Member
Joined 2002
BrianDonegan said:
Ill send you a picture tonight and model numbers. Do you have a test one of these i can sample if i like ill buy one . ?
Hmm, a piece of telecom equpt. I work on uses a board with several omron relays similar to the type I've seen used in attenuators. This board is used for sampling and monitoring, the relays click several times per second 24 hrs a day 7 days. They have been in service 15 years now and we are just beginning to see some failures. A quality relay would be hard to beat IMHO.
Member
Joined 2002
I had about 200 Mercury wetted relays at one point but the x-gf didn't pay the storage fee for my stuff in another city and they auctioned it all off 🙁 my dad works for telus and he scrounges for all the old stuff. The relays were about 25$ each quiet could hardly hear them clicking but were really really clean.. I miss them. wish i had them would work perfect for this project.
Member
Joined 2002
Question.
Do you have to short the input Neg to GND when running a single ended input and xlr out-put ? I wonder if this is what is making the hushing sound...
Do you have to short the input Neg to GND when running a single ended input and xlr out-put ? I wonder if this is what is making the hushing sound...
Re: Question.
Hushing sound. . . ?
Do you mean that something hides sonic information?
If you make the amp unbalanced input, the gain of the amp is reduced by 6dB.
If the gain of the amp is 12dB with balanced input, it is reduced down to 6dB.
Probably for this reason. . . ?
jleaman said:
Hushing sound. . . ?
Do you mean that something hides sonic information?
If you make the amp unbalanced input, the gain of the amp is reduced by 6dB.
If the gain of the amp is 12dB with balanced input, it is reduced down to 6dB.
Probably for this reason. . . ?
Re: Question.
I have thought through the night. 🙄
This X-BOSOZ has feedback lines from the output to the input.
If the -input is shorted to the ground, the feedback fraction of the
output voltage to the -input will be always fixed. In this case,
the volume control is to be on the output side. Otherwise, the
input volume control on the +input side will cause unbalanced
feedback fractions to +/- input sides.
or 
?
jleaman said:
I have thought through the night. 🙄
This X-BOSOZ has feedback lines from the output to the input.
If the -input is shorted to the ground, the feedback fraction of the
output voltage to the -input will be always fixed. In this case,
the volume control is to be on the output side. Otherwise, the
input volume control on the +input side will cause unbalanced
feedback fractions to +/- input sides.
or ?Member
Joined 2002
I just wish i had a balanced pot to i can try this i don't want to spend 150$ on a pot and this not be the solution.
Jase,
If you want to try it on the cheap, use one el-cheapo stereo pot for each channel of the pre.
i.e. +out of pre to the one channel of a SE pot, and -out to the other channel of the SE pot. Repeat same for the other pre channel using a second stereo SE pot. Adjust the pots to achieve correct volume balance.
Another possible solution for experimentation is to use to create a single position balanced output attenuator using 4 resistors --> a simple voltage divider network.
I agree that you want to try a cheaper test before investing in a higher cost attenuator.
Cheers, Terry
If you want to try it on the cheap, use one el-cheapo stereo pot for each channel of the pre.
i.e. +out of pre to the one channel of a SE pot, and -out to the other channel of the SE pot. Repeat same for the other pre channel using a second stereo SE pot. Adjust the pots to achieve correct volume balance.
Another possible solution for experimentation is to use to create a single position balanced output attenuator using 4 resistors --> a simple voltage divider network.
I agree that you want to try a cheaper test before investing in a higher cost attenuator.
Cheers, Terry
Jason .... For a cheap $45 balanced pot, check this out .... http://www.diyaudio.com/forums/showthread.php?s=&threadid=83158&perpage=10&pagenumber=1
Member
Joined 2002
I have a Solution on the way. Ill be posting idea's and thoughts soon. I hope to get balanced working and also have my ATI chassis on the way. Hope it all fit's and works in this chassis. Metal Man Do you think i should put the PSU in a external Chassis with a well shielded power-cord. ?
jleaman said:
If I simply want to check out the effect of the balanced output pot,
I could make the test output pot with four resistors. 🙂
Hi All,
Can someone tell me what the value of D1 is in the current version of the schematic on this thread. I already know the value from Terrys original. Thank you.
Graeme
Can someone tell me what the value of D1 is in the current version of the schematic on this thread. I already know the value from Terrys original. Thank you.
