brommermartin
i have upgraded from coleman v4 to v7..gave me better sound and more stable regulation
so the answer must be Yes
best Bjarne
i have upgraded from coleman v4 to v7..gave me better sound and more stable regulation
so the answer must be Yes
best Bjarne
I would be interested to hear from Rod himself. I have the V5 in my 4P1L and got the V7 boards when building my 6A3 amp so i had the option of upgrading the 4P1L and didn't bother. From looking at the manuals it just looked like a revision of the PCB layout.
The V5 and the V7 are almost identical circuits, so no need to upgrade any of those.
But the V7 is a big change from the V4, and represents a best effort to improve the sound - mainly by presenting higher impedance (looking out of the filament), and flat impedance up to 20kHz.
But the V7 is a big change from the V4, and represents a best effort to improve the sound - mainly by presenting higher impedance (looking out of the filament), and flat impedance up to 20kHz.
And -as my measurings shows- V7's PSRR is about 20dB better than V4's in the whole 10Hz-100kHz band (except 200-300Hz region).
O, yes! I nearly forgot about the upgrade to the input-voltage noise rejection! Thanks, Bela.
Hello fellow 4p1l-ians!
I just read about the new Lampizator Atlantic DAC which uses the 4p1l as output tubes. How the hell (pardon my French) does Mr. Fikuz manage to get them quiet enough for source use, and in one cabinet only I might add? Here we go about building separate power supplies, shields and all kinds of stuff to get our lineamps noise free but it seems that it's not really necessery. Has anybody had any luck with building DHT preamps in one chassis or does Lampizator use some kind of magic to get it done?
I just read about the new Lampizator Atlantic DAC which uses the 4p1l as output tubes. How the hell (pardon my French) does Mr. Fikuz manage to get them quiet enough for source use, and in one cabinet only I might add? Here we go about building separate power supplies, shields and all kinds of stuff to get our lineamps noise free but it seems that it's not really necessery. Has anybody had any luck with building DHT preamps in one chassis or does Lampizator use some kind of magic to get it done?
Hard to say from his pictures what kind of load the 4p1l presents.
I found that step down transformer is considerably reducing the microphonic effect.
As you can few posts away, I've successfully built a line stage in the same enclosure and it is quiet and barely any microphonics.
Cheers,
Radu
I found that step down transformer is considerably reducing the microphonic effect.
As you can few posts away, I've successfully built a line stage in the same enclosure and it is quiet and barely any microphonics.
Cheers,
Radu
I've run 4P1L line stages for years with 2v input from a ES9023 DAC. Solid chassis with wood sides, and 4mm aluminium top plate. I go for solid - thin metal doesn't do it and can ring. The chassis should be inert. Given that, I've never had much of an issue and didn't need rubber dampers or suspended sub-chassis.
Has anybody had any luck with building DHT preamps in one chassis :
vbenonisen:
Attached pics of a 10 dht pre/linestage. Made with Irons from Tribute (Bless him, Opt's and the hv power and chokes)
Gain is 2x volume set at max open.
Noise at outputs max volume is 110 microvolt
Vibration damping ala Th Mayer ( guessed based on pics from his website)
and of course: Rod's excellent filamentregulators
vbenonisen:
Attached pics of a 10 dht pre/linestage. Made with Irons from Tribute (Bless him, Opt's and the hv power and chokes)
Gain is 2x volume set at max open.
Noise at outputs max volume is 110 microvolt
Vibration damping ala Th Mayer ( guessed based on pics from his website)
and of course: Rod's excellent filamentregulators
Attachments
Last edited:
Very nice Vegard. Veeery nice. I wasn't aware of that your amp was a one chassis affair. 10 is a bit to rich for my income, but I will definitely try to make a DHT preamp in one box. My old 26 preamp was in 3 boxes, but I've decided to downscale. What is the main problems I will be facing? Is it the magnetic fields from the filament supplies?
Thanks. Have edited my post as I forgot to mention Rod's excellent regulators.
Suggest you have a look at Ale's site. Several very well documented and (asumed)
excellent sounding linestages there
Suggest you have a look at Ale's site. Several very well documented and (asumed)
excellent sounding linestages there
Yes Ale's site is indeed excellent. But my impression is that he always uses separate power supplies. What I need is probably some kind of theory on best component placement in "restricted areas" (read: crammed boxes).
Layout the preamp to keep the input wiring (grid and ground) very short, and similarly with the output. Locate the tube and the input & output connectors at the opposite end of the chassis to the transformers. Don't run any signal wiring right across the chassis. Route grid-wire twisted with the ground wire, and same for output.
