Hi all i need some advice,
I am rebuilding my year-old hand wired, tube regulated (wish it wasn't, it causes big thump when they strike) botched up Aikido amplifier.
It has served me trouble free a long time but i still get nervous switching it on... so time to build it nice and relax a bit to the music.
I'm a student on a tight budget and have been considering power iron for the amp.
Is hammond a good choice?
the 2xx series power transformers are about half price of the 3xx series, i can work around the primary voltage issues no probs but i read the 2xx series are worse built and leak more flux?
I am also looking into dual power supplies per channel, this will eat all my cash up.. i can just about afford it but is it worth it?
I already have an old 350-0-350 @ circa 150mA transformer that works if i run both channels from it.
Many thanks!
P.S. im planning on ordering Aikido pcb's + sockets + attenuator kit from glass-ware, is the attenuator a worthwhile purchase?
I am rebuilding my year-old hand wired, tube regulated (wish it wasn't, it causes big thump when they strike) botched up Aikido amplifier.
It has served me trouble free a long time but i still get nervous switching it on... so time to build it nice and relax a bit to the music.
I'm a student on a tight budget and have been considering power iron for the amp.
Is hammond a good choice?
the 2xx series power transformers are about half price of the 3xx series, i can work around the primary voltage issues no probs but i read the 2xx series are worse built and leak more flux?
I am also looking into dual power supplies per channel, this will eat all my cash up.. i can just about afford it but is it worth it?
I already have an old 350-0-350 @ circa 150mA transformer that works if i run both channels from it.
Many thanks!
P.S. im planning on ordering Aikido pcb's + sockets + attenuator kit from glass-ware, is the attenuator a worthwhile purchase?
As an enthusiast I can sympathise with you wanting to use separate power supplies for everything, I like to too.
You don't have to use separate power transformers though for two reasons:
1) You are powering a pre-amp which is probably not pushing the transformer hard and is probably drawing a fairly steady current and 2) You have regulators.
Simply use a separate regulator for each section if you want a completely independent supply.
or
Group up stages within your amp that you feel will probably be OK on the same supply and use separate RC legs coming off a single regulator.
BTW, what's the attenuator for?
You don't have to use separate power transformers though for two reasons:
1) You are powering a pre-amp which is probably not pushing the transformer hard and is probably drawing a fairly steady current and 2) You have regulators.
Simply use a separate regulator for each section if you want a completely independent supply.
or
Group up stages within your amp that you feel will probably be OK on the same supply and use separate RC legs coming off a single regulator.
BTW, what's the attenuator for?
Thanks for replies guys!
Ill go with both your advice and go single supply, i know 2 supplies is overkill but when your building somthing overkill is an attractive option
.
I will consider regulating each channel independantly, probably with some 0A2's/0B2's controlling a series pass tube like a 6V6 maybe? but ill see how it goes with a C-L supply first as i have 3 x 20H +1 x 8H chokes and loads of 1000uf@385v caps to experiment with.
The attenuator is going to be for the input to the Aikido amplifier to allow adjustment of signal into the circuit. I could use a dual POT but i used this before and it crackles and doesnt track each channel evenly (2-3dB's difference!) very annoying.
If i do go regulated then relays for anti thump seem attractive, probably best as a safety precaution anyway....
Craig
Ill go with both your advice and go single supply, i know 2 supplies is overkill but when your building somthing overkill is an attractive option
. I will consider regulating each channel independantly, probably with some 0A2's/0B2's controlling a series pass tube like a 6V6 maybe? but ill see how it goes with a C-L supply first as i have 3 x 20H +1 x 8H chokes and loads of 1000uf@385v caps to experiment with.
The attenuator is going to be for the input to the Aikido amplifier to allow adjustment of signal into the circuit. I could use a dual POT but i used this before and it crackles and doesnt track each channel evenly (2-3dB's difference!) very annoying.
If i do go regulated then relays for anti thump seem attractive, probably best as a safety precaution anyway....
Craig
Split bobbins are those where the primary and secondary are either would on completely separate bobbins or one that is segmented (split). The primary and secondary do not overlay. This greatly reduces capacitive coupling between primary and secondary, a plus for reducing line noise coupled to the secondary and rectifier hash coupled back to the primary (and then on to other circuits).
Broskie is not a stupid guy. He sent me Aikido boards and parts knowing that, even though I don't need a preamp with gain, I'd build it anyway out of curiosity, measure it, play with the circuit a bit, and then save him a pile of work by troubleshooting the early builds here.
Broskie is not a stupid guy.
He sent me Aikido boards and parts knowing that, even though I don't need a preamp with gain, I'd build it anyway out of curiosity, measure it, play with the circuit a bit, and then save him a pile of work by troubleshooting the early builds here.
I wouldn't recommend the use of a Hammond 2XX series transformer on 50Hz as they already run fairly warm under load on 60Hz, 50Hz operation will make this much worse. The 3XX is really a much better transformer, runs quieter, cooler and since it has multiple taped primaries unlike the 2XX series you can avoid the need to use an autotransformer.
