eastone
pfm Member
What is the sixth board? How does it alter the circuit?
first watt f5
- Thread starter philiphifi
- Start date
What is the sixth board? How does it alter the circuit?
eastone
pfm Member
Intriguing. If nothing else it would be great to hear how the transformers are affecting the signal, as a point of comparison.
jtgofish
pfm Member
No such thing as a "boring sounding" amp or a "musically involving" amp. "Rich and smooth"?? Ah coloured then!?
Well we all hear differently.I would like a dollar for every time I have have heard a system and been able to identify a component that was detracting from its overall musicality.Usually something that had poor articulation and timing.When you replace that component the system then becomes far more musically convincing and the owner of the system has always agreed.
I tend to agree that rich and warm probably is some sort of colouration but in terms if getting overall system balance that can be useful.You can certainly overdo though.
But since I have owned a Bakoon amplifier every other amplifier I have heard sounds coloured [and crude and lacking in precision and clarity] by comparison.
davidjt
pfm Member
I'm intrigued by the fact that a 'new school' technician such as Tom Christiansen can engineer amps and pre-amps with (effectively) no distortion at all, and contrary to what we thought we wanted some of us promptly set about re-introducing it with valves or vinyl. Which presumably accounts for the Marmite reaction to ASR.
I'm also investigating a DiyAudio build and one of the things I'm still hung up on is the small details that aren't covered by the BOMs. What did you use for insulators for the TO-247 packages? When I look for mica (on Digikey for example) I only find TO-220 and T-3 form factors. If I look for TO-247 specific insulators I see many materials and thicknesses of sil-pads, aluminum oxide, etc. but no mica. What would you recommend/did you use?
I used Keratherm insulators from the diy store. I just checked and they are sold out.
I also see they are sold out of lsk170 and lsj74’s. I don’t know if you already have the input jfet’s but I would recommend you buy the jfet’s from the store as there are huge numbers of fake 2sk170 and 2sj’s for sale.
back to the insulators, when I bought mine I ended up with quite a few. I will have to search but might be able to provide you with the 4 you need for the F5.
cheers
Ian
I also see they are sold out of lsk170 and lsj74’s. I don’t know if you already have the input jfet’s but I would recommend you buy the jfet’s from the store as there are huge numbers of fake 2sk170 and 2sj’s for sale.
back to the insulators, when I bought mine I ended up with quite a few. I will have to search but might be able to provide you with the 4 you need for the F5.
cheers
Ian
philiphifi
pfm Member
hi - all the parts arrived yesterday. I had to pay £48 duty!! so bear that in mind when you order from the States. I also purchased the transformer https://www.reichelt.com/gb/en/toro...r3-Pg5wIVCsPeCh3HmA25EAEYASABEgJWt_D_BwE&&r=1. If you have built the F5 using the same parts before, could you please let me know if my connections are correct? I also want to know how to ground everything properly. Once i have built it, i will ask a pro to make sure everything is tested and do a PAT test. Many thanks (does anyone know how to upload an image ?)
philiphifi
pfm Member
i don't know really. it says duty to pay and RM asked me to pay £48 before releasing.
This is what I was going to get for the F5 (which is in stock): https://diyaudiostore.com/products/linear-systems-matched-jfets?variant=30120611840034
The MOSFETs are out of stock but are included in the F5 parts kit which is in stock.
Unfortunately I am about to travel the first 3 weeks of March and can't place my DiyAudioStore order because it would arrive while we're away. So I'm crossing my fingers that all those parts will still be available in late March!
Thanks for the offer on the insulators! I'm in Valencia so they might be expensive to post but let me know what you find!
I'm not 100% sure but I think it's these: https://diyaudiostore.com/products/linear-systems-matched-jfets?variant=30120611840034
From memory the F5 needs matched pairs of 2SK170/2SJ74 preferably BL. This was why I bought the Linear Systems matched pairs from DIYAudio as I really couldn't face the pain of trying to find 2SJ74 that were genuine and matched the few 2SK170 BL's that I have.
Cheers
Ian
davidjt
pfm Member
Jason Donald at the store is really helpful - if the warehouse can accomodate it, he'd probably let you pay now to 'book' one and despatch on receipt of an email saying you're back. Alternatively he may advise that there are plenty in stock and a slowish turnover - it's the ACA that keeps selling out.
I did actually ask about that and it was possible but it sounded like a bit of a PITA for both sides, and PayPal would charge a few extra percent in that case (don't remember why that was).
I think I'm going to take my chances and wait until after the trip. That will give me more time to read up on the different amp options, and consider whether, for example, it is with buying the back panel/heatsink mounting kit for $80 vs buying the parts myself.
In the mean time I've bought a Hakko FX888d soldering station and am trying to pick out one or more extra multimeters. I have an ok £30 one now but saw the build guide recommends having 3 cheap ones for measuring 3 things at once without moving probes (makes sense).
Then there'sother threads saying your also need a pro meter with true RMS (e.g. £150 Bryman or £350 Fluke!!).
I don't want to have a crap setup but I don't have room for used bench gear bargains, and I have a feeling I don't need a Fluke for this project.
Arkless Electronics
Trade: Amp design and repairs.
One meter should suffice! I'd be much more concerned about getting an oscilloscope and a signal generator!
davidjt
pfm Member
I didn't go for the hardware kit on cost grounds - VAT @ 20% on the (cost + carriage), plus Royal Mail's collection fee put me off. But so far deliveries to the French address have escaped completely, so in Spain who knows? Maybe you do already?
Touch wood, all my builds to date have worked first time with nothing fancy in the way of test gear. If you're using the diyAudio Universal PSU, the illustrated build guide is excellent and simple logic applies when checking your wiring. (Bear in mind that the pictures will show a different transformer from the one you have.)
As for the amp boards, follow the recommended step-by-step advice and always stop when getting tired. Having to use de-soldering braid the next morning to correct a mistake made the night before is dispiriting.
I found one of the most helpful features of the crossover and ACA build guides to be the provision of voltage check lists - not (fortunately) for trouble-shooting but simply peace of mind. Maybe I should suggest adding them to the others, or at least to future editions.
Once built, your objectivity goes out of the window of course. But you're enjoying the music too much to care about stuff like that.
Touch wood, all my builds to date have worked first time with nothing fancy in the way of test gear. If you're using the diyAudio Universal PSU, the illustrated build guide is excellent and simple logic applies when checking your wiring. (Bear in mind that the pictures will show a different transformer from the one you have.)
As for the amp boards, follow the recommended step-by-step advice and always stop when getting tired. Having to use de-soldering braid the next morning to correct a mistake made the night before is dispiriting.
I found one of the most helpful features of the crossover and ACA build guides to be the provision of voltage check lists - not (fortunately) for trouble-shooting but simply peace of mind. Maybe I should suggest adding them to the others, or at least to future editions.
Once built, your objectivity goes out of the window of course. But you're enjoying the music too much to care about stuff like that.