Wanted - First Watt F5 good DIY build

[lordmortlock]

I’d like to try a well built F5 power amp in my system as an alternative to valves. Does anyone have one that they’d like to sell please?

Thanks, jake

[montesquieu]

I have one of these on the way for the study ... 20w seemingly based on a Pass Alpeh circuit. The Valab stuff is invariably good quality. I intend to post findings.

It's taking an extra couple of weeks to arrive at they had to install 240v mains transformers to replace the 220v ones it comes with.

I wondered after I placed the order (another case of buy first, research later :scratch: I do this too often) whether it's quite kosher - it could be exploiting Pass IP ... but too late now it's on its way.


https://www.ebay.co.uk/itm/LP-Audio-0-L1-Class-A-20W-Solid-State-Power-Amplifier-Forget-300B-SE/222735396465?hash=item33dc106e71:g:ipEAAOSwB09YG6R 0

[lordmortlock]

Look forward to the write up Tom! Looks like a neat little unit.

[Clive]

I'm very interested to know how this works out too.

[Mike S]

And me!

[Lawrence001]

+1

[lordmortlock]

Don’t let Jerry see this. He HATES the Aleph 3!

Whilst we’re on the topic of Chinese ‘clones’ ... this is on my watch list.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F 122013374050

[Lawrence001]

I have one of these on the way for the study ... 20w seemingly based on a Pass Alpeh circuit. The Valab stuff is invariably good quality. I intend to post findings.

It's taking an extra couple of weeks to arrive at they had to install 240v mains transformers to replace the 220v ones it comes with.

I wondered after I placed the order (another case of buy first, research later :scratch: I do this too often) whether it's quite kosher - it could be exploiting Pass IP ... but too late now it's on its way.


https://www.ebay.co.uk/itm/LP-Audio-0-L1-Class-A-20W-Solid-State-Power-Amplifier-Forget-300B-SE/222735396465?hash=item33dc106e71:g:ipEAAOSwB09YG6R 0

Did they agree to make 240v transformers, I'm surprised they didn't fob you off by saying 220v makes no difference?

[montesquieu]

Did they agree to make 240v transformers, I'm surprised they didn't fob you off by saying 220v makes no difference?

I've dealt with Kevin at Valab in Taiwan before quite a few times both for bits and pieces and for full components. The last big item I bought was a DHT preamp which I asked to be 240v, and as with this new item, it was modified for UK voltage before shipping. When testing it out for me, Graeme 'Valvebloke' said it was spot on for 240v operation and he said he was quite impressed with how it was done.

And yes, Kevin did get his supplier to make 240v transformers which he then fitted and tested before shipping out, he said his transformer suppliers were familiar with the procedure as he had just done the same for a regular customer in Australia. At no extra charge incidentally. Genunely impressive. As I say this is Taiwan we are talking about not China, the business aproach is far more like you get in Japan than on the Chinese mainland.

Just checked the tracking btw I think it's in the UK but not through customs yet, not sure what my chances are for getting it this week.

[Firebottle]

Looks rather good Tom, dual mono to boot :)

https://img.alicdn.com/imgextra/i4/101631887/TB21sQbaX_AQeBjSZFBXXX22XXa_!!101631887.jpg

[Lawrence001]

I've dealt with Kevin at Valab in Taiwan before quite a few times both for bits and pieces and for full components. The last big item I bought was a DHT preamp which I asked to be 240v, and as with this new item, it was modified for UK voltage before shipping. When testing it out for me, Graeme 'Valvebloke' said it was spot on for 240v operation and he said he was quite impressed with how it was done.

And yes, Kevin did get his supplier to make 240v transformers which he then fitted and tested before shipping out, he said his transformer suppliers were familiar with the procedure as he had just done the same for a regular customer in Australia. At no extra charge incidentally. Genunely impressive. As I say this is Taiwan we are talking about not China, the business aproach is far more like you get in Japan than on the Chinese mainland.

Just checked the tracking btw I think it's in the UK but not through customs yet, not sure what my chances are for getting it this week.

That's impressive service, is Kevin the seller of the item you sent the link to, I assumed it was a Chinese seller?

[lordmortlock]

If it’s tortoise66 or something like that it’s Valab. I agree with Tom, really good service.

