Yes. My mistake. I sometimes forget that to AJ has two pairs unlike many of the FW amps. It still had no problems with the above speakers, which are pretty average for modern multiways. They 3.5 ways.
The current store offering has two each current source and two gain devices.
The confusion is likely just terminology.
Aleph J (2 PCBs included, which makes 2 channels) - Circuit Boards,
The confusion is likely just terminology.
Aleph J (2 PCBs included, which makes 2 channels) - Circuit Boards,
So, to summarize: +- 2.5A (peak to peak) into 6 ohms will result in 18.75W. This is only 1.3 dB less than the rated 25W into 8 ohms, so nothing to worry about yet but nevertheless it seems that lower impedances are less suited. (Of course it depends on where the impedance minimum is located, in my case it's in the lower midrange where most of the “action“ is.)
Looks like my Aleph J and my Core 2-ways should play nice once I get them both built.
An externally hosted image should be here but it was not working when we last tested it.
. 🙂
Ill be using Zu Essence Mk1.B speakers with mine once I finish it up, and get it biased right. I need to finish the power connections, and make a wire harness for the switch circuit, very close now.
These speakers sound fine with the ACA, and 25-35 watt PP tube amps I have used with them so far.
These speakers sound fine with the ACA, and 25-35 watt PP tube amps I have used with them so far.
I'm a little late to the game and still learning (reading every day), so bear with me...
This summer I'm building an aleph j using boards from the diyaudio store.
I'm tempted to buy a pair of ohm Walsh 4 or 4xo but only if the aleph j will match.
From the ohm Walsh website:
The 4 says 6 ohm (good), 89 db (OK?), and 40w - 150w recommended amp.
The 4xo says 6 ohm (good), 90 db (OK?), and 50w - 200w recommended amp.
I'm most concerned about the power figures - the aleph j is far below those requirements. I'm used to speakers specified in power handling, which always seems bogus to me.
This summer I'm building an aleph j using boards from the diyaudio store.
I'm tempted to buy a pair of ohm Walsh 4 or 4xo but only if the aleph j will match.
From the ohm Walsh website:
The 4 says 6 ohm (good), 89 db (OK?), and 40w - 150w recommended amp.
The 4xo says 6 ohm (good), 90 db (OK?), and 50w - 200w recommended amp.
I'm most concerned about the power figures - the aleph j is far below those requirements. I'm used to speakers specified in power handling, which always seems bogus to me.
Depends on how loud you want to listen: 25 watts into 90 dB / 1 m ~ 104 dB / 1 m. Which is a lot. In practice you might have slightly less as the Alelph J doesn't have a lot of current if I remember correctly but you should be able to get 15-20 watts into 6 ohm so say around 100-103 dB / 1 m.
100 dB / 1 m is a lot, for me it would be enough by far =)
EDIT: As this is DIY it might be possible for you to lower the rail voltage on the Aleph J and crank up the current to give you full 25W into 6 ohm. It would probably mean modifying the circuit though.
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You should be fine. I currently am using NHT 2.5i speakers of nominal 6 ohm and 86db and they play as loud as I could ever want.
I have run 4XO's with a 2A3 based 3.5 watt amp and enjoyed the music very much, even leaned into a 1/2W SET presentation on them and enjoyed it too🙂. It kinda depends on how much volume and what type of music...it always depends on these things... and your expectations!
I found I had to add a JFET BOZ to get my Aleph J for it to sound right with my 4 Ohm, 90dB/W KEF 104/2s. That extra gain helped make them sing. There is always a way to make things work out...
If you have heard the Ohm Walsh 4XO's and like their sound I would not redirect you from the Aleph J as a match.
You can always build a second and make them into mono blocks if you need to double the power!
The Aleph J is one sweet amp!
I found I had to add a JFET BOZ to get my Aleph J for it to sound right with my 4 Ohm, 90dB/W KEF 104/2s. That extra gain helped make them sing. There is always a way to make things work out...
If you have heard the Ohm Walsh 4XO's and like their sound I would not redirect you from the Aleph J as a match.
You can always build a second and make them into mono blocks if you need to double the power!
The Aleph J is one sweet amp!
Picked up the 4xo's and like them a lot so far. When the aleph build is done, I can only hope I don't have to choose between them
Don't worry. You won't miss anything. 😉
Interesting. I did think about that same idea recently. Could you or someone else
share some more details? What about running the AJ with +/- 20 V rails?
😕
It will not be as good as 'normal' 24V rails into 4 or 6 ohm.
That said, the normal 18+18V transformer will usually load down to 22V rails anyway.
That said, the normal 18+18V transformer will usually load down to 22V rails anyway.
It will probably work, I ran mine on 22V. If you want to tweak to get more power into lower ohm then as 6L6 says the magic isn't in reducing voltage but in increasing current. Reducing voltage is just practical to do as if you just push up the current you increase dissipation.
If that isn't a problem then you could probably get away with just adding more output devices, it could double up as a heater in the winter =)
Addition: Just reducing voltage will result in more distortion too. In the end the difference between 13W and 25W into 4 ohm is ~ 3 dB which in the grand scheme of things isn't much. If 3 dB makes a huge difference for you then the Aleph J might not be the amp for you anyway so it's probably easiest to just build the default version first as you should have enough power anyway even into 4 ohm. The distortion performance of a lower voltage -> higher current into 4 ohm should be about the same as the stock one, the stock one just has less total watt capability into 4 ohm.
If that isn't a problem then you could probably get away with just adding more output devices, it could double up as a heater in the winter =)
Addition: Just reducing voltage will result in more distortion too. In the end the difference between 13W and 25W into 4 ohm is ~ 3 dB which in the grand scheme of things isn't much. If 3 dB makes a huge difference for you then the Aleph J might not be the amp for you anyway so it's probably easiest to just build the default version first as you should have enough power anyway even into 4 ohm. The distortion performance of a lower voltage -> higher current into 4 ohm should be about the same as the stock one, the stock one just has less total watt capability into 4 ohm.
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Thanks dudes. 😉
Not an issue at all. My speakers are in the 92 - 94 dB range and 8 Ohms nominally.
DC resistance of the mid-bass is about 5.8 Ohms.
That's what it's running at currently. Trannie is 500 VA per channel.
I'm going to further improve ventilation giving the headroom for quite a bit
more current. I can put my fingers on the heatsinks for some seconds. Do
you think about 60° C will still be fine? Guess I won't want to touch them
for longer than a second then.
I remember some time ago Nelson said increasing current is a key factor
for AJ sound quality.
Not an issue at all. My speakers are in the 92 - 94 dB range and 8 Ohms nominally.
DC resistance of the mid-bass is about 5.8 Ohms.
That's what it's running at currently. Trannie is 500 VA per channel.
I'm going to further improve ventilation giving the headroom for quite a bit
more current. I can put my fingers on the heatsinks for some seconds. Do
you think about 60° C will still be fine? Guess I won't want to touch them
for longer than a second then.
I remember some time ago Nelson said increasing current is a key factor
for AJ sound quality.
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