I'll email you in the next couple of days.HiFiNutNut said:
The Wright Superreg design is published on his site as part of the Lenehan amp schematics iirc.
Still buy the book though, it's a good read.
I join this thread late. Wanted to make some comments about the LSDY power reg kit.
I have made three sets of the LSDY power reg kit and had been using them for a few months. None failed yet
I measure the cathode of the of the 12AT7 and it is 134V. I am usng 250V and hence the cathode of the 12B4A is 250V. Since the 12.6 voltage heater supply is common to both tubes, and if it is floating, then the heater to cathode voltage is unknown. Should I then perhaps tie the heater to cathode of the 12AT7? No issue then with the 12AT7 but for the 12B4, it would be 134-250 = -166V. This is within the limit of the 12B4A ( -200V ). So I guess the regulator is OK if I do not go much higher than 250V. If I were to have a voltage divider bias the heater at a known voltage in between say 134 + 100=234V, then maybe I can get higher voltages, up to a max of 100+200+134V= 434V. Am i wrong in my logic?
In my kit, the initial cap is 330uF, not 220u as per the circuit. The datasheet of the 6Z4 says 8uF. So far none of my 6Z4 have died yet. Must be a very robust tube. Anyway, they cost USD1.20 each in China and I have loads. No worry then.
BTW, I have made the following preamps from the liteaudio website, the LS12, LS7B, LS26, LS31, LS9. All of them sound different. Some upgrade of the components, use good NOS tubes and they sound good ( better than all my preamp creations anyway - I am still learning ).
Hope my experience is useful.
I have made three sets of the LSDY power reg kit and had been using them for a few months. None failed yet
I measure the cathode of the of the 12AT7 and it is 134V. I am usng 250V and hence the cathode of the 12B4A is 250V. Since the 12.6 voltage heater supply is common to both tubes, and if it is floating, then the heater to cathode voltage is unknown. Should I then perhaps tie the heater to cathode of the 12AT7? No issue then with the 12AT7 but for the 12B4, it would be 134-250 = -166V. This is within the limit of the 12B4A ( -200V ). So I guess the regulator is OK if I do not go much higher than 250V. If I were to have a voltage divider bias the heater at a known voltage in between say 134 + 100=234V, then maybe I can get higher voltages, up to a max of 100+200+134V= 434V. Am i wrong in my logic?
In my kit, the initial cap is 330uF, not 220u as per the circuit. The datasheet of the 6Z4 says 8uF. So far none of my 6Z4 have died yet. Must be a very robust tube. Anyway, they cost USD1.20 each in China and I have loads. No worry then.
BTW, I have made the following preamps from the liteaudio website, the LS12, LS7B, LS26, LS31, LS9. All of them sound different. Some upgrade of the components, use good NOS tubes and they sound good ( better than all my preamp creations anyway - I am still learning ).
Hope my experience is useful.
SY spotted that problem in the LSDY and recommended using separate heater supplies. I observed that the heater supply is floating but don't know how to work out its voltage. Definitely the difference in the voltage of the heater and cathode of one of the tubes has to be large if only one heater supply is used for the 2 tubes. In my view the simplest solution is to buy an inexpensive, small transformer with 2 x 0-12V windings and power the 2 heaters separately. I have not perused this further because I am no longer interested in the LSDY.
I also heard that liteaudio uses LSDY to power up most of their tube preamps and has been selling completed products. They said they never had problems.
But in any case, I tried it, in replace of the cheap Jaycar one that coverts 12VDC to regulated 260VDC. In the process I also ditched the cathode bypass cap of the 12AX7.
Surprised, surprised, surprised! The sound was completely different from what it used to be. I mean it - completely different. I don't know if it is better or worse. I was used to my tower speaker of which the active XO is being rebuilt / fine-tuned so I could only use the BBC monitor Rogers Studio 1A for the test. I have not used the Rogers for sometime and I much prefer the sound of my tower speaker. For the preamp with the LSDY, some areas are substantially better and some areas much worse. How correct that Frank said that PSU gives 55% of the sound!
On the good side, "Presence" is superb! The sound is much more "fat" than thin, much more tubey, sounding thick, warm, rounded while maintaining good treble and bass. I had one such CD with a violin and a piano that sounded so good in the HiFi showroom when I bought my Rogers 10 years ago, but never sounded good on any other systems regardless of prices. This time after fitting in the LSDY that particular sound track sounded great! On the bad side, transparency and focus seem to be much worse (this could partly be due to using the Rogers rather than my tower speaker). This is the sound a few of my tube audiophile friends would love. But for me, I am not fancy about it. I much prefer "life-like" sound to artificially sweetened sound. My taste is that a good sounding system would give me a feeling that a live performance is right in front of me.
I am hurried up to finish my active XO / EQ (hopefully tonight) so that I can listen to this completely "different" amp with my usual speakers to satisfy my curiosity.
Yes, the PSU of a tube preamp makes a huge difference in sound.
cm,
Which preamp from liteaudio you built sounds best? I mean more detailed, transparent, dynamic, clear, life-like? I guess most of them have a "vintage tubey" sound that sounds smooth, sweet but not necessarily life-like. Of course, I could be wrong.
Also, I have recently found they had a preamp using a single tube 12AX7 for a 2 stage - anode follower and cathode follower. This may not be a good amp but should be better than my Jarcar one, so before I finish building the 12B4A with a new PSU, I don't mind converting the Jarcar one to that one first. I have lately read a few tube amplifier tutorials and by now I should be able to experiment designing a simple one like that by myself. It would be a good learning experience too. But I am kind of lazy (and very busy) so I have not taken the challenge. If you have the schematic, please share it with me. That is the only schematic I am interested in because I have the 12AX7 on hand and I could do the mods in 20 minutes. I wouldn't build anything else as not to be distracted from building the 12B4A.
