Skylar88, that's similar to changing resistor values on the Objective 2 headphone amp.
I know that's a headphone amp, and I can see that the Lender is a preamp, but how does the Objective 2 shape up against the Lender when used as a preamp, in your opinion, specifically with the ACA?
Thanks.
I have no experience with the Lender, although I really want to build one.
I can attest that the O2 makes a simply wonderful preamp.
Thanks 6L6, I was wondering if I was building the wrong preamp as the talk here had gone along the lines of the preamp making or breaking the quality of performance of the ACA.
Hi yes I removed everything upstream and swapped the speaker cables and it is definitely the left channel of the ACA. I have tested all other components.
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exw9, I would look for dry joints with the wooden stick approach.
I have found over the years that there are various degrees of dry joints (some not making contact at all, some all but fully contacted) admittedly, this has not been in audio, but pcb repair on heating boilers.
I would look at the end of the train first ie. amp to speakers and work backwards.
But I'm just a novice, so trying to help
I have found over the years that there are various degrees of dry joints (some not making contact at all, some all but fully contacted) admittedly, this has not been in audio, but pcb repair on heating boilers.
I would look at the end of the train first ie. amp to speakers and work backwards.
But I'm just a novice, so trying to help
It's in the kit chassis from the diyAudio Store, which has top and bottom vents. It's running at 126F on the heat sinks and 110F inside the box now that the ambient temp is dropping.
I'll add taller feet, though, and check the temp again. Seems like I should start preparing for the summer.
Thanks for the tips!
Semiroundel, the Objective 2 was on my short list of preamps last year for use with the ACA, but then I decided to build the B1. Thus, I wouldn't know how it compares with the AKSA Lender pre.
What I can tell you is that I was pretty happy with the B1 until now with most of my music, except for the older Pink Floyd stuff (recorded at lower level than is done currently) and classical music. The B1 doesn't have gain (arguably needed for the ACA), but the sound quality is very good, being a Pass design.
Now, if you'd ask me how the AKSA Lender is shaping up against the B1, I'd have to tell you that I prefer the AKSA Lender for it's better soundstage imaging and layering. The AKSA Lender is quite new and wasn't available when I started my preamp short list in July 2017. I believe the PCB's became available around Nov/Dec 2017.
Was not the Lender offered only(?) as a DIY Audio group buy a year or so ago, the first batch of which sold out? Might be a project for the DIY Audio store to consider offering to those folks needing a bit of grunt to drive their ACAs? If a low powered Class A amp can be powered by an inexpensive laptop brick SMPS, why not a pre-amp such as this? That’d certainly simplify the construction and keep its chassis form factor tiny.
Skylar, what would you estimate the chassis dimension requirements to be on your Lender, if the power supply was external? I’m thinking that something like a Galaxy 2U 230x230mm would nicely complement the ACA’s size.
Skylar, what would you estimate the chassis dimension requirements to be on your Lender, if the power supply was external? I’m thinking that something like a Galaxy 2U 230x230mm would nicely complement the ACA’s size.
@exw9. Sorry to be beating a seemingly dead horse but since you have had the amp working just fine for months and now you are detecting one channel is running weaker than the other, I wonder if you may have suffered heat damage to one of your electrolytic caps. If this is the case you will need both to replace the damaged component and get better ventilation.
The 25mm + rubber feet for the amp case might be difficult to find. It might be easier to get aluminum or wood feet, or an isolation combo with a base and a cone-shaped foot that goes into the base.
The 25mm + rubber feet for the amp case might be difficult to find. It might be easier to get aluminum or wood feet, or an isolation combo with a base and a cone-shaped foot that goes into the base.
Thanks oc11, this is really helpful! and definitely not a dead horse, still trying to figure this thing out. Is there a way i can measure the caps to find out if i have cooked one?
The PCB's for the Aksa Lender SE Class A Preamp is still available from XRK Audio.
The chassis dimensions on mine is 225 wide x 175 deep x 70 high. One can probably knock 75mm off the width if it doesn't have to house a power supply. It will easily fit into the U2 chassis.
