Hey Mach_Y,
Unuless you use only the ends without grounding the center tap, as in a bridge across the secondary, the 550-0-550 will only be 550 volts with the center tap grounded.
FYI,
Gabe
Unuless you use only the ends without grounding the center tap, as in a bridge across the secondary, the 550-0-550 will only be 550 volts with the center tap grounded.
FYI,
Gabe
Gabavee:
True... but I figured I would be charged for the higher rating... not the lower. That would drop the price in almost half it were true! 🙂
Thomas: you have email 🙂
True... but I figured I would be charged for the higher rating... not the lower. That would drop the price in almost half it were true! 🙂
Thomas: you have email 🙂
hi mach_y,
until, i still advise U use this chassis because the input, driver board had 4 set that u can use in 8,9 pin tubes Tranmsformer couples without change the others. The ground bar only within 1.5 feet is shory for quickly ground.
Also as I promise I will personal give U 1.5 feet 2mm thick 4N pure silver bar for U to use in the main ground. Pls give me a test report after compare with copper.
thanks
thomas
www.diyaudiocraft.com
until, i still advise U use this chassis because the input, driver board had 4 set that u can use in 8,9 pin tubes Tranmsformer couples without change the others. The ground bar only within 1.5 feet is shory for quickly ground.
Also as I promise I will personal give U 1.5 feet 2mm thick 4N pure silver bar for U to use in the main ground. Pls give me a test report after compare with copper.
thanks
thomas
www.diyaudiocraft.com
Attachments
Thomas:
I thought your chassis might have changeable parts 🙂 My only concern would be the capacitor mounts, as my design has 5 caps that mount above the board. Not to say that some of them could be located under the board though. Check your email, and don't forget to reply to me through the diyaudio email link.
Cdeveza:
I think I've found places where all those parts are sold, but the 6AU4GTA and 6AN4 I am having a hard time finding... what is your source of these?
I thought your chassis might have changeable parts 🙂 My only concern would be the capacitor mounts, as my design has 5 caps that mount above the board. Not to say that some of them could be located under the board though. Check your email, and don't forget to reply to me through the diyaudio email link.
Cdeveza:
I think I've found places where all those parts are sold, but the 6AU4GTA and 6AN4 I am having a hard time finding... what is your source of these?
Gabavee:
Don't worry about it at all! Any help is appreciated 🙂 It is has been a while since I've looked at schematics, so reminders are welcomed. Sorry if I came off otherwise.
I am still looking at the kit you sell actually... I've sent you an email about it.
Mark
Don't worry about it at all! Any help is appreciated 🙂 It is has been a while since I've looked at schematics, so reminders are welcomed. Sorry if I came off otherwise.
I am still looking at the kit you sell actually... I've sent you an email about it.
Mark
Mach_Y
Sorry about EP's website, anyway, if you have a chance to just call and talk to him, he can supply you these iron in two to three weeks. Jack is not much of a computer guy, he had somebody do his website, but I guess its gone now.
Anyway, you can get the ASC caps from Michael Percy,
http://www.percyaudio.com/
You can use GE caps, but it has to be Polypropylenes AC Caps. Also, you can use between 60uf to 90uf and you can use 370vac instead of 440vac, it does not have to be exactly 70uf as the original schematic says, as you can see, I am using an ASC 60uf and a 22uf GE connected in parallel, I ran it with just the 60uf and it sounded ok, I just had the 22uf on hand so I thought I will just throw that in.
Sorry about EP's website, anyway, if you have a chance to just call and talk to him, he can supply you these iron in two to three weeks. Jack is not much of a computer guy, he had somebody do his website, but I guess its gone now.
Anyway, you can get the ASC caps from Michael Percy,
http://www.percyaudio.com/
You can use GE caps, but it has to be Polypropylenes AC Caps. Also, you can use between 60uf to 90uf and you can use 370vac instead of 440vac, it does not have to be exactly 70uf as the original schematic says, as you can see, I am using an ASC 60uf and a 22uf GE connected in parallel, I ran it with just the 60uf and it sounded ok, I just had the 22uf on hand so I thought I will just throw that in.
