Many thousands on the forum started with Nelson’s full size designs and did just fine. However, build a Mini, you can finish it in the time it takes to make dinner and you will have an epic amp to listen to while you do complete the f-4 / and a linestage.
Definitely. Mini sounds great and a no-brainer. It is so cheap it is almost a stalking stuffer. It sounds like the OP has experience working on electronics just not building. I started with the F6 which has a nice completion kit and a great build guide. Easy way to get a heck of a great amp.
Hmm. I'm on the same boat.... the BA-3 gain board is out of stock. Does "Wayne's preamp" drive the voltage too?
But, as usual, I'm complicating things.... why not?
My plan now is to run TWO F4 in balanced mode... for that I need a balanced preamp, hopefully something that will do +/- 14.4V for full gain of the amp.
And I had planned on using a BA-3, but it looks single ended... so does my current CJ PV9 preamp.
Besides, I'd love to try the B1 and B1K, plus a couple of my solid state preamps (they don't swing enough voltage either).
So...
Option 1: Transformer that will take 14.4V SE to +/-14.4. That will allow me to run the SE preamps with enough swing.
Option 2: Transformer that will take 2V to 14.4V.
I figure that current should not be much of an issue since the F4 is a high impedance load so it shouldn't be an issue.
Option 3: A proper balanced preamp that will drive 14.4V SE and +/- 14.4V balanced.
Now.... before you ask... "why"... I'm currently driving a tweaked, updated CJ PV9 into a single F4 and into Audio Note AN-K ( bought them used, don't worry). The system sounds sublime... but it won't play rock! (*) And let's face it, the little speakers can rock and swing a lot more power, so if I can double the volume it would help a lot for hearing Aerosmith and Lynyrd Skynyrd.
(*) Well, it does, sort of. I suppose I need to hook up the external woofers and that will provide the kick in the solar plexus, but still 33 wpc is just not enough for a 90db speaker when the guitars are a'awailin' and the drummer is a'akickin' Oddly, btw, the system does Metallica quite well as it is.
But, as usual, I'm complicating things.... why not?
My plan now is to run TWO F4 in balanced mode... for that I need a balanced preamp, hopefully something that will do +/- 14.4V for full gain of the amp.
And I had planned on using a BA-3, but it looks single ended... so does my current CJ PV9 preamp.
Besides, I'd love to try the B1 and B1K, plus a couple of my solid state preamps (they don't swing enough voltage either).
So...
Option 1: Transformer that will take 14.4V SE to +/-14.4. That will allow me to run the SE preamps with enough swing.
Option 2: Transformer that will take 2V to 14.4V.
I figure that current should not be much of an issue since the F4 is a high impedance load so it shouldn't be an issue.
Option 3: A proper balanced preamp that will drive 14.4V SE and +/- 14.4V balanced.
Now.... before you ask... "why"... I'm currently driving a tweaked, updated CJ PV9 into a single F4 and into Audio Note AN-K ( bought them used, don't worry). The system sounds sublime... but it won't play rock! (*) And let's face it, the little speakers can rock and swing a lot more power, so if I can double the volume it would help a lot for hearing Aerosmith and Lynyrd Skynyrd.
(*) Well, it does, sort of. I suppose I need to hook up the external woofers and that will provide the kick in the solar plexus, but still 33 wpc is just not enough for a 90db speaker when the guitars are a'awailin' and the drummer is a'akickin' Oddly, btw, the system does Metallica quite well as it is.
The BA-3 is differential/push pull and designed for the exact purpose of driving the output stage of the F4. I might have an extra board. I also have original Toshiba 313/2013’s that can be sold if you send me your Ferrari
I also have a fully working Wayne’s board ready built. Won’t clip your F4 but with highish rails and an output tranny it will rock pretty good. This can be sold for the meer price of the crown jewels of the prince of Iceland.
FYI there is a balanced version of the BA3 front end that can be built basically using the existing board. You will need one board per channel.
https://www.diyaudio.com/community/threads/burning-amp-ba-3b-balanced.201281/
https://www.diyaudio.com/community/threads/burning-amp-ba-3b-balanced.201281/
Same. I have a PL XP-10 I would use to drive them. The spec sheet from Pass Labs says it has +10dB gain, but then somewhere else I read max output is 20V. Do those numbers make sense?
