[Stefan_DR3]

Does anyone else have a TF2-30?  What are the specs on your cart and is it happy with the impedance?
I read that input impedence is fixed on all TF2 at a very high 47k!

The user manual is misleading so I'm editing my post for the record, based on some info from Bryston and the datasheet for the Jensen transformer inside the TF-2.

The TF2 is like most any other transformer and has a "natural impedance" which is a factor of the turns ratio.  The 47k ohms comes from the MM stage it is most likely connected to.  The formula to calculate the input impedance that a cartridge would "see" is:

Zin = 47,000 ohms * (Turns_Ratio) ^ 2

where the TF2-20 Turns_Ratio is 1:10.

Therefore:

Zin = 47,000  * (0.1) ^ 2 = 47,000 / 100 = 470 ohms 


The TF2-30 turns ratio is much higher (probably 1:35) so its Zin will be lower (< 40 ohms) as expected.  This is probably more important for cartridge matching than the actual voltage gain in dB.


Here's more info on the theory and a table of data on step-up devices:
http://www.mh-audio.nl/StepUp%20Transformer.asp

[95Dyna]

Hi James,

Just received my new BP2 today. I disconnected my existing stage which was working fine and connected the BP2.  When I turned up the volume without a signal I immediately heard a significant hum.  All the IC's and ground cables are connected correctly.  I tried a different jack on the MPS2 as well as a different line level input on the BP26 to no avail. The BP2 is not located anywhere near the Torus, MPS2 or 7Bs. I played one side of a very familiar album and I must say this is a terrific phono stage.  Major improvement across the frequency range especially in bass presence and quality. The hum is very noticeable during quiet passages and during fade outs at the end of tracks.

Any thoughts on what the cause may be? The manual does not have troubleshooting page. Anyone else out there who has a BP2 using the MPS2 please chime in as well.

Thanks,

Bill

[James Tanner]

Hi James,

Just received my new BP2 today. I disconnected my existing stage which was working fine and connected the BP2.  When I turned up the volume without a signal I immediately heard a significant hum.  All the IC's and ground cables are connected correctly.  I tried a different jack on the MPS2 as well as a different line level input on the BP26 to no avail. The BP2 is not located anywhere near the Torus, MPS2 or 7Bs. I played one side of a very familiar album and I must say this is a terrific phono stage.  Major improvement across the frequency range especially in bass presence and quality. The hum is very noticeable during quiet passages and during fade outs at the end of tracks.

Any thoughts on what the cause may be? The manual does not have troubleshooting page. Anyone else out there who has a BP2 using the MPS2 please chime in as well.

Thanks,

Bill

Hi Bill,

Check with Mike - mine at home is dead quiet.

james

[95Dyna]

Thanks James, will do. BTW, are you using PS3 or MPS2 at home with your BP2?

[James Tanner]

Thanks James, will do. BTW, are you using PS3 or MPS2 at home with your BP2?

PS3

[95Dyna]

PS3

Thanks.  I contacted Mike via the contact form on the website. Is that the best way to get ahold of him?  I don't have his direct email address.

[Johnny2Bad]

Thanks.  I contacted Mike via the contact form on the website. Is that the best way to get ahold of him?  I don't have his direct email address.

See post #33 in this thread.

[James Tanner]

Thanks.  I contacted Mike via the contact form on the website. Is that the best way to get ahold of him?  I don't have his direct email address.

mpickett@bryston.com

james

[95Dyna]

mpickett@bryston.com

james

James,

I spoke with Mike today who tells me the BP2 cannot be plugged into a spare outlet on the MPS2. This is why I asked which PS you were using at home.  After all my  troubleshooting my suspicion turned toward something in the MPS2 not being right for the BP2.  "Quiet operation" requires a splitter so the BP2 can be connected to the  same outlet as the BP26.  The required splitter was not included in my shipment.  Mike is sending it to me.

I'm hoping that the sound quality is not compromised over using the PS3.  The word splitter is anathema to many audiophiles.  Hopefully that applies more to signal flow than it does to power distribution especially in this scenario as neither the BP2 nor the BP26 consumes mass quantities of power.

Bill

[Stefan_DR3]

I spoke with Mike today who tells me the BP2 cannot be plugged into a spare outlet on the MPS2. ...  "Quiet operation" requires a splitter so the BP2 can be connected to the  same outlet as the BP26.  The required splitter was not included in my shipment.  Mike is sending it to me.

I'm hoping that the sound quality is not compromised over using the PS3.  The word splitter is anathema to many audiophiles.  Hopefully that applies more to signal flow than it does to power distribution especially in this scenario as neither the BP2 nor the BP26 consumes mass quantities of power.

Bill, did the splitter solve your problem?  If so, I wouldn't sweat it.  These are DC power supplies. 

I found this statement in http://bryston.com/PDF/brochures/PHONO_BROCHURE.pdf:

Your Bryston MPS-2 can power
multiple Bryston electronics
such as the BP-2, BP-26 and
more. Contact Bryston for a
custom DC power cable. An
additional PS-3 is not required.

I am surprised to hear Mike's answer though.  The fact that you can't use another outlet on the MPS2 implies that there is some amount of DC offset between the outputs causing a ground loop.  I wonder if the MPS2 can be re-calibrated.

[Stefan_DR3]

I disconnected my existing stage which was working fine and connected the BP2.  When I turned up the volume without a signal I immediately heard a significant hum.  All the IC's and ground cables are connected correctly. 

Any thoughts on what the cause may be? The manual does not have troubleshooting page. Anyone else out there who has a BP2 using the MPS2 please chime in as well.

