The results of th LPUHP amps look promising. I am using 4 of them in a bia-amping configuration to run a pair of elsinores. The 15 db version is about the perfect gain for these speakers with the DAC I am using.I will be comparing them to 4 My Ref C amps.
When they were initially turned on the LPUHP amps lacked presence in the treble and sounded muddy with not a lot of detail. Don't be dismayed though because just after a couple hours of burn in all that has changed. I think the LPUHP are going to be contenders for some excellent amps if they are paired with the right speakers. I am going to give them some more time to run in, then will be doing some a&b comparisons with the My Ref C.
When they were initially turned on the LPUHP amps lacked presence in the treble and sounded muddy with not a lot of detail. Don't be dismayed though because just after a couple hours of burn in all that has changed. I think the LPUHP are going to be contenders for some excellent amps if they are paired with the right speakers. I am going to give them some more time to run in, then will be doing some a&b comparisons with the My Ref C.
Thanks Neel, I found the answers I was looking for
Would someone be able to point me to a good chassis to fit both channels, or two chassis would be ok too. What fuse rating should I be using for 120v operation with 50VA transformers? Thanks!
Thanks Neel, I found the answers I was looking for
Would someone be able to point me to a good chassis to fit both channels, or two chassis would be ok too. What fuse rating should I be using for 120v operation with 50VA transformers? Thanks!
Hmm, Your location would be a factor in chassis selection, guessing you are in North America though because of the fact you are using 120v for your transformers. I use par metal enclosures,
Par-Metal
But picking an enclosure is so subjective because of peoples visual considerations. Keep in mind the LPUHP have the heatsinks on the board(which is a bonus for this amp I think) so the enclosure can just basically be a box. Is it more of a size of enclosure that you are looking for a recommendation? Some of my stuff I just go to the local electronics parts store and get an enclosure like a hammond or a made in china box.
For the fuses it is always best to start low then work your way up. 50 Va times 2 = 100Va. 100Va/120V =.8333A. I would start with a 1amp fast blow fuse to start. In my case I am running 4 50va power transformers protected by a 2 amp fuse then have a 1 amp fuse for each of the 2 power transformers for each channel.
Yeah, I am glad the boards have heatsinks already. I am just looking for a standard Hammond enclosure or something. What is a good dimension to fit both the amps in one box with a little room to spare for wiring/cooling and such? Thanks for the advice on the fuse, I was think 1amp myself so thats good to know
Build, Phase One
Phase one of my DSP/DAC > Amp > Speaker build is complete and has had its inaugural 3hr play
Used 2x15Vac 50VA transformers, gain set to 2.1 [~ 4Watt] for powering FH3 speakers fitted with Mark Audio Alpair 7.3 [6 Ohm] .
Pictures:
1... Good enough for me, just ignore the bit of tissue paper
2... LPUHP along side a variation I built early last year... Will be using that to power the helper woofers I'm currently building.
3... Pretty tidy layout for me...
4... Clockwise. Oppo, Pioneer, Variation & LPUHP... Once the 2-way active front end is complete, I'll need to get some kind of insert for where the volume control should be on the two amp enclosures.
Regards,
Paul
Phase one of my DSP/DAC
Used 2x15Vac 50VA transformers, gain set to 2.1 [~ 4Watt] for powering FH3 speakers fitted with Mark Audio Alpair 7.3 [6 Ohm] .
Pictures:
1... Good enough for me, just ignore the bit of tissue paper
2... LPUHP along side a variation I built early last year... Will be using that to power the helper woofers I'm currently building.
3... Pretty tidy layout for me...
4... Clockwise. Oppo, Pioneer, Variation & LPUHP... Once the 2-way active front end is complete, I'll need to get some kind of insert for where the volume control should be on the two amp enclosures.
Regards,
Paul
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That is an absolutely fantastic build!
I wish mine were as nicely cased up
Chassis layout is fantastic, not too big, but plenty of room to breathe. Fully dual mono, AC power wires kept well away, and it's all neat and tidy!
I plan to do something just like this but with balanced inputs and a chassis that probably won't look that nice
Let us know how it sounds once you've got some hours on it!
Cheers,
Owen
I wish mine were as nicely cased up
Chassis layout is fantastic, not too big, but plenty of room to breathe. Fully dual mono, AC power wires kept well away, and it's all neat and tidy!
I plan to do something just like this but with balanced inputs and a chassis that probably won't look that nice
Let us know how it sounds once you've got some hours on it!
Cheers,
Owen
I just want to verify that using this PSU for the LPUHP is ok with the current BOM.
http://www.digikey.com/product-detail/en/VPT36-1390/237-1334-ND/2090072
I've been reading in this thread that 18v secondaries may require higher voltage rated capacitors? Does that apply to the updated LPUHP? Thanks.
http://www.digikey.com/product-detail/en/VPT36-1390/237-1334-ND/2090072
I've been reading in this thread that 18v secondaries may require higher voltage rated capacitors? Does that apply to the updated LPUHP? Thanks.
the caps in BOM are rated at 25 volts. 1.4 * 18 = 25.2. The no load voltage on the transformer may be higher and your line voltage may be a bit higher from time to time so I would say no to a 0-18 0-18 volt transformer. I changed my BOM to use 35 volt caps and also changed the voltage regulator resistor values to give me +/- 22 volts on the rails. I also had to use a different input op amp LME49860. Why did I change things around. The higher rail voltages give a slight improvement to dynamic range. Output is now 13.8 VRMS into 8 ohms or a little over 23 watts.
thanks again Owen
thanks again Owen
Multisync:
Excellent answer to the question, and some excellent info on the "overclocked" LPUHP.
