First Express clone ready :o)

mat · Post by **mat** » Mon Oct 30, 2006 8:15 pm

Hello,

I got this ready a couple of weeks ago. It seemed first too tight and uncontrolled. I thought I should play it for while it to open more. I took the master volume circuit (the simple one) out of it and I think I like it better that way. I also changed the V1 and V2 tubes from Tung-sols to JJ's - not over tight anymore. Power tubes are JJ EL34's.

I'm as surprised as everyone how loud this thing gets

In no way I can record an overdriven sound sample in my home

I have to take it to band rehersals but must fiqure out first with what eguipment I'm going to record the amp...

The power trannie is from My homeland and the OT is a Hammond 1650H. Not optimal- I know- but one day I will have enough money to order one from Moose or Ceriatone.

The caps are OD 715P series - I know I know, not perhaps the best choice

Smaller caps are silver micas.

The filtercaps are 3 x JJ 47uF's and 3 x F+T 22uF's.

Here is a picture of the guts with the now removed MV. My friend made the chassis for the cabinet that was earlier on a different amp I made.

[img:800:600]http://www.pichotel.com/pic/16028B31e/74930.jpg[/img]

I measured the voltages today and I would be greatful if someone more skilled would give me an analysis of them (V2 plate seems waaay too high):

B+1 = 410V
B+2 = 399V (1k 25w)
B+3 = 313V (18k 3w)
B+4 = 292V (10k 3w)
B+5 = 274V (10k 3w)

Bias: -34.2VDC grid to ground

V1a 197V, 2.05V
V1b 173.3V, 1.5V

V2a 259V, 3.08V (with the Tung-sol the plate gave 266V !)

PI pins:
1 193V
2 26.5V
3 39.5V
6 197.8V
7 25.2V
8 39.5V

Power Tube 1:
1 0.03V
3 408V
4 394V
5 -34.4V
6 399V
8 0.03V

Power Tube 2:
1 0.029V
3 409V
4 396V
5 -34.3V
6 399V
8 0.029V

I've tried my clone with 2x12'' red white and blues. They are great for my Dumble clone but I will try the cab I have at band reherseal room that has one 12''greenback and one 10''eminence something.

I'm going to build a Les Paul copy with P90's in it. Do You think they are good choises with Express ?

Big thanks to Nik for his layout that made it very easy to put this together

Thanks,

mat · Post by **mat** » Tue Oct 31, 2006 9:30 am

One close up photo:

[img

1200]http://www.pichotel.com/pic/16028B31e/84118.jpg[/img]

btw. the V2 plate resistor measures 99.6K in circuit so I think it is right.

Would You think the Mallory 150's be better than OD715's for the Express ? I might try Mallorys in there - I have them easily available..

mat · Post by **mat** » Tue Oct 31, 2006 3:24 pm

Fitting the blank wood panel..

[img

1200]http://www.pichotel.com/pic/16028B31e/84278.jpg[/img]

keithrick · Post by **keithrick** » Tue Oct 31, 2006 6:37 pm

Mat,

Great build. I will try to check voltages tomorrow, Got to take the kids trick or treating tonight!

I personally like the Mallory's better in the Express Build. I used a combination of Mallory's and OD PS series in my Rocket.

How does it sound? Better then your Dumble build? Just curious.

Keith

Elcabong · Post by **Elcabong** » Wed Nov 01, 2006 1:37 am

Nice work Mat!

I think your V2 voltages are fine. The Kelly90 schematic shows 261V and 2.9V

keithrick · Post by **keithrick** » Wed Nov 01, 2006 2:16 am

Thanks Elcabong,

I should have thought of that! Saves me from ripping my amp apart to check voltages!

Mat- How does it sound?

mat · Post by **mat** » Wed Nov 01, 2006 6:18 am

keithrick wrote:Mat,

Great build. I will try to check voltages tomorrow, Got to take the kids trick or treating tonight!

I personally like the Mallory's better in the Express Build. I used a combination of Mallory's and OD PS series in my Rocket.

How does it sound? Better then your Dumble build? Just curious.

Keith

Ok, Thanks Keith, I will try the Mallorys after playing with it for a while.

I cannot say much of the overdrive sound (haven't had chance to crank it properly), but the cleans are amazingly responsive and chimy

It is very nice to play chords with bare fingers. Really dynamic!

The Express is whole different deal than my nonHRM D-clone. Much more 'in your face' if that makes any sense. Although both are very dynamic amps.

With my tele it is almost too much. I have on/off/on on the bright switch and the off position with little additional treble pot seems to work fine with the tele. But with my humbucker guitar it is just right.

I was wondering how this beast communicates with P90's ?

Thanks Elcabong for the V2 voltage confirmation. I wonder if the other voltages are right too ? I did not find the plate voltages when searching the forum, have to dig deeper.

Really I have to figure a way to get the overdrive sounds more reasonable levels. As I said I tried the simple MV but was not happy with that (hope I got it right). Also I was thinking to build some kind of simple attenuator. Anyone got a favourite ? schem ?

Thanks,

Elcabong · Post by **Elcabong** » Wed Nov 01, 2006 5:51 pm

mat wrote:Really I have to figure a way to get the overdrive sounds more reasonable levels. As I said I tried the simple MV but was not happy with that (hope I got it right). Also I was thinking to build some kind of simple attenuator. Anyone got a favourite ? schem ?

Thanks,

I use a MiniMass with my Express clone. It does alter the sound, removing higher frequencies, but it is not a bad thing with such a bright amp. When I want a cleaner sound, I bypass the attenuator and lower the gain using a split load on the second stage and a 100k pot with a 56k before the 3rd stage. I have also lowered the PI gain replacing the 470, 10K tail resistors with 1.2k, 47K values.

mat · Post by **mat** » Wed Nov 01, 2006 7:12 pm

Elcabong wrote:
mat wrote:Really I have to figure a way to get the overdrive sounds more reasonable levels. As I said I tried the simple MV but was not happy with that (hope I got it right). Also I was thinking to build some kind of simple attenuator. Anyone got a favourite ? schem ?