Growing up overseas using 120V appliances with autotransformers became a bit of a nuisance, I'd avoid that at any cost, but that's just me.
Growing up overseas using 120V appliances with autotransformers became a bit of a nuisance, I'd avoid that at any cost, but that's just me.
I see.. nothing irritates me more than a buzzing transformer, if i need to buy a new transformer ill certianly get a 3xx series.
See how my old one tests out on both channels, its used to running 12ax7's in aikido but now its going to run 6sn7's which run with a lot more current so well see how it copes.
Cheers
Craig
See how my old one tests out on both channels, its used to running 12ax7's in aikido but now its going to run 6sn7's which run with a lot more current so well see how it copes.
Cheers
Craig
My 2 bobs worth
Hi Craig
I used filament transformers from local electronics shop. 12Volt ones to supply home made pc boards sporting LM338k regulators no problems at all with hum and they can handle 5 amps each with a decent heatsink. i use one trans and one regulator per channel on my preamp which runs 2 6sn7's and one sl7 per side. I love overkill.. its a geeks paradise.
I built dual regulated B+ using one transformer but with chokes in parallel one for left and one for right channel
If you want a piccie of heater psu's let me know
Good luck
Nick
Hi Craig
I used filament transformers from local electronics shop. 12Volt ones to supply home made pc boards sporting LM338k regulators no problems at all with hum and they can handle 5 amps each with a decent heatsink. i use one trans and one regulator per channel on my preamp which runs 2 6sn7's and one sl7 per side. I love overkill.. its a geeks paradise.
I built dual regulated B+ using one transformer but with chokes in parallel one for left and one for right channel
If you want a piccie of heater psu's let me know
Good luck
Nick
Are you using tube rectifier with the tube regulated power supply? Normally if you do that it does not cause the tubes to make a thump on startup. If you are and it still does that, what circuit are you using? Perhaps it can be modded to de-thump it?
btw, good choice to go up to 6SN7s for the aikido. This will blow you away compared to 12ax7. That's what I did and I remember the "wow"
Best 6sn7 I found are the expensive and hard to get 1578 russian special tubes.
btw, good choice to go up to 6SN7s for the aikido. This will blow you away compared to 12ax7. That's what I did and I remember the "wow"
Best 6sn7 I found are the expensive and hard to get 1578 russian special tubes.
Psu
My psu goes like this: one 250mA tortech tran going into 2 5u4gb's then into a 10mh Choke which then feeds a 6080 12at7 5651 each channell.. I wouldnt build another preamp without regulated dc.. the heater boards i made do the job nicely.. I used to have (still do) a 12ax7/12at/12au7 preamp.. the 6sn7 walks on it for everything.. to the point now where i just dont like noval tubes (except maybe the 6dj8).. its octal for me.
Just about to start my dual monobloc parallel 300b's.... overkill? Of course but it keeps me off the streets.
cheers
My psu goes like this: one 250mA tortech tran going into 2 5u4gb's then into a 10mh Choke which then feeds a 6080 12at7 5651 each channell.. I wouldnt build another preamp without regulated dc.. the heater boards i made do the job nicely.. I used to have (still do) a 12ax7/12at/12au7 preamp.. the 6sn7 walks on it for everything.. to the point now where i just dont like noval tubes (except maybe the 6dj8).. its octal for me.
Just about to start my dual monobloc parallel 300b's.... overkill? Of course but it keeps me off the streets.
cheers
Duderduderini (big lebowski reference?)
Yes i was thinking of going regulated DC on heaters. got plenty of nice looking heatsinks to put regulators on. Even though apparently AC heaters when properly filtered and fed cause almost no audible hum i just feel better using some steady clean DC.
Yea put up a picture of the PSU's id be interested.
Beau2317
Yes i am using a tube rectifier (5z4), normally i dont think it would thump but in my old Aikido i decided that pretty regulator tubes would be a good idea. They take away any benefit of the of start of the rectifier when they srtike up.
Yea im really hoping the 6sn7 will be a better tube!
Cheers
Craig
Yes i was thinking of going regulated DC on heaters. got plenty of nice looking heatsinks to put regulators on. Even though apparently AC heaters when properly filtered and fed cause almost no audible hum i just feel better using some steady clean DC.
Yea put up a picture of the PSU's id be interested.
Beau2317
Yes i am using a tube rectifier (5z4), normally i dont think it would thump but in my old Aikido i decided that pretty regulator tubes would be a good idea. They take away any benefit of the of start of the rectifier when they srtike up.
Yea im really hoping the 6sn7 will be a better tube!
Cheers
Craig
Is your rectifier "striking" in the sense of making a flash when it starts?
It should not do that...things that might cause that are too high voltage, too much capacitance or load..what size capacitor do you have just after the rectifier?
I have an aikido with tube rectifier, regulator, and you can turn that on with the power amp on, and it just slowly starts making music when it powers up. I always thought that was one of the nice things about this design (as long as you put in all the protection resistors as on the PCB)
It should not do that...things that might cause that are too high voltage, too much capacitance or load..what size capacitor do you have just after the rectifier?
