MusicRadar

longi · 03-22-2009, 11:33 AM

Anybody know of anyone in the Thames Valley/Hampshire/West Sussex area that could modifies amps? I have a Laney LC50 mk2 and i'd like to squeeze just a little more gain from it.
Cheers,
Paul.

tiptonamps · 03-22-2009, 06:01 PM

Quote:

Originally Posted by longi

Anybody know of anyone in the Thames Valley/Hampshire/West Sussex area that could modifies amps? I have a Laney LC50 mk2 and i'd like to squeeze just a little more gain from it.
Cheers,
Paul.

Hi,

If you are OK with a soldering iron and a schematic, try this:

Change the 2K7 Ohm cathode resistor labelled R11 on the schematic to 1K5 Ohms. This will give you a modest hike in gain.

a 1/2W resistor will be fine.

Cost? Around 13p if you DIY

HTH,

Trev

www.tipton-amps.co.uk

longi · 03-22-2009, 06:55 PM

Thanks for coming back to me.
I'm not too shabby with a soldering iron, I have an electrical background so it shouldn't be a problem. I guess I would be using a 240V rated resistor then? I'm looking to get a "Classic Metal" sound, ie, Randy Rhoads, Queensryche, George Lynch amounts, not Uber Metal. Would a 1k5 give me that much? I haven't used the amp in about 6-8 weeks, I'm a bit worried i'm going to get a whack from the amp if i'm not carefull. What the best way to discharge the residual voltages from the amp other than shorting out the caps?

manicguitarist2 · 03-22-2009, 07:08 PM

Quote:

Originally Posted by longi

Thanks for coming back to me.
I'm not too shabby with a soldering iron, I have an electrical background so it shouldn't be a problem. I guess I would be using a 240V rated resistor then? I'm looking to get a "Classic Metal" sound, ie, Randy Rhoads, Queensryche, George Lynch amounts, not Uber Metal. Would a 1k5 give me that much? I haven't used the amp in about 6-8 weeks, I'm a bit worried i'm going to get a whack from the amp if i'm not carefull. What the best way to discharge the residual voltages from the amp other than shorting out the caps?

Discharge the caps by powering it up, playing through it, and then whilst it is switched on, pull out the mains cable. The caps will mostly discharge through the speaker (before the valves become infinite resistance). Still be careful though. If you are careful, you are fine.

tiptonamps · 03-22-2009, 07:13 PM

Quote:

Originally Posted by longi

Thanks for coming back to me.
I'm not too shabby with a soldering iron, I have an electrical background so it shouldn't be a problem. I guess I would be using a 240V rated resistor then? I'm looking to get a "Classic Metal" sound, ie, Randy Rhoads, Queensryche, George Lynch amounts, not Uber Metal. Would a 1k5 give me that much? I haven't used the amp in about 6-8 weeks, I'm a bit worried i'm going to get a whack from the amp if i'm not carefull. What the best way to discharge the residual voltages from the amp other than shorting out the caps?

OK,

Maplins do metal film resistors that can handle 0.6W and 500V, no problem.

If you lower the value of the cathode resistor, this increases the gain, within limits. Too low a value will stop the valve working properly. Plus the amp will become unstable and it'll start to squeal and/or 'motorboat'

1K5 is a value that will keep the valve happy, whilst stepping up the grunt. You should be able to get a fairly distorted tone as a result.

To safely discharge the smoothing capacitors in the power supply, connect a length of wire terminated with a pair of mini 'croc' clips between pin 1 or 6 of a preamp valve socket and the chassis. The anode resistor will allow the stored charge to gently leak to earth.

Remember to remove the lead *before* you power up.

regards,

Trev

www.tipton-amps.co.uk

longi · 03-22-2009, 08:46 PM

Cool thanks. How long roughly does it take to discharge?

tiptonamps · 03-22-2009, 09:27 PM

Quote:

Originally Posted by longi

Cool thanks. How long roughly does it take to discharge?

Hi,

Thirty seconds will see the caps discharged. Leave the lead in place whilst you work. That way you're safe

regards

Trev

www.tipton-amps.co.uk

longi · 03-23-2009, 06:55 AM

Excellent! Thanks very much for the advice.

ecc83 · 03-23-2009, 07:43 AM

Hmmm?

Pardon an Old F's intrusion but the Laney circuit before me does not tally with the former information.

The first two triode stages already have 1.5k cathode R's and they are bypassed by 25mfd's so the gain is as high as you are going to get it there I feel.

You should be able to screw a few more dB's out if you increased the anode load R of the third satge to say 220-270K and bypassed the 820Ohm cathode resistor, you could experiment with values of 0.1, 1mfd. and upward. the lower values giving a bit of treble boost. Gain will be at the expense of preamp headroom to some extent but YCHE!

And. Ooer! If I had one I think I would mod the bias circuitry so that I could setup Ia. Mind, this is the LC50 combo map that I found, don't know if the mkll is better in this respect?

Dave.

MattANJH · 03-23-2009, 01:35 PM

OD pedal to save modding?

03-22-2009, 11:33 AM	#1
longi Senior Member Join Date: Aug 2008 Posts: 154	Modding my Laney for more gain. Anybody know of anyone in the Thames Valley/Hampshire/West Sussex area that could modifies amps? I have a Laney LC50 mk2 and i'd like to squeeze just a little more gain from it. Cheers, Paul.

03-23-2009, 01:35 PM	#10
MattANJH Senior Member Join Date: Feb 2008 Location: Wigan Posts: 3,391	OD pedal to save modding? __________________ Ye Olde Original MATHSBOY!! Previously: A Near Jaded Heart Post Count: 3,121

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

MusicRadar

Buy here

From the makers of

03-22-2009, 06:55 PM	#3
longi Senior Member Join Date: Aug 2008 Posts: 154	Thanks for coming back to me. I'm not too shabby with a soldering iron, I have an electrical background so it shouldn't be a problem. I guess I would be using a 240V rated resistor then? I'm looking to get a "Classic Metal" sound, ie, Randy Rhoads, Queensryche, George Lynch amounts, not Uber Metal. Would a 1k5 give me that much? I haven't used the amp in about 6-8 weeks, I'm a bit worried i'm going to get a whack from the amp if i'm not carefull. What the best way to discharge the residual voltages from the amp other than shorting out the caps?

03-22-2009, 08:46 PM	#6
longi Senior Member Join Date: Aug 2008 Posts: 154	Cool thanks. How long roughly does it take to discharge?

03-23-2009, 06:55 AM	#8
longi Senior Member Join Date: Aug 2008 Posts: 154	Excellent! Thanks very much for the advice.

03-23-2009, 07:43 AM	#9
ecc83 Senior Member Join Date: Sep 2006 Location: northampton uk Posts: 2,612	Hmmm? Pardon an Old F's intrusion but the Laney circuit before me does not tally with the former information. The first two triode stages already have 1.5k cathode R's and they are bypassed by 25mfd's so the gain is as high as you are going to get it there I feel. You should be able to screw a few more dB's out if you increased the anode load R of the third satge to say 220-270K and bypassed the 820Ohm cathode resistor, you could experiment with values of 0.1, 1mfd. and upward. the lower values giving a bit of treble boost. Gain will be at the expense of preamp headroom to some extent but YCHE! And. Ooer! If I had one I think I would mod the bias circuitry so that I could setup Ia. Mind, this is the LC50 combo map that I found, don't know if the mkll is better in this respect? Dave.