Nice small case. What size is it?
Very well ventilated for cool running.
When you said "it is only doing 100 -> 900 Hz"
Is it a middle range driver amplifier?
Very well ventilated for cool running.
When you said "it is only doing 100 -> 900 Hz"
Is it a middle range driver amplifier?
What will you do with the information?
I suggest you just accept that the output impedance is swamped by all the other impedances between the amplifier and the speaker driver and on the route back to the amplifier.
I suggest you just accept that the output impedance is swamped by all the other impedances between the amplifier and the speaker driver and on the route back to the amplifier.
I am surprised that no data appears. To "know" how it behaves with low frequencies. With 8 ohm (nominal) speaker.
Or the output impedance.
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Thank you!
The size is 182mm (7.25") deep, 70mm (2 3/4") tall. The faceplate is 19" x 3", the internal width is 15". It could've been a little bit wider.
It is the middle range driver amp. While driving 95 dB 8 ohm speakers the heatsinks are so close to room temp, I cannot even tell if it is on.
The case is held together with sixteen #6/32 bolts, all tapped into the heatsinks. A #6/32 bolt and washer holds the LM3886 to the heatsink. The toroid is held in place with a 1/4x20 bolt 2.5" long. The PCB's are mounted with a sandwich of washers, a 10mm long bolt and plastic standoffs.
All internal wiring is Southwire 14 AWG copper, the mic cables are Neotech, with only 75% shield coverage. These should probably be replaced with foil shielded mic cable.
I'm not sure what you mean by "of each module". The output impedance of the MOD86 R2.0 and PAR86 R1.0 is below 50 mΩ throughout the vast majority of the audio band. The DCR of the Thiele inductor dominates below 10 kHz. This would imply a damping factor >160 for 8 Ω and >80 for 4 Ω speakers, assuming you could somehow attach the speaker right at the amp output.
As Andrew correctly points out, the damping factor will be dominated by the impedance of connectors, cables, etc. I have no control over those.
Tom
There is some output impedance data in the original thread. But I think if you are looking at how interactive to loads the amplifier is, the numbers do not present the full picture.
Much bigger than what I thought I was looking at. Just goes to show how my eyes can be deceived and I jump to the wrong conclusion.
Still well ventilated though.
Hi Tom,
From a design perspective your amps look "technically awesome". I'm a horn guy lately so low noise floor is becoming increasingly important for me. What do you think about this pre being mated with your poweramps: RelaiXedSMD -- Documentation
Thanks, Maciej
From a design perspective your amps look "technically awesome". I'm a horn guy lately so low noise floor is becoming increasingly important for me. What do you think about this pre being mated with your poweramps: RelaiXedSMD -- Documentation
Thanks, Maciej
Hi Tom,
If one were to use Caddock MK132 resistors, would R3, R7, R8, R2 be the most likely candidates or are there other places to be considered? (R5/R9?)
Thanks!
If one were to use Caddock MK132 resistors, would R3, R7, R8, R2 be the most likely candidates or are there other places to be considered? (R5/R9?)
Thanks!
Darn!
When I plug in the tc electronic Konnekt 24D via 4 wire firewire connection, and the Gustard USB, I get a buzzing from the Modulus.
No buzzing from either the F5 or the AB international.... just the Modulus86.
The Konnekt 24D uses a switching wall outlet power supply. The buzzing happens even with the konnekt 24D off. It disappears when the switcher is unplugged from the back of the konnect 24D.
The switcher and laptop are both 25 ft from the modulus.
The Gustard AES converter is plugged into a Behringer stack of SRC/DEQ and DCX2496, the DCX with Jan Didden's mods. All are connected via AES/EBU.
Any ideas on how to get rid of this buzz would be most helpful. The konnekt 24D is used for providing the microphone input to REW. I'd like this not to be noisy. It is not noisy with the Marantz 250 in place -- that has just a two prong power cord.
Thanks!
When I plug in the tc electronic Konnekt 24D via 4 wire firewire connection, and the Gustard USB, I get a buzzing from the Modulus.
No buzzing from either the F5 or the AB international.... just the Modulus86.
The Konnekt 24D uses a switching wall outlet power supply. The buzzing happens even with the konnekt 24D off. It disappears when the switcher is unplugged from the back of the konnect 24D.
The switcher and laptop are both 25 ft from the modulus.
The Gustard AES converter is plugged into a Behringer stack of SRC/DEQ and DCX2496, the DCX with Jan Didden's mods. All are connected via AES/EBU.
Any ideas on how to get rid of this buzz would be most helpful. The konnekt 24D is used for providing the microphone input to REW. I'd like this not to be noisy. It is not noisy with the Marantz 250 in place -- that has just a two prong power cord.