Getting the additional voltage headroom is very beneficial, especially with an 8 ohm load.
I might give that a try myself and see how it works.
Brunk:
As Multisync mentioned, you can use 18V secondaries if you change the caps before the reg, but I really don't suggest it, especially if you haven't bought the transformers yet.
Go with 15V secondaries, and use the 25V caps. You get more capacitance, and put less stress on the regulators. There is absolutely no benefit to 18V secondaries.
Everyone else:
It should be noted (in case it wasn't already obvious) that the above mentioned rail voltage increase done by Multisync can only be done if you swap out the LME49990 for a higher voltage op-amp like the suggested 49870.
If you try this with the stock op-amp, it probably won't survive for very long, and could take the whole amp and speaker with it when it fails.
Cheers,
Owen
Excellent answer to the question, and some excellent info on the "overclocked" LPUHP.
Getting the additional voltage headroom is very beneficial, especially with an 8 ohm load.
I might give that a try myself and see how it works.
Brunk:
As Multisync mentioned, you can use 18V secondaries if you change the caps before the reg, but I really don't suggest it, especially if you haven't bought the transformers yet.
Go with 15V secondaries, and use the 25V caps. You get more capacitance, and put less stress on the regulators. There is absolutely no benefit to 18V secondaries.
Everyone else:
It should be noted (in case it wasn't already obvious) that the above mentioned rail voltage increase done by Multisync can only be done if you swap out the LME49990 for a higher voltage op-amp like the suggested 49870.
If you try this with the stock op-amp, it probably won't survive for very long, and could take the whole amp and speaker with it when it fails.
Cheers,
Owen
They would! I'd probably suggest heatsinks at that rail voltage and with the higher available output power.
As for the name... perhaps a combination of overvolt and overamped.
Overvamped perhaps?
The good news is that the buffers are generally good for higher peak currents than the 250mA rating in the datasheets, so you can actually make use of the higher rails into an 8 ohm load.
Did you happen to measure the -f3 point at the high end? I've had the boards on a scope to check for high frequency oscillations, but I forgot to check where they start rolling off
Cheers,
Owen
my sine generator is only good for 100k and the board was flat to 100k. I was going to use my RF generator but there is something wrong with the grounding on it. The rf generator sometimes sparks when I hook the ground on the generator to the ground of the scope. The generator is around 50 years old or more, an old tube heathkit that someone gave me +40years ago. Normally when I use the rf generator I just place the output lead close to whatever I am testing. The device under test would normally saturate if the connection was direct. (rf tuners)
isn't a vamp someone who is of a loose character?
Urban Dictionary: vamp
I have some heatsinks that I will use. I have to cut them down to size but the table saw is burried in the back of the garage for the winter.
Urban Dictionary: vamp
I have some heatsinks that I will use. I have to cut them down to size but the table saw is burried in the back of the garage for the winter.
I have a question about the LME49610TS. I have soldered a bunch of these with a hot air station at approx. 350c temperature. I have noticed a couple have a copper color on the very first pin. Does this mean I overheated them and burned something? Is there a way to tell without powering up? Here is a picture of one in question. Thanks.
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Looks to have melted the plating off, to the base metal, Cu perhaps.
Suggest to use the fine tipped nozzle and focus on the land area.
Main Section > SRA Soldering Products, Aoyue types 1124-1198,1142
Looks like a little bit of solder wick required for pin 3
Have to be cautious of de-lamination when you see this.
Suggest to use the fine tipped nozzle and focus on the land area.
Main Section > SRA Soldering Products, Aoyue types 1124-1198,1142
Looks like a little bit of solder wick required for pin 3
Have to be cautious of de-lamination when you see this.
Looks to have melted the plating off, to the base metal, Cu perhaps.
Suggest to use the fine tipped nozzle and focus on the land area.
Main Section > SRA Soldering Products, Aoyue types 1124-1198,1142
Looks like a little bit of solder wick required for pin 3
Have to be cautious of de-lamination when you see this.
My hot air station is a 858D, and I used the fine tip nozzle. I think it started to happen when I started heating up the ground plane, ensuring all of the solder was melted underneath and watching the flux come out and flow freely.
Do you think it's ok? Should I use a lower temp than 350c?
If it is working, it must be okay, I guess ?
Depends on solder type, temp and airflow.
In my SMT soldering technique, I hand solder everything, under 10x mag using 15 mil no-clean glow core eutectic solder. Very little pkg stress. I only use the hot air machine to remove comp's or re-flow very small areas.