* The DIY Audio Thread *

Dr.EM · 19 Sep 2008 at 11:53

I had considered it but was mainly worried about burning things. Seems wierd soldering indoors to me, always work in the garage with it. Remember soldering something for a freind on his bed once! Was ok luckily.

ChrissyT88 · 19 Sep 2008 at 12:31

I must admit i was considering taking an iron etc, but i thought twice and i think it would be best not to. What with the sudden injection of cash the loan brings and (to be honest), quite a lot of time where i dont 'have' to do any work, i can see no work getting done at all. There are too many distractions already (im looking at you, shared xbox!), and i really need to do more work this year....

Mr. Brightside · 20 Sep 2008 at 18:07

I'm thinking of getting some Mordaunt Short 902is replace my current system with, and to take to uni. However amp wise I want to build my own and have been looking at the 41Hz kits.

Just wondering which 41Hz amp is the best to pair with the speakers I'm going to get, in terms of matching power outputs. I'm thinking either the AMP10 or AMP10-BASIC.

I see the AMP10 has larger bulk capacitors - if I understand correctly, this improves transient response? But the AMP10-BASIC has an output relay which I'm assuming is a good thing as it offers the speakers some protection?

Which is the better choice and why?

Thanks.

adamau5 · 20 Sep 2008 at 18:24

eat my valves

p4radox · 20 Sep 2008 at 18:50

Mr Brightside - I'd definitely go with the AMP10 basic over the AMP10. But do make sure you scan the forums on 41Hz before building it up. It looks like there are a few errors in the schematic/BOM that people have worked out.

Adam - that looks amazing. I've got a few questions:

What do the two knobs do?
What sort of transformer is that? Encapsulated?
Are you using the case as a "ground" for the input/output signals, or have you isolated the RCA connectors from the case somehow?

adamau5 · 20 Sep 2008 at 19:02

left knob is the negative feedback control. Second knob is volume

transformer is an R-core, useful because it has so many secondaries.

the grounds all go to star ground, which is in connected to the chassis. the rcas are isolated, the red / white washers isolate it. too 6 solid hours to build!

p4radox · 20 Sep 2008 at 19:05

I've got the same case (but slightly shallower) and was planning on EARTHing the case, but having just put the RCAs connectors on this afternoon the outer part shorts with the case. This isn't what I wanted so I wrapped the shaft in one layer of electrical tape.

Are you sure yours don't short on the inside of the drilled hole?

adamau5 · 20 Sep 2008 at 19:12

yep, there is a step on the washers, fits snug in the hole (I used a stepped drill bit.

p4radox · 20 Sep 2008 at 19:13

Ah cool. There was a step on one of my washers too, for some reason I didn't twig that was what it was for...

Mr. Brightside · 20 Sep 2008 at 19:26

p4radox said:
Mr Brightside - I'd definitely go with the AMP10 basic over the AMP10. But do make sure you scan the forums on 41Hz before building it up. It looks like there are a few errors in the schematic/BOM that people have worked out.

Thanks. Is it better due to having the output relay? Or are there further differences other than the relay?

p4radox · 20 Sep 2008 at 19:31

The relay is the main thing. You also don't have to wind your own toroidal inductors (which is fun, but takes a long time to get right).

edit: shouldn't you be building that robot?

ChrissyT88 · 20 Sep 2008 at 19:48

Adam - just saw your bijou on head-fi before looking on here. It looks really good. Did you buy the kits from glassjar audio or did you buy all the bits yourself separately? How does it sound (im guessing good!)?

adamau5 · 20 Sep 2008 at 19:53

bought the kit from glass jar, but i have some bits that are going in (e.g obbligato caps, and i will go for a stepped attenuator).

The sound is phenominal, unreal space. Its created a massive soundstage that i just havent heard before.

I have a minor issue with usb noise (alien Dac), so i imagine i have a grounding issue to fine, shouldnt be a problem thought. Just enjoying listening now.

It also works well as a heater.....

ChrissyT88 · 20 Sep 2008 at 20:23

Well, at least it sounds better than the radiator! Some of the headphone amps look really good fun to build, but i dont really have any decent headphones... Maybe one day!

adamau5 · 20 Sep 2008 at 20:33

I just picked up some beyerdynamic dt990's for £50. very decent headphones, some music i prefer them to my senn 650's.

Mr. Brightside · 20 Sep 2008 at 20:49

p4radox said:
The relay is the main thing. You also don't have to wind your own toroidal inductors (which is fun, but takes a long time to get right).

edit: shouldn't you be building that robot?

Thanks again. Looks like I'll be getting the AMP10-BASIC then. So the only drawback of the BASIC is the smaller bulk capacitors (which I'm guessing only matters at higher powers)?

Ignoring cost for a moment, would it be a bad idea to buy two AMP10-BASICs and use them bridged, one for each speaker? Just that I see the speakers are rated at 100W yet when used as a stereo amp the AMP10 is 50WPC. I realise I'll rarely need this much power, so this question is mainly hypothetical.

The robot is on hold now, as two of the team of four have already gone to University/Year in Industry, and the other goes pretty soon. I might do a bit more chassis work and some electronics development though before I go.

I'm guessing you're going back for your second year at Cambridge then? What college are you at?

p4radox · 20 Sep 2008 at 23:05

Mr. Brightside said:
Thanks again. Looks like I'll be getting the AMP10-BASIC then. So the only drawback of the BASIC is the smaller bulk capacitors (which I'm guessing only matters at higher powers)?

Ignoring cost for a moment, would it be a bad idea to buy two AMP10-BASICs and use them bridged, one for each speaker? Just that I see the speakers are rated at 100W yet when used as a stereo amp the AMP10 is 50WPC. I realise I'll rarely need this much power, so this question is mainly hypothetical.

The robot is on hold now, as two of the team of four have already gone to University/Year in Industry, and the other goes pretty soon. I might do a bit more chassis work and some electronics development though before I go.

I'm guessing you're going back for your second year at Cambridge then? What college are you at?

I don't know enough about bridging to be of any use, unfortunately.

Yup, I'm back at Selwyn next weekend. Desperate to get this finished first, but I've got a week after I arrive before freshers' week starts, so perhaps a bit of tinkering might be in order.

adamau5 · 21 Sep 2008 at 08:58

the bijou is jaw dropping. I cant analyse it because you just end up listening to the music. serious eye opener.

by the way, there is a thread on head-fi for a uk meet, hopefully in oxford in the near future. Geeky, btu maybe fun.

ChrissyT88 · 21 Sep 2008 at 13:10

Completely off topic, but my application to cambridge was pooled and i was asked to interview again at Selwyn - i didnt get in, but one of my friends did.

The bijou looks awesome - glad to hear it sounds good. Any plans to try the SOHA II Adam? Im not a member at head-fi, but some of the DIY threads make for a good read, although i wouldnt consider myself a headphone aficionado - more of a speaker person!

MikeHunt79 · 21 Sep 2008 at 13:39

Mr Brightside: Check out the amp9 basic, by the looks of it your speakers are bi-ampable and the amp9 basic is perfect for this.

*** The DIY Audio Thread ***

* The DIY Audio Thread *