Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: bnwitt on July 22, 2017, 08:10:48 pm

Title: Three Hoffman AB763s down, one more on the bench
Post by: bnwitt on July 22, 2017, 08:10:48 pm
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. :w2:
Barry
Title: Re: One Hoffman DR down, one to go
Post by: Joel on July 22, 2017, 08:41:08 pm
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.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 22, 2017, 09:54:10 pm
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.
Title: Re: One Hoffman DR down, one to go
Post by: sluckey on July 22, 2017, 11:22:44 pm
Looks good Barry. Did you use a pull switch on volume pot for the bright switch?
Title: Re: One Hoffman DR down, one to go
Post by: Joel on July 23, 2017, 06:15:31 am
Thanks Barry.
Title: Re: One Hoffman DR down, one to go
Post by: EL34 on July 23, 2017, 06:56:24 am
Looks great
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 23, 2017, 09:10:52 am
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
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 23, 2017, 09:12:35 am
Thanks Barry.
My Pleasure Joel

Looks great
Thank you Doug.  I appreciate the kind words.
Title: Re: One Hoffman DR down, one to go
Post by: Ritchie200 on July 23, 2017, 11:31:27 am
Barry,

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

Jim
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 23, 2017, 11:59:02 am
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
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 23, 2017, 04:01:19 pm
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
Title: Re: One Hoffman DR down, one to go
Post by: sluckey on July 23, 2017, 04:42:46 pm
I bet you're back up to speed now. Things get rusty when you stay away too long. Happens to all of us.  :icon_biggrin:
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 23, 2017, 06:32:06 pm
Steve,
No doubt there was some rust on my chopsticks :laugh:   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.
Title: Re: One Hoffman DR down, one to go
Post by: shooter on July 23, 2017, 07:46:17 pm
Quote
I found out that the way to make a million dollars in the amp business was to start with two million
:l2:
with optimism like that you're bound to succeed, if you have money to burn, take up painting :icon_biggrin:
Title: Re: One Hoffman DR down, one to go
Post by: PRR on July 23, 2017, 08:14:59 pm
> 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.
Title: Re: One Hoffman DR down, one to go
Post by: Joel on July 23, 2017, 08:20:40 pm
I was just admiring the power board with integral lamp limiter.  Very nice!  I think I'll have to steal that idea.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 23, 2017, 11:09:29 pm
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 (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
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 24, 2017, 12:19:28 pm
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
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 24, 2017, 02:30:57 pm
now for the bus wiring of the board on my swiss cheese busing board.  Lots of boards have been bused on it.
Title: Re: One Hoffman DR down, one to go
Post by: Ed_Chambley on July 24, 2017, 03:27:15 pm
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!
Title: Re: One Hoffman DR down, one to go
Post by: sluckey on July 24, 2017, 04:39:06 pm
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!  :icon_biggrin:
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 24, 2017, 06:25:44 pm
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!  :icon_biggrin:
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
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 24, 2017, 08:30:00 pm
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 :laugh:
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 27, 2017, 08:05:45 am
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
Title: Re: One Hoffman DR down, one to go
Post by: Ed_Chambley on July 27, 2017, 08:21:14 am
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. :rolleyes:


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.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 27, 2017, 10:29:17 am
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. :rolleyes:  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. :w2:  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.
Title: Re: One Hoffman DR down, one to go
Post by: Ed_Chambley on July 27, 2017, 12:25:18 pm
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!!!
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 27, 2017, 02:42:10 pm
...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.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 29, 2017, 03:22:47 pm
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
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 30, 2017, 03:01:35 pm
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 (https://www.dropbox.com/s/y112li8s9on11qk/Hoff%20DR%20Tremolo%201.mp3?dl=0)