I have a brand new BP-17 Cubed with built-in phono stage (same circuit as BP-2 MM) and experiencing a similar problem.  I have been in contact with Bryston tech support who are trying to reproduce my setup.  I also added a TF-2 step-up transformer which seems to exacerbate the hum/buzz.  The TF-2 seems to be working fine in another system so I think something is wrong with the phono board or the way it is wired into the preamp.

[95Dyna]

I have a brand new BP-17 Cubed with built-in phono stage (same circuit as BP-2 MM) and experiencing a similar problem.  I have been in contact with Bryston tech support who are trying to reproduce my setup.  I also added a TF-2 step-up transformer which seems to exacerbate the hum/buzz.  The TF-2 seems to be working fine in another system so I think something is wrong with the phono board or the way it is wired into the preamp.

Hi Stefan,

I sent you a PM.  Thanks for responding

[Stefan_DR3]

I have a brand new BP-17 Cubed with built-in phono stage (same circuit as BP-2 MM) and experiencing a similar problem.  I have been in contact with Bryston tech support who are trying to reproduce my setup.  I also added a TF-2 step-up transformer which seems to exacerbate the hum/buzz.  The TF-2 seems to be working fine in another system so I think something is wrong with the phono board or the way it is wired into the preamp.

It's been a month so time for an update. 

• The TF-2 has only a chassis ground (it is a passive component) which goes nowhere unless "daisy chained" to the preamp's ground terminal.  But when I connect the ground terminals with a spare wire the noise gets much louder.
• Mike @ Bryston is looking for a grounding fix within the TF-2.
• The TF-2 on its own works fine with same turntable connected to my old Yamaha receiver.
• My Sonic Frontiers Phono stage works fine with the Bryston preamp (line input) and same turntable.

At this point I am ready to send them the MM phono board and/or the TF-2 because no matter how I connect the ground the phono is unusable.  Just waiting for Bryston to provide RMA ... 

[James Tanner]

It's been a month so time for an update. 

• The TF-2 has only a chassis ground (it is a passive component) which goes nowhere unless "daisy chained" to the preamp's ground terminal.  But when I connect the ground terminals with a spare wire the noise gets much louder.
• Mike @ Bryston is looking for a grounding fix within the TF-2.
• The TF-2 on its own works fine with same turntable connected to my old Yamaha receiver.
• My Sonic Frontiers Phono stage works fine with the Bryston preamp (line input) and same turntable.

At this point I am ready to send them the MM phono board and/or the TF-2 because no matter how I connect the ground the phono is unusable.  Just waiting for Bryston to provide RMA ... 

\\

Hi

The current TF2 seems to work fine with our own Bryston turntable as is but  i am playing around at home with the TF2 and a modification we have tried on other tables and will let you know.

james

[95Dyna]

It's been a month so time for an update. 

• The TF-2 has only a chassis ground (it is a passive component) which goes nowhere unless "daisy chained" to the preamp's ground terminal.  But when I connect the ground terminals with a spare wire the noise gets much louder.
• Mike @ Bryston is looking for a grounding fix within the TF-2.
• The TF-2 on its own works fine with same turntable connected to my old Yamaha receiver.
• My Sonic Frontiers Phono stage works fine with the Bryston preamp (line input) and same turntable.

At this point I am ready to send them the MM phono board and/or the TF-2 because no matter how I connect the ground the phono is unusable.  Just waiting for Bryston to provide RMA ... 

It's been 2.5 months since I received my BP2  unusable out of the box due to excessive hum. After extensive troubleshooting of my own and multiple trial and error at  Mike's direction and several weeks of engineering investigation Mike instructed me to send it back to be serviced as they think there is an improperly wired internal ground in the MM section.  He said he thinks the problem is in my particular unit and not a BP2 problem at  large.  Based on your experience I'm not  so sure.  I don't expect a resolution to this before the new year the way things  are going.

[95Dyna]

Hi Bill,

Check with Mike - mine at home is dead quiet.

james

Hi James,

Can you please check on the status of my BP2.  It was DOA when I bought it back in October (see above post for details). I emailed Mike for an update but he is off until 1/3. I copied you with the message trail if that helps.

Thanks,

Bill

[James Tanner]

Hi James,

Can you please check on the status of my BP2.  It was DOA when I bought it back in October (see above post for details). I emailed Mike for an update but he is off until 1/3. I copied you with the message trail if that helps.

Thanks,

Bill

Hi Bill

Ok I will look into it.

James

[James Tanner]

Hi Bill

I tried to find out what was happening but Mike is the one doing the mode so I am sorry but will not be able to get back to you till Tuesday.

James

[95Dyna]

Hi Bill

I tried to find out what was happening but Mike is the one doing the mode so I am sorry but will not be able to get back to you till Tuesday.

James

OK, thanks James.  While I have your attention what is Bryston's official policy when a customer is shipped a new piece of equipment that is DOA or unusable?  It doesn't seem consistent with what I know Bryston to be to have the customer go through a lengthy trial and error process (in this case it will be three months) with long intervals between responses/updates.  At this point I still don't know what's wrong or if there is a fix.  No hard feelings intended as I know nothing runs perfectly all the time and you guys do an excellent job otherwise.

Regards,

Bill

[James Tanner]

OK, thanks James.  While I have your attention what is Bryston's official policy when a customer is shipped a new piece of equipment that is DOA or unusable?  It doesn't seem consistent with what I know Bryston to be to have the customer go through a lengthy trial and error process (in this case it will be three months) with long intervals between responses/updates.  At this point I still don't know what's wrong or if there is a fix.  No hard feelings intended as I know nothing runs perfectly all the time and you guys do an excellent job otherwise.

Regards,

Bill

Hi Bill

Yes it is frustrating I know - I think the issue is we have lots of phono stages out there with no issues and this one seems really weird.  According to Mike I believe he can not seem to duplicate the problem and did not want to return it or another unit and have the same issue.

james