[kellvyn]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Right now, it looks like there may be 35 kits and perhaps 2-3 partial kits available late-January to early-February time frame.

Will there be any PCBs left over, and will they be available for purchase as a separate item? I was ready to buy one but missed my chance.

 

[amc]

Quote:

Originally Posted by the_equalizer /img/forum/go_quote.gif x2. And from several different angles... Are you sure you did not reverse the connection from the power supply? Off the top of my head, the tip or center of the PSU connector is positive (B+) and the ring goes to ground. cheers!

Hi Tomb / Equalizer,

I checked. Tip is the red wire in the following pictures and its going to the B+ pad. I even reversed them and tried again and I get the same measurements just negative instead of positive. Here are a bunch of angles of the top and sides of the board. Did not detach the heatsinks but can if need be for more pictures of the underside and to start removing parts - sigh...

Rear Panel Connections and wiring:
Attachment 24610 Attachment 24611

Board top and side:
Attachment 24609 Attachment 24613

Angles from sides and corners:
Attachment 24614 Attachment 24615 Attachment 24616 Attachment 24617 Attachment 24618 Attachment 24619

 

[tomb]

Quote:

Originally Posted by amc /img/forum/go_quote.gif Hi Tomb / Equalizer, I checked. Tip is the red wire in the following pictures and its going to the B+ pad. I even reversed them and tried again and I get the same measurements just negative instead of positive. Here are a bunch of angles of the top and sides of the board. Did not detach the heatsinks but can if need be for more pictures of the underside and to start removing parts - sigh...

I can't fault your work from what I see in the pics - you've done a good job!

However, it looks like maybe R13 is not soldered on one end - that's the resistor up against the power input terminal block. That resistor divides the voltage supply between the two tubes and may cause some of your symptoms if it's not soldered.

A second suspicion is your tube LEDs. Those leads look awfully fat. I'm not surprised that it took a pair of pliers to get them through those tube socket holes.

You may have an intermittent short if forcing them through did some damage. If R13 or any other resistor doesn't check out (check them all - for value, too), you might try de-soldering those leads, put some electrical tape on tips and see if that makes a difference when you turn the amp on.

Take a look at those things and let us know.

 

[gore.rubicon]

Is there an easy way to turn off the tube LEDs on the PCB build without desoldering? and what are some boutique modifications i can do with the PCB build?

 

[luvdunhill]

Quote:

Originally Posted by gore.rubicon /img/forum/go_quote.gif Is there an easy way to turn off the tube LEDs on the PCB build without desoldering? and what are some boutique modifications i can do with the PCB build?

does cutting wires count? that will definitely turn the tube LEDs off.

As for modifications, are you only interested in mods that don't require desoldering?

 

[dsavitsk]

Quote:

Originally Posted by gore.rubicon /img/forum/go_quote.gif and what are some boutique modifications i can do with the PCB build?

The two main ones I can think of are (1) replacing the plate load with a CCS of some sort (a LND150 could probably be made to work), and (2) you can probably DC couple the two stages together. The second one probably requires an adjustable cathode resistor, and a bit (perhaps a lot) of diligence in watching for tube drift. As a third (and fairly advanced -- don't try this unless you really know what you are doing) option, you can likely tie the cathode to the heater and run the heater current through Rk thus eliminating Ck and keeping rp in check. None of this has been tried, so it is definitely in the realm of experimentation.

 

[the_equalizer]

Quote:

Originally Posted by amc /img/forum/go_quote.gif Hi Tomb / Equalizer, I checked. Tip is the red wire in the following pictures and its going to the B+ pad. I even reversed them and tried again <snip>

Whoa! Don't do that. I was just asking you to make sure

. In some circuits reversing the PSU polarity can severely fry stuff so... don't do it.

Great pics, thanks! As TomB says, check R13, one of the pads does look as if it weren't soldered. If that doesn't solve it... what's the voltage across R4 (and across R10) ?

cheers!