Barry
Title: Re: One Hoffman DR down, one to go
Post by: billcreller on July 30, 2017, 10:46:38 pm
Great looking work Barry !
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on July 31, 2017, 07:43:53 am
Bill,
Thank you sir.  Good to hear from you.  I hope you are doing well.
Barry
Title: Re: One Hoffman DR down, one to go
Post by: MFowler on August 01, 2017, 08:59:31 am
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
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 01, 2017, 12:40:01 pm
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. :icon_biggrin:
Title: Re: One Hoffman DR down, one to go
Post by: jojokeo on August 01, 2017, 04:06:03 pm
Your amps look real good Barry and the documenting too
Title: Re: One Hoffman DR down, one to go
Post by: purpletele on August 01, 2017, 07:10:29 pm
Barry,

Your drawing is really nice!  That is a monster of an amp, very nice work.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 02, 2017, 08:17:35 am
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. :l2:

I'm showing my age here. :laugh: 

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
Title: Re: One Hoffman DR down, one to go
Post by: MFowler on August 02, 2017, 09:21:31 am
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.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 02, 2017, 09:33:51 am
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
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 02, 2017, 10:06:27 am
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.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 04, 2017, 07:30:33 am
Ok, the chassis is about done, the front and rear plates came in yesterday and I've started on the cabinet.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 04, 2017, 08:19:14 am
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.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 12, 2017, 07:14:08 pm
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.
Title: Re: One Hoffman DR down, one to go
Post by: mresistor on August 13, 2017, 07:52:23 am
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.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 13, 2017, 08:11:33 am
Thank you sir.  How does that HPR sound these days?
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 16, 2017, 09:15:06 am
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
Title: Re: One Hoffman DR down, one to go
Post by: purpletele on August 17, 2017, 12:52:24 am
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.
Title: Re: One Hoffman DR down, one to go
Post by: TIMBO on August 17, 2017, 04:01:12 am
Awesome again!
Title: Re: One Hoffman DR down, one to go
Post by: kagliostro on August 17, 2017, 05:07:13 am

My compliments


Nice job :thumbsup:


Franco
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 17, 2017, 08:04:24 am
I'm still using Visio 2003 for my layouts.
Title: Re: One Hoffman DR down, one to go
Post by: MFowler on August 17, 2017, 08:50:45 am
Nice job on that layout as usual.  Does Windows 10 support Visio 2003?


Mark
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 17, 2017, 11:04:27 am
You can run it as long as you don't have a later version of Microsoft office products installed on the computer.  Also, when you shut it down, it has a little glitch where it tries to re-launch and you have to close the pop up.  I haven't tried compatibility mode with it which might fix that.  I do most of my work on my Windows 7 machine and I'm still using my 2003 Microsoft Office programs on that computer instead of later versions.  My Studio computer and my second office computer are Windows 10 so I occasionally run it on those machines and it works.  I just don't like Ribbon user interfaces as it's too hard to find your tools going from tab to tab.  With the 2003 Office products it's a lot easier to put your most frequently used tools on the main page so you don't have to jump around getting at them.
Title: Re: One Hoffman DR down, one to go
Post by: purpletele on August 17, 2017, 11:39:29 am
If anyone is interested, I think the pricing is still available for Visio 2016 @ $170, which would include a remote installation from a tech.

Windows 10 and Visio 1016 originally had issues and people abandoned it.  the issues are fixed and the software is much less expensive.

Contact me if interested.

otis8@sbcglobal.net
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 17, 2017, 03:48:01 pm
You know I started using Visio Pro in 1995 long before Microsoft bought it from the two guys who created it.  I used it for floor plans when I was a regional engineer with Marriott.  I absolutely loved the program for drawing scaled plans.  Then Microsoft bought it and the two guys got rich.  Microsoft's first update had no new features except copy protection to prevent one from using it on more than one PC and the price went from $199 to $499.  Each subsequent update was less useful than before as they slowly changed it from a CAD like program to a charting program for IT folks.  It is just a shell of it's former self in today's version.  I just checked my 2003 version in compatibility mode in Windows 10 and it works without the shutdown glitch I mentioned before.  An un-opened version of Visio 2003 Professional can be purchased for around $40 on the bay if all you want to do is draw amps, but as I said, you can't have it installed at the same time as other Microsoft Office programs later than 2003.  And of course I'm sure that was done on purpose by Microsoft.
Title: Re: One Hoffman DR down, one to go
Post by: kagliostro on August 18, 2017, 09:29:59 am
I use a 2007 version of Visio (on Windows 7 64bit)