^
Which numbers? A pre-amp with 10dB of gain and a 20V max output makes sense to me. I do not know if those are correct though for a factory XP-10. You'll need to verify. I'm too lazy to look it up, but I'm pretty sure the XP-10 has variable gain.
On to the hypothetical example... 10dB => 3.16X voltage gain. 20Vpk => ~14vrms / 3.16 => 4.5rms => within the norms for a differential signal from a source. So, that 'makes sense' to me.
My biggest concern with the XP-10 is quantum tunneling... 😉
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If you're referring to the other... Neither the overall statement you've quoted from TonyEE nor the numbers in that statement make sense to me. The F4 has no voltage gain even when run balanced with a differential signal. However, I often misinterpret the intent behind the words... Those numbers and the overall statement could make sense with more / correct context around them.
Which numbers? A pre-amp with 10dB of gain and a 20V max output makes sense to me. I do not know if those are correct though for a factory XP-10. You'll need to verify. I'm too lazy to look it up, but I'm pretty sure the XP-10 has variable gain.
On to the hypothetical example... 10dB => 3.16X voltage gain. 20Vpk => ~14vrms / 3.16 => 4.5rms => within the norms for a differential signal from a source. So, that 'makes sense' to me.
My biggest concern with the XP-10 is quantum tunneling... 😉
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If you're referring to the other... Neither the overall statement you've quoted from TonyEE nor the numbers in that statement make sense to me. The F4 has no voltage gain even when run balanced with a differential signal. However, I often misinterpret the intent behind the words... Those numbers and the overall statement could make sense with more / correct context around them.
I came up with 14.4V from the simple rating of the F4 at 25wpc into 8 ohms. That is a 14.4V voltage. ( P = V^2 / R )
If running balanced, +/- 14.4V then that will yield indeed 100wpc into 8 ohms because the differential is 28.8V.
The amp seems to be current shy since it can't swing 50wpc into 4 ohms... At 25wpc into 8 ohms it's driving a bit over 1.76A so into 50wpc @4 ohms you'd expect 3.5A.. I believe the rating is 40wpc into 4 ohms, so that is only 3.16A.
Perhaps it needs to be extended with more devices to provide more current. In my case I'm driving 6 ohm speakers, not the 4 ohm, 83 db/w, Maggies... so I have resigned myself not to run the F4s with Maggies.. .ever... that's why I ended up buying another set of speakers.
The new speakers are 6 ohms, so that means 2.4A which is well within the current drive of the F4. They are also 90 db/w. IMHO, that's the bottom line with this amp, running single ended. I did run a pair of 6 ohm, 85 db/w speakers before and they sounded spectacular but soft. I'd say they were fine for about 75% of all music but the upgrade was good to cover up to 90% of all music, even Metallica.
To gain that Spinal Tap 11 I'd either need to bump this up to something like big corner Klipschorns or something with BIG horns. But I believe my wife would nix the idea of this:
https://www.passdiy.com/projects/images/content/kleinhorn2_2.png
Hence, the idea of running a pair of nice, efficient smallish speakers with two F4s and a balanced preamp.
Now, the preamp gain... my current tube job will swing 20V and has 31db of line stage gain... With your standard 2V level (even less) I can easily push the F4 into "current clipping"... mostly I hear a little bit of harshness in the vocals. But this is at a reasonable enough volume. That's why I want to run two F4 in balanced mode... to gain that extra 6 db
Oh... I don't know about quantum tunneling, BUT you must make sure that the LEDs are BLUE and from the same manufacturer to be sure that the amps become entagled, otherwise you risk out of phase 3rd order harmonic distortion.. for sure, do NOT use RED LEDs. OMG!
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^ The added context makes more sense. Thanks! 🙂. Love the POV. (To me) when trying to noodle through things like this, it's important to use proper units / nomenclature. I often get it wrong. I'm not pointing this out to 'show an error', but to see if this is more what you're looking for... and to show how I was confused.
"+/- 14.4V for full gain of the amp" is what threw me. With your calculations and previous posts... I think you're looking to increase the voltage swing. You're noting +/-14V ... that means Vp +14 and -14V => Vpp = 28V.
What I think you mean, and what I think is correct is... At rated power into 8ohms ... the F4 has roughly 20Vp or 40Vpp or +/-20V. That equates to 14Vrms.
The way it's noted is meaningfully different, but I hope you can understand my confusion.
