Welcome! Need support, you got it. Or share your ideas and experiences.
hi i was pointed in this direction by zarniwoop who has been very kind in helping out with my problem. before i go further i must caution you that i am a total idiot in electronics - the only reason i took on the ella was to challenge myself, wean myself off 'hi end' kit and equally 'hi end' dealers and learn about this craft and boy do i have a lot to learn :)so here goes. i completed the kit and was getting weird figures ont he meter which didnt tally with the numbers in the manual. checked wiring and found that chassis ground was not secure and vol pot ground had a bad joint - fixed this and was getting the right numbers save for the last 2 stages.
i rechecked the wiring and as it was suggested that there might be a cold solder joint with the 10ohm/4 watt resistors to ground, i checked this and yes there was and fixed it. the latest readings i got are:
A5 - D5 - 50vdc
A2-A7/B2-B7: 6.19 vac (it was 6.27 last night)
C2-C7/D2-D7: 6.22 vac
pins 7 n 8 on main pcb: 6.22 vac (6.26 last night)
B+: 425 vdc (390 vdc last night)this is the strange part:
when i put in the 6550s and checked the bias rca, instead of getting .4vdc i was getting 250 mvdc. i stopped here and did not carry on with the other tubes.question: is the power ground and signal ground connected in this amp? i remember being told that it shouldnt - but i may have heard wrong.
is the centre pin of the bias rca connected to ground?
finally what gives? would appreciate any help
Follow Ups:
I've never built one of these kits (yet) but the safety ground and the signal ground(the one off of the main PCB) and a chassis ground should all connect together with individual wires at the negative side of the last capacitor on the power supply PCB. This is called a star ground. If they are not recommending that you use this configuration in the instructions then shame on them. This is the best way to ground any audio circuit SS or tube. It almost gaurantees that you will not get a ground loop induced hum coming out of your speakers. Also remember to twist the leads on the primary of the power transformer together when routing them for wiring and the same goes for the secondary leads as well as the primary and secondary leads for the output transformers. I hope this helps.
Take a look at how the wiring looks in this amp:http://www.idealinnovations.ca/gallery/s30internal.jpg
These amps do essentially have a star grounding scheme. Thats why the RCA jack ground must be returned to the star ground instead of being arbitrarily grounded to some point on the chassis. Often the chassis safety ground is NOT connected to the star ground point if this induces hum because of its interaction with the power transformer. But that sacrifices the safety effects, of course. So a solution is to connect the safety ground to another point on the chassis far from the star ground point.Long story short.. no ground loop problems or coupled 60hz hum and a safety ground in place. No worries.
I've heard of people on the BottleHead forum talking about isolating the RCA jacks from the chassis and running the nagative pin of the jack straight to signal ground and then also taking a .1uF ceramic disk cap and tying it from the negative RCA jack pin to the chassis. This might work well for the Ella and Joplin. But this is just speculation. I wonder if the problem with the hum on the Ella is due to the use of an aluminum chassis instead of a steel one. If they are steel chassis and steel covers on the transformers there shouldn't be any magnetic coupling of the transformers. If there is no magnetic coupling going on then there should be no reason for star grounding not to work everytime. Not just sometimes.G
To clarify, there is no problem with hum on the ella. The small amount of hum reaching the speakers could be reduced even further with more power supply filtering. I don't even have a filter choke and the hum is only audible when putting your ear up to the speaker. Both the chassis and the tranformer covers are steel.I didn't mean to imply there was a problem. It was more just information for what you can do in general IF you encountered something like this.
(yay me...I finally registered after a year and half or something)
I see. I guess I'm just a little miffed at being informed that if I want a choke in the power supply of my Ella(if I order one) then I will have to modify the PCB board and shoehorn a choke in. On the DIYCable site it says that the Ella comes with a choke supply designed into it, not that you will have to modify the kit to use one. Then I misunderstand about the severity of the hum problem that is being discussed. I thought that I had wasted all of the time drooling over the Joplin and the Ella only to find out that they are not such good deals after all. I'm releived to find out that this is not the case. One other trick that I have seen done is to twist together the chassis ground and the safety ground wires and then solder a 10 ohm resistor bypassed by a .1uF cap on to the ends of the twisted wires and attach the resistor and the cap to the star ground point. This is supposed to work well at breaking up ground loops. Thanks for setting me straight Zarniwoop.
hey! Your readings are looking good now. The 6.3VAC heater is okay to be +/- 10% or so. This will change a little as your mains voltage varies from time to time (normal).250mV for the bias just means that it is biased on the low side now (25mA). The next step is where you adjust the bias pots to make them all read the same number. 0.45V (45mA) is suggested for el34s, 6550s could go higher, but I won't get into that now. It should play music at 25mA bias though.
I have the power safety ground connected to the chassis near the IEC connector. The signal ground should be connected only to the main PCB, IIRC. (wire goes from RCA jack ground to the GND on the PCB). So while they are not directly connected, they do both connect to the chassis at different points. This arrangement keeps hum from being picked up on the input. If you get lots of hum, you could try leaving the saftely ground unconnected.
I think you can safely try it out now with all the tubes inserted. Let us know how it goes or of any other problems that come up.