Graeme
Hello Everyone
Well I am in now my Twisted BOSOZ arrived in the mail today. So I just wanted to thank Russ and Brian for putting toghter such a nice kit. I have built several different kit over the years this one is real nice so well packed the parts are very well marked and all top quality right down to PCB's. This will be my first Pass project and I am very excited about this one. So I will keep every one posted about my progress and I am sure I will have some questions along the way.
Cheers
Dave
Well I am in now my Twisted BOSOZ arrived in the mail today. So I just wanted to thank Russ and Brian for putting toghter such a nice kit. I have built several different kit over the years this one is real nice so well packed the parts are very well marked and all top quality right down to PCB's. This will be my first Pass project and I am very excited about this one. So I will keep every one posted about my progress and I am sure I will have some questions along the way.
Cheers
Dave
D1 on the Preamp is a 6.8 V zener. You can check the BOM at the Twisted Pear Web Site
http://www.twistedpearaudio.com/
Under the listing for the Twisted BOSOZ.
http://www.twistedpearaudio.com/
Under the listing for the Twisted BOSOZ.
Where do you put the power switch?
After blowing out several FETs on my pream boards I realized that one of the power switches may cause the problems. Since I put the power supply into a separate chassis I installed two power switches: One for the PS between the line in and the transformers and one between the preamp boards and the power supply out.When I first turned the power supply on and then the preamp boards the FETs went bad a couple of times. Now I use only the power switch before the power supply and everything behaves well. Any idea what the problem could be, could a high turn on current have killed the FETs or was my switch just defective?
Thanks for any help.
After blowing out several FETs on my pream boards I realized that one of the power switches may cause the problems. Since I put the power supply into a separate chassis I installed two power switches: One for the PS between the line in and the transformers and one between the preamp boards and the power supply out.When I first turned the power supply on and then the preamp boards the FETs went bad a couple of times. Now I use only the power switch before the power supply and everything behaves well. Any idea what the problem could be, could a high turn on current have killed the FETs or was my switch just defective?
Thanks for any help.
Both PS now working
Thanks Brian,
Back on page 116 I requested help with one ps giving erroneous voltage out. Brian and others correctly identified the problem as bat FETS. Brian sent me two new ones and the second ps is now giving the correct output voltages. Now to proceed to completion.
Thanks Brian,
Back on page 116 I requested help with one ps giving erroneous voltage out. Brian and others correctly identified the problem as bat FETS. Brian sent me two new ones and the second ps is now giving the correct output voltages. Now to proceed to completion.
The darn thing works!
My Bosoz nears completion.
First thanks to all...Russ, Brian, Terry, and especially Nelson.😎
Before I get too far I have a question. I'm looking for a linear motoriz(s)ed pot with a good, long, solid full round 1/4" shaft. Any ideas? I know I'm not alone here. Maybe If we find a nice one some of us could get together.
This is the first pre I've built. It's by far the most difficult and complicated piece of DIY audio gear I've built. I usually build my chassis', but I couldn't resist this one that was being tossed at work.
The thing got pretty complicated. It's the usual dual mono Twisted configuration. Add to that the cool Joshua tree that works great! I created a relay based input selector seen rear center. I built the VSPS phono stage seen rear right. The VSPS actually sounds real good. The input selector and phono board are mounted directly in front of thier respective input jacks. A remote volume board will find its way in there too.
No smoke this time and so far it sounds great!
My Bosoz nears completion.
First thanks to all...Russ, Brian, Terry, and especially Nelson.😎
Before I get too far I have a question. I'm looking for a linear motoriz(s)ed pot with a good, long, solid full round 1/4" shaft. Any ideas? I know I'm not alone here. Maybe If we find a nice one some of us could get together.
This is the first pre I've built. It's by far the most difficult and complicated piece of DIY audio gear I've built. I usually build my chassis', but I couldn't resist this one that was being tossed at work.
The thing got pretty complicated. It's the usual dual mono Twisted configuration. Add to that the cool Joshua tree that works great! I created a relay based input selector seen rear center. I built the VSPS phono stage seen rear right. The VSPS actually sounds real good. The input selector and phono board are mounted directly in front of thier respective input jacks. A remote volume board will find its way in there too.
No smoke this time and so far it sounds great!
