Three Hoffman AB763s down, one more on the bench

[bnwitt]

Well thanks to a little help from Sluckey I've got the First Hoffman DR up and running.  I had to do the 470k to 180k resistor change and the .1uf to .047uf capacitor change to get the Tremolo intensity where I wanted it but other than that, this amp sounds great just the way it is.  My friend will be thrilled.  I've already started #2 for the studio and I'm sure this one will go much more quickly.  I'll post some more pictures after I finish the burn in but here is one from the front and the layout of the amp.  Hopefully I'll get some good sound clips out of my guitar playing friend when he picks it up next week.  I think this next one will forgo any CC resistors.  Some of the CC resistors I bought back in 1995 had drifted up beyond their 5% tolerance just sitting in the plastic containers.
Barry

[Joel]

Carbon Comp resistors absorb moisture which causes them to drift out of tolerance.  You can gently bake them in an oven at 80 degrees C for 6 or more hours.  We used to do that in our workshop before soldering them onto a circuit board and coating with conformal coating to prevent further moisture absorption.

How did you make your faceplate?  That's the one part of my own amps I'm never happy with.

[bnwitt]

Once I have the chassis, I verify the spacing, draw a matching faceplate in Visio, print it to PDF then import it to Corel draw and finally save it in Corel draw version 11.  That file goes to Jeanne of BNP Laser (an engraving company) and she reverse engraves it on black material with white paint fill from behind.

[sluckey]

Looks good Barry. Did you use a pull switch on volume pot for the bright switch?

[Joel]

Thanks Barry.

[EL34]

Looks great

[bnwitt]

Looks good Barry. Did you use a pull switch on volume pot for the bright switch?

Sluckey,
Yes indeed, but only on the Tremolo channel.  It works great.  I didn't think he needed it on the normal channel.  I'll probably put it on the both channels of the one I'm building next though since it will be easier than the ripping out change I had to do post build on this one.  He's coming out sometime this next week to pick it up and has committed to doing some sound sample recording for me then.  I'll post those snippets when I have them.  I put a 160Kohm resistor and an 0.47uf cap in the tremolo circuit to boost the Tremolo intensity and kept the 6V6s at 70% idle.  With those changes the Tremolo is very strong.  I should have another 5 builds under my belt in a couple more weeks.  The second AB763, (2) Marshall 18 watts and the Marshall 2204.  Thanks again for all of your help on this one.
Barry

[bnwitt]

Thanks Barry.

My Pleasure Joel

Looks great

Thank you Doug.  I appreciate the kind words.

[Ritchie200]

Barry,

Very nice!  Can't wait to hear the soundclips!

Jim

[bnwitt]

Can't wait to hear the soundclips!
Jim

Me too.  I'm a pretty good acoustic finger picker but not so great on the electric or I'd do some myself.  I always appreciate one of these holy grail amps played by a good guitarist.  This guy's brother was a huge star in Germany(Chris Jones) and he's pretty good too.  I've attached a voltage chart of the amp if anyone is interested.
Barry

[bnwitt]

Ok, just getting started on the #2 DR.  Let's see how long this takes in between it and my RE work this week.
Barry

[sluckey]

I bet you're back up to speed now. Things get rusty when you stay away too long. Happens to all of us. 

[bnwitt]

Steve,
No doubt there was some rust on my chopsticks    It's all coming back to me now.  I decided to go through all my shop stock that I bought back before I found out that the way to make a million dollars in the amp business was to start with two million and crank out some amplifiers.  No sense in saving all this stuff.  Might as well get some great amps into the hands of some players again.

[shooter]

I found out that the way to make a million dollars in the amp business was to start with two million

with optimism like that you're bound to succeed, if you have money to burn, take up painting

[PRR]

> Ok, just getting started

I like that power strip; have owned a dozen. (Left some behind in a place that needed them more than me.)

I really like your lamp-limiter hack.

[Joel]

I was just admiring the power board with integral lamp limiter.  Very nice!  I think I'll have to steal that idea.