Now that we're talking about preamps for the ACA; It reminds me of the day a friend brought along a Pocket Class A Headphone Amp, also from XRK Audio. We hooked it up as preamp for the ACA. It was the best sound I ever heard coming from my ACA, for it was sweet, musical and wonderful. I've never heard the M2, but I imagine the sound must have been very similar to that of the M2.
@exw9. I am not an electrical engineer or circuit guy. The information I provided came from this post to heat damage to electrolytic capacitors (this is the link heat - Hot capacitors: Is that a problem? - Electrical Engineering Stack Exchange ):
"I'll assume that these are power supply capacitors.
Short answer:
45C is tolerable.
Cooler would be better.
Taking steps to minimise temperature will improve lifetime, especially in a continuously on application.
All similarly specified capacitors are not created equal. Brand may matter.
Long! answer:
That's hotter than you'd expect in a simple power supply circuit, but should be tolerable - but see below re operating lifetime that you can expect. "Rule of thumb" is that capacitor life halves for every 10 degrees C rise in temperature. If your capacitors are ~ 45C externally assume that the core is at say 55C. That's (105-55) = 50C lower than rated so lifetime will be about 2^5 = 32 times longer than nominal rating. Most capacitors (especially 105C rated ones) have a 2000 hour or better rating so you could expect a lifetime of about 2000 x 32 = 64000 hours or about 8 years of continuous operation. Even if core temperature was 65C that would give 4 years continuous. If the modem is run 24/7, as it may well be, then capacitor failure in the say 2 to 10 year timescale is not unexpected. What lifetime did you get from the original capacitors? And was the modem operated continuously?
Capacitors are also rated for "ripple current" and exceeding the ripple current rating will increase internal heating and reduce lifetime. This is an additive effect with temperature. eg If two capacitors are operating at 50C then the one with a larger ripple current will have a shorter lifetime. Formulae are available to allow ripple current lifetime derating calculations (not to hand at present, I can provide if useful).
Ripple current ratings can vary widely between capacitor model and manufacturer. Using a known reputable brand of capacitor is recommended in demanding applications as specification sheets for unknown brands are often suspect, often having been copied from those of other manufacturers. [[This claim is based on my having personally tracked down the source of a significant number of data sheets of capacitors and other products when the claims did not seem to match reality. Internet searching on an unusual phrase will often allow the source to be located.]]
Operating your modem without its case is liable to reduce capacitor operating temperature and increase lifetime. Anything else you can sensibly do to reduce ambient temperature will also help. If you measure a 45C cap temperature in a 20C ambient room, if you then operate the modem in a 30C enclosure the cap temperature will probably be 55C or higher.
Fan cooling may make sense. But just replacing the caps when they fail or buying a new modem may be preferable. Heatsinks for capacitors are not unknown but are not common. Anything you can do to sensibly improve airflow will help. eg if it has no case then orientation may not matter much, so orienting it to improve air flow may be possible.
A datasheet or manufacturer's information should tell you
Rated operating temperature.
Lifetime at rated temperature.
Ripple current.
ESR (less commonly)
If they don't tell you the first three, buy another brand. ESR is important but is reasonably well correlated with the other parameters. You can buy capacitors with 3000 hour or 5000 hour or even longer lifetimes at rated temperature, but cost is liable to be higher to much higher. You can buy capacitors with higher than 105C temperature ratings but they are usually much less common and probably expensive.
There are many well known & reputable brands. Panasonic make a wide range of grades, generally seem to "know their stuff" and often are not much dearer than little known or unknown brands. They are certainly not the only brand to consider but are a good starting place.
Distributors like Digikey (DigiKey Electronics - Electronic Components Distributor) stock a vast range of brands and models. Digikey have an excellent parametric search engine that allows you to selectively subset based on many different parameters. Even if you buy elsewhere their product search engine is a useful tool. Also see FindChips: Electronic Components, Distributor Inventories, Datasheets [[No association with Panasonic or Digikey apart from being a satisfied user and customer/ database user.]]
shareimprove this answer
answered Jul 8 '11 at 2:36
Russell McMahon
115k9163289"
"I'll assume that these are power supply capacitors.
Short answer:
45C is tolerable.
Cooler would be better.
Taking steps to minimise temperature will improve lifetime, especially in a continuously on application.
All similarly specified capacitors are not created equal. Brand may matter.
