Interesting modification to the ET 2. I get where shooter is coming from. The ET 2 system usually has a much longer tonearm and also the counterweight assembly is attached to the arm with a spring and some damping pads. Where the counterweight is placed affects arm resonance. Not sure how this shortened arm impacts all of that.
The counterweight and overall configuration are not done yet.
The spring mechanism of the original was something I never thought much of. I have the original ET-1 and its rigid counterweight stem had much better bass response than the ET-2.
A talk with AJ Conti of Basis TT,s before his passing, mentioned this off the cuff while in converstion and found it to be accurate and matched my experience with both.
Besides the silicone trough drops all resonant peaks below 20 hz by at least 40% according to ET, plus since I have reduced the arm length 4" the leverage ratio to spring CW is now off, so this is new territory anyway I think..,
The spring thing would benefit high compliance carts more than low IMO
Mounting is the issue since its over 12" in length and has to mount completely different than the original, and that requires a new plinth design....,
Please remember this is about Kevin,s SG system and I don,t wish to derail it and have already said too much. PM me if you wish instead.
Phase- Kevin
Now I see what is really going on with the internal circuit description and it makes total sense now , thanx
This is not your mothers LOMC !
Regards
David
The spring mechanism of the original was something I never thought much of. I have the original ET-1 and its rigid counterweight stem had much better bass response than the ET-2.
A talk with AJ Conti of Basis TT,s before his passing, mentioned this off the cuff while in converstion and found it to be accurate and matched my experience with both.
Besides the silicone trough drops all resonant peaks below 20 hz by at least 40% according to ET, plus since I have reduced the arm length 4" the leverage ratio to spring CW is now off, so this is new territory anyway I think..,
The spring thing would benefit high compliance carts more than low IMO
Mounting is the issue since its over 12" in length and has to mount completely different than the original, and that requires a new plinth design....,
Please remember this is about Kevin,s SG system and I don,t wish to derail it and have already said too much. PM me if you wish instead.
Phase- Kevin
Now I see what is really going on with the internal circuit description and it makes total sense now , thanx
This is not your mothers LOMC !
Regards
David
I don't mind the diversion since it does relate to an implementation using one of these cartridges.
To elaborate on Shooter's and GTHICM's comments I was wondering about VTA - I've found these cartridges in particular when equipped with the Shibata to be quite sensitive to VTA, which given the short distance to the pivot on the Souther is something I have to be aware of. There is a narrow window where it is rather good, which seems to encompass the range required for the thickness of the records I have, but not much beyond that.
To elaborate on Shooter's and GTHICM's comments I was wondering about VTA - I've found these cartridges in particular when equipped with the Shibata to be quite sensitive to VTA, which given the short distance to the pivot on the Souther is something I have to be aware of. There is a narrow window where it is rather good, which seems to encompass the range required for the thickness of the records I have, but not much beyond that.
When you think of a conventional 12" tonearm, it takes just over 5 mm of base height to change SRA ( stylus rake angle ) 1 degree and a 10" about 4mm.
Now pull down to 3 or 2" in tonearm length and the VTA arm change has magnified the dimensional relationship.
Thats why you need a vacuum platter to minimize any warps at these dimensions and even small VTA make a sonic difference. Welcome to the party..
A hyper-eliptical profile would probably work best but then again at these prices on removable tips whos complaining!
Regards
David
Now pull down to 3 or 2" in tonearm length and the VTA arm change has magnified the dimensional relationship.
Thats why you need a vacuum platter to minimize any warps at these dimensions and even small VTA make a sonic difference. Welcome to the party..
A hyper-eliptical profile would probably work best but then again at these prices on removable tips whos complaining!
Regards
David
Transformers will be Heyboer and will incorporate electrostatic shielding, and copper belly band. End bells will be black. Approximate rating 60VA. 3 secondaries are provided..
250V @ 80 - 100mA (target 340Vdc @ 50mA, bridge 100uF)
24V @ 100mA (target 33Vdc @ 20mA, bridge 2200uF)
8.0V @ 3A (target 11Vdc @ 1.6A, bridge 10000uF)
120V nominal primary. (Values given are at nominal line voltage, not minimums.)
I am expecting the dimensional information in the next couple of days.
Total cost for the power transformer I estimate at $75. Estimated lead time on the transformers is 4 weeks.
Total cost of one set of boards is $40.00 (That is two phono boards and one PSU board)
Total for boards and transformer per set comes to approximately $115. Prices do not include shipping.