[Lawrence001]

I've dealt with Kevin at Valab in Taiwan before quite a few times both for bits and pieces and for full components. The last big item I bought was a DHT preamp which I asked to be 240v, and as with this new item, it was modified for UK voltage before shipping. When testing it out for me, Graeme 'Valvebloke' said it was spot on for 240v operation and he said he was quite impressed with how it was done.

And yes, Kevin did get his supplier to make 240v transformers which he then fitted and tested before shipping out, he said his transformer suppliers were familiar with the procedure as he had just done the same for a regular customer in Australia. At no extra charge incidentally. Genunely impressive. As I say this is Taiwan we are talking about not China, the business aproach is far more like you get in Japan than on the Chinese mainland.

Just checked the tracking btw I think it's in the UK but not through customs yet, not sure what my chances are for getting it this week.

Excellent service, is Kevin the seller of that item on ebay then? We could support him with purchases if his customer service is that good.

[disarmamant]

I bought some anode loading plate chokes from Kevin when he first started on E-bay. They made it to the UK, but Parcelfarce managed to deliver them to someone else and they never arrived at my address.

Kevin made me another pair for no cost as replacement. Very good service.


Sent from my iPad using Tapatalk

[Clive]

The Valab version doesn't look like an exact copy of the Aleph J unless I've not caught up with later versions. The original 2005 version has an input impedance of 242k whereas the Valab one is around 22k. There are a number of other differences but some may be more down to how the circuits are drawn out on ebay vs the Pass circuit shown on diyaudio. I'd prefer an input impedance more like the original 242k but maybe there's a good reason for it being 22k on the Valab...maybe related to the volume control (which isn't shown on the ebay circuit).

Just casually musing.....

Oh I now see it's based on the Aleph-M not J. Even so it's still breathed on by Valab, which may well be a good thing in terms of making a reliable product.

[montesquieu]

The Valab version doesn't look like an exact copy of the Aleph J unless I've not caught up with later versions. The original 2005 version has an input impedance of 242k whereas the Valab one is around 22k. There are a number of other differences but some may be more down to how the circuits are drawn out on ebay vs the Pass circuit shown on diyaudio. I'd prefer an input impedance more like the original 242k but maybe there's a good reason for it being 22k on the Valab...maybe related to the volume control (which isn't shown on the ebay circuit).

Just casually musing.....

Oh I now see it's based on the Aleph-M not J. Even so it's still breathed on by Valab, which may well be a good thing in terms of making a reliable product.

I couldn't find out much about the Aleph-M design, well not that I could follow anyway (tech-speak buried in DIY threads). What I did see suggests that although it's single ended, damping factor is still healthy (around 150 - lowish for solid state but fine in the valve world) so it may well be a possible bet for Tannoys.

Incidentally I did hear a factory Pass Labs F5 with my 12in HPDs .. although it's push-pull, it didn't have the welly to get the low frequencies really running, I bet it would be nice with Golds though. Other than that I liked it. I'd say it's a fine amp but needs careful choice of speaker.

The Valab will be driving Tannoy DC6 bookshelf dual concentrics, I'm betting it will be a lovely combination. I wouldn't expect it to drive the HPDs in the main system terribly well but I will of course give it a go, you never know till you try something. I'll be running it in the study with a Pass DCB1 so I might have the pot on the front bypassed anyway as it won't be needed ... I'm not expecting any impedance nasties though, the DCB1 should be fine even with 22k. Will also be giving it a try with the Tannoy Eatons (10in dual concentric, HPD295a but in many details, more like a Gold than an HPD).

(Edit and apologies to Jake for the thread drift this isn't really helping him find one except through regular bumpage!)

[hornucopia]

The F amps, I think, were initially designed for full range speakers, if I remember all the stuff about them on 6 Moons (which is why I got my F3 for the Ocellias) Perhaps that's why the rather more complex load of a Tannoy doesn't quite make it? They are pretty low wattage.

[Bksabath]

I have a F5 quite different from the Vanilla version :D it has been in service for the past 10 years whit not a single problem and would never go back to anyting else, unless I win the lottery and spend mega bucks that is

I can help you to build one or to source the components.

