Using the pre-drilled HA 5F6-A board

[leonc]

I'm planning to build an amp which is pretty much a 5F6-A bassman. One of the things I'm contemplating doing is using the pre-drilled board for sale on the HA site. I've been trying to compare it to the original Fender layout and I'm just not following how it relates to the original layout in the Fender schematic/layout.

If you've used this board to build this model can you post a photo (or email me if you prefer) of your completed board? Thanks!

[sluckey]

When you say "HA site" are you referring to Hoffman Amplifiers site? If so, don't try to compare the Hoffman layout to the original Fender layout.

[leonc]

When you say "HA site" are you referring to Hoffman Amplifiers site? If so, don't try to compare the Hoffman layout to the original Fender layout.

Yes, that's what I'm getting at...it doesn't appear to match up...and that begs the question--is the layout for that board documented somewhere?

[John]

http://www.el34world.com/schematics.htm  <--- layout

http://www.el34world.com/Hoffman/5f6aparts.htm  <--- parts listing

http://www.el34world.com/charts/instruc_reissuecaps.htm  <--- more info

http://www.el34world.com/schematics.htm  <--- information page

That should get you started. Cheers!

[sluckey]

Yes, that's what I'm getting at...it doesn't appear to match up...and that begs the question--is the layout for that board documented somewhere?

Compare the Hoffman layout to the original Fender schematic. I think you'll see they are the same.

[sluckey]

Are you the same Leon that was hanging out on the Yahoo Valco/Magnatone group back in 2008?

[tubenit]

Are you the same Leon that was hanging out on the Yahoo Valco/Magnatone group back in 2008?

Are you this guy?  IF so, I appreciate the help you gave me some months ago about a particular amp design that you looked over. 

https://www.youtube.com/watch?feature=player_embedded&v=aEhWqvyaiuE

This is one of my favorite videos and amp tones. And it's an amp that I hope to eventually build.

With respect, Tubenit

[leonc]

Are you the same Leon that was hanging out on the Yahoo Valco/Magnatone group back in 2008?

Yup.

Are you the same Leon that was hanging out on the Yahoo Valco/Magnatone group back in 2008?

Are you this guy?  IF so, I appreciate the help you gave me some months ago about a particular amp design that you looked over. 

https://www.youtube.com/watch?feature=player_embedded&v=aEhWqvyaiuE

This is one of my favorite videos and amp tones. And it's an amp that I hope to eventually build.

With respect, Tubenit

Guilty as charged.

[leonc]

When you say "HA site" are you referring to Hoffman Amplifiers site? If so, don't try to compare the Hoffman layout to the original Fender layout.

Compare the Hoffman layout to the original Fender schematic. I think you'll see they are the same.

Sorry sluckey...I'm having a hard time reconciling your two posts. I still don't see how the photo of the board corresponds to the original Fender layout in the original Fender schematic...but no worries...I've already decided to do it a little differently than the Fender layout; I'm going to try putting the filter caps closer to where their used so it's easier to ground them with other components from those parts of the circuit...thus rendering my original question moot. But I appreciate your replies and help.

[sluckey]

Sorry sluckey...I'm having a hard time reconciling your two posts. I still don't see how the photo of the board corresponds to the original Fender layout in the original Fender schematic...but no worries...I've already decided to do it a little differently than the Fender layout; I'm going to try putting the filter caps closer to where their used so it's easier to ground them with other components from those parts of the circuit...thus rendering my original question moot. But I appreciate your replies and help.

It doesn't even resemble the original Fender LAYOUT. But Hoffman's 5F6A layout does follow the original Fender SCHEMATIC. I'm using two key words here. One is LAYOUT and the other is SCHEMATIC. Layout does not mean schematic.

Doug's layout, even though quite different from the Fender layout, is very logical. It uses a proven quiet grounding scheme that allows you to put the filter caps right adjacent to the circuit they are associated with. I think that since you want to deviate from the original layout you should consider Doug's layout. Spend a little time studying it and ask questions here. There has been a lot of amps built right on this forum using Doug's 5F6A board. That means a lot of experience here that will willing share info with you.

And if you decide to still do a different layout (a lot of us do), please stick around and share your project with us. We're kinda addicted to that stuff and will be very interested in your project.

On a different note... I restored a Maggie M10A back in '08. That's when I ran across your name. I hung around on the Valco/Maggie board for a while during that project and posted several messages. I think you even replied to some. A year or so later I built a stand-alone pitch shifting vibrato unit based on the old Hammond organ vibrato circuit. I quite innocently called it a Warbler. That didn't set too well with one guy and I understood. I assured him that my project was a one of a kind hobby project and that I was not going to be in competition with him.

Anyhow, welcome to the forum and stick around.