Long! answer:
That's hotter than you'd expect in a simple power supply circuit, but should be tolerable - but see below re operating lifetime that you can expect. "Rule of thumb" is that capacitor life halves for every 10 degrees C rise in temperature. If your capacitors are ~ 45C externally assume that the core is at say 55C. That's (105-55) = 50C lower than rated so lifetime will be about 2^5 = 32 times longer than nominal rating. Most capacitors (especially 105C rated ones) have a 2000 hour or better rating so you could expect a lifetime of about 2000 x 32 = 64000 hours or about 8 years of continuous operation. Even if core temperature was 65C that would give 4 years continuous. If the modem is run 24/7, as it may well be, then capacitor failure in the say 2 to 10 year timescale is not unexpected. What lifetime did you get from the original capacitors? And was the modem operated continuously?
Capacitors are also rated for "ripple current" and exceeding the ripple current rating will increase internal heating and reduce lifetime. This is an additive effect with temperature. eg If two capacitors are operating at 50C then the one with a larger ripple current will have a shorter lifetime. Formulae are available to allow ripple current lifetime derating calculations (not to hand at present, I can provide if useful).
Ripple current ratings can vary widely between capacitor model and manufacturer. Using a known reputable brand of capacitor is recommended in demanding applications as specification sheets for unknown brands are often suspect, often having been copied from those of other manufacturers. [[This claim is based on my having personally tracked down the source of a significant number of data sheets of capacitors and other products when the claims did not seem to match reality. Internet searching on an unusual phrase will often allow the source to be located.]]
Operating your modem without its case is liable to reduce capacitor operating temperature and increase lifetime. Anything else you can sensibly do to reduce ambient temperature will also help. If you measure a 45C cap temperature in a 20C ambient room, if you then operate the modem in a 30C enclosure the cap temperature will probably be 55C or higher.
Fan cooling may make sense. But just replacing the caps when they fail or buying a new modem may be preferable. Heatsinks for capacitors are not unknown but are not common. Anything you can do to sensibly improve airflow will help. eg if it has no case then orientation may not matter much, so orienting it to improve air flow may be possible.
A datasheet or manufacturer's information should tell you
Rated operating temperature.
Lifetime at rated temperature.
Ripple current.
ESR (less commonly)
If they don't tell you the first three, buy another brand. ESR is important but is reasonably well correlated with the other parameters. You can buy capacitors with 3000 hour or 5000 hour or even longer lifetimes at rated temperature, but cost is liable to be higher to much higher. You can buy capacitors with higher than 105C temperature ratings but they are usually much less common and probably expensive.
There are many well known & reputable brands. Panasonic make a wide range of grades, generally seem to "know their stuff" and often are not much dearer than little known or unknown brands. They are certainly not the only brand to consider but are a good starting place.
Distributors like Digikey (DigiKey Electronics - Electronic Components Distributor) stock a vast range of brands and models. Digikey have an excellent parametric search engine that allows you to selectively subset based on many different parameters. Even if you buy elsewhere their product search engine is a useful tool. Also see FindChips: Electronic Components, Distributor Inventories, Datasheets [[No association with Panasonic or Digikey apart from being a satisfied user and customer/ database user.]]
shareimprove this answer
answered Jul 8 '11 at 2:36
Russell McMahon
115k9163289"
thank you oc11 this is super helpful.
in the case of the ACA, are we just talking C1 the big one or also c2? would c3 or c4 potentially be affected?
Anyone else dealt with heat damage before? My guess is this is what happened to my ACA.
To repeat advice already given,
Most likely fault is a dry or poor solder joint. A poor joint may work fine for a while, but repeated hot / cold conditions and current flow will cause it to fail eventually (days, months or even years later). So check for loose connections and poor joints on the board and in the wiring. Prod the individual components and solder joints with a wooden or plastic stick. Take some good pictures and we can have a look too.
Second is to do some simple voltage checks as in the build guide. Compare the 'good' channel to the distorted one, report anything not the same back here.
Caps would be a way down the list of possible faults - though not impossible for one to fail early perhaps. I'm sure that there are plenty of ACAs out there with a lot more hot hours than yours, and no reports of cooked capacitors as far as we know.
Alan