My turtle finally got a proper home.
The buffer boards are impressive, shunts are really stable and easy to dial in. Nice work Zenmod! The only MCK-cap i could fit in the regulator was 0.15 uF (my small stash is wimas), should I try to find a larger one?
There is remote control of volume and orderly power on/off for preamps, poweramps and tv.
No mosfets wasted, they are all matching rejects, all design pretty much dictated by what I had in left over drawer such as old arduino and motor pot from old volume control.
I call the arduino shield (more fun in languages where turtles have shields) Mimmi in honour of my (male) water turtle.
Soundwise this rocks, with really well articulated bass. I have get some hum at low attenuation, but it dissapears with more attenuation so might be in preceding stage? Will try better shielding in chassis, but problem appears above reasonable listening levels so for now I will just enjoy this amazing piece of kit!
Thanks again for sharing this project with us all, it rocks!
The buffer boards are impressive, shunts are really stable and easy to dial in. Nice work Zenmod! The only MCK-cap i could fit in the regulator was 0.15 uF (my small stash is wimas), should I try to find a larger one?
There is remote control of volume and orderly power on/off for preamps, poweramps and tv.
No mosfets wasted, they are all matching rejects, all design pretty much dictated by what I had in left over drawer such as old arduino and motor pot from old volume control.
I call the arduino shield (more fun in languages where turtles have shields) Mimmi in honour of my (male) water turtle.
Soundwise this rocks, with really well articulated bass. I have get some hum at low attenuation, but it dissapears with more attenuation so might be in preceding stage? Will try better shielding in chassis, but problem appears above reasonable listening levels so for now I will just enjoy this amazing piece of kit!
Thanks again for sharing this project with us all, it rocks!
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brave and bold!
MKC is sorta cherry on top, value not critical at all - just use whatever you have
regarding hum - investigate any possible source of magnetic field around - amps or whatever - move further whatever looks suspicious
rotate both Donuts to see can you minimize hum, then you'll see are they critical
last thing you need to try moving both Donuts out of case, for test
I'm using Trafomatic made 30VA custom xformer , static and magnetig shield, in Modushop 280mm deep case, and there is no hum even in traces
both Mazeppa and Bubba Bob are having same xformers in their Iron Pumpkins and I believe they both are happy too
for instance - Papa's Plankey is exhibiting some hum, when used with SE inputs, even if Donuts are practically in other room, they're so nasty
That is comically far
Will try playing around with the transformers a bit - my turtle has had the hum since the smaller donut came into the picture, with the larger one (stolen from dual dcb1-project) it has been totally quite. Since they are ridiculously oversized, might be decent idea to get custom smaller one with all needed secondaries.
With current gain structure I listen at such high attenueation (volume below 50% in all circumstanses other than disco at childrens party) that the hum is completely inaudible even with ear next to speaker (this has not happened earlier in my system) so the hum-hunt will wait. I have to spend time listening to my amazing new preamp!
Thanks again, your stuff is really, really nice=)
Will try playing around with the transformers a bit - my turtle has had the hum since the smaller donut came into the picture, with the larger one (stolen from dual dcb1-project) it has been totally quite. Since they are ridiculously oversized, might be decent idea to get custom smaller one with all needed secondaries.
With current gain structure I listen at such high attenueation (volume below 50% in all circumstanses other than disco at childrens party) that the hum is completely inaudible even with ear next to speaker (this has not happened earlier in my system) so the hum-hunt will wait. I have to spend time listening to my amazing new preamp!
Thanks again, your stuff is really, really nice=)
Hi Torb,
The large Toroidy is nicely encapsulated in iron and has also internal shielding.
The small one has non of that.
I would try to put the small one vertical against the side of the case and
put an iron plate around it,
attention: don't let the transformer bolt touch on both sides the iron, that's like creating a short on your transformer winding.
The large Toroidy is nicely encapsulated in iron and has also internal shielding.
The small one has non of that.
I would try to put the small one vertical against the side of the case and
put an iron plate around it,
attention: don't let the transformer bolt touch on both sides the iron, that's like creating a short on your transformer winding.
Hi danny!
Thanks for replying! Your implementation looks really neat=)
I'm reluctant to drill more holes in the chassis - the panels are a bit unpractical to remove and I don't want to spread metal pieces in the chassis. For simplicity I ordered a new transformer from toroidy with all the needed secondaries. It will be of 45 VA, the current ones are someting like 150 together.
Do you have any hum? What kind of system do you have? Following my turtle is the diy vfet-kit-amp (which is great!) and DTQWT mk II from Troels. I have always had some hum, and this configuration has the least thus far. if it is possible to get less, awesome, but not a dealbreaker. As it is, I already have great disco sessions with my three-years old=)
Best regards!
Thanks for replying! Your implementation looks really neat=)
I'm reluctant to drill more holes in the chassis - the panels are a bit unpractical to remove and I don't want to spread metal pieces in the chassis. For simplicity I ordered a new transformer from toroidy with all the needed secondaries. It will be of 45 VA, the current ones are someting like 150 together.
Do you have any hum? What kind of system do you have? Following my turtle is the diy vfet-kit-amp (which is great!) and DTQWT mk II from Troels. I have always had some hum, and this configuration has the least thus far. if it is possible to get less, awesome, but not a dealbreaker. As it is, I already have great disco sessions with my three-years old=)
Best regards!
Hi Torb,
An Audio Toroidy is a good start to bring the hum down.
My system doesn't have any hum or hiss, this is with ears close to the drivers.
