Just completed building an ACA v1.18 to go with my 2 plus year old ACA v1.16.
1. The ACA v1.18 does not make that sound heard through the speakers when you first turn it on, unlike the v1.16 which does.
2. The ACA v1.18 runs cooler than the v1.16 as a stand alone stereo amp.
3. But it runs much hotter then the v1.16 when used together in the Mono RCA Bridged configuration.
Can someone please tell me if these differences between the two amplifiers are typical, or not? If not, any suggestions on how to address?
Also, one of the v1.18 LEDs is slightly dimmer than the other.
Is this something I need to be concerned about?
Thank you for your consideration and any help you can offer.
Yours,
Michael
1. The ACA v1.18 does not make that sound heard through the speakers when you first turn it on, unlike the v1.16 which does.
2. The ACA v1.18 runs cooler than the v1.16 as a stand alone stereo amp.
3. But it runs much hotter then the v1.16 when used together in the Mono RCA Bridged configuration.
Can someone please tell me if these differences between the two amplifiers are typical, or not? If not, any suggestions on how to address?
Also, one of the v1.18 LEDs is slightly dimmer than the other.
Is this something I need to be concerned about?
Thank you for your consideration and any help you can offer.
Yours,
Michael
The LEDs differ due to the much lower current through them, no worry.
You can adjust one of the resistors if it bothers you.
List of all differences between V1.6 and V1.8:
You can adjust one of the resistors if it bothers you.
List of all differences between V1.6 and V1.8:
- Rear switch is a 3 position DPDT instead of 2 position, necessitating a change in wiring
- Rear panel is printed with a connection diagram
- Chassis rails are improved using weld nuts and secured by bolts
- Blade terminals are included for the front power switch
- Longer wire
- LED resistors have been changed from 10k to 33.2k to reduce LED brightness
Thank you for the reply.
The matter I'm most concerned with is the different operating temperatures between the v1.18 in stand alone stereo and Mono RCA Bridged configuration, wherein the v1.18 runs hotter than the v1.16.
Has anyone else encountered this occurrence?
Have not tried the Mono RCA Parallel configuration.
Thanks again
The matter I'm most concerned with is the different operating temperatures between the v1.18 in stand alone stereo and Mono RCA Bridged configuration, wherein the v1.18 runs hotter than the v1.16.
Has anyone else encountered this occurrence?
Have not tried the Mono RCA Parallel configuration.
Thanks again
Could your problem be operating a bridged amplifier with 4 ohm speaker loading?
Each channel would then "see" only 2 ohms.
Each channel would then "see" only 2 ohms.
To the best of my understanding my speakers are 8 ohm and pretty efficient, around 92 db.
Driving Hornshoppe Model 1 speakers (4 inch paper cone driver) with added Heil air motion driver.
I will check.
Thank you for mentioning this posibilty.
Driving Hornshoppe Model 1 speakers (4 inch paper cone driver) with added Heil air motion driver.
I will check.
Thank you for mentioning this posibilty.
The driver does seem to be 8 ohms.
But to a bridged amplifier that would be 4 ohms per channel.
The ACA does seem to struggle with 4 ohm loads.
Perhaps the parallel mono connection would be better with your speakers.
But to a bridged amplifier that would be 4 ohms per channel.
The ACA does seem to struggle with 4 ohm loads.
Perhaps the parallel mono connection would be better with your speakers.
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This is not unusual, many run into problems when bridging their amplifiers.
Few amplifiers are truly built for equal performance into both 8 ohms and 4 ohms.
Those that are built for that, have large and heavy power supplies (although toroid cores will help).
With the parallel connection, each channel's output current is halved compared to normal stereo.
Your amplifier sees 16 ohms instead of 8 ohms in the parallel connection.
And certainly not the 4 ohms you amplifier sees with the bridged connection.
Few amplifiers are truly built for equal performance into both 8 ohms and 4 ohms.
