i'm on a roll... the kgsshv

[luvdunhill]

You can order the LSK170s from diyaudio at ~$18 for a set of 8. Not sure how these typically match up; I know Spritzer said the LSJ74s were all over the place for Idss.

I have an ad here with a large lot. I can't mail them for a while though.

[insanity]

I don't really know where to post this, but since I didn't want to open a new thread for it, I thought I'd try here. 

I have a luxury problem 

 

I recently acquired a quad rk50 pot. Now I am asking myself, what I could use it for (very logical I know  , buy first, think later). 

So my question is the following: Would it make sence to build a passive preamp with it to go between my Invicta (which has a very good digital volume control) and my amps (KGST with alpha pot and KGSSHV with an Elma stepper)? This way I could turn both volume controls in the amps to max and just use the rk50 for both, with the capability to fine trim the amps with their integrated volume control. 

 

Another option would be to replace the elma stepper in the KGSSHV with the RK50. 

 

Furthermore I have a midterm project to build an offboard KGSSHV, which I have only acquired boards for until now. So I could put it in there. 

 

I would love to have a BHSE. But I don't want to do the part sourcing... Same for the T2. 

 

Any comments?

 

Note to self: The RK50 is so beautiful ;-)

Edited March 15, 2015 by insanity

[Nifrigel]

Greetings!

 

I've recently acquired Mjolnir's KGSSHV (Thanks, Birgir!). I've noticed that every time I turn the amp off, the headphones make some clicking electrical noise. I've recorded the video to illustrate what I'm talking about: 

Here is the audio-only version (the sound is much more clear there): http://vocaroo.com/i/s1RAotvyJMin

 

It seems that the amp's capacitors are discharging on the headphone's diaphragm. Now I'm a bit worried, is this dangerous for the headphones? Does anybody else have the same problem (if it should be considered a problem) with their KGSSHV?

[spritzer]

This is common for the circuit and poses no harm for the headphones. 

[DefQon]

I don't really know where to post this, but since I didn't want to open a new thread for it, I thought I'd try here.

I have a luxury problem

I recently acquired a quad rk50 pot. Now I am asking myself, what I could use it for (very logical I know , buy first, think later).

So my question is the following: Would it make sence to build a passive preamp with it to go between my Invicta (which has a very good digital volume control) and my amps (KGST with alpha pot and KGSSHV with an Elma stepper)? This way I could turn both volume controls in the amps to max and just use the rk50 for both, with the capability to fine trim the amps with their integrated volume control.

Another option would be to replace the elma stepper in the KGSSHV with the RK50.

Furthermore I have a midterm project to build an offboard KGSSHV, which I have only acquired boards for until now. So I could put it in there.

I would love to have a BHSE. But I don't want to do the part sourcing... Same for the T2.

Any comments?

Note to self: The RK50 is so beautiful ;-)

Sell me the rk50.

[insanity]

What would you use it for?

 

Any other input is also appreciated.

[spritzer]

I use mine as paperweights...   

[insanity]

[spritzer]

Yup, they were bought for projects which haven't materialized yet. 

[mwl168]

Hi Birgir:

 

This is a topic we exchanged over at the KGST thread but I thought this is the proper thread to continue this discussion regarding the kgsshvpsminifinalstn9360 PSU.

 

To quote your post: " You can use that PSU ( kgsshvpsminifinalstn9360) you could have problems.  Plus nobody has ever built that PSU there might be massive problems.  I just found out over the weekend that the layout software we use has a brand new way of fucking us over with no warning. "

 

I just completed a KGSSHV GB using the kgsshvpsminifinalstn9360 for PSU. Do you have advice what we should be looking out for when we build this PSU?

 

Thanks!

[spritzer]

No, not really.  It should work but a trace might be deleted by mistake (that has happened) and then all hell breaks loose.  Just fire one up and see if it works. 

[mwl168]

Thanks Birgir.

 

I got my kgsshvpsminifinalstn9360 board mostly populated but need a few parts to complete. I can be the guinea pig for this board unless someone beat me to it 

[spritzer]

It should be ok but one never knows until the switch is flipped for the first time. 

[johnwmclean]

As a rule of thumb, check the unpopulated boards for shorts with the schematic.

[JimL]

I'd power up using a variac on the AC line, monitoring voltages as you go so if there is a major error you can power down before it blows up.

[mwl168]

Using a multimeter's connectivity test, I am tracing the kgsshvpsminifinalstn9360 PCB against kgsshvps8g schematic.

So far, I've found a discrepancy: on the +450V rail: the 24V diode (D1) across Q10 and is duplicated on Q9 on the PCB but not on the schematic. Ditto on the -450V rail. I assume the PCB is correct and the kgsshvps8g schematic needs to be corrected.

Can Kevin, Birgir or someone with knowledge of the circuit verify and confirm?

I will continue my tracing and continue to report discrepancies or questions.

Thanks!

Edited March 17, 2015 by mwl168

[johnwmclean]

That’s correct 2 x 24V diodes for each rail.

 

I’ve built the previous version 1.0 of this board, as far as I can tell the only differences between versions 1.0 and 1.1 is silkscreen, and a 300K resistor trace has been moved around a 1mm.

 

Flip the switch already! 

[eggil]

kaboom!!!

[mwl168]

That’s correct 2 x 24V diodes for each rail.

 

I’ve built the previous version 1.0 of this board, as far as I can tell the only differences between versions 1.0 and 1.1 is silkscreen, and a 300K resistor trace has been moved around a 1mm.

 

Flip the switch already! 

Good to hear John. Hope you are right.

I am done tracing the PCB against the schematic, cannot be 100% sure and I don't know quite how to verify the LT1021 voltage reference, but the only discrpency I did find was the 24V zener I mentioned in my last post.

The missing parts I ordered should arrive in a few days then I'll be able to finish up and "flip the switch". We'll see If it goes kaboom!

[nopants]

use a variac

[Pars]

I have a variac you are welcome to borrow. Just pay shipping. My brother lives in the Twin Cities and can retrieve, so just one way on the shipping.

[mwl168]

Thanks Pars for the kind offer. I may take you up on your offer.

I have a few extra transfomers with much lower voltage secondaries. Is it possible to test the PSU by hooking it up to a lower voltage transformer just to test if there are catastrophic problems? If so, what's the minimum secondary needed to test it?

[eggil]

This may not be a fancy variac, but is quite cheap. I have been using it for a couple of years without any trouble.

 

http://www.ebay.com/itm/Variable-AC-Transformer-500VA-Variac-0-130V-TDGC2-0-5-/381177619548

Edited March 18, 2015 by eggil

[Earspeakers]

I always use a variac, bring it up slow, put clips on the output and watch what it does as you come up, go slow and test intermediate points too. Having multiple DVM's helps. 

[mwl168]

That’s correct 2 x 24V diodes for each rail.

 

I’ve built the previous version 1.0 of this board, as far as I can tell the only differences between versions 1.0 and 1.1 is silkscreen, and a 300K resistor trace has been moved around a 1mm.

 

Flip the switch already! 

Hi John:

Can you check on your version 1.0 PSU board, where does the V in, V out and GND pins of the LT1021 connect to?

On the stn9360 board, the V out pins connect to base of Q3 and Q15, the GND pins connect to ground and -450V. But I cannot figure out where does the V in pins connect to. It seems they don't connect to any thing.

Thanks!