If you back it out from known things about the amp... it makes sense. Rails are +/- 24V and you lose about 4V of usable "swing" to each rail due to losses / heat. This also ties to many anecdotal posts re: "you need a pre-amp that swings about 20V to drive an F4".
I have no idea just how close I am to being accurate about any of that, but it's how I think about it w/o looking anything up.
Most importantly - If you run balanced.... you're not increasing the rails. You're just running equal and opposite signals, so you double the voltage swing at the output. Instead of being able to swing 40vpp, the output can swing 80Vpp => 28Vrms.
I'll let you do the math, but you get more than 3dB gain if you double the voltage swing by running the amps balanced / differential. You had the Vrms correct, but at 4x the power output... you get ?? in power gain?
If you need to allow the amp to source (or sink.... I never get that right) more current, you can increase the Iq. Add more devices and/or more current per device.
I hope I got some of that right.... per usual, if I didn't, smarter people will come along and point it out.
Make sense?
"+/- 14.4V for full gain of the amp" is what threw me. With your calculations and previous posts... I think you're looking to increase the voltage swing. You're noting +/-14V ... that means Vp +14 and -14V => Vpp = 28V.
What I think you mean, and what I think is correct is... At rated power into 8ohms ... the F4 has roughly 20Vp or 40Vpp or +/-20V. That equates to 14Vrms.
The way it's noted is meaningfully different, but I hope you can understand my confusion.
If you back it out from known things about the amp... it makes sense. Rails are +/- 24V and you lose about 4V of usable "swing" to each rail due to losses / heat. This also ties to many anecdotal posts re: "you need a pre-amp that swings about 20V to drive an F4".
I have no idea just how close I am to being accurate about any of that, but it's how I think about it w/o looking anything up.
Most importantly - If you run balanced.... you're not increasing the rails. You're just running equal and opposite signals, so you double the voltage swing at the output. Instead of being able to swing 40vpp, the output can swing 80Vpp => 28Vrms.
I'll let you do the math, but you get more than 3dB gain if you double the voltage swing by running the amps balanced / differential. You had the Vrms correct, but at 4x the power output... you get ?? in power gain?
If you need to allow the amp to source (or sink.... I never get that right) more current, you can increase the Iq. Add more devices and/or more current per device.
I hope I got some of that right.... per usual, if I didn't, smarter people will come along and point it out.
Make sense?
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Not sure what the actual rated output into 4 Ohms is. In the F4 manual, NP states that it will do 50W into 4 Ohms. https://www.firstwatt.com/pdf/prod_f4_man.pdf
OK, Rigoletto, (*), so that's good news then. I thought I read 40 wpd into 4 ohms. Thanks for that info.
Class A, hmm.. exactly what do we need to do this? The plan is to use the mini chassis for the new one, that's also what the current one is using. I believe the builder is in touch with you over the SissySIT parts, I'm not the builder, just the instigator.
I wonder if we can get a balanced SiT amp. I got two matched pairs, so that ought to be enough IF you made the boards.
If I don't retire, I might also end up with the F5T v3. I wonder what kind of a stand I'll need to hold mono A2, SiT, F4 and F5T. That, per my count is three pairs of 5U, 400mm and one pair of 4U 400, mini. My plan it to put in some kind of a switchable AC power box, I also want it to switch the Entec MX5s on and off. Run the speakers full range.
(*) Well, you called yourself a "jester", not me. ;-)
..
Most importantly - If you run balanced.... you're not increasing the rails. You're just running equal and opposite signals, so you double the voltage swing at the output. Instead of being able to swing 40vpp, the output can swing 80Vpp => 28Vrms.
Make sense?
(1) I'm running backwards from the rated power, which at 25wpc is 14.4V. Yes, a simplification, but it is RMS so we can use the numbers without having to made a DC to AC conversion.
(2) Running the channels in a balanced mode does run off give us 28V off the reversed rails: running as + and - Vcc: One amp runs out of phase with the other, hence doubling the voltage. If you double the voltage, you quadruple the power: P = V^2 / R... means the power increased with the square of the voltage.. hence if you double the voltage, you quadruple the power. 25 wpc -> 100 wpc.
(3) It's good to hear about the 50 wpc at 4 ohms, perhaps I misread the amp's description. This means it can deliver the current. I sure hope the balanced F4s can play loud enough with these speakers ( well that will be a 6db increase... ).