I have an aikido with tube rectifier, regulator, and you can turn that on with the power amp on, and it just slowly starts making music when it powers up. I always thought that was one of the nice things about this design (as long as you put in all the protection resistors as on the PCB)
Hmm, i only had about 0.033uf after each regulator tube. Sorry the correct term may not be striking but it seemed to fit.
No flash or anything, but when the rectifier warms up and allows 300vDC or more at its cathode the tube regulators have enough current to illuminate and kind of lock on to the voltage they were designed to hold. I say 300V because initially i used 2xVR150's stacked per channel to get my HT.
But on the scope the DC voltage at the anodes of the 12ax7s flew about for a split second before settling down again at the moment the regulator tubes lit up.
Dont know if this is normal behaviour? i just regarded it as the price i payed for purpleness that impressed people
Cheers
Craig
No flash or anything, but when the rectifier warms up and allows 300vDC or more at its cathode the tube regulators have enough current to illuminate and kind of lock on to the voltage they were designed to hold. I say 300V because initially i used 2xVR150's stacked per channel to get my HT.
But on the scope the DC voltage at the anodes of the 12ax7s flew about for a split second before settling down again at the moment the regulator tubes lit up.
Dont know if this is normal behaviour? i just regarded it as the price i payed for purpleness that impressed people
Cheers
Craig
Some heater boards
Hi Chris
I predate Lebowski on the use of the term but a great movie nonetheless. Thats how we spoke at uni waaay back in 1980.. thankfully terms such as dude came back into fashion to make me look hip. Thankfully also ,is that Flares did not come back into fashion.
Now down to geek business.
I have used these boards in my preamp now for 2 months it is a variation of a circuit that i found on the net which i will send you a link. The difference is that i didnt fit 10,000uf caps cause i had no room on the board. It is a slight variation of the circuit that is de rigeur for the LM338k and readily available as a datasheet download.
http://www.aaroncake.net/circuits/supply.asp thats the link i mentioned
here are the photos of my board
Hi Chris
I predate Lebowski on the use of the term but a great movie nonetheless. Thats how we spoke at uni waaay back in 1980.. thankfully terms such as dude came back into fashion to make me look hip. Thankfully also ,is that Flares did not come back into fashion.
Now down to geek business.
I have used these boards in my preamp now for 2 months it is a variation of a circuit that i found on the net which i will send you a link. The difference is that i didnt fit 10,000uf caps cause i had no room on the board. It is a slight variation of the circuit that is de rigeur for the LM338k and readily available as a datasheet download.
http://www.aaroncake.net/circuits/supply.asp thats the link i mentioned
here are the photos of my board
Attachments
and the last one
Here is the underside of the board.. i farmed board making out cause i was assured it would be done professionally.. as you can see its basically hand drawn with etch resistant pen... i may make my own bards up next.. i just mastered the dark art of board making.
the regulator is on a board when i was experimenting with an clc filter to see if hum could be reduced... it didnt make a difference. The first time i hooked it up, hum was noticable but of course i forgot to run a wire from the -ve to earth on the first tube in my amp (this board supplies 3 6sn7 heaters in parallel). once i ground the sucker it had no hum at all.
Thing i also did
1. placed a pga self adhesive heatsink on the to3 pakage.
2. Made a heatsink for the bridge rectifier of brass strip 20mm wide by 60 or so mm high.. attached a pga self adhesive heatsink wither side of the brass.
My pre amp power supply has an 80mm dc fan cooling it... the to3 does get hot as does the bridge.. the heat sink works but the fan reduced temp by half...
the transformer is 12v out.. i tried 9v but the lm338k needs minimun 3.5V voltage differential to regulate (ie with the trans tappings at 9v it wouldnt regulate )
if you need more help let me know.
Regards
Nick
Here is the underside of the board.. i farmed board making out cause i was assured it would be done professionally.. as you can see its basically hand drawn with etch resistant pen... i may make my own bards up next.. i just mastered the dark art of board making.
the regulator is on a board when i was experimenting with an clc filter to see if hum could be reduced... it didnt make a difference. The first time i hooked it up, hum was noticable but of course i forgot to run a wire from the -ve to earth on the first tube in my amp (this board supplies 3 6sn7 heaters in parallel). once i ground the sucker it had no hum at all.
Thing i also did
1. placed a pga self adhesive heatsink on the to3 pakage.
2. Made a heatsink for the bridge rectifier of brass strip 20mm wide by 60 or so mm high.. attached a pga self adhesive heatsink wither side of the brass.
My pre amp power supply has an 80mm dc fan cooling it... the to3 does get hot as does the bridge.. the heat sink works but the fan reduced temp by half...
the transformer is 12v out.. i tried 9v but the lm338k needs minimun 3.5V voltage differential to regulate (ie with the trans tappings at 9v it wouldnt regulate )
if you need more help let me know.
Regards
Nick
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