bpribadi

Looks better on the IG and OG But I hope you give up using OPA2134 for the ground channel It's kind of defeating the purpose of using A47 for the Right and Left Channel. Look, with A47 on the Left and Right Channel, in theory each can supply 80 mA current if using OPA2134 (60mA with OPA2228). So an ideal ground should be able to cater for 160 mA. But with the circuit above, max only 80 mA. And also connecting 2 output without any resistor is just not right (as you said might cause oscillation). In most cases, only 1 op-amp will work at a time. So my suggestion is, don't use the A47 circuit for the ground channel, and use a simple unity gain single op-amp config with high current output op-amp such as LM6171 (the cheapest option, 135 mA), or OPA551 for higher output current (200 mA), but OPA551 cost around SGD 7 - 8 each (Will be cheaper if you buy in bulk). My 2 Cents

Very neat layout Don't mind sharing the schematic?

Yeah, looks neater How do you use the OPA2134 for the ground channel without any resistor? Using single channel or dual? Did you put the input signal ground after the output of the ground channel, or still at the input? Let's compare the sounds of the 3 variants

So if we want to have a small meeting to compare our A47 amps, we can meet around SLS on Saturday at 10 am

That's what I did in my Pimeta clone and my brother amp But for Jason amp, I think the mod will be too much. I try to follow Jason goal which is to make budget amp, so I didn't use expensive components. I use only Op-Amp which are not so much more expensive than the OPA2134 to upgrade / mod the amp. Jason when shall we meet? Tropical, what time you start working in the morning? Maybe Saturday morning is good before you start working. Jason, I can pass the amp to you for testing and carefull listening at home, so you can finalized your circuit

Wow, that's cool Tropical, do you mean the bass is better with the modded ground? Or it might be because of the expensive OPA627? What I understand, the A47 circuit is not good for ground, since it introduce resistor in the ground channel. We know that ground should stay at 0 volt all the time, and ground also should be able to handle large current flow. So if there is resistor in the ground channel, and large current flow going through it... It is hard to keep the ground voltage to 0 volt ( I x R = V). That's the reason I change the ground channel to the simple unity gain op-amp config. The LM6171 is just perfect for Jason Amp, since the goal is budget amp, and LM6171 price is less than S$ 1 more expensive than the OPA2134. The OPA2228 introduce louder 'crack' sound when the headphone is pluged, and I turn the amp On>Off or the other way Off>On . With OPA2134 the 'crack' sound is soft, not as scary as the OPA2228. So with OPA2228, I have to unplug the headphone before toggle the power. I haven't check the DC offset. Haven't tried with AD8620.

Yes, I agree, this is a super thread Hopefully Jason can meet his target, last time he said to finalized this amp by Christmas, this year, not next year Yesterday I bought another OPA2228 from Farnell (previously I only have one piece) to try it in the modified Jason A47. Just rolled the OPA2134 with OPA2228, it sounds much better to my ears For me, somehow the OPA2228 sounds much more musical than the OPA2134. I'm sorry Jason, I know you have bought 100 pcs of OPA2134 from Farnell But I must be honest, I favor OPA2228 more than the OPA2134, so I think it is a significant upgrade to your amp

Check this on Farnell Website: 152063, 1/4" panel socket, looks like your Rean socket from Cliff. 212179, the Neutrik line socket. 211424, the XLR 3 pole Free Socket. 148261, alternative for the 1/4" jack.

Are you sure there is no resistor in paralel with C1? Wait for you to make 2 channels, so you can tell us how it sounds That's the most important thing rite

Which shop? Thanks!

Hepi Bedey !!!

ALPS RK9 from Farnell. Check page 11 for more information.

I made one using Daiyo Mini to RCA (2m), I cut, took the mini jack, and put another RCAs, to make them short (50 cm) mini to RCA.

