Thanks a lot Andrew!
Following your recommendation and accounting for others saying I'll probably go for a 250 VA transformer.
Regards,
Oleg
Following your recommendation and accounting for others saying I'll probably go for a 250 VA transformer.
Regards,
Oleg
Andrew is spot on.. But if cost is marginal the dual transformers will allow for mono blocs at the speakers reducing speaker wire length or even active speakers. That will make way more of a difference than changing from 200 to 400va... However that adds dual enclosure costs..
Hi Troy,
Thanks for suggestion. I plan to bi-amp my speakers, but will do it in two steps. First, one stereo amp, then the other one. I plan to place them near the speakers. I would not like to end up with 4 mono blocks or even 6 after I complete the center channel speaker...
I do not want to start a big discussion on it here but is there a big sonic difference between mono blocks and a stereo or it is mostly subjective, e.g. someone can hear the difference and someone can't? Unfortunately I do not have my own experience on that... I just want to build my entire system once and keep it for a long time, so making it right from the first attempt is the goal.
Regards,
Oleg
Thanks for suggestion. I plan to bi-amp my speakers, but will do it in two steps. First, one stereo amp, then the other one. I plan to place them near the speakers. I would not like to end up with 4 mono blocks or even 6 after I complete the center channel speaker...
I do not want to start a big discussion on it here but is there a big sonic difference between mono blocks and a stereo or it is mostly subjective, e.g. someone can hear the difference and someone can't? Unfortunately I do not have my own experience on that... I just want to build my entire system once and keep it for a long time, so making it right from the first attempt is the goal.
Regards,
Oleg
I cannot build a stereo amplifier as quiet as a mono-block amplifier. No matter how many different grounding schemes I have tried. It is more than 100 different grounding topologies for stereo so far.
My guess it probably will, so I will get some parts.
I must say its hard finding a nice looking spst power switch.
There are so many things that you don't think of until your at that point. Cost adds up in this hobby... But it's worth it.
It may be too late in your situation if you already have your chassis, but remember the power switch doesn't have to be on the front panel. Placing it on the back - even using a single inlet unit that combines a switch and a fuse - has merit depending on your aesthetic goals. That also reduces the length and complexity of the wiring and may require only some low voltage LED power fed to the front. Just an option to consider.
It sounds like your final system will have multiple amps, so you may end up using a power bar and not even need individual front panel power access.
Schurter makes some nice latching pushbutton power switches. They are pricey though. The last time I was shopping for power switches allied had some great deals.
exactly what i wanted!, the standard non led version is affordable..
The LED version is not 😱
http://www.digikey.com.au/product-detail/en/1241.6824.1124000/486-1439-ND/2096073
The system will only be stereo, however i wanted 2 cases with heatsinks. Just so i have the option to use them in future projects.
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OOPS - my bad 😱 Somehow got your posts mixed in with OlegSH. Sorry!
Did you look at the RS offerings?
Did you look at the RS offerings?
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Hi Oleg,
as Andrew already pointed out a monoblock approach is more quiet and power ratings he gave are perfect.
I would add that a monoblock build is the only supported one for the FEs.
In most cases a stereo build will do but hum is possible and the amp will not be as quiet as monoblocks.
My suggestion is to use two transformers (possibly around 200VA), nobody will stop you to have a monoblock approach in a single case, though. 😉
One cannot build a monoblock from a two channel amplifier.
A monoblock is ONE channel !
Putting in two transformers to power two isolated channels is a dual mono. That is not a monoblock.
A dual mono is afflicted with the same ground loop difficulties that a stereo amplifier has.
BTW,
a four secondary transformer achieves the same isolation of the two channels, as a pair of dual secondary transformers.
I would like to refer to a 4secondary as a dual mono build, but I don't think that would be universally accepted.
A 4 secondary is simply a stereo amplifier with isolated channels.
A monoblock is ONE channel !
Putting in two transformers to power two isolated channels is a dual mono. That is not a monoblock.
A dual mono is afflicted with the same ground loop difficulties that a stereo amplifier has.
BTW,
a four secondary transformer achieves the same isolation of the two channels, as a pair of dual secondary transformers.
I would like to refer to a 4secondary as a dual mono build, but I don't think that would be universally accepted.
A 4 secondary is simply a stereo amplifier with isolated channels.
