Unhappy with the LIlliput design
First of all, to be fair, i didn't use Megahertz transformers, i did use a Hammond 125 ESE with the 2,5k secondary tap connected to my 8 Ohms, 97db/m, speaker.
Results were dissapointing, not that it sounds bad but frankly, my ecl86 SE sounds a lot better using the 125 ESE as well.
The operating point of the input tube, a NOS GE 6dj8, was changed as it didn't have enough gain as it was. Replaced the 1K bias resistor for a 330 ohms. Sound is kind of dark or "fat" i'm not very good with audio adjectives but it doesn't have the "live" sound of my ecl86 SE.
Would using the Megahertz transformer be a total change? For it must get a LOT better to make me happy. Maybe this tube it's not of my liking. Before spending 200 euros in those transformers i want to know it's going to sound better than my ecl86-125Ese cheapo amp.
Is really the 6AS7 better sonically than a ecl86? I'm beginning to doubt this.
Any ideas?
Also , can i use the 6AS7 as a rectifier in case i just forget about this amp?
Thanks.
First of all, to be fair, i didn't use Megahertz transformers, i did use a Hammond 125 ESE with the 2,5k secondary tap connected to my 8 Ohms, 97db/m, speaker.
Results were dissapointing, not that it sounds bad but frankly, my ecl86 SE sounds a lot better using the 125 ESE as well.
The operating point of the input tube, a NOS GE 6dj8, was changed as it didn't have enough gain as it was. Replaced the 1K bias resistor for a 330 ohms. Sound is kind of dark or "fat" i'm not very good with audio adjectives but it doesn't have the "live" sound of my ecl86 SE.
Would using the Megahertz transformer be a total change? For it must get a LOT better to make me happy. Maybe this tube it's not of my liking. Before spending 200 euros in those transformers i want to know it's going to sound better than my ecl86-125Ese cheapo amp.
Is really the 6AS7 better sonically than a ecl86? I'm beginning to doubt this.
Any ideas?
Also , can i use the 6AS7 as a rectifier in case i just forget about this amp?
Thanks.
is the tube that makes the sound?
No, it is the curcuit.
That means first of all schematic, working point, components quality. The tube itself makes very little in this whole picture.
Lilliput is reputed to be good sounding budget amplifier. Hammond's 125 series OPT are not HI-Fi rated, as the same manufactor specify. Also changing the working point of the driver alters the tonal balance because I guess that the original design use a certain amount of harmonic cancellation.
The input sensitivity is 2.7V rms that should be enough with direct CD input and 97dB efficient speaker.
A try with better output transformer in my opinion should be done before to blame this project.
No, it is the curcuit.
That means first of all schematic, working point, components quality. The tube itself makes very little in this whole picture.
Lilliput is reputed to be good sounding budget amplifier. Hammond's 125 series OPT are not HI-Fi rated, as the same manufactor specify. Also changing the working point of the driver alters the tonal balance because I guess that the original design use a certain amount of harmonic cancellation.
The input sensitivity is 2.7V rms that should be enough with direct CD input and 97dB efficient speaker.
A try with better output transformer in my opinion should be done before to blame this project.
The sound got better but stilll...the problem is i use a low level output source(less than 1volt). Also my transformer only allows for 80 mil DC bias and i guess is on the limit thus not sounding very good or as good as it did with 35m DC bias. At low volumes sounds ok but the problem is i like music LOUD.
I will make a pre and report results....thinking about the aikido by John Broskie and see if the amp really sings with a 2v input.
Haven't got a cd player as i fried mine in a stupid mod i tried.
Thanks for the reply.
Cheers,
aLVARO
I will make a pre and report results....thinking about the aikido by John Broskie and see if the amp really sings with a 2v input.
Haven't got a cd player as i fried mine in a stupid mod i tried.
Thanks for the reply.
Cheers,
aLVARO
Parafeed or BIRSEP
Yea, the transformer reach its limits and you got saturation.You can try simply to add a inductore and use the 125ESE as parafeed, avoiding DC current troubles. See RDH4 to proper dimension inductance and coupling cap.
To have more power and sensitivity, on the same magazine that published Lilliput, a reader proposed a PSE version , called Birsep, with two section of 6080 paralleled and a cascaded Ecc88 driver.
The response curve and distortion are good and power is 6W.
Seek on Costruire Hi Fi (CHF) on some volume of this Years I think.
Yea, the transformer reach its limits and you got saturation.You can try simply to add a inductore and use the 125ESE as parafeed, avoiding DC current troubles. See RDH4 to proper dimension inductance and coupling cap.
To have more power and sensitivity, on the same magazine that published Lilliput, a reader proposed a PSE version , called Birsep, with two section of 6080 paralleled and a cascaded Ecc88 driver.
The response curve and distortion are good and power is 6W.
