CHokes
I'm not sure what the electroprint chokes rate at in terms of overload. My 20ma chokes are doing just fine, but they are from my maker in Hong Kong. I'm going to order some of his R-Core chokes (top quality), but if you want I can sell you the same chokes I'm using at my cost -- $14 per choke (if I remember correctly) + Shipping via flat rate USPS. When the R-Cores come, I'll let everyone know. It won't be until fall--shipping takes 12 weeks. Not sure what pricing will be as it depends on how much I buy and the current cost of copper. This last batch I bought was at the height of copper price hell.
IF you do go with EP, a DCR of around 2K is about right. Anything over 150H should work fine.
I'm not sure what the electroprint chokes rate at in terms of overload. My 20ma chokes are doing just fine, but they are from my maker in Hong Kong. I'm going to order some of his R-Core chokes (top quality), but if you want I can sell you the same chokes I'm using at my cost -- $14 per choke (if I remember correctly) + Shipping via flat rate USPS. When the R-Cores come, I'll let everyone know. It won't be until fall--shipping takes 12 weeks. Not sure what pricing will be as it depends on how much I buy and the current cost of copper. This last batch I bought was at the height of copper price hell.
IF you do go with EP, a DCR of around 2K is about right. Anything over 150H should work fine.
Finally getting traction on the KIT.
I've finally got a few things completed. Go to my new BLOG at http://audiovib.blogspot.com/ for details. Reworked the www.audiovib.net website--after teaching myself how to write menus. The site is much more user friendly now.
Got a new order coming from Hong Kong for the 12B4 kits and several others as well.
Next order of business is to compelte the BOM for the 12B4 amp and rework the web site for selling. I'm going to get it out as a basic kit, and work with a local craftsman to build a wooden case. He has a stock of old growth black walnut (among other woods) and is interested to try out some amp surrounds. His furniture designs were featured in shows a few years back-so he is good. Alternatively, you could install the kit in a Hammond box.
I do have one possible delay--I've found a source of local NOS tubes and parts: an entire basement full (to the rafters evidently) and I'm going to try bid on it. Hope it doesn't go out of my price range, I know some national dealers are sniffing around. If I win I'll be stocking and sorting for a few weeks.
I'll start posting updates on the BLOG regularly from now on.
tullskull said:
I've finally got a few things completed. Go to my new BLOG at http://audiovib.blogspot.com/ for details. Reworked the www.audiovib.net website--after teaching myself how to write menus. The site is much more user friendly now.
Got a new order coming from Hong Kong for the 12B4 kits and several others as well.
Next order of business is to compelte the BOM for the 12B4 amp and rework the web site for selling. I'm going to get it out as a basic kit, and work with a local craftsman to build a wooden case. He has a stock of old growth black walnut (among other woods) and is interested to try out some amp surrounds. His furniture designs were featured in shows a few years back-so he is good. Alternatively, you could install the kit in a Hammond box.
I do have one possible delay--I've found a source of local NOS tubes and parts: an entire basement full (to the rafters evidently) and I'm going to try bid on it. Hope it doesn't go out of my price range, I know some national dealers are sniffing around. If I win I'll be stocking and sorting for a few weeks.
I'll start posting updates on the BLOG regularly from now on.
12B4 + Phono Option
Phono Option underway.
I've started a new thread to continue and update all on KIT progress, NOS tubes, Phono, etc.
See:
http://www.diyaudio.com/forums/showthread.php?p=1897252#post1897252
Phono Option underway.
I've started a new thread to continue and update all on KIT progress, NOS tubes, Phono, etc.
See:
http://www.diyaudio.com/forums/showthread.php?p=1897252#post1897252
12B4 + Phono Option Link
Wrong Message link above. Sorry. Try this:
http://www.diyaudio.com/forums/showthread.php?p=1908496
Wrong Message link above. Sorry. Try this:
http://www.diyaudio.com/forums/showthread.php?p=1908496
12B4 Line Stage + Phono FINALLY POSTED!
Well it's up on my website now, only 2 months after I promised it:
http://www.audiovib.net/Designs/Audio/12B4/phonostage.htm
and the listening tests are posted on my Blog:
http://audiovib.blogspot.com/2009/09/12b4-line-12ax7-phono-stage-blind-test.html
And the specs for the Step-up transformers are posted at:
http://www.audiovib.com/Parts/Xfrmr&Chokes/PhonoStepUp71107A.htm
WHEW!
Haven't posted to the group for a while. Been sorting tubes! Bought another stash of about 1/2 million tubes. Why do I do these things to myself!!!
Got to start selling soon though, burnt through all my spare cash.
