Couple of questions if someone can take the time to respond I'd be grateful!
1 - Has anyone done a listening test of this F5M against the Aleph-J? What are your thoughts? Differences?
2 - Anyone tried running the rails higher than NP's recommended 24V? As the document "art_f5_turbo.pdf" on page 5 points out, the 2SJ74/2SK170 is pushed to 32V. Has this caused a problem for anyone, and what would be a reason not to use a supply up to 30V? Perhaps NP to chime in and let us know his thoughts on why a higher rail wasn't used. Maybe the advantages just are not there. I'm looking for a bit more power, and if safe to run it to that voltage I would do it.
1 - Has anyone done a listening test of this F5M against the Aleph-J? What are your thoughts? Differences?
2 - Anyone tried running the rails higher than NP's recommended 24V? As the document "art_f5_turbo.pdf" on page 5 points out, the 2SJ74/2SK170 is pushed to 32V. Has this caused a problem for anyone, and what would be a reason not to use a supply up to 30V? Perhaps NP to chime in and let us know his thoughts on why a higher rail wasn't used. Maybe the advantages just are not there. I'm looking for a bit more power, and if safe to run it to that voltage I would do it.
Please refer to posts 974 through 980 where you participated in that discussion. I’m sure others will chime in with their thoughts.
Regarding your 2nd question…well you already know NP’s answer, it’s in the F5 turbo document you referenced. Yes, you can use a higher voltage rail up to 32V, and yes, the dissipation on the input JFET transistors is higher, and yes, a cascode circuit would safeguard them, and yes, NP has already designed that. You can also fit heatsinks on the JFET transistors themselves. The difference in power is about 1.3X’s. So you went from 25 watts to 32 watts/8 ohms which is miniscule (a measly 2dB in power) and largely imperceptible on dynamic loudspeakers. What does a ‘bit more power’ mean to you?
If you have a set of transformers already, you can try the experiment and listen for yourself. But if you don’t, I wouldn’t do a brand new build that isn’t optimized for the long run (i.e. cascoding the input Jfets) if you know what I mean. And with cascoding the input JFETS I would go for even higher voltage rails since you well…can (as NP stated in that document you referenced).
The F5m was meant to be a simpler design with interesting twists on 2nd harmonic distortion play to get one’s feet wet and in contrast to the original F5 which is more 3rd harmonic dominant but relies on a potentiometer in the input stage that can ‘set‘ the amount of 2nd harmonic where you like. But this requires a distortion analyzer which A LOT of folks do not have (and hence the birth of the F5M!). As such, I feel that the sonic impressions most people have regarding the F5 is one they haven’t optimized because they weren’t able to.
NP said it best in the F5M document uploaded to the 1st post of this thread:
Ideally, we should build an F5 and play with that pot and also build an F5M for comparison. And ideally, with the same output FETs since that has an important interplay as well (140/9140 vs 240/9240 as an example). Some have found the 140/9140 more ‘musical’ sounding.
The audio diy world is your oyster…have at it and enjoy the journey!
Best,
Anand.
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This... to me... is about the hardest question EVER to answer, but I will try.
All the usual caveats apply... different ears (my tin ear), brains, SPEAKERS, rest of gear, audio memory sucks, etc. etc. etc.
I literally have the F5m (different PSU, which to me might make a difference) and a variant of the Aleph J sitting next to each other at the moment.
F5m was built with parts directly from the kit minus the PSU.
AJ is the upcoming AJzm for the store built exactly with the parts that will be included with the kit, but at a slightly elevated bias over "stock".
F5m had been in the system since ... about two days after it was launched give or take. A month or more?
AJzm has been in the system for two days and is verified to be working "as expected".
Months and months ago, I compared the AJzm to a "stock" built Aleph J using the current boards in the store, and I could not tell them apart.