Those that are built for that, have large and heavy power supplies (although toroid cores will help).
With the parallel connection, each channel's output current is halved compared to normal stereo.
Your amplifier sees 16 ohms instead of 8 ohms in the parallel connection.
And certainly not the 4 ohms you amplifier sees with the bridged connection.
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Rayma is an expert. I am not. With that said...
I would check the PSUs between each amp. I think they went from 19V to 24V between V1.5 and V1.6, but it could not hurt to look. Both should be 24V and you should have configured each amp as such. Did you get full kits or source any of your own parts for either? What revision is your PCB for the 1.6?
Since they're 'Pure Class A' amps, each amp should actually cool a bit when playing music (particularly loudly). How are you measuring the temps? Could you post a few of the temps? It sounds like you have a pair of 1.6s and a pair of 1.8s correct? Alternatively, are you using one 1.6 and one 1.8 as the monoblocks when configured as mono RCA bridged? It seems odd to me that they'd behave differently when using two different configurations. It would seem that if one is running hotter... it would be the hotter running amp regardless of configuration (stereo vs. mono bridged) if using the same speakers etc.
Also, I don't think one of the LEDs should be noticeably dimmer than the other within the same amplifier (the 1.8). If they're truly that different, then it could be as simple as a stuffing error for the LED resistor on one board or your LED wiring. However, it might indicate an issue with one of your boards / the PSU wiring to one board.
Anyway... don't want to worry you, I'm just offering my
I agree, your observations are odd (to me). I'd have asked too. It's likely to be absolutely nothing just as Rayma surmised and everything will be dandy running in parallel mode.
If you're willing, would you post the temp differential between the 1.6 and the 1.8 in parallel. I'm just curious.
I would check the PSUs between each amp. I think they went from 19V to 24V between V1.5 and V1.6, but it could not hurt to look. Both should be 24V and you should have configured each amp as such. Did you get full kits or source any of your own parts for either? What revision is your PCB for the 1.6?
Since they're 'Pure Class A' amps, each amp should actually cool a bit when playing music (particularly loudly). How are you measuring the temps? Could you post a few of the temps? It sounds like you have a pair of 1.6s and a pair of 1.8s correct? Alternatively, are you using one 1.6 and one 1.8 as the monoblocks when configured as mono RCA bridged? It seems odd to me that they'd behave differently when using two different configurations. It would seem that if one is running hotter... it would be the hotter running amp regardless of configuration (stereo vs. mono bridged) if using the same speakers etc.
Also, I don't think one of the LEDs should be noticeably dimmer than the other within the same amplifier (the 1.8). If they're truly that different, then it could be as simple as a stuffing error for the LED resistor on one board or your LED wiring. However, it might indicate an issue with one of your boards / the PSU wiring to one board.
Anyway... don't want to worry you, I'm just offering my
I agree, your observations are odd (to me). I'd have asked too. It's likely to be absolutely nothing just as Rayma surmised and everything will be dandy running in parallel mode.If you're willing, would you post the temp differential between the 1.6 and the 1.8 in parallel. I'm just curious.
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The amp could be clipping, and so running hotter, in bridged mode.
Can you check to see if the temperature difference is still there, with no signal to the amps?
If not, clipping could be the reason. Or maybe this is just how the dynamic current source load works.
But I haven't ever seen or used one of these amps.
If, as you say, the bridged amp runs "much" hotter, I'd worry about oscillation, perhaps.
How did the parallel mono connection work out? Hopefully it will be cooler.
Can you check to see if the temperature difference is still there, with no signal to the amps?
If not, clipping could be the reason. Or maybe this is just how the dynamic current source load works.
But I haven't ever seen or used one of these amps.
If, as you say, the bridged amp runs "much" hotter, I'd worry about oscillation, perhaps.
How did the parallel mono connection work out? Hopefully it will be cooler.
"The amp could be clipping, and so running hotter, in bridged mode."
