86 2.1 build problem …. Help!
Hi all. I’m building up a pair of 86 2.1 boards. I powered up the first board and checked the 15V supplies. +15 is a little over 16V ( a little high for my liking) but the -15 is +13 and it’s regulator is getting hot.
I’ve doubled checked all polarized caps, diodes and the regulators to make sure they’re in correctly and they are. I’ve checked all the solder joints under a magnifier and there aren’t any shorts. I tried to be very careful installing all the components but obviously something is very wrong.
Does anyone have any ideas where to start looking? Thanks
Hi all. I’m building up a pair of 86 2.1 boards. I powered up the first board and checked the 15V supplies. +15 is a little over 16V ( a little high for my liking) but the -15 is +13 and it’s regulator is getting hot.
I’ve doubled checked all polarized caps, diodes and the regulators to make sure they’re in correctly and they are. I’ve checked all the solder joints under a magnifier and there aren’t any shorts. I tried to be very careful installing all the components but obviously something is very wrong.
Does anyone have any ideas where to start looking? Thanks
I can't guarantee that all 300 VA transformers will fit in all 2U chassis. All I know is that in the two amps I built that way the transformer fit just fine.
As always: Check the dimensions with the manufacturers before buying.
Tom
From Page 21 of the Modulus-86 Rev. 2.1 documentation:
So +16 V is fine for the positive regulator. You get more headroom, thus lower THD, on the LME49710 and THAT1200 when you run closer to the maximum allowed ±18 V.
Now a positive voltage out of the negative regulator is definitely broken. Let's figure out why.
I suggest checking the polarity on D9, D10, D11, and D12. If those are all installed correctly, my best guess at this point is that you have a solder bridge between D1 and D6. The two low-voltage supplies join there.
A common build error on the Rev. 2.1 (which led to the spin to Rev. 2.2) is that the LME49710HA is mounted 45º off. On the TO-99 metal can package, Pin 8 is marked - unlike all other packages where Pin 1 is marked.
On the PCB, pin 8 is marked by a corresponding tab on the package outline drawing on the top silk screen. Pin 1 is marked by a square pad (which may have led to some of the confusion).
If this indeed the issue in your case, you'll need to replace the LME49710HA. Once you get the part de-soldered from the board, I suggest verifying that the ±17 V regulators work as designed before plugging in the new LME49710HA.
If this does not get you going, toss me an email (tomchr@neuro...) with a picture of both the top and bottom of your boards. I'll help you out.
Tom
Last edited:
RockSteady40 uses Rev. 2.1 boards. They take the TO-99 can (LME49710HA).
Rev. 1.x, 2.0, and 2.2 all use the 8-pin DIP (LME49710NA).
The differences between the different revisions are outlined here: Post #3775.
Tom
Rev. 1.x, 2.0, and 2.2 all use the 8-pin DIP (LME49710NA).
The differences between the different revisions are outlined here: Post #3775.
Tom
Last edited:
Thanks, Tom.
I placed a backorder today for 20 of the LME49710NA in DIP8 layout from Mouser. Just wanted to make sure I ordered the right ones. Should get them next month. Once I get them I will place an order for some Mod-86 boards. Plan to do a 4-channel build for some LX-minis. The rest are for some THAT driver boards.
I placed a backorder today for 20 of the LME49710NA in DIP8 layout from Mouser. Just wanted to make sure I ordered the right ones. Should get them next month. Once I get them I will place an order for some Mod-86 boards. Plan to do a 4-channel build for some LX-minis. The rest are for some THAT driver boards.
Even if the transformer manufacturer's specifications, and the inside dimensions of the enclosure manufacturer's specifications indicate that the transformer will fit with *some* clearance, it's important to either determine or use a stiff bottom and top plate (assuming conventional mounting) so that flexing of either won't result in a shorted turn (typically, the top enclosure sheet or plate touches the top of the transformer mounting bolt when flexed).
A non-conductive material adhered to the top plate above the transformer is also a good precaution if the stiffness is unknown prior to examination (such as when ordering sight unseen from a website) and you discover that there is too much flex once it's actually in your possession.
Standard rackmount U-size enclosures (which may be 19" rack width, or 17" without rack ears, or less but not more) are external dimensions, and reflect the height of the rackmount front plate, not the actual enclosure, so it's impossible to say with certainty what the inside dimension of an xU enclosure will be, if not specified. Generally speaking you will have the largest inside dimension / space if the top and bottom plate material is mild steel vs aluminum, although thin aluminum might be too flexible (shorted turn, again).
If you can get good images of an enclosure you are considering, you might choose one where the top and/or bottom plate(s) mount in such a way that spacers of extruded or flat metal could be used to increase clearance should it prove necessary, assuming it's not intended to be actually mounted in a standard rack.
Last edited:
Very true. Having the top plate touch the top of the mounting bolt of the transformer turns your audio amplifier into a spot welder. Then the fuse blows.
Definitely a good recommendation. A piece of acrylic or similar would work well, if you can get the glue to stick on it.
I usually buy the transformer before I buy the chassis. That way I can measure it to get an idea of how well it'll fit. Also note that some of the cheaper transformers - such as the Antek ones - aren't all that well specified on their mechanical dimensions. I often find that the posted dimensions may be reasonably accurate for the core and windings but will often exclude wire exits and mounting hardware. I'd trust Hammond's specs to a greater extent, but they're quite a bit more expensive than the Antek transformers.
Tom
I would tame my room before adding subwoofers. With my current setup and taste in music, I don't see any need for subs. If you have a good room and you enjoy music with a lot of detail in the bass, you'll probably benefit from adding a sub or from something like the SL Orion or LX521.4.