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Was waiting for that Mr. T.😉
The post simply notes that load, common and ground (hot, neutral, ground) will resolve to a single AC feed in both dual mono and monoblock sets. On which side of the wall outlet that happens is the builder's option, but it is unavoidable. Getting the ground paths/isolation correct is of course tricky at times, but at some point even they will merge.
I'm only suggesting that from a physical construction/cost perspective, DM and MB may be quite similar, and the builder can consider whether the difference justifies the second chassis.
A stereo setup is a different animal.
The post simply notes that load, common and ground (hot, neutral, ground) will resolve to a single AC feed in both dual mono and monoblock sets. On which side of the wall outlet that happens is the builder's option, but it is unavoidable. Getting the ground paths/isolation correct is of course tricky at times, but at some point even they will merge.
I'm only suggesting that from a physical construction/cost perspective, DM and MB may be quite similar, and the builder can consider whether the difference justifies the second chassis.
A stereo setup is a different animal.
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It is the single shared Chassis, or the electrically separated dual Chassis, that makes the fundamental difference between Stereo (and multi-channel) and monoblock.
A monoblock is ONE amplifier inside a Chassis.
A multi-channel amplifier shares a Chassis. That Chassis is electrically common to all the contents.
Whether it has one transformer or ten transformers or isolated secondaries does not matter.
It's the Chassis and it's contents that determines monoblock or not.
A monoblock is ONE amplifier inside a Chassis.
A multi-channel amplifier shares a Chassis. That Chassis is electrically common to all the contents.
Whether it has one transformer or ten transformers or isolated secondaries does not matter.
It's the Chassis and it's contents that determines monoblock or not.
I hear what you are saying and am not disagreeing at all on the definitions and what they represent physically.
These are pictures of one (the same) amp build mounted in two distinct chassis styles. I'm merely trying to present usable construction options that may have nearly identical functional outcome to potential FE builders - not an attempt to jumble or mis-apply accepted terminology.
These are pictures of one (the same) amp build mounted in two distinct chassis styles. I'm merely trying to present usable construction options that may have nearly identical functional outcome to potential FE builders - not an attempt to jumble or mis-apply accepted terminology.
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Comparing the pros and cons of various approaches and having the plan to build at least 4 channels in total I would probably stick to the dual mono in a common chassis with single quad secondary transformer (will end up having 2 fully featured dual mono amplifiers to bi-amp two speakers). One of the manufacturers that I looked at claims that their transformers comply with Class II standard (double insulated as far as I understand) which would allow to never couple channels grounds to the chassis/safety ground. Also as pointed out somewhere else by AndrewT (if I am not mistaken) a higher power rating transformer has an advantage of smaller voltage drop under load if compared to a set of two half rated transformers.
Oleg
Oleg
P { margin-bottom: 0.21cm; } Before I order the transformers I also have another question. Would it be OK to use an extra set of four 4 Vac transformer secondaries in combination with four 24 Vac ones (with same current rating) in order to be able to adjust PSU output voltage for a 4 Ohm amplifier load with a simple switch (e.g. 24 Vac – 4 Vac = 20 Vac if 24 and 4 Vac secondaries connected serially but in reverce direction)? Are there more problems than the added copper losses?
The 20 + 4 combination is of course an obvious solution but who knows... may be I would soon decide to build something else which would demand a higher voltage PSU🙂
The 20 + 4 combination is of course an obvious solution but who knows... may be I would soon decide to build something else which would demand a higher voltage PSU🙂
the switchable supply rail voltage is a good idea if you can keep the secondary loop areas small.
I don't like the reverse phase to lower the secondary. It works, but it increases the source impedance as well as the copper losses, due to the increased resistance of the secondary windings. Into a 4ohms load the speaker is going to demand more current and the reverse phase has put extra resistance in line instead of reducing the resistance.
Adding voltage for an 8ohms loading is OK. That works well.
You can reduce the secondary voltage by adding primary turns.
I don't like the reverse phase to lower the secondary. It works, but it increases the source impedance as well as the copper losses, due to the increased resistance of the secondary windings. Into a 4ohms load the speaker is going to demand more current and the reverse phase has put extra resistance in line instead of reducing the resistance.
Adding voltage for an 8ohms loading is OK. That works well.
You can reduce the secondary voltage by adding primary turns.