With JM on this one, and it's not necessarily the case that the chip amp will even offer up performance comparable to the circuitry you have removed.
Makes more sense to start from scratch...
Makes more sense to start from scratch...
Of those listed here, I would go for the Luxman. You state yourself, you have only limited experience in DIY. Why not start with something inexpensive and more simple to make work? Should it fail, it didn't cost you much.
True, the "old" amplifiers had to take into account that the class AB driver circuits did not allow going very close to the rail voltages. Today, in particular with class D, the rails can be used much better. But, I have just finished a power supply based on a Technics SU-V500 transformer. 4 new ELNA 9000uF capacitors and I have 2x38V at a very reasonable price.
The advantage of a (higher) voltage that may not be sustained long time at full loading - I have good headroom. I use this power supply with my TDA8954 amplifier and it just sounds fine.
As long as the maximum supply voltage of the amplifier chip is not exceeded, we get good head-room for little money.
The Luxman power supply will probably output 2x40-42Vdc. Good and cheap amplifiers can be found for such voltage.
An IRS2092 based class D amplifier can handle almost any dual rail supply. And, they are not expensive.
For the physical outline of the Luxman, only you know if you like it.
NB: I often buy defect amplifiers where it is not worth paying for a repair. This way I pay very little and the transformer is seldom defect.
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I thougt thread starter was talking about analog chip amplifiers. Isn't that what chip amp section mean? Otherwise there is class d amp section.
Me too, did not think this was a discussion of class D retrofit, if that is the intent then this is the wrong forum and I can move it.
Sorry, "looking for an amplifier to fit a given supply voltage" may have class AB and Class D as suggestions. I will stop the class D suggestions.
I have done exactly what you suggest. Only the power transformers and case was used. The issue with many vintage amps is that they are low current/high voltage which makes using them for a chipamp problematic.
I converted a Technics power amp that used separate transformers for the plus & minus rails. Voltage was a bit higher than specced for the LM3875 so the amp was best for 16Ω speakers.
dave
I converted a Technics power amp that used separate transformers for the plus & minus rails. Voltage was a bit higher than specced for the LM3875 so the amp was best for 16Ω speakers.
dave
Times a thousand on the suggestion of only using these chassis/transformers if you already own them AND using the subsequent amplifier for 16 ohm speakers. Which is all well and good as long as you're the one building everything and know what you're doing (mostly)
Buying a vintage amp to tear it apart, unless it's $5 (or Euros) from a garage sale is a fools errand. So much easier to implement just about any other solution.
Buying a vintage amp to tear it apart, unless it's $5 (or Euros) from a garage sale is a fools errand. So much easier to implement just about any other solution.
Lots of $5 amps around… even ones that work fine. I have lots of broken ones if one wants to come by and pick one up.
dave
dave
Thank you
I see there are many inconveniences doing such a project.
One of the reasons is that I was thinking also that with transformer from old amp we can make a more powerful chip amp or class D amp
I see there are many inconveniences doing such a project.
One of the reasons is that I was thinking also that with transformer from old amp we can make a more powerful chip amp or class D amp
Due to the fact that class D is the most efficient I will continue the discussion at Class D sub forum
If you're going Class D, you're left with just the chassis. The power supply will be useless as it won't be able to provide enough power. OTOH, it should be trivial to fit a small Class D amp with a switching power supply in any old amp chassis.
I know this isn't the cheapest route, but it is certainly worth considering the offerings of ModuShop when it comes to chassis. You can get their products from them directly or through the DIY Audio Store. They ship from Italy.
Now, I do get that buying a chassis is going to be about 100x more expensive than fishing an old amp out of a junk pile, but it'll provide 100x lower frustration level.
Tom
I know this isn't the cheapest route, but it is certainly worth considering the offerings of ModuShop when it comes to chassis. You can get their products from them directly or through the DIY Audio Store. They ship from Italy.
Now, I do get that buying a chassis is going to be about 100x more expensive than fishing an old amp out of a junk pile, but it'll provide 100x lower frustration level.
Tom
Of course few DIYers need to account for the cost of stripping down the organ donor to the requisite level of readiness for new parts, and the cosmetic work of making something presentable, and perhaps their significant others appreciate the peace and quiet if that work is remote enough; but having re-purposed more than a few commercial chassis in my time- and being fortunate enough to not have to pinch every penny - I'd vote for a well proven kit and all new dedicated enclosure for any serious project.
A perfect example is the current ACA kit - I just put finishing touches on a pair for Dave to be used in bridged mode to drive mid-tweeter in a pair of 2-ways. The HiFi2000 chassis were a dream to work with compared to my build a few years ago of mini-aleph that was fabricated by hand from raw aluminum sheet, L-angle and purchased heat sinks. I must have put 20 hrs into the chassis alone - complete build time on the pair of ACA, including stuffing the boards was less than that . I also used one of the Galaxy enclosures for a Hypex UcD180 build - but had to drill/machine the rear panel by hand. Never buy /work with steel chassis if you can help it 😉
A perfect example is the current ACA kit - I just put finishing touches on a pair for Dave to be used in bridged mode to drive mid-tweeter in a pair of 2-ways. The HiFi2000 chassis were a dream to work with compared to my build a few years ago of mini-aleph that was fabricated by hand from raw aluminum sheet, L-angle and purchased heat sinks. I must have put 20 hrs into the chassis alone - complete build time on the pair of ACA, including stuffing the boards was less than that . I also used one of the Galaxy enclosures for a Hypex UcD180 build - but had to drill/machine the rear panel by hand. Never buy /work with steel chassis if you can help it 😉
Unless, of course, one's entertainment is wrapped up in the actual fabrication process as its own set of puzzles. And sliced up hands. If the end goal is having a product to use, then DIYaudio is a terrible endeavor, so we're all in it for the journey aspect, in some fashion or another. 🙂
Sliced up finger tips, indeed - I already get enough slivers from working with plywood and veneer, thank you very much. 😉
An old case can be made "nice" again. But, yes, it's time consuming and somewhat frustrating at times.
if the old amp is nice looking, it is fairly straight forward.
1. make a small PCB for the chip amp
2. take all output amplifier components off the main board
3. mount chip amp onto heatsink using any of the output transistor locations
4. connect i/p , output , gnd and power to the chip amp board.
you may be able to get some of these connections to line up with the chip amp board
Class D requires alot less power from the supply but may need 12V relative to the negative power rail
1. make a small PCB for the chip amp
2. take all output amplifier components off the main board
3. mount chip amp onto heatsink using any of the output transistor locations
4. connect i/p , output , gnd and power to the chip amp board.
you may be able to get some of these connections to line up with the chip amp board
Class D requires alot less power from the supply but may need 12V relative to the negative power rail
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