I have an old dinosaur of an amplifier here that I use for my party system. I swapped the woofers over for a couple of 4R drivers and it's been getting quite warm lately.
It's an Inkel ARM1200
Dual mono
63V 10.000uF smoothing caps and SanKen 2SC2774//SSA1170
Been really reliable but this is the first time I've had it driving 4R loads.
It's got output metres on the front rated to 200W into an 8R load but I have no idea what it might be rated into a lower impedance speaker.
Driving big old fashioned Alpine 12"car subs to handle some party bass that are supposed to be rated 300 watts.
Is expecting 300 watts realistic?
It's an Inkel ARM1200
Dual mono
63V 10.000uF smoothing caps and SanKen 2SC2774//SSA1170
Been really reliable but this is the first time I've had it driving 4R loads.
It's got output metres on the front rated to 200W into an 8R load but I have no idea what it might be rated into a lower impedance speaker.
Driving big old fashioned Alpine 12"car subs to handle some party bass that are supposed to be rated 300 watts.
Is expecting 300 watts realistic?
It looks like you've asked about your dinosaur's capabilities before. Inkel power amp ARM 1200
Each channel appears to have a single pair of regular epitaxial MT200 output transistors which should be good for about 100W/8R, 150W/4R.? However, a single pair of output transistors isn't a good idea for low impedance loads, despite being the big Sankens. 2-4 pairs and heavier supplies makes for a more reliable amplifier at 2-4 ohm loads.
The bigger question is, do you really need the maximum output capacity that the speakers can handle or just a comfortable listening level? There's no requirement to match the power ratings of devices unless its a retail decision to optimise the cost for cheapest power/dollar ratio. With existing gear, you could probably power typical car audio speakers as loud as the net load impedances and domestic authorities permit.
As for testing power, I doubt you could get meaningful results other than by comparing meter readings with those of hefty dummy loads. The meters fitted are likely just representative of power to a fixed, nominal load resistance. A real speaker has reactance and is quite frequency dependent, so the meters are mostly ornamental.
Each channel appears to have a single pair of regular epitaxial MT200 output transistors which should be good for about 100W/8R, 150W/4R.? However, a single pair of output transistors isn't a good idea for low impedance loads, despite being the big Sankens. 2-4 pairs and heavier supplies makes for a more reliable amplifier at 2-4 ohm loads.
The bigger question is, do you really need the maximum output capacity that the speakers can handle or just a comfortable listening level? There's no requirement to match the power ratings of devices unless its a retail decision to optimise the cost for cheapest power/dollar ratio. With existing gear, you could probably power typical car audio speakers as loud as the net load impedances and domestic authorities permit.
As for testing power, I doubt you could get meaningful results other than by comparing meter readings with those of hefty dummy loads. The meters fitted are likely just representative of power to a fixed, nominal load resistance. A real speaker has reactance and is quite frequency dependent, so the meters are mostly ornamental.
I never got an answer so thought it better to ask again Ian.
You are probably right about the loading as the sticker on the back does say 8 to 16R speakers but I was assuming that was when using 2 pairs in parallel.
I sort of wanted my subs to be able to keep up with the tops so the bass needs a bit more power. I do try and keep the volume down to the legal limit but our neigbours all come to my parties when we have them
If it's only 100 watts that will work if I use a different amp for the tops, I have a spare Rotel with 60 * 6 outputs after all
You are probably right about the loading as the sticker on the back does say 8 to 16R speakers but I was assuming that was when using 2 pairs in parallel.
I sort of wanted my subs to be able to keep up with the tops so the bass needs a bit more power. I do try and keep the volume down to the legal limit but our neigbours all come to my parties when we have them
If it's only 100 watts that will work if I use a different amp for the tops, I have a spare Rotel with 60 * 6 outputs after all
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I think the sensitivity of your subwoofers might be the issue. Car power amplifiers can be big or small depending on the speaker driver design, frequency range and quality. If you can find specifications for what you have there, you may then be able to determine what you need to keep up with the "tops".
It can probably drive 4 ohm loads.
Depends on the power levels.
Most people listen to music at somewhat moderate levels
So the amplifier would be ok with 4R loads at low levels.
If you start pushing them hard then the amp is going to get hot.
Sensitivity of subs or car subs can be on the low side.
So to fill a medium or large room. It can take a lot of power.
If the amp is only rated for 16R or 8R loads.
Then a 4R load is going to start heating up those heatsinks.
Most sub amps have a crossover, so if your just powering the subs directly.
Alot of extra heat is going into the subs voicecoils as well.
Amplifiers best friend is forced air cooling from a fan
Depends on the power levels.
Most people listen to music at somewhat moderate levels
So the amplifier would be ok with 4R loads at low levels.
If you start pushing them hard then the amp is going to get hot.
Sensitivity of subs or car subs can be on the low side.
So to fill a medium or large room. It can take a lot of power.
If the amp is only rated for 16R or 8R loads.
