Good evening all,
I'm hoping a few of the experts will chime in on this subject. I have looked at a number of posts similar to my situation but not identical. I am trying to build a tube preamp that can be used as a line stage or Headphone amp. About a year ago I bought an Aikido Noval (rev F) kit and a PS-21 power supply from GlassWare Audio. Based upon John's suggestions I will be using the JJ ECC802s in the first stage and the JJ ECC99 in the second stage. After I bought the kit I assembled the PS-21. Pretty straight forward. When I started the preamp board things got a lot more confusing for me for 2 reasons. First in the manual there are charts for different tubes....the ECC99 is not in the table. Moreover the ECC802s is not either. I do understand the 12AU7 and the ECC802s are interchangeable. Secondly, when doing double duty as a line stage and a headphone preamp the values of the parts change or are eliminated or jumpers are put in. Very confusing when my combination of tubes are not addressed specifically in the manual. I have tried emailing John a few times but I have not heard back from him.
What I do know: I have 225V coming off of the PS-21 for B+ and 12.6V for the heaters. I have 33uF caps for the 300 ohm headphones and 1uF caps for the line stage. Beyond that things get hazy for the above mentioned reasons. As I said, I did try and look at a similar post (Aikido Noval Rev G) but the schematic labeling is different enough that it doesn't quite make sense. I am no expert when it comes to tubes so I am hoping to rely on some expertise here. I was hoping for a kit I could assemble (easy enough) and listen to. I feel like I have to know preamp design at this point to make any progress. Well I have rambled on so I am going to end it here. Feel free to ask questions if I missed something important.
I'm hoping a few of the experts will chime in on this subject. I have looked at a number of posts similar to my situation but not identical. I am trying to build a tube preamp that can be used as a line stage or Headphone amp. About a year ago I bought an Aikido Noval (rev F) kit and a PS-21 power supply from GlassWare Audio. Based upon John's suggestions I will be using the JJ ECC802s in the first stage and the JJ ECC99 in the second stage. After I bought the kit I assembled the PS-21. Pretty straight forward. When I started the preamp board things got a lot more confusing for me for 2 reasons. First in the manual there are charts for different tubes....the ECC99 is not in the table. Moreover the ECC802s is not either. I do understand the 12AU7 and the ECC802s are interchangeable. Secondly, when doing double duty as a line stage and a headphone preamp the values of the parts change or are eliminated or jumpers are put in. Very confusing when my combination of tubes are not addressed specifically in the manual. I have tried emailing John a few times but I have not heard back from him.
What I do know: I have 225V coming off of the PS-21 for B+ and 12.6V for the heaters. I have 33uF caps for the 300 ohm headphones and 1uF caps for the line stage. Beyond that things get hazy for the above mentioned reasons. As I said, I did try and look at a similar post (Aikido Noval Rev G) but the schematic labeling is different enough that it doesn't quite make sense. I am no expert when it comes to tubes so I am hoping to rely on some expertise here. I was hoping for a kit I could assemble (easy enough) and listen to. I feel like I have to know preamp design at this point to make any progress. Well I have rambled on so I am going to end it here. Feel free to ask questions if I missed something important.
don't know what happen but he didn't respond to any of my email this year where he always replied before. And welcome to the incomplete manual club ...lol...Look like he copies and paste or something that few parts are missing or wrong on the PCB.line stage or Headphone amp
-line stage: No C23 and do not Jumper J9
-Headphone amp: C23, Jumper J9, no R11
line stage AND Headphone amp
-you need a switch for this version
We emailed back and forth about 5 times before I bought the boards, but after that I haven't heard from him. It's a shame because I think he has a great product.
Thats what I'm finding as well. He talks about a part number in the manual but on the board, you can't find it. One example is C23 you referred to.
The other difference I am seeing is the different labeling between the different revisions. You refer to jumper 9 and 11. I don't have that on my revision. So for a non expert (thats me) it is hard to correlate between the different versions.
Yes, for the LSA/HPA version I know you need the switch. I bought that at the time as well.
Thats what I'm finding as well. He talks about a part number in the manual but on the board, you can't find it. One example is C23 you referred to.
The other difference I am seeing is the different labeling between the different revisions. You refer to jumper 9 and 11. I don't have that on my revision. So for a non expert (thats me) it is hard to correlate between the different versions.