I bought a S$ 5.- mini jack to mini socket extension, 5 m long. Sometime I need it to listen to TV. But after a while, the jack spoilt Well, cheapo cable, what to expect So I decided to make one myself using the cheap and good PC-OFC S-VHS cable. It is S$ 2.- per meter, 5 mm in diameter. Inside the cable are two individual coaxial cables, so fully shielded. I made it 4 meters long, with mini jack and socket, total cost less than S$ 12.-. How it sounds? Before comparing, I was ready to hear some slight degradation of sound, considering the price of the cable, and the length. I also have the one from Grado RS-1, extension for the 6.25 mm headphone jack, about the same length. So I compared the sound with the Grado extension, my DIY extesion, and without extension at all. I use The Chesky Ultimate Demonstration Disc, track 15 and 17. Track 15 is Saxophone track with incredible detail of the mechanical sound of the saxophone, and also high transient of sax sound. Track 17 is impact-dynamic test. I also use some other song to test the vocal sound. The result: I'm a bit dissapointed with my ears, because I hardly hear the difference Is it my ears that became less sensitive, or the cables are so good ? I can tell you, in general, no audible difference, with and without the extension. Both the Grado extension (I heard it is unshielded, so might be prone to RFI & EMI intereference) and my DIY extension (fully shielded) sound good. Almost no audible sound degradation at all. So I listened more carefully, comparing the extensions, and without extension. Really hard to hear the difference, not like when I was comparing Op-Amp, the sound difference is easier to notice. I would say, if there is audible difference, but it is subjective, the result either from my hearing or my imagination, the extension might reduce the dynamic and transparancy a little bit... so little, I almost couldn't hear the difference. So, I'm happy with my cheap and good 4 meters DIY extension

Hi Naz, looks like the finish of the wood of my RS-1 a bit different different than yours. The color looks a bit lighter than yours But the centre wood looks the same, they are actually the same color with the tube.

Selamat Hari Raya Aidil Fitri to all muslim members !!!

Good to know we have another DIY guru Please join us in the DIY forum

There are some (a lot) good BB and AD chips specified for +/- 5 volts, they might be enough for 32 ohm headphone, but not high enough for 600 ohm headphone

How about the main component, the Op-Amp? OPA637 > Farnell ~ SGD 37.5 (after GST), don't know how much in Federal. AD8610, don't know where to get in Singapore, but I prefer the AD8065 over the AD8610. Neutrik Locking Socket > Hung Brothers & LHS ~ SGD 7.5 not glod plated, ~ SGD 11 gold plated.

Well done Tropical! How's the MAX sounds? No studio lighting, just bounce the flash to the ceiling

How long are those cables? The professional cable sounds like they are microphone cables.

Have any of you listen to the new FX6021 ? I heard from a few friends, it sounds good for music. It is more expensive than the MX5021. To my point of view, combination of 1 inch fullrange and a subwoofer will have gap in the midrange. But who knows, it might sounds good. So far from my observation, the 2" fullrange normally will sound more musical than the 1" one. http://www.altecmm.com/product_quote_intl....country_code=sg

Looking at the spec on the Altec website might give us impression that this MX5021 is good for music. I was interested with it before. But listening to it made me steped back . I listened in a few shop in Sim Lim, I know they don't connect it to a good source, and SLS is relatively noisy, so it is not objective at all. My impression is, it has powerfull bass (specific Altec), but not boomy (at least for the price and class). What I don't like is the midrange and treble which for me are not musical. Tends towards those syntheziser sound, not natural. I have the cheap AL 221, even though there is no way this little 2.1 to sound high end, but to me it sounds musical. Means, I can listen music, and I enjoy it. It sounds very laid back, with far from perfect treble and mid, but somehow I can enjoy listening music with it while working with the PC. In the same place (Video Pro), I also listen to Yamaha YST-MS50 (SGD 99), which looks like old PC speaker, doesn't look as cool as the MX5021, but to me the Yamaha sounds more musical. Well, just FYI, we might have different taste, just try them yourself

Very cool interconnects!!! Well done Tropical Do you know good mini, but the straight one, not L shape?

Bought in US a few years ago I think I saw similar case in Farnell catalog, will let you know when I got the order code. Sure, but would be better if we can find a quieter place