[bnwitt]

Thanks guys.  I love my multi-outlet surge protector with built in lamp limiter and the Belkin F9D1000-15 unit (having an all metal housing) was the best one available to put it in.  It's rugged and having the limiter right there (instead of separate) keeps me from cranking things up without one due to laziness.  I think I saw it somewhere on a website years ago and had to build one for myself.  Plus it has a 15' cord which is great.

https://www.newegg.com/Product/Product.aspx?Item=N82E16812107444&nm_mc=KNC-MSNSearch-PC&cm_mmc=KNC-MSNSearch-PC-_-pla-_-Surge+Protectors-_-Belkin-_-12107444

Barry

[bnwitt]

Well, I just had the 300kW PV project I was working on put on hold due to storm water plan issues until a discussion with the County plan checker happens.  So, I guess I have time today for some amping.  I just got the stand offs for the turret board located, drilled and installed so now it's time to load the board.  I learned a long time ago that it's best to do the standoffs before you install the turrets to avoid a rocking board when marking the stand off holes.  Let see what I can get done today.
Barry

[bnwitt]

now for the bus wiring of the board on my swiss cheese busing board.  Lots of boards have been bused on it.

[Ed_Chambley]

Far out Dude!  I don't really get rusty on amp stuff, my problem is I do goofy stuff like looking for an hour for the proper fuse.  Go buy one and when I open the fuse holder, I find the one I lost.


Oddly enough, I made a very similar bulb limiter, but mine only one row.


Really nice work!

[sluckey]

You got a butt load of extra turrets! You really need to build that AC-15 that you cranked me up on 5 years ago! 

[bnwitt]

You got a butt load of extra turrets! You really need to build that AC-15 that you cranked me up on 5 years ago! 

Yep.  That's on the list for me along with a Princeton.  I've got the pre drilled boards already.  I'm in a phase again.  I'll probably crank out at least 10 amps or more by the end of the year

[bnwitt]

Far out Dude!  I don't really get rusty on amp stuff, my problem is I do goofy stuff like looking for an hour for the proper fuse.  Go buy one and when I open the fuse holder, I find the one I lost.


Oddly enough, I made a very similar bulb limiter, but mine only one row.


Really nice work!

You know Ed,  because I have moved my shop from room to room so many times I find something I lost everyday.  Unfortunately, I seldom find what I started out looking for

[bnwitt]

Ok, I had to do some digging for parts in my mess of a shop but I finally came up with everything I need and am on my way to finishing the chassis of DR#2.  This one is going to have a minimum of CC resistors just to see if that has any effect which I doubt.  But, the good thing will be better values over time.  Hopefully I'll have the chassis done by this weekend and I can get starting building the combo cabinet.
Barry

[Ed_Chambley]

I bet I know where you can purchase a good supply of Carbon Comps, all neatly separated in Drawers.  Even up to 2 watters. 


Why can't you clean up you shop.  Not trying to mess with you as I would never do that.


Just ask Dave!


Build number 2 will probably sound better than 1.  I have a theory on carbon comps even though Dave Funk and RA say there is some distortion.  It is negligible as I have tested it.  I believe the noise that comes from them remind us of some of our oldest childhood memories of listening to old radio and record payers.  Generally these times were associated with pleasant experiences and the comfort of those around us.  Gave us a warm and fuzzy feeling.  So we equate this noise as warm and fuzzy.


Think about it the next time you fire up an amp like my Super Reverb that will fizzle and pop a little and then settle down once it gets warm.  BTW, the CC resistors in this amp are all 1 watters except the plates which are 2 watters.  They are getting ready for the trash.

[bnwitt]

I bet I know where you can purchase a good supply of Carbon Comps, all neatly separated in Drawers.  Even up to 2 watters. 

I think I'm done with them.  I have hundreds in plastic compartment boxes already

Why can't you clean up you shop.  Not trying to mess with you as I would never do that.   Just ask Dave!

I live with other people (wife and teenagers) who have ever shifting space demands and I keep getting evicted from said spaces.   As such I have been hesitant to get re-organized.  However, I think I now have a permanent space so I will get er' done.

Build number 2 will probably sound better than 1.  I have a theory on carbon comps even though Dave Funk and RA say there is some distortion.  It is negligible as I have tested it.  I believe the noise that comes from them reminds us of some of our oldest childhood memories of listening to old radio and record payers.  Generally these times were associated with pleasant experiences and the comfort of those around us.  Gave us a warm and fuzzy feeling.  So we equate this noise as warm and fuzzy.