Tom
Tom
Hi All, Been a long time since I've posted anything. Just working a lot, and listening to music. I too have LX Minis with Mod86 -Love it! You will not be disappointed.
Some comments in regards to bass. I built mine in stages. Built LX Minis first, and then Mod86 next. Initially I was using a HT Receiver to get multiple channels to drive LX Minis. After completing 4 channels Mod86 and ditching the ol'reciever my first impression was that the bass was better.
Even still I added subs after that. I'm a fan of the Davies Sub plan on the OPLUG Forum. Seemed like they didn't cost too much (compared to others), and if you're a member with receipt of Linkwitz plans, Dave will give you the DSP-File to integrate them perfectly with the LX Minis.
The file does not high-pass the LX Minis, only puts a curve on the low end to make the LX Mini roll off 20hz at the same rate as Sub. We all know LX-Minis way far below f3 at 20 he, but It's about blending right? I would say it's not as much of a sub as it just makes the LX mini a nice balanced 3-way. The subs do add just a little to the bottom end. On many songs I can't even tell that they're on (they are not overbearing), and on other songs it becomes apparent that there's another octave below the LX-Minis.
So do LX Minis with Mod86 "need" subwoofer? No. Might you enjoy it if you added subs (and two more channels of Mod86). Probably.
I have played around, and high passing the LX Minis at 60 or 100 can make the whole thing play louder without over excursion of LX mini woofers, but that volume level is not necessary, unless you're trying to listen from down the street.
I've heard other systems where people add a subwoofer, and it sounds unnaturally bassy or boomy. Might be good for movies or rapp music, but not my cup of tea.
On my set up, Dire Straights and Dave Brubeck have just th right amount of punch in the drums, and also Cello strings sound full but not too much.
Sorry to be off topic. Just got a little excited reading about someone else building LX Minis with Mod86. Its such a perfect match!
Some comments in regards to bass. I built mine in stages. Built LX Minis first, and then Mod86 next. Initially I was using a HT Receiver to get multiple channels to drive LX Minis. After completing 4 channels Mod86 and ditching the ol'reciever my first impression was that the bass was better.
Even still I added subs after that. I'm a fan of the Davies Sub plan on the OPLUG Forum. Seemed like they didn't cost too much (compared to others), and if you're a member with receipt of Linkwitz plans, Dave will give you the DSP-File to integrate them perfectly with the LX Minis.
The file does not high-pass the LX Minis, only puts a curve on the low end to make the LX Mini roll off 20hz at the same rate as Sub. We all know LX-Minis way far below f3 at 20 he, but It's about blending right? I would say it's not as much of a sub as it just makes the LX mini a nice balanced 3-way. The subs do add just a little to the bottom end. On many songs I can't even tell that they're on (they are not overbearing), and on other songs it becomes apparent that there's another octave below the LX-Minis.
So do LX Minis with Mod86 "need" subwoofer? No. Might you enjoy it if you added subs (and two more channels of Mod86). Probably.
I have played around, and high passing the LX Minis at 60 or 100 can make the whole thing play louder without over excursion of LX mini woofers, but that volume level is not necessary, unless you're trying to listen from down the street.
I've heard other systems where people add a subwoofer, and it sounds unnaturally bassy or boomy. Might be good for movies or rapp music, but not my cup of tea.
On my set up, Dire Straights and Dave Brubeck have just th right amount of punch in the drums, and also Cello strings sound full but not too much.
Sorry to be off topic. Just got a little excited reading about someone else building LX Minis with Mod86. Its such a perfect match!
Yes, it does remove the low-frequency boost from the LXmini speakers. It also adds a 20Hz HP filter which eases excursion a bit further and also helps phase-matching with the sub-woofers.
The sub-woofers themselves are a simple, closed-box setup using Peerless 830668 drivers. So, very easy to add on to the existing LXmini scheme with minimal cost. Much less than the LXmini+2 dipole setup.
Dave.
I thought an open baffle sub might be good to pair with the LX-minis, but the SL dipole subs are fairly expensive. I was going to try the LX-minis without sub first. At some point I may try the GR-research OB servo subs, but they also cost a bit. Looking forward to the LX-minis and the Mod-86 amp. I will be using the Hypex DLCP for DSP feeding it from a Tortuga Preamp, from either phono input or digital from a Raspberry Pi to Soekris Dam-1021 DAC.
WCWC,
Re:Tortuga LDR.
See here for the eye opener:
Tortuga Audio LDR3 Volume Control: Measurements & Review
Don’t shoot the messenger. Facts are facts. Given that you are considering the excellent Modulus 86, please also consider a better designed preamp to go with it!
Best,
Anand.
P.S. Tom - Sorry for the off topic post.
Re:Tortuga LDR.
See here for the eye opener:
Tortuga Audio LDR3 Volume Control: Measurements & Review
Don’t shoot the messenger. Facts are facts. Given that you are considering the excellent Modulus 86, please also consider a better designed preamp to go with it!
Best,
Anand.
P.S. Tom - Sorry for the off topic post.
Anand,
I read the post a while ago. I already have the board so I am going to try it out. I already listened to the demo unit with my existing ACA amps and I thought it sounded fine. The speakers may sound better with the DLCP acting as a preamp. If that is the case I will have to get the DLCP control module for volume control and sell the Tortuga board. I will also try using THAT driver/receiver boards to make a preamp since I will have them.
I read the post a while ago. I already have the board so I am going to try it out. I already listened to the demo unit with my existing ACA amps and I thought it sounded fine. The speakers may sound better with the DLCP acting as a preamp. If that is the case I will have to get the DLCP control module for volume control and sell the Tortuga board. I will also try using THAT driver/receiver boards to make a preamp since I will have them.