Bas Wrote:
How necessary or important do you find the rheostats?
Why not just find out what the right values are..and solder them in place?
Regards,
Bas
The rheostat or an adjustable resistor as substitute is used here to adjust for tubes deviations from published specs, in other words, no two tubes are alike, and any shift in operating point will affect the next stage as the driver stage is directly connected to the 300B grid. The driver plate voltage is the bias voltage of the 300B. Any slight deviation on the driver can have a significant effect on the 300B. I guess you can just find the right values and just replace the rheostat with fixed resistors, but you are limiting yourself on the amps ability to operate at different operating points.
With the rheostat, I can adjust the amp to ran the 300b at 450v/5ma and 390v/89ma or any combination as long as I do not exceed the 40w plate dissipation limit, and listen to it, if there are any difference in sound.
So I guess, yes you can replace the rheostat with fixed resistor, but you limit your flexibility to optimize your amp to ran at its maximum for the current driver and power tube you are using.
Alex Deveza
How necessary or important do you find the rheostats?
Why not just find out what the right values are..and solder them in place?
Regards,
Bas
The rheostat or an adjustable resistor as substitute is used here to adjust for tubes deviations from published specs, in other words, no two tubes are alike, and any shift in operating point will affect the next stage as the driver stage is directly connected to the 300B grid. The driver plate voltage is the bias voltage of the 300B. Any slight deviation on the driver can have a significant effect on the 300B. I guess you can just find the right values and just replace the rheostat with fixed resistors, but you are limiting yourself on the amps ability to operate at different operating points.
With the rheostat, I can adjust the amp to ran the 300b at 450v/5ma and 390v/89ma or any combination as long as I do not exceed the 40w plate dissipation limit, and listen to it, if there are any difference in sound.
So I guess, yes you can replace the rheostat with fixed resistor, but you limit your flexibility to optimize your amp to ran at its maximum for the current driver and power tube you are using.
Alex Deveza
cdeveza said:
Alex, thanks for the response. I'll try to call him, but it is next to impossible being I am deployed in the desert right now 🙁
In regards to your post about the rheostats, is there any problem with putting a display in the schematic permananetly? I was thinking of using the sophia 100ma round meter, one in each monoblock, to check the plate dissipation (is that the right term?) on the 300b. I'm looking into some kind of voltage display as well. Would it be better to have a switch for them?
Thanks!
Mach_Y
I ran across this idea before, chris of the Randall Museum is actually thinking about it too. As for me, this is how I look at it, first, knowing the current (Plate dissipation by the way, is the product of the current flowing into the tube and the voltage across the tube, the voltage measured between the place and the cathode) is only half the importation you need, as it is the plate dissipation that is important, you therefore need the voltage across the tube also, hence your suggestion on putting a means of measuring voltage, but then when you get all this hooked up, it can interfere with the proper operation of the circuit, hence again, your suggestion of putting a switch, then it actually contradicts your original motive of monitoring the current and voltage. So I said to myself, I will just go the siimpliest route, after all, why make a very good simple circuit complex. So here is what I did, I simply put a 10 Ohm/10watt resistor at the cathode. So to check for current, I measure the voltage across this resistor, 1 volt reading means 100ma, .86 volt is 86ma. Yes it is not convenient to do this as you have to do it from underneath, but how many times do you really have to do this. So my suggestion is save your money for a BlackGate cathode cap, this contributes directly to the quality of sound your amp will produce.
As for the sound of this amp, you asked. I will tell you based on what I have observed so far and maybe compared to other amps. This amp is a very Honest amp, other amp that has a cap in the signal path, introduces some time delays, this gives it some character, you may hear other people say, syrupy sound. Sometimes those amps may sound very wide due to its time delay on some frequencies, well, the DRD amp does not have this as it has no cap in the signal path. What this amp deliver however, I guess due to its Ultra-Path design(thats the big 40uf connected between the B+ and the 300B cathode), is its extreme ability to extract detail from your musical sources, its clarity is stunning, again be prepared as this no bull, this amp will deliver. You MUST have good high efficiency speaker to go with it however, or all this is for nothing. I am running a pair of Hammer Dynamics with it and loving it.