Ale's gyrator board should be good for low-EM-coupling.
In a crammed chassis. keep the trafo->rectifier->cap wiring as short as can be: every 10mm you can reduce it will help. In a single chassis, I would probably use Cree SiC rectifier diodes for B+ ... valve-rectifiers may add to the problems. Use choke-input for the B+, and maybe even for the Filament (Hammond 159ZC, for example). I prefer chokes/trafos under the chassis top-plate, to reduce coupling to the tube.
The Power transformers & chokes should be at least 150-200mm from the tube & wiring, or I suspect there will be some coupling.
Ale's gyrator board should be good for low-EM-coupling.
In a crammed chassis. keep the trafo->rectifier->cap wiring as short as can be: every 10mm you can reduce it will help. In a single chassis, I would probably use Cree SiC rectifier diodes for B+ ... valve-rectifiers may add to the problems. Use choke-input for the B+, and maybe even for the Filament (Hammond 159ZC, for example). I prefer chokes/trafos under the chassis top-plate, to reduce coupling to the tube.
The Power transformers & chokes should be at least 150-200mm from the tube & wiring, or I suspect there will be some coupling.
Absolutely agree with Rod, which is hardly surprising since he has the right answers here. I'm familiar with Ale's builds - he comes over at times and we listen to a bunch of DHT gear. His Gen 2 01A preamp is really special. He and I like to use outboard PSU and filament supplies. For all the reasons Rod mentions - keep the magnetic components away from the tubes. But also for ease of experimenting.
I now use a lot of small chassis. Light and easy to move around, which you do a lot to change components. No boat anchors. So I have separate boxes for the output stage, line stage, PSU, each filament supply. I have some average PSUs, and some ridiculous overkill PSUs with AZ1 mesh rectifiers, two enormous chokes and so on. Yes, overkill sounds slightly but audibly better and whether it's cost-effective is a personal decision.
When it comes to filament supply I think overkill is the only way for filament bias. Choke input sounds better, and audibly better. I use the 159ZC chokes Rod mentions, and also a bunch of huge 280mH chokes rated 2.5 amps, 3.5 RDC. They sound even better. Magz goes LCLC even. Thomas Mayer uses chokes. So I would say take the filament supply outboard and don't be happy with anything less than choke input - bigger the choke the better.
I'm currently building an 01A preamp for somebody and having put it all in a single chassis without choke input I've given up and I'm going to split it into 2 chassis. Yes it should be possible to build in one chassis but I've never felt good about it yet.
I now use a lot of small chassis. Light and easy to move around, which you do a lot to change components. No boat anchors. So I have separate boxes for the output stage, line stage, PSU, each filament supply. I have some average PSUs, and some ridiculous overkill PSUs with AZ1 mesh rectifiers, two enormous chokes and so on. Yes, overkill sounds slightly but audibly better and whether it's cost-effective is a personal decision.
When it comes to filament supply I think overkill is the only way for filament bias. Choke input sounds better, and audibly better. I use the 159ZC chokes Rod mentions, and also a bunch of huge 280mH chokes rated 2.5 amps, 3.5 RDC. They sound even better. Magz goes LCLC even. Thomas Mayer uses chokes. So I would say take the filament supply outboard and don't be happy with anything less than choke input - bigger the choke the better.
I'm currently building an 01A preamp for somebody and having put it all in a single chassis without choke input I've given up and I'm going to split it into 2 chassis. Yes it should be possible to build in one chassis but I've never felt good about it yet.
Thank you Mr. Coleman. I will save your reply and study it very carefully. I probably start with 2p29l just for fun and use it with Ale's gyrator boards. Has anybody listened to this tube in preamp duty?
My thoughts exactly - but this time I will do it anyway. The transformer quality probably matters a lot. I've read that Hammond transformers have huge hum fields so maybe this is the time for some investments in Weiss and Lundahl from Thomas Mayer.
This might also help to improve:
http://www.diyaudio.com/forums/powe...sformer-snubber-using-quasimodo-test-jig.html
http://www.diyaudio.com/forums/powe...sformer-snubber-using-quasimodo-test-jig.html
A bit too complex build for an amateur like me I'm afraid. But I will look into snubbers and such. Thank you.
Hey, Andy
What power transformer do you use for the filament supply? Being choke input you would need more volts than Rod C specifies in his (very useful) app notes. I'm planning something similar and I'm guessing it needs to be about 20VAC.
Thanks.