Thanks!
Adding a ground loop breaker to the modulus did not do a lot. A little bit better.
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First off, would you quantity the buzzing? Are you talking actual buzzing (harsh, lots of harmonic content) or more of a hum (mostly single frequency)? What's the frequency of the buzz/hum/whatever?
Ground the input to the MOD86. Do you still have buzz/hum? If you do, you need to figure out why.
I've run the MOD86 in differential, single ended, and two-channel mono single ended configurations with no issues whatsoever. If you're having issues with the MOD86 itself, I'm suspecting a wiring error. There's no need for ground breakers or another hacks... 🙂
Once the MOD86 is hum/buzz free, proceed up the signal chain, step by step.
Tom
Ground the input to the MOD86. Do you still have buzz/hum? If you do, you need to figure out why.
I've run the MOD86 in differential, single ended, and two-channel mono single ended configurations with no issues whatsoever. If you're having issues with the MOD86 itself, I'm suspecting a wiring error. There's no need for ground breakers or another hacks... 🙂
Once the MOD86 is hum/buzz free, proceed up the signal chain, step by step.
Tom
Which Rev?
None of my circuits require special components. You'll be hard pressed to beat the performance of regular metal film resistors. It's your money, though...
Let's fix the hum/buzz issue first, though.
Tom
I revisited this, this morning. This is board rev 1.01
The ground loop breaker DOES work.
There is a very low level hum from the Modulus with the loop breaker installed and both the firewire and USB devices are connected to the laptop. Unplug or ground the input with the loop breaker installed and both USB/firewire connected and the amp is dead quiet.
Bypassing the ground loop breaker while both firewire and usb devices are plugged into the main laptop results in a buzzy HF hash and hum. Ground the input with the loop breaker bypassed both USB and firewire plugged in and the amp is dead quiet.
Yesterday, I mis-identified the source of the bulk of the 60 Hz hum that was left after the ground loop breaker was installed. Most of that is coming from the AB international amp. It has a ground lift switch that cures that issue.
The F5 also emits the HF part of the hash via the 105 dB efficient horn crossed over at 900 Hz, albeit at a very low volume. Unplug the input and the hash goes away.
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I'm not going to use Caddock, but PRP instead. They are 1/10th of the price, and I have used them in the past.
The ground loop breaker DOES work.
There is a very low level hum from the Modulus with the loop breaker installed and both the firewire and USB devices are connected to the laptop. Unplug or ground the input with the loop breaker installed and both USB/firewire connected and the amp is dead quiet.
Bypassing the ground loop breaker while both firewire and usb devices are plugged into the main laptop results in a buzzy HF hash and hum. Ground the input with the loop breaker bypassed both USB and firewire plugged in and the amp is dead quiet.
Yesterday, I mis-identified the source of the bulk of the 60 Hz hum that was left after the ground loop breaker was installed. Most of that is coming from the AB international amp. It has a ground lift switch that cures that issue.
The F5 also emits the HF part of the hash via the 105 dB efficient horn crossed over at 900 Hz, albeit at a very low volume. Unplug the input and the hash goes away.
----------
I'm not going to use Caddock, but PRP instead. They are 1/10th of the price, and I have used them in the past.
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I'm not a fan of loop breakers. Just saying... 🙂
Do you have hum when the laptop is running on battery power?
It sounds like the rest of your issues were caused by other pieces in the signal chain and that the MOD86 is working for you. That's good to hear.
Tom
Do you have hum when the laptop is running on battery power?
It sounds like the rest of your issues were caused by other pieces in the signal chain and that the MOD86 is working for you. That's good to hear.
Tom
Yes, the low level hum is still present on battery power too.
The other bits in the chain are all Behringer: DCX2496 (Jan Didden mods), DEQ2496, SRC2496, and Gustard XMOS USB/AES conversion.
The volume of the noise does not change as the volume is turned up.
I am a little suspicious of the 75% shielding on the mic cable I used for input wiring.
The other bits in the chain are all Behringer: DCX2496 (Jan Didden mods), DEQ2496, SRC2496, and Gustard XMOS USB/AES conversion.
The volume of the noise does not change as the volume is turned up.
I am a little suspicious of the 75% shielding on the mic cable I used for input wiring.
It could be one of the other pieces of gear that hums. If you feed hum to the input of the MOD86, it will be amplified...
I doubt your mic cable is causing hum. I bet there's a ground loop somewhere. If you draw a schematic (include interconnects, data, and power cords) we can probably find it.
Tom
I doubt your mic cable is causing hum. I bet there's a ground loop somewhere. If you draw a schematic (include interconnects, data, and power cords) we can probably find it.
Tom