[sceleratus]

Well the idiot went and got himself banned from the forum.
Thankfully the powers that be were gracious and let me back in.   I need to "just walk away" next time and after that.  I am sincerely thankful to be back because I enjoy Head-Fi.
 
I have some updates from the LA Meet to post but I'll wait until I'm better acclimated with being back in the general population.

 

[sceleratus]

The LA Meet was amazing.... that's what it's about.  Learning and sharing in person.  Putting faces to avatars, going over all those posts.
I was so drained, I really didn't network much.  At that point I was overwhelmed.  Yes Frank.... Holland, I'm sitting here and the iron is cold.
How in the world am I going to justify this ?????  with the boss?
 
The EH 300B's v. the JJ 300B's.  At first I loved the EH's ..  then after a while I'd listen to a favorite track and think  "there's something missing"  So after 2-3 days I rolled the JJ's back in and they were much bigger than the EH's.  Randy, that was really kind of you to let me try the EH's.
 
The experiment cooled my jets a bit on buying other 300B's.   I was looking hard at Emissions Labs,  But I'm not sure they will be a bang for the buck.   I need to relax and just listen to music for a while.
 
I my Schiit gear is gone with one exception.  I sold my Bifrost DAC and bought the Gungnir DAC.   I like that it's balanced and I will make some interconnects soon.  I have left over 20g a. silver wire.  I figured if that's what's inside might as well have it outside too.  Plus the iron will see some more action.  Which leads me to another ordering bungle.  The Neutrik XLR jacks came in yesterday.  One problem.  They are PCB.   doh
 
I also sold my RTC E188CC 1965 valves.  Those were my "end-game" valves with the Lyr.  Not so much in the DG 300B.  The 58' Bugle Boys, 58' Valvo PCC88's and some Orange Globes made in the UK all sound great, but the interesting part is they all sound different from each other while sounding great.  This was not the case with the Lyr.  There would be one dominant set of glass.
 
Today I received an amazing set of 1965 Amperex USN-CEP's  I've owned them before but sold them after the RTC's arrived.
This set is immaculate NOS.  The silks and box are perfect.   Straight away with little burning in.... they sound like they will be a significant step up from the others.
 
If anyone needs a set here is the AUDIOGON SELLER he has a few more matched sets.
 
I paid almost $300 the first time around.  These are much better for $225.  Very good seller too.

 

[sceleratus]

What do ya'll think of a DYI Amp Build Thread for Beginners" ?
 
It would require all you guys to get on board or it won't work.
Circuit geeks could suggest designs to build, why you choose them and provide some explanation of the circuits and their function.
 
My "area" of.... expertise...(that's a stretch) and others would be the physical build helping with how to order the wrong components and resources for getting the project completed.
 
Thoughts?

 

[Goobley]

I'd be happy to provide the knowledge and advice that I can to such a thread. It's always nice to have more solder slingers building projects. I've really enjoyed following your thread over the past few weeks.

 

[sceleratus]

Quote:

I'd be happy to provide the knowledge and advice that I can to such a thread. It's always nice to have more solder slingers building projects. I've really enjoyed following your thread over the past few weeks.

Cool.
 
Amps only.
My tastes are valve amps.   Probably tighten the discussion to valve amps.
Then we can have discussions on the integration of valve models.
 
And the other builders could get things going by discussing past and planned builds.  That would be the meat of the thread.  If it was just me it would be another rehash.  Yawn.  If it works it could be an amalgamation of builds similar to this thread.  All the describe all the ugly details and lots of photos.  I think talking about problems and "fail" is pretty cool.

 

[Goobley]

I think it could become useful resource. IMHO for beginners it may be a good idea to include hybrids as they are more approachable, but for your thread the decision is of course yours. I've just finished what I believe to be quite an interesting hybrid that I'd be happy to document in said thread. It should be fairly easy to build, the hard work was the design.

 

[muskyhuntr]

Interesting concept.  You have my interest.
 
Jim

 

[sceleratus]

Ok, so as long as it has a valve
I'll start it up today... Just have to wordsmith the opening post
No downside. Could be real popular.

Again. It will Only work if past builders step up and contribute .... Starting "first posts", not just waiting to answer questions.

 

[sceleratus]

Ya Jim, we need pic's

 

[sceleratus]

I put XLR source jack in today and I made a couple of cables (weave)  from the leftover 20g a. silver wire.
 
I have a new noise problem and I suspect the cables are acting as an antenna.
Backing up first.
 
The snow noise diminishes at times with playing time, but some ECC88's make it louder than others.  My new USN-CEP 6922 seemed louder.
 
Back to the XLR.
I cabled up my Schiit Gungnir and immediately got a loud transformer buzz type sound.  What was interesting is (let me remember) ..... If I jacked up the volume pot to the Max, then decreased the source volume (iTunes) both noises were virtually gone.  Dead quiet when you peg the pot.
 
Why I think there's an antenna ..... when I pull the xlr's at the Gungnir I get significant buzz.  If nothing is plugged into the XLR's lots of snow.
 
