[HaVoC-28]

  I can't believe a brand new Tobby is going for 500 bucks. That's insane. No wonder Firestone is pissed off.

 
On certain period they do massive rebate , but a DAC dont cost much to assemble so they can afford doing this and keep generous profits

 

 

[labeelen]

@ islandman, anything you can share with us about your findings after the opamp rolling in the Tobby?

I'm planning of trying the lme49990 in both the Tobby and Bobby

 

[labeelen]

Just replaced the 4x default opa604 with 4x lme49990.

First impressions are overwelming: lifts the Bobby performance to new levels. The slight veil I perceived from my balanced HD650 has vanished and every aspect of the sonic picture has improved (space, control, sweeter highs, better definition...)

Feels like arriving in Audio Nirwana

Cheers,

Louis

 

[labeelen]

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[labeelen]

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[tvolpe1600]

Interesting. Can you let us know where you got the lme49990 chips from? And approx price? Also, was it pretty easy to swap the chips?

 

[labeelen]

I had a few available to roll the 4 opa604 in Bobby, not enough (yet) to roll all 7 (dual) opa2604 in Tobby.
In fact I'm interested in hearing your opinions on where (i/v conversion, lpf, rca-out) rolling would make most sence.
To my knowledge prices are low and these parts are generally available, swapping is a piece of cake (I soldered soic tot dip myself btw)

 

[project86]

I had a few available to roll the 4 opa604 in Bobby, not enough (yet) to roll all 7 (dual) opa2604 in Tobby.
In fact I'm interested in hearing your opinions on where (i/v conversion, lpf, rca-out) rolling would make most sence.
To my knowledge prices are low and these parts are generally available, swapping is a piece of cake (I soldered soic tot dip myself btw)

 
You don't need that 7th opamp if you use XLR outputs. I'd start with I/V and then add LPF later. But honestly it's more of a "try it and see" type situation. 

 

[labeelen]

   
You don't need that 7th opamp if you use XLR outputs. I'd start with I/V and then add LPF later. But honestly it's more of a "try it and see" type situation. 

Thanks for the suggestion.
I fully agree with your "try it and see" remark.
 
As follow up to my earlier enthusiasm I have to confess that after additional A/B comparisons I find the 4x LME49990 in the Bobby to 'polite'.
For the time being I've returned to the stock OPA604.
 
As soon as I have finished my 4x LME49710HA I will swap the OPA604's and report back my findings.

 

[project86]

  Thanks for the suggestion.
I fully agree with your "try it and see" remark.
 
As follow up to my earlier enthusiasm I have to confess that after additional A/B comparisons I find the 4x LME49990 in the Bobby to 'polite'.
For the time being I've returned to the stock OPA604.
 
As soon as I have finished my 4x LME49710HA I will swap the OPA604's and report back my findings.

 
Thanks for the update. I have found that using "better" opamps does not always translate to improved sound. It really comes down to the individual implementation - I don't agree with people who say "OPA604 sounds this way, LM4562 is warm, OPA627 is bright"... I just don't think you can classify them independent of the surrounding circuit. The designers often try multiple opamps and settle on the one they like best. Firestone probably did just that. I know Yulong did an exhaustive trial before choosing the OPA2604 in their new Sabre A28 amp. They could have used anything they wanted and OPA2604 is where they ended up. 
 
I'm still glad Firestone chose to socket their opamps. Makes it easy to tune the device for taste. But I wouldn't assume swapping will always be an improvement.

 

[labeelen]

Thanks for the update. I have found that using "better" opamps does not always translate to improved sound. It really comes down to the individual implementation - I don't agree with people who say "OPA604 sounds this way, LM4562 is warm, OPA627 is bright"... I just don't think you can classify them independent of the surrounding circuit. The designers often try multiple opamps and settle on the one they like best. Firestone probably did just that. I know Yulong did an exhaustive trial before choosing the OPA2604 in their new Sabre A28 amp. They could have used anything they wanted and OPA2604 is where they ended up. 

I'm still glad Firestone chose to socket their opamps. Makes it easy to tune the device for taste. But I wouldn't assume swapping will always be an improvement.

I fully agree with the above.
Both LME49990 and LME49710HA are without doubt excellent audio opamps but, to my ears, bring no improvements in the (already excellent) Bobby.
My recent test with OPA602BP however fractionally reduced the bass and warmth of the Bobby and therefore combines very well with my balanced HD650 (which was a little bass-heavy and on the warm side)
(btw I performed my tests with Tobby DAC and van den Hull Integration Hybrid interconnects, both RCA and XLR)

 

[labeelen]

After numerous opamp combinations I finally settled on:

8x opa827 on browndog dual soic to dip8 adapters for I/V section of the Tobby DAC
6x ada4627-1brz on browndog dual soic to dip8 adapters for lpf

Significant improvement over the stock 7x opa2604 in:
- transparency
- musicallity
- subtle sparkling highs
- detail and soundstage

Tested with:
- Tranparrent super ballanced interconnects
- Beyer T90
- Bobby headphone amp with 4x ada4627-1 brz (more detailed and spacious sound)
- 2nd Bobby headphone amp with 4x opa827 (warmer sound)
- squeezebox touch with custom linear PSU

Finnaly arrived in audio Nirwana

 

[brodjagabr1]

   
Thanks for the update. I have found that using "better" opamps does not always translate to improved sound. It really comes down to the individual implementation - I don't agree with people who say "OPA604 sounds this way, LM4562 is warm, OPA627 is bright"... I just don't think you can classify them independent of the surrounding circuit. The designers often try multiple opamps and settle on the one they like best. Firestone probably did just that. I know Yulong did an exhaustive trial before choosing the OPA2604 in their new Sabre A28 amp. They could have used anything they wanted and OPA2604 is where they ended up. 
 
I'm still glad Firestone chose to socket their opamps. Makes it easy to tune the device for taste. But I wouldn't assume swapping will always be an improvement.

The most valuable review i have ever seen. One man made two [$250+$250] opamps moding for Creative Sound Blaster ZxR, and  said it's supercool. So did I too, well - i did not hear a big difference, - $500 for nothing.

 

[scriabinist]

Could anyone please tell me if they can hear a small humming sound when you turn the TOBBY on (blue light on)? It goes away when you turn the unit onto standby.
 
Thanks.

 

[labeelen]

I can confirm this.

Tobbys transformer makes a humming sound that can be heard within 1.5meter from the unit.
Bobby is more silent.

regards,

Louis