I have been meaning to say something to you about your being there and putting you life on the line so that we here can built all this lovely amps, but I just could not find the words, so I would like just to say that I personally support you and everyones effort there. I used to be in the Navy, 25 years ago, and I know how it feels. So If you have a chance to pass by the San Francisco area, look me up and I will help you build more amp toys. Thats the least I can do for our heroes.
BTW, just a suggestion, why dont you wait and call Jack when you get home, it does not take long for him to ship those iron to you, since he normally have them on stock. He is really a pleasant guy to talk to, you will learn a lot from him, you can ask him questions about amp design and building and he will gladly help you out. He based his amp design knowledge from experience, not on formal education, he is truly a creative guy, he is a musician, a painter, an inventor, he's got some patent on something he invented, dont know what, but hes got one, I think thats where he got the comapany name Electra-Print. This name does not even relate to anything Transformer. He used to work as a recording engineer somewhere. He is a very interesting guy to talk to. I highly recommend you call and talk to him when you get back, even if you are not going to buy anything, just talk amp building and he will entertain you.
Alex Deveza
I ran across this idea before, chris of the Randall Museum is actually thinking about it too. As for me, this is how I look at it, first, knowing the current (Plate dissipation by the way, is the product of the current flowing into the tube and the voltage across the tube, the voltage measured between the place and the cathode) is only half the importation you need, as it is the plate dissipation that is important, you therefore need the voltage across the tube also, hence your suggestion on putting a means of measuring voltage, but then when you get all this hooked up, it can interfere with the proper operation of the circuit, hence again, your suggestion of putting a switch, then it actually contradicts your original motive of monitoring the current and voltage. So I said to myself, I will just go the siimpliest route, after all, why make a very good simple circuit complex. So here is what I did, I simply put a 10 Ohm/10watt resistor at the cathode. So to check for current, I measure the voltage across this resistor, 1 volt reading means 100ma, .86 volt is 86ma. Yes it is not convenient to do this as you have to do it from underneath, but how many times do you really have to do this. So my suggestion is save your money for a BlackGate cathode cap, this contributes directly to the quality of sound your amp will produce.
As for the sound of this amp, you asked. I will tell you based on what I have observed so far and maybe compared to other amps. This amp is a very Honest amp, other amp that has a cap in the signal path, introduces some time delays, this gives it some character, you may hear other people say, syrupy sound. Sometimes those amps may sound very wide due to its time delay on some frequencies, well, the DRD amp does not have this as it has no cap in the signal path. What this amp deliver however, I guess due to its Ultra-Path design(thats the big 40uf connected between the B+ and the 300B cathode), is its extreme ability to extract detail from your musical sources, its clarity is stunning, again be prepared as this no bull, this amp will deliver. You MUST have good high efficiency speaker to go with it however, or all this is for nothing. I am running a pair of Hammer Dynamics with it and loving it.
I have been meaning to say something to you about your being there and putting you life on the line so that we here can built all this lovely amps, but I just could not find the words, so I would like just to say that I personally support you and everyones effort there. I used to be in the Navy, 25 years ago, and I know how it feels. So If you have a chance to pass by the San Francisco area, look me up and I will help you build more amp toys. Thats the least I can do for our heroes.
BTW, just a suggestion, why dont you wait and call Jack when you get home, it does not take long for him to ship those iron to you, since he normally have them on stock. He is really a pleasant guy to talk to, you will learn a lot from him, you can ask him questions about amp design and building and he will gladly help you out. He based his amp design knowledge from experience, not on formal education, he is truly a creative guy, he is a musician, a painter, an inventor, he's got some patent on something he invented, dont know what, but hes got one, I think thats where he got the comapany name Electra-Print. This name does not even relate to anything Transformer. He used to work as a recording engineer somewhere. He is a very interesting guy to talk to. I highly recommend you call and talk to him when you get back, even if you are not going to buy anything, just talk amp building and he will entertain you.
Alex Deveza
hi,
I hope this was not my misunderstanding.