[leonc]

Yeah I noted that you said schematic in one and layout in the other...but the two were typically part of the same document. I'm hardly "Mr Experience" by I can't recall seeing a layout that attempted to closely conform to a schematic per se so I wasn't 100% sure what you were saying. Be that as it may, I don't doubt that the HA design will do the job very well. But ultimately, drawing stuff out and building it myself is half the fun--well sometimes at least, LOL--so I think I'll just go my own route here.

As for "warbler" (Gary from Juke Amps)...he can be pretty crusty, yes? LOL. I've gotten along with him well over the years and found him to be quite knowledgeable of those old Maggie circuits (and a lot of other amps too). But I've seen him really "get into it" with lots of folks too.

[tubenit]

Doug's layout, even though quite different from the Fender layout, is very logical. It uses a proven quiet grounding scheme that allows you to put the filter caps right adjacent to the circuit they are associated with. I think that since you want to deviate from the original layout you should consider Doug's layout.

+1  Doug's design is super quiet and very logically laid and easy to mod or work on.

LeonC,  glad to have you on board here.  I think your video with 1688TN2 is in the top handful of amp tones that I've ever heard.  Remarkable tone and excellent guitar work on your part.  I've probably watched that video over a dozen times.  Your other videos are also
superb.  I appreciate your sharing them.

IF you have ExpressSCH (free download) and want a couple of other 5F6-A schematics and layouts including one with reverb which are easily editable, you can look at these schematics and layouts:  http://www.el34world.com/Forum/index.php?topic=571.0

Please share what you eventually come up with, I'll look forward to seeing it!

with respect,  Jeff   aka Tubenit

[leonc]

Thanks will check it out. Yes I do have Express on one of my other computers...I should load it up on this one.

[HotBluePlates]

Yeah I noted that you said schematic in one and layout in the other...but the two were typically part of the same document. I'm hardly "Mr Experience" by I can't recall seeing a layout that attempted to closely conform to a schematic per se ...

Forget that you may see the two together for a moment.

A schematic is a document showing the logical arrangement of electronic components, with a focus on how parts are interconnected. It may bear no resemblance to the physical product.

A layout is a document showing the physical arrangement of electronic components, with a focus on spatial relationships between parts. It may show interconnections well, or it may make connections difficult to trace.

Generally, one looks at the schematic to see how the circuit is arranged (especially to sort out probably malfunctioning parts), then one looks to the layout to find where in the chassis the suspect part can be found. Sams went to the Nth-degree with layouts in one sense by using an actual photo of the chassis.

When Sluckey says don't compare layouts, he means tracing one to the other is needlessly hard. But if you had paper copies of the Hoffman layout and Fender schematic, and use a colored marker to check parts off, you'll find they're all there.

[leonc]

So I finished (for now, LOL) my 5F6-A head. I built it with a spare chassis I've had sitting here. It was a bit on the small side but it worked out fine, after making a few adjustments. I've used my own layout--which while close to the original in many ways, still has some significant differences. First, I built this has a head with no intent of using it with the stock speaker or jack configuration; I used Magnetic Components' multi-tap OT and added a rotary switch for 4-8-16 ohm load. Second...I got no need for a ground-reversal switch...and I needed the extra space, so I tossed that and moved the fuse to the bottom side of the chassis. Next, I mounted the filter caps on the main board. They're grounded with the sections they serve. I've got the input resistors wired directly to grids on V1 and leads from the jacks down to them. I also added a trim pot to adjust the bias.

After playing it fixed bias for a while, I decided to add a switch so I could take it cathode-biased as well. This turned out to be more straight-forward than I thought it would be; I've got it mounted between the rectifier and first power tube. I made this video before I added the cathode/fixed bias switch so this is all fixed bias. There are some photos in the video. (I'm playing it through a 2x10 open back pine cab I made last summer; got a pair of Celestion gold Alnico 10s in it).

'59 Bassman 5F6A Style Amp Demo by Leon C

[tubenit]

Leon,

THANKS for sharing the results of your build.  It turned out great!  Nice tone to it. I like both guitars with it but particularly liked the strat with it.  Very talented playing also.

Nice tone & great looking build!  Bravo.

With respect, Tubenit

[leonc]

Thanks for the kind words Tubeinit. Yeah, I'm diggin it with all my guitars so far. Tele sounds great through this circuit as well. I'm going to do another clip with it in cathode-bias mode. Actually, what I'll do is play the same riffs/chords with fixed than cathode-biased. Some of the diff will probably come through on the video, but really, the difference is in "feel/responsiveness" more than in tone per se.

[tubenit]

Leon posted another sound clip of this great amp.  Nice jazzy/blues playing at the start of this!

5F6-A Style Amp demo - Fixed vs. Cathode Bias by Leon C

With respect, Tubenit

[leonc]

Thanks Tubenit - I'm playing (or botching, I should say, LOL) Kenny Burrel's classic, Midnight Blue in the beginning of the clip. That whole record is just fantastic!!