To ME the Aleph reminds me more of ZMs Babel J2 (I know you didn't ask that but...) There's just something about it that makes the vast majority of type of music I listen to (classic Rock from the 60's and 70's probably really badly digitally mastered from the early CD era and/or remastered again to keep up with the loudness wars) sound welcoming and inviting and non-stressful. Non-fatiguing seems to get used a lot. I think that's apt. I also listen to a lot of metal and grunge from the 80s and 90s. Does it shine with some of the foo foo recordings as much as other amplifiers (like the F5m), IMO? No. It has a way of 'taking the edge off'. I have a particular song I use from Alisson Krauss where if I cringe, I know something likely won't work for me. She sounds like an angel. Some may want to have ultimate fidelity... and on systems that purportedly have ultimate fidelity, I cringe. Will I talk about imaging and dynamics, no. To me, using 3 sets of speakers for comparisons in a couple systems ... that's largely room and speaker dependent.
To ME, the F5m may just be the best bang for the buck I've ever built. I think I even posted earlier that it has "no right" to sound as good as it does. It's fantastic! It has a tad more detail, and better bass control with my 4R speakers (I think). To me... somehow it pulls that off while still being non-fatiguing. I really, really like it.
Is one "better" than the other. I truly and honestly don't think so. If I needed to jam all the time with 4R speakers... I might lean F5m. I like to jam, and I like my big nasty 4R speakers. Thankfully my neighbors like my music too most of the time.
Right now... I'm only on my second cup of coffee trying not to wake up wifey, and I've got a little Van the man moving through the AJzm. Lovely, lovely stuff.
I hope that helps... again... I sit in the same room with people and disagree with what's heard / perceived... so...
Build whatever you have the itch for... that's my solution.
Edited to add - Pic... added. F5m left (4U / 500 b/c it was sitting around and I wanted to run higher dissipation). AJzm right in the new super cool PASSdiy 4U deluxe chassis from Modushop. Yes... it's dusty... I've been moving a few things around... which is pretty typical.
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Outside the editing window, but the post below I just read reminded me... I am running the AJzm from a balanced source / balanced pre-amp. I agree with Anand, to me... that's also preferred. However, I can also understand the counterpoint...
It all comes down to preference.
https://www.diyaudio.com/community/...s-builders-thread.382316/page-54#post-7652635
It all comes down to preference.
https://www.diyaudio.com/community/...s-builders-thread.382316/page-54#post-7652635
It seems that we keep circling back to the same questions..
I recently finished rebuilding the power supply for my F5m. The intent was to lower the voltage rails a little, as the amp was running pretty hot at a modest bias current. I‘m still using the same power transformer, the changes were made in the CRC section of the PS board. Power rails are now set at +/– 26V. (They were 29V earlier.)
I also installed small TO-92 heatsinks on the JFets. Resetting the bias current and DC offset was challenging due to the tight quarters inside the chassis. The current is now set at 1.54A and the chassis is comfortably warm, not at hot as before. I anticipate longer life for the semiconductors with this configuration.
I am not finished tweaking this configuration yet. I plan to re-install some extra bulk capacitance to the CRC filter, making it a CRCC. The amp sounds very good as-is, yet the soundstage doesn’t seem as wide or tall as it was earlier. Only by the slightest amount.
The goal of this exercise is to explore different operating points for the output FETs. Different Vds, different bias current. These are more important than an an extra dB of power capacity. Remember that I’m using different FETs. I want to hear how the FQA28N15 and IXTQ26P20P sound at higher bias. So it not so much about Watts, but the sound of the music that emerges from my speakers.
I recently finished rebuilding the power supply for my F5m. The intent was to lower the voltage rails a little, as the amp was running pretty hot at a modest bias current. I‘m still using the same power transformer, the changes were made in the CRC section of the PS board. Power rails are now set at +/– 26V. (They were 29V earlier.)
I also installed small TO-92 heatsinks on the JFets. Resetting the bias current and DC offset was challenging due to the tight quarters inside the chassis. The current is now set at 1.54A and the chassis is comfortably warm, not at hot as before. I anticipate longer life for the semiconductors with this configuration.