Think about it the next time you fire up an amp like my Super Reverb that will fizzle and pop a little and then settle down once it gets warm.  BTW, the CC resistors in this amp are all 1 watters except the plates which are 2 watters.  They are getting ready for the trash.

I am in complete agreement.  I don't need the noise but mostly I don't need the up drifting values over time.  I have serviced some old Valco, Supro and other 50s era amplifiers and been astonished at the amount of value up drift in the CC resistors.  Some of the amps were non functional just due to that.  Of course I was obligated to replace CC with CC on these old amps but I think when building my own new holy grail amp clones I'm going to abandon CC from now on.  Back in the early 60s when my dad and I were servicing TVs and Radios the value up drift wasn't well known but with the passing of 40 years the way is clear.

[Ed_Chambley]

Well now I understand about organization and I really have no room to talk.  I am working on my new workstation, my 4th.  All of my things are all over there place, but I finally hit on a good plan I can live with.  When done (and this could be the day before i pass away I am not the fastest) I will post photos.


Quickly, I purchased 2 tool box side additions with drawers from top to bottom.  Set them 48" apart and built pegboard behind with strong magnetic bars on the lower portion and hooks on the upper.  You can actually throw a tool and it will stick to it.  In-between is a table that hooks to the cabinets.  Instead of making the table 30" high, I made it 36" which puts my Board Clamp closer to my eyes.  Exhaust vent above.  Of course, an adjustable height chair.


Anyway, it looks like you are getting back into the swing of building and it is looking good.  IMO, a Deluxe Reverb is a must have, but you got to build the AC15 you and Sluckey started.  I have built 7 of them now, but I built my personal one as a head.  I have been asked to build 4 more, but had to decline for now! 


My breadboard project keeps getting put off by silly little things like my Air Conditioner quitting, but in July Georgia air conditioning is a must!!!

[bnwitt]

...you got to build the AC15 you and Sluckey started.  I have built 7 of them now, ...

Definitely on the studio amp list and I have all of the parts needed.  Amps I'm going to keep are unfortunately at the bottom of the build list for now as building for sale is leading the way.

[bnwitt]

Well with several PV jobs coming in yesterday I didn't get much done on the amp but this morning I've gotten the board fully loaded and now for a bunch of soldering. Only (7) CC resistors.  Everything else is MF, CF or MO

[bnwitt]

Ok, here's the first sound sample.  A short example of the Tremolo.  Unfortunately there was a lot more chatting than playing and I hope to get the new owner back in the studio for some serious demos with a backing track.

https://www.dropbox.com/s/y112li8s9on11qk/Hoff%20DR%20Tremolo%201.mp3?dl=0

Barry

[billcreller]

Great looking work Barry !

[bnwitt]

Bill,
Thank you sir.  Good to hear from you.  I hope you are doing well.
Barry

[MFowler]

Nice job Barry the amp looks great and tremolo sounds good.


Hoffman style boards look so good but I get lost so fast regarding the circuit compared to Fender style, that's why I have never done a Hoffman board.


Mark

[bnwitt]

Nice job Barry the amp looks great and tremolo sounds good.

Hoffman style boards look so good but I get lost so fast regarding the circuit compared to Fender style, that's why I have never done a Hoffman board.
Mark

Thanks for kind words Mark.  I guess I'm just use to Hoffman layouts since I've done so many of them.  Even my own layouts end up like Doug's.  I like how he separates the preamp and power amp filtering and how quiet the amps are on idle.  Leo's 50's and 60s layouts are excellent as well though.  Every Fender amp I've built, converted or serviced ended up being very quiet on idle too.  I know another amp buddy from in here has said he doesn't like the flying wires of the Hoffman layouts.   That's not really a board layout issue though as you don't have to fly the wires you can run them down along the chassis and over to the controls like Fender did if you like.  To each his own I guess.  I am a methodical kind of guy and I always create my own layouts for each amp.  I didn't do that on the amp I just finished and hit a snag or two going from page to page of the different layouts gleaning the different variations of the AB763 I was using. 

On this current Hoffman Deluxe Reverb I've got my own customized layout so I can turn off my brain and just build.  You know, doing that "Asteroid" Layout years ago prepared me for just about anything.  Now that was a detailed project.  Remember that one? 

