Hi Marc,
I have bought your PCB (which looks good and very good documented) and figuring out which tube to choose for this project. I like a good controlled bas, so i was thinking on 6CA7, or 6550 / KT88 for even more low end control. You tried several tubes and didn't like the KT88 in this design. How does it sound? Compare to the 6CA7 and 6550.
I would like to built everything om top of the chassis. Is this possible, also considering into account the heat dissipation of some components such as the 4W resistor, R27.
In the Baby Huey EL84 version the C1 and C2 capacitors are 0.22uF. In this EL34 version they are 0.1uF. Is this correct?
Thanks.
René
Bonjour René,
Thank you for your nice comment about the PCB and the documentation, I try to do my best even if English is not as easy as French for me
Regarding output tubes it is really dependent of the preference of each one, personally I have been very impressed by the sound of the amplifier with the 6V6S and the 6CA7, both new production from JJ bought at Banzai Music GmbH I haven't tested the 6550 on the Baby Huey (because they are on my Jolida JD-502B) but I tested the KT88 on one channel and I have preferred the 6CA7. I have also used the same KT88 on my Jolida and I also preferred the 6550... The KT88 were also from JJ while the 6550 were from Sovtek !
I have also read in a review of the Jolida that the KT88 are fragile : "This axiom proved to be true, alas, with the KT88's. The '88's, it turns out are fragile tubes, and are often damaged in shipping. On two occasions, I experienced failure of KT88's. The upside of this is that I experienced firsthand the durability and reliability of the JD-502B: nothing major or catastrophic, just a change of the line fuse and a tube change and everything was up and running again. According to Mike Allen, the internal structure of the KT88 is quite fragile, and if a set of tubes survives the first 30 days of use, they should last years. While I loved the sound of the JD-502B with KT88s, I couldn't live with the reliability issue of the KT-88's and substituted a set of Sovtek 6550's for the remainder of the review, where they performed flawlessly."
May be the KT90 or the KT120 could be a solution, but I don't believe that this architecture is for a very high power amplifier with more than 500V plates voltage, may be I will design one later with a quad output like the Norman Koren "TENA amplifier" ?
I have read from a builder of the first batch of PCB that the KT66 is a good candidate, I have not bought this tube yet, but I may try it some time. Tung-sol version seems to be very good : www.thetubestore.com - KT66 Tube Review
You can build the amplifier with the tubes on the top, I have mounted only the low profile components on the top side, but it is also possible to put all components on the bottom side, but be carefull with the transistor orientation! The power dissipation of the 4W resistor is not very high if you are using a 10 ohms, if you prefer, you can mount it on the bottom, you can even connect a 5 to 10 Henry choke for a C-L-C filter.
C1 and C2 can be any value higher than 0.1 uF 400V, the 0.22 uF I had were 630V and were too big to fit on the PCB, that's why I used the 0.1 uF. Again you can choose what you prefer, or what you have
Cheers,
Marc
Thank you for your nice comment about the PCB and the documentation, I try to do my best even if English is not as easy as French for me
Regarding output tubes it is really dependent of the preference of each one, personally I have been very impressed by the sound of the amplifier with the 6V6S and the 6CA7, both new production from JJ bought at Banzai Music GmbH I haven't tested the 6550 on the Baby Huey (because they are on my Jolida JD-502B) but I tested the KT88 on one channel and I have preferred the 6CA7. I have also used the same KT88 on my Jolida and I also preferred the 6550... The KT88 were also from JJ while the 6550 were from Sovtek !
I have also read in a review of the Jolida that the KT88 are fragile : "This axiom proved to be true, alas, with the KT88's. The '88's, it turns out are fragile tubes, and are often damaged in shipping. On two occasions, I experienced failure of KT88's. The upside of this is that I experienced firsthand the durability and reliability of the JD-502B: nothing major or catastrophic, just a change of the line fuse and a tube change and everything was up and running again. According to Mike Allen, the internal structure of the KT88 is quite fragile, and if a set of tubes survives the first 30 days of use, they should last years. While I loved the sound of the JD-502B with KT88s, I couldn't live with the reliability issue of the KT-88's and substituted a set of Sovtek 6550's for the remainder of the review, where they performed flawlessly."
