Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: p2pAmps on August 23, 2015, 09:31:33 am

Title: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on August 23, 2015, 09:31:33 am
Well I had so much fun building the first PR I decided to do a build for buddy of mine who was begging to buy mine (NFS)...

Here it is so far.  This one is going faster as I learned a few things from #001

(http://p2pamps.com/kbpr/1.jpg)
(http://p2pamps.com/kbpr/2.jpg)
(http://p2pamps.com/kbpr/3.jpg)
(http://p2pamps.com/kbpr/4.jpg)
(http://p2pamps.com/kbpr/5.jpg)
(http://p2pamps.com/kbpr/6.jpg)
(http://p2pamps.com/kbpr/7.jpg)
(http://p2pamps.com/kbpr/8.jpg)
(http://p2pamps.com/kbpr/9.jpg)
(http://p2pamps.com/kbpr/10.jpg)
Title: Re: Hoffman Princeton Reverb Build #002
Post by: plaidzebra on August 23, 2015, 09:47:19 am
Ooh, can't wait to see how well this one turns out! Your other build was fantastic :icon_biggrin:
Title: Re: Hoffman Princeton Reverb Build #002
Post by: EL34 on August 24, 2015, 05:04:21 pm
Haaa, finally someone who wires the board first and then adds the parts  :icon_biggrin:


This gives you the added advantage of cleaning off any flux spots after the wiring
And you don't bend the wires on the components by trying to twist wire around a turret that has a part on it already


Looking good so far Mike


Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on August 24, 2015, 07:24:12 pm
Thanks Doug, trying to work smarter and not harder...
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on August 28, 2015, 06:44:46 am
Made a little more progress:

(http://p2pamps.com/kbpr/11.jpg)
(http://p2pamps.com/kbpr/12.jpg)
(http://p2pamps.com/kbpr/13.jpg)
(http://p2pamps.com/kbpr/14.jpg)
Title: Re: Hoffman Princeton Reverb Build #002
Post by: EL34 on August 28, 2015, 06:51:48 am
Looks great Mike
very clean'

Now is the time to get those flux sprays off the board







Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on August 28, 2015, 06:56:08 am
Thanks Doug.  I will finish wiring and doing the pots etc, (double check all work twice) clean that board good, and install all the components... 
Title: Re: Hoffman Princeton Reverb Build #002
Post by: EL34 on August 28, 2015, 06:58:17 am
Nice!
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on August 28, 2015, 01:48:02 pm
Fast forward

(http://p2pamps.com/kbpr/21.jpg)
Title: Re: Hoffman Princeton Reverb Build #002
Post by: EL34 on August 28, 2015, 02:30:46 pm
Now that's clean!


Nice work Mike  :bravo1:
Title: Re: Hoffman Princeton Reverb Build #002
Post by: tubeswell on August 28, 2015, 03:49:22 pm
Very tidy
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on August 28, 2015, 03:54:17 pm
Thanks Doug, I really appreciate you sir.

Well, the chassis is all done now.  My own personal way I do a QA before I fire it is I check every connection and value and when I am 100% sure I am good I hit it with red lacquer.  I fired it and it worked perfect.  All the voltages are perfect, bias @ 27mA, and even the reverb works this time Doug LOL...  Soon as the cabinet gets here we will have an amp...

Note: I swapped the 1M resistor in the tremolo for a 220K to gain a little more intensity.  I also wrapped the 100K plate load resistors as they were crossing over a ground buss and I got weird about that.  Just my OCD kicking in...

(http://p2pamps.com/kbpr/26.jpg)
(http://p2pamps.com/kbpr/27.jpg)
(http://p2pamps.com/kbpr/28.jpg)
(http://p2pamps.com/kbpr/29.jpg)
(http://p2pamps.com/kbpr/30.jpg)
Title: Re: Hoffman Princeton Reverb Build #002
Post by: EL34 on August 28, 2015, 05:30:06 pm
Looks great

Not a bad idea on the plate load resistors that cross above the ground buss.
Whatever makes you feel good about your build

I am not a fan of the red goop, but to each his own on that deal  :icon_biggrin:

Title: Re: Hoffman Princeton Reverb Build #002
Post by: Willabe on August 28, 2015, 05:54:29 pm
Looks great!    :icon_biggrin:

Why the Mojo .003 cap? I thought Jupiter makes that value.

I am not a fan of the red goop, but to each his own on that deal  :icon_biggrin:

That might be a problem if/when someone goes to change something?
Title: Re: Hoffman Princeton Reverb Build #002
Post by: EL34 on August 28, 2015, 06:27:03 pm
Quote
Why the Mojo .003 cap? I thought Jupiter makes that value.

