Jolida JD1501BRC fuse and Power issues.. Help Pls..

SatMumbai

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Hi,

I have recently bought this amp from Oceanic Sound, Pune. The SQ of the amp is very good for the price but I am having some technical challenges with the amplifier.

When the amp is brought to ON from Standby (using Remote) or the front panel switch, the fuse blows, some times. The slow start mode just starts and the amplifier blinks once and that's it. When I replaced the fuse, it lasts few more starts and then the fuse goes off again.

Based on the advice from Oceanic Sound Pune (from where I bought the amplifier), I changed the fuse from 3.15Amps to 4Amps but the problem persists. Now the new suggestion that has come in is to move onto 5 Amps rated fuse. This is not any precision special fuse but procured for 10 Rupees from the local Hardware store. The problem is still there even with the upgrade.

Also, I tested for loudness this evening with an FM, and when the amp was put on to 12' O Clock position (half the rated volume) there was a big noise from the right speaker and sound was gone completely from the right speaker. We reduced the volume immediately and turned off the amplifier. While turning ON the fuse went off again. Luckily after replacing the fuse, both channels are working alright though I do not have the courage to pump up the volume now.

I immediately spoke to Oceanic Sound and was asked to bring the amplifier to them. Mahendraji (from Oceanic Sound) is quite helpful in this matter and I will be taking the amplifier there in next couple of days. I am currently assuming that my particular unit is defective partially and I will exchange it for another unit.

I seek advice from the people who have similar experiences with this or any other amplifier and let me know the possible reasons and solutions.
 
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Sorry to hear about it.

I don't have much experience with tube amps, but I have owned a few and one of them is lying useless now (despite being in warranty) for a similar reason.

In my case, there is no fuse to blow, the amp starts and works as it should, except that the right channel will work sometimes, sometimes it won't. First time it happened I doubted the connection. I checked the connection thoroughly and found that the problem indeed was the amp and not the connections. Reading your description, I find a relevance here (even if it may not really be related).

The problem perhaps started when I "tested" the amp by pushing the volume high. Cause, I can't think of anything else that might have caused the issue as I don't really have a power problem (surges/cuts etc.). However, I can't really be sure if that indeed was the problem or these problems are related in anyway.

I'll be watching how you problem gets fixed. All the best!
 
To my little knowledge , I suspect it is the fault of the tubes in both cases. Replacing the tubes will solve the problem.. If it is an Power/Integrated tube amplifier it will be an costly affair, in case of preamp it will be less.
 
I'll be watching how you problem gets fixed. All the best!

Mine is Valve only on the pre-amp side (tube buffer) but solid state else where.

Hopefully it is nothing major design issue otherwise the new amp might have the same problem.

I will keep us posted once I visit Pune.
 
sat,

kindly visit Pune and get the piece changed. This seems to be a case of a bad piece.

what srini says could also make sense.. maybe the dealer can check with different tubes and play it at higher than normal listening levels for some time..

During cold start ( or even from standby .. when the startup relay activates.. if used.. ).. the tubes may instantly draw power for their startup and probably a faulty tube may be drawing more power than required and normalising at normal listening levels. the problem may be recurring at higher levels as again more current is demanded by the speaker and i suppose this would place more load on the pre-amp section.

On the net the recommend the JJ tubes ( i dont know much about them )..

But i hope you get this fixed asap and continue to enjoy your lovely setup..

wish you luck..

mpw
 
Hi satmumbai

I have never encountered such a problem with any amp. It clearly appears to be a faulty piece.
 
hi satmumbai

the easiest way to check if the tubes are at fault is to switch the left and right channels. if you then hear distortion in the left channel at higher volumes, you'll know it's the tube causing the problem.

i'm not sure what tubes the jolida uses, but as srinisundar mentioned, preamp tubes are pretty inexpensive. check out tubeman.com for prices.
 
Thank you very much. Oceanic sound is pretty nice to deal with. I have even requested them to keep an unit reserved for me, in case there is a problem with my specific unit.

I will run the tests at the shop exclusively with higher volumes and fuse related start ups for a while to replicate on the other units and will pick up the unit which is not faulty.

Luckily the sound of the amplifier is pretty nice so I am very happy on that front :)
 
5A fuse is good for a load of 1200 watts at 220 wall voltage. What is your amplifier power consumption at max? I dont think it will be more than 400~500 watts. A 3A fuse (with 50% overload factor) should be enough. You can also try a Slow Blow type fuse.