May be the KT90 or the KT120 could be a solution, but I don't believe that this architecture is for a very high power amplifier with more than 500V plates voltage, may be I will design one later with a quad output like the Norman Koren "TENA amplifier" ?
I have read from a builder of the first batch of PCB that the KT66 is a good candidate, I have not bought this tube yet, but I may try it some time. Tung-sol version seems to be very good : www.thetubestore.com - KT66 Tube Review
You can build the amplifier with the tubes on the top, I have mounted only the low profile components on the top side, but it is also possible to put all components on the bottom side, but be carefull with the transistor orientation! The power dissipation of the 4W resistor is not very high if you are using a 10 ohms, if you prefer, you can mount it on the bottom, you can even connect a 5 to 10 Henry choke for a C-L-C filter.
C1 and C2 can be any value higher than 0.1 uF 400V, the 0.22 uF I had were 630V and were too big to fit on the PCB, that's why I used the 0.1 uF. Again you can choose what you prefer, or what you have
Cheers,
Marc
Hi Marc,
You should really try the Electroharmonix line of tubes. Better than JJ. I haven't had any KT88 failures yet for several brands that have been shipped.
If you try the KT66, also try the 7581A. Similar tube, same plate dissipation, but it has the same characteristics as the 6L6GC. The KT66 differs a little. Interestingly, the Electroharmonix 6L6EH plate structure is much like a 7581A, and I have used these tubes (6L6EH) in tough situations - like Fender Twin amplifiers, and they work well with no hint of overheated plates.
-Chris
You should really try the Electroharmonix line of tubes. Better than JJ. I haven't had any KT88 failures yet for several brands that have been shipped.
If you try the KT66, also try the 7581A. Similar tube, same plate dissipation, but it has the same characteristics as the 6L6GC. The KT66 differs a little. Interestingly, the Electroharmonix 6L6EH plate structure is much like a 7581A, and I have used these tubes (6L6EH) in tough situations - like Fender Twin amplifiers, and they work well with no hint of overheated plates.
-Chris
Wow, I really need to get around to building my BH. I've had the schematics I want to build above my workbench for such a long time now, I just need to get around to actually building it. How do y'all get that little kick in the butt that you need to actually buy the parts and start a project?
I clean up my workbench, then put on some shiny new parts. Things tend to just keep going from there.
Hi Adam,
You just do.
What I find is helpful is to label small-ish boxes with the project name and as I gather information and parts, I throw them in that box (which closes so you don't lose anything). I typically might have 5 or so projects on the go and this really helps me stay organised.
Once you have everything you need, just note that on the box and dive into it when you feel like starting. It really helps if the boxes are all the same size so they stack neatly. At this moment in time, I have 7 projects waiting for parts or some input from someone. I can look up and see everything so I remember to order parts or contact a person. Two projects are waiting for metal work. Nothing I can do about that but wait.
I guess the other thing the box does is allow you to work on the project, then store it for more work later on. Again, you don't lose anything this way.
-Chris
You just do.
What I find is helpful is to label small-ish boxes with the project name and as I gather information and parts, I throw them in that box (which closes so you don't lose anything). I typically might have 5 or so projects on the go and this really helps me stay organised.
Once you have everything you need, just note that on the box and dive into it when you feel like starting. It really helps if the boxes are all the same size so they stack neatly. At this moment in time, I have 7 projects waiting for parts or some input from someone. I can look up and see everything so I remember to order parts or contact a person. Two projects are waiting for metal work. Nothing I can do about that but wait.
I guess the other thing the box does is allow you to work on the project, then store it for more work later on. Again, you don't lose anything this way.
-Chris
Hi all,
For those who may have missed the first GB for the Baby Huey PCB, there is a new one now
As you can see on the pictures below this PCB can be used with 6CA7, KT88, 6V6, or many other compatible output pentode or tetrode tubes...
Please have a look here GB for Baby Huey PCB if you are interested, it will close beginning of January and will be the last one
Happy New-year,
Marc
For those who may have missed the first GB for the Baby Huey PCB, there is a new one now
As you can see on the pictures below this PCB can be used with 6CA7, KT88, 6V6, or many other compatible output pentode or tetrode tubes...
Please have a look here GB for Baby Huey PCB if you are interested, it will close beginning of January and will be the last one
Happy New-year,
Marc
Attachments
Hello Patrick,
I understand your point but I don't think it is necessary to make another thread since the most interesting aspect of the Baby Huey is its "shunt feedback" design !
