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PostPosted: Wed Dec 29, 2010 10:25 am 
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Hello everyone. I picked up my kit from Stephen on Monday, and got the board and chassis populated last night. I was looking at the manual and I have a quick question. When installing the VRM module, there's the option of moving the 68K resistors to V1 and adding DC blocking caps. The info mentions to do this if the inputs are "scratchy". Does that refer to the volume pots being scratchy, or does the tone turn scratchy? I was just wondering if I should do that right away, or assemble as stock and mod if necessary? Also, if I do install this mod, it seems to me that you lose the Hi-Lo inputs and end up with two Hi inputs. Is this correct?

Thanks Stephen, for such a great kit. I can't wait to get this thing done and hear what it sounds like.

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PostPosted: Wed Dec 29, 2010 9:27 pm 
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It refers to the volume pots being scratchy. This is caused by a small amount of DC voltage that is present. That DC voltage is also present on your pickup's as well. So install those blocking caps if you want to get rid of the scratch and not have to worry about DC voltage on your pickups.

VRM won't change the tone of amp like your thinking. Just a very useful volume controlling device.

With VRM you still get the Hi and Lo inputs, that shouldn't change.

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PostPosted: Wed Dec 29, 2010 10:54 pm 
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Ok, one more question then. Is there any reason I couldn't run the DC blocking caps from the junction of the two 68K resistors instead of the jumpers listed, then move the 1M resistors to the socket of V1 as shown? Or would I be running into problems with RF interference or induced hum?

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PostPosted: Thu Dec 30, 2010 12:51 pm 
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Try it this way - just run the .1 uf blocking cap from the junction of the 68Ks direct to the tube pins.

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PostPosted: Thu Dec 30, 2010 5:33 pm 
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So I don't have to move the 1M resistor from the HI input? I'll give it a try and see what happens.

I'm hoping to finish the assemby of the amp today, and try a test run. Then I'll have to get started on the cab.

Thanks.

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PostPosted: Thu Dec 30, 2010 7:49 pm 
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Keep the 1M where they are. The resistors mount on the jacks pretty easily.

You don't want them after the 68K resistors. Then they are killing a tiny bit of gain while simultaneously doing their job of keeping the grid at a negative potential.

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PostPosted: Thu Dec 30, 2010 8:01 pm 
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kurtlives wrote:
You don't want them after the 68K resistors. Then they are killing a tiny bit of gain while simultaneously doing their job of keeping the grid at a negative potential.


I dint find putting them after the 68K affected tone noticeablty, but definitely easier to leave them on the jacks. That's what I did last one for Tristan's Tweed (i.e. just put the .1 after the 68Ks), and he really liked it.

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PostPosted: Fri Dec 31, 2010 3:21 am 
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Well, it's 2am, and it's built. The first power up made me nervous, but all went well checking voltages and such. But there's a buzz/hum/fizz. If I touch the chassis, 90% of the hum disappears, but some of it is still there. If I turn up vol 2 halfway, the amp get quiet. Either vol up all the way and there is noticable buzz/fizz. The tone affects the buzz, either cutting it or making it loud (the high end part of it). I chopsticked around inside, and the 0.047 cap on the tone pot makes noise when I tap it, as well as the leads to and from the tone pot. The coax is quiet, but the other connecting leads from vol pot to vol pot make some sound, But not as much as the tone leads at the tone pot.

Any ideas? I looked at the solder connections and they look good, and tapping them makes no read difference in the sound, you just can hear the tapping like someone knocking on a window.

As to the chassis issue, I checked all of the grounds and they are reading fine (all read 0.5 ohms or less), so I have no idea what is inducing the ground buzz. I moved around all of the heater wires with no change.

Any and/or all advice would be appreciated.

Oh yeah, the VRM does take the overall volume down, but the noise doesn't really disappear.

Oh, and just to make sure Stephen knows, I'm very happy and very excited about this amp. Can't wait to solve these couple of issues and get rocking. Thanks again for a great kit. The instruction manual was very clear and easy to follow. The kit goes together very well. Great job.

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PostPosted: Fri Dec 31, 2010 11:44 am 
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Check the power chord ground, make sure its there and solid. Go through the schem/layout and cross off each ground wire as you check it, your missing one somewhere.
0.5R is a bit high reading, I'd touch up some of those solders.

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PostPosted: Fri Dec 31, 2010 2:06 pm 
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I double checked the grounds, two were kind of iffy looking under better light, so I resoldered them. I tightened all of the ground point nuts (they were pretty tight, but I wanted to make sure. Powered her up, and now the only noise I get is when one of the vol pots is above 11. Stays quiet then some hiss appears when the pot goes above 10.5 or 11. I'm not that worried about that, cause I love sitting in that brown sound zone anyway.

I am so very glad I installed the VRM module. Man this thing is loud. The VRM really adds to the practicallity of the amp, but as well, as others have mentioned, at really low volumes, the VRM really adds an interesting flavour to the sound. Cool.

I remeasured my voltages, does anyone think some of the variance is a problem, or is everything within normal limits:

(recommended voltages in brackets)
V1 - pin1 133 (120), pin3 2.3 (2.0), pin6 120 (123), pin8 2.3 (2.0)
V2 - pin1 156 (167), pin3 1.8 (1.1), pin6 195 (157), pin8 51 (70.5)
V3 - pin3 396 (380), pin4 354 (338), pin8 22(22)
V4 - pin3 397 (382), pin4 354 (339), pin8 22(22)

Other than that, I love the tone. Trying the different inputs, I really like the differences. After playing for about 15 min, it seems my favorite right now is the bright lo input, but that can and will change.

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Last edited by doftya on Fri Dec 31, 2010 5:05 pm, edited 1 time in total.

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PostPosted: Fri Dec 31, 2010 2:53 pm 
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Congratulations. :happydance:
A little noise at 11 is acceptable! Now we know how important grounding is!

Voltges are close enough for a Tweed!

Post some pictures if you would. Especially the VRM installation.

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PostPosted: Fri Dec 31, 2010 2:57 pm 
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A few pics, the guitar is an Epiphone Special II, which is a les paul clone with simple electronics, like a Tele. The speaker is the TT Alnico 12".

Image

Image

You can just make out the DC blocking caps at the far end of the board acting as jumper from the 68K resistors to the inputs of V1. I mounted the VRM to the pot, and ran short jumpers to the MOSFET (they were around 1/2" long). I just need to get another chickenhead knob for the VRM pot. Any chance you could pop one in the mail for me? :roll:

Image

I love the way the tubes glow.

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PostPosted: Fri Dec 31, 2010 7:04 pm 
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Ok, I got some more pics, feel free to tell me I screwed up if need be.

Image

Image

Image

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Hopefully I havn't made too many mistakes, it's my first tube amp. I've build a couple of stompboxes, and one Ruby practise amp (uses a LM386 chip and runs on a 9V battery, 1/2W, but good enough for practising).

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PostPosted: Sun Jan 02, 2011 3:01 pm 
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Ok, one more question, I found a set of cab plans for the 5E3 (by Scott Cole), but it seems a bit big... or am I just imagining that. The hight seems good, but it seems to be very wide. I was wondering if building it more square would be a bad idea. Would the 5E3 fit into a cab similar to the ones I've seen the Tramp mounted into?

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PostPosted: Sun Jan 02, 2011 10:11 pm 
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what are the dimensions? the tweed cab is pretty compact. Dimensions: (H) 16'' x (W) 20'' x (D) 9 1/2'' Chassis Cut-Out 12 1/8

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PostPosted: Mon Jan 03, 2011 12:12 am 
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I was thinking of taking the 20" of width down closer to a square front. The height for a standard 5E3 cab is 16.5", so I was thinkng of building it either 16.5 square and 8.5" deep, or maybe bumping it up to 18" square. That was just my thought.

I've also been mulling over some ideas. Combo cab structure seems kinda set in stone. I was just wondering if changing things around would work or not. I don't have a strong attachment to trying to keep everything as per the original 5E3's. I'm not against it, but I'm also willing to do something completely custom as well. What about mounting the amp in the bottom of the cab? If the cab is on a stand making the knobs accessible, the speaker would be in a better position for listening to it. Maybe build it like a monitor wedge? What about having the amp mounted vertically?

I also have an idea for adding a built in mike stand for miking the amp... too many ideas maybe?

I've got a habit if making things much more complicated than they need to be.

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PostPosted: Tue Jan 04, 2011 11:04 am 
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This is your amp. Please do whatever it is you want and make it work for you. I love seeing people do original things.

Of course you couldn't sell it for as much afterwards. :wink: :roll:


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PostPosted: Tue Jan 04, 2011 6:59 pm 
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Why would I want to sell it?

If I was wanting to build an amp to sell, then yes, it would be built to spec. But this amp is for me... so... it'll be special. I spent some time maping the internals last night. It seems that anything smaller than 18" wide and you start running out of room between the magnet and the power tubes. So I think I'll be building one 18" square, and probably 8.5" deep. I'll post some pics when it's done.

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PostPosted: Wed Jan 05, 2011 6:47 pm 
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Yes, map out the Tone Tubby speaker magnet carefully.

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PostPosted: Tue Jan 11, 2011 10:01 pm 
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So the cab is getting closer to being done. Life got in the way for a bit. I've just got the edges to ease and do a good sanding, then the finish. I hope to get it done by or during the weekend. I'll post pics when I'm done.

Oh, I forgot to ask, or maybe I did and didn't get a response. Did anyone notice any blaring mistakes in the pics above? Were the pics of the VRM install good enough, or do you need some other angles? I know that some (most) of the leads are still a tad long, but they don't seem to mind at the moment.

Dave

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