Newbie and Intimidated.

[dj_pga]

Let me start by saying I have built my first amplifier, a 5e3. Ever since I've finished it I have had problems with the volume. I have not posted before because all of the "regulations " about posting make it seem that if I have a problem it is my fault and my responsibility to fix it. I have rebuilt my amp twice with the same result, extremely low volume. I've even gone out and purchased an oscilloscope and signal generator to try to isolate the problem. At this point I am ready to purchase a kit with better instructions and abandon any Hoffman products at all. You must know I'm desperate if I found enough courage to post on this forum. Now I bet some "administrator" will respond by saying, "Dude, you posted in the wrong spot."

[sluckey]

Post voltages for all pins of all tubes. Hi rez pics help also.

[EL34]

welcome to the forum
Go to the main board for tech questions

[kagliostro]

Let me start by saying I have built my first amplifier, a 5e3. Ever since I've finished it I have had problems with the volume.

Ciao Dj_pga

May be you can find inspiration to solve your situation or the final problem is the same but reasons different but it is always useful to read

also what happen to other having problem similar to ours

Here someone that has a similar problem

http://el34world.com/Forum/index.php?topic=21995.0

Franco

[purpletele]

I've even gone out and purchased an oscilloscope and signal generator to try to isolate the problem. At this point I am ready to purchase a kit with better instructions and abandon any Hoffman products at all. You must know I'm desperate if I found enough courage to post on this forum. Now I bet some "administrator" will respond by saying, "Dude, you posted in the wrong spot."

DJ-pga,

I can certainly relate to your frustration, I had purchased a kit at one point as well and that was helpful, but in retrospect the Hoffman Kits and this forum are the safest place to learn and at least produce a decent amp.

I would say I am an intermediate amp builder and I have new issues and revelations every time I start a new project, which is the fun part for me.  I have had some very successful projects in the last two years and they are getting better and more sophisticated.

Here are my recommendations for success both immediately as well as in the future if you continue to build. 

1. Study the procedures for importing photos.  You have to be able to post photos well.  The folks that are on this forum actually like looking at photos of others work, and its fun for them to try to help.
2. Always post a schematic and layout that pertain to your issues.

    It's an effort to open documents that are posted, but these guys will open the documents and chime in if they think they spot something or have had a similar issue.

Based upon you comment, 'I even bought an Oscilliscope', indicates sufficient obsession to hang out here and learn how to use it correctly.  However I doubt your issues require a scope.

I'm interested to see how quickly your problems can be resolved.  Please post photos and schematics.

BV

[kagliostro]

To post in an easy way photo (of good quality)

upload it at http://imgur.com/ (it is free and didn't require a registration, more, they don't delete your images after a determined time)

when you have uploaded the imges, copy the image link and post here using the TAG <img> (the Mona LIsa icon under the B of <bolt> TAG)

you can see when you are writing a post

Ciao

Franco

[dj_pga]

First of all I must say that I am very appreciative of all the response. Tonight, after work, I will go home and register all of my tube readings, rectifier readings, and transformer readings. I will post them to see if anything stands out to people more experienced than me.
I've attached some of my previous work to show that I am not a total idiot; I do have some skills.

[dj_pga]

Here is a picture of my Hoffman Board.

DJ

[dj_pga]

Here is another picture of my board from a different angle.

DJ

[kagliostro]

OK, let me show you the difference

this is a 2400 dpi image (from your original at 432 dpi)



as you can see details are more easy to be seen

(you can't load a big image as attachment on the post, because of the dimensions, but you can post an image link and benefit of their details)

Franco

[purpletele]

I had an amp recently that had at least 3 Alpha Pots that needed to be replaced.  Each had a different issue, but it was a puzzling issue that I happened uncover with chopsticks and pressure.

 

[dj_pga]

Come to think of it, my pots do seem to suck. They are obviously brand new, but they are noisy and don't seem to be working linear.

DJ

[purpletele]

Come to think of it, my pots do seem to suck. They are obviously brand new, but they are noisy and don't seem to be working linear.

DJ

I love the Avatar.  Your board looks really nice, therefore I would assume that there are no issues with components and if it's up and running then I would be looking at the shielded wires and their respective grounds.   I would also be probing the Pots and moving wires.

I think I spent a full day chasing a lost signal and it turned out to be a shielded cable similar to the Blues Junior issue that was just solved.

If you are here, its too late, Better Call Saul!

[kagliostro]

In doubt swap momentary from shielded cable to simple wire

A friend, some time ago, after a long search discovered that the shield of a poor shielded cable was shorting the signal

Franco

[dj_pga]

I have often struggled with the "Hoffman" shielded input signal wiring. I have re-done the both the wiring twice. I believe I like the turret board wiring method better where there are the two 68k resistors.