Yes, for the LSA/HPA version I know you need the switch. I bought that at the time as well.
I have two Aikido, the first I made in 2004, I designed the PCB myself configuring the tubes coupled horizontally, 4 x 6CG7 + 1 x GZ34 and double virtual battery power supply; the second I closed two days ago, uses 2 x 6CG7 + 2 x 6H30, is a dual-mono building with the PCBs mono rev. G and two PS-21. Actually, I'm waiting for the delay board coming from eBay, hopefully, tomorrow.
Both Aikido are configured as line preamplifiers.
C23 in my manual is C10 in my PCB rev. G.
I'd configure the ECC99 as a 6H30.
Are you still in trouble? Perhaps I can help, just let me know.
Both Aikido are configured as line preamplifiers.
C23 in my manual is C10 in my PCB rev. G.
I'd configure the ECC99 as a 6H30.
Are you still in trouble? Perhaps I can help, just let me know.
Hi, and thanks for the reply. I think with the help of Alashikata we have pretty much squared away the different values. I am actually in the final stages of acquiring parts and have started mockup. Here are a couple of pictures of mockup.
https://i.imgur.com/jUSUnmB.jpg?1
https://i.imgur.com/YLSCxt0.jpg?1
https://i.imgur.com/ll4ixQp.jpg?2
https://i.imgur.com/jUSUnmB.jpg?1
https://i.imgur.com/YLSCxt0.jpg?1
https://i.imgur.com/ll4ixQp.jpg?2
Quite impressive!
I'm glad you solved the issues.
John is a bit imprecise in docs and in shipping the right components. But the projects are very good.
Here is mine, one picture of the first one and three of the second one. No input selector on the second for now, it will be connected only to the computer (Asus Essence STXII w/Muses01-Muses02). But I marked internally the cabinet for drilling, in order to be able to receive 3 more input couples of RCA jack and one more knob.
The cabinet is 4U/400mm from HiFi2000, the pitch of the drilling in the base is 10mm, which fits almost perfectly the holes on the PCBs by GlassWare, I didn't have to adapt them.
I cannot connect the RCA i/o jacks yet because I'm waiting for the delay, a speaker protection whose relay I will use with reverse logic, in order to maintain the output shorted for 2 minutes after power on. I hope it will be delivered tomorrow.
I have one more couple of PCBs rev G. Perhaps my next step will be building a new main amplifier with an Aikido Hi-Gain as front end and a Paragon Follower (Diamond Buffer Triplet) as output stage. No feedback at all but the local ones.
Attachments
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Two of the three heat sinks are for heaters, one PS with its own heat sink serves one channel. The central heat sink is the anodic PS for both channels. This is the PS-21 from GlassWare
Look at my pictures in my last post, the cabinet is a simple thing!
The 3 PCB's are the boards out of this:
AC Mains Line Power Filter LPF-4000 – ATL Audio Ltd.
Board 1 is protection via the MOV's and a relay for on/off
Board 2 is DC blocking and stage 1 of EMI/RFI filtering
Board 3 is stage 2 & 3 of EMI/RFI filtering
Looks awesome! I am using the following case:
Slimline 4U – diyAudio Store
with this baseplate:
Chassis Baseplate (Galaxy, Dissipante, Slimline, Pesante) – diyAudio Store
and these risers:
Riser Panels – diyAudio Store
Interesting, I will also be using shaft extensions. Small world.
I bought the U coupling joints almost 20 years ago when was in Italy, from RS Components. I remember they were expensive, but the only solution to connect the knobs on the front panel.
The pictures don't show, I used a 1/4 bronze bushing in order to let the shaft cross the front panel, I bought it at ACE Hardware store for something less than $4.
I bought the knob 20 years ago too, it is gold-plated solid brass, and I remember it was kind of cheap at that time. I agree with any of you who thinks this will be another "funerary find", if I find a beautiful black knob, I will change it.
Slimline is another HiFi2000 cabinet, sold here. I needed a deeper cabinet (400mm), so I couldn't choose the Slimline but I chose the Pesante. I'm used to buying directly from the HiFi2000 factory, being their customer since 1980. Very interesting the raisers, I put them in my mind!