My system is now:
Soekris DAC -> Iron Pumpkin -> Alpha20 -> RefSpeaker2
Things I did to kill the hum:
- Pumpkin and Alpha20 amplifier are built as dual mono's,
- circuit/signal ground connected to earth through 10 ohm resistor or NTC
- transformers with screening and shields
I did get hum (up to 5-10cm from drivers) in a test setup:
Iron Pumpkin with open case, wooden board with DAC on top of it,
transformer of DAC close to AVC, so there was only some wood between AVC and a transformer.
The diy vfet-kit-amp will be great, my friend Bernard has built the Pass Sony VFET and it sounds fabulous.
The Iron Pumpkin still amazes me in bringing out the music with all the details,
all beautiful layered which makes it easy to "see" into the music.
This is a preamp that makes my system much better
Grts,
Danny
An Audio Toroidy is a good start to bring the hum down.
My system doesn't have any hum or hiss, this is with ears close to the drivers.
My system is now:
Soekris DAC -> Iron Pumpkin -> Alpha20 -> RefSpeaker2
Things I did to kill the hum:
- Pumpkin and Alpha20 amplifier are built as dual mono's,
- circuit/signal ground connected to earth through 10 ohm resistor or NTC
- transformers with screening and shields
I did get hum (up to 5-10cm from drivers) in a test setup:
Iron Pumpkin with open case, wooden board with DAC on top of it,
transformer of DAC close to AVC, so there was only some wood between AVC and a transformer.
The diy vfet-kit-amp will be great, my friend Bernard has built the Pass Sony VFET and it sounds fabulous.
The Iron Pumpkin still amazes me in bringing out the music with all the details,
all beautiful layered which makes it easy to "see" into the music.
This is a preamp that makes my system much better
Grts,
Danny
I have to say that it's the best transformer I've heard, and it measures
very well too.
Hi again!
I got a much smaller and canned transformer with needed secondaries. Hum went down to the point where it can only be heard at speaker-destroying volume settings - no longer relevant=)
I used to like playing in symphony orchestras when I was young, but I have never enjoyed listening to symphonic music at home. With current setup iron pumpkin -> diy vfet2 -> Troels DTQWT mkII I do for the first time enjoy such music at home. Your gear is great, and brings pleasure. Thanks!
Have you by the way tried putting a burning amp output stage at each phase of the autoformer out? Like bridged integrated?
I got a much smaller and canned transformer with needed secondaries. Hum went down to the point where it can only be heard at speaker-destroying volume settings - no longer relevant=)
I used to like playing in symphony orchestras when I was young, but I have never enjoyed listening to symphonic music at home. With current setup iron pumpkin -> diy vfet2 -> Troels DTQWT mkII I do for the first time enjoy such music at home. Your gear is great, and brings pleasure. Thanks!
Have you by the way tried putting a burning amp output stage at each phase of the autoformer out? Like bridged integrated?
I'm glad to read that!
enjoy as much you can
regarding bridged - everything is possible, when you have fully balanced/truly differential output, with low Rout
though - I didn't tried exactly that, simply because I don't have need for much power and, as you know, it's hard/not exactly practical to make bridged amp with low power
in fact, it's easy, but low on my list
enjoy as much you can
regarding bridged - everything is possible, when you have fully balanced/truly differential output, with low Rout
though - I didn't tried exactly that, simply because I don't have need for much power and, as you know, it's hard/not exactly practical to make bridged amp with low power
in fact, it's easy, but low on my list
I've lived for years with proper balanced equipment, while working in local Radio-station. So, with that experience, my stance is that pursuing "balanced" is fully justified only if going balanced all the way - means that all imprtant sources must be balanced
that means - properly balanced in concept and construction, not as majority of nowadays thingies are - inherently SE with some additional gizmo patch-like stage , put there just to add inverted phase
and - also taking in account that one really prefers THD Spectra naturally resulting from balanced - pretty much non-existing 2nd harmonic and existing 3rd (all even, all odds, same logic)
though, I had some success in forcing bridged gadgets to have dominant 2nd, but that's certainly exception from rule
of course, one is always welcome to buy Papa's **.8 amp, or even XS Amp, and enjoy all blessings which deliberately spoiled symmetry can bring
btw. I promised "small" Babelfish XJ iteration to try soon, even have FE pcbs made, and that one should be same way 2nd dominant as first (big) iteration
problem - my twin was never born
that means - properly balanced in concept and construction, not as majority of nowadays thingies are - inherently SE with some additional gizmo patch-like stage , put there just to add inverted phase
and - also taking in account that one really prefers THD Spectra naturally resulting from balanced - pretty much non-existing 2nd harmonic and existing 3rd (all even, all odds, same logic)
though, I had some success in forcing bridged gadgets to have dominant 2nd, but that's certainly exception from rule
of course, one is always welcome to buy Papa's **.8 amp, or even XS Amp, and enjoy all blessings which deliberately spoiled symmetry can bring
btw. I promised "small" Babelfish XJ iteration to try soon, even have FE pcbs made, and that one should be same way 2nd dominant as first (big) iteration
problem - my twin was never born
These are good experiences hard earned, thanks for sharing. I'm currently limited to digital music and using a properly balanced dac (one chip/phase.) I haven't yet found out what kind of distortion I like, but going for bridged followers would teach me something about this and better my gain structure (with ~16 dB of gain in poweramps, I often listen with the pumpkin at maximum attenuation, so removing poweramp gain bur using both phases should put me more in the middle of possible attenuation settings and be more child safe.)
I'm thinking of something like bridged crippled f4:s, this could be a good project for next autumn=)
Missing twin problem is serious one, this hobby has to be served cold! Getting one thing done every 2 years between family, work, research etc. seems reasonable=)
I'm thinking of something like bridged crippled f4:s, this could be a good project for next autumn=)
Missing twin problem is serious one, this hobby has to be served cold! Getting one thing done every 2 years between family, work, research etc. seems reasonable=)