@rayma - Sorry to interrupt again, but I learn a ton from your posts.
If both amps are as they're supposed to be (electrically identical) and with the same heatsinks etc. then why would one clip and not the other? Why would one run hotter than the other?
@Cidermill - Don't want to hijack your thread. Rayma really is the expert. Just trying to learn alongside. Did I interpret correctly from post #1 that below is true... Ignore the actual numbers, just look to them as references as hotter than or cooler than. Last question... do they sound the same to you?
1.6 Stereo - 45C
1.8 Stereo - 40C (cooler than the 1.6 in stereo)
1.6 Bridged - 45C (no hotter than 1.6 running in stereo)
1.8 Bridged - 50C (much hotter than 1.6 in bridged)
To me... that indicates an oddity in assembly if both amps are not behaving the same way with the same signal and same speakers.
@rayma - Sorry to interrupt again, but I learn a ton from your posts.
If both amps are as they're supposed to be (electrically identical) and with the same heatsinks etc. then why would one clip and not the other? Why would one run hotter than the other?
@Cidermill - Don't want to hijack your thread. Rayma really is the expert. Just trying to learn alongside. Did I interpret correctly from post #1 that below is true... Ignore the actual numbers, just look to them as references as hotter than or cooler than. Last question... do they sound the same to you?
1.6 Stereo - 45C
1.8 Stereo - 40C (cooler than the 1.6 in stereo)
1.6 Bridged - 45C (no hotter than 1.6 running in stereo)
1.8 Bridged - 50C (much hotter than 1.6 in bridged)
To me... that indicates an oddity in assembly if both amps are not behaving the same way with the same signal and same speakers.
That is the question, and more data is needed on this. Without test equipment, you have to do observational tests.
Like whether the temperature difference is gone when the volume control is turned all the way down.
If so, then the difference is due to amplification, and are you sure the volume heard from the speakers
is exactly the same in all cases? (Not just the position of the volume control.)
Remember this a very unusual amplifier, with a dynamic current source load.
If the temperature difference persists even with no volume, it could be oscillation, or the circuitry behaving differently,
like differing bias currents, etc. But there isn't much detailed explanation available of exactly how these work.
Like whether the temperature difference is gone when the volume control is turned all the way down.
If so, then the difference is due to amplification, and are you sure the volume heard from the speakers
is exactly the same in all cases? (Not just the position of the volume control.)
Remember this a very unusual amplifier, with a dynamic current source load.
If the temperature difference persists even with no volume, it could be oscillation, or the circuitry behaving differently,
like differing bias currents, etc. But there isn't much detailed explanation available of exactly how these work.
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Its just two ACA amps.
One is v1.16 built about 2 1/2 years ago. Built from the complete kit, no parts substituted.
The other is the v1.18 completed about a week ago. Also just the stock kit. No augmentation.
Used the recommended solder, took my time; everything looks ok. Both amps have the DC balanced at 12.
Both amps sound fine and very similar when run one at a time in stereo mode. Both play the same volume, as best I can tell. Same for left and right channels.
Another question, if I may -
For the Parallel Mono configuration where should the two-way switch be on the v1.16 amp? Up for Mono?
One is v1.16 built about 2 1/2 years ago. Built from the complete kit, no parts substituted.
The other is the v1.18 completed about a week ago. Also just the stock kit. No augmentation.
Used the recommended solder, took my time; everything looks ok. Both amps have the DC balanced at 12.
Both amps sound fine and very similar when run one at a time in stereo mode. Both play the same volume, as best I can tell. Same for left and right channels.
Another question, if I may -
For the Parallel Mono configuration where should the two-way switch be on the v1.16 amp? Up for Mono?
Probably best to ask in this thread, to those who have designed and built it :
https://www.diyaudio.com/community/threads/amp-camp-amp-kit-1-6-1-8.256660/page-24
https://www.diyaudio.com/community/threads/amp-camp-amp-kit-1-6-1-8.256660/page-24