Hi,
No. In fact its good as I rate chips only good into 8R loads
as ideally really more suitable for 16 ohm reactive loads.
Go on the small side for the recommended 8 ohm PSU VA size.
Expect a little over half power of the chip amp rating into 8R.
(not that the chip amp can provide said power into 8 ohm reactive).
rgds, sreten.
No. In fact its good as I rate chips only good into 8R loads
as ideally really more suitable for 16 ohm reactive loads.
Go on the small side for the recommended 8 ohm PSU VA size.
Expect a little over half power of the chip amp rating into 8R.
(not that the chip amp can provide said power into 8 ohm reactive).
rgds, sreten.
Last edited:
Hi Sreten,
Why do you recommend a smaller VA trans.. I'm thinking since the power rating will drop compared with a 8R load.. should a higher VA be a better way to go...
Thanks
Why do you recommend a smaller VA trans.. I'm thinking since the power rating will drop compared with a 8R load.. should a higher VA be a better way to go...
Thanks
For the last several months I have been driving my huge vintage 15 Ohm Tannoy Yorks with a very inexpensive little T2020 amp and they work amazingly together. In fact I have relegated my old McIntosh SS amp into storage.
I purchased the T2020 originally to drive a pair of Realistic Minimus speakers and just out of curiosity hooked up my old Tannoys, not expecting much. Well, I was amazed.
The previous week I got a good offer on the Tannoys and almost sold them....but not quite yet!
Thanks for the advice.. Good point about having to drive an 8 ohm spk maybe ..later on.. 
It is just an option to use a smaller VA transformator.
I would not do that.
It will not hurt
allso, what if you later would like to drive 8 ohm spekaers with the amp, but got a low VA traffo? yup, ain't gona work well.
So just go with the bigger traffo.
Hi,
Like I said, someone will always say go bigger, whatever choice you make.
Why not add bigger caps than you need as well, and while your at bigger
heatsinks and a bigger more expensive case. Why not ? It doesn't hurt ...
Design by oversizing, as bigger is better, but how big
being an openended question, doesn't appeal to me.
rgds, sreten.
Like I said, someone will always say go bigger, whatever choice you make.
Why not add bigger caps than you need as well, and while your at bigger
heatsinks and a bigger more expensive case. Why not ? It doesn't hurt ...
Design by oversizing, as bigger is better, but how big
being an openended question, doesn't appeal to me.
rgds, sreten.
Have you looked at this? http://www.diyaudio.com/forums/mult...much-voltage-power-do-your-speakers-need.html
With my 15 OHM speakers hooked up to my 2020 chip amp they only draw 0.4v. Doing the math this works out to .085 watts at serious listening levels.
yes i know that.
even so i would prefer have and not need, then need and not have..
There IS a limit where having bigger than needed is useless.
But in this case, 15 ohm speakers are less common than 8 ohm ones i think.
Sure, if this amplifier will surely never need to drive an 8 ohm speaker, then a smaller traffo is okay.
But.. what if not? the chip can handle an 8 ohm load, so why not just size everything to enable it to do so ?
That is what does not hurt at all.
Going for a 400 VA psu would be the pointless thing.
even so i would prefer have and not need, then need and not have..
There IS a limit where having bigger than needed is useless.
But in this case, 15 ohm speakers are less common than 8 ohm ones i think.
Sure, if this amplifier will surely never need to drive an 8 ohm speaker, then a smaller traffo is okay.
But.. what if not? the chip can handle an 8 ohm load, so why not just size everything to enable it to do so ?
That is what does not hurt at all.
Going for a 400 VA psu would be the pointless thing.
From Lenard Audio, a briefing on how to make a chip amp drive like a tube amp:
However, if you got droopy treble from using full band current drive above, here is a different option for current drive at only the bass.
From the JLH amplifier schematic of 1969, see component C2, sized to approximately 2500u if driving 16 ohm speakers. Carefully chosen roll-off has a current drive effect potentially useful for bass extension. Likewise, that approach works fine with chip amplifiers too and it installs inexpensive speaker protection, which is not included within the chip. There is no mystery why the update version has ordinary sound but the original has really rockin bass--that difference is C2.
Question:
How much output power does "SET 2A3 amp" have into 16 ohm speakers?
However, if you got droopy treble from using full band current drive above, here is a different option for current drive at only the bass.
