JLM 60Watt Power AMP Kit

Support for JLM Audio Kits

Moderator: Joe Malone

User avatar
Joe Malone
Site Admin
Posts: 1572
Joined: Wed Jan 24, 2007 11:35 pm
Location: Brisbane, Australia
Contact:

Re: JLM 60Watt Power AMP Kit

Postby Joe Malone » Wed Apr 19, 2017 10:29 am

rtchau wrote:
Joe Malone wrote:
HI Richard
If the volume pot is turned fully down does the amp motorboat?


Hi Joe,

No - it only seems to go bananas after the volume pot is turned up past 50%, prior to that it starts to hum after 10-20%, and nothing at 0%.


OK what value is the volume pot? If 10k log connect a 4.7k resistor between the center wiper and 0v and retest to see if pot can get to 100% with only hum.
Joe :-)
JLM Audio
Capturing Audio without Injury

FaceOfShmuck
Posts: 3
Joined: Mon Jul 03, 2017 8:55 am

Re: JLM 60Watt Power AMP Kit

Postby FaceOfShmuck » Tue Jul 25, 2017 10:59 am

Hi guys!

I'm building a pair of 2-way powered monitors using these amps. I'm wondering if there is a way to run 2 amp kits off 1 power supply (160VA trans) and drop the wattage on the just the tweeter side amp? Not sure if this is doable, really appreciate any help!

User avatar
Joe Malone
Site Admin
Posts: 1572
Joined: Wed Jan 24, 2007 11:35 pm
Location: Brisbane, Australia
Contact:

Re: JLM 60Watt Power AMP Kit

Postby Joe Malone » Tue Jul 25, 2017 11:19 am

FaceOfShmuck wrote:Hi guys!

I'm building a pair of 2-way powered monitors using these amps. I'm wondering if there is a way to run 2 amp kits off 1 power supply (160VA trans) and drop the wattage on the just the tweeter side amp? Not sure if this is doable, really appreciate any help!


If you were bridging just two amps the highest power rails allowed are +/-25vdc so use a 2 x 18vac transformer. This also lowers the wattage on the single amps as they are not running on the full +/-35v. So all works out perfectly.

But if you are using a single amp for woofer and tweeter on +/-35vdc then the only way is to add a resistor in series with the tweeter. So if tweeter is 8 ohms then adding a 8ohm resistor would half the wattage to the tweeter and drop it level 6dB.

But lowering the power of the amp to the tweeter does nothing to help it survive overload as clipping damages the tweeter more than extra clean power.

So best is to just give the tweeter the same power but add a small fuse inline to the tweeter for safety.
Joe :-)

JLM Audio

Capturing Audio without Injury

FaceOfShmuck
Posts: 3
Joined: Mon Jul 03, 2017 8:55 am

Re: JLM 60Watt Power AMP Kit

Postby FaceOfShmuck » Tue Jul 25, 2017 12:59 pm

Thanks for the response Joe!

Not bridging, bi-amping. So is it still ok to run 2 amps off 1 power supply if they are not bridged?

I have some 160VA, 30V/30V transformers. Are these suitable for running 2 amps in this application?

And not so much worried about the clipping aspect as the usual 1/2 power to tweeter rule.
So are you saying having the same power for woofer and tweeter is fine? I can fuse all over the place if needed.

User avatar
Joe Malone
Site Admin
Posts: 1572
Joined: Wed Jan 24, 2007 11:35 pm
Location: Brisbane, Australia
Contact:

Re: JLM 60Watt Power AMP Kit

Postby Joe Malone » Tue Jul 25, 2017 1:05 pm

FaceOfShmuck wrote:Thanks for the response Joe!

Not bridging, bi-amping. So is it still ok to run 2 amps off 1 power supply if they are not bridged?

Yes fine to run as many amps as the transformer can handle VA Wattage wise

I have some 160VA, 30V/30V transformers. Are these suitable for running 2 amps in this application?

