*** The DIY Audio Thread ***
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Associate
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Founder film;
Nice looking amp! The 1875 is a nice little chip, I built an amp with the TDA2030AV which is similar and it gave impressive results.
You may be finding less bass impact through using relatively small capacitors, yours look like 4700uf tops? Also good grounding and low resistance power connections will help. I have built all my recent power supply boards with copper clad boards. The simple layout needed can be scored with a knife and the breaks created by pulling the track up with tweezers, its easy with the right tools and technique.
Heres some pictures of a standard capacitor board made this way, the bridge on there is actually part of a mains loop breaker and is not the rectifier; the small PCB is a speaker protection board mounted there for convenience
Do you yet have your chassis grounded? You should do this if you haven't and ideally connect circuit ground to earth too but this can cause problems with earth loops (hence the use of the breaker on mine, if you using your amp with portable mp3 players or most CD players you shouldn't need a breaker, using with a desktop PC you would do).
The caps on my rectifier boards are only 1000uF so yes that is probably limiting the bass. Might be a future upgrade
|I do indeed have my chassis grounded. A safety earth ground from my mains connector to the chassis, then a separate star ground point (also connected to the chassis) that connects the ground track on the PCB, ground connection out of the rectifier boards and a direct connection from the speaker grounds on the PCB. I might add a breaker at some point too.
1000uf would be about the bare minimum, do you find there's any humming from the speakers? That board I posted is 15,000uf per rail and is only for midrange but with my TDA2030 amp I used only 4700uf per rail.
Sounds like your grounding is all correct. Don't add in a breaker unless you experience ground loops, a direct connection is the safest (I had to use breakers as i'm running 3 amps and if they all had direct grounds there would be a lot of hum!). Make sure that safety ground connection is secure and direct to the transformer; it should be mechanical and not soldered as the solder can melt carrying a fault current but as you can see I soldered mine (there is a reason I could do it in this case).
Sounds like your grounding is all correct. Don't add in a breaker unless you experience ground loops, a direct connection is the safest (I had to use breakers as i'm running 3 amps and if they all had direct grounds there would be a lot of hum!). Make sure that safety ground connection is secure and direct to the transformer; it should be mechanical and not soldered as the solder can melt carrying a fault current but as you can see I soldered mine (there is a reason I could do it in this case).
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I think I will increase the size of the powersupply caps but as you can see from my rectifier boards there is a space issue. I will try and go for 4700uF if they will fit ok. As for humming, I think there is a slight hum yes but I need to check, it is very faint though.
Yes my groundings are mechanical and not soldered. Attached to an area of the chassis with the paint removed and using "toothed" washers.
4700uf should fit, they are just taller really. I actually have a pic of my power supply for the TDA2030 amp, wouldn't reccomend the stripboard here unless you add solder over the back but its easier to do a clap board layout really. This board had no reinforcement of the tracks so it would be max 5A or so for typical stripboard, sounds reasonable but could be a problem when first switched on. My poor grounding unfortunately broke this amp, twice, lesson learned 
. Was fine in normal use, ironically some testing destroyed it, use of grounded scope with grounded amp can cause problems.
. Was fine in normal use, ironically some testing destroyed it, use of grounded scope with grounded amp can cause problems.
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Great work looking good. Impressed you went for a tube project straight away.
Here is my completed LM1875 gainclone. Just got the speakers today
. A pair of Cambridge Audio S30's, got them for £100 which was a £20 saving on the list price.
Anyway they it all sounds great!!
The amp is in the middle. My Pioneer 5.1 amp is not getting used anymore. But just kept it in the stand as it matches my DVD player.
Here is my completed LM1875 gainclone. Just got the speakers today
. A pair of Cambridge Audio S30's, got them for £100 which was a £20 saving on the list price.Anyway they it all sounds great!!
The amp is in the middle. My Pioneer 5.1 amp is not getting used anymore. But just kept it in the stand as it matches my DVD player.
Soldato
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Soldato
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Nice amp Justin, good to see some more tubes on the block.
Yep, I think it's just a case of the DCX2496 giving out too much voltage... I'm giong to look into building a passive pre-amp with shunt resistors, this is apparently the way forward.The DCX2496 may run at professional +4dbu level rather than the typical home equiptment level of -10dbu. Can't remember what these are voltage wise but its quite a difference and would explain the need for attenuation
I have tried turning the output gains right down, but as you said I lose resolution... I'll keep them up for now (I also have some 24/96 material) and just be careful when tweaking the volume...
cheap DAC, all the way from Hong Kong.
Black PCBs all round. \o/
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ive got this kit well apart from the blue tranformer thing, mine is metal. anyways ive been reading around from what my feeble mind can make out a little bit of modding will give me better sound ive not got a large budget. so what would you recomend?
ill be mainly using it for gaming hooked up to ps3/360/pc with my grado headphones and cmoy amp
i will prolly undertake a better diy headphone amp than the cmpy in a month or so
http://www.diyaudio.com/
only problem is its not newbie frindly. any thread you start turns into the thread of knowledge
ie old pros will spank out diagrams names of chips,transsistors etc. its has tons of info and sopme top top draw projects on.
http://diyaudioprojects.com
only problem is its not newbie frindly. any thread you start turns into the thread of knowledge
ie old pros will spank out diagrams names of chips,transsistors etc. its has tons of info and sopme top top draw projects on.
http://diyaudioprojects.com
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I've got a few links, which I'll post up later on. They're somewhere in this thread, if you can be bothered to search through.
i would like to get into all this home-made diy malarky. Where can i find details on how to build them? Thanks
Have a read over at head-fi, this thread has lots of links. Can you read a schematic? Maybe a good book to read up on (Adam W has good recommendations iirc) or catch me on MSN, pretty sure I have you added?