*** The DIY Audio Thread ***

Hi, ive been inspired by this thread but i am a complete noob (soldered for the first time today:). Ive got an amp 9b from 41hz.

Am i right in thinking i can put capacitors and resistors in either way?

How do i know which way to attach diodes?

Can anyone send me a high def photo of their amp9 top but in particular the bottom? (use hotmail email in trust)

Any help much appreciated.
 
You can put resistors in either way.

Diodes only work in one direction. Usually there's a white line on one end which corresponds to the "negative" terminal.

Some capacitors have a polarity - electrolytics for example. The negative side is marked on the package with "-" signs and the negative leg is usually the shorter one. On the PCB the square hole is positive.

There should be some pictures on the 41Hz site of an assembled Amp9 PCB. Check the support section.
 
Try the forum, you might find that someone has posted an image.

I think Mikehunt79 has an AMP9b, try getting hold of him.
 
Working on a Millet Starving Student headphone amp...finally found some time to work on it and got most of my soldering done today. Just need to finish a few things before I go buy a chassis. A bit messy but I think it will be ok once I get it all organized into a chassis.

This is only my 2nd project (1st was just a desktop cmoy).


img3654lq7.jpg
 
I want to give one of those a go - looks like a good introduction to tube amps (plus the cost is low!). Really must sort out something to build soon - im getting envious looking at threads on diyaudio and head-fi!
 
Yeah it seems like a very good intro to tubes. I bought this one as a kit but I may piece together my own and do another one down the line. I'm sure I will learn a few thigns doing this one and I can improve on them :)
 
I am going to order the parts I need for my powersupply circuit sometime next week and I just want to make sure I am getting the right stuff. Here is what I am to order:

Traffo:
Toroidal transformer,160VA, single 230V primary, 2x18V

Bridges:
8 X Rectifier diode,MUR860 8A 600V
Pack of 5 - Panasonic FC radial elec cap,1500uF 50V

Below is a diagram of the supply I want to make (the Panasonic smoothing caps aren't shown on the diagram):

2964201392_a26ffa2d8d_o.jpg


So basically is this circuit all correct? I went with the single primary, dual secondary into two separate rectifiers approach because it was the easiest to get my head around :p
 
gurusan said:
Yeah it seems like a very good intro to tubes. I bought this one as a kit but I may piece together my own and do another one down the line. I'm sure I will learn a few thigns doing this one and I can improve on them :)
Click to expand...
Hey gurusan,

Do you know how these Millet Starving Student amps perform compared to budget amp like the Head Box 2's and equivalent?

Very interested.

Just bought a Beresford 7510 to go with my Head Box II and have been really impressed but from the sound of it i think that my 650's could be improved by moving to tube amplification. Would the Millet drive it ok?

gt
 
Dr.EM said:
Looks about right Founder_film, probably worth reading this article too though:

http://sound.westhost.com/project04.htm

:)
Click to expand...

Thanks for that but I am a bit confused again.

The design shown in the link is for a centre tapped tranformer right?

So for my circuit, using dual secondaries, do I need to connect my mains earth to the signal earth which comes from the secondaries and goes into the amp PCBs?
 
Millet student amp looks ace, I built its big brother the hybrid MAX, and spent about 150-200 on it by the time I totted up all the costs. But no expense was spared for Blackgates, POT and N.O.S caps. SOunds lovely with grados though.
 
gurusan, how are you going to case that up without desoldering?

with valves the first step is casework, then solder, and get the wiring right in situ. A cracking book is "building Valves amplifiers" by morgan jones. Would thouroughly advise it.
 
Ok I have expanded on my power supply circuit diagram, I have added the smoothing caps (gone for 4700uF instead) and modified the grounding:

2964991314_0796ca6b74_b.jpg


I did a bit more looking around and turns out I do have to connect the signal and mains grounds together. Therefore is this the correct way to connect up all of the grounds?
 
I wonder if I could get some advice from you DIY hifi gurus.

I've got this old Phillips CD618 in the loft that I was thinking about getting a DAC for and then I happened upon an old thread somewhere, where someone had modded their one with some good results. That got me thinking and then I remembered this thread and figured it was the best place to ask.

So.......Where can I find the info/parts to put together an external DAC or to mod the internals, can I do it relatively cheap and will it worth doing ie, will it sound much better?

I'm reasonably well skilled with a soldering iron and although I don't have a huge amount of electronics knowledge myself, we have an electronics dept at work that I can go to for help and equipment should I get stuck at all with the assembly etc.

I like a challenge and this sort of thing fascinates me so what do you think, should I go for it?
 
gt_junkie said:
Hey gurusan,

Do you know how these Millet Starving Student amps perform compared to budget amp like the Head Box 2's and equivalent?

Very interested.

Just bought a Beresford 7510 to go with my Head Box II and have been really impressed but from the sound of it i think that my 650's could be improved by moving to tube amplification. Would the Millet drive it ok?

gt
Click to expand...

The starving student is supposed to sound pretty good, I'm not entirely sure how it compares with the headbox though...I'm fairly new at this and have only heard my HD 580s through a CMOY. I will let you know my impressions once it's complete though...and I'll probably try building another one afterwards before moving on to something else.

Adam W said:
gurusan, how are you going to case that up without desoldering?

with valves the first step is casework, then solder, and get the wiring right in situ. A cracking book is "building Valves amplifiers" by morgan jones. Would thouroughly advise it.
Click to expand...

I was confused on how the little retaining brackets secure the socket to the case. Also was a bit hungover while making it :/ I will figure it out this weekend with a clear head. thanks for the advice on the book, I will check it out.


***edit*** just found this...looks like I will be doing some desoldering lol

59000974ay0.png
 
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gurusan said:
The starving student is supposed to sound pretty good, I'm not entirely sure how it compares with the headbox though...I'm fairly new at this and have only heard my HD 580s through a CMOY. I will let you know my impressions once it's complete though...and I'll probably try building another one afterwards before moving on to something else.
Click to expand...
Excellent - thanks gurusan!

gt
 
I built a starving student (its in this thread somewhere...edit, found it)

img9249wo6.jpg


sound - very valvey (sweet mid range), great with grados (really great), not quite enough ooomph with senns (particularly the 650's).
 
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Adam W said:
I built a starving student (its in this thread somewhere...edit, found it)

sound - very valvey (sweet mid range), great with grados (really great), not quite enough ooomph with senns (particularly the 650's).
Click to expand...
Thanks Adam,

Good to know - which type of valve amps would you recommend that could drive the 650's properly?

gt
 
Hey everyone. Working on my starving student millet hybrid amp..... This is my 2nd project (1st was cmoy) and I'm having some problems.

I wired up 1 channel and the tube is glowing, the mosfet is warm, but I am not getting any sound.

I accidentally wired the mosfets in wrong the first time, could they be blown? How can I test this?

Also when I wired the mosfet in wrong, the tube glowed like a nuclear reactor and now the plates of that tube are darker than the other tube......
*************

on another note my DAC seems to have blown up :/ The transformer got very very hot suddenly with no warning, and started melting through my case.

I wonder if the rest of the DAC is ok, but i somehow doubt it :(
 
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