Then a 4R load is going to start heating up those heatsinks.
Most sub amps have a crossover, so if your just powering the subs directly.
Alot of extra heat is going into the subs voicecoils as well.
Amplifiers best friend is forced air cooling from a fan
Don´t assume "moderate-comfortable" levels,from the first post t´s clearly stated:
Amp is clearly rated "8-16 ohm" , speakers are power hungry and their impedance is suspect, usage is full power and beyond, for *hours* .... what could go wrong?
EDIT: As of power out capability, beyond guessing based on transistor case and such, a more accurate approch is:
* Measure rail voltage
* multiply by 0.8 to get full load voltage
* substract 4V for power transistor end emitter/ballast resistor drop
* this is your realistic peak output voltage on a speaker load, driven HARD.
* multiply by .707 to get realistic RMS voltage.
* calculate RMS/Continuous power.
To boost, driving power hungry inefficient
Even worse, rated 4 ohm can easily mean dropping to 2 ohm at some frequencies, car woofers cheat to get maximum SPL in competitions or comparisons.
Amp is clearly rated "8-16 ohm" , speakers are power hungry and their impedance is suspect, usage is full power and beyond, for *hours* .... what could go wrong?
EDIT: As of power out capability, beyond guessing based on transistor case and such, a more accurate approch is:
* Measure rail voltage
* multiply by 0.8 to get full load voltage
* substract 4V for power transistor end emitter/ballast resistor drop
* this is your realistic peak output voltage on a speaker load, driven HARD.
* multiply by .707 to get realistic RMS voltage.
* calculate RMS/Continuous power.
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I have an contact who does audio repair locally as a hobby.
I'll drop it off with him tomorrow and get him to check it out, will cost me a 6-pack of good beer. Then I'll know for sure.
With the smoothing caps being 63V I'd guess rail voltage would be around 50V?
So maybe 80Watts is closer to the mark?
I'm not an amplifier feller, speakers are my interest really. The amp predates Inkels takeover of Sherwoods brand and while Inkel did make a lot of Sherwood amplifiers I've never seen a Sherwood that looks like this monster
I'll drop it off with him tomorrow and get him to check it out, will cost me a 6-pack of good beer. Then I'll know for sure.
With the smoothing caps being 63V I'd guess rail voltage would be around 50V?
So maybe 80Watts is closer to the mark?
I'm not an amplifier feller, speakers are my interest really. The amp predates Inkels takeover of Sherwoods brand and while Inkel did make a lot of Sherwood amplifiers I've never seen a Sherwood that looks like this monster
If you can’t hold your hand on the heat sink, it’s too hot and you need either more air flow or lower dissipation.
Amplifiers using +/-50 volt supplies need one PREMiUM output pair for ever 8 ohm load just for survival - assuming that you can hold your hand on the heat sink. 4 ohms requires 2 pairs (and that’s if your using the best ones available like Sanken). If you don’t have two don’t use 4 ohms.
Amplifiers using +/-50 volt supplies need one PREMiUM output pair for ever 8 ohm load just for survival - assuming that you can hold your hand on the heat sink. 4 ohms requires 2 pairs (and that’s if your using the best ones available like Sanken). If you don’t have two don’t use 4 ohms.
Moondog,don´t you have multimeter on hand?
You´ve already opened it, just measure voltage across any of the big power caps.
The calculations I suggested re conservative, in a high quality amp, meaning oversized transformers and big cap banks it may be, say, up to 20% more.
But still worried about those speakers being too low an impedance.
If he has the needed power load resistors, ask him to measure power at clipping into 8 nd 4 ohmloads, just in case.
You´ve already opened it, just measure voltage across any of the big power caps.
The calculations I suggested re conservative, in a high quality amp, meaning oversized transformers and big cap banks it may be, say, up to 20% more.
But still worried about those speakers being too low an impedance.
If he has the needed power load resistors, ask him to measure power at clipping into 8 nd 4 ohmloads, just in case.
If you blow MT200 case output transistors they are end of life & might be out of stock or expensive. US distributors drop end of life products as soon as it is announced.
Best hit the used market & get a PA rated 2 ohm rated amp. Peavey CS800 or PV-8c, Crown cs1000, xli800 xli1200 microtech models, Yamahas can be reliable. Power rating up to twice the rating of the speakers prevents clipping & tweeter meltdown. Bands are selling off class AB amps, transformers are too heavy to carry with class D available. I got a CS800s with switcher supply for $140 last spring.
Longevity tip, open the top and Clean the heat sink & fan with alcohol, they are usually filthy. Dirt conducts no heat.
Best hit the used market & get a PA rated 2 ohm rated amp. Peavey CS800 or PV-8c, Crown cs1000, xli800 xli1200 microtech models, Yamahas can be reliable. Power rating up to twice the rating of the speakers prevents clipping & tweeter meltdown. Bands are selling off class AB amps, transformers are too heavy to carry with class D available. I got a CS800s with switcher supply for $140 last spring.