By the way, the first Hoffman DR amp made it into the San Diego players environment over the weekend and was well received.  It looks like I may have orders for more of them.  I might actually get some studio work out of it too.

[jojokeo]

Your amps look real good Barry and the documenting too

[purpletele]

Barry,

Your drawing is really nice!  That is a monster of an amp, very nice work.

[bnwitt]

Your amps look real good Barry and the documenting too

Barry,

Your drawing is really nice!  That is a monster of an amp, very nice work.

Thank you gentlemen.  I appreciate the kind words.  I've always lived by the Qasar and Paul Masson mottos.  Quality goes in before the name goes on and we will serve no wine before it's time.

I'm showing my age here.  

Purpletele, that Asteroid amplifier is a beast!  It was way too loud for me that's for sure.  So even though I originally built it for myself, it went to a player on the east coast somewhere.  I believe MFowler built one of them too but I'm not sure.  I do have a zip file with lots of documentation on the amp, parts schematic etc.  If anyone is interested PM me and I'll email it.

Barry

[MFowler]

With parts from Barry and his layout I built this Komet 60 in 2008 probably my 2nd build.


Sold it to a touring musician in California.

[bnwitt]

With parts from Barry and his layout I built this Komet 60 in 2008 probably my 2nd build.

And what a nice job you did my friend.  Wow!  That was a beauty.

Sold it to a touring musician in California.

You know every time I sell one of my creations it's like losing a baby.  And they seldom write home.  Once in blue moon I'll get an email or forum message from someone who has recently purchased one of my amps I sold years ago at an estate sale or from the initial buyer and it's like hearing from a long lost relative or something.  I can imagine how Leo Fender or Jim Marshall must have felt.  You get that post build pride all over again especially when the amp is still blowing minds after many years of service.  If it hadn't been for Doug Hoffman, Gerald Weber and other tube amp giants who were kind enough to share their knowledge (not to mention the gurus in here like Sluckey, PRR, HBP this list goes on) I would have never known the joys of tube amps.  I would have been stuck in the SS world with crappy tone.  I'll never forget my first Hoffman 5E3 coming to life on my kitchen table back in 96 or 97 and bringing my whole family running in saying Wow!  That sounds fantastic!  I had to agree and I've been doing this ever since.  Man I'm hooked on tube amps.

Barry

[bnwitt]

Back to the Hoffman DR, I just received some feedback on the amp from a San Diego guitarist who has been in many L.A. studios using the great vintage amps provided by the studios and he tells my customer it is the best amp he has ever played.  Hat's off to Doug Hoffman!  What a great design.

[bnwitt]

Ok, the chassis is about done, the front and rear plates came in yesterday and I've started on the cabinet.

[bnwitt]

You know just as an aside, one of the things I do not like on the original and the available clone BFDR chassis is the location of the fuse holder which is right in line with the V7 tube socket.  This position really restricts which holder can be used and makes some of the wiring challenging.  I've been making the rear plate longer on these amps and moving the fuse holder to the left in between sockets V7 and V8 which makes the tube socket wiring easier.   I also make the rear plate long enough to cover the ground switch hole which I don't use.

[bnwitt]

Well the chassis is completed and I'm working on finishing the combo cabinet.  There is a lot of woodworking involved in creating a good finger jointed DR cabinet.  I'm working on two DR and one PR cabinet and just finished an SR so I've got 4 cabinets ready for tolexing and grille cloth.  Boy is it hot and humid out here in SoCal lately.

[mresistor]

Very nice work Barry !  congrats on getting more orders too. I am still very appreciative of your assistance in building my HPR, my main amp.

[bnwitt]

Thank you sir.  How does that HPR sound these days?

[bnwitt]

I have updated the 4 page HDR file in my first post of this thread with some corrections.  Attached to this post is a 13x19 layout pdf

[purpletele]

I have updated the 4 page HDR file in my first post of this thread with some corrections.  Attached to this post is a 13x19 layout pdf

Good looking drawing, what program?  Did I ask you that already, sorry I can't locate the question as I look at the thread so it must not have taken place.

[TIMBO]

Awesome again!

[kagliostro]

My compliments


Nice job


Franco

[bnwitt]

I'm still using Visio 2003 for my layouts.