Suggestion: Output tube in SET amp for midbass frequency

HP8903B · 28th January 2013, 03:16 AM

I want to build a SET amp for midbass frequency.

The frequency is 100Hz - 250Hz
The driver is 105dB compression bass driver.

I would like some suggestions on a good output tube.

enzoastro · 28th January 2013, 04:52 PM

How about a 6c33 in cathode follower thru a transformer, should get good damping that way?

enzo

palmas · 28th January 2013, 04:55 PM

GM70

HP8903B · 28th January 2013, 04:56 PM

I don't need that kind of power.
I plan to use a GM-70 for the 16" woofer for below 100Hz

HP8903B · 28th January 2013, 04:57 PM

I think 6C33 and GM-70 are too much for this application.

My compression driver is very efficient. It has 125mm diaphragm.

palmas · 28th January 2013, 05:00 PM

Quote:

Originally Posted by manp111

I think 6C33 and GM-70 are too much for this application.

My compression driver is very efficient. It has 125mm diaphragm.

Then go for a 300B

HP8903B · 28th January 2013, 05:01 PM

I plan to use 45 tubes for the top 3 drivers.

HP8903B · 28th January 2013, 05:03 PM

Quote:

Then go for a 300B

Someone also made the same suggestion.
He used 300B to drive his midbass compression driver as well.

My concern with 300B is that it is too expensive.

cotdt · 05:32 PM

I like the sound quality of 45, 2A3, and 300B, basically any low-mu DHT with parallel plate construction.

You can never have too much power! You don't have to use it.

I would go with 300B or 2A3 for all sections. The important thing for the midbass is the damping factor, and 300B is best at it, with 2A3 very close. In fact, modern 2A3 and 300B is the same, just different voltage filaments.

If you need a lot of tubes, it is best to go for tubes that are still in production. Some NOS tubes are cheap today, but won't be in 10 years as inventory runs dry. You'll have to rebuild your amp for new tubes, with new and expensive output transformers. In 100 years, they will still be making 300B tubes.

palmas · 28th January 2013, 05:32 PM

Quote:

Originally Posted by manp111

Someone also made the same suggestion.
He used 300B to drive his midbass compression driver as well.

My concern with 300B is that it is too expensive.

You're using 45 and complaining about the price of a 300B?

Use 300B for all, or if you need much more power, use the GM70

28th January 2013, 03:16 AM	#1
HP8903B diyAudio Member Join Date: Jun 2010 Location: Texas	Suggestion: Output tube in SET amp for midbass frequency I want to build a SET amp for midbass frequency. The frequency is 100Hz - 250Hz The driver is 105dB compression bass driver. I would like some suggestions on a good output tube.

28th January 2013, 05:29 PM	#9
cotdt diyAudio Member Join Date: Oct 2005	I like the sound quality of 45, 2A3, and 300B, basically any low-mu DHT with parallel plate construction. You can never have too much power! You don't have to use it. I would go with 300B or 2A3 for all sections. The important thing for the midbass is the damping factor, and 300B is best at it, with 2A3 very close. In fact, modern 2A3 and 300B is the same, just different voltage filaments. If you need a lot of tubes, it is best to go for tubes that are still in production. Some NOS tubes are cheap today, but won't be in 10 years as inventory runs dry. You'll have to rebuild your amp for new tubes, with new and expensive output transformers. In 100 years, they will still be making 300B tubes. Last edited by cotdt; 28th January 2013 at 05:32 PM.

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28th January 2013, 04:52 PM	#2
enzoastro diyAudio Member Join Date: Oct 2010 Location: se england	How about a 6c33 in cathode follower thru a transformer, should get good damping that way? enzo

28th January 2013, 04:55 PM	#3
palmas diyAudio Member Join Date: Jun 2007	GM70

28th January 2013, 04:56 PM	#4
HP8903B diyAudio Member Join Date: Jun 2010 Location: Texas	I don't need that kind of power. I plan to use a GM-70 for the 16" woofer for below 100Hz

28th January 2013, 04:57 PM	#5
HP8903B diyAudio Member Join Date: Jun 2010 Location: Texas	I think 6C33 and GM-70 are too much for this application. My compression driver is very efficient. It has 125mm diaphragm.

28th January 2013, 05:01 PM	#7
HP8903B diyAudio Member Join Date: Jun 2010 Location: Texas	I plan to use 45 tubes for the top 3 drivers.