PM and we take it from there

[anubisgrau]

though aleph series were considered to be predecessors to FW, technically speaking this ain't first watt - although there are similarities with some of the FW units. if i understand correctly aleph M should stand for aleph mini so if you seek for more technical data, it should be related to mini.

i would be curious to know the final price when it arrives - custom duties, EMS plus unit price. i have a highly improved F5 unit (possibly pushed to the real limits of the circuit without any cuts) here with me which is a tad over 500 pounds.

[Bksabath]

[QUOTE=

i have a highly improved F5 unit (possibly pushed to the real limits of the circuit without any cuts) here with me which is a tad over 500 pounds.[/QUOTE]

Please define highly improved and real limit of the circuit.
There are so many variation possible from pair of transistors used, balanced and not, turbo and not, psu used for voltage and capacitance.

I have 2 pairs biased at 2.6 A driving a pair of Polk LSi15 on 24 volts rails whit 150K uF on each rail on CRCLC the Polk are a pretty hard load to drive whit nominal impedence of 4 Homs and 87dB
I am quite happy volume wise (neighbours no so much so) to push it up to 8 volts but is quite capable to go to 22 V before clipping and the chassis is ready to take a second board and go balanced
Yes vanilla version may cost about £500 to build I do not see a limit to what can be done whit it

[montesquieu]

Is there no penalty for driving these chips hard? Otherwise why run them gently at all, as in the original?

[Bksabath]

There is a common opinion that 1.3 A bias is the ideal for sound quality whit the stock mosfets or about 25 W dissipation on each so the stock / Vanilla version runs at 18 V 1.3 A

Whitout cascading the maximum voltage for the inputs Jfet is at around 30 Volts and as the mosfets are voltage driven it is quite easy to drive several of them in parallel the limiting factors became the size of the heath sink and the quality of the coupling and as one push the output voltage the propensity of the amplifier to go in to current clipping, that is much worst than voltage clipping.
Then one must consider that if the Mosfets break down they became closed circuit, so one end up whit the full rail voltage at the output, broken speakers and GF telling you I told you so:D
I have the NTE7100 speaker protection on mine whit amplimo relays it all ads up to the cost
I would certainly like to ear mine's whit a pair of Tannoy instead of the Polk IMO if you have Tannoy the vanilla version should be plenty

[montesquieu]

if you have Tannoy the vanilla version should be plenty


Was pleasant enough but not enough to really get the bottom octave sounding properly compared to my 100w Radford STA100 or even the 35w STA25 I'm running while this gets restored.

Tannoy HPDs have a fairly complex crossover and also braced cones that need a lot more control than the earlier Gold series. It wasn't a good match.

[montesquieu]

For those interested I've just posted a mini review of the incoming power amp http://theartofsound.net/forum/showthread.php?56085-Interesting-LP-Audio-20w-single-ended-Class-A-amp-from-Valab&p=935654#post935654

[disarmamant]

I’d like to try a well built F5 power amp in my system as an alternative to valves. Does anyone have one that they’d like to sell please?

Thanks, jake

Jake - If you are still looking this one looks good over on PFM

http://www.pinkfishmedia.net/forum/threads/nelson-pass-f5turbo-class-a-50w-per-channel.211059/

[lordmortlock]

Thanks Martin, thanks for looking out for me. It’s looks very well built but a fair bit more than I was expecting to pay for a diy unit.

[Brumjam]

Thanks Martin, thanks for looking out for me. It’s looks very well built but a fair bit more than I was expecting to pay for a diy unit.

Indeed. The parts cost (including the case) should be approx £500 - £700, maybe a bit more if boutique components have been used, but these amps sound great using the std BoM.

[anubisgrau]

1750 may be just about the right price, if not too expensive, for a used stock version.

there used to be a US builder who was selling FW amps at diyaudio.com forum. long time ago, i would say 10 years since he was massively loathed there. he was able to cut down costs on irrelevant parts (chasis) so was affordable, say $500. i used to have his F3 and it sounded as good as it gets. can't remember the name though, they appear from time to time.

i would certainly extend the search to aleph series of sufficient power. F5 is hyped but in reality, sound-wise, not any better than alephs so a synergy with speakers may be more important.