Longevity tip, open the top and Clean the heat sink & fan with alcohol, they are usually filthy. Dirt conducts no heat.
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Subs are not the same although both are old car subs
One is this old school driver in a ~200l drum
Cheapskate dumpster diving speaker
I'll see if I can get to the boards base to measure voltage but I'm headed to this feller this PM get him to checkout this and an older Rotel which has a dicky rotary encoder.
Going by the physical size of the old E&I transformers I'd guess somewhere around 300VA tho
As for SPL these are used outside and the yard is of reasonable size and usually between 30 and 50 people here
One is this old school driver in a ~200l drum
Cheapskate dumpster diving speaker
I'll see if I can get to the boards base to measure voltage but I'm headed to this feller this PM get him to checkout this and an older Rotel which has a dicky rotary encoder.
Going by the physical size of the old E&I transformers I'd guess somewhere around 300VA tho
As for SPL these are used outside and the yard is of reasonable size and usually between 30 and 50 people here
Running in series? Well I could run a length of wire from one boxes return terminal to the other boxes positive and run a separate wire back the amp I guess and hook something else up the other channel, fidelity isn't all that important for dance music
Just took the shield off and measured; all 4 caps measure 54V and all near enough to the same measurement
Cool.
Applying the Math I suggested above you´d get conservative 96W RMS into 8 ohm and maybe up to 110-120W RMS if, as I suspect, your dual power transformers are well rated.
The beefy cap banks I already see.
If at all possible build/wire 2 4 ohm cabinets (as you have now) in series *per side* for dual 8 ohm loads.
Over true 200W RMS (total) driving 4 woofers will be wall shaking and perfect for your parties.
In theory your amp might produce 150W per channel into 4 ohm, but you not only risk overheating but also prematurely triggering protection circuits, which give buzzy/chattering distortion , a horrible sound, not worth it.
Better 100 good loud clean 100W per channel, than buzzy trublesome 150.
Applying the Math I suggested above you´d get conservative 96W RMS into 8 ohm and maybe up to 110-120W RMS if, as I suspect, your dual power transformers are well rated.
The beefy cap banks I already see.
If at all possible build/wire 2 4 ohm cabinets (as you have now) in series *per side* for dual 8 ohm loads.
Over true 200W RMS (total) driving 4 woofers will be wall shaking and perfect for your parties.
In theory your amp might produce 150W per channel into 4 ohm, but you not only risk overheating but also prematurely triggering protection circuits, which give buzzy/chattering distortion , a horrible sound, not worth it.
Better 100 good loud clean 100W per channel, than buzzy trublesome 150.
If better smoothing caps were available I might consider new ones as these are over 30 YO but then again it might be putting lipstick on a pig unless everything was done over and getting a new amp might be cheaper.
"Audio Reflex had a full range of equipment at the budget to mid-price range, all OEM-made by Japanese, Korean and other Asian manufacturers, and it varied from ordinary, to excellent quality for the money.
Much of their equipment seems to have been sold in Canada (as you’d expect), and in Australia, where AGS Electronics Australia, who later changed their name to Audio Reflex Australia, distributed them. In my 1980 Directory, I found they sold an equaliser, dynamic expansion/compression processor, amplifiers, receivers, speakers, cassette deck, headphones, car cassette/radio, and car equaliser/amp, so they certainly sold everything! Because they were such good value, and had a three year warranty, their equipment sold very well in Australia, but it was probably available for less than a decade with the Audio Reflex name" Audio Reflex MR-140 turntable - anyone know anything about this unit? - Vinyl and Turntables - StereoNET International
Трансляционные усилители мощности INKEL: купить в интернет магазине INKEL в Украине - 4Club
inkel md 1200 - YouTube
Much of their equipment seems to have been sold in Canada (as you’d expect), and in Australia, where AGS Electronics Australia, who later changed their name to Audio Reflex Australia, distributed them. In my 1980 Directory, I found they sold an equaliser, dynamic expansion/compression processor, amplifiers, receivers, speakers, cassette deck, headphones, car cassette/radio, and car equaliser/amp, so they certainly sold everything! Because they were such good value, and had a three year warranty, their equipment sold very well in Australia, but it was probably available for less than a decade with the Audio Reflex name" Audio Reflex MR-140 turntable - anyone know anything about this unit? - Vinyl and Turntables - StereoNET International
Трансляционные усилители мощности INKEL: купить в интернет магазине INKEL в Украине - 4Club
inkel md 1200 - YouTube
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Previous post.
Strange photos without front and back views. Heatsink of regular size. Rectifier diodes are small without cooling. Transformers for 150-200 W (difficult to estimate the size). The current can be estimated from the fuse markings.The power is approximately 2x100 W RMS.
Strange photos without front and back views. Heatsink of regular size. Rectifier diodes are small without cooling. Transformers for 150-200 W (difficult to estimate the size). The current can be estimated from the fuse markings.The power is approximately 2x100 W RMS.
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