I am not finished tweaking this configuration yet. I plan to re-install some extra bulk capacitance to the CRC filter, making it a CRCC. The amp sounds very good as-is, yet the soundstage doesn’t seem as wide or tall as it was earlier. Only by the slightest amount.
The goal of this exercise is to explore different operating points for the output FETs. Different Vds, different bias current. These are more important than an an extra dB of power capacity. Remember that I’m using different FETs. I want to hear how the FQA28N15 and IXTQ26P20P sound at higher bias. So it not so much about Watts, but the sound of the music that emerges from my speakers.
I've run my BA3 at 32 volts for years. No problems. Increasing the rails was one of the first steps with F5 Turbo discussion, V1 I believe. V2 and V3 used "protection" for the Jfets....they never saw the higher voltge. Nelson advises they break down after 40 volts, which would really be pushing it. I dont know if it makes a difference, but my BA3 used toshiba jfets....
Thanks! You are correct, that discussion on the sound was had, totally lost that one. And also for the detailed response on the notes between the F5/F5M. How much is a "bit" more? Well, that 7 or 8w could do the trick so long as distortion remains as is, and there's no danger in toppling the JFETs I would be happy going with the new transformers. They're fairly marginal at 22V/400VA, the bias could be about 425mV before reaching the max for both sides. I think it will be worth a try though. Yes, and for sure the JFETs would use a heatsink, essential!Please refer to posts 974 through 980 where you participated in that discussion. I’m sure others will chime in with their thoughts.
Regarding your 2nd question…well you already know NP’s answer, it’s in the F5 turbo document you referenced. Yes, you can use a higher voltage rail up to 32V, and yes, the dissipation on the input JFET transistors is higher, and yes, a cascode circuit would safeguard them, and yes, NP has already designed that. You can also fit heatsinks on the JFET transistors themselves. The difference in power is about 1.3X’s. So you went from 25 watts to 32 watts/8 ohms which is miniscule (a measly 2dB in power) and largely imperceptible on dynamic loudspeakers. What does a ‘bit more power’ mean to you?
If you have a set of transformers already, you can try the experiment and listen for yourself. But if you don’t, I wouldn’t do a brand new build that isn’t optimized for the long run (i.e. cascoding the input Jfets) if you know what I mean. And with cascoding the input JFETS I would go for even higher voltage rails since you well…can (as NP stated in that document you referenced).
The F5m was meant to be a simpler design with interesting twists on 2nd harmonic distortion play to get one’s feet wet and in contrast to the original F5 which is more 3rd harmonic dominant but relies on a potentiometer in the input stage that can ‘set‘ the amount of 2nd harmonic where you like. But this requires a distortion analyzer which A LOT of folks do not have (and hence the birth of the F5M!). As such, I feel that the sonic impressions most people have regarding the F5 is one they haven’t optimized because they weren’t able to.
NP said it best in the F5M document uploaded to the 1st post of this thread:
Ideally, we should build an F5 and play with that pot and also build an F5M for comparison. And ideally, with the same output FETs since that has an important interplay as well (140/9140 vs 240/9240 as an example). Some have found the 140/9140 more ‘musical’ sounding.
The audio diy world is your oyster…have at it and enjoy the journey!
Best,
Anand.
These are the small TO-92 heatsinks that I used:
532-575200B00
They are not as tall as they look in the image. They clip on fairly easily, but you will want to support the JFets from underneath to avoid bending the leads. The clip mount allows them to be used on parts that are installed facing each other, as in the standard F5 boards.
532-575200B00
They are not as tall as they look in the image. They clip on fairly easily, but you will want to support the JFets from underneath to avoid bending the leads. The clip mount allows them to be used on parts that are installed facing each other, as in the standard F5 boards.
A thorough coverage of subjective expression! Given all the info, I may try the F5M as I have a good supply of 2SK170BL devices. I'm a huge AKAUS fan too, and I also have a couple of tracks of hers I use for "demo testing". A bit off topic here...another CD I can highly recommend for incredible recording engineering is Mary Chapin Carpenter's album "Come on, come on". Especially "Rhythm of the Rain" and the title track. The space in the recording studio and depth of imaging is undeniably some of the best I've heard. Especially the title track.This... to me... is about the hardest question EVER to answer, but I will try.
