Connecting multiple portable amps? Is this heresy?
Mar 9, 2021 at 12:38 PM Thread Starter Post #1 of 15

Knee Deep In Epoxy

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So I'm relatively new to this hobby (less than a year in). I'm trying all sorts of combos.

Is this allowed? Or am I gonna burn something?

Spoiler it sounds great!


IMG_20210309_170845.jpg


We have a BTR5 connected via LDAC to my android phone which is on max volume. The BTR5 is on high gain, max volume and is connected via a balanced 2.5mm to 3.5mm patch cable (from Hart Audio) to the 3.5mm "line in" on the Monolith THX Portable. The Monolith is outputting the whole signal (using a balanced cable) to hungry t60 Argons at around 1 o-clock (-4db). Any higher is too loud for me.... In theory the Monolith portable shouldn't be able to power Argons but this seems like more than enough.

I have no idea what is going on in terms or current or signal and whether I am risking damaging the Monolith by putting too much signal though it, or getting a less than optimal sound because there are too many pieces in the chain.

Curious to hear the thoughts of any other mad scientists out there trying similar combinations and the thoughts of anyone who thinks this is a bad idea (if so why?)
 
Mar 9, 2021 at 12:53 PM Post #2 of 15

Barusu Lamperouge

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It should not be a problem of you are using BTR5 as a DAC and not an amp. But it seems that you are using two amps in succession, so there are chances of something going awry if your gear is not in sync or complementing each other in terms of voltage and power. I'd rather avoid doing this to protect the gear from damage.
 
Mar 9, 2021 at 1:23 PM Post #3 of 15

OspreyAndy

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I assume that you are doing this because the BTR5 have not enough juice to power your cans to the full dynamic yes? BTR5 acting as Analogue LO then it will be better served with SE output from the 3.5mm at max volume rather than using the balanced 2.5mm output which you force to SE anyway upon entering the amp. In the longer run I would rather revamp my source/DAC/amp source to match my cans better, a safer route
 
Mar 9, 2021 at 3:07 PM Post #4 of 15

Knee Deep In Epoxy

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I assume that you are doing this because the BTR5 have not enough juice to power your cans to the full dynamic yes? BTR5 acting as Analogue LO then it will be better served with SE output from the 3.5mm at max volume rather than using the balanced 2.5mm output which you force to SE anyway upon entering the amp. In the longer run I would rather revamp my source/DAC/amp source to match my cans better, a safer route

It should not be a problem of you are using BTR5 as a DAC and not an amp. But it seems that you are using two amps in succession, so there are chances of something going awry if your gear is not in sync or complementing each other in terms of voltage and power. I'd rather avoid doing this to protect the gear from damage.
Need to check if the BTR5 can be used just as a DAC. Thanks!
 
Mar 9, 2021 at 3:14 PM Post #5 of 15

Knee Deep In Epoxy

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I assume that you are doing this because the BTR5 have not enough juice to power your cans to the full dynamic yes? BTR5 acting as Analogue LO then it will be better served with SE output from the 3.5mm at max volume rather than using the balanced 2.5mm output which you force to SE anyway upon entering the amp. In the longer run I would rather revamp my source/DAC/amp source to match my cans better, a safer route

I'm doing it for a few reasons -

1. the Monolith doesn't have Bluetooth. Sometimes the convenience of BT wins out over going wired into the Monolith (which has both digital usb and 3.5mm inputs).

2. As you said... The juice... the Argons require a lot of power. Somehow this manages to snowball enough to make it very listenable with headroom. But if I'm risking damage I'll definitely reconsider.
 
Mar 10, 2021 at 7:27 AM Post #6 of 15

technobear

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In this case you are fine. The maximum output voltage of the BTR5 won't trouble the Monolith in the slightest.
 
Mar 10, 2021 at 8:03 AM Post #7 of 15

ClieOS

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We have a BTR5 connected via LDAC to my android phone which is on max volume. The BTR5 is on high gain, max volume and is connected via a balanced 2.5mm to 3.5mm patch cable (from Hart Audio) to the 3.5mm "line in" on the Monolith THX Portable. The Monolith is outputting the whole signal (using a balanced cable) to hungry t60 Argons at around 1 o-clock (-4db). Any higher is too loud for me.... In theory the Monolith portable shouldn't be able to power Argons but this seems like more than enough.

