Audio Research ref 110 hot resistors

I seem to be going through a phase of trails & tribulations with the ref 110's :tears:. Managed to purchased a matched octet of of Winged C 6550s after trying out other tubes that did not work for me.

Now, I just discovered a bank of resistors near the front right portion of the amp are very hot. 100 deg C or thereabouts. How can this be ? Both my ref 110s are like this.

Anyone care to share or check their ref 110 ?

Regards,
Joe Ling

Hi Joe, You sure it is not Fahrenheit you are reading?

That's some serious heat if it is at celcius.. no knowledge of amp circuit work for me.. hope other members can help.

No lah, 100 deg F only 38 deg C. Touch still ok. The only reason I noticed was because of burning smell when I opened the protective cage recently. Did some checking with my infra red thermometer (used for heading RC model engine head temp.) & discovered the alarming temperature.

Already emailed my dealer to ask him to check with factory how to do.

Regards,
Joe Ling

joeling wrote:No lah, 100 deg F only 38 deg C. Touch still ok. The only reason I noticed was because of burning smell when I opened the protective cage recently. Did some checking with my infra red thermometer (used for heading RC model engine head temp.) & discovered the alarming temperature.

Already emailed my dealer to ask him to check with factory how to do.

Regards,
Joe Ling

What was the reason of this investigation ? The burning smell from your seat or was it due to a below par sound quality?

cheers

The tubes in my pair of ref 110's were worn out after 2000hrs of use. I had sets of KT120's purchased earlier thinking that they will improve the sound once I swap out the old tubes. Turned out that I did not care of the sound of KT120's. Bought Svetlana 6550's to replace not realising I should be getting winged 'C' if I want to stick with ARC factory original tubes.

When I inserted the Svetlanas, noticed burning smell. Switched off immediately & changed back to KT120's. Checked temp everywhere in the unit & found the ones in the pic were 100 Deg C.

Switched back to the worn tubes same temp. Swap the Svetlana's into the other ref 110 also same problem. Switched to KT120's in also same temp etc.

Purchased the winged 'C' ones & inserted into the other ref 110 also same thing. So, wondering if it is normal that these resistors are so hot.

Sound with the winged 'C' are as per expectation again. But worry such high temp of the resistors surely not good for the life span of the passive component.

What do you think ?

Add a fan ? or dump it for a ref 150 that I may not like & waste money again.

Regards,
Joe Ling

Wow you surely spent on a lot of tubes after this incident huh.

From the picture and your description of the problem it looks like the 100degC is normal.

Furthermore if there was really a problem, the resistors would not retain their colour - they will turn slight brownish and the PCB area directly below the resistors will also be discoloured - affected by the heat.

If I were you, I'd send the amp to a competent technician, and swap out those resistors to a higher power rating which may only cost less than 20 ringgit in total (minus his labour charges of course).

The blue colour of the resistor (in your picture) looks like a normal metal film 1W 1% tolerance type and is only about 50 cents. So changing them to a 3W metal film should reduce the heat significantly. Any higher power resistors could have problems related to space in the PCB which may not fit.

cheers.

Factory says it's normal. This is good news right ?

joeling wrote:Factory says it's normal. This is good news right ?

If my own built amps are like that I won't sleep well man.

On the contrary since you upgrade amps more frequently than I upgrade my underwear I think you may just leave it alone then.

cheers

No wonder i heard audio research amp not as lasting or degrade in sound quality much faster than other makes. Hmmm, wonder how true it is.
Ya indeed, i find it disturbing too to see the resistors run at 80 to 90% of it capability all the time.

Wikin wrote:

joeling wrote:Factory says it's normal. This is good news right ?

If my own built amps are like that I won't sleep well man.

On the contrary since you upgrade amps more frequently than I upgrade my underwear I think you may just leave it alone then.

cheers

Don't be like that. Not that long ago I was very a DIY guy too. DIY Amp, DIY pre, DIY speakers (Mitsubishi Diatone) & heavy modded DAC...

Regards,
Joe Ling

Ah those DIY days. good memories yeah.

Yes, I was a younger person then. Just married & moved out from my parent's place & on our own...

kakibook wrote:Ah those DIY days. good memories yeah.

Hi joe, is everything fine so far on ur audio research? Or like wikin said u already change to another higher grade of the audio research?

Everything back to normal after I change to correct branded power tubes & replace blown 1ohm resistors. Temp is like that loh.

Now settle back to listening to music & hunting for vinyl. Got any source for mandarin LP's ?


Regards,
Joe Ling

I see, blown resistor wasnt due to over heat ya?
Sorry, i never buy any lp before, i just play around with those pass down fr dad. But u may able to find some better quality chinese lp fr advertisment made on taiwan hifi magazine. I can check fr the www address for u if u r interested.