[hifinutt]

Indeed. The parts cost (including the case) should be approx £500 - £700, maybe a bit more if boutique components have been used, but these amps sound great using the std BoM.

yes i was thinking that about that amp
winters audio have a f1 if you get stuck

[lordmortlock]

1750 may be just about the right price, if not too expensive, for a used stock version.

there used to be a US builder who was selling FW amps at diyaudio.com forum. long time ago, i would say 10 years since he was massively loathed there. he was able to cut down costs on irrelevant parts (chasis) so was affordable, say $500. i used to have his F3 and it sounded as good as it gets. can't remember the name though, they appear from time to time.

i would certainly extend the search to aleph series of sufficient power. F5 is hyped but in reality, sound-wise, not any better than alephs so a synergy with speakers may be more important.

Tim Rawson iirc Gordan ... I remember reading about his amps. The thrust seemed to be that the diy community had an issue with him profiteering from the pass schematic that had been released for the benefit of self builders

[montesquieu]

Tim Rawson iirc Gordan ... I remember reading about his amps. The thrust seemed to be that the diy community had an issue with him profiting from the pass schematic that had been released for the benefit of self builders

Doesn't sound like he was profiteering to me. $500?

But it can be pretty unpleasant over there.

[Bksabath]

For what I know the Rawson where made whit same serious cost cutting cheap transformers and so on
The big fuss about it was that Nelson Pass give the design and help the community for free, is only reward was to get people like me to give it a go, to have some one to make dozens of amplifiers to sale and make a living out of it, not getting in the cheap and nasty components, is baaaaaaaaaaad.

If I was ever to sell my F5 or build one for a friend I would first ask Nelson permission.

He is such a nice bloke believe me, and that is why, the like of Mr Rawson had an hard time.

One thing is for sure Diyaudio is really unpleasant at times...

Why not go there any way and have a look at the Build guide they also have transistor kits and PCB all one need is a soldering Iron a Drill and couple of Multymeters to build one

[anubisgrau]

For what I know the Rawson where made whit same serious cost cutting cheap transformers and so on
The big fuss about it was that Nelson Pass give the design and help the community for free, is only reward was to get people like me to give it a go, to have some one to make dozens of amplifiers to sale and make a living out of it, not getting in the cheap and nasty components, is baaaaaaaaaaad.

If I was ever to sell my F5 or build one for a friend I would first ask Nelson permission.

He is such a nice bloke believe me, and that is why, the like of Mr Rawson had an hard time.

One thing is for sure Diyaudio is really unpleasant at times...

Why not go there any way and have a look at the Build guide they also have transistor kits and PCB all one need is a soldering Iron a Drill and couple of Multymeters to build one

When I bought F3 direct from Tim Rawson I wasn't aware of the issue, neither I knew he's making a bit of living on it. But his margin is small, super-small, say 5-10% tops, if. I was actually caught once in a longer discussion with him where he explained that building amps is a kind of a therapy for him. I didn't want to go deeper but I understood his point.

However the forum rant against him was an amazing pile of shi*te of ultimate level - it's a forum where for example Peter Daniel who knocked down a few amazing commercial products - much more innovative and ground breaking than anything NP ever did - like Shigaraki transport, Gaincard amp etc, selling copies or his versions for living with a hefty profit is revered as god. And Tim Rawson is criminal

The story about cheap and dangerous parts, repeated here, at least in the case of my F3 is a total bullshit that DIY-ers invented to ruin his work - my amp had Plitron trafo who was 100% similar to the one that NP uses in his stock F3, same boards, same Panasonic caps in filtration. If he did cuts, it was on chasis and coolers, which he cut himself from big pieces of metal, didn't anodize alu front and top plates etc - it was functional but bare ugly, you could see where his saw went.

DIY community is really not high on moral standards and the campaign was actually led by the people who had their own business via forum. Only later their motivation became obvious but it was too late for Tim. He was too cheap.

Frankly I haven't seen his amps for a long time for sale since he retreated after that storm. I am sure the owners keep them, the guy whom I passed on mine regularly calls me once per year to tell me the amp is still playing as on the first day and to thank me for selling it.

I'm sure Tim would build an amp as per request, only I have no idea how to find his contact nowadays.

[anubisgrau]

It seems the units appear for sale though seldom, like once per year or so. The last one, F5 for $400

http://www.usaudiomart.com/details/649349709-tim-rawson-amp/

[sjs]

I have one of the DiyAudio Pass VFET kits :), but at the moment it's somewhere down my very long "to do" list, so unfortunately it's not built :(