From the JLH amplifier schematic of 1969, see component C2, sized to approximately 2500u if driving 16 ohm speakers. Carefully chosen roll-off has a current drive effect potentially useful for bass extension. Likewise, that approach works fine with chip amplifiers too and it installs inexpensive speaker protection, which is not included within the chip. There is no mystery why the update version has ordinary sound but the original has really rockin bass--that difference is C2.
An externally hosted image should be here but it was not working when we last tested it.
Question:
How much output power does "SET 2A3 amp" have into 16 ohm speakers?
based on more ampere for low imp speaker load, I would say reality is mostly the opposite
in general you will have to lower VA rating to achieve this
you dont need to change VA ratings. you only need to change voltage.
for low impedance load, lower the voltage to get more current.
for higher impedance load, higher voltage. (within specs)
VA is a somewhat terrible way to judge transformers, since manufacturers sometimes test with secondaries paralleled (makes cost look lower).
I'd much rather judge the transformer by amperage, which relates directly to bass quality and ripple performance. True enough that 16 ohm speakers need only half the amperage. I certainly wouldn't reduce it--I'd leave it powerful enough to drive 8 ohm speakers and simply enjoy lower ripple performance and better bass when the amplifier happens to drive a lighter load.
Now for voltage, most people max out the chips anyway or come close to it. It is probably because the most popular chips have a limiter we'd like to dodge. Anyway, I don't suggest increasing transformer voltage at all. Most examples are already maxed out.
VA difference? Not practically very different.
Amplifier? Quite different. . .
The 16 ohm speakers of yesteryear have limited power handling capacity and overly tight dampening making a tube amp's low power and current drive (looser electronic dampening) fairly ideal. However, a chip amp with some form of current drive adjustment could do the job. I mention some of that in post 15.
Here's some more.
Parallel amplifiers (with ballast resistors) and bridge amplifiers have looser electronic dampening. You can further help the sound a bit with a CRC power supply.
A bridge amplifier with a big capacitor series to the woofer (or the entire speaker), is a low loss simple way to current drive the bass. Now the impression of a tube amp comes down to whatever you put at the input of the amp.
Okay, here's an option:
Blarebuster or lightspeed attenuator or 6n3p buffer
OP275 Bridge adapter
4 of LM1875 chips or 8 of LM1875 chips for more lavish sound of bridged parallel.
CRC power supply
Simpler option (35 watts per channel):
MooseFet Preamp
Blarebuster
TDA7294 Stereo
CRC power supply
Very simple option (12 watts per channel):
Blarebuster
LM1875 stereo (with 18+18vac transformer)
CRC power supply
*can add the simple clipnipper for headroom management
*could do LM1875 parallel amplifiers (very easy) for a "darker voice" sound; however, you still get only 12 watts per channel when using 16 ohm speakers.
I'd much rather judge the transformer by amperage, which relates directly to bass quality and ripple performance. True enough that 16 ohm speakers need only half the amperage. I certainly wouldn't reduce it--I'd leave it powerful enough to drive 8 ohm speakers and simply enjoy lower ripple performance and better bass when the amplifier happens to drive a lighter load.
Now for voltage, most people max out the chips anyway or come close to it. It is probably because the most popular chips have a limiter we'd like to dodge. Anyway, I don't suggest increasing transformer voltage at all. Most examples are already maxed out.
VA difference? Not practically very different.
Amplifier? Quite different. . .
The 16 ohm speakers of yesteryear have limited power handling capacity and overly tight dampening making a tube amp's low power and current drive (looser electronic dampening) fairly ideal. However, a chip amp with some form of current drive adjustment could do the job. I mention some of that in post 15.
Here's some more.
Parallel amplifiers (with ballast resistors) and bridge amplifiers have looser electronic dampening. You can further help the sound a bit with a CRC power supply.
A bridge amplifier with a big capacitor series to the woofer (or the entire speaker), is a low loss simple way to current drive the bass. Now the impression of a tube amp comes down to whatever you put at the input of the amp.
Okay, here's an option:
Blarebuster or lightspeed attenuator or 6n3p buffer
OP275 Bridge adapter
4 of LM1875 chips or 8 of LM1875 chips for more lavish sound of bridged parallel.
CRC power supply
Simpler option (35 watts per channel):
MooseFet Preamp
Blarebuster
TDA7294 Stereo
CRC power supply
Very simple option (12 watts per channel):
Blarebuster
LM1875 stereo (with 18+18vac transformer)
CRC power supply
*can add the simple clipnipper for headroom management
*could do LM1875 parallel amplifiers (very easy) for a "darker voice" sound; however, you still get only 12 watts per channel when using 16 ohm speakers.
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.