If this concept started by Ian (gingertube) more than 10 years ago was built around EL84 and 6V6GT tubes, there were already ECL86 versions designed by Yves and my EL34 version was mainly a variation of the "EL34 Music Angel" modified by Ian long time ago...
My initial project was to design a very simple PCB for a PCL86 version because I am not very good in wire to wire soldering but after this experience I was so impressed by the result that I have designed a more sophisticated version with the EL84 and the MOSFET...
Again, I was very happy with the result and wanted to try a more powerful solution with EL34 tubes ! After the first test and photos of this amplifier I got several inquiries to sell PCB and the moderator move the subject to a GB thread...
I had never made a GB and I didn't know how to use PayPal but the large success for this small PCB forced me to learn and finally 80 PCB's were ordered and shipped
Since many people missed the first batch, I decided to make a second and last one because it is time consuming and I want to test other things. We have already 60 PCB's ordered !
The purpose of this amplifier PCB is to make it simple enough to built a tube stereo amplifier by adding only the power transformer and the output transformers. It is also easy to make some improvement like using a DC power supply for heater or to test different output tubes. In fact several buyers told me that this is their first amplifier with vacuum tubes
I hope all the people who are building it will like the result like me and several builders that gave me their feedback.
I wish you all an Happy New Year
Marc
I understand your point but I don't think it is necessary to make another thread since the most interesting aspect of the Baby Huey is its "shunt feedback" design !
If this concept started by Ian (gingertube) more than 10 years ago
was built around EL84 and 6V6GT tubes, there were already ECL86 versions designed by Yves and my EL34 version was mainly a variation of the "EL34 Music Angel" modified by Ian long time ago...My initial project was to design a very simple PCB for a PCL86 version because I am not very good in wire to wire soldering
but after this experience I was so impressed by the result that I have designed a more sophisticated version with the EL84 and the MOSFET...Again, I was very happy with the result and wanted to try a more powerful solution with EL34 tubes ! After the first test and photos of this amplifier I got several inquiries to sell PCB and the moderator move the subject to a GB thread...
I had never made a GB and I didn't know how to use PayPal but the large success for this small PCB forced me to learn and finally 80 PCB's were ordered and shipped
Since many people missed the first batch, I decided to make a second and last one because it is time consuming and I want to test other things. We have already 60 PCB's ordered !
The purpose of this amplifier PCB is to make it simple enough to built a tube stereo amplifier by adding only the power transformer and the output transformers. It is also easy to make some improvement like using a DC power supply for heater or to test different output tubes. In fact several buyers told me that this is their first amplifier with vacuum tubes
I hope all the people who are building it will like the result like me and several builders that gave me their feedback.
I wish you all an Happy New Year
Marc
So I am in the group buy and now looking at a parts list. For those more knowledgeable in tubes than I, would this transformer from Antek be suitable? AS-2T230 - 200VA 230V Transformer - AnTek Products Corp It appears the 6.3vac secondary would handle one mono amp. A pair of these if ok to use could supply plate and filament voltages.
For the original EL84 amp , I would estimate a bare minimum of 125VA , preferably 150VA per channel for monoblocks and a 225VA for a stereo amp (assuming a SS rectifier)
316a
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I originally posted this on the GB thread. This is probably the better choice.
For El34 build:
Started the ordering process. Here is a Mouser project cart Mouser Electronics
What is missing are C6, C7, C10, C11 Those Nichicon caps are not in stock at Mouser, you may be able to find suitable subs. I just went to Digikey and ordered all of these caps, which they have in stock. Adds a bit for shipping and sales tax, instead of one stop shopping.
The numbers in the Mouser order are for a Stereo build, so twice as many parts as the BOM Marc has posted.
What is still needed, would be tubes, sockets, transformers/PS.
Combined Mouser and Digikey orders with shipping is around 110usd. I found matched quad sets of EL34 tubes 70usd, Pair of EEC88 tubes 25-30usd, Hammond 1650N output xformer pair 263usd and going with separate power, spec a Hammond power xformer a pair of 370HX (covers plate, bias, and filament in one package) 271usd. Six ceramic sockets about 20usd.