Regards,
Bill
I also heard that liteaudio uses LSDY to power up most of their tube preamps and has been selling completed products. They said they never had problems.
But in any case, I tried it, in replace of the cheap Jaycar one that coverts 12VDC to regulated 260VDC. In the process I also ditched the cathode bypass cap of the 12AX7.
Surprised, surprised, surprised! The sound was completely different from what it used to be. I mean it - completely different. I don't know if it is better or worse. I was used to my tower speaker of which the active XO is being rebuilt / fine-tuned so I could only use the BBC monitor Rogers Studio 1A for the test. I have not used the Rogers for sometime and I much prefer the sound of my tower speaker. For the preamp with the LSDY, some areas are substantially better and some areas much worse. How correct that Frank said that PSU gives 55% of the sound!
On the good side, "Presence" is superb! The sound is much more "fat" than thin, much more tubey, sounding thick, warm, rounded while maintaining good treble and bass. I had one such CD with a violin and a piano that sounded so good in the HiFi showroom when I bought my Rogers 10 years ago, but never sounded good on any other systems regardless of prices. This time after fitting in the LSDY that particular sound track sounded great! On the bad side, transparency and focus seem to be much worse (this could partly be due to using the Rogers rather than my tower speaker). This is the sound a few of my tube audiophile friends would love. But for me, I am not fancy about it. I much prefer "life-like" sound to artificially sweetened sound. My taste is that a good sounding system would give me a feeling that a live performance is right in front of me.
I am hurried up to finish my active XO / EQ (hopefully tonight) so that I can listen to this completely "different" amp with my usual speakers to satisfy my curiosity.
Yes, the PSU of a tube preamp makes a huge difference in sound.
cm,
Which preamp from liteaudio you built sounds best? I mean more detailed, transparent, dynamic, clear, life-like? I guess most of them have a "vintage tubey" sound that sounds smooth, sweet but not necessarily life-like. Of course, I could be wrong.
Also, I have recently found they had a preamp using a single tube 12AX7 for a 2 stage - anode follower and cathode follower. This may not be a good amp but should be better than my Jarcar one, so before I finish building the 12B4A with a new PSU, I don't mind converting the Jarcar one to that one first. I have lately read a few tube amplifier tutorials and by now I should be able to experiment designing a simple one like that by myself. It would be a good learning experience too. But I am kind of lazy (and very busy) so I have not taken the challenge. If you have the schematic, please share it with me. That is the only schematic I am interested in because I have the 12AX7 on hand and I could do the mods in 20 minutes. I wouldn't build anything else as not to be distracted from building the 12B4A.
Regards,
Bill
I like the LS12 the best. With a RCA 12AX7 and a Mullard ECC81, it is very lush, warm, and detailed. The LS9 is very detailed and have a good sound stage. Bass is full bodied but not punchy ( I used 6 Mullard ECC81 ) but mid range is lacking - not good for vocal. The LS7B is funadementally flawed in its design of the PS. You will kill your tubes. I had to do major modifications but after that is a good sound but colored - it is a matter of taste. My CD friends hated it but the vinyl group loves it. The LS26 is also colored but is it is lush and with smooth vocals. The sound is VERY dependent on hte 6DJ8 cathode follower at the output stage. I have tried Amperex 6DJ8, Mullard CV2492, Shuguang 6N11. Best balance sound was with Russian 6H23. The others - well nothing much to shout about. Hope I have answered your questions. I was in Guangzhou and got carried away buying too many kits. Their R core transformers are good quality and good value.
BTW, replace the two 47uF ecap on the B+ of the LSDY with oil motor run cap ( i used 22.5uF GE ), and you will hear a very significant improvement in details and sound stage. Much more airy, and musical instrements comes across more precisely.
An externally hosted image should be here but it was not working when we last tested it.
The above is what is in my mind for the first stage of the PSU. The transformer is rated at 280-0-280@150mA. Each 0-280 winding is used for one PSU for one channel. The above shows only one channel.
The second stage is a solid state CCS fed shunt regulator (either the SuperReg, or the one by Manfred Huber or the HPHV Shunt Reg v1.1) that will set 300V for the B+.
Here are my questions:
1. The above will have an output voltage before the CCS around 350V. Is 350V appropriate? I think I can easily adjust C1 to get a higher or lower voltage.
2. From PSUII I gathered the initial surge currents far exceeds the ratings for the transformer T1 (2A vs 150mA rating) and the choke L1 (1A vs 250mA rating). Would this be a problem? It is just for a short period of time of less than 0.2 seconds. Could I use 15H@100mA for the choke? It is much cheaper.
3. PSUII suggests the I(T1) RMS being 231mA. Why is it so high? Have I done anything wrong here? The 2 x 12B4A needs around 60mA so I thought 150mA rating for the transformer would be OK. Do I need to use 250mA rating for the transformer to be on the safe side?
4. For the shunt regulator, I can't find BSS135 and 2sk43-4 from anybody who don't impose "minimal order USD$300". Do you know of any substitutes?
CM, Thanks for your inputs in your last posts.
Cheers,
Bill
LSDY
Hi
I use LSDY too.
They work just fine (no chance to compare)
My problem is about the level of the output voltage.
How can I obtain 200V output?
If I change Zener from 130V to 100V, and using 100K/100K as the voltage divide resisters, the output will be 200V?
Hi
I use LSDY too.
They work just fine (no chance to compare)
My problem is about the level of the output voltage.
How can I obtain 200V output?
If I change Zener from 130V to 100V, and using 100K/100K as the voltage divide resisters, the output will be 200V?
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