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Gints
Reply with quote  #1 
Hi Guys,

First time building, and suitably nervous about firing up to nothing, or worse, amp destruction.

I am up to Step 35 in the build, and thought maybe a good time to share some pics before everything gets over-cluttered and difficult.

I have been slow and methodical, but I am interested if anyone can observe any mistakes in my work this far. Note I am running this 240V for AUS.

Any feedback or tips at this point of the build would be appreciated. I am so excited!

Attached Images
Click image for larger version - Name: SOB_240V_Step35.jpg, Views: 114, Size: 1.62 MB 

Gints
Reply with quote  #2 
One other question.

Once the build is complete, the instructions are basically 'Turn it on and bias it'. Are there any recommended steps to check everything is working properly before this step is taken? Checking any voltages without tubes etc.?
Eric C.
Reply with quote  #3 
I used a pair of inexpensive speakers to test on. Everything is working fine at first poweron.

But it will always be good to double check your work. I did find a couple of mistakes.


Quote:
Originally Posted by Gints
One other question.

Once the build is complete, the instructions are basically 'Turn it on and bias it'. Are there any recommended steps to check everything is working properly before this step is taken? Checking any voltages without tubes etc.?
Mel
Reply with quote  #4 
I wouldn't rely on anyone advising you, based on your photo, on whether you've done a proper job in the hookups. The manual already contains photos for each and every step, so compare what you've done to it, and only you can verify and confirm that you've done a proper job.

I recently completed both the SOB and MP, and my main tip is to double and triple check each and every step. Use a marker pen or pencil to check against each step and each component or wire you hook up AND then do a second tick (or whatever) to confirm that you have soldered everything for that terminal tab.

It is easy to miss soldering a terminal tab especially when there are multiple components and wires hooked up to it. And... even when you have soldered that terminal tab, be aware that the solder may not have melted sufficiently to reach the bottom-most lead or wire hooked up to that tab. It may look as though the whole bundle is soldered, but it can be hidden from sight by the upper leads and wires.

It helps to scan ahead of the instructions to look for additional hook-ups for that terminal tab so you get an idea of how many other leads and wires are supposed to be attached to it.

Strictly speaking, it would have been better if voltages were given for critical points in the circuit to be checked and verified against your build, but if you have made no errors in component values and have measured each component before soldering to ensure that it is of the correct value, you should not have to worry about the measured values.

And if you do intend to stick your multimeter in to do any measurements, please  remember to set the multimeter to measure DC and not AC! (unless you wanted to measure your mains voltage). The other usual safety warnings always apply.

Have fun and do give your listening impressions of the amp.
Gints
Reply with quote  #5 
Yes I have been super triple checking everything, very anal and slow.

Can't wait to hear it 😀
carson
Reply with quote  #6 
once complete, take the 15 to 30 minutes and trace the schematic with your work while following the directions; you will learn a lot while completing this check.
Gints
Reply with quote  #7 
I'm finally finished and went to fire up, then... I couldn't get 2 of the ECC81 in. The holes in the tube mount appear to be obstructed! I looked inside and the back of them is sealed with pins into plastic, so I don't think I have caused it.

Has anyone seen this before? Ideas? Am I stupid?

Attached Images
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Bruce Rozenblit
Reply with quote  #8 
Try to take a needle and see if you can clear out whatever is in there.
Gints
Reply with quote  #9 
All sorted - stray solder that I sucked out. My fault.

Turned on, fired up, bias stable, and sound is AMAZING even without the preamp. One satisfied customer, now onto building the masterpiece😀

Attached Images
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SONDEK
Reply with quote  #10 
Way to go GINTS!  Well done!

I remember just how good it feels to build one of these kitsets for the very first time - then to fire it up and the bloody thing actually works superbly!

(One of the best feelings EVER...)

Kudo to Bruce for producing Industry-leading amp kits PLUS Best-of-Breed instructions!