I have no idea what is going on in terms or current or signal and whether I am risking damaging the Monolith by putting too much signal though it, or getting a less than optimal sound because there are too many pieces in the chain.

Curious to hear the thoughts of any other mad scientists out there trying similar combinations and the thoughts of anyone who thinks this is a bad idea (if so why?)

First of, it is not heresy to do double amping - at worst, you might make the SQ worst. But more then often, double amping can be a practical, quick-and-easy solution to add a bit more volume or power to otherwise under-powered system. Of course, the proper way to add power is still just has a more powerful single stage amplification. However, sometime you have to work with what you have at hand.

THAT BEING SAID...

I see a HUGE problem in your setup: "....The BTR5 is on high gain, max volume and is connected via a balanced 2.5mm to 3.5mm patch cable (from Hart Audio) to the 3.5mm "line in" on the Monolith THX Portable..."

As far as I known Monolith THX Portable only has a single-ended input - that means you are using a (*stupid) cable the short-circuit the BTR5 balanced output to feed into the Monolith THX Portable. In worst case when the balanced output has no current limiting protection, it would have instantly burnt out the balanced output circuit. But luckily for your, BTR5's balanced output does seems to have protection circuit and therefore it doesn't get burnt out right away - but it still means you are slowly over-loading / over-heating the output circuit. That means you are actively shortening the lifespan of your BTR5's balanced output and at some point in the future it might suffer a premature death. The fact that you are maxing out the BTR5's balanced output is NOT helping either, since it also means it is also short-circuiting at max. I'll urge you to stop trying to kill off your gears as much as possible. If you still want to double amp, use BTR5's single-ended output instead.
 
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Mar 10, 2021 at 8:32 AM Post #8 of 15

eskamobob1

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First of, it is not heresy to do double amping - at worst, you might make the SQ worst. But more then often, double amping can be a practical, quick-and-easy solution to add a bit more volume or power to otherwise under-powered system. Of course, the proper way to add power is still just has a more powerful single stage amplification. However, sometime you have to work with what you have at hand.

THAT BEING SAID...

I see a HUGE problem in your setup: "....The BTR5 is on high gain, max volume and is connected via a balanced 2.5mm to 3.5mm patch cable (from Hart Audio) to the 3.5mm "line in" on the Monolith THX Portable..."

As far as I known Monolith THX Portable only has a single-ended input - that means you are using a (*stupid) cable the short-circuit the BTR5 balanced output to feed into the Monolith THX Portable. In worst case when the balanced output has no current limiting protection, it would have instantly burnt out the balanced output circuit. But luckily for your, BTR5's balanced output does seems to have protection circuit and therefore it doesn't get burnt out right away - but it still means you are slowly over-loading / over-heating the output circuit. That means you are actively shortening the lifespan of your BTR5's balanced output and at some point in the future it might suffer a premature death. The fact that you are maxing out the BTR5's balanced output is NOT helping either, since it also means it is also short-circuiting at max. I'll urge you to stop trying to kill off your gears as much as possible. If you still want to double amp, use BTR5's single-ended output instead.


This ^^^^^ i can't believe no one has said it yet. Going from a balanced source -> an unbalanced input is a massive nono

If you just switch over to 3.5 out of the btr5 you will be fine though. Maybe some loss of sq from double amping, but it won't be major compaired to the gained convenience
 
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Apr 8, 2021 at 3:18 AM Post #10 of 15

Knee Deep In Epoxy

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Another thought/question has occurred to me about my setup and that is on the headphone side...

I'm using T60 Argons which according to Mod House should need at least 1w @ 50Ω ... Combined output power pictured above would be no more than 420mw @ 32Ω yet I'm still able to reach loud volume with with around 30% of headroom to spare on the Monolith.

How can I tell if they Argons are underpowered and am I slowly damaging them too?

I don't think I'm hearing any clipping or distortion... (I'm assuming it would be obvious if I was).
 
Apr 8, 2021 at 4:09 AM Post #11 of 15

technobear

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If it's this one...

https://www.monoprice.uk/products/m...ogy-analog-input-slim-design-dirac-sensaround

then the maximum output of that Monolith appears to be 340mW single ended into 32 ohms. Don't know where you are getting 420mW from. You can't add the BTR05. That is contributing an input signal only and will have no effect on the maximum that the Monolith can deliver.