I can ship boards and transformers separately or together as people prefer. The boards should be ready to ship around 7/30..
I will contact by email when I have the firm price, and will offer appropriate shipping option at that time.
250V @ 80 - 100mA (target 340Vdc @ 50mA, bridge 100uF)
24V @ 100mA (target 33Vdc @ 20mA, bridge 2200uF)
8.0V @ 3A (target 11Vdc @ 1.6A, bridge 10000uF)
120V nominal primary. (Values given are at nominal line voltage, not minimums.)
I am expecting the dimensional information in the next couple of days.
Total cost for the power transformer I estimate at $75. Estimated lead time on the transformers is 4 weeks.
Total cost of one set of boards is $40.00 (That is two phono boards and one PSU board)
Total for boards and transformer per set comes to approximately $115. Prices do not include shipping.
I can ship boards and transformers separately or together as people prefer. The boards should be ready to ship around 7/30..
I will contact by email when I have the firm price, and will offer appropriate shipping option at that time.
Well the new boards arrived today and they look good. I have almost completed the assembly of my pair, but due to parts shortages will have to wait for a few parts to get here.
Expect emails in the following days with instructions for payment and 2 options for shipping, except for international participants who basically get one choice due to the much higher costs. Basically some may want their boards in the weeks before the power transformers are available, others may want to save a few $$ on shipping and wait for me to ship everything.
Here are some shots of me assembling my set of 2nd gen boards.
You may want to start to order some parts.
For the SMD resistors used for grid stoppers, and in various other places 0.25W 1% 100PPM thinfilm 1206 SMD (not the wide ones!) from Stackpole, Vishay, Panasonic or similar are all fine.
For the RN60 size resistors I recommend PRP, Holco or Roederstein (mostly vintage) I assume Dale Vishays will work as well; 1% 100PPM resistors are fine.
Ah, capacitors... The results will be commensurate with the quality of the parts you use, even more so than the resistors. You've not heard me say this before here, but it matters... A lot.
REL RTX are pretty cheap and will work quite well. The 100V and 400V parts will fit on the board. Matching is not a bad idea.
The output cap I like is a TRT Dynamicap, and it's a bit expensive. Possibly one of the better Clarity Caps is a saner choice.
The 120pF cap ideally would be a Siemens if you can get it. TRW OK too, Mial in a pinch. Not made any more. Avoid Russian Mica, which probably won't fit.
Sockets, Amphenol NOS US made will fit as will a whole bunch of current production you can find readily on eBay.
Buy good ones..
Take your time. Install all SMD parts first. Do the LSK389 first with ESD precautions. Install the sockets only after all of the SMD parts in place it will be harder. I install most of the resistors, particularly those close to sockets before I install the sockets.
C4 and C5 should be the very LAST things you install after the heat sink and Q3 and Q4
I recommend the Ohmite heat sinks, they come in 1.5", 2.0" and 2.5" lengths.
EA-T220-38E Ohmite | Fans, Thermal Management | DigiKey
EA-T220-51E Ohmite | Fans, Thermal Management | DigiKey
EA-T220-64E Ohmite | Fans, Thermal Management | DigiKey
The 2.5" heat sink is suitable for use with the filament regulator, and the HV regulators on the PSU card.
Gentlemen, start warming up your solder irons..
Expect emails in the following days with instructions for payment and 2 options for shipping, except for international participants who basically get one choice due to the much higher costs. Basically some may want their boards in the weeks before the power transformers are available, others may want to save a few $$ on shipping and wait for me to ship everything.
Here are some shots of me assembling my set of 2nd gen boards.
You may want to start to order some parts.
For the SMD resistors used for grid stoppers, and in various other places 0.25W 1% 100PPM thinfilm 1206 SMD (not the wide ones!) from Stackpole, Vishay, Panasonic or similar are all fine.
For the RN60 size resistors I recommend PRP, Holco or Roederstein (mostly vintage) I assume Dale Vishays will work as well; 1% 100PPM resistors are fine.
Ah, capacitors... The results will be commensurate with the quality of the parts you use, even more so than the resistors. You've not heard me say this before here, but it matters... A lot.
REL RTX are pretty cheap and will work quite well. The 100V and 400V parts will fit on the board. Matching is not a bad idea.
The output cap I like is a TRT Dynamicap, and it's a bit expensive. Possibly one of the better Clarity Caps is a saner choice.
