Power up noise
I get weird pops and bangs on one channel when I turn on. Starts after about ten seconds and finishes five minutes later, presumably when the amp has warmed up.
Swopped over the 4x EL34s and still the same, though the volume pot seems to have some effect, though not cures it. Then when warmed up all is fine.
Any ideas guys ?
I get weird pops and bangs on one channel when I turn on. Starts after about ten seconds and finishes five minutes later, presumably when the amp has warmed up.
Swopped over the 4x EL34s and still the same, though the volume pot seems to have some effect, though not cures it. Then when warmed up all is fine.
Any ideas guys ?
It could be one of the front end valves, try swapping them over with the other channel and see if the noises move over. If they don't then you probably have a problem with connections, try cleaning the valve pins. You could also try powering up without the front end valves fitted. For example, if the fault is with the left channel, try powering up with V1 removed (V4 on the right channel). No noises? then fault around the input circuitry but if noises remain try removing the splitter V2 (V3 on right channel).
In this way you should be able to zero in on the stage giving you the problem. It sounds like you have a valve problem to me.
In this way you should be able to zero in on the stage giving you the problem. It sounds like you have a valve problem to me.
Thanks Hi Q, yes swapped over the two end front valves and all the bursts and pops vanished, though the other channel now has a hum.
Before I buy new valves, I believe there is an opportunity of replacing them with something different. Back in these pages someone did a mod, can't remember the details
Before I buy new valves, I believe there is an opportunity of replacing them with something different. Back in these pages someone did a mod, can't remember the details
Power Supply Delay Board
Hi, This is my first post here. I own a MC-13S and I was thinking to install a Power supply delay board which I found on ebay.
Power Supply Delay Board Dynaco ST70 EL34 6550 KT88 6L6 6V6 EL84 Tube Amplifier | eBay
Can anybody tell me how?
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Yaqin MC-13S (Mundorf SUPREME & Takman) Mod, NAD D1050 Dac, B&W 684 Speaker, Yamaha 775 Receiver, Samsung 55" F8000, Xbox One, WireWorld Oasis 6 Interconnect, Van den Hul Clearwater Speaker Cable.
Hi, This is my first post here. I own a MC-13S and I was thinking to install a Power supply delay board which I found on ebay.
Power Supply Delay Board Dynaco ST70 EL34 6550 KT88 6L6 6V6 EL84 Tube Amplifier | eBay
Can anybody tell me how?
__________________________
Yaqin MC-13S (Mundorf SUPREME & Takman) Mod, NAD D1050 Dac, B&W 684 Speaker, Yamaha 775 Receiver, Samsung 55" F8000, Xbox One, WireWorld Oasis 6 Interconnect, Van den Hul Clearwater Speaker Cable.
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Valve shoot out
Hi I have a failing EL34, so time to replace the set. Has anyone compared them to KT77s or 6CA7s ?
KT77/EL34/GENALEX/GEC/GOLD LION R.U
www.thetubestore.com - JJ KT77 Audio Tubes
www.thetubestore.com - Electro-Harmonix 6CA7EH Audio Tubes
Hi I have a failing EL34, so time to replace the set. Has anyone compared them to KT77s or 6CA7s ?
KT77/EL34/GENALEX/GEC/GOLD LION R.U
www.thetubestore.com - JJ KT77 Audio Tubes
www.thetubestore.com - Electro-Harmonix 6CA7EH Audio Tubes
Lessee - I've run TungSol EL34s, JJ KT77s, Mesa EL34 (rebranded someone-I just don't know who) and Valve Arts 350Bs. Any impression of any of the above is a little jumbled in my mind's ear right now as I've been down for 3 months doing a complete front-end rebuild. Tube Depot and some others might have some impressions of each tube's character for you though.
I should also note I'd been running 6922/6DJ8s almost from the start - which I like quote a bit better than the 6N1. More rolling possibilities.
I used the MC-10T (the version with 12AT7s) and it did not have enough power to drive Magnepan 1.6QRs. Maggies are current hungry.
I did, however, use a 250WPC solid-state amp for the bottom panel and the Yaqin to drive the tweeter. With a simple RC filter to roll the bass off, the tube amplifier had enough power to drive the higher frequencies.
After this mod I was expecting a noticeable drop in output volume, but hardly if any difference. Is that right ?
Also the amp has gradually become bass light, coincidence perhaps. Could this be my valves getting old ? Got no others to compare with sadly.
Removing the negative feedback should give an increase in volume if anything. I have a 100b which is switchable between Triode or Ultra Linear modes, I also notice slightly less punchy Bass in Triode mode so keep it set to U/L. You can only fit the 12xxx series valves if you first re-wire the heaters to the four pre-amp valves. The resent 6N1's have 6.3V heaters on pins 4 & 5 and pin 9 is grounded as it is an internal screen. If you fit a 12AT7 then pin 9 has to be isolated and connected to one of the heater wires. The remaining heater wire has to connect to both Pins 4 & 5.
Thanks Les,
My problems have been solved.
1) Lack of bass was cured by replacing all power valves with Gold Lion KT77s. Really superb, apart from restoring the low end they are an amazing listen and worth the praise they receive. Propels this amp into a different league.
2) Glitches and bangs during warm up were dirty pins on the four 6N1s cured by wiping them with WD40
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A trip back in time to reawaken this thread.
I've recently acquired an MC-10T, an excellent amplifier. Dead chuffed to have EL34's back in my life.
I have been wondering how the amp would look without the transformer covers on. Odd maybe but has anyone come across a picture of such a thing?
Cheers.
I've recently acquired an MC-10T, an excellent amplifier. Dead chuffed to have EL34's back in my life.
I have been wondering how the amp would look without the transformer covers on. Odd maybe but has anyone come across a picture of such a thing?
Cheers.