I stock the Jupiter caps now

Don't know if you guys saw the announcement here
http://el34world.com/Forum/index.php?topic=19086.0 (http://el34world.com/Forum/index.php?topic=19086.0)

Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on August 28, 2015, 06:27:25 pm
Looks great

Not a bad idea on the plate load resistors that cross above the ground buss.
Whatever makes you feel good about your build

I am not a fan of the red goop, but to each his own on that deal  :icon_biggrin:

The red goop is really very thin lacquer Doug and doesn't have any conductivity issues at all. 

(http://p2pamps.com/goop.jpg)
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on August 28, 2015, 06:39:24 pm
Looks great!    :icon_biggrin:

Why the Mojo .003 cap? I thought Jupiter makes that value.

I am not a fan of the red goop, but to each his own on that deal  :icon_biggrin:

That might be a problem if/when someone goes to change something?

I used the vitamin T mojo cap because I had it on hand...
Title: Re: Hoffman Princeton Reverb Build #002
Post by: HotBluePlates on August 28, 2015, 06:48:39 pm
Another beautiful build!
Title: Re: Hoffman Princeton Reverb Build #002
Post by: sluckey on August 28, 2015, 07:58:55 pm
Another good job. That's a fancy reverb bag too!  :thumbsup:
Title: Re: Hoffman Princeton Reverb Build #002
Post by: SleepLess on September 01, 2015, 10:21:05 am
Excellent build! I see you swapped the 1M tremolo resistor for a 220K. Great option, I love that one! Have fun!
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on September 01, 2015, 10:23:58 am
Excellent build! I see you swapped the 1M tremolo resistor for a 220K. Great option, I love that one! Have fun!

I did swap the 1M out on #001 too.  It's nice to have the option to get deep intensity if I want or need it.  I rounded up some very nice 6V6s yesterday so I will be giving those a whirl too and see if I hear a difference.  In the meantime my wife has me woodshop-ing for her.  Getting ready to make a Big Green Egg table...
Title: Re: Hoffman Princeton Reverb Build #002
Post by: Willabe on September 01, 2015, 10:59:11 am
Oh man, you have a big green egg?

I rrreeeaaaalllllyyyyyy want one of those!!!!!!!!
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on September 01, 2015, 11:01:57 am
Oh man, you have a big green egg?

I rrreeeaaaalllllyyyyyy want one of those!!!!!!!!

It's a new addition to the family.  Still in the box waiting for me to build it's nest :)
Title: Re: Hoffman Princeton Reverb Build #002
Post by: eleventeen on September 01, 2015, 08:46:59 pm
"Still in the box waiting for me to build it's nest :)"


I can't imagine I have to tell you that those things can get incredibly hot...like 800 degrees F. Was just talking with some buds and one of them got one. I couldn't believe the thermometer on it. Yes, they can get fearsome hot, asbestos suit hot.


Glad you added the black Fender back panel overlay on your excellent build. One of them things. Beautiful build, congrats!
Title: Re: Hoffman Princeton Reverb Build #002
Post by: Willabe on September 01, 2015, 09:23:54 pm
Maybe so but the beauty of big green egg type grills/smokers is that they only need ~ a couple of chimney starters worth of charcoal briquettes to slow smoke a whole brisket or whole pork shoulder, 8 to 12 hours at ~250, instead of 2 to 2 1/2 bags. Not to mention all the running back and forth to check the coils and start a new batch at the right time.


             :blob8:   
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on September 02, 2015, 05:24:52 am
"Still in the box waiting for me to build it's nest :)"


I can't imagine I have to tell you that those things can get incredibly hot...like 800 degrees F. Was just talking with some buds and one of them got one. I couldn't believe the thermometer on it. Yes, they can get fearsome hot, asbestos suit hot.


Glad you added the black Fender back panel overlay on your excellent build. One of them things. Beautiful build, congrats!

Yeah they can get very hot but oddly enough mostly on the inside.  You can put your hand on the outside and while you can't leave it there a long time, it will not burn you.  I still have much to discover with the Egg...
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on September 03, 2015, 10:01:42 pm
(http://p2pamps.com/pr.jpg)

All done now
Title: Re: Hoffman Princeton Reverb Build #002
Post by: purpletele on September 03, 2015, 10:09:40 pm
That is cool!

I bet is sounds great.
Title: Re: Hoffman Princeton Reverb Build #002
Post by: EL34 on September 04, 2015, 06:35:37 am
Looks great Mike


More sounds clips coming?
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on September 04, 2015, 09:52:42 am
Looks great Mike


More sounds clips coming?

