Finally after a Looooong hiatus I'm getting around to building my first amp.
LM1875 chip amp. 2 sites I came across. Neurochrome,( really professional layout & offers populated boards that will be handy as a reference tool) & Elliott Sound Products project 72.
Project 72 is what I decided on as I have a lot of the components on hand and it appears simple to construct.
I'm ordering the chips tomorrow.
Here WERE some pics of what I have scounged and collected so far which for some bizzare reason I cannot seem to upload. Oh well care factor less than zero.
LM1875 chip amp. 2 sites I came across. Neurochrome,( really professional layout & offers populated boards that will be handy as a reference tool) & Elliott Sound Products project 72.
Project 72 is what I decided on as I have a lot of the components on hand and it appears simple to construct.
I'm ordering the chips tomorrow.
Here WERE some pics of what I have scounged and collected so far which for some bizzare reason I cannot seem to upload. Oh well care factor less than zero.
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pictures user error corrected
Here are the pretty pictures I failed to upload before .Woops the admin keeps saying invalid link.I will keep trying to post pics however long it takes. Like the native american indians who's raindance
never failed to bring rain sometimes dancing for 20 years or more I will not stop trying to upload the pictures until they upload.
No matter if it takes hours days weeks or years.
Here are the pretty pictures I failed to upload before .Woops the admin keeps saying invalid link.I will keep trying to post pics however long it takes. Like the native american indians who's raindance
never failed to bring rain sometimes dancing for 20 years or more I will not stop trying to upload the pictures until they upload.
No matter if it takes hours days weeks or years.
You should able to attach the images by using the Go Advanced option below and clicking on the paperclip icon ("attachments").
I don't actually offer any amp with the LM1875 but have plenty with the LM3886. If you're starting from scratch with your LM1875 circuit, I suggest reading through my Taming the LM3886 article series. While many of the details apply specifically to the LM3886, most of the information applies to any chip amp.
Best luck with your build.
Tom
I don't actually offer any amp with the LM1875 but have plenty with the LM3886. If you're starting from scratch with your LM1875 circuit, I suggest reading through my Taming the LM3886 article series. While many of the details apply specifically to the LM3886, most of the information applies to any chip amp.
Best luck with your build.
Tom
Cheers
Yeah I know Tom, you don't offer a LM1875 amp. And thanks for the upload advice but this is a "security label is missing" issue. My game plan is to go active with mini DSP and use one of your amps as a reference + bass duties. The LM1875 will be on tweeter duties I have some gear on hand to build 2. 2 18-0-18v 160VA transfomers 4 100uF 400v Jantzen poly cross caps each is slightly smaller than my fist. 4 Elna NOS made in Japan 85c 8000uF 75V. 2, 2uF poly's bypassed with Mundorf gold / silver oil .33uF. Heat sinks are off a 150 wrms plate amp kindly donated by Adelaide speakers. Rod Elliot has been around a while & the project 72 looks like the best beginner project for me from a trusted no nonsense source.
After that if I don't cook myself or the amp/s then its time to get serious & build one of yours.
Cheers Mark
Yeah I know Tom, you don't offer a LM1875 amp. And thanks for the upload advice but this is a "security label is missing" issue. My game plan is to go active with mini DSP and use one of your amps as a reference + bass duties. The LM1875 will be on tweeter duties I have some gear on hand to build 2. 2 18-0-18v 160VA transfomers 4 100uF 400v Jantzen poly cross caps each is slightly smaller than my fist. 4 Elna NOS made in Japan 85c 8000uF 75V. 2, 2uF poly's bypassed with Mundorf gold / silver oil .33uF. Heat sinks are off a 150 wrms plate amp kindly donated by Adelaide speakers. Rod Elliot has been around a while & the project 72 looks like the best beginner project for me from a trusted no nonsense source.
After that if I don't cook myself or the amp/s then its time to get serious & build one of yours.
Cheers Mark
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Weird. You might want to start a thread in the Forum Problems section.
Sounds like a good project. I'll have boards for you when you're ready. Enjoy.
Tom
Yeah real weird. Been uploading pics here since 2012. Last 5 years with the same service provider and 3 with the same method & same phone. ADMIN!
I think I would like a populated board me thinks as a sq & assembly reference from you. But first things first.
Ordering the chips tomorrow.
Cheers
I think I would like a populated board me thinks as a sq & assembly reference from you. But first things first.
Ordering the chips tomorrow.
Cheers
Use my amps on all channels.
You'll most likely notice the largest sound quality improvement if you use any of my Modulus amps on the tweeters and mids. I'm sure there will be improvements in the bass as well as the Modulus amps have very high damping factor, but in terms of imaging and detail the mids and highs are probably where you'll get the biggest improvement. That'd be my guess based on my knowledge of the amps.
As far as which of my amps to choose: Depends. How much power do you need? The Modulus-86 provides 40/65 W into 8/4 Ω. Modulus-286 (mono) provides 50/100 W. I'll soon have a Modulus-686 that I expect to provide about 150/300-ish W. The MOD86 and MOD286 sound the same. The '286 has slightly lower noise floor which is nice if your speakers are super efficient.