an used version can be find on the cheap on e-bay

Franco
Title: Re: One Hoffman DR down, one to go
Post by: purpletele on August 18, 2017, 10:39:27 am
You know I started using Visio Pro in 1995 long before Microsoft bought it from the two guys who created it.  I used it for floor plans when I was a regional engineer with Marriott.  I absolutely loved the program for drawing scaled plans.  Then Microsoft bought it and the two guys got rich.  Microsoft's first update had no new features except copy protection to prevent one from using it on more than one PC and the price went from $199 to $499.  Each subsequent update was less useful than before as they slowly changed it from a CAD like program to a charting program for IT folks.  It is just a shell of it's former self in today's version.  I just checked my 2003 version in compatibility mode in Windows 10 and it works without the shutdown glitch I mentioned before.  An un-opened version of Visio 2003 Professional can be purchased for around $40 on the bay if all you want to do is draw amps, but as I said, you can't have it installed at the same time as other Microsoft Office programs later than 2003.  And of course I'm sure that was done on purpose by Microsoft.

Barry,

Can I pilfer your tube sockets from Visio?

I like those with the numbering.

otis8@sbcglobal.net
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 18, 2017, 12:40:32 pm
Barry,
Can I pilfer your tube sockets from Visio?
I like those with the numbering.

otis8@sbcglobal.net

Sent to your email sir.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 19, 2017, 02:29:45 pm
Well I'm still waiting for some more 18GA green wire to finish HDR #2 so I've started on #3 while I wait.  In the mean time here is a photo of #2's chassis.  I took a Fender twist and tuck tack instead of all of the flying wires on this one.  When I get the heaters connected we'll see how quiet it is.  Also, there is only (1) CC resistor in this one and that is the 3.3megohm reverb mix resistor.  Can't seem to find that value in MF.  I know the OT wires are long but I'm just waiting to crank it up and make sure I don't have to change their phase before I shorten them.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 20, 2017, 12:45:12 pm
Cabinet #2 is finished.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 22, 2017, 06:01:34 pm
Well I'm still waiting on heater wire for HDR #2 so I'm working on the cabinet for #3.  Sometimes it takes a lot of clamps to overcome the cupping in pine boards.  Sheesh!  After I am done with HDR #3 I'm moving on to Sluckey's AC 15 amp build.  I'm going to do a 1x12 combo and I've got some Vox black grill cloth (might not use it) but I'm trying to decide what color and type of Tolex to use.  Maybe I'll go with the vintage look or maybe the cream look.  What does everyone think.  Now that I have an Incra I-box finger jointed cabinets are a breeze so anything goes.  I'm interested in the opinions of all of you amp aholics out there.  I'll probably make a couple of these for sale as well as one for my studio so I need to know what look excites.
Title: Re: One Hoffman DR down, one to go
Post by: mresistor on August 23, 2017, 05:24:54 pm
Thank you sir.  How does that HPR sound these days?


Sounds great..  I have always had JJ's in it. It's not a normal HPR  has an oversized/ove spec'd Allen PT and a Deluxe OT. I built a HDR though, marshall style head, that is working it's way to being my #1.
Next up is a HSR (Super) - probably also a head.


Sorry I can't give you a fave on the Vox - they both look really nice.

Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 27, 2017, 08:37:58 am
Ok, I finally received the 18ga heater wire and have completed the HDR #2 amplifier which only has the (1) 3.3megohm carbon composition resistor in the amp.  All other resistors are mostly 1 watt metal film with (2) 1 watt carbon film resistors and (1) 1/2 watt carbon film resistor (as I didn't have MF for those values) and 1 watt or 3 watt metal oxide power resistors (plate and B+ dropping resistors).

This amp is dead quiet with the volume controls at 10.  Absolutely no resistor hiss or other noise present.  HDR #1 which was mostly CC resistors had some hiss at full volume.  This is a huge difference.  Now I have to get some players to compare the two amps side by side for tone.  I hope they both sound great so I can move away from CCs altogether.  We'll see. 