Hey thanks Doug...  I am going to have the new owner (My good Bud) make a video when he gets it so we can hear it with his speaker in it.  I still don't know what he will end up using so it will be a surprise to me too. 
Title: Re: Hoffman Princeton Reverb Build #002
Post by: DummyLoad on September 04, 2015, 10:00:00 am
I still don't know what he will end up using so it will be a surprise to me too.

jbl d120 or k120!  :icon_biggrin:

very nice build.

--pete
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on September 04, 2015, 10:05:36 am
I still don't know what he will end up using so it will be a surprise to me too.

jbl d120 or k120!  :icon_biggrin:

very nice build.

--pete

He is talking about an EV12....  We'll see
Title: Re: Hoffman Princeton Reverb Build #002
Post by: DummyLoad on September 04, 2015, 12:09:16 pm
I still don't know what he will end up using so it will be a surprise to me too.

jbl d120 or k120!  :icon_biggrin:

very nice build.

--pete

He is talking about an EV12....  We'll see


i love those too. have a cabinet i had custom made loaded with a EV12L and EV15L. still, the JBLs edge it out in my taste preference. the jbl's in decent condition are becoming scarce though, so there's that to contend with. EV 12L are still in production and that's why i lean in the EV direction now.


--pete
Title: Re: Hoffman Princeton Reverb Build #002
Post by: rhodco on September 07, 2015, 04:19:21 pm
Hey Mike,

I just have a question about your choice for the value of R63 in the Tremolo circuit. I noticed that Doug used 1M in the original example, then commented that it could be altered according to personal preference. You chose to put a 220K in that position for your build. Are you pleased with those results? Would you recommend going any higher or lower in value for that resistor?

Just trying to gather all the knowledge I can from you guys before I order the parts and start building mine.

Thanks,

Cliff

Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on September 07, 2015, 06:54:05 pm
I swapped out that 1M for a 220K to get way more thump.  220K is a little too much now that I did it so I just don't turn it up as far and its fine.  I think a 470K is a good choice too.  Try it out and see what you think, it is kinda personal taste.

Cheers
Title: Re: Hoffman Princeton Reverb Build #002
Post by: rhodco on September 08, 2015, 11:30:31 am
I happen to have one of these TO20 output transformers: http://www.allenamps.com/parts.php#transformers (http://www.allenamps.com/parts.php#transformers)

 and I'm wondering how that compares to the Classic Tone 40-18038. Both are spec'd at 6600 to 8 ohms but the Allen seems to be thicker and heavier. My plan is to drive a 12" Weber 12F150T, or Celestion Gold speaker.

 
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on September 08, 2015, 12:42:08 pm
I happen to have one of these TO20 output transformers: http://www.allenamps.com/parts.php#transformers (http://www.allenamps.com/parts.php#transformers)

 and I'm wondering how that compares to the Classic Tone 40-18038. Both are spec'd at 6600 to 8 ohms but the Allen seems to be thicker and heavier. My plan is to drive a 12" Weber 12F150T, or Celestion Gold speaker.

I am not sure about Allen's OT but word has it they are great.  I just never personally used one as I kinda stay with what I know so far.  I am never opposed to trying new things however.  I bet you can't go wrong with either...
Title: Re: Hoffman Princeton Reverb Build #002
Post by: rhodco on September 08, 2015, 12:54:58 pm
I've just watched your YouTube video of this amp about 5 or 6 times now - https://www.youtube.com/watch?v=3mb3ig0S11U (https://www.youtube.com/watch?v=3mb3ig0S11U)

I really, really like that tone. You did an amazing job. I'm starting to question my choice of speaker now. That Warehouse G12C/S sounds really good!

Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on September 08, 2015, 12:59:45 pm
So far the Warehouse has been good, a little tight, but it is brand new.  I want to try an Orange Fender D120F for fun.  Did a session a few days ago with PR and it shined bigtime. 

So don't wait, just order the parts from Doug and build yourself one.  Call it a early Birthday/Xmas gift :)
Title: Re: Hoffman Princeton Reverb Build #002
Post by: p2pAmps on September 11, 2015, 10:34:30 am
Well, here is the happy new owner and good buddy doing a little demo on PR #002

https://www.youtube.com/watch?v=2OdXeAX6yAw (https://www.youtube.com/watch?v=2OdXeAX6yAw)

https://www.youtube.com/watch?v=xhlG1Z6JcwQ (https://www.youtube.com/watch?v=xhlG1Z6JcwQ)
Title: Re: Hoffman Princeton Reverb Build #002
Post by: Fresh_Start on September 12, 2015, 08:26:47 am
Too bad your buddy can't play a lick...  Holy cow!



 :bravo1:


Chip