Proton: High End Or Junk?

[deaf_head]

What did you clean it with......

Unfortunately a cheap ebay solution. Later i tried some decent spray and it removed the heavy feedback that snuck in, but it didnt restore the R channel which i think is damaged via the volume switch itself.
An exhaustive internet search has yielded no replacement. Closest i found was the similar 14 pin but had motor control for about the same price i paid for the amp. The one that is suited is not available.
https://www.aliexpress.com/item/32927709208.html?spm=2114.12057483.detail.3.5181304drFKa1t
I think you might be onto something.. "If I recall, the D540 uses carbon tracks (instead of metal) inside its volume pot. I once tore one of these traces by accident, lost volume on one side iirc, and later restored it using a Caig CircuitWriter silver pen."
Im pretty sure i need to replace or repair the switch. It looks like a real nice job... lol
I am not sure i have the necessary skill but might try to tackle it one day. At this point there is not much to lose as mono sounds like crap.
Thank you for your reply and tips, much appreciated !!

 

[deaf_head]

Does anyone know if plugging in a stand alone pre-amp would bypass the D540 internal pre-amp?
I see a proton pre-amp for sale online and was wondering if this method could eliminate a faulty pre-amp circuit or chip.

 

[avionic]

Does anyone know if plugging in a stand alone pre-amp would bypass the D540 internal pre-amp?

Yes it would by-pass the D540 pre-amp. Any pre-amp would work. Doesn't have to be a Proton.

 

[deaf_head]

Yes it would by-pass the D540 pre-amp. Any pre-amp would work. Doesn't have to be a Proton.

cool thanks !

 

[Splatter Pak]

BTW, the Proton amps, at least the AA-1150 is NOT dual-mono. Some of the circuitry looks dual-mono, but the power supplies are not truly dual-mono. If you've ever looked under the hood, you know that the two power transformers do not look alike. That is because one is for normal operation, while the other is for DPD operation.

 

[karljansen]

BTW, the Proton amps, at least the AA-1150 is NOT dual-mono. Some of the circuitry looks dual-mono, but the power supplies are not truly dual-mono. If you've ever looked under the hood, you know that the two power transformers do not look alike. That is because one is for normal operation, while the other is for DPD operation.

I can't imagine that the D1200 is anything but dual mono (see photo of mine below). The hifi engine page refers to it as "dual mono," but I notice the AA-1150 is not referred to as dual mono on its corresponding page:

https://www.hifiengine.com/manual_library/proton/d-1200.shtml
https://www.hifiengine.com/manual_library/proton/aa-1150.shtml

 

[egellings]

I'd call it high end consumer, but not audiophile grade.

 

[onanysunday]

The circuits I've heard in the D540, D940, AM300 are very good as-is with their supplied components. With well considered recaps and other upgrades to passives, they can be very high-end sounding and respond better to component upgrades than most other gear I've worked on hoping for such results. I have a D540 integrated that completely blows me away with its dynamics and realism (for its relatively low power rating) and sounds better than most any pre/power separate combo I've heard with the same wattage rating as the D540.

Does HiFi mean anything besides brand recognition or the price we pay for something? There's no real agreement on it, so it's unquantifiable. There are specs to fall back on, but even the best specs (in themselves) do not necessarily guarantee pure audio bliss. In a word, I'd say the endless pursuit of absolute 'precision' in playback equipment can only take us so far before it reaches a point of dimishing returns. While there are still some smaller improvements to be had, I do believe we've reached that zenith long ago. At some point, the human ear is only as good as a human ear can be.

With their 6-7dB of headroom on DPD models, after a bit of re-work and hearing them, I'd put them squarely in audiophile territory. As a brand (to me) they represent real potential in stock form, and one of the best price/performance values in this hobby. That's not to say they're built to last forever, without at least some occasional maintenance, just that they can sound really good when working properly.

 

[deaf_head]

I'd put them squarely in audiophile territory. As a brand (to me) they represent real potential in stock form, and one of the best price/performance values in this hobby. That's not to say they're built to last forever, without at least some occasional maintenance, just that they can sound really good when working properly.

Id agree. Back in the day when i bought my first D540 new in 1986, i tested it on the shelf besides other high end gear and the D540 was only bettered by the top of the line $1000+ NAD amp they had.
I was hoping something like this https://www.ebay.com.au/itm/234055214849 would help me attain both channels as currently i have lost the R unless in mono.

 

[onanysunday]

Id agree. Back in the day when i bought my first D540 new in 1986, i tested it on the shelf besides other high end gear and the D540 was only bettered by the top of the line $1000+ NAD amp they had.
I was hoping something like this https://www.ebay.com.au/itm/234055214849 would help me attain both channels as currently i have lost the R unless in mono.

That has the Schotz tuner like my D940, but no second transformer for DPD. If going Proton, I'd be looking for models with two transformers- either dual mono, or primary with a secondary. Then again, I've never heard any of their single transformer models- I've been spoiled on hearing only DPD models, hence my strong bias towards them.

 

[deaf_head]

That has the Schotz tuner like my D940, but no second transformer for DPD. If going Proton, I'd be looking for models with two transformers- either dual mono, or primary with a secondary. Then again, I've never heard any of their single transformer models- I've been spoiled on hearing only DPD models, hence my strong bias towards them.

If using the above amp as pre-amp for D540, the dual transformer will still work on the D540?
Im just trying to work around a lost R channel on my D540. I suspect the onboard pre-amp but ive had issues with the volume switch recently.
In the very least i could use the above preamp by itself with both channels but one transformer if it wont remedy my D540 problems.
The proton amps are getting hard to find now and most people have mega jacked up prices if they know what they are holding.
This one above seems reasonably priced but considering i only paid $90 for this D540 about a year ago, it is still expensive

 

[hornbostel]

I currently run a Proton D940 driving a pair of Smaller Advents (4 ohm) in my work office. I pull down FM most of the time. The Schotz tuner is world class. A Schiit Modi 3 provides digital. I’ve got some nice amps (Schiit Yamaha etc). The Proton is right there with them. The Proton will drive anything. And sound great. I am looking for another 940 or 540 so that I can run them monoblock. Three little guys can crank out 600 watts dynamic as monoblocks!