The type of problem described- intermittent sound on / off could be several things. Does it always happen at higher output level? Does your amp has an speaker protection device? Maybe that is kicking in.

I will rule out tube problem. The small signal tubes typically draw 1mA and that too after 5 ~10 seconds of power on. The heater current is typically 300mA. Because the currents are so low I doubt if the tubes are the reason for blown fuses.

Hybrid amplifiers have slightly complicated power supply. One section demands high voltage low current. The other wants low voltages and high current. Ideally both the sections should have independent and isolated PSU's.

In any case the best option will be to exchange this amp.
 
5A fuse is good for a load of 1200 watts at 220 wall voltage. What is your amplifier power consumption at max? I dont think it will be more than 400~500 watts. A 3A fuse (with 50% overload factor) should be enough. You can also try a Slow Blow type fuse.

The type of problem described- intermittent sound on / off could be several things. Does it always happen at higher output level? Does your amp has an speaker protection device? Maybe that is kicking in.
The manual says 450 Watts maximum.
.:JoLida: manufacturers of quality audio equipment
For some reason they say it needs a fastblo as per the above link (same in the manual)

I have not tried to repeat this problem with my speakers as I do not want to end up damaging my speakers (I am not even sure if this is possible but I do not want to attempt it at home). I asked Oceanic Sound and they say that there is speaker protection available. This is the first time I have seen Speaker protection kicking in, if that is the case!
 
I am just speculating:

High volume...sudden noise...no sound. This could be some fault at output stage. At high level DC is making an appearance at waveform crossover and triggering the speaker protection.

Maybe the experts can better comment on this. Best to change the amp if possible.

And yes the fuse could be fastblow type as there is power on delay incorporated.
 
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I never experienced the fuseblo and extensively i read in the net before venturing into the tubes.

Below is also from an tube amplifier manual

Plenty of tube amplifier manual states If a fuse blows, replace and check output tube bias. If there is a large change, then an output tube is probably damaged. If the bias has not changed then the cause of the fuse blowing may be due to other problems, such as poor system grounding, unstable preamp, shorted speaker, etc.

Output tubes will need to be replaced periodically. When a degradation in sound occurs, the fuse blows repeatedly, or the tubes will not hold their bias anymore it is time for new output tubes
 
I never experienced the fuseblo and extensively i read in the net before venturing into the tubes.

Below is also from an tube amplifier manual
Thanks for the information.

I am more concerned the fuse blow is not repeating and the amp lasts few start ups till the next time the fuse blows. And when the amp is ON then it sings absolutely well. Only tried till half volume once.
I will see what Mahnedraji (who is also co-founder of Cadence) has to say on this when I take it to him this Tursday. I already told him that I want a new piece but I am more concerned if this is a design issue which spans across the entire crop or it is a pure one off defective unit which is more comprehensible.
 
I am just speculating:

High volume...sudden noise...no sound. This could be some fault at output stage. At high level DC is making an appearance at waveform crossover and triggering the speaker protection.
Thanks Aks. That is what I am suspecting. Let me see if I can reproduce this at his shop on Thursday with Cadence speakers
 
Quick Update:

I visited the Oceanic Sound, Pune yesterday and Mahendraji is very nice and accommodating.

Unfortunately I could not reproduce either of the problems at his shop though after turning the Amplifier ON & OFF ten times. Also, we cranked up the volume and after a point of loudness it was unbearable but the speaker protection circuit did not kick-in. Pretty spooky. I guess my speakers are much inefficient than the speakers we tested in the shop.

Despite of this, Mahendraji offered me another amplifier as replacement (may be to compensate my driving from Mumbai to Pune and give me some piece of mind)
Also, they have changed the fuses on all the amplifiers in their stock to better quality and higher rating. I currently have a different piece of JD1501BRC with 5Amp fuse which is working fine at home as well (No challenges what so ever) since this morning.
I highly recommend Oceanic Sound!

BTW, I made some pictures of the amplifier inside (to have a feel of the inside)

Inside of Jolida JD1501BRC
 
A beautiful, well-constructed speaker with class-leading soundstage, imaging and bass that is fast, deep, and precise.
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