(4) Beer if good, I prefer IPA nowadays.
It's not just a simplification... it's important because...
No, but close enough. You have the result correct, but not the mechanism re: how the additional voltage swing is achieved. It has nothing to do with the 'reversed rails'. The amp runs the same rails as with SE. In both scenarios the rails are 'reversed'. In both scenarios, the signal can 'hit the rails'. Maybe that's what you mean, but it's not how I read what you wrote... 🙂. Below is my simplification to ensure we're on the same page.
With SE, the speaker terminals are hooked one output and to ground. So... max voltage differential at the speaker terminals is from the 'rails' to ground. With the voltage loss of 24V to 20V ... Voltage swing is +/- 20V or 40Vpp or 14Vrms.
With the Balanced / differential signal, the speaker terminals are hooked between the outputs of the two 'channels'. No ground / OV. So... max voltage differential is from the positive signal at + 40V to its equal and opposite inverted partner -40V for a Vpp of 80V => 28vrms.
It's not just more simple ... this is important to you because... armed with that information, you need to rethink this... I don't want to assume that 14+14 => 28 is what's causing your confusion... I think you're missing the very important distinction between Vrms and Vpp, but I could be completely incorrect. If so, apologies.
Again.. gain has nothing to do with it. What I think you meant (previously mentioned) is drive the F4 to voltage clipping. If you have only +/- 14V => 28vpp ... ~10Vrms.... that ain't gonna get it done. If you buy or build a pre-amp like that... it's not going to be what you say you want.
All those voltages are incorrect... and #1 ... I admit that I still don't understand. As long as you do, awesome! I don't have to understand it. I think you're saying use a transformer solution to create the inverted signal... that's my SWAG. Anyway, now you can choose a suitable pre-amp that will output the voltages you desire to drive the F4 to clipping when desired.
What I'd do... is look for a pre-amplifier that was designed for balanced inputs and outputs (differential signaling) with roughly 6x gain (assuming your balanced source outputs roughly 5Vrms with a 0Vdb signal). The manufacturer / builder will likely ensure that it's capable of the proper voltage swing. Just tell them you want to ensure that it will output ~30Vrms from the balanced output at a distortion figure you're comfortable with. I'd say don't worry about all the +/- stuff and don't say "swings" 30V. Just my preferences, but I think you can see how it might be confusing. For SE... I'd just assume the builder/manufacturer did it properly alongside the balanced.
As an example... an XP-10 has a max voltage output of 20Vrms per this link... I have no idea if this is accurate, but I couldn't find it in the owner's manual. I was looking at it for Kevin.
https://hometheaterhifi.com/reviews/amplifier/preamplifier/pass-labs-xp-10-stereo-preamplifier/
I know that wasn't your example... but that would be one pre-amp that would not meet your criteria.
Nice! The new one ... will not only kick you in the solar plexus... it'll go full Van Damme on you! 🙂
Yes.
It's a Class A/B amp as ZM said.
🙂. And you can clean your boards with it.
I'm a fan of a variety of IPAs. Enjoy!Again... I might have a decent chunk of that wrong... and you may think in a completely different manner ... but I hope some of it is helpful.
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https://www.passlabs.com/wp-content/uploads/2020/01/xp-pre_specs_0.pdf
I think you read the specs incorrectly and at least one posted set of specs could be confusing. From what I've read once I got a sec to look things up is that the gain is variable from -73dB do +10dB. The max output is 20Vrms per link in previous post not 20V max => 20Vp. You got that correct, I just misinterpreted your post.
All the numbers can make sense with varied context.
no such kick with puny 8", be it from UK Wonderfabrik, or not
same as MF, they developed whole new physics
to kick but and gut, 8" driver ....... rare are FiFi ones capable ....... and AN certainly isn't
go build/buy bigger & better spks, or invest in active subs
that way 25W of A Class will suffice, greatly
same as MF, they developed whole new physics
to kick but and gut, 8" driver ....... rare are FiFi ones capable ....... and AN certainly isn't
go build/buy bigger & better spks, or invest in active subs
that way 25W of A Class will suffice, greatly
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I believe you read correctly. On the FirstWatt product page, the F4 is listed as 40W into 4 ohms. That's why I fessed up to not knowing for sure how much it'll generate in Class A.
https://www.firstwatt.com/prod.html