No highest AC volts is 2 x 25vac to make +/-35v to 37.5vdc. The 2 x 30V will make around +/-42v to 45v which is to high.

And not so much worried about the clipping aspect as the usual 1/2 power to tweeter rule.
So are you saying having the same power for woofer and tweeter is fine? I can fuse all over the place if needed.

Yes and fuse the tweeter is good idea.
Joe :-)

JLM Audio

Capturing Audio without Injury

FaceOfShmuck
Posts: 3
Joined: Mon Jul 03, 2017 8:55 am

Re: JLM 60Watt Power AMP Kit

Postby FaceOfShmuck » Tue Jul 25, 2017 1:35 pm

Excellent thanks Joe!! Much appreciated.

I'll get my hands on some new transformers and go ahead with my build. I'll post on here again when it starts coming together.

nickfranklin
Posts: 2
Joined: Wed May 17, 2017 6:24 pm

Re: JLM 60Watt Power AMP Kit

Postby nickfranklin » Wed Jul 26, 2017 11:54 am

Just wanted to say, these amps are red hot. I built a pair for my good friend and excellent mix engineer Tom Garnett to run a small pair of hifi speakers for referencing and they sound great. I tested the amps on my PMC's and they sounded every bit as good as my far more expensive Haffler.

User avatar
Joe Malone
Site Admin
Posts: 1572
Joined: Wed Jan 24, 2007 11:35 pm
Location: Brisbane, Australia
Contact:

Re: JLM 60Watt Power AMP Kit

Postby Joe Malone » Wed Jul 26, 2017 1:08 pm

nickfranklin wrote:Just wanted to say, these amps are red hot. I built a pair for my good friend and excellent mix engineer Tom Garnett to run a small pair of hifi speakers for referencing and they sound great. I tested the amps on my PMC's and they sounded every bit as good as my far more expensive Haffler.


Thanks for the great comment Nick. :-)

Can I or you add this to the AMP kit review comments on the bottom of the amp kit webshop page?

As I am trying to get all reviews and comments for all kits on the webshop for buyers to see easily :-)

https://www.jlmaudio.com/shop/amp-kit.html

Thanks Again
Joe :-)

JLM Audio

Capturing Audio without Injury

nickfranklin
Posts: 2
Joined: Wed May 17, 2017 6:24 pm

Re: JLM 60Watt Power AMP Kit

Postby nickfranklin » Wed Jul 26, 2017 4:29 pm

Done... not sure if it worked though, I can't see it yet?


Joe Malone wrote:
nickfranklin wrote:Just wanted to say, these amps are red hot. I built a pair for my good friend and excellent mix engineer Tom Garnett to run a small pair of hifi speakers for referencing and they sound great. I tested the amps on my PMC's and they sounded every bit as good as my far more expensive Haffler.


Thanks for the great comment Nick. :-)

Can I or you add this to the AMP kit review comments on the bottom of the amp kit webshop page?

As I am trying to get all reviews and comments for all kits on the webshop for buyers to see easily :-)

https://www.jlmaudio.com/shop/amp-kit.html

Thanks Again

User avatar
Joe Malone
Site Admin
Posts: 1572
Joined: Wed Jan 24, 2007 11:35 pm
Location: Brisbane, Australia
Contact:

Re: JLM 60Watt Power AMP Kit

Postby Joe Malone » Wed Jul 26, 2017 5:12 pm

nickfranklin wrote:Done... not sure if it worked though, I can't see it yet?


Joe Malone wrote:
nickfranklin wrote:Just wanted to say, these amps are red hot. I built a pair for my good friend and excellent mix engineer Tom Garnett to run a small pair of hifi speakers for referencing and they sound great. I tested the amps on my PMC's and they sounded every bit as good as my far more expensive Haffler.


Thanks for the great comment Nick. :-)

Can I or you add this to the AMP kit review comments on the bottom of the amp kit webshop page?