 

[onanysunday]

If using the above amp as pre-amp for D540, the dual transformer will still work on the D540?
Im just trying to work around a lost R channel on my D540. I suspect the onboard pre-amp but ive had issues with the volume switch recently.
In the very least i could use the above preamp by itself with both channels but one transformer if it wont remedy my D540 problems.
The proton amps are getting hard to find now and most people have mega jacked up prices if they know what they are holding.
This one above seems reasonably priced but considering i only paid $90 for this D540 about a year ago, it is still expensive

Remove the top cover and try spraying all your pots and switches with plastic safe contact cleaner while working them back and forth. Once it dries, follow it with green DeOxit FaderLude for the dials which use carbon traces and red D100L the buttons. That may restore a lost channel, and it's also part of general maintenance required to keep Protons going. With the cover off and power off, inspect all fuses and components to see if anything looks off; like bulging capacitors or burnt sections on the main board. It could very likely just be dirty controls.

 

[deaf_head]

Remove the top cover and try spraying all your pots and switches with plastic safe contact cleaner while working them back and forth. Once it dries, follow it with green DeOxit FaderLude for the dials which use carbon traces and red D100L the buttons. That may restore a lost channel, and it's also part of general maintenance required to keep Protons going. With the cover off and power off, inspect all fuses and components to see if anything looks off; like bulging capacitors or burnt sections on the main board. It could very likely just be dirty controls.

hmm yeah i got into trouble while cleaning it. Some dirt fell into the gaping hole in the volume switch which looks designed to engulf all dust that enters the case.
That is when the trouble started. First by using cheap crap ebay spray which i think might have damaged the carbon traces. I have since cleaned the switches with decent spray which removed the monster feedback that crept in. But since that day of cleaning i have intermittently lost R channel in stereo but not mono, although it seems the mono is heading in the same direction after noting a R drop out recently. I couple of flexes on the volume switch made it come back, just like it used to in stereo before becoming a permanent loss.
Capacitors all look ok but i suspect cracked solder somewhere on the mainboard as well as volume switch which could be ok now but has left or exposed a trail of issues.

 

[onanysunday]

You can still squirt a fair amount of Deoxit D100L red in the hole while working it back and forth pretty good, remove the bottom panel and check solder joints on the volume pot to see if any are cracked.

 

[deaf_head]

You can still squirt a fair amount of Deoxit D100L red in the hole while working it back and forth pretty good, remove the bottom panel and check solder joints on the volume pot to see if any are cracked.

Yeah ive already tried the spray and it seemed to fix some feedback and i think the switch is as clean as possible but, i still have zero output for R channel.
I bought the 930 listed above today so i will wait for delivery and try the D540 using the 930 as pre-amp. If that fails to remedy the R channel i will simply use the 930 as main and retire the 540.

 

[deaf_head]

You can still squirt a fair amount of Deoxit D100L red in the hole while working it back and forth pretty good, remove the bottom panel and check solder joints on the volume pot to see if any are cracked.

Heya OAS do you have any experience with these pre-amps on Protons? Probably a silly question but i see behavior that is stumping this newbie.
I got my 930 today and set it up by itself with a cheap DVD input and two speakers out. The FM is good and havent tried the AM but its reported as weak by the seller. no issue.
Both channels lively on FM. I throw in a music cd and i have one missing channel. palm slap to forehead! (ive been chasing a lost channel for two years on my D540 and is the reason why i bought this 930 lol)
So i figure pre out from 930 to main in on D540 should give both channels if indeed the DVD player has a borked channel. So i swapped out speaker cables and plugged in pre-out 930 to main in 540.
Both channels work but i cant control volume or other buttons on the 540. Im not sure if this is normal but i thought i would have control of the main.
Now i cant tell if the 540 amp is active but i guess it has to be.
I read somewhere about shorted cables fitted to the main in for 930 when using pre-out for other amp. What this does i have no idea and ask is this necessary?
Im looking around and i have no other input device for stereo output other than the 930. pretty sad.

 

[onanysunday]

Well, I haven't got the whole picture yet, but we can say a few things at least. Namely, the power section of the D540 has stereo output, and that the 930 (by itself) is capable of stereo sound at least in FM. Also, it's normal to have only control of the 930 when you use it as preamp to the D540. When using the D540 as a power amp only, it should become unresponsive to its volume control. The 930 will control all sound adjustments when it's used as a preamp. When using the 930 as a standalone unit and were not getting stereo sound out of a CD, were you hooked up to the 'Tape' or 'Video' inputs on back of the 930? Try the other set of inputs with your DVD Player and see if you can get stereo sound out of the 930 from a CD by itself when not hooked up to the D540.

It doesn't really make sense you would suddenly hear both channels of a CD coming out of the D540 if you are still using the same set of bad RCA inputs (either Tape or Video) on the 930 that didn't allow you to hear stereo CD sound coming out of the 930 directly in the first place when used as a standalone unit. When used as a power amp only, then of course both sets of speaker wires should then be plugged into the D540.

 

[deaf_head]

it's normal to have only control of the 930 when you use it as preamp to the D540.

ok, that was my main concern.

I waited for a decent song on FM and gave it some stick to check if DPD on the 540 was working to confirm the amp was acting as main.
Holy snappers its loud and punchy.

 

[just dave]

I've only heard positive things about Protons.