This is a very good method to less lose the triode high & detail freq air.
But, Unless U will not change the 300b tube. Otherwise U must did many time & solder many times.
There was one method will be better.
for example 2.5~0~2.5
THE POWER TRANS FILAMENT SECTION MUST TWIST WIRE & PARALLEL WIREWOUND.
THAN USE THIS METHOD TO CONNECT.
we use 2.5 & 2.5 ( head & tail to connect to the 300b's filament & the 0V connect TO THE CATHODE RESISTERS & CATHODE CAPACITORS. THEN DIRECTLY TO GROUND IS ok, not need to use any hum balance.
This method was use the power trans Ground to balance the 300b's filament but not need any hum balance.
This is the best but the power trans must very very good. & use above mthod to wound. No any wire wound resister will eat the high & detail air.
I hope my english is not good But U will understand.
thanks
Thomas
I hope this was not my misunderstanding.
This is a very good method to less lose the triode high & detail freq air.
But, Unless U will not change the 300b tube. Otherwise U must did many time & solder many times.
There was one method will be better.
for example 2.5~0~2.5
THE POWER TRANS FILAMENT SECTION MUST TWIST WIRE & PARALLEL WIREWOUND.
THAN USE THIS METHOD TO CONNECT.
we use 2.5 & 2.5 ( head & tail to connect to the 300b's filament & the 0V connect TO THE CATHODE RESISTERS & CATHODE CAPACITORS. THEN DIRECTLY TO GROUND IS ok, not need to use any hum balance.
This method was use the power trans Ground to balance the 300b's filament but not need any hum balance.
This is the best but the power trans must very very good. & use above mthod to wound. No any wire wound resister will eat the high & detail air.
I hope my english is not good But U will understand.
thanks
Thomas
Thomas,
I hope I understand you correctly. The resistor he was mentioning about is NOT for hum balance, it is a voltage divider network to supply B+ to the driver.
I suggest everyone looking at the schematic to look at this area as this is where it is tricky. Most people that has adjustable bias, meaning a resistor at the cathode, think that the voltage at the cathode reference to ground is the bias, NOT so in this amp, the bias is the voltage difference between the cathode and the 300b grid. Since the grid (on my schematic) is 185v and the cathode is 270v reference to ground, the effective bias would be 85volts at 450v, the voltage across the tube. So to get the proper operating point, you have to play around with BOTH rheostat to get the correct voltages.
You may not get the exact voltage values, but as long as the 300B does not exceed the rated plate dissipation of 40w and the 6AN4 does not exceed the rated dissipation of 4w, then that is a start. My actual measurement on my amp are: 710v at the 300B plate, 200v at the 300B grid, 1.2v at 6AN4 cathode, about 287v at 300B cathode.
Alex Deveza
I hope I understand you correctly. The resistor he was mentioning about is NOT for hum balance, it is a voltage divider network to supply B+ to the driver.
I suggest everyone looking at the schematic to look at this area as this is where it is tricky. Most people that has adjustable bias, meaning a resistor at the cathode, think that the voltage at the cathode reference to ground is the bias, NOT so in this amp, the bias is the voltage difference between the cathode and the 300b grid. Since the grid (on my schematic) is 185v and the cathode is 270v reference to ground, the effective bias would be 85volts at 450v, the voltage across the tube. So to get the proper operating point, you have to play around with BOTH rheostat to get the correct voltages.
You may not get the exact voltage values, but as long as the 300B does not exceed the rated plate dissipation of 40w and the 6AN4 does not exceed the rated dissipation of 4w, then that is a start. My actual measurement on my amp are: 710v at the 300B plate, 200v at the 300B grid, 1.2v at 6AN4 cathode, about 287v at 300B cathode.
Alex Deveza
cdeveza said:
Alex,
Thanks 🙂 Here is an excel spreadsheet zipped that shows the parts list, place to buy, and prices, including total price for mono or stereo chassis. The only parts that I see I could upgrade would be the output transformers (to EP), the 300b tubes, and the power supply caps to blackgates. Other than those I tried to go just about all out. For the $17.50 for the sophia 100ma displays, I figured it's worth it. This way I can see if the power tubes shift over time. My question is where to connect it to the circuit.