The avatar is going to be my home/landing page for my golf instruction website. Thanks for the feedback.

[tubenit]

DJ,

Very glad to have you be a part of the amp building forum here.  It's a great place to learn and my experience is the knowledgeable guys could not be more gracious and patient with anyone who is new.

I've done perhaps 25+ different amp designs and numerically made at least 3 times that many mistakes.  I got them all fixed to the best of my memory. 

Sluckey has rescued me on more mistakes than anyone on the forum.  He is incredibly knowledgeable and will hang in there and walk you thru what you need to get it working right ................. IF you follow his direction.  He has helped me find the obvious that was staring me in the face and I was missing it .................. AND he has helped me find the odd and/or complex weird things that were problems.  HotBluePlates, DummyLoad, and about a dozen other guys have been very kind and patient in helping me with builds also.

Sluckey gave you some great advice 

Post voltages for all pins of all tubes.

   

That's where I would start also in my trouble shooting.  I hope you'll follow thru with his suggestion. 

We're glad you're here and were rooting for you and we'll help walk you thru this.   

With respect, Tubenit

[dj_pga]

Ok, I've taken my voltage readings and I'm embarrassed to post them! They are alll over the place.

V1 - 12YA7.       V2 - 12AX7.      V3 - 6V6.     V4 - 6V6
1. 79.3.                 96.7.             3.  341.         302.1
3.  1.145.              .898.             4.  246.2.       238
6.  73.2                 37.75.           6.  .01.            36.9
8.  1.173.              4.01.             8.  .01.            30

I'm obviously V3 -6 & 8 need to be re-wired. I don't get the other discrepancies, but I'll strip it down again if need be. 

[sluckey]

What voltages do you measure at the positive end of each of those three big filter caps? Show us some good pics of the inside of the amp. We need big pics, not postage stamp pics.

[dj_pga]

Not to worry everyone! While measuring my voltages a second time, my PT fried! I am the "Moosh!" I now have nothing to work on. I suck

[purpletele]

Not to worry everyone! While measuring my voltages a second time, my PT fried! I am the "Moosh!" I now have nothing to work on. I suck

What the heck?  Are you kidding.  Are you sure?  Check the fuse.

[dj_pga]

I wish I was. I was using a dummy load and everything. I just need to start again from scratch.  I can hit a stupid golf ball 300 yards, I can make quality guitars and basses, but this has been frustration beyond belief. When I rebuild, I will be asking how to test segments as I go along. 

[purpletele]

I wish I was. I was using a dummy load and everything. I just need to start again from scratch.  I can hit a stupid golf ball 300 yards, I can make quality guitars and basses, but this has been frustration beyond belief. When I rebuild, I will be asking how to test segments as I go along. 

Sorry to hear that.  How did you manage to take out the transformer?  Did you arc your test lead to the fuse lead?

Have a beer and start hunting for a new transformer

[tubenit]

How do you know you fried it?  Smoke, no voltages, did the fuse blow. .................      Please reply.


With respect,  Tubenit

[tubenit]

There is a great thread on "start up for amps" here:              http://el34world.com/Forum/index.php?topic=2376.0

There may be some useful information for you there.  Note Sluckey's excellent start up information on reply # 3.

With respect, Tubenit

[sluckey]

Do you know Christopher Robin?

[dj_pga]

Smoke billowed out of the lead port like a super volcano. I already purchased another Classic Tone last night. I good now, no more being Eyore.
It's off to work!

[tubenit]

I love your perserverance!  Bravo!  You'll get this up and running and have a great sounding amp.

 

With respect, Tubenit

[dj_pga]

Thank you for the encouragement. However, I was wondering if I should use a different board than the Hoffman for my 5E3? One thing I like about the other boards is that they don't use the shielded cable run with the 2 68k resistors basically hanging. I believe it is an easier wiring when the resistors are installed on the turret board.

Thoughts??????

[tubenit]

I personally have used and really like the Hoffman boards.  I've gotten some successful amps, tone and quietness from that design.

What you could consider is mounting a terminal strip next to the tube socket like they do on Dumblish amps, Matchless and many others.

With respect, Tubenit

[dj_pga]

I was thinking of doing something like that, but is there enough room???? I had to add a terminal strip for the 5Y3 because the pin was too small to handle the larger gauge wires (I can't remember the pin numbers off hand, but I thing it was around 8?).

[tubenit]

is there enough room

I have no idea what chassis you're using?  Nor have I seen a photo of the inside of your amp.  So, I am not able to answer that question. 

You tell me if you have room.   

with respect, Tubenit

[tubenit]

My Tweed BluezMeister uses a 20" x 6" x 2"  tweed style chassis.   AND  I have relay switching, clean channel, overdrive channel and active FX and a tube rectifier in that chassis.  Amp sounds great to me and is very quiet at idle.