 

[sourced]

Quote:

Originally Posted by the_equalizer /img/forum/go_quote.gif Congratulations ! It is indeed a warm fuzzy feeling to watch those tubes light up and hear sweet music coming out of the 'phones!! About the hum, I've found some 19J6's to be much more susceptible to hum than others; specially if you use high sensitivity 'phones. Swap the tubes and see if the hum follows the tube. If it does, well: it's the tube that it's at fault. On the channel imbalance, indeed, the most 'general' solution would be to use a better pot . Short of that you can try adding a couple input resistors as done in the PCB version. Take a look at the schematic. This solution won't make the imbalance dissapear, but it'll make it much less noticeable. cheers !

Man, what a night! I decided to bite the bullet and fix this hum issue. I took your recommendation and soldered in some input resistors (2 33ks in series for each channel). I was putting the tubes back in and heard a spark/pop or something... so I turned it on and the right tube did not warm up! I thought I might have fried the tube (which is really the worst case scenario, as it seems past my extra 2 they are in short supply). I swapped l/r tubes and it wasn't the tube, though. I then went to measure the mosfet voltages (this part's funny), and things didn't seem off. I had left a little bit of lead showing right under the mosfet packaging (above my electrical tape). ~23v at gate, 48 at drain, and ... whoops I let the probe touch the drain and source. The mosfet didn't take too kindly, and the fried voltages were 8v at gate, 31v at source, or so. NOT so good. So I desoldered/resoldered/liberally applied electrical tape.

The hum is now very minimal! Success. Thank you much, equalizer. I was worried for a second because I was hearing some hiss, but it's actually part of the music (!).

This did not magically make my pot better, as expected. Channel imbalance is about the same... I think I may be ordering parts for an M^3 soon (whoa there, I've just burned this in) so I can put an alps pot in there (we shall see). I'm looking on Mouser, is 688-RK27112A00AK the right kind? I realize it's 100kΩ instead of 50kΩ, but I don't see anything else on Mouser. If that's it, any recommendation on knobs? There appear to be thousands...

 

[bhjazz]

I have no idea when I started my P2P build. Obviously it was over a year ago. But then I moved, lost parts, found others...Gah! Anyway, my P2P build fired up on the first try last night. Sweet! The internals look like hell but it sounds great. And it obviously is quite powerful. I had eye-blinking tunes on last night for a very short time. Certainly power to spare which is fantastic. Once I get things cleaned up inside I'll post some pics. Lots of fun, and I had completely forgotten the total rush that is turning a creation on for the first time. Note to self: must get back to the amp backlog!

I do have a subtle amount of channel imbalance. Not sure if it's tubes yet until I can take some more measurements. I'll swap tubes once I get this right-side up.

Thanks for a great design, Pete, and thanks for all the fantastic support I see you doing, tomb!

 

[revolink24]

Does anyone here have any good guides that they know of for handling the different braids of the wires inside the SSMH? I was just revisiting it to fix the rats nest of wires inside it.

 

[Llama16]

I found the litz braid on chimeralabs, allthough i think that the pictures don't correspond with the explenation. But it's still very do-able. It could also be my own fault ofvourse, so plz someone correct me if so

 

[th3bl0b]

I finished putting together my p2p but the tubes don't light up when i turn it on. are they supposed to? i don't have an input or anything going into them yet, cause i can't find a rca to 3.5 mm (i have one in my apartment but i'm somewhere else for christmas break)...

 

[tomb]

Quote:

Originally Posted by th3bl0b /img/forum/go_quote.gif I finished putting together my p2p but the tubes don't light up when i turn it on. are they supposed to? i don't have an input or anything going into them yet, cause i can't find a rca to 3.5 mm (i have one in my apartment but i'm somewhere else for christmas break)...

Yes, the tubes are supposed to lightup. Better post some pics so we can take a look at what's going on.

Are you able to measure whether there's power coming from the walwart when you turn it on? The Cisco power supply has a very good circuit protector. If you have a short in your amp, it will simply refuse to supply voltage. Measured separately and disconnected, it will appear to function just fine under those circumstances. Try and measure from the wires coming from your power socket on the amp and see if it's supplying voltage.

 

[simwells]

Still no one know of a suitable pot with in built switch?

 

[tomb]

Quote:

Originally Posted by simwells Still no one know of a suitable pot with in built switch?

An RK097 would probably be a realistic option, but most are only available in 10K. You'd have to re-work your input resistor sizing accordingly. If you've used the PCB, the pin spacing is not going to match (there'd be more for the switch, anyway).