All the usual caveats apply... different ears (my tin ear), brains, SPEAKERS, rest of gear, audio memory sucks, etc. etc. etc.
I literally have the F5m (different PSU, which to me might make a difference) and a variant of the Aleph J sitting next to each other at the moment.
F5m was built with parts directly from the kit minus the PSU.
AJ is the upcoming AJzm for the store built exactly with the parts that will be included with the kit, but at a slightly elevated bias over "stock".
F5m had been in the system since ... about two days after it was launched give or take. A month or more?
AJzm has been in the system for two days and is verified to be working "as expected".
Months and months ago, I compared the AJzm to a "stock" built Aleph J using the current boards in the store, and I could not tell them apart.
To ME the Aleph reminds me more of ZMs Babel J2 (I know you didn't ask that but...) There's just something about it that makes the vast majority of type of music I listen to (classic Rock from the 60's and 70's probably really badly digitally mastered from the early CD era and/or remastered again to keep up with the loudness wars) sound welcoming and inviting and non-stressful. Non-fatiguing seems to get used a lot. I think that's apt. I also listen to a lot of metal and grunge from the 80s and 90s. Does it shine with some of the foo foo recordings as much as other amplifiers (like the F5m), IMO? No. It has a way of 'taking the edge off'. I have a particular song I use from Alisson Krauss where if I cringe, I know something likely won't work for me. She sounds like an angel. Some may want to have ultimate fidelity... and on systems that purportedly have ultimate fidelity, I cringe. Will I talk about imaging and dynamics, no. To me, using 3 sets of speakers for comparisons in a couple systems ... that's largely room and speaker dependent.
To ME, the F5m may just be the best bang for the buck I've ever built. I think I even posted earlier that it has "no right" to sound as good as it does. It's fantastic! It has a tad more detail, and better bass control with my 4R speakers (I think). To me... somehow it pulls that off while still being non-fatiguing. I really, really like it.
Is one "better" than the other. I truly and honestly don't think so. If I needed to jam all the time with 4R speakers... I might lean F5m. I like to jam, and I like my big nasty 4R speakers. Thankfully my neighbors like my music too most of the time.
Right now... I'm only on my second cup of coffee trying not to wake up wifey, and I've got a little Van the man moving through the AJzm. Lovely, lovely stuff.
I hope that helps... again... I sit in the same room with people and disagree with what's heard / perceived... so...
Build whatever you have the itch for... that's my solution.
Edited to add - Pic... added. F5m left (4U / 500 b/c it was sitting around and I wanted to run higher dissipation). AJzm right in the new super cool PASSdiy 4U deluxe chassis from Modushop. Yes... it's dusty... I've been moving a few things around... which is pretty typical.
What is "AJzm"? You mentioned something upcoming from the DIY store? Is this a "zen mod"? Is there a new board for this? Whatever the mod might be - so long as it doesn't detract in any way from the stock AJ design, I'd be game to try it. Right now just looking for a way to give a power bump to the AJ without risking any components, and it seems like from the responses I can do that with the heat sinks on the 2SJ74's.
Hi TA - yes, I have a bunch of these in my heat sink supply. Having used them on other projects, I recommend do NOT apply them after installation. They are difficult to get on and a high risk of folding the TO-92. I usually put the device in my bench vise with plastic jaws and gently close right below the body, use a bit of Noctua heat sink compound and push it down to fit. I like the other ones that another post mentioned on Ali Express, surprised they haven't shown up on Amazon or eBay. Thanks for the response!
Thanks!
I don't think you'd be disappointed. I never know just "how many" amps people may want to build try. I need to realize that sometimes not everyone wants to build everything they can get their hands on... and ... some people have way more self control than I.
I will check that out! I like a lot of her music, but that one escaped my attention.