-zarni
hi zarni, thanks for the reply. i will check it out tonight - question: the silver bias rca - are the centre pins connected to ground as well? i remember testing them earlier and they were not - only the barrels to chassis ground butnot the centre pin .
thanks
mikey
No, not grounded - those are the bias test points. They should be connected to pin 8 (cathode) of the output tube sockets. This is where you read the voltage dropped across the 10ohm resistor. 0.45V, for example.The outside barrels don't need to connect to anything. But be sure to have your voltmeter negative probe in contact with a ground when measuring the bias voltage at these test points. (the black speaker terminal, for example).
hi, so i have a problem then. i connected the 10r/4w resistors as instructed - ie, one lead across pins 1 & 8 and the other lead connected to another resistor in the next socket. between pins 1 & 8, a wire to the bias test points. where the 2 leads of the resistors connect, a wire to the psb star ground. i get continuity between the bias test point and ground - whether power switch or star ground. the barrel/tab is grounded too - but i expected that as the chassis is grounded. does this add up?
cheers
mikey
I may be confusing you more because I don't have an instruction manual in front of me. Follow that if in doubt."one lead across pins 1 & 8 and the other lead connected to another resistor in the next socket. between pins 1 & 8, a wire to the bias test points. where the 2 leads of the resistors connect, a wire to the psb star ground"
above is all correct.
"i get continuity between the bias test point and ground - whether power switch or star ground."
that is not correct. you should have 10ohms between the test point and ground. ie pins 1 & 8 only connect to ground through that resistor. I'm not sure how, but you must have either pin 1, 8 or the bias rca center pin accidently shorted to ground.
Check resistance between each bias test point and ground with the amp off. Should be 10ohms.
Hi, congratulations, I hope to be successful too.
I also need help with the ELLA beacuse I do not have the instructions.
Can somebody provide me the instructions for the KIT?
I have seen several schemes, so I think I can understand most of it, like 22k potentiometer for bias from the 50 Volts to C connections on PCB but some aspects are unclear.
I know it is a tough job to scan the manual, but it will be very helpful if somebody can provide me the instructions.
Thanks
hi antonio, didnt you get the instructions with your kit?
Sorry, what a shame it was in the Box !
hey alberto, well you got that sorted out now so its time to study the manual and get cracking. i had fun doing mine although there were times when things got a bit hairy as you can see from my posts but i had more fun than hairy situations ;) - in fact had so much fun that im kinda having withdrawal symptons from not having solder fumes to inhale.
cheers
Ended up and working with a very nice sound.
I have only some doubts:
The actual bias resistance measured is 10 to 13 ohms depending on the pot. Do I need to adjust the bias corrspondingly, that means 0.4V for 10 ohm and some 0.52V for the 13 ohm to have the same current?
The power transfor wiring colours are brown=0, blue=110V and red=120V,my ella is wired for 220V but actual net Voltage is 234V is it better if I rewire?
Some times the soft start relé is not activating, some times yes, is this linked to the power transformer wiring and the actual voltage on relé?
Output volume is quite high, would it be better if I change to 100k potentiometer for better regulation?
cheers
Alberto
hi alberto, im afraid i cant answer your queries - im very much a newbie and still learning the ropes - the best persons to advise you would be brian cherry or zarniwoop or any of the othe forummers who have a better technical grasp of things. may i suggest that you re-post your message addressing either of these 2 gentlemen.
cheers
mikey
nt
hi zarni - thanks for the reply. i just took apart the bias resistor and bias test point network on one tube socket - no shorts between the pins or the rca centre pin but when put back together (with croc clips), the rca bias centre pin is continuous with ground. is it possible that the bias resistor could be bad? - havent had much experience with wirewounds or 10 ohm value but other resistors in higher values do not have continuity between each lead. this one does - which means that the the rca centre pin is being hooked up with ground through the wire from the ground cluster of the pcb that joins the resistor leads between 2 sockets. oh man im bushed. sorry for troubling you zarni - im going to bed now - its past 3 am here.
thanks again
mikey
Strange.. maybe it is a bad resistor. Have you checked all four of them? It sounds like you are focusing on one of the 4 sockets, but you don't say if the other three are checking out. One resistor may be bad, but all four... not likely. That way we can be sure its the resistor and not the wiring. You should take the suspect resistor out of the circuit and measure it with an ohmeter. Usually a resistor will open-circuit if it is damaged, but its possible that it shorted, or that it was not good to begin with.No trouble at all, btw. I'm sure you will get this sorted out and have a perfectly working amplifier (and great sounding too, these are nice). gnight
hi zarni, thanks for the encouragement - i was having the problem that i addressed in my earlier post with all 4 sockets - i undid the bias network on all 4 sockets and i can confirm that there is no shorting between the pins and the jacks. i procured fresh wirewound resistors of almost similar value - 10r/5w and surprise surprise - there is continuity as well. since they were going cheap - i got more of the same value from different vendors and same thing -continuity. a new lesson for me today - resistors of low values have contintuity. as the resistors that came with the kit are somewhat gnarled - im gonna pop in the new resistors and give it a go tomorrow and i will post what happens.
cheers
mikey
hi zarni, sorry for the shout but yes it works!!. and it works beautifully man:)thank you zarni and thanks to brian and G for the tips and the encouragement - im going to be up late - obviously - im looking forward to the burn in process - and, me being me, im already thinking of upgrades to it - but im only thinking - im not going to do this now - i will enjoy these stock - the only thing that is not stock about it is the kimber tcss wiring throughout. you are right about the sound of the amp - its amazing right now - i can only imagine that it would be absolutely spectacular after burn in.
thanks very much again
mikey :)
Glad to hear its up and running. It will likely "break-in" a little bit from my experience. Of course there are lots of possible upgrades/mods/tweaks, but I think you are taking the right approach and getting used to it stock first. I'll share some of my mods in a future post, but they certainly are only optional.
Enjoy,
-zarni
hi zarni, thanks - and looking forward to your tips on modding the amp.
cheers
mikey
forgot to add that brian has been helping out too - this guy is patience personified. thank you brian.
This post is made possible by the generous support of people like you and our sponsors: