I have no safety ground connection in the outlet in my living room. Only in the kitchen. So using tube amps I have to be sure that the wiring is safe. The PSU built up on a wood base is quite safe as there is no metal case around it. So even if I had safety ground I would not know where to connect it.
I know that some HiFi people wants a solid earth connection where it really goes to the ground via a long metal spear. But this is more to have a good reference among HiFi components to get less hum. Not so much for safety reasons. Some try to use the radiator in the central heating when living in apartments but this can be a bad idea. A fault can cause dogs, cats etc. to be killed in the other apartments…….and maybe humans…..
I know that some HiFi people wants a solid earth connection where it really goes to the ground via a long metal spear. But this is more to have a good reference among HiFi components to get less hum. Not so much for safety reasons. Some try to use the radiator in the central heating when living in apartments but this can be a bad idea. A fault can cause dogs, cats etc. to be killed in the other apartments…….and maybe humans…..
Probably codes only mandated ground in Kitchen when house was built. That's usually where the "innovations" start, since it is considered a wet area.
If that neutral wire is only used in conjunction with a single phase (very important!!!) and terminates in the distribution panel it is possible to use the neutral as ground. If the same neutral is shared between 2 different phases in different outlets a ground failure will turn the outlets in the other circuit into 240V outlets. This arrangement is not technically correct as it doesn't serve as a safety measure (to protect people from shocks) but will supply a common ground reference in case you need.
I am not sure how electricity is distributed in EU, though. I though it was all 240V. 240V in the US is done by 2 inverted phases. 120V is done by a phase and a neutral. It's not the best system in the world (by a long shot) because its standard was defined very early in history.
If that neutral wire is only used in conjunction with a single phase (very important!!!) and terminates in the distribution panel it is possible to use the neutral as ground. If the same neutral is shared between 2 different phases in different outlets a ground failure will turn the outlets in the other circuit into 240V outlets. This arrangement is not technically correct as it doesn't serve as a safety measure (to protect people from shocks) but will supply a common ground reference in case you need.
I am not sure how electricity is distributed in EU, though. I though it was all 240V. 240V in the US is done by 2 inverted phases. 120V is done by a phase and a neutral. It's not the best system in the world (by a long shot) because its standard was defined very early in history.
I should probably contact an Electrician before I experiment. There is an outdoor outlet at the balcony and this outlet has Ground. So a cable with all 3 connection is somewhere in the walls. At some place the Ground and Neutral must have a galvanic connection. Maybe at the transformer station or maybe at a central place in the building where the main cables are going in. We have 400 VAC between two phases. It can be used for the electric stove or large washing machines. Only the kitchen has these large outlets with three phases. It has 16A slow fuses pr. phase so have to be careful.
Hi Rafa, and thanks for your explanation, I've finally got there- there is NO 15wpc stereo output, just mono, no good to me i'm afraid.
My speakers are all 8ohm which makes things easier, and interestingly, two are 86db, and one nice and sensitive at 95db.
So it looks like I might need a pre amp with gain (around 6db).
Someone mentioned a whammy, but I looked and that's a headphone amp, so how does that help me? Also it's a way more complicated build than the ACA.
I would be listening to line-level sources, so.......
Despite the fact that I feel I might be left a bit short (yes I know these are just numbers, but I'm used to powerful amps, my main setup at home is a Quad 909 with 99 pre amp, driving Spendor A6 speakers), I'm now tempted to build this amp in its 8w stereo guise and listen to it (it'll have to be on the sensitive speakers).
Shame Nelson didn't design a more powerful version.
Thanks everyone who chipped in though, it's all been helpful.
Oh by the way Rafa, en Espanyol si te apetece, te entiendo.
Meper, there is absolutely nothing to be gained by experimenting with live high voltage wires. Calling an electrician is probably the way to go, even better you can explain to him/her in detail what it is that you want to be done and get an estimate.
I did check my house, the basement where the circuit breakers are and the mains enter the house. There is a prominent very large gauge (4 ga. ?) unshielded woven steel cable that sinks into the basement wall. I also see there is one at least 14 ga green shielded wire that connects to it via a screwed connection. This disappears into the basement ceiling rafters. I am pretty sure this is the house ground terminal (the unshielded steel terminal coming out of the circuit breaker box). I assume that somewhere in your apartment or in your building you have a similar arrangement. An electrician is the right person to go talk with. Plan what you want to have installed. If you want a dedicated ground connection (only for ground) in your living room you probably can have it. All the best.
I did check my house, the basement where the circuit breakers are and the mains enter the house. There is a prominent very large gauge (4 ga. ?) unshielded woven steel cable that sinks into the basement wall. I also see there is one at least 14 ga green shielded wire that connects to it via a screwed connection. This disappears into the basement ceiling rafters. I am pretty sure this is the house ground terminal (the unshielded steel terminal coming out of the circuit breaker box). I assume that somewhere in your apartment or in your building you have a similar arrangement. An electrician is the right person to go talk with. Plan what you want to have installed. If you want a dedicated ground connection (only for ground) in your living room you probably can have it. All the best.
Just for your curiosity, and doesn't help MEPER, because every country is different, but in the US:
1- The bare stranded wire is the neutral coming from the utility company. It is grounded at the transformer.
2- To save money (for the utility company, as they can now save on grounding at the transformer) and as excuse for safety (not completely justified) you also must have 1 to 3 ground rod(s) close to the electric panel and connecting somehow (usually at the panel) to their stranded wire. This is relatively new code, I don't know for certain how old this requirement is, probably started at the same time as grounding receptacles became part of the code, probably late 60's.
3- At the panel your neutral and ground wires coming from the house are connected together and to the stranded wire /ground rods.
4- The thick (it should be 8 gauge bare) wire disappearing from your panel by itself is going to ground your gas (black pipe) and water lines (if copper).
And yes, if you're not familiar with installations, call a technician. Not that you're going to die from mains electrocution (believe me ... you're not), but it might be really easy to mess up and end up and either damage appliances or burn your house down, especially in countries where houses are made of wood (and then you might certainly die...)
Semmyroundel, there are any number of preamps, including those labeled "headphone amps" that can serve your purposes very well and give you 6 dB gain. You have to do your due diligence and check the net to find them. Let me suggest that you check two offerings of Schiit audio, I am not connected with them, just like their name and their prices:
1. Jotunheim, a DAC /headphone amp (can be had without the DAC) with balanced outputs. Swith selectable gain as follows, high gain of 14dB, low gain of 6dB. The low gain is more defined and precise.
2. Asgard 2 headphone amp with preamp outputs switch selectable as follows: high gain 15.6dB, low gain 3.5dB.
Both of these can be had with UK specific plugs and voltages. I imagine there is any number of other similar products out there, you just have to find them.
1. Jotunheim, a DAC /headphone amp (can be had without the DAC) with balanced outputs. Swith selectable gain as follows, high gain of 14dB, low gain of 6dB. The low gain is more defined and precise.
2. Asgard 2 headphone amp with preamp outputs switch selectable as follows: high gain 15.6dB, low gain 3.5dB.
Both of these can be had with UK specific plugs and voltages. I imagine there is any number of other similar products out there, you just have to find them.
I built v1.6 a week ago. What a sweet little amp. Great detail and the bass is amazing. I don't blast music any more and I can't believe this drives my MMGs to a satisfying level. I've had a rash of amps pass through this system and this rivals the best I've had (Audio Research CA50 and Pass Aleph 5 come to mind). I'm thinking of buying another and running them in parallel mono mode.
It is an outstanding amp. So good, in fact, that I decided to give them (2 monoblocks) the Extreme Mod treatment; they are so worth it.
Parallel mono is the way to go; half the output impedance (double the damping factor), so the feedback can be reduced / the gain increased to 14dB. In my opinion, with 14dB of gain, you get everything you need to avoid the pre-amp altogether.
Wondering how you reduce the feedback. Also, it will be much appreciated if you point me toe the "Extreme Mod" you mentioned.
I'm using my MacBook Air running Audirivana/TIDAL via USB into a Benchmark DAC2 HGC into the ACA using homemade Mogami cables (better than the Cardas Neutral References I sold...) via Kimber 8TC to the MMGs. A Sunfire True Sub rounds it out. Power is from an industrial 2KVA isolation transformer on a dedicated 20A line.
I'm using my MacBook Air running Audirivana/TIDAL via USB into a Benchmark DAC2 HGC into the ACA using homemade Mogami cables (better than the Cardas Neutral References I sold...) via Kimber 8TC to the MMGs. A Sunfire True Sub rounds it out. Power is from an industrial 2KVA isolation transformer on a dedicated 20A line.
I have posted the photos probably 3-4 weeks ago, of what I did so far. I am waiting for some parts to arrive; probably 2-3 weeks - then I will finalize the latest set of mods and will post again. I believe in the shortest possible signal path with an absolute minimum of gain stages, with the last one working in pure class A, single-ended.
The feedback resistor can be increased from 39K to 68K to provide more gain.
The feedback resistor can be increased from 39K to 68K to provide more gain.
What happens to the input impedance of the amplifier in the Parallel Input/Parallel Output mono mode (last table on the right of this diagram)?:
https://cdn.shopify.com/s/files/1/1006/5046/files/ACA_Monoblock_Operation_RevA.pdf
Might be something to consider in overall system compatibility. I would also edit that document with an “Input impedance “ row if clarification is in order.
Best,
Anand.
https://cdn.shopify.com/s/files/1/1006/5046/files/ACA_Monoblock_Operation_RevA.pdf
Might be something to consider in overall system compatibility. I would also edit that document with an “Input impedance “ row if clarification is in order.
Best,
Anand.