I found this video helpful:
https://www.youtube.com/watch?v=b9FC9fAlfQE
With a half decent iron and small tip, e.g. Hakko FX-888D and 1.6mm chisel tip, a flux pen, desoldering braid, 0.4mm solder and tweezers I've had no problem.
I practised with one of these:
SMT SMD Component Welding Practice Blue PCB Board Soldering Solder DIY Suite Kit
Colin
Awesome. Thanks for your help Anand. I really appreciate it.
The SMPS300RE might be a tad underpowered for a dual mono build. I'd consider the SMPS500R. Get the ±36 V version if you're going with mono MOD286es. Keep in mind that the "300 W" specified for the 300RE is "music power" and assumes a 2.5x crest factor. In reality it's a 120 W supply. If you draw more than that continuously, you'll blow one of the dual diodes on the secondary and the supply will die. Ask me how I found this out...
At least it dies gracefully. Similarly, I'd expect the 500R to be good for 500/2.5 = 200 W continuously. Unfortunately this is how audio SMPSes are specified and it is not unique to Connex. Morale: You gotta read the spec sheet in its entirety.A Power-86 with a 400 VA transformer would be a good fit, however, nothing says you can't get started with the 160 VA available. I'd just leave enough room in the chassis for the 400 VA to be installed at a later date. An Antek AS-4224 will set you back about $50 so - at least for those in the US - upgrading the transformer need not break the bank.
The ModuShop/DIY Audio Store Dissipante 2U is great for a dual mono MOD286 build. Larger doesn't hurt (except the wallet) but isn't needed.
Note that ModuShop offers to cut holes in the panes for a very reasonable fee ($35 I think). As the rear panel is steel, it is totally worth the money to have ModuShop poke the holes for you. The front panel is aluminum. If you have a drill press or a drill stand, that's machinable by most people. If you're looking to cut holes in it by hand, I'd throw money at ModuShop to have them do the work. Yes, it's more money, but you look at the front panel of your amp a lot... Just saying.
Another option is the BZ4309 chassis from eBay. It's available from many vendors. I got mine from "along1986090". It's slightly lower quality and slightly higher cost than the ModuShop enclosure, but it is all aluminum so a bit easier to work with.
I just did the math for someone else (in email): The total build cost of a dual mono MOD286 amp is around $780 including chassis, connectors, power supply, everything. If you already have the power supply components available, you'll shave $120ish off that number. The numbers assume that you don't go totally overboard with bling components carved from solid blocks of Unobtanium by Ipswich virgins.
Tom
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@Tom. Expect my order in the next few days.
I'm looking forward to it. Thanks. Have a safe trip.
Tom
Awesome. Thanks for your help Anand. I really appreciate it.
The SMPS300RE might be a tad underpowered for a dual mono build. I'd consider the SMPS500R. Get the ±36 V version if you're going with mono MOD286es. Keep in mind that the "300 W" specified for the 300RE is "music power" and assumes a 2.5x crest factor. In reality it's a 120 W supply. If you draw more than that continuously, you'll blow one of the dual diodes on the secondary and the supply will die. Ask me how I found this out...
A Power-86 with a 400 VA transformer would be a good fit, however, nothing says you can't get started with the 160 VA available. I'd just leave enough room in the chassis for the 400 VA to be installed at a later date. An Antek AS-4224 will set you back about $50 so - at least for those in the US - upgrading the transformer need not break the bank.
The ModuShop/DIY Audio Store Dissipante 2U is great for a dual mono MOD286 build. Larger doesn't hurt (except the wallet) but isn't needed.
Note that ModuShop offers to cut holes in the panes for a very reasonable fee ($35 I think). As the rear panel is steel, it is totally worth the money to have ModuShop poke the holes for you. The front panel is aluminum. If you have a drill press or a drill stand, that's machinable by most people. If you're looking to cut holes in it by hand, I'd throw money at ModuShop to have them do the work. Yes, it's more money, but you look at the front panel of your amp a lot... Just saying.
Another option is the BZ4309 chassis from eBay. It's available from many vendors. I got mine from "along1986090". It's slightly lower quality and slightly higher cost than the ModuShop enclosure, but it is all aluminum so a bit easier to work with.
