I turned my two stereo amps into mono-blocks for 10 dollars

I had posed a question in the Aleph J thread a number of months ago to see if there was any reason I shouldn't try the following, and not receiving any negative feedback, I went ahead and made the changes this past week.

I had built an M2 and an Aleph J a while back. I've always loved the stereo imaging and sound-stage depth I get from mono-blocks, so I wanted to convert my amps to mono-blocks - but the expense for the extra chassis and power supplies kept me from doing so.

Since the Aleph J and the M2 use the same power supply, I decided to swap an Aleph J channel for an M2 channel between amps, so each amp has one Aleph J and one M2 board. I installed a heavy duty DPDT switch on the back of each amp, unhooked the V+ and V- from the power supply to the boards, and instead ran the V+ and V- to the center pole of the switch, and then ran lines from the switch to the V+ and V- of the audio boards. I didn't do anything with the ground lines.

The power supply in each amp now only powers one board depending on the position of the switch, and I change the RCA input, speaker outputs and switch position depending on whether I want to hear M2 mono-blocks or Aleph J mono-blocks.

How did it turn out? Really well. I always had a bit of a ground loop that I could hear in my Aleph J if my ears were close to the speakers. Beyond the increase in separation that mono-blocks bring, now both the M2 and the Aleph J are totally silent with my ears right next to the drivers.

Both amps were built with Antek 18V 300 VAC transformers. As a stereo amp with this transformer, the M2 sounded very pretty for jazz, and folk type music, but wouldn't really rock to satisfaction. Dedicating the power supply to a single audio board has given the M2 much more bass drive and punch. I was actually shocked at the difference, as I wasn't expecting it. Now the amp can rock as well.

Hear are a few not-so-great pictures that demonstrate the change.

P.S. Not that there would be any reason to, but as 6L6 pointed out when I asked about the idea earlier, you would never want to flip the switch while the amp is running.
 

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Russellc

Member
Paid Member
2003-03-06 12:59 am
midwest
Great Idea! If I didn't use my M2 and AlephJ in different systems, I would be right on this. Maybe after the boat load of half finished Amps are done....Have thought for some time to cannabalize two of my amps powers supplies, and make a movable one. Your idea would negate moving that power supply around all the time.

For someone with a single system, your idea is perfect, plus, true mono blocks.

Russellc
 
@aljordan

even better, build separate psu box with CLC and use neutrik Powercon and you'll have unlimited combinations of amplifier with 25V supply.

even crazier, put separate box for toroid and cap bank with neutrik connector. with 50V capacitor then you can swap different toroid started from 18Vdc for AlephJ up to the level on Aleph 2 :)

instead of monoblock, i prefer separate psu, no interference from toroid/inductor, easy plug and play just like PassLab XS series

https://www.passlabs.com/amplifier/xs-300
 
@aljordan

even better, build separate psu box with CLC and use neutrik Powercon and you'll have unlimited combinations of amplifier with 25V supply.

even crazier, put separate box for toroid and cap bank with neutrik connector. with 50V capacitor then you can swap different toroid started from 18Vdc for AlephJ up to the level on Aleph 2 :)

instead of monoblock, i prefer separate psu, no interference from toroid/inductor, easy plug and play just like PassLab XS series

https://www.passlabs.com/amplifier/xs-300

I have seen threads of other people doing this (or planning to do it), so thought I'd do the same. However, I was unclear about some things, such as:

- Running audio board grounds back to the separate power supply and if it would indeed help with ground loops since they would still be grounding to a common point (not true mono-blocks).
- Would I still need capacitance at the chassis with the audio boards.
- In general, much more chance for me to do something stupid because I really don't know electronics very well.

It is still something I would like to try if there are advantages over what I've done.
 
Great idea. Audio chimerism at its best!

Take it one step further. Most of your 25w (+/-24V) amps use an N-ch and P-ch MOSFET pair. Mount the MOSFETs on flying leads with snubber local snubber boards that contain the gate stopper, the protection zerner, and an optional series RC snubber from drain to gate. The flying leads go to Molex quick release connectors on the main amp board. The PSU goes to Molex quick release on the main amp board (or Faston spades if you prefer). The speakers go to Molex quick release on the main amp board (or Faston spades if you prefer). The audio input goes to Molex KK (2 or 3 pin dep on SE or Bal) on the main board (3-pin would be universal).