Seek on Costruire Hi Fi (CHF) on some volume of this Years I think.
stalker said:
Due to the relatively high cost of parafeed chokes, we got some of the IXYS CCS chips to see how that works....
http://pmillett.addr.com/current_source.htm
dave
stalker said:
Simple is here:
http://213.156.45.208/primo/Radiotron.asp
read first the index and dowload the chapter You want because are large PDF files.
Send me a private message, I can send You the schematic of this variant.
Bye,
Ummm, interesting article but i think i'd just rather spend the money in a choke. I like the old style best... Anyway good experiment and great web page. Thanks for the link.
Plovati, i have downloaded all the chapters and will read it.
.
Thanks because i couldn't find it in the net. I am sending you an email.
Cheers,
EDIT: i don't have access to your email address.
Hi, just wanted to say thanks to Plovati for providing me a schematic for the 6as7. Sounds great, i was unfair with the lilliput, i just needed more volts and a good driver stage.
You were right Plovati, it's the circuit not the valve. But what madness to get a good sound, for example if i leave both cathodes of the 6dj8 unbypassed the tone is not there anymore, great sound depends on such a little thing?
Well after 3 months of trying i finally have a great amp, i was about to give the 6as7 up. Thanks again Plovati. My next step would be to buy the Megahertz transformers. If it sounds great with the 2,5k tap from the Hammond 125 ESE, guess it would sound superb with those OT's.
Ciao,
Álvaro
You were right Plovati, it's the circuit not the valve. But what madness to get a good sound, for example if i leave both cathodes of the 6dj8 unbypassed the tone is not there anymore, great sound depends on such a little thing?
Well after 3 months of trying i finally have a great amp, i was about to give the 6as7 up. Thanks again Plovati. My next step would be to buy the Megahertz transformers. If it sounds great with the 2,5k tap from the Hammond 125 ESE, guess it would sound superb with those OT's.
Ciao,
Álvaro
Nice to know You're satisfied.
About yours question on tone with or without bypass cap, I need to understand if You've realized the original Lilliput (one section of 6DJ8 and 6AS7, 2,5kohm load) or the Birsep (two section parallelled, 1kohm load). The last is due to Sergio Birello and was published on italian magazine CHF with also the winding details of output transformer.
6AS7 is a choice of many smart designer that does not care about appearance, with the two section paralleled is a sort of super cheap 300B. But this tube require a current plenty driver and a harmonic cancellation, so choice of operating point and components (bypass cap for example) is essential to have a good tone.
Also a good power supply makes the difference. Power supply transformer must be realized by competent people. Pay attention to upgrade to too expensive components, this schematic may not worth the cost. 6AS7 with some other driver and power supply may instead have beneficial from some top quality parts, but in this case my advice is to buy a used Kiom AD1 amplifier from Luca Chiomenti.
About yours question on tone with or without bypass cap, I need to understand if You've realized the original Lilliput (one section of 6DJ8 and 6AS7, 2,5kohm load) or the Birsep (two section parallelled, 1kohm load). The last is due to Sergio Birello and was published on italian magazine CHF with also the winding details of output transformer.
6AS7 is a choice of many smart designer that does not care about appearance, with the two section paralleled is a sort of super cheap 300B. But this tube require a current plenty driver and a harmonic cancellation, so choice of operating point and components (bypass cap for example) is essential to have a good tone.
Also a good power supply makes the difference. Power supply transformer must be realized by competent people. Pay attention to upgrade to too expensive components, this schematic may not worth the cost. 6AS7 with some other driver and power supply may instead have beneficial from some top quality parts, but in this case my advice is to buy a used Kiom AD1 amplifier from Luca Chiomenti.
A mix, the driver section from the Birsep and the 6as7 just like in the Lilliput, due to the fact that my OT couldn't handle 120mA.
But this tube require a current plenty driver and a harmonic cancellation, so choice of operating point and components (bypass cap for example) is essential to have a good toneQUOTE]But this tube require a current plenty driver and a harmonic cancellation, so choice of operating point and components (bypass cap for example) is essential to have a good tone[/QUOTE]
Yes, i totally agree. I designed a line stage with also a 6dj8, had the gain but not the sonics. The birsep driver section works for me, and i don't get it cause it keeps the 6dj8 at the bottom of the curves, with little current. Basically i have now a Lilliput but with another driver stage which i may remove in the future when i buy a decent CD. We'll see.
As for the Kiom AD1 kit i just couldn't find it in the net. Kiom web page doesn't work.
Do you think the sound will improve with a tube rectifier? T
A mix, the driver section from the Birsep and the 6as7 just like in the Lilliput, due to the fact that my OT couldn't handle 120mA.