I just did the math for someone else (in email): The total build cost of a dual mono MOD286 amp is around $780 including chassis, connectors, power supply, everything. If you already have the power supply components available, you'll shave $120ish off that number. The numbers assume that you don't go totally overboard with bling components carved from solid blocks of Unobtanium by Ipswich virgins.
Tom
Hi Tom
Thanks for the hints and links. I did know the modus shop.biz and I concur with your assessment. No need to save a few bucks by cutting holes yourself and messing up an otherwise valuable chassis. Since the shop is in Italy the shipping charges are also lower for us in Europe.
One more question regarding your boards. Do I remember this correctly, that with the current version of the Mod86, bridging is no longer advisable (poorer performance) and you therefore created the 286? It is therefore not longer possible to start out with the 86 and if more power would be require one would just add another 86 board?
I have currently the following startup / dc protection built into the above mentioned LM3886 monoblocks. https://audiocreativ.de/index.php?route=product/product&product_id=85
What do you think? Reuse it or does it more bad than good? Especially about the "sensor wire" running to output ground I am not sure about influence on performance. Although nothing detrimental is audible on my test speakers.
Thx
SH
The LM3886 does not have enough output current to be suitable for bridging with a 4 Ω load. You'll need three in parallel per side in the bridge to make that work. So you need six LM3886es to dance for you at low distortion in a bridge/parallel configuration. That's no small feat. It's also a sizeable BOM cost. Frankly, I think there are better, less expensive, and more efficient ways to get the output power you'd get from the bridged amp.
Some use output protection and a protection board like the one you show can be the ticket. Do note that some relays distort more than the MOD86/286. I don't know if the board you show uses such a relay. THD is generally not specified for power relays, so the only way to find out is usually to buy one and test it.
There were three primary reasons for the creation of the Modulus-286:
Tom
Some use output protection and a protection board like the one you show can be the ticket. Do note that some relays distort more than the MOD86/286. I don't know if the board you show uses such a relay. THD is generally not specified for power relays, so the only way to find out is usually to buy one and test it.
There were three primary reasons for the creation of the Modulus-286:
- Use of SMD components to allow for automated assembly.
- SMD components also allowed improved performance due to redesigned input section.
- Replacement for the Parallel-86, which used the two halves of an LM4780 to create a high-powered composite amp. Sadly TI discontinued the LM4780 over a year ago.
Tom
Got it. Thx.
Would you consider the KEFs R700, which are generally rated as 8ohm speakers, as a 4ohm load, because the impedance trops to ca. 3.2ohm at 145Hz as Anand has pointed out?
Thx
SH
Would you consider the KEFs R700, which are generally rated as 8ohm speakers, as a 4ohm load, because the impedance trops to ca. 3.2ohm at 145Hz as Anand has pointed out?
Thx
SH
I'd consider them 8 Ω drivers if they're specified as such. Some drivers have impedance dips well below the specified impedance, but those dips tend to be relative narrow so the total amount of power dissipated within that frequency range is limited. I wouldn't worry too much about it. 3.2 Ω is a pretty deep dip, though.
I build my amps to drive 4 Ω loads. I'm a build-once-and-forget kinda guy.
Tom
I build my amps to drive 4 Ω loads. I'm a build-once-and-forget kinda guy.
Tom
https://www.stereophile.com/content/kef-r700-loudspeaker-measurements
Looks like 4ohm to me. You do have the option of using 2 amps per speaker. Several options you could choose from. 4 mod-86, 2 mod-286 or a combination of both. You could even use 3 mod-286, 2 powering the lows and 1 split for each speaker for the highs.
Looks like 4ohm to me. You do have the option of using 2 amps per speaker. Several options you could choose from. 4 mod-86, 2 mod-286 or a combination of both. You could even use 3 mod-286, 2 powering the lows and 1 split for each speaker for the highs.
Hi Mark
That was my initial thought as well, start out with two Mod86s and when everything works out than add two more Mods86 and use the biamping possibility. However I understood that given the ca. 4 ohm impedance over a wide frequency range, the recommendation was to start with two Mod286.
