Bv8 vs. Bv11

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Bv8 vs. Bv11

Postby boltor64 » Fri May 16, 2014 4:31 am

Hi all,

I'm currently modding a Nady 1050 and Apex 460. I have followed Dave's instructions and have completed everything except the transformer replacement. It seems like the Bv8 is the replacement for the Nady 1050 and the Bv11 is for the Apex 460. Can someone explain the differences in these two transformers? Would it matter if I used the Bv8 on both mics? It appears that the Bv8 is smaller than the Bv11 so it would be an easier replacement as it would fit into the existing bell housing. Would the Bv11 fit as well? FWIW, I have used an RK 47 capsule in the Nady and a RK12 in the Apex.

Mark
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Re: Bv8 vs. Bv11

Postby boltor64 » Mon May 19, 2014 10:23 am

Just an update:

I went ahead and ordered the Bv11 and Bv8 a couple of days ago. I'm not sure if there is a wiring diagram included with the transformers...If not, could someone please tell me how to wire the new transformer to the existing wires (in terms of color, as the colors are different in the AA transformers compared to the stock).

Much appreciated.

Mark
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Re: Bv8 vs. Bv11

Postby Dave Thomas » Wed May 28, 2014 10:45 am

Hi Mark, sorry for the delay in answering. We updated the IMAC software and now it consistently kicks me off the Internet and I have to re-boot to get access to the server again.

There is no wiring diagram with the transformers. They have the exact same wiring color and configuration as the transformer in the stock APEX 460 or Nady TCM 1050.

The Red is the (hot) primary going to the output of the tube via C8 in an APEX 460. The White wire is GND/common and can be wired directly to pins 4&7 on the 7 pin connector.

Ther is around 1K ohm dc on the primary side and about 90 ohms dc across the secondary side. The Green wire is (hot) and goes to pin 6 of the 7 pin and the Green wire is (cold) and goes to pin 5 of the 7 pin connector.

The BV8 has a turns ratio of 6.5:1 exactly the same turns ratio as the original U47 transformer and is has a dual bobbin configuration with iron laminations.
The BV8 sounds slightly more "vintage" than the BV11.

The BV11 has a ratio of 5:1 and has a dual bobbin configuration but with bi-metal laminations and sounds like the T14 used in the original C12 which has a 14:1 ratio.

The 14:1 ratio is required when driving a transformer directly from the plate of a 6072a like the original C12 circuit.

However, if you take a page from the Bill Putnam LA2a compressor and drive the transformer from the cathode of the 2nd half of the 6072a then you can drive the 5:1 transformer with impunity and achieve 9db less loss with the 5:1 transformer.

Cheers, Dave



boltor64 wrote:Just an update:

I went ahead and ordered the Bv11 and Bv8 a couple of days ago. I'm not sure if there is a wiring diagram included with the transformers...If not, could someone please tell me how to wire the new transformer to the existing wires (in terms of color, as the colors are different in the AA transformers compared to the stock).

Much appreciated.

Mark
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Re: Bv8 vs. Bv11

Postby Dave Thomas » Wed May 28, 2014 10:47 am

Dave Thomas wrote:Hi Mark, sorry for the delay in answering. We updated the IMAC software and now it consistently kicks me off the Internet and I have to re-boot to get access to the server again.

There is no wiring diagram with the transformers. They have the exact same wiring color and configuration as the transformer in the stock APEX 460 or Nady TCM 1050.

The Red is the (hot) primary going to the output of the tube via C8 in an APEX 460. The White wire is GND/common and can be wired directly to pins 4&7 on the 7 pin connector.

There is around 1K ohm dc on the primary side and about 90 ohms dc across the secondary side. The Green wire is (hot) and goes to pin 6 of the 7 pin and the Green wire is (cold) and goes to pin 5 of the 7 pin connector.

The BV8 has a turns ratio of 6.5:1 exactly the same turns ratio as the original U47 transformer and it has a dual bobbin configuration with iron laminations.
The BV8 sounds slightly more "vintage" than the BV11.

The BV11 has a ratio of 5:1 and has a dual bobbin configuration but with bi-metal laminations and sounds like the T14 used in the original C12 which has a 14:1 ratio.

The 14:1 ratio is required when driving a transformer directly from the plate of a 6072a like the original C12 circuit.

However, if you take a page from the Bill Putnam LA2a compressor and drive the transformer from the cathode of the 2nd half of the 6072a then you can drive the 5:1 transformer with impunity and achieve 9db less loss with the 5:1 transformer.

Cheers, Dave



boltor64 wrote:Just an update:

I went ahead and ordered the Bv11 and Bv8 a couple of days ago. I'm not sure if there is a wiring diagram included with the transformers...If not, could someone please tell me how to wire the new transformer to the existing wires (in terms of color, as the colors are different in the AA transformers compared to the stock).

Much appreciated.

Mark
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Posts: 167
Joined: Mon Dec 30, 2013 2:46 pm

Re: Bv8 vs. Bv11

Postby justinheronmusic » Mon Aug 10, 2015 5:30 pm

What pins to the green, yellow, black, and white wires from the PCB go to? Do they get soldered together with the white, black, and green leads of the transformer?

Dave Thomas wrote:Hi Mark, sorry for the delay in answering. We updated the IMAC software and now it consistently kicks me off the Internet and I have to re-boot to get access to the server again.

There is no wiring diagram with the transformers. They have the exact same wiring color and configuration as the transformer in the stock APEX 460 or Nady TCM 1050.

The Red is the (hot) primary going to the output of the tube via C8 in an APEX 460. The White wire is GND/common and can be wired directly to pins 4&7 on the 7 pin connector.

Ther is around 1K ohm dc on the primary side and about 90 ohms dc across the secondary side. The Green wire is (hot) and goes to pin 6 of the 7 pin and the Green wire is (cold) and goes to pin 5 of the 7 pin connector.

The BV8 has a turns ratio of 6.5:1 exactly the same turns ratio as the original U47 transformer and is has a dual bobbin configuration with iron laminations.
The BV8 sounds slightly more "vintage" than the BV11.

The BV11 has a ratio of 5:1 and has a dual bobbin configuration but with bi-metal laminations and sounds like the T14 used in the original C12 which has a 14:1 ratio.

The 14:1 ratio is required when driving a transformer directly from the plate of a 6072a like the original C12 circuit.

However, if you take a page from the Bill Putnam LA2a compressor and drive the transformer from the cathode of the 2nd half of the 6072a then you can drive the 5:1 transformer with impunity and achieve 9db less loss with the 5:1 transformer.

Cheers, Dave



boltor64 wrote:Just an update:

I went ahead and ordered the Bv11 and Bv8 a couple of days ago. I'm not sure if there is a wiring diagram included with the transformers...If not, could someone please tell me how to wire the new transformer to the existing wires (in terms of color, as the colors are different in the AA transformers compared to the stock).

Much appreciated.

Mark
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Re: Bv8 vs. Bv11

Postby mhelin » Sun Sep 30, 2018 1:21 pm

Hi, how is the new larger core BV8 coming, when can we expect it to be available (also from your EU shop)? Also it it like the original, wound on 4-slot bobbins and using a high Ni-% core laminations?

Btw, Is it the "BV08" labelled one on right in this picture:
Image
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