Yep, as Anand said zm is for Zen Mod. A bit of a riff on the new "m" for minimalistic? that Nelson is using. ZM means zero minimalism in this context. He goes a little bit in the opposite direction with parts count sometimes on his iterations. KIDDING!
I will be in the store soon... ish...
Yes new boards.ZM would need to comment re: that. I certainly don't think it detracts from anything. Anand wrote that gorgeous review above.
Then in fairness, IMO, if you're not one of those folks that's just itchin' to build it, then you can likely achieve your goal with your existing AJ like you said. You already adore it, and it's a known entity. Opinions are like... well ya know... but if that doesn't work, then a Classic Aleph may be the ticket. I built an A60 to move air... it replaced my BA-3 as the get down and boogie amp in my rotation, and I LOVE the BA-3 too... Just somethin' about those Alephs that makes me grin.
Enjoy!
I said, you quoted: "...and it seems like from the responses I can do that with the heat sinks on the 2SJ74's." For completeness it should have said:
"and it seems like from the responses I can do that with adding heat sinks on the 2SJ74's along with increasing the supply rails to 27V"
To be clear!
"and it seems like from the responses I can do that with adding heat sinks on the 2SJ74's along with increasing the supply rails to 27V"
To be clear!
Aleph is an Aleph is an Aleph
but ZM's is most Alephish of them all
with some brain any can be set to sound how you like it, the possible difference being just power/channel
Following up on the post I made about rebuilding the power supply in my F5m:
Adding a 24,000 uF cap (Kemet ALS70 series) to each rail on the tail end of the CRC filter had a remarkable effect on the sound of my amp. The depth, breadth and height of the soundstage were all improved, as was the 3D location of instruments. So that was very worthwhile.
I have been in the habit of building dual-mono power supplies in my FW clone amps for some time. The Aleph J SS was the first with a shared supply, then the F5m as it seemed reasonable to follow the smaller and less expensive route as written by Pa. The Aleph J seems more robust to having a simple shared supply (just two sets of 80 uF motor run caps to bolster the channel power.) The F5m runs better with lots of capacitance hooked up to where the speaker returns are connected.
Adding a 24,000 uF cap (Kemet ALS70 series) to each rail on the tail end of the CRC filter had a remarkable effect on the sound of my amp. The depth, breadth and height of the soundstage were all improved, as was the 3D location of instruments. So that was very worthwhile.
I have been in the habit of building dual-mono power supplies in my FW clone amps for some time. The Aleph J SS was the first with a shared supply, then the F5m as it seemed reasonable to follow the smaller and less expensive route as written by Pa. The Aleph J seems more robust to having a simple shared supply (just two sets of 80 uF motor run caps to bolster the channel power.) The F5m runs better with lots of capacitance hooked up to where the speaker returns are connected.
Speaking (off-topic) of the Aleph J...
I have run both of mine on 26.5V power supplies. The original one with store boards has a dual-mono CRCRC fronted by Antek AS-3220 transformers. The Aleph J SS uses a shared CRC store PSU board with synchronous rectifiers and an Antek AS-4220 transformer. I tweak the front end slightly by changing the zener diode to 10V and adjusting the associated resistor to keep the current the same into the diff pair of J74. I also use a 200 Ohm resistor below the current source to drop the voltage a little further before entering the diff pair. So the JFets don't see much higher voltage than they normally would given 24V rails.
I have run both of mine on 26.5V power supplies. The original one with store boards has a dual-mono CRCRC fronted by Antek AS-3220 transformers. The Aleph J SS uses a shared CRC store PSU board with synchronous rectifiers and an Antek AS-4220 transformer. I tweak the front end slightly by changing the zener diode to 10V and adjusting the associated resistor to keep the current the same into the diff pair of J74. I also use a 200 Ohm resistor below the current source to drop the voltage a little further before entering the diff pair. So the JFets don't see much higher voltage than they normally would given 24V rails.
TA,
Sorry if you have mentioned this earlier - how much of capacitance did you have earlier in your PSU?