You definitely want to shield the underside of the cabinets on these amps as they will pickup spurious signals.  While taking a photo with my phone of the chassis in my amp cradle with the amp turned on in burn in mode, I could inject the Wi-Fi Bluetooth phone signal into the amplifier from about 1 foot away.
Title: Re: One Hoffman DR down, one to go
Post by: CraigB on August 27, 2017, 07:28:33 pm
Dang, that is one fine looking gut shot!  You're a rockstar man.  Beautiful work! Any top chassis shot?
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on August 27, 2017, 08:51:55 pm
CraigB,
Thank you sir.  Yes, here is a top chassis shot.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on September 02, 2017, 02:22:40 pm
Just and FYi, I've updated both files in this thread.  The 4 page set and the 11x17 layout have both been updated to match the current Hoffman board layout which is a little tighter than the original board from long ago.  Trying to get HDR#3 finished and then it's on to the Sluckey AC15.  I am supposed to get some recording done on these amps next Saturday and I'll share those when I get them including some CC amp to MF amp comparisons which will show the major difference in noise at idle.
Title: Re: One Hoffman DR down, one to go
Post by: bnwitt on September 09, 2017, 03:36:28 pm
Ok, I spent 4 hours this morning with 2 local guitar players playing and recording HDR #1 and #2 side by side.  You may remember that #1 was mostly CC resistors and flying wires while #2 is metal film resistors with only 1 C.C. and twisted Fender style wires.  #1 has been in the possession of it's owner for several weeks now and to my surprise, it is now very quiet on idle.  The hiss which was present at delivery when the amp was dimmed is gone.  I assume this is due to the CC resistors drying out under power.  #2 is just as quiet as #1 but even better news is the tone with M.F. resistors is just as sweet.  Both resistor types and lead dress methods produce a great sounding quiet on idle amplifier.  Sweet!  So all subsequent HDR amps will use M.F. resistors to avoid value drift over time and twisted control wiring to minimize wire flop during amp transport.


Over the next few days I will pull out some sound bites from the session to share.
Title: Re: Two Hoffman DRs down, one to go
Post by: purpletele on September 09, 2017, 05:02:06 pm
Good report,

I am ordering my resistors soon for my Deluxe.
Title: Re: Two Hoffman DRs down, one to go
Post by: bnwitt on September 10, 2017, 11:13:56 am
Have fun building it purpletele.  They are great amps.
Title: Re: Two Hoffman DRs down, one to go
Post by: bnwitt on September 12, 2017, 09:45:35 am
Ok, I've got lots of clips to wade through on this recording session but here is the first one.  HDR #1 on the left and HDR #2 on the right.  Both amps were recorded with a separate SM57 on the grilles raw into an Art Digital Gold 2 channel preamp and then into a Tascam DP-01.  No compression or any external effects were used.  HDR#2 had an American Deluxe Strat with vintage noiseless pickups and S1 switch plugged into the Tremolo channel.  HDR #1 was a Mexican strat straight into the Tremolo channel after a looper pedal that was used occasionally during the session to add background rhythm parts.

https://www.dropbox.com/s/lwezh5rd7z71g28/HDR%201%262%20clip%201.mp3?dl=0 (https://www.dropbox.com/s/lwezh5rd7z71g28/HDR%201%262%20clip%201.mp3?dl=0)

Barry

ok second clip:

https://www.dropbox.com/s/r5jqzufp2hnx3ig/HDR%201%262%20clip%202.mp3?dl=0 (https://www.dropbox.com/s/r5jqzufp2hnx3ig/HDR%201%262%20clip%202.mp3?dl=0)

A bit of noodling going on here
Title: Re: Two Hoffman DRs down, one to go
Post by: bnwitt on September 12, 2017, 11:07:40 am
And for a while at least, here is the last loaded HDR turret board.  I should finish the chassis today or tomorrow.  Tolexing the cabinet is the last thing to do on this third HDR.  And then it's on to the AC15 unless I get a commitment from a potential buyer for a 1987 Plexi or 2204 JCM800.

