Andy, have you seen this Swiss company's approach with modular amps?
http://www.swissonor.ch/pdf/AMSys_e.pdf
http://www.swissonor.ch/pdf/Swissonor_LP311_S.18-21en.pdf
Steve
http://www.swissonor.ch/pdf/AMSys_e.pdf
http://www.swissonor.ch/pdf/Swissonor_LP311_S.18-21en.pdf
Steve
This is how I've done it using machined top plates. One for input connectors and RC regulators, second plate for 4P1L valves and third plate for the output transformers and speaker binding posts.
4P1L PSE project started – Bartola(R) Valves
4P1L PSE project started – Bartola(R) Valves
Thanks so much for your reply Ale! I'd love to see more photos of the undersides of these modular amps and preamps.
Steve
Steve
Hi Andy.
Are there any drawbacks running the 4P1L PSE in serie on the filament. I have build a test setup, and it consumes a lot less heat, compared to wiring in parallel. Are you running them in serie on your latest build ???
I have roughly the same measurements as you have on the listed schematic.
Thanks Michael.
Hi Michael
I've been running them in series filament for over 1 year and they are just fine. I had a limitation on my raw power supply so I have a 32.5R filament bias to produce 21V bias (instead of 28V) and the rod coleman regulator is set to 650mA. Absolutely no problem.
Filament series allows for a smaller filament current but you increase the filament resistor value. This impacts a tad the reflected anode impedance which is Rfil * (mu+1). The bass response of this amp is fantastic, so not detrimental at all.
Cheers
Ale
I've been running them in series filament for over 1 year and they are just fine. I had a limitation on my raw power supply so I have a 32.5R filament bias to produce 21V bias (instead of 28V) and the rod coleman regulator is set to 650mA. Absolutely no problem.
Filament series allows for a smaller filament current but you increase the filament resistor value. This impacts a tad the reflected anode impedance which is Rfil * (mu+1). The bass response of this amp is fantastic, so not detrimental at all.
Cheers
Ale
Hi Ale.
How much voltage do you put into Rods Regulator. Is it about 25volt DC ??? Need to get some more parts, but I have decided to give it a try.
Thanks Michael.
Here we go!!!!!!!!!!!!!
I am taking the 4P1L plunge. It's been a few years since I built a power amp for myself so I have an itch that needs scratching.
I got Pete's A2 driver board which I will use to directly couple to the output stage. I am certainly going single ended but I have 3k:8 output iron, I should parallel two 4P1L's for this load correct?
Now for the voltage amp section...........I read these are easy to drive no? How much drive signal do I need? The voltage amp will be a common cathode triode with a CCS anode load. Can I get away with a 6SN7 stage or do I need more gain? I was also thinking of triode wiring a 6AU6A as I have a bunch laying around.
I am going to order Rod's regulator boards for the filaments. Are you guys running each parallel channel in series and then the two channels in parallel? Or are you running them all in series? Or all in parallel?
Can I test these on my Hickok 539b? Is the Loctal socket the same?
I bought a whole box of these babies. From Russia with love <3
I am taking the 4P1L plunge. It's been a few years since I built a power amp for myself so I have an itch that needs scratching.
I got Pete's A2 driver board which I will use to directly couple to the output stage. I am certainly going single ended but I have 3k:8 output iron, I should parallel two 4P1L's for this load correct?
Now for the voltage amp section...........I read these are easy to drive no? How much drive signal do I need? The voltage amp will be a common cathode triode with a CCS anode load. Can I get away with a 6SN7 stage or do I need more gain? I was also thinking of triode wiring a 6AU6A as I have a bunch laying around.
I am going to order Rod's regulator boards for the filaments. Are you guys running each parallel channel in series and then the two channels in parallel? Or are you running them all in series? Or all in parallel?
Can I test these on my Hickok 539b? Is the Loctal socket the same?
I bought a whole box of these babies. From Russia with love <3
Attachments
I am going to run A2 mode via Mosfet source followers DC coupled to the 4P1L grids.
I didn't think of using a 4P1L as the voltage gain stage.
I didn't think of using a 4P1L as the voltage gain stage.
How much gain you need? With 4P1L PSE output stage you can use any DHT of 8-10 mu. I’d go for 2P29L,4P1L, 10Y, 01a. All gyrator loaded cap coupled to your mosfet follower for A2 with fixed bias
DHT Drivers with filament bias
If you need a tad more gain: 6e5p or 6e6pdr are my best and favourite drivers
You can degenerate the stage with an unbypassed cathode resistor and works like a charm!
Ale
DHT Drivers with filament bias
If you need a tad more gain: 6e5p or 6e6pdr are my best and favourite drivers
You can degenerate the stage with an unbypassed cathode resistor and works like a charm!
Ale
My sources are about 2v peak so my gain is dependent on A2 to reach say 5 watts from two 4P1L's in parallel. I was thinking I need gain of 20 or more for the voltage amp section?
From the curve tracer on your site I see 30mA @ 250v is roughly -18v bias
From the curve tracer on your site I see 30mA @ 250v is roughly -18v bias
This is what I tried back in 2013:
You need 20Vrms input for 6W output. Therefore a mu of 10-15 should be minimum.
You could push the 4P1L to 300V, which can work fine but keep them on the 9-10W limit. Otherwise they will run noisy and lifespan is reduced.
cheers
Ale
You need 20Vrms input for 6W output. Therefore a mu of 10-15 should be minimum.
You could push the 4P1L to 300V, which can work fine but keep them on the 9-10W limit. Otherwise they will run noisy and lifespan is reduced.
cheers
Ale
Thank you Ale!!!!
Okay so 20vrms is pretty much ballpark for what I thought to get that power. I don't plan to go to 300v, 250v was what I have iron for.
Those curves look like for two in parallel. Wow, 6 watts and 2.5%THD that is great I can't wait to build.
Thanks
Okay so 20vrms is pretty much ballpark for what I thought to get that power. I don't plan to go to 300v, 250v was what I have iron for.
Those curves look like for two in parallel. Wow, 6 watts and 2.5%THD that is great I can't wait to build.
Thanks
Curves are for one 4P1L but I adjusted scale and model to simulate a pair of valves
And yes, the 4P1L is hard to beat!
Keep us posted on your progress
Ale
And yes, the 4P1L is hard to beat!
Keep us posted on your progress
Ale
Especially for the price they seem unbeatable.
I will most likely start a new thread when I get everything ready for my build. This box of tubes makes me feel like a kid at Christmas.
I forgot about the filaments.
Do you run them as a series string? For example if I use 4 tubes in my amp do I run them without the center tap with a CCS of say 300mA? The supply would need to be >16v?
Do you run them as a series string? For example if I use 4 tubes in my amp do I run them without the center tap with a CCS of say 300mA? The supply would need to be >16v?
Yes I want to use Rod's regulators for sure!! But since they are current sources do I run the four 4P1L's in parallel and set the regulator for 1.2A or do I run the tubes a series string and set the regulator for 300mA?
For driver and output stage I run them at 325mA (series) and for preamp in parallel at 550mA (starved) or 650mA.