So, I know it's possible to push the "crammage factor" on an amp and still have it sound good and be quiet.

With respect, Tubenit

[sluckey]

I would not replace the Hoffman board for that reason. It's really just as easy to put the 68K resistors on the jacks as it is to put them on the board. The later blackface amps put the resistors on the jacks but didn't use shielded cable. Hoffman has some good pics that show exactly how to wire the resistors on the jacks. And he has info about working with that RG-174 cable too. You do have to be careful with the cable because the insulation on the center conductor will melt very easily.

This is how I would do the input jacks on a narrow, crowded tweed chassis...

Temporarily mount the jacks on the outside of the chassis. Rotate them the same as Hoffman shows in the link below. Solder the resistors and jacks together. Now prepare the shielded cable and solder it to the jacks/resistors assembly. When done, remove the nuts and install the complete prewired jack assembly inside the chassis. Easy-peasy.

     http://el34world.com/charts/CommonHookups.htm

If you find the shielded cable impossible to use, just use a regular wire. There was no shielded cable in the original 5E3.

[sluckey]

If you have trouble fitting wires into a 5Y3 socket then you are using wire that is too big. There's no need to use any wire bigger than AWG 20 in that amp.

[purpletele]

Thank you for the encouragement. However, I was wondering if I should use a different board than the Hoffman for my 5E3? One thing I like about the other boards is that they don't use the shielded cable run with the 2 68k resistors basically hanging. I believe it is an easier wiring when the resistors are installed on the turret board.

Thoughts??????

Dj,

Your board looks pristine, I think you were down to a minor wiring issue for your muted sound, then you put your layup shot in the drink! I remember having thoughts similar to yours, now I don't want to do anything outside of this group's sphere of influence.

The Hoffman circuits are proven layouts, especially the 5e3.  I have learned recently that shielded wire is your friend if you treat it nicely, and the accuracy of your grounding is imperative to that part of the circuit. 

I don't think we have seen the board sitting in the chassis, the control wiring nor the tube sockets wiring. 

In my limited experience I would recommend posting the schematic and photos and then focus on the input and output wiring.  I have been stuck recently for days with a similar issue to find a minor ground issue.

Also, now that I think about it, I had one of two volume Pots on my 6 v 6 Plexi drop into a 1/2 power mode intermittently.  I mentioned that before, you have to consider that as a potential problem point.   

I cannot tell you how pleased I was to find that issue, make the change, and live with the positive results. 

For me, those tones of a solid signal is the nicest and most satisfying reward of these puzzles.

[dj_pga]

Sluckey,

The wire size was dictated by two of the three wires going to Pin 8 were from the PT and the OT. I felt like I didn't have a choice in the gauge of wire. Also, Hoffman recommends using #18 for the heater wires for the 6V6's and then scaling down to #20 for the pre-amp heaters. I followed the hook-up instructions as best as I could. I will re-do the shielded wires and input jacks again while waiting for my new Classic Tone PT to be delivered. I also worry about all of the grounding being done correctly - especially the wiring across all the pots.
What it does not really address is how to ground the shielding to the Pot ground Buss. I just soldered the shielding to the ground buss. I also assumed ALL grounding with the pots and ground buss was handled by the pots being attached to the chassis. Since I never got shocked, I figured it was the correct way to handle the ground buss.

[dj_pga]

Purple Tele,

Which types of Pots did you switch to? Can my Alpha pots be cleaned for better use??  How exactly did you solve your poor pot issues? Did you also run the ground buss wire as Hoffman recommends?

[purpletele]

Purple Tele,

Which types of Pots did you switch to? Can my Alpha pots be cleaned for better use??  How exactly did you solve your poor pot issues? Did you also run the ground buss wire as Hoffman recommends?

DJ,

I just replaced the pots with the same Alpha type from Doug's shop.  Since that incidence I have started taping the opening on the pots during the construction process.  Someone had mentioned that they might have dripped flux into the opening of one of their pots and I of course thought I might have done the same.

The amp was running really well then out of the blue it would drop out to half power.  I mentioned earlier, I have spent days looking for issues and that was one of those times.  I tried like mad to get it to fail under scrutiny, finally I caught it when it wasn't expecting it and replaced it.  That worked like a charm, then my treble would shut down power if I turned it all the way up. 

Once again I chased it until I decided to change the Pot and bingo.

I have not had any issues like that since, and I do implement a piece of tape over the opening's for insurance.

Also, before you tear anything else apart I would try spraying the pots with Deoxit.  I found that it either works very well or it will highlight a problem with a pot and its wipers.  Once I sprayed the pot treble pot then things worked well and then failed more precisely.  I changed the pot and it is solid.