While assembling following one set of schematics i was supplied with a few parts i purchased i stumbled across the error on the output tubes....who can spot it? glad i sat down tonight to compare the Mk2 schematic that i had the the Mk2.3 i downloaded off here thanks to Ralph!
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Ahh so i could have left it the other way! I purchased a box of parts that had those schematics included Ralph and and started working from them but after reading thru this forum found the 2.3 plans and decided to run with them, excluding the A/AB switch, i do have one question i cant find an answer for, and that is what value meter is used for DC balance? Getting closer to powering up and running some tests!
Team, some help please, have finished building one of these up, and i can power up, both power supplies working as they should, added tubes and then connected speaker and a source but i only get a very faint output when the input is at full (2v) have double and triple checked the schematic and cant see anything i may have done incorrectly! Any pointers greatly appreciated!
Thanks Banat, I have double checked that and all connected correctly, I have 160v floating supplies and the other supplies is 350v and 325v tho the negative supplies are both -350v so don't know if that would make any difference? And one question for a newbie, does it make any difference in the way section one or two of the valve are connected?
AtmaSphere M60
After lurking on diyAudio for many years and enjoying the many ideas and diverse approaches to audio it has presented, I now have a bit of time to participate.
I have always leaned towards valve audio and building an OTL amp has appealed (perhaps irrationally!) for some time. A review of OTL technology suggested that the circlotron could be best for me as it can provide stability with decent power output. I came across the AtmaSphere M60 that Ralph generously offered to non-commercial builders and was impressed by its elegant simplicity. After reading this thread, this had to be the one for me!
I plan to build 2 monoblock amps, each using 2 separate 100V toroids for the bridge supplies (50+50V toroids are far easier to get than 100+100V) with 10 6AS7 per monoblock. The driver circuit will remain M60 with no Class AB option.
Reading this thead, it looks as if the demands on each bridge transformer are fairly light - around 2A seems adequate. Of course, a larger transformer would hold the volts up better under load, but how large is good without being OTT? 2A means a 200 VA transformer. 300 VA looks reasonable and won't break the bank (| 2 Output Toroidal Transformer, 300VA, 2 x 50V ac |). Going up to 500 VA adds another £10 per item but is there any benefit?
Tim
After lurking on diyAudio for many years and enjoying the many ideas and diverse approaches to audio it has presented, I now have a bit of time to participate.
I have always leaned towards valve audio and building an OTL amp has appealed (perhaps irrationally!) for some time. A review of OTL technology suggested that the circlotron could be best for me as it can provide stability with decent power output. I came across the AtmaSphere M60 that Ralph generously offered to non-commercial builders and was impressed by its elegant simplicity. After reading this thread, this had to be the one for me!
I plan to build 2 monoblock amps, each using 2 separate 100V toroids for the bridge supplies (50+50V toroids are far easier to get than 100+100V) with 10 6AS7 per monoblock. The driver circuit will remain M60 with no Class AB option.
Reading this thead, it looks as if the demands on each bridge transformer are fairly light - around 2A seems adequate. Of course, a larger transformer would hold the volts up better under load, but how large is good without being OTT? 2A means a 200 VA transformer. 300 VA looks reasonable and won't break the bank (| 2 Output Toroidal Transformer, 300VA, 2 x 50V ac |). Going up to 500 VA adds another £10 per item but is there any benefit?
Tim
it´s your money and your decision
but what see there, can be described as unneccessary iron-phobia.
you can make amp from almost anything, but some decisions give more "pita" than others. otl are picky about speakers
you would be better with hybrid amp, where pre-tubes have entire gain=sound signature ; and fets just follows signal, giving max current gain, (no coloration at all).
but what see there, can be described as unneccessary iron-phobia.
you can make amp from almost anything, but some decisions give more "pita" than others. otl are picky about speakers
you would be better with hybrid amp, where pre-tubes have entire gain=sound signature ; and fets just follows signal, giving max current gain, (no coloration at all).
That is a VERY strange comment, and not true at all.
I have build a very well behaving OTL with NO feedback and NO stability problems:
6C33 Circlotron
I have build many hybrid amps (manufactured and sold too in fact many moons ago), and though they can be very good, IMHO no match for a full blown tube OTL (actually not much is)
I understand your view. I have built many amps over the years, PP, SE, hybrid, bipolar, MOSFET but have never tried OTL. I realise OTL like the bumblebee is a functional impossibility and yet they exist and people love the sound. I'm up for a challenge so I'm giving OTL a shot. Next project is one of Menno Van der Veen's Trans amps using GU50s. This like the OTL is designed to minimise O/P transformer influence and I'm looking forward to comparing the technologies.
That is a VERY strange comment, and not true at all.
I have build a very well behaving OTL with NO feedback and NO stability problems:
6C33 Circlotron
Just took a look at your Beast thread - most impressive! The OTL designs I looked at first featured 6C33 but I must admit to being put off by the heat and longevity issues. It seems commonly recognised that 6C33 OTLs need a long (250hrs or more) break in time and at least 20mins warm up before they sing. Is this a 6C33 thing or is this common with any OTL amp?
I am leaning towards using one 500VA 50+50V toroid per phase i.e. two of these per monoblock. RS do them for only £10 more than their 300VA equivalent so it should provide a stiff low impedance for my 10 6AS7 O/P devices with minimal crosstalk between phases. Another 6+6V 200VA toroid per phase for the 6AS7 heaters and 2 back-to-back 6+6V 50VA toroids for the driver heater & HT. A festival of toroids but no OPT in sight
Tim