The 120pF cap ideally would be a Siemens if you can get it. TRW OK too, Mial in a pinch. Not made any more. Avoid Russian Mica, which probably won't fit.
Sockets, Amphenol NOS US made will fit as will a whole bunch of current production you can find readily on eBay.
Buy good ones..
Take your time. Install all SMD parts first. Do the LSK389 first with ESD precautions. Install the sockets only after all of the SMD parts in place it will be harder. I install most of the resistors, particularly those close to sockets before I install the sockets.
C4 and C5 should be the very LAST things you install after the heat sink and Q3 and Q4
I recommend the Ohmite heat sinks, they come in 1.5", 2.0" and 2.5" lengths.
EA-T220-38E Ohmite | Fans, Thermal Management | DigiKey
EA-T220-51E Ohmite | Fans, Thermal Management | DigiKey
EA-T220-64E Ohmite | Fans, Thermal Management | DigiKey
The 2.5" heat sink is suitable for use with the filament regulator, and the HV regulators on the PSU card.
Gentlemen, start warming up your solder irons..
Attachments
Here is an update. I completed the rev.2.1 strain gauge boards tonight, and now like everyone else need to wait for my transformer.. LOL
Went together nicely and everything fit. The quality of the boards is very good and solderability is excellent.
Next is acquisition of chassis for the power supply and audio section. I still have not seen the specification/drawing for the transformer so final PSU chassis design will have wait for that detail
Here are a couple of shots of the audio boards and power supply board.
Went together nicely and everything fit. The quality of the boards is very good and solderability is excellent.
Next is acquisition of chassis for the power supply and audio section. I still have not seen the specification/drawing for the transformer so final PSU chassis design will have wait for that detail
Here are a couple of shots of the audio boards and power supply board.
Attachments
Shipping Shooter's and AVWERK's boards by priority mail today.
I am still awaiting schedule information from Heyboer, but based on what I know they are still on schedule. I expect to be shipping power transformers in late August.
I also want to thank everyone for paying so promptly. I have a lot of money tied up in boards and transformers, so this frankly is a bit of a relief. I didn't pass along any of the development costs so this really helps me to stay in good with my CFO..
I am still awaiting schedule information from Heyboer, but based on what I know they are still on schedule. I expect to be shipping power transformers in late August.
I also want to thank everyone for paying so promptly. I have a lot of money tied up in boards and transformers, so this frankly is a bit of a relief. I didn't pass along any of the development costs so this really helps me to stay in good with my CFO..
Shipping Virtuono's boards today.
Waiting on Heyboer transformers, the balance will all ship via USPS Priority Mail once they get here. I will advise as I know more.
I am working with Landfall for a set of chassis for mine. They are in the process of relocating and will not be able to make my chassis until early fall. Once I have them I will of course share all the details.. Their chassis are great so for me it is worth the wait.
I recommend that the PSU be housed separately from the audio portion of the pre-amp to eliminate the possibility of both magnetic and electrostatic coupling between the PSU and the audio section.
I also recommend that they be fully enclosed in metal boxes to reduce the possibility of external interference.
Waiting on Heyboer transformers, the balance will all ship via USPS Priority Mail once they get here. I will advise as I know more.
I am working with Landfall for a set of chassis for mine. They are in the process of relocating and will not be able to make my chassis until early fall. Once I have them I will of course share all the details..
Their chassis are great so for me it is worth the wait.I recommend that the PSU be housed separately from the audio portion of the pre-amp to eliminate the possibility of both magnetic and electrostatic coupling between the PSU and the audio section.
I also recommend that they be fully enclosed in metal boxes to reduce the possibility of external interference.
I was very pleased with the quality of the boards, these are made by PCBCart - highly recommended. My neophyte lay out skills are improving.
Just be sure to solder it the right way around. Practice with some cheap SOIC op-amps if you need to.
What I did:
Use .032" eutectic solder or smaller
small conical tip works for me. (Hot! 700 degrees F - quick)
Apply solder to just one pad - I usually choose pin 1 or 8.
Using SMD tweezers place line up the chip on its footprint. Heat lead and pad until solder flows.
Solder all other pins. (You can do one single blob and use small solder wick to remove just some of the solder)
Do not over heat!
I recommend soldering all SMD components before any TH parts
Good luck, take your time..
Just be sure to solder it the right way around.