If it's loud enough and has headroom to spare then you do not need more. You are not damaging the headphone. If you do try to play louder than the Monolith can deliver, you will hear it. The sound will become coarse and very tiring to listen to but it won't damage the headphone unless you seriously overdo it.
 
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Apr 8, 2021 at 4:24 AM Post #12 of 15

Knee Deep In Epoxy

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If it's this one...

https://www.monoprice.uk/products/m...ogy-analog-input-slim-design-dirac-sensaround

then the maximum output of that Monolith appears to be 340mW single ended into 32 ohms. Don't know where you are getting 420mW from. You can't add the BTR05. That is contributing an input signal only and will have no effect on the maximum that the Monolith can deliver.

If it's loud enough and has headroom to spare then you do not need more. You are not damaging the headphone. If you do try to play louder than the Monolith can deliver, you will hear it. The sound will become coarse and very tiring to listen to but it won't damage the headphone unless you seriously overdo it.
I got 420 by adding the BTR5 output (as you figured out)... But if it doesn't work that way then yes, it's 340mW, which makes it even more surprising that the Argons get so loud with a lot of headroom... Good to know I won't be damaging them...but still very confusing to experience given all the talk about the low sensitivity of Argons and everyone saying they need "a lot" of power...

Thanks for clarifying!
 
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Apr 8, 2021 at 6:00 AM Post #13 of 15

technobear

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There is a lot of nonsense talked on these forums and elsewhere about how much power is needed to drive this or that headphone. If any of these people are actually using all that power, they can expect permanent hearing damage in short order.
 
Apr 8, 2021 at 10:40 PM Post #14 of 15

ClieOS

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I think it is worth noting that power and volume is not the same thing.

Power = voltage * current. Voltage is what directly responsible for volume. Turn the volume knob up and you will increase the output voltage - while it also increases the output power in general, it doesn't necessary always make it better. As at some point, your amp's (or source"s) output current might run out before the volume knob is turned all the way up, then it usually will result in distortion start going up (where the amp is trying to push out more current that it doesn't have), actually decreasing the SQ the more volume you go. In audio measurement, we usually define the output power of the device using the the maximum voltage and current of the device can push out when the distortion reaches 1% with a 32 ohm load (or 10% for loudspeaker / power amp test in some places). Since testing for power usually only involves simple pure test tone, it is also considered a good practice that you have 2~3 times the power requirement for any particular headphone in real world as reserved power, given music is not simple pure tone but complex multi-tone. That way it is unlikely you will ever going to stress the output device at any given point and thus the headphone will sounds as consistent and tightly controlled as possible. While all of the above is good in theory, it is not easy to actually know just how much power is considered enough when you don't have the expensive equipment to test the output device with headphone, so the easy way is just to use a source that is generally a bit more powerful than it is probably needed. A good old way of doing this is to use a source that you can keep the volume knob around (more or less) 12 o'clock position - of course it is not precise this way, but it is consider a safer choice
 
Apr 9, 2021 at 10:38 AM Post #15 of 15

Knee Deep In Epoxy

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I think it is worth noting that power and volume is not the same thing.

Power = voltage * current. Voltage is what directly responsible for volume. Turn the volume knob up and you will increase the output voltage - while it also increases the output power in general, it doesn't necessary always make it better. As at some point, your amp's (or source"s) output current might run out before the volume knob is turned all the way up, then it usually will result in distortion start going up (where the amp is trying to push out more current that it doesn't have), actually decreasing the SQ the more volume you go. In audio measurement, we usually define the output power of the device using the the maximum voltage and current of the device can push out when the distortion reaches 1% with a 32 ohm load (or 10% for loudspeaker / power amp test in some places). Since testing for power usually only involves simple pure test tone, it is also considered a good practice that you have 2~3 times the power requirement for any particular headphone in real world as reserved power, given music is not simple pure tone but complex multi-tone. That way it is unlikely you will ever going to stress the output device at any given point and thus the headphone will sounds as consistent and tightly controlled as possible. While all of the above is good in theory, it is not easy to actually know just how much power is considered enough when you don't have the expensive equipment to test the output device with headphone, so the easy way is just to use a source that is generally a bit more powerful than it is probably needed. A good old way of doing this is to use a source that you can keep the volume knob around (more or less) 12 o'clock position - of course it is not precise this way, but it is consider a safer choice
This is great info. Thanks for taking the time to explain. The ±12 o'clock rule is a nice and easy rule of thumb.
 

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