I was very careful not to flip neg and ground.  
On the RCA jacks I had center pin to one side of the pot, negative ring to the other side of the pot then continuing on to the board.  The pot sweeper was pos on the board.  At the board neg was jumped to shield.
 
The volume pot is an Alps Japan Blue log 10K pot.
 
With the XLR .... XLR Pin 2 replaced RCA Pos.  XLR 3 replaced RCA neg.  and XLR 1 went home run to the board replacing the jumper.
 
Suggestions...
 
Holland and Tom, remember in earlier discussions discussion on mitigation snow Tom said put in a 56 Ohm resistor on RCA pos / XLR 2.  I hadn't tried that because I wanted to get up and running.  I also remembered Holland thoughts that it might effect the sound.   Now with what's going on it may help.
 
General question...  Is it best to "peg" the source (iTunes) volume and keep the volume pot low or the opposite, turn iTunes way down and increase the volume pot.  That is what's working now.

 

[holland]

I'm not sure about iTunes, but I would max it out unless it's amplifying.  The reason is increased signal:noise.  I don't really use it, but when I use optical out of my macbook, and there's no volume adjustment.
 
Your cables need shielding, get some microphone cable as a cheap interconnect, until you find some shielded 3/4 conductor cable that you like (or not).  I like Mogami quad, or replicas as inexpensive cable as I'm not a $$$ cable believer.
 
I'm not sure about your wiring for the amp.  Are you using a single ended jack to XLR wiring scheme?  The Gungnir has true balanced outs and each jack carries a differential signal and ground.  The single ended output does a differential to single ended conversion, probably with opamps or a discrete circuit.  Are you using the input transformer on your amp or are you capacitor coupled?  The amp is not differential, and shorting a wire to ground may be causing problems, unless you are transformer coupled on the input.  Also, how did you wire the signals to the potentiometer?
 
Edit:  Can you take some pictures of the wiring, or draw out a schematic on paper and take a picture of it to post?

 

[sceleratus]

Quote:

I'm not sure about iTunes, but I would max it out unless it's amplifying.  The reason is increased signal:noise.  I don't really use it, but when I use optical out of my macbook, and there's no volume adjustment.
 
Your cables need shielding, get some microphone cable as a cheap interconnect, until you find some shielded 3/4 conductor cable that you like (or not).  I like Mogami quad, or replicas as inexpensive cable as I'm not a $$$ cable believer.
 
I'm not sure about your wiring for the amp.  Are you using a single ended jack to XLR wiring scheme?  The Gungnir has true balanced outs and each jack carries a differential signal and ground.  The single ended output does a differential to single ended conversion, probably with opamps or a discrete circuit.  Are you using the input transformer on your amp or are you capacitor coupled?  The amp is not differential, and shorting a wire to ground may be causing problems, unless you are transformer coupled on the input.  Also, how did you wire the signals to the potentiometer?
 
Edit:  Can you take some pictures of the wiring, or draw out a schematic on paper and take a picture of it to post?

Thanks Holland,
 
Lots of things for me to look into and respond.
It's a chore to lug 55 lgs up and down the stairs.
Tomorrow I'll pack up the valves bring it up and dig in again.
 
Unless I put the RCA's back I'm stuck with the bad cables until the new ones arrive.  I saw the Mogami on eBay and put them on a watch.  The seem like a nice intermediary price.  I don't want the gobs of $5 ones and I don't want $200
 
The lower right corner of the diagram is the input wiring....J7 / J3 on the Driver Board
I'll  get some close photos. 
 
 

 
 
 
 
 
 
 
 
 

 
 
 
 
 

 

[holland]

OK, looked at your amp picture a few pages back, you do have the input transformer, so the wiring should work (to the amp board).  I'd need to see how you wired the pot, and any additional resistors you added to handle 4-channels with a 2-channel pot.  It's doable, but it's not as common.
 
Some resistors in line, configuration B below.  Ideally, the pot would come after the input transformers for the amp.  You could point to point wire it, if it's easy to remove the transformer, or cut the trace and feed it in and out from the solder pads.
 

 

[sceleratus]

Many thanks....  I'll digest in the am.
 
Tom will probably weigh in, but he's been very busy with projects at work.

 

[sceleratus]

My back is pretty jacked up from moving the amp after putting in the XLR's so I haven't moved it and opened it up again.
 
What I found interesting is the noise come when resistance is introduced from the volume pot.  When it's wide open there isn't any resistance, correct?
Very low signal (from the Mac), very low noise.  
Large signal from the mac, more resistance applied by turning the volume pot down, more noise.
 
If I understand correctly, if I bypass the input transformers  that may help.
 
In the first tests, several weeks back, I only had toslink, now I have the Schiit USB card.  Either way I get the snow, perhaps more with USB.
 
I think there is an error in the following volume diagram.  The wiper belongs in the center terminal and the jumper is between the two outside terminals.  As depicted in the color diagram.   That is what worked with the RCA's
With the XLR, I kept pin 2 XLR (IN +) to the wiper, pin 3 (IN -)  to the top position of the block, and XLR pin 1 (Shield) to the bottom position.  Exactly as depicted in the color diagram.  So put the two together and that's how it's wired.