What do guys think? Two 86 and expand to biamping or go for the two Mod286 without biamping?
Thx
SH
If you want a Modulus amp that can drive a 4 Ω load, I recommend:
Modulus-86 running on ±28 to ±30 V. 65 W into 4 Ω.
Modulus-286, mono running on ±35 to ±36 V. 100 W into 4 Ω.
The Modulus-286 does provide slightly better performance. Slightly lower THD and slightly lower noise than the Modulus-86.
For most applications, the two options are indistinguishable in performance (aside from the 65 W vs 100 W - which at ~2 dB is pretty small actually). If you are using high-efficiency drivers (think >90 dB @ 1 W, 1 m) the one parameter that might be meaningfully different between the two is the noise level. The Modulus-286 is considerably quieter.
In your application, it basically boils down to whether you want the latest&greatest, how much you're looking to spend up front, whether the 2 dB higher power, lower THD, and lower noise of the MOD286 is important enough to you, and whether you feel comfortable soldering SMD components.
Many find the MOD86 easier to build and you can start small and add channels later. The MOD286 is the better technical performer and if you're skilled in surface mount assembly, it's much faster and easier to assemble than the leaded components in the MOD86. Then again if you're NOT skilled in SMD assembly, you might want to pick up one of the $2 SMD practice kits from eBay before attempting the MOD286.
They're both good amps. In psychology what you're facing be referred to as an approach-approach conflict. Sadly, it's the one associated with the strongest post-decision cognitive dissonance (uneasy feeling). Grr... Humans!
Tom
Modulus-86 running on ±28 to ±30 V. 65 W into 4 Ω.
Modulus-286, mono running on ±35 to ±36 V. 100 W into 4 Ω.
The Modulus-286 does provide slightly better performance. Slightly lower THD and slightly lower noise than the Modulus-86.
For most applications, the two options are indistinguishable in performance (aside from the 65 W vs 100 W - which at ~2 dB is pretty small actually). If you are using high-efficiency drivers (think >90 dB @ 1 W, 1 m) the one parameter that might be meaningfully different between the two is the noise level. The Modulus-286 is considerably quieter.
In your application, it basically boils down to whether you want the latest&greatest, how much you're looking to spend up front, whether the 2 dB higher power, lower THD, and lower noise of the MOD286 is important enough to you, and whether you feel comfortable soldering SMD components.
Many find the MOD86 easier to build and you can start small and add channels later. The MOD286 is the better technical performer and if you're skilled in surface mount assembly, it's much faster and easier to assemble than the leaded components in the MOD86. Then again if you're NOT skilled in SMD assembly, you might want to pick up one of the $2 SMD practice kits from eBay before attempting the MOD286.
They're both good amps. In psychology what you're facing be referred to as an approach-approach conflict. Sadly, it's the one associated with the strongest post-decision cognitive dissonance (uneasy feeling). Grr... Humans!
Tom
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Tom thank you so much for the wonderful summary.
I start with two 286. Expect the order on Sunday when I am back home and have secure internet access. The SMD practice kit is already on its way and I bought a new 1.6mm solder tip for that purpose So I better get some good use out of it. If I later would decide to add another two 286 for biamping, maybe we can work out a small volume discount?
Thx
SH
I start with two 286. Expect the order on Sunday when I am back home and have secure internet access. The SMD practice kit is already on its way and I bought a new 1.6mm solder tip for that purpose
So I better get some good use out of it. If I later would decide to add another two 286 for biamping, maybe we can work out a small volume discount?Thx
SH
That's right. Tom has a nice diagram on his website of the pseudo-differential cable you are describing. Shield and neutral together on RCA end is correct.
As one who has THAT Line Driver too, I've got to say, I like it!
I built in stages, and I made a chassis with 3 THAT Line Driver boards and 3 Stereo DACs first, and made Mod86 amps later. I call it my "Preamp&DAC" that sits behind my Digital Signal Processor (my speaker's crossover is DSP between source and amp,....nothing but wire between amps and speaker drivers)
At any rate, I've never listened to my Mod86 without the THAT Driver boards, but when I was first using THAT board with my old amp, it deffinately gave it more drive.