Practice with some cheap SOIC op-amps if you need to.What I did:
Use .032" eutectic solder or smaller
small conical tip works for me. (Hot! 700 degrees F - quick)
Apply solder to just one pad - I usually choose pin 1 or 8.
Using SMD tweezers place line up the chip on its footprint. Heat lead and pad until solder flows.
Solder all other pins. (You can do one single blob and use small solder wick to remove just some of the solder)
Do not over heat!
I recommend soldering all SMD components before any TH parts
Good luck, take your time..
I was very pleased with the quality of the boards, these are made by PCBCart - highly recommended. My neophyte lay out skills are improving.
Just be sure to solder it the right way around.
What I did:
Use .032" eutectic solder or smaller
small conical tip works for me. (Hot! 700 degrees F - quick)
Apply solder to just one pad - I usually choose pin 1 or 8.
Using SMD tweezers place line up the chip on its footprint. Heat lead and pad until solder flows.
Solder all other pins. (You can do one single blob and use small solder wick to remove just some of the solder)
Do not over heat!
I recommend soldering all SMD components before any TH parts
Good luck, take your time..
Kevin, any particular reason for using surface mount components?
John
Often a matter of personal preference and it is also the case that in the real, non-audiophile world where I spend most of my days engineering, TH parts except in a limited number of instances are completely obsolete, and good ones require scrounging. (Bear in mind that this wasn't originally designed for general consumption, I had no intention of offering the boards, so the design catered to my preferences specifically. I was caught off guard by the level of interest.)
In some cases it allows me to place things like grid or gate stopper resistors closer to where they help.
No lead parasitics and none of the resistive element termination issues sometimes encountered with through hole resistors.
They are much cheaper so I tend to use them where exotic parts are not required, and when I place parts on both sides of the board. (There are a few on this board, but not many)
Provides me with greater choice in components. Thin film SMD resistors made by well respected first line manufacturers may perform better in some cases than much more expensive boutique parts made by 2nd or 3rd tier makers. Sadly suitable SMD parts are available from many sources, which is no longer the case for some of the better through hole parts I used putting mine together.
The TH version of the LSK389 will probably disappear at some point, hence the choice of SOIC, without that part a significant aspect of the design is no longer available.
In the case of the LR8 series regulator there is no TH part I was comfortable using, hence the DPAK package.
With the exception of the grid stopper resistors there are no SMD resistors directly in the signal path.
I chose 1206 resistors which are big enough to be easily placed by the 60yr old designer. The biggest challenge is the SOIC and that's not bad.
And I like challenges..
In some cases it allows me to place things like grid or gate stopper resistors closer to where they help.
No lead parasitics and none of the resistive element termination issues sometimes encountered with through hole resistors.
They are much cheaper so I tend to use them where exotic parts are not required, and when I place parts on both sides of the board. (There are a few on this board, but not many)
Provides me with greater choice in components. Thin film SMD resistors made by well respected first line manufacturers may perform better in some cases than much more expensive boutique parts made by 2nd or 3rd tier makers. Sadly suitable SMD parts are available from many sources, which is no longer the case for some of the better through hole parts I used putting mine together.
The TH version of the LSK389 will probably disappear at some point, hence the choice of SOIC, without that part a significant aspect of the design is no longer available.
In the case of the LR8 series regulator there is no TH part I was comfortable using, hence the DPAK package.
With the exception of the grid stopper resistors there are no SMD resistors directly in the signal path.
I chose 1206 resistors which are big enough to be easily placed by the 60yr old designer. The biggest challenge is the SOIC and that's not bad.
And I like challenges..
Hi Kevin
I think I am late for the party. It is very interesting project. How difficult to find a strain gauge cartridge? I guess it is too late to join the group. What is the total cost of this project? I can solder but I am not good at measuring and adjusting once I finish soldering the board. Are there any measuring and adjusting involved? How about compliance for strain gauge cartridge if it is still applicable.
Hi David
I definitely think you should start a new thread so we all can learn from your air bearing arm project.
Jim
I think I am late for the party. It is very interesting project. How difficult to find a strain gauge cartridge? I guess it is too late to join the group. What is the total cost of this project? I can solder but I am not good at measuring and adjusting once I finish soldering the board. Are there any measuring and adjusting involved? How about compliance for strain gauge cartridge if it is still applicable.
Hi David
I definitely think you should start a new thread so we all can learn from your air bearing arm project.
Jim