On the same track, what program did you use to make your schematic? Any chance you could send me the schematic file and a link to the program so I can mess around with it myself? Thanks 🙂
Mark
Alex,
It is interesting you mention that you use Hammer Dynamics speakers 🙂 I am looking into what speakers I want to use with these... right now I have a built pair of "the bang!" 94db speakers I can use for the time being. I was considering a pair of the Moth Audio Cicada's, but had looked at Hammer Dynamics, as well as building my own 100db speakers with a ESg3 pure ribbon tweeter and PHL3451 midrange. Any comments on your Hammer Dynamics? Have you done any of the mods to them?
Mark
It is interesting you mention that you use Hammer Dynamics speakers 🙂 I am looking into what speakers I want to use with these... right now I have a built pair of "the bang!" 94db speakers I can use for the time being. I was considering a pair of the Moth Audio Cicada's, but had looked at Hammer Dynamics, as well as building my own 100db speakers with a ESg3 pure ribbon tweeter and PHL3451 midrange. Any comments on your Hammer Dynamics? Have you done any of the mods to them?
Mark
SPEAKER Q.
Hi,
If you go 300B SE and like the efficiency of full-range speakers than the likes of Hammer, Supravox, Fertin and I forget some will certainly appeal to you.
When less is more than a X-overless FR speaker is most certainly more especially when you go OB.
Just pick one that sounds natural to you, something I can't say about the Lowthers I heard I regret to say.
Cheers,😉
Hi,
If you go 300B SE and like the efficiency of full-range speakers than the likes of Hammer, Supravox, Fertin and I forget some will certainly appeal to you.
When less is more than a X-overless FR speaker is most certainly more especially when you go OB.
Just pick one that sounds natural to you, something I can't say about the Lowthers I heard I regret to say.
Cheers,😉
Fdegrove: supposedly the moth audio cicada driver fixes the unpleasantness that plagues lowther drivers... although I have personally never heard either 🙁
MOTH.
Hi,
No idea how they managed that feat, haven't heard the Moth Cicada either.
Other ways around it are coating the membrane, tricky business that is though.
The Belgian importer happens to be a very good friend of mine and these colourations I hear in his very expensive systems don't seem to bother him all that much...if at all.
To my ears that honky sound is killing my listening pleasure...I need to find a diplomatic way to get the message across though.🙄
Cheers, 😉
Hi,
No idea how they managed that feat, haven't heard the Moth Cicada either.
Other ways around it are coating the membrane, tricky business that is though.
The Belgian importer happens to be a very good friend of mine and these colourations I hear in his very expensive systems don't seem to bother him all that much...if at all.
To my ears that honky sound is killing my listening pleasure...I need to find a diplomatic way to get the message across though.🙄
Cheers, 😉
Re: MOTH.
Just the reviews I have read say that the moth audio driver got rid of the midrange peak that causes that "honkiness" associated with lowther drivers. One of the reasons I am leaning more toward the Hammer Dynamics set... but the moth audio cicada drivers are only $125 each... makes for a cheap 94db efficient setup to see what full range drivers are all about 🙂
fdegrove said:
Just the reviews I have read say that the moth audio driver got rid of the midrange peak that causes that "honkiness" associated with lowther drivers. One of the reasons I am leaning more toward the Hammer Dynamics set... but the moth audio cicada drivers are only $125 each... makes for a cheap 94db efficient setup to see what full range drivers are all about 🙂
cdeveza said:
Cdeveza: In the picture you posted on the underneath of your amp, it looks like you have a resistor in parallel with the 2 ASC oil caps (I assume as a bleeder). What value did you use here?
Also, in your resistor / rheostat section... if I don't use the 10ohm/10watt resistor, I can use that money on the Sophia 100ma display 🙂 My question is where to hook it up... unless my mind is leaving me, it needs to be inline with the juice. Voltage you can just measure at whatever points you are interested in, but for amperage you have to break the circuit... correct? I emailed sophiaelectronics to ask them how their display needs to be hooked up.
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