The pictures don't show, I used a 1/4 bronze bushing in order to let the shaft cross the front panel, I bought it at ACE Hardware store for something less than $4.
I bought the knob 20 years ago too, it is gold-plated solid brass, and I remember it was kind of cheap at that time. I agree with any of you who thinks this will be another "funerary find", if I find a beautiful black knob, I will change it.
Slimline is another HiFi2000 cabinet, sold here. I needed a deeper cabinet (400mm), so I couldn't choose the Slimline but I chose the Pesante. I'm used to buying directly from the HiFi2000 factory, being their customer since 1980. Very interesting the raisers, I put them in my mind!
A doubt on Aikido.
The Aikido circuitry, as well as Gomez, Cascode, and SRPP circuitries have a problem: Half of the heater has a voltage referral negative with respect to its cathode.
The heather is hotter than the cathode so, being the cathode of the upper triode at +b/2, it is seen as an anode by its semi heater, which stays at +b/4. So there will be a current flowing from the heater to the cathode of the upper triode.
For this reason, in my first Aikido, I used the triodes in the same tube coupled horizontally. In this way I could polarize all the heaters at Vk+10V, to say 0+10V for the lower heater, +b/2+10V for the upper heater. Since all the heaters are slightly positive with respect to their cathodes, no current will flow from the heater to the cathode.
All my projects have all the heaters positive with respect to their cathodes. My second Aikido uses the tube as per the design of the PCB, being my first build having a heather negative to its cathode. What should I expect from that?
The Aikido circuitry, as well as Gomez, Cascode, and SRPP circuitries have a problem: Half of the heater has a voltage referral negative with respect to its cathode.
The heather is hotter than the cathode so, being the cathode of the upper triode at +b/2, it is seen as an anode by its semi heater, which stays at +b/4. So there will be a current flowing from the heater to the cathode of the upper triode.
For this reason, in my first Aikido, I used the triodes in the same tube coupled horizontally. In this way I could polarize all the heaters at Vk+10V, to say 0+10V for the lower heater, +b/2+10V for the upper heater. Since all the heaters are slightly positive with respect to their cathodes, no current will flow from the heater to the cathode.
All my projects have all the heaters positive with respect to their cathodes. My second Aikido uses the tube as per the design of the PCB, being my first build having a heather negative to its cathode. What should I expect from that?
Caution, the metal foil resistors pictured cause much more distortion than other resistors.
recommend to use Vishay PTF-(65) metal film resistors, they cause much lower distortion than the metal foil resistors do.
The lower the thermal coefficient the better.
Thanks DT
search the DIYaudio site for thread on resistor distortion
recommend to use Vishay PTF-(65) metal film resistors, they cause much lower distortion than the metal foil resistors do.
The lower the thermal coefficient the better.
Thanks DT
search the DIYaudio site for thread on resistor distortion
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These are the audio path resistors. These Vishay TX2575 are known for their stellar audio quality. Are their better? Sure, I just wasn't going to spend almost $30.00 a resistor. Their TCR is .2ppm. Here is a link to the datasheet.
https://www.partsconnexion.com/media/pdfs/vishay_var.pdf
https://www.partsconnexion.com/media/pdfs/vishay_var.pdf
In all of my projects, where they fit, I use Vishay MBB/SMA 207 professional 1% 0.6W Metal Film I find them on the Mouser site. Their cost is an average of 25c apiece, buying a batch of 10 you can save some money. They are not that cheap but the quality is high.
I would not spend any more money.
They fit is my Aikido with 6CG7 & 6H30 and the sound is great.
I would not spend any more money.
They fit is my Aikido with 6CG7 & 6H30 and the sound is great.
The Vishay PTF resistors are much less expensive than the Vishay metal foil resistors.
Read this article by Bruce Hoffer of Audio Precision:
https://hifisonix.com/wordpress/wp-content/uploads/2017/11/Designing_for_Ultra-Low_THD_N-1.pdf
There are big claims for Vishay metal film resistors, measurements show that the claims may be true for DC. At AC they measure nearly as bad as Carbon Compound resistors.
Thanks DT
Look at this thread for resistor distortion and Vishay foil resistor distortion measurements.
https://www.diyaudio.com/forums/parts/347259-causes-resistor-distortion-23.html#post6101327
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