Thanks,
I use a MiniMass with my Express clone. It does alter the sound, removing higher frequencies, but it is not a bad thing with such a bright amp. When I want a cleaner sound, I bypass the attenuator and lower the gain using a split load on the second stage and a 100k pot with a 56k before the 3rd stage. I have also lowered the PI gain replacing the 470, 10K tail resistors with 1.2k, 47K values.

Thanks Elcabong for the tips

,

mss1 · Post by **mss1** » Wed Nov 01, 2006 10:23 pm

mat wrote:
Elcabong wrote:
mat wrote:Really I have to figure a way to get the overdrive sounds more reasonable levels. As I said I tried the simple MV but was not happy with that (hope I got it right). Also I was thinking to build some kind of simple attenuator. Anyone got a favourite ? schem ?

Thanks,
I use a MiniMass with my Express clone. It does alter the sound, removing higher frequencies, but it is not a bad thing with such a bright amp. When I want a cleaner sound, I bypass the attenuator and lower the gain using a split load on the second stage and a 100k pot with a 56k before the 3rd stage. I have also lowered the PI gain replacing the 470, 10K tail resistors with 1.2k, 47K values.
Thanks Elcabong for the tips ,

Check out the previous thread talking about an article by Gerald Weber (in the latest Vintage Guitar magazine) on building a simple and cheap attenuator...

As I remember;

On an 8ohm 50w amp he proposes adding an 8ohm 50w resistor in parallel with the output (splitting the power between the resistor and the speaker) which brings the impedance down to 4 ohms, so it takes an additional 4ohm 50w resistor in series to bring it back up to 8 ohms again. This gives about 6db cut.

Just add another similar stage again for 12 db. He says that adding any more stages would affect the tone...

This is all built into a small metal, heat-sinking box with jacks and a switch for each stage, to make it easy to use and portable.

Of course, louder amps take higher wattage resistors. It will drive the amp a lot harder at lower perceived volumes so it may bring out other issues.... (Hopefully just great tone...)

I have not seen any comments on how it sounds, but I have my Vishay metal resistors on their way and I can't wait to try it out.

Please do not rely on my memory, make sure to get the article for the details.

Anyone else try this or a similar approach yet?

MSS1

mat · Post by **mat** » Mon Nov 06, 2006 1:33 am

Thanks MSS1,

I ordered parts for a attenuator - have to wait 2-3 weeks

I would like to know how my voltages seems to You guys ? I'm noob so couple of noob questions:

Would the 410V cause the amp to have more headroom than 400V ?

Should I adjust the dropping resistors to match the voltages of the Kelly Revised Schem ? My B+'s are like 7-19V higher than in the schem. Should I get feedback earlier then ? A less agressive amp ?

My voltages:

B+1 = 410V
B+2 = 399V (1k 25w)
B+3 = 313V (18k 3w)
B+4 = 292V (10k 3w)
B+5 = 274V (10k 3w)

voltages on the schem:

B+1 = 395V
B+2 = 380V
B+3 = 298V
B+3 = 282V
B+4 = 267V

Thanks,

Humbucker · Post by **Humbucker** » Mon Nov 06, 2006 8:44 am

Fired my version of Express Kelly up this weekend with Hot Mama attenuator and 2x12 pine cabinet with Legend V12A:s.
The guys I jammed with were all smiles and I myself was almost drooling: touch, tone and growl with a giant punch in a flaming velvet boxing glove. The cabinet did it. I'm still shivering.

We don't need no stinking effects. Ever.

mat · Post by **mat** » Mon Nov 06, 2006 3:48 pm

Humbucker wrote:Fired my version of Express Kelly up this weekend with Hot Mama attenuator and 2x12 pine cabinet with Legend V12A:s.
The guys I jammed with were all smiles and I myself was almost drooling: touch, tone and growl with a giant punch in a flaming velvet boxing glove. The cabinet did it. I'm still shivering.

We don't need no stinking effects. Ever.

Good to know, thanks

Humbucker · Post by **Humbucker** » Tue Nov 07, 2006 8:53 am

Oh...listen to your amp first, don't get caught on voltages and values. The cabinet and speakers affect the TW sound more than I could dream of after 30 years of Marshalls, Fenders, stacks, combos, rack-mounts and even modeling amps. Tried four different speakers and got four very different sounds. With ubiquitous Celestion T75 the amp sounded harsh and shrill, no "give" anywhere.

But if you are anxious to know...You have your V's checked, and I could do the same in a few days and report if that is any use to you?
If I remember correctly the voltages were quite on the nose with the schematic but I'll check this.

mat · Post by **mat** » Tue Nov 07, 2006 6:44 pm

Humbucker wrote:Oh...listen to your amp first, don't get caught on voltages and values. The cabinet and speakers affect the TW sound more than I could dream of after 30 years of Marshalls, Fenders, stacks, combos, rack-mounts and even modeling amps. Tried four different speakers and got four very different sounds. With ubiquitous Celestion T75 the amp sounded harsh and shrill, no "give" anywhere.

But if you are anxious to know...You have your V's checked, and I could do the same in a few days and report if that is any use to you?
If I remember correctly the voltages were quite on the nose with the schematic but I'll check this.

Hi Humbucker,

Yes I would very much like to know the voltages of Your amp if that is not too much trouble for You.

Do You have any sounclips available ? Would be cool to check them

Where are You located in Finland. I live in Helsinki.

cheers,

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