Nice work!
[biggrin][rofl][biggrin]

-SONDEK


Gints
Reply with quote  #11 
Quote:
Originally Posted by SONDEK
Way to go GINTS!  Well done!

I remember just how good it feels to build one of these kitsets for the very first time - then to fire it up and the bloody thing actually works superbly!

(One of the best feelings EVER...)

Kudo to Bruce for producing Industry-leading amp kits PLUS Best-of-Breed instructions!

Nice work!
[biggrin][rofl][biggrin]

-SONDEK




Thanks mate. I had conditioned myself to be ready for disappointment and rework, so it was an even better feeling when it just sung.

There is a nice satisfaction knowing that you put it all together, and a healthy respect to Bruce for the quality of design, instruction and components 😀
Mel
Reply with quote  #12 
Congrats Gints on successfully completing the whole build out! What a wonderful feeling, right?

And the reward is even sweeter when the music starts playing and you go, "wow... !" The sense of airiness and cleanness of the music is what hit me first, then the timbre and eeriness of hearing the vocals sound so convincingly real. Big and open and deeper soundstage is also what I got.

Build your MP kit, and you will experience another "wow!!" moment... 

But... I will say that if like mine, your kit has those brown mylar (a.k.a. polyester) coupling caps instead of the white or yellow cylindrical polypropylene caps as shown in the photos in the manual, then I highly recommend that you replace them with decent polypropylene caps in both the SOB and MP. I have found that unless polyester caps are from the reputable brands, they can sound awful especially in certain coupling positions.

When you are ready to do these cap changes, I can describe what my results were, and what changes resulted. For now, I will say that these cap upgrades brought everything a huge leap forward for me. YMMV of course, since they are indeed dependent on the system you have, but I don't have a super high end system, just great value components that sound great, exactly like how the SOB and MP are.

Have fun and please do keep us updated with your progress on the MP preamp.

Mel


Carson
Reply with quote  #13 
Great work! And when you add a 300B tube to the mix...that’s when the magic happens!

I will admit, I’ve changed the polyester caps in my SOB, however I recommend you listen to what Bruce wanted you to hear, for hours and hours (hundreds) so you have a designed reference.
Mel
Reply with quote  #14 
The brown-dipped polyester caps were in more critical need of replacement in the MP than in the SOB, especially the 0.1uf coupling cap.

I tried living with the original caps and it was bad in the MP. So much so I wrote to Bruce and ask if there was something wrong with the kit, and he of course rightly said that he has had no complaints... so I put it down to the fact that my previous preamp had me spoilt and I was expecting a much better sound... Thankfully, I had caps of basically the right value with me, and I replaced the brown polyesters and bam! Everything just opened up and I was just astounded at how much better it sounded: clarity, transparency, just the meatiness of the sound that had that roundness and body that I guess is what some call sweetness of the 300B, and the size of the soundstage.

So.. yeah, do listen to how the original kits sound for a few days, but I highly recommend doing some replacements. I've been rolling different kinds of caps in both the MP and SOB, and it has been fun and very rewarding.

Mel
AndrewT
Reply with quote  #15 
Quote:
Originally Posted by Mel
The brown-dipped polyester caps were in more critical need of replacement in the MP than in the SOB, especially the 0.1uf coupling cap.

I tried living with the original caps and it was bad in the MP. So much so I wrote to Bruce and ask if there was something wrong with the kit, and he of course rightly said that he has had no complaints... so I put it down to the fact that my previous preamp had me spoilt and I was expecting a much better sound... Thankfully, I had caps of basically the right value with me, and I replaced the brown polyesters and bam! Everything just opened up and I was just astounded at how much better it sounded: clarity, transparency, just the meatiness of the sound that had that roundness and body that I guess is what some call sweetness of the 300B, and the size of the soundstage.

So.. yeah, do listen to how the original kits sound for a few days, but I highly recommend doing some replacements. I've been rolling different kinds of caps in both the MP and SOB, and it has been fun and very rewarding.

Mel


What did you replace the caps with Mel? would be interested to perform a similar experiment.
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