Does anyone have the schematics of the Rotel RQ-970BX phono preamp.
I'm using one, but the problem is that the output is quite low compared with my CD player. My linestage does not have enough gain so normal listening levels are now with the potmeter almost full open. That's why I want to try to get some more gain out of the Rotel.
Anyone ?
I'm using one, but the problem is that the output is quite low compared with my CD player. My linestage does not have enough gain so normal listening levels are now with the potmeter almost full open. That's why I want to try to get some more gain out of the Rotel.
Anyone ?
Sjef
I am reading and seeing the schematic . I find it in an Italian review.
This phono stage has a differential pair at the input , and a part of the eq (hi freq) is in this stage .
Every feedback loop in the op amps is also a eq stage.
So I think the only way for increasing the gain without affecting the RIAA curve is R123 , between IC101 (AD744JN) and ICI103 (NE5534AN) . R123 is now 75K and connects the output of IC101 and the input of IC103 . Try decreasing value of this resistor.
I am reading and seeing the schematic . I find it in an Italian review.
This phono stage has a differential pair at the input , and a part of the eq (hi freq) is in this stage .
Every feedback loop in the op amps is also a eq stage.
So I think the only way for increasing the gain without affecting the RIAA curve is R123 , between IC101 (AD744JN) and ICI103 (NE5534AN) . R123 is now 75K and connects the output of IC101 and the input of IC103 . Try decreasing value of this resistor.
Decreasing this resistor would not help much in winning gain because it sees a very high impednace at the input of the second opamp.
I was afraid that the riaa correction was done in the feedback lines of both the opamps. I was hoping that the second opamp was only a linear amplifying stage, so then it would not be a problem to set it's gain for another extra 10dB or so.
Still want the schematic. Maybe I can recalculate the riaa eq and set it for higer gain.
I was afraid that the riaa correction was done in the feedback lines of both the opamps. I was hoping that the second opamp was only a linear amplifying stage, so then it would not be a problem to set it's gain for another extra 10dB or so.
Still want the schematic. Maybe I can recalculate the riaa eq and set it for higer gain.
Here is a partial schematic. Never mind the input transistor types, they are just placeholders.
I'd suggest to modify the two gain setting resistors by soldering additional values on top of them.
R117=560 and sets MM gain. Another 560 on top gives you an extra 6dB without much pain.
R119=47 sets MC gain. Same story, put a 47 on top.
Same for the other channel.
You could tweak R125=4k7 too, but eventually this will lead to aberrations in the RIAA response.
I'd suggest to modify the two gain setting resistors by soldering additional values on top of them.
R117=560 and sets MM gain. Another 560 on top gives you an extra 6dB without much pain.
R119=47 sets MC gain. Same story, put a 47 on top.
Same for the other channel.
You could tweak R125=4k7 too, but eventually this will lead to aberrations in the RIAA response.
Attachments
Photo 1 of 17, Rotel RQ970BX HFW -Andy Grove upgrade
and the Rotel RHQ-10 (RHQ10) phono preamp tech manual is on the same page. Older Rotel schematics can be obtained via direct contact with Rotel, via email, or even calling them first.
Many times the email with the tech schematic will be sent to you in the same day as first contact. Cudos to Rotel for being a great company.
and the Rotel RHQ-10 (RHQ10) phono preamp tech manual is on the same page. Older Rotel schematics can be obtained via direct contact with Rotel, via email, or even calling them first.
Many times the email with the tech schematic will be sent to you in the same day as first contact. Cudos to Rotel for being a great company.
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All rotel (and B&W and Classe) service manuals can be found at:
B&W Group North America Service & Support Homepage
You have to click on the Service Manuals link and then click on a button to agree to some terms and conditions before they let you view the service manuals...
B&W Group North America Service & Support Homepage
You have to click on the Service Manuals link and then click on a button to agree to some terms and conditions before they let you view the service manuals...
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