I use 4xMOD86 powered by a Power-86 and an Antek AS-3222 (2x22 VAC, 300 VA) transformer to power my LXmini speakers. The crossover is a MiniDSP 4x10HD. That works great.
Tom
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Your transformer & capacitance values are a bit oversized for LM1875. Should work though. You need some resistors, coupler caps, fuseholder fuse or CB, switch, speaker and input terminals,
I've built two channels on bare board. Used 2200 uf caps, single supply out of ST datasheet so I don't blow up speaker with DC from a bad solder joint. Plenty of those so far; it works now when I probe it but not by itself. Waiting for fall rains and maybe a magnifying ring light to debug more.
Personally I use 1/4 watt listening level on 8 ohm 101 db/1W speakers. 70 watt would get 55 db peaks but that is not necessary for casual listening. 25 Watts should be fine. I used 24 vac average transformer, 2.5 Amps for two channels.
I've built two channels on bare board. Used 2200 uf caps, single supply out of ST datasheet so I don't blow up speaker with DC from a bad solder joint. Plenty of those so far; it works now when I probe it but not by itself. Waiting for fall rains and maybe a magnifying ring light to debug more.
Personally I use 1/4 watt listening level on 8 ohm 101 db/1W speakers. 70 watt would get 55 db peaks but that is not necessary for casual listening. 25 Watts should be fine. I used 24 vac average transformer, 2.5 Amps for two channels.
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Cheers Tom
My power needs are modest. (Near field monitoring) the speakers I will be running have an efficency ranging from 91dB @2.83v for the bass/mid with 4 Ohms nominal. 95 for the ribbon tweeter. The other less efficient option is my older Peerless nomex 5"s which have around 88.5 dB efficiency with backing magnets @ 8 Ohms nominal with Seas dome tweeters with around 92 dB @ 6 Ohms nominal. The latter have custom HDF cabs. The former marine ply that have not been finished yet. I think I will use the Peerless/ Seas setup as that active will reap the greater benifit from this implementation. The ribbon set up is a very unusual and rare combination designed by Adelaide Speakers. It runs the woofer full range with a simple XO on the tweeter and is one of the finest 2 ways I've ever heard. Rare as not many combinations can get away with such a simple design of XO. If it aint broke. Don't fix it. Can't say that about the Peerless/Seas HDF combo.
My power needs are modest. (Near field monitoring) the speakers I will be running have an efficency ranging from 91dB @2.83v for the bass/mid with 4 Ohms nominal. 95 for the ribbon tweeter. The other less efficient option is my older Peerless nomex 5"s which have around 88.5 dB efficiency with backing magnets @ 8 Ohms nominal with Seas dome tweeters with around 92 dB @ 6 Ohms nominal. The latter have custom HDF cabs. The former marine ply that have not been finished yet. I think I will use the Peerless/ Seas setup as that active will reap the greater benifit from this implementation. The ribbon set up is a very unusual and rare combination designed by Adelaide Speakers. It runs the woofer full range with a simple XO on the tweeter and is one of the finest 2 ways I've ever heard. Rare as not many combinations can get away with such a simple design of XO. If it aint broke. Don't fix it. Can't say that about the Peerless/Seas HDF combo.
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@indianajo Yup I agree but its what I have on hand & I will compare with local gain clones & see if going boutiqe on the bits makes any difference. If not it will at least look cool under the hood. Ha!
Oh you forgot to mention cases but I have some stuff on hand to make those from 2.5 mm alu sheet. A few bits & pieces to go but getting close now.
Oh you forgot to mention cases but I have some stuff on hand to make those from 2.5 mm alu sheet. A few bits & pieces to go but getting close now.
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I've posted a few details on my Facebook page: Neurochrome - Home | Facebook
Think BPA200 but with enough output current to drive a 4 Ω load well on ±35 V rails. So 2x3xLM3886 in a bridge/parallel amp with a composite error correction loop. I hope to have the design ready in time for US Thanksgiving (late November) to hit the Christmas build season.
I'll post some progress updates on the prototyping on Facebook, open up for pre-orders here and via my Newsletter once it's ready to go and I have boards underway from the manufacturer.
Tom
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A Modulus-86 - or Modulus-286 (stereo) if you don't mind the SMD soldering - would be perfect then.
Tom
tough act to follow
Plugged in the HDF peerless 5inch 2 ways today. On simple music they are sublime. Very revealing but obviously a slight lack of energy in the mid bass compared to the 8 inch 3 ways. I might have found them wanting on a day I was slightly depressed. Sorry no photos because although everything seemed sorted yesterday. Not today. Over it Bye
Plugged in the HDF peerless 5inch 2 ways today. On simple music they are sublime. Very revealing but obviously a slight lack of energy in the mid bass compared to the 8 inch 3 ways. I might have found them wanting on a day I was slightly depressed. Sorry no photos because although everything seemed sorted yesterday. Not today. Over it Bye
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