jose

LSK489/LSJ689 looks good but I can't find where to buy them... OK, I only find trendsetter but shipping costs are terrible.

Any recommendations for dual Jet or dual bipolar? soon I will start my Dynalobal and I want to buying for components to test in both amps.

Do you have the cold channels bridge to ground? Edit: and volumen pot to 0

I would like to experiment with something like that.

1/8w? Do you have the BOM? You should use 1/4w

Thanks for the answers and photos guys. I also use Mill-Max sockets so I discard a connection problem... but yesterday I was thinking of soldering a THAT with noise to a socket and try this again. I have nothing to lose. Maybe I bought a lot with some kind of problems I bought 6 units I had 3 with issues. However, now I like the idea of using two set of 2SK170/2SJ74GR. This is a more expensive solution but I have units for this. Those who have tried this, what do you prefer? I mean use a THAT or JFETS. Thanks

A very special album for me; David Gilmour "On An Island" Remember that night...

Thanks Dr. Gilmore. My ampli sounds amazing in both SE and Balanced, but as I can change the THAT by another solution. I have several Jfets in my "warehouse" so I'm tempted to make a small mini-plate for them.

I have been reviewing the entire pcb and I have not encountered any problems. Solder is OK, resistors, sand seemed intact too. So I installed the board and decided to change the THAT340 as it´s the easiest component to replace and the most prone to make noises and ... Bingo! Totally silent. Fortunately, I placed these components on the bases. This is the third THAT340 that I change by different noises. Has anyone else had problems with them? I've bought it at Mouser so they are original.

This old XRCD: Reiner and Chicago Symphony Orchestra, Tchaikovsky: 1812 Overture

Sorry Pars, I have dismantled the channel and I am checking the solders but for the moment I have not found anything strange. I asked you about TRS gorund because with this ampli I worked hard to avoid the ground loops.

It's a gift from my wife. She bought it at David Gilmour's official store. Comes a pack of 4 vinyls and 2 CDs.

I have checked the wiring and there aren´t problems but since I am doing things, I have a XLR 4 pin output conector and a TRS. What is the most appropriate way to connect the TRS ground? From the TRS to ground of any Sigma22 or join the cold outputs into TRS ground. ¿?

I´m working on input wires and tomorrow I check both boards in search of some problem with solders. I wish it were just that! The sound is so low that my oscilloscope can not detect it so I can´t show you any measure. However, at the moment I am also looking for a couple of boards (see 1.4 on board) in case I have to replace any.

Bias at 370/365mVolt. Offset is most stable, arround -10~30 mVolt. Now I only have noise on R channel. Noise is like a crackling and you can hear very low . With bal or SE I have the same kind of noise and with the same level. I'm sure it's not a ground noise.

Thanks Rumina. I have reviewed my documentation but only find the reference at 0.75 Volt but I'm regulating the Bias at 0.375 Volt and in a while I can tell something.

Well I like to think that with Héroes he were different.

Héroes del Silencio

I did not remember that my input board bridges the Cold channel with ground when I select the a SE channel. So that's not the problem.

Thanks for the answer boys Yes, I also think that having SE and balanced inputs brings a lot of versatility. In my Stax amps I always bypass the cold channel (I use input selectors with relés) in SE inputs, but in the dynahi I hadn't through necessary... remember that I heard the crackling noise yesterday and I have this amp for a long time. For the outputs, SE and balanced is also necessary by the different types of headphones that I have. Yes, I understand that it's a waste of energy and that even results in the longevity of the components but we aren't talking about using a Grado. In my case use my Dynahi with high impedance and/or an disgusting sensitivity.

Thanks spritzer. I'm working on it now. Let me check.

Because at the moment I haven't had problems with that. If it's the problem it's easy to solve but I doubt it's my problem. As for the output device (hope you like it more...), you're right I'm wrong they aren't mosfet.

Yesterday I was listening to my amp and I noticed a small sound coming from both channels, it's not constant and it's not perceived while listening music. It's a sound like "fried". I was listening SE input and SE output and I don't bridge the cold input to ground. I have been taking some measurements and BIAS is symmetric on both sides; 750/760 mVolt on R channel and 720/735 mVolt on L channel. On the contrary, offset drift a lot and I've never been able to keep it on 0 volt. It's always between -100~40 mVolt and 120~60 mVolt (without servo). With servo, the offset never exceed 20 mVolt. It has always seemed to me that Mosfets run too hot for an on-board assembly (Mosfet reach 90°) although I know that the maximum temperature is 150° but even so, components and the PCB also get very hot. I'm not sure where to start since I've changed the THAT and OPAs too and I still have the same noise. Can Mosfet be damaged? Or can the problem be elsewhere? Thanks