As I am trying to get all reviews and comments for all kits on the webshop for buyers to see easily :-)

https://www.jlmaudio.com/shop/amp-kit.html

Thanks Again


HI Nick Yes it is up on the website now Thanks :-)
Joe :-)

JLM Audio

Capturing Audio without Injury

kevanatkins
Posts: 4
Joined: Fri Aug 25, 2017 6:14 pm

Re: JLM 60Watt Power AMP Kit

Postby kevanatkins » Fri Aug 25, 2017 9:27 pm

I’m having trouble getting this to work. The amp does not pass any signal at all. Power supply-wise I’m running off 2x Mean Well LRS-150-24 supplies to create my +/- rails. I’m taking a balanced signal from my RME Fireface 400. I know there’s a signal present at the input (a test tone), which is measuring at 300mV on my meter and my power rails are measuring +25V/0V/-25V. Heatsink-wise, it's attached to a die-cast aluminium case and it's not even getting warm, so I don't think there are any internal shorts. What are some good tests I can do to diagnose the problem?

User avatar
Joe Malone
Site Admin
Posts: 1572
Joined: Wed Jan 24, 2007 11:35 pm
Location: Brisbane, Australia
Contact:

Re: JLM 60Watt Power AMP Kit

Postby Joe Malone » Fri Aug 25, 2017 10:16 pm

kevanatkins wrote:I’m having trouble getting this to work. The amp does not pass any signal at all. Power supply-wise I’m running off 2x Mean Well LRS-150-24 supplies to create my +/- rails. I’m taking a balanced signal from my RME Fireface 400. I know there’s a signal present at the input (a test tone), which is measuring at 300mV on my meter and my power rails are measuring +25V/0V/-25V. Heatsink-wise, it's attached to a die-cast aluminium case and it's not even getting warm, so I don't think there are any internal shorts. What are some good tests I can do to diagnose the problem?


Do you have a wire link between mute and -V terminal so the amp is not in mute?

Otherwise best to put up a couple of photos so I can check your wiring.
Joe :-)

JLM Audio

Capturing Audio without Injury

kevanatkins
Posts: 4
Joined: Fri Aug 25, 2017 6:14 pm

Re: JLM 60Watt Power AMP Kit

Postby kevanatkins » Mon Aug 28, 2017 10:40 pm

Yikes. I didn't get a notification about your reply. Anyway...

I haven't made much headway since. There's no link on the mute terminal. I've attached some photos.
You do not have the required permissions to view the files attached to this post.

User avatar
Joe Malone
Site Admin
Posts: 1572
Joined: Wed Jan 24, 2007 11:35 pm
Location: Brisbane, Australia
Contact:

Re: JLM 60Watt Power AMP Kit

Postby Joe Malone » Tue Aug 29, 2017 8:07 am

kevanatkins wrote:Yikes. I didn't get a notification about your reply. Anyway...

I haven't made much headway since. There's no link on the mute terminal. I've attached some photos.


You must fit the link between mute and -V to turn the amp ON. Without the link you will be in mute so will never get anything out of the amp.

Also for full gain NO resistor should be fitted to the volume terminals. Shorting the vol +/- turns the volume right down.
Joe :-)

JLM Audio

Capturing Audio without Injury

kevanatkins
Posts: 4
Joined: Fri Aug 25, 2017 6:14 pm

Re: JLM 60Watt Power AMP Kit

Postby kevanatkins » Tue Aug 29, 2017 7:51 pm

Joe Malone wrote:
kevanatkins wrote:Yikes. I didn't get a notification about your reply. Anyway...

I haven't made much headway since. There's no link on the mute terminal. I've attached some photos.


You must fit the link between mute and -V to turn the amp ON. Without the link you will be in mute so will never get anything out of the amp.

Also for full gain NO resistor should be fitted to the volume terminals. Shorting the vol +/- turns the volume right down.


Fitted the link and removed the resistor. Still nothing.

Return to “JLM Audio Kits”

Who is online

Users browsing this forum: No registered users and 8 guests