Would someone with more tube knowledge please confirm for me if the Hammond 370HX is what is needed for a EL34/EEC88 build? Is it too much or too little? Hammond Mfg. - Universal Primary - "Classic" Power Transformers
For El34 build:
Started the ordering process. Here is a Mouser project cart Mouser Electronics
What is missing are C6, C7, C10, C11 Those Nichicon caps are not in stock at Mouser, you may be able to find suitable subs. I just went to Digikey and ordered all of these caps, which they have in stock. Adds a bit for shipping and sales tax, instead of one stop shopping.
The numbers in the Mouser order are for a Stereo build, so twice as many parts as the BOM Marc has posted.
What is still needed, would be tubes, sockets, transformers/PS.
Combined Mouser and Digikey orders with shipping is around 110usd. I found matched quad sets of EL34 tubes 70usd, Pair of EEC88 tubes 25-30usd, Hammond 1650N output xformer pair 263usd and going with separate power, spec a Hammond power xformer a pair of 370HX (covers plate, bias, and filament in one package) 271usd. Six ceramic sockets about 20usd.
Would someone with more tube knowledge please confirm for me if the Hammond 370HX is what is needed for a EL34/EEC88 build? Is it too much or too little? Hammond Mfg. - Universal Primary - "Classic" Power Transformers
Hi drpro,
There is an alternative to an expensive tubes power supply transformer, you can use a regular high voltage transformer with a secondary between 230 and 275 V and a power of 125 to 150 VA (more power for a stereo set is useless because you don't have the 50 t0 60 VA normally required for the heaters !) and a compact 6.3 V 10 A switching power supply for the heaters. This is what I have done and you have absolutely no hum on your amplifier Here is the power supply that I am using, sorry it is in french, it work very well with two 6CA7 or two KT88 with a heater current of about 7 A for the stereo set : Bloc de Chauffage 6,3 V / 10 A Régulé pour Ampli à Tubes AL0007 : RADIOELEC : Composants et Modules Electroniques, spécialiste Audiophiles et Radioamateurs I buy it in France but it is manufactured in China of course
You will still need a small transformer to supply the negative bias and the positive MOSFET driver stage, a 10 VA 2 x 24 V AC connected in serie will give about +65 V DC and -65 V DC after the rectifiers and the capacitors on the board, which is perfect !
For the output transformer I am using a Hammond 1650N too, but their price is now too expensive and one of the builder has used with success the Toroidy transformer : TTG-EL34PP TOROIDY - Transformateur: de haut-parleur | TME - Composants electroniques at 6.6k primary it will be more interesting for 6L6 or KT66, for EL34 or KT88 I will prefer this one : TTG-KT88PP TOROIDY - Transformateur: de haut-parleur | TME - Composants electroniques it is a 4k version...
These are only suggestions there is a lot of possibility, it depend also of the tubes that you are using !
Cheers,
Marc
There is an alternative to an expensive tubes power supply transformer, you can use a regular high voltage transformer with a secondary between 230 and 275 V and a power of 125 to 150 VA (more power for a stereo set is useless because you don't have the 50 t0 60 VA normally required for the heaters !) and a compact 6.3 V 10 A switching power supply for the heaters. This is what I have done and you have absolutely no hum on your amplifier
Here is the power supply that I am using, sorry it is in french, it work very well with two 6CA7 or two KT88 with a heater current of about 7 A for the stereo set : Bloc de Chauffage 6,3 V / 10 A Régulé pour Ampli à Tubes AL0007 : RADIOELEC : Composants et Modules Electroniques, spécialiste Audiophiles et Radioamateurs I buy it in France but it is manufactured in China of course You will still need a small transformer to supply the negative bias and the positive MOSFET driver stage, a 10 VA 2 x 24 V AC connected in serie will give about +65 V DC and -65 V DC after the rectifiers and the capacitors on the board, which is perfect !
For the output transformer I am using a Hammond 1650N too, but their price is now too expensive and one of the builder has used with success the Toroidy transformer : TTG-EL34PP TOROIDY - Transformateur: de haut-parleur | TME - Composants electroniques at 6.6k primary it will be more interesting for 6L6 or KT66, for EL34 or KT88 I will prefer this one : TTG-KT88PP TOROIDY - Transformateur: de haut-parleur | TME - Composants electroniques it is a 4k version...
These are only suggestions there is a lot of possibility, it depend also of the tubes that you are using !
Cheers,
Marc