Anderton '64 reissue JTM145 - any info?

[Matec]

Hello
Here now are updated electric schemes JTM1, and "mine" HTM1-3.

Schema JTM1.

[img602]http://s26.postimg.org/8a30z0zk9/JTM1_R ... 6_2014.png[/img]

Schema HTM1-3

[img622]http://s26.postimg.org/4cfr9mcqx/HTM1_R ... 6_2014.png[/img]

They are basically the same, but Some components are in different positions.Some parts of the circuit JTM1 were not implemented in HTM1-3, without, however, affect the sound.

The components marked with "???" In schema JTM1 for some reason could not be properly checked their values​​. So there may be differences in their values ​​with the real ones.
If you have more questions, ask me.

Thank you.

Matec.

[Littlewyan]

In my Amp due to space limitations the Low Power switch is going next to the IEC Socket. Can anyone see this being a problem? I don't think much interference will be picked up by the switch, its going to be at least 1.5cm away from the IEC Socket. Or do you think I will get some nice buzzing?

I'm also mounting my Output Transformer next to the IEC Socket, its either there or between the PT and a Multi Cap Can! Anyone think this is a bad idea?

[Matec]

Littlewyan

Could you draw what you want to do?

The key Hi/Lo Power, should not make the uptake of "hum". The impedance of this circuit is very low. It would not matter, something that was captured there.

The worst are magnetic fields that can interfere, coming from the power transformer to the output transformer.

Cheers.

[Littlewyan]

Ok here is something I made up really quick (proper layout is drawn on paper). The circle on the left is the Cap Can. How its currently laid out shouldn't be an issue thinking about it. The OT is shielded from the IEC by the chassis and the PT is a toroidal so the magnetic field will be small and its far away anyway. I'll still do the listening test though to see what orientation is best for the OT.

[arjepsen]

Using the headphone trick, I usually end up with the least hum, when I sort of angle the ot a bit "away" from the pt.
Though sometimes (like my build of the htm) space restrictions make it harder to place it the way you want to.

[epis]

Hi guys,

first, I would like to thank all of you who contributed here, especially to Smokebreak for nice layout and of course to Matec

I was searching for a long time for good sound at low volume and finally found it
I have used spare parts from my parts bin, that's why some caps and resistors are paralleled (doubled), PT is from old 1966 German radio, 190V secondary, after finding out the price for small 20k Hammong OT - $50+, I've decided to roll my own. Iron was from the same radio with nice plastic spool, that made the job easier.
I didn't want to bother with complex calculus, just counted number of turns for 8 Ohm secondary - 120, and calculated the turns for 20k primary 3000 + 3000.
I used same wire thickness as original 41AWG.
It was easy to do it with my pickup winding rig.
I didn't use any insulation between the layers of wire, except some mylar foil between P and S coils. (If that worked for German engineers why shouldn't for me ? )
I did pay attention to make the layers nice and uniform.
So configuration of the coils was 1/2P + S + 1/2P, simple and worked great
I decided to use L pad for loudness attenuation, it worked fine, except at higher levels of attenuation, sound was muffled as everybody else experienced. Problem was solved by adding a bright cap 2.2 micro F across L pad. There was no more missing clarity, but there is still some more compression at 9:00 and below.
For a MID pot I had only 50K available, witch worked great, more mids and gain, less treble, guys who are complaining about extra treble content should try this value instead 25k.
Chassis size is 1 3/4 X 5 X 12"
Cabinet size is 6 1/2 X 6 1/2 X 15 "

How it sounds ? More or less as Smokebreak's amp, beautiful chimey cleans up to 11:00, after that crunchy overdrive and really more than enough gain when dimmed

That's it for now, keep on rocking

[IMG768]http://i1210.photobucket.com/albums/cc406/epis1/JTM1/IMG-20140622-00205_zpsc6d7a186.jpg[/img]
[IMG768]http://i1210.photobucket.com/albums/cc406/epis1/JTM1/IMG-20140622-00206_zps68cc12c9.jpg[/img]
[IMG682]http://i1210.photobucket.com/albums/cc406/epis1/JTM1/IMG_6513_zpscc911960.jpg[/img]
[IMG682]http://i1210.photobucket.com/albums/cc406/epis1/JTM1/IMG_6514_zps0fa98167.jpg[/img]
[IMG682]http://i1210.photobucket.com/albums/cc406/epis1/JTM1/IMG_6515_zps073a1a51.jpg[/img]
[IMG768]http://i1210.photobucket.com/albums/cc406/epis1/JTM1/IMG-20140622-00201_zpsf527bfe6.jpg[/img]

[IMG]http768]http://i1210.photobucket.com/albums/cc406/epis1/Ottawa-20110917-000342.jpg[/img]

[ampgeek]

Awesome Epis! Love the fact that you wound your own OT.
DIY at its very best!
Rock on,
Dave O.

[arjepsen]

Very cool!
I also have a few old radios i gutted, though i'd like to just use all the old parts, so its gonna have to be a single ended el84

[Littlewyan]

Looks smart as! Do like how you re used parts from an old radio, I want to do this one day it sounds like fun .

For my amp everyone I'm using a PT that gives 320V for the B+. This is obviously too high so to lower this I'm using a 2.2K Resistor with another filter capacitor before the OT Centre Tap. This should be fine shouldn't it? Shouldn't get any sag from the resistor as I've added another filter cap right?

[Smokebreak]

Whoa! Very very nice epis! Our amps could be brothers
I love how a tall can of beer has become the standard for a reference point.

Littlewyan I'm not sure with these little output tubes, if the increased current demand, when hit hard, won't cause unwanted mushy/flabby sag . Maybe the better solution would be the Zener trick between PT CT and ground, as that would provide a constant V drop.

Concerning your fusing, when I fired mine up, I only had 500mA fuses on hand, and used them. Once I got the schematic values, I stuck with 500mA mains, as my wall is 120V. I'm almost positive that when I put in the 125mA HT fuse, it blew, as I'm running 250mA now. I know that seems high, but that was my experience.

[Littlewyan]

The issue with the Zener Trick is if the zener blows then you'll have a floating HT. So its not very safe. The filtering in this amp is already very stiff, I worked out that you only really need a 16uF Reservoir Cap for this Amp, let alone 3 x 33uF along the whole HT chain! So I may not notice any difference. Have to wait and see. Its either that or 320V on the plates of the 12AU7, which I might get away with if I cool the bias down a bit as I think its already pretty hot.

Well 250mA will be fine as a mains fuse as the PT won't supply more than that. As for your B+ fuse was it definitely a slow blow?

[Smokebreak]

I used a fast for the HT, as I generally do, though I understand this is a topic of some debate

[Littlewyan]

A fast?

[Smokebreak]

A fast blow fuse for the B+

[Matec]

Hi!

I'm thrilled with the members of this forum. They got a scheme that did not know, and are making masterpieces. I also admire those who make DIY parts without major problems. epis, your amp is amazing, I hope it is to your liking. I agree with you, the layout of Smokebreak, has mounting the amplifier much simpler.

Thank you all.

Matec.