I have a somewhat weird question. How warm is your SU-6? When I just got my SU-6, I was quite surprised by how much heat it generated. It is not exactly hot, but significantly warmer than my DAC. Kind of class AB speaker amp warm. A few weeks later today, it is pretty much at room temperature...

Hi, sorry, haven't been checking this forum for a while. I saw your postings at diyaudio.com , I'd suggest you give one more shot at the preamp forum there, which is much more popular and active than its headphone forum. For me the puzzling thing is that why it affects both channels...

Sorry, this is beyond me. If you can't get help here, I suggest you head over to diyaudio.com. Post the schematic and the findings there, I'm sure the folks there can point you in the right direction. If you do, let me know, I am interested in knowing the outcome. Like I said, I suspect mine...

Assuming the DC spikes happen simultaneously on both channels (this can only be confirmed by you), I think the only possible scenario is the power supply, since that is the only place where both channels shares. This could be due to some instability in the ±15V regulation, however I think it is...

You can not measure DC on the output jack with the relay inline, you have to tap it before it hits the E12. However, if the DC transient is too fast you might not be able to measure it with a DMM, you need a scope for that. But if it stayed on for say a couple of seconds, this you can pick it...

Btw, did you implement the regal mod? Or the higher heater current mod? Mine used to trip often if I set the B+ or the current too high. Then it happens when I used 12BH7 that draw more heater current (300mA) than stock (150mA). I suspected it had to do with power instability. But now it seems...

Years back, I auditioned an SR-60 to see if it is for me. When I heard it, I went eww. It's congested congested and harsh. They are often touted as the rock can, I happen to be not that into rock. Thus since the beginning of this hobby, I thought Grado isn't for me. Fast forward to recently, I...

This been quiet for a while, allow me to bump this up. I build this Beta 22 a while back. The transformer was housed in another chassis. I wasn't entirely happy with it, but it at least had a proper chassis. Then I ripped it apart, and turned it to this. :D

I have a pair of 5963 and they should work fine. What is your voltage between TB+L and TPL (and the right side too). If I were to hazard a guess, there is something wrong with the either the CCS or the current mirror.

I see, those aren't 4 poles electrolytic.

You can not just ignore the other 2 poles of a 4 pole capacitor. 4 pole capacitor has separate input and output leads, 2 inputs and 2 outputs. Do read about them, you most likely won't be able to use them without modification to the PCB.

That is exactly what I meant by design fault. :D Most (if not all) modern equipments have relay that can cut off output at the event of power failure/cut-off. But you can argue that it was never designed for that purpose in the first place. :)

Mine does that too, and I wonder if it is a design flaw.

Quote:   Just need to replace the output transformer with an appropriate one.

You will want to keep the wire as short as possible, while keeping the cap body away from the tube and the heat sink. FWIW, mine is a bottom mount build. I have one lead attached to one hole and connected the other end with wire. You can then place the cap body in front of the heat sink or at...

Quote:   I got the case from a local store, it has no brand. The front panel is rather sharp in the edges.   Thank you for the kind words , but I am not sure if I deserve that.   On the top panel, the 3 big ventilation holes are off by 2 cm to the right due to calculation...

SOHA II, has been half naked for a while, finally covered it up. Kinda out of vogue here for a while. For some reason even DIY has FOTM here.            

Yes, the headphone amp serves as a pre amp, driving a power amp. The power amp is not grounded btw, it comes with a fixed 2 wires power cable. In the past I managed to make it dead silent by installing a power filter at the source and pre amp (I still have it). Just that for some reason, I no...

Not sure if we are on the same page. I have no hum with headphones, I just have hum when I am using my floorstanders as headphones :D, I have no hum too when I use the floorstanders as speakers. :D It's also not exactly a hum, more like white noise that has low frequency element, that varies...

I am using RCA clear top 12AU7A. Source is mainly Rega DAC through optical. Both the source and amp are behind power filter too. Any of you did the 300mA heater mod? This allows you to use more tubes, including the 12BH7 which some people swear by over any 12AU7 including the exotic ones. That...

Thanks guys, I thought no one is reading this. :D I managed to trace the problem, it was some bad solder joint. Btw, how did you guys do in the hum/buzz department? With my headphones it is pretty much silent, but I don't use any high sensitivity headphone at home. However if I use it as pre...

I am supposed to get at least 19V voltage drop between the power supply and the plate.   On one channel, I got about 27V of voltage drop, which is fine.   On another channel, I got about 1V. And of course that channel isn't working.   I swapped the tubes around, same thing. What is...

I actually finished putting together the parts. I used quite a bit of Elna Silmic II, it is obvious that the board weren't designed to use largish capacitors and it looked a bit hilarious to me.   Unfortunately, when I reach the last initialisation step I have a problem. I can not get get...

I understand that you are new in this. Nobody can tell you if something sounds good enough for you. If someone is really sure something is good enough for you, be very skeptical. HiFi is not like computers where someone can objectively tells you that this processor is better than the other one...

Quote: Really? I wonder what cable are you using? What is the marking on the cable says? Have you measured it?   The P cable has a lower inline resistor value and the S cable has a higher inline resistor value. And of course the driver impedance doesn't change. This is not only true...