Cheers
Well it's up on my website now, only 2 months after I promised it:
http://www.audiovib.net/Designs/Audio/12B4/phonostage.htm
and the listening tests are posted on my Blog:
http://audiovib.blogspot.com/2009/09/12b4-line-12ax7-phono-stage-blind-test.html
And the specs for the Step-up transformers are posted at:
http://www.audiovib.com/Parts/Xfrmr&Chokes/PhonoStepUp71107A.htm
WHEW!
Haven't posted to the group for a while. Been sorting tubes! Bought another stash of about 1/2 million tubes. Why do I do these things to myself!!!
Got to start selling soon though, burnt through all my spare cash.
Cheers
12B4 Project
The project did not die. I've gone on to modify the line stage to accept either a 5687 or 12B4 as the driver tube and added a phono section with MM/MC options. You can see my (opinionated) testing results at my blog:
AudioVIB Labs.
I do have a quick note for those experiencing hum problems--I did find that a separate remote power supply may be required when using chokes. I could not get the hum to zero do to the chokes picking up magnetics in the case. The problem disappears with a resistor or SS active load.
One more interesting note--a resistor load that combines a paralleled carbon comp and metal film resistor has a sound signature remarkably close to a choke, but obviously lower gain.
I'm currently putting together a market prototype version that will be shown at CES in January.
The chokes are still for sale. I've got a few left, and I'm just getting ready to put in a new order. Send me an email via my website:
Audio VIBrations Sales and I'll send you a paypal invoice if you want.
On other fronts I'm starting a new community based on the concept of using neglected Old Stock tubes. I'd appreciate feedback. At this point I'm still working on the concept--see the thrust at: OSARA. I would like to start offering kits based on all types of tubes next year.
My latest 'star' output tube is 41/42/6F6 running in ultra-linear mode. This is truly a beautiful sounding tube in that configuration--much better than normal pentode mode, and it would fit right in with the OldStockAudio mission.
Cheers
The project did not die. I've gone on to modify the line stage to accept either a 5687 or 12B4 as the driver tube and added a phono section with MM/MC options. You can see my (opinionated) testing results at my blog:
AudioVIB Labs.
I do have a quick note for those experiencing hum problems--I did find that a separate remote power supply may be required when using chokes. I could not get the hum to zero do to the chokes picking up magnetics in the case. The problem disappears with a resistor or SS active load.
One more interesting note--a resistor load that combines a paralleled carbon comp and metal film resistor has a sound signature remarkably close to a choke, but obviously lower gain.
I'm currently putting together a market prototype version that will be shown at CES in January.
The chokes are still for sale. I've got a few left, and I'm just getting ready to put in a new order. Send me an email via my website:
Audio VIBrations Sales and I'll send you a paypal invoice if you want.
On other fronts I'm starting a new community based on the concept of using neglected Old Stock tubes. I'd appreciate feedback. At this point I'm still working on the concept--see the thrust at: OSARA. I would like to start offering kits based on all types of tubes next year.
My latest 'star' output tube is 41/42/6F6 running in ultra-linear mode. This is truly a beautiful sounding tube in that configuration--much better than normal pentode mode, and it would fit right in with the OldStockAudio mission.
Cheers
Choke option
Don't give up yet. I'm building a new prototype using a new Hammond transformer instead of a yard sale special. Old transformers can be a source of high magetic fields. I'll report the results in about a week.
Don't give up yet. I'm building a new prototype using a new Hammond transformer instead of a yard sale special. Old transformers can be a source of high magetic fields. I'll report the results in about a week.
That is normally correct. I'll check the chokes I have because I believe that is not true for them--I think they were wound so that the mutual inductance compensates for the loss, but I can't find my measurements and I'll have to redo it.
12B4 Kit design complete!
Dear Tube Mack and everyone else,
I have now completed prototype #2 of the the 12B4 line stage project, and with that the design is complete. Not surprisingly, it has grown. It now has a full blown phono MM/MC stage and the MC stage has selectable 10/20 db of gain.
Good news is I actually have a full BOM now, so I can build the kit and offer it. The remaining issue is still the case, but if any are interested in a caseless kit, let me know. I have enough stock parts to get a few out this year. I'll be meeting with the case builder on Saturday and I think that we can have a prototype design done before Christmas.
The options for this kit are going to be several, my recommendations are marked with (!):
- Tube or SS power supply
(!) 5V4 power tightens up midrange and brings extra clarity to the highs. Does add cost since a better transformer is needed to give DC filament supply.
- Tube regulation or not
(!) 0B3+0C3 for whole supply adds realism to the music and tightens bass. Very subtle, but still noticable.
- 12B4 or 5687 driver
(!) 5687 gives great gain for phono option, 12B4 great for line stage only.
- Choke or Resistor Anode load
(!) Choke is just plain better. All music sounds better--in all ranges.