Man I love the smell of electronics in the morning :icon_biggrin:
Title: Re: Two Hoffman DRs down, one to go
Post by: bnwitt on December 31, 2017, 12:17:09 pm
Just when I say "done"  another Hoffman AB763/6G16 Deluxe style amp on the bench.  Hopefully it will be done sometime this week.  I'm taking my sweet time on this one though as I don't want the silly mistakes on it like I had on the rush job Super Reverb version I just completed.
Title: Re: Two Hoffman DRs down, one to go
Post by: purpletele on December 31, 2017, 02:15:23 pm
Ok, I've got lots of clips to wade through on this recording session but here is the first one.  HDR #1 on the left and HDR #2 on the right.  Both amps were recorded with a separate SM57 on the grilles raw into an Art Digital Gold 2 channel preamp and then into a Tascam DP-01.  No compression or any external effects were used.  HDR#2 had an American Deluxe Strat with vintage noiseless pickups and S1 switch plugged into the Tremolo channel.  HDR #1 was a Mexican strat straight into the Tremolo channel after a looper pedal that was used occasionally during the session to add background rhythm parts.

https://www.dropbox.com/s/lwezh5rd7z71g28/HDR%201%262%20clip%201.mp3?dl=0 (https://www.dropbox.com/s/lwezh5rd7z71g28/HDR%201%262%20clip%201.mp3?dl=0)

Barry

ok second clip:

https://www.dropbox.com/s/r5jqzufp2hnx3ig/HDR%201%262%20clip%202.mp3?dl=0 (https://www.dropbox.com/s/r5jqzufp2hnx3ig/HDR%201%262%20clip%202.mp3?dl=0)

A bit of noodling going on here



Nice clips Barry.  Your amps sound great and the guitar work is very nice.
Title: Re: Three Hoffman DRs down, one more on the bench
Post by: bnwitt on December 31, 2017, 04:44:41 pm
Thanks Purpletele but it wasn't me playing.  Those are my amps but it's one of my customers and his brother playing them.  It was a couple of strats into two of my Duke 65 Hoffman Deluxe Reverbs.  They are great sounding amps for sure.
Title: Re: Three Hoffman AB763s down, one more on the bench
Post by: bnwitt on January 01, 2018, 03:20:25 pm
Ok, I have updated the 13x19 layout drawing pdf and the 4 page build information drawing pdf as well.  The files in the previous posts are updated and here they are as well.  These versions show the Red LED in the Tremolo section of the circuit.  I will update the voltage chart and the Schematic shortly.
Steve, take a look at the led polarity in the drawings if you would and make sure it is correct.  :icon_biggrin:
Title: Re: Three Hoffman AB763s down, one more on the bench
Post by: sluckey on January 01, 2018, 04:08:53 pm
I'm surprised you didn't put the LED on the front panel. Was that just too geeky for you?   :icon_biggrin:
Title: Re: Three Hoffman AB763s down, one more on the bench
Post by: bnwitt on January 01, 2018, 05:29:12 pm
Look closely at the faceplate page in the 4 page file :l2: Didn't put it on this one but probably will on the next one
Title: Re: Three Hoffman AB763s down, one more on the bench
Post by: bnwitt on January 02, 2018, 09:25:15 am
I just finished wiring the 4th AB763/6G15 Hoffman amp chassis.  Attached are a couple of photos of the finished chassis.  Now I have to run through the entire amp and make sure everything is wired correctly.  I took my time on this one so hopefully all is well. :grin:  Once I test it and all is good I will complete the voltage chart and annotated schematic to upload.  Then it's on to tolexing the cabinet and putting grill cloth on the baffle board.  This HDR has a pull on push off bright switch on both channels and the 0.47uf capacitor, red LED and 220 ohm resistor (instead of the original 470K ohm resistor) in the tremolo circuit to increase intensity.  I've got a couple of Marshall 18 watts next on the list.
Title: Re: Three Hoffman AB763s down, one more on the bench
Post by: bnwitt on January 02, 2018, 09:25:54 am
The finished chassis