stripes then a green. Just 3 blue resistors with red, red, black, yellow.
I suppose what has been throwing me off is not knowing a resistor could come in both a tan version and blue.

"Just trust the BOM" seems solid enough advice to overcome that uncertainty. Thank you.

 

[beatnik]

In my experience, my REV A has a lot of colour. Sounds absolutely amazing, but it can be a little too much depending on what you're going for. The noise floor can be a little too high for delicate tracks. There is the orange drop mod where you make a REV D which has a noticeably lower noise floor, and swap in the orange caps from the REV A to get the distortion of the REV A with the lower noise floor of the REV D. Not sure what the final product sounds like but is worth looking into if this is what you want.

https://www.hairballaudio.com/catalog/fet-rack/fetrack-orange-drop-mod
Hope this helps you on your journey in some way.

Changing the film capacitors to orange drops is unlikely going to affect distortion and noise floor, sounds like audiophoolery thinking to me, and a way for hairball to profit from this kind of misinformation.

Also this capacitor change doesn't make a rev A become a rev D. The two revision have a different input preamp stage, that's why each unit comes with a different main board pcb

On the other end it is important to adjust the distortion trimpot with a proper thd meter or some kind of plugin. This adjustment is not always mentioned in diy discussions and mnats didn't make a video for it, but it is nevertheless a very important adjustment

 

[Deadly Mix]

I fucked up. I went hard last night finding all the pieces and installing them on the PCB. Then today I soldered it all in.
Only then did I relize I forgot to put the spacer beneath the 2N3053.

I'm ordering a vintage one that was spare parts for an original 1176. Will this part have any affect on the sound?
I`m ordering it because, unlike a company, I can quickly reach the seller and discuss overnighting it but it would be nice to learn it actually has some benefit over ordering new from Mouser.

 

[Deadly Mix]

...if I can ever get the damn thing off .
This one is so much more of a pain than the types I've replaced in the past.

 

[Deadly Mix]

Hey, wait a minute. While looking for an original input transformer, I ran across the Cinemag that looks like it's what would go in this board. The problem is that I've never seen that before and I've been in my box over 200 times now.

I have the transformer I hooked up when I built the power supply and I have one that looks like that still in my box but I have not seen a cylindrical transformer with 2 rows of 4 pins.
I ordered the complete kit + stereo link.
Shouldn't I have one of those in my box?

 

[JMan]

You’re sure there is no input transformer included in your box? If that’s the case, you should contact Hairball for a replacement, but I’d do a very thorough check first. Look around your build area too, make sure you didn’t set the little box aside at an earlier stage and didn’t notice. I do that all the time lol

 

[Deadly Mix]

You’re sure there is no input transformer included in your box? If that’s the case, you should contact Hairball for a replacement, but I’d do a very thorough check first. Look around your build area too, make sure you didn’t set the little box aside at an earlier stage and didn’t notice. I do that all the time lol

Nevermind. It's just smaller than it looks in pictures. It was underneath the output transformer when I opened the transformers box from the other end.

If I can track down the original input transformer that was in the Urei, anyone know how I would get it to work in this board? The pictures I've seen appear to have the leads arranged in a circular pattern. Is there a coupling device that can bridge the two, maybe bridge each lead with wire, or some other configuration? Or would doing so make it actually sound less like the original because other values were changed to compensate some differences?