- Phono
(!) Highly recommended. This is so much better sounding than my $8,000 Sterophile Class A SS reference phono amplifier. I am amazed at the realism.
- MC Phono option (adds step transformers).
(Good for up to .35mv cartridges)
- Phono gain tuning, phono rumble filter tuning.
- And of course the tube selection itself. Let your budget drive the choices.
The second generation separated the power supply from the amplifier. I highly(!) recommend this practice. It eliminates so many problems:
- No hum in Choke load
- Full shield for input phono stage not needed
- No fancy internal shielding required for switches or wire runs
- Easier construction
Only downside is a separate case and umbilical cable--but IMO that is small potatoes for the gain in performance.
I'll be posting design and pictures to my website soon-and notify group when done.
My prototype #1 will be available for sale soon if anyone is interested. Could use a little TLC on the inside--I have rewired it about 100 times (it seems like) trying out different options to get the best sound. In the spirit of full discovery the case is not pristine--I dropped it and put a slight dent in the back. I removed the choke option to eliminate hum, but added a CC versus Metal film resistor anode load option. The difference it very subtle, but there are times one is better than the other for a certain type of music. Still a very good line stage with a truly great phono MM/MC option. Currently has the 5687 option installed and the tube regulation removed. Can use a wide variety of tubes. I have a few hundred dollars in parts into it--and that is all I want out of it.
Merry Christmas to everyone!
Dear Tube Mack and everyone else,
I have now completed prototype #2 of the the 12B4 line stage project, and with that the design is complete. Not surprisingly, it has grown. It now has a full blown phono MM/MC stage and the MC stage has selectable 10/20 db of gain.
Good news is I actually have a full BOM now, so I can build the kit and offer it. The remaining issue is still the case, but if any are interested in a caseless kit, let me know. I have enough stock parts to get a few out this year. I'll be meeting with the case builder on Saturday and I think that we can have a prototype design done before Christmas.
The options for this kit are going to be several, my recommendations are marked with (!):
- Tube or SS power supply
(!) 5V4 power tightens up midrange and brings extra clarity to the highs. Does add cost since a better transformer is needed to give DC filament supply.
- Tube regulation or not
(!) 0B3+0C3 for whole supply adds realism to the music and tightens bass. Very subtle, but still noticable.
- 12B4 or 5687 driver
(!) 5687 gives great gain for phono option, 12B4 great for line stage only.
- Choke or Resistor Anode load
(!) Choke is just plain better. All music sounds better--in all ranges.
- Phono
(!) Highly recommended. This is so much better sounding than my $8,000 Sterophile Class A SS reference phono amplifier. I am amazed at the realism.
- MC Phono option (adds step transformers).
(Good for up to .35mv cartridges)
- Phono gain tuning, phono rumble filter tuning.
- And of course the tube selection itself. Let your budget drive the choices.
The second generation separated the power supply from the amplifier. I highly(!) recommend this practice. It eliminates so many problems:
- No hum in Choke load
- Full shield for input phono stage not needed
- No fancy internal shielding required for switches or wire runs
- Easier construction
Only downside is a separate case and umbilical cable--but IMO that is small potatoes for the gain in performance.
I'll be posting design and pictures to my website soon-and notify group when done.
My prototype #1 will be available for sale soon if anyone is interested. Could use a little TLC on the inside--I have rewired it about 100 times (it seems like) trying out different options to get the best sound. In the spirit of full discovery the case is not pristine--I dropped it and put a slight dent in the back. I removed the choke option to eliminate hum, but added a CC versus Metal film resistor anode load option. The difference it very subtle, but there are times one is better than the other for a certain type of music. Still a very good line stage with a truly great phono MM/MC option. Currently has the 5687 option installed and the tube regulation removed. Can use a wide variety of tubes. I have a few hundred dollars in parts into it--and that is all I want out of it.
Merry Christmas to everyone!
12B4 microphonics.
Nice design. I still prefer choke loads, but both active and choke sound better than resistor IMO--and of course the active reactivity goes away with chokes. It may just be, though, that I'm getting old and can't see IC leads as well so I prefer big components. http://www.diyaudio.com/forums/images/icons/icon7.gif.
Your point about 12B4 sensitivity is right on. They are sensitive to tapping, but not really microphonic. I think the microphonic problem is overblown on the 12B4. Just stay away from steel cases which can ring.
Nice design. I still prefer choke loads, but both active and choke sound better than resistor IMO--and of course the active reactivity goes away with chokes. It may just be, though, that I'm getting old and can't see IC leads as well so I prefer big components. http://www.diyaudio.com/forums/images/icons/icon7.gif.
Your point about 12B4 sensitivity is right on. They are sensitive to tapping, but not really microphonic. I think the microphonic problem is overblown on the 12B4. Just stay away from steel cases which can ring.
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