All main amp boards have the same standoff bolt holes (UMS compat if you like).

Now swapping out amp modules (be they F5, F6, M2, M2X, etc...) takes 2 minutes and you can be sure the connections are all good. The amps of course, need to be designed with the connectors in mind.

I have done this on one amp so far, and intend to build future amps following the same format.

797481d1574673293-alpha-nirvana-39w-8ohm-class-amp-sound-00-jpg


799772d1575528651-alpha-nirvana-39w-8ohm-class-amp-slb-v2-02-jpg


You get the idea...

When it comes time to test out a new amp, the infrastructure of a chassis, PSU, output MOSFETs, audio inputs, speaker protection SSR's, soft start, IEC, mains switch and fuse, adio input jacks, speaker output terminals, grounding, etc.. are all in place. You can literally hok up up a brand-new-never-made-sound-before amp to a working and fully built chassis in 2 minutes. Listen to it for months or years, and when you get the urge to try a new amp (and don't tell me you don't get these urges), you can make the new amp and skip the teeth-pulling experience of making and fitting a new chassis to the new amp. Unless you like doing that sort of thing - then you don't need this.

Combine this with your chemeric monblock chassis, the world is your oyster.
 
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Russellc

Member
Paid Member
2003-03-06 12:59 am
midwest
I had posed a question in the Aleph J thread a number of months ago to see if there was any reason I shouldn't try the following, and not receiving any negative feedback, I went ahead and made the changes this past week.

I had built an M2 and an Aleph J a while back. I've always loved the stereo imaging and sound-stage depth I get from mono-blocks, so I wanted to convert my amps to mono-blocks - but the expense for the extra chassis and power supplies kept me from doing so.

Since the Aleph J and the M2 use the same power supply, I decided to swap an Aleph J channel for an M2 channel between amps, so each amp has one Aleph J and one M2 board. I installed a heavy duty DPDT switch on the back of each amp, unhooked the V+ and V- from the power supply to the boards, and instead ran the V+ and V- to the center pole of the switch, and then ran lines from the switch to the V+ and V- of the audio boards. I didn't do anything with the ground lines.

The power supply in each amp now only powers one board depending on the position of the switch, and I change the RCA input, speaker outputs and switch position depending on whether I want to hear M2 mono-blocks or Aleph J mono-blocks.

How did it turn out? Really well. I always had a bit of a ground loop that I could hear in my Aleph J if my ears were close to the speakers. Beyond the increase in separation that mono-blocks bring, now both the M2 and the Aleph J are totally silent with my ears right next to the drivers.

Both amps were built with Antek 18V 300 VAC transformers. As a stereo amp with this transformer, the M2 sounded very pretty for jazz, and folk type music, but wouldn't really rock to satisfaction. Dedicating the power supply to a single audio board has given the M2 much more bass drive and punch. I was actually shocked at the difference, as I wasn't expecting it. Now the amp can rock as well.

Hear are a few not-so-great pictures that demonstrate the change.

P.S. Not that there would be any reason to, but as 6L6 pointed out when I asked about the idea earlier, you would never want to flip the switch while the amp is running.

What should the DPDT switch be rated? 10 amp sufficient? Suggested switch? Always fearing my clever Puddy Cat will walk behind switch switch in mid Jam.....
Couldn't quite make out numbers on switch blowing up your supplied pic.

Would like if possible a semi protected switch to prevent Cat's shinanigans, as well as prevent owner/operator mishap as well!

Guess I could locate switch inside chassis.
Russellc
 
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Hopefully the picture will help. I don't have the packaging material so I don't know the exact model number. I just went to the local electronics distributor and found a reasonably heavy duty switch. The switch takes quite a bit of force to flip, so I don't think your cat could flip it, unless she is a mountain lion.

Alan
 

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Russellc

Member
Paid Member
2003-03-06 12:59 am
midwest
Hopefully the picture will help. I don't have the packaging material so I don't know the exact model number. I just went to the local electronics distributor and found a reasonably heavy duty switch. The switch takes quite a bit of force to flip, so I don't think your cat could flip it, unless she is a mountain lion.

Alan

Thanks! Can't wait to duplicate your efforts with my M2 and Aleph J.

Russellc