But this tube require a current plenty driver and a harmonic cancellation, so choice of operating point and components (bypass cap for example) is essential to have a good toneQUOTE]]
Yes, i totally agree. I designed a line stage with also a 6dj8, had the gain but not the sonics. The birsep driver section works for me, and i don't get it cause it keeps the 6dj8 at the bottom of the curves, with little current. Basically i have now a Lilliput but with another driver stage which i may remove in the future when i buy a decent CD. We'll see.
As for the Kiom AD1 kit i just couldn't find it in the net. Kiom web page doesn't work.
Do you think the sound will improve with a tube rectifier i n the power supply? I will have to get another trafo.
Ciao,
álvaro.
As driver You can try also E180F in triode mode.
I think Lilliput is not the best circuit to be tube supplied, too much current. You should improve more with better output transformer, with high DC current capability, so it can be ready for Birsep (1-1,25kokm, 120mA) using the 8 ohm speaker on 16 ohm connection (or 4 in 8 ohm output).
I think Lilliput is not the best circuit to be tube supplied, too much current. You should improve more with better output transformer, with high DC current capability, so it can be ready for Birsep (1-1,25kokm, 120mA) using the 8 ohm speaker on 16 ohm connection (or 4 in 8 ohm output).
Birsep Schematic
For reference this is the schematic, work of Sandro Birello and friends:
http://img369.imageshack.us/img369/5779/birsep8mn.png
and the output transformer wiring details:
http://img367.imageshack.us/img367/3645/birsepout9gk.png
PS how I can direc insert some picture in my messages?
For reference this is the schematic, work of Sandro Birello and friends:
http://img369.imageshack.us/img369/5779/birsep8mn.png
and the output transformer wiring details:
http://img367.imageshack.us/img367/3645/birsepout9gk.png
PS how I can direc insert some picture in my messages?
Ok, i'll leave the power supply as it is, i have 1,300uf , and AC for the filaments; 97db driver and very little hum, you don't hear it if you're not really close to the speaker.
Yes, i am going to try other valves. Right now, i'm using a 60's 6dj8, GE, it's black; i'll post a pic when i paint the chassis.
I had several NOS pcl86 and the best (by far) was a Siemens. I may buy that 6922 someday. Thanks for the tip.
Can't help here, have no idea.
stalker said:
Huge cap for a single 6080/6as7 section per channel. Power supply transformer must be able to support capacitor charging current without saturate. See the chap 4 of Lee book here:
http://www.cdsoftware.it/primo/materiale/20_060_050_001_Lee_cap4lowres.pdf
Maybe that lower cap (150uF+470uF) works better, or a low ohm (3 to 22ohm) resistor in series before the huge reservoir cap may reduce hum a little bit.
Happy with the Lilliput
Hi Plovati:
1.300 uf were the total capacitance in the power supply, i have a 100uf +220 Ohms + 1000uf sprague cap going to the plate of the 6as7 then i only use 100 uf caps for the driver section.
Anyway i've found out that you can hear every single change in the power supply, thing which amazes me. I did replace the 220 resistor for a 330 Ohm which was 5w instead of the 220 2 watts i was using,well, guess what, i had to put back the 220 resistor cause the sound changed for worse.
Thanks for the link, i will read it. Anyway i did an AC rewiring, and the hum is almost gone now. It doesn't bother me, i can only hear it at night with the house completely quiet , and ,of course, no music on. A choke will get rid of that.
Ciao,
álvaro.
Hi Plovati:
1.300 uf were the total capacitance in the power supply, i have a 100uf +220 Ohms + 1000uf sprague cap going to the plate of the 6as7 then i only use 100 uf caps for the driver section.
Anyway i've found out that you can hear every single change in the power supply, thing which amazes me. I did replace the 220 resistor for a 330 Ohm which was 5w instead of the 220 2 watts i was using,well, guess what, i had to put back the 220 resistor cause the sound changed for worse.
Thanks for the link, i will read it. Anyway i did an AC rewiring, and the hum is almost gone now. It doesn't bother me, i can only hear it at night with the house completely quiet , and ,of course, no music on. A choke will get rid of that.
Ciao,
álvaro.
Re: Happy with the Lilliput
Sometimes, in such simple SE tube design, You can hear the difference between some brand of capacitor, same technology, same value.
So no wonder that if you cahnge a resistor value the sound change, You're moving the operating poit of the tube!
.
stalker said:Hi Plovati:
I did replace the 220 resistor for a 330 Ohm which was 5w instead of the 220 2 watts i was using,well, guess what, i had to put back the 220 resistor cause the sound changed for worse.
Sometimes, in such simple SE tube design, You can hear the difference between some brand of capacitor, same technology, same value.
So no wonder that if you cahnge a resistor value the sound change, You're moving the operating poit of the tube!
Reading it is a good thing, studying it is a better onestalker said:
.