Stereomour vs. Tucker 45...?
- Thread starter faithintruth
- Start date
Paul Joppa
Moderator
I'm getting 10CF tuned 36Hz; with a sand amp it would be more like 5CF - looks like the box is already well tuned for SETs.
The box is tuned to about 42 Hz. I will experiment with restricting the air flow through the port (2.5"x11"x0.75" slot) with foam or some fibrous material to lower the tuning a bit.
Could you describe how you calculated the box size and tuning for the high(er) impedance amp?
Jim
Could you describe how you calculated the box size and tuning for the high(er) impedance amp?
Jim
Paul Joppa
Moderator
I increased the speaker's QE in proportion to the effective source resistance.
Roughly, the tube plate resistance is about 700 ohms; add in the transformer primary resistance plus the secondary DC resistance times the turns ratio squared to get about 900 ohms. The nominal reflected load resistance is the primary impedance rating, 3000 ohms. Multiply QE by 3900/3000 = 1.3 times, and run some software (I'm lazy!)
You can lower the tuning by making the opening smaller. Most speaker design free software will have a calculator. Measurements are better, but it's easiest to measure if you have a 2-channel oscilloscope.
Roughly, the tube plate resistance is about 700 ohms; add in the transformer primary resistance plus the secondary DC resistance times the turns ratio squared to get about 900 ohms. The nominal reflected load resistance is the primary impedance rating, 3000 ohms. Multiply QE by 3900/3000 = 1.3 times, and run some software (I'm lazy!)
You can lower the tuning by making the opening smaller. Most speaker design free software will have a calculator. Measurements are better, but it's easiest to measure if you have a 2-channel oscilloscope.
Paul Joppa
Moderator
Exactly.
faithintruth
New member
By the way Paul, is the iron used in the Stereomour supplied by Magnequest? Any brand name parts?
Paul Joppa
Moderator
No boutique parts - we choose the parts carefully, including listening comparisons, but also try to keep the cost down. The transformers are my own designs.
In another thread the question of a suitable Magnequest output transformer and plate choke came up. The question is at present still unanswered.
In another thread the question of a suitable Magnequest output transformer and plate choke came up. The question is at present still unanswered.
Natural Sound
New member
Like galyons I have Paramour II's set to run 45's. In addition I have the SEX/Stereomour iron installed. I ran the system for a couple of years with 2A3's. Then a friend gave a pair of 45's and I decided to try them. Lets just say that the 45's never came out. There are arguments for both tubes. But for me, my listening room, speakers (Orcas/Subs) and music taste, the 45 was preferred. As they say YMMV.
As mentioned here previously the 2A3 tube can safely operate in the 45 configuration but NOT the other way around. So if you wire it for a 45 you can tube roll 2A3 and 45's for comparison. Just make sure that the amp and tubes have been given ample time to burn in before doing any critical listening.
As mentioned here previously the 2A3 tube can safely operate in the 45 configuration but NOT the other way around. So if you wire it for a 45 you can tube roll 2A3 and 45's for comparison. Just make sure that the amp and tubes have been given ample time to burn in before doing any critical listening.
You will find the same level of parts quality in our products that you would find in many Stereophile class A rated components. This includes the coupling capacitors, resistors, diodes, sockets, and switches, etc.faithintruth said:
We select our parts for reliability, good in-circuit performance, and ease of acquisition. Our high end Tube Repro uses a lot of botique parts, and it can take me days chasing down multiple vendors to find what I need to complete the build.
-PB
Paul Joppa
Moderator
Now it's answered, Mike is not going to do a suitable transformer.Paul Joppa said:
faithintruth
New member
That the Stereomour is configurable as a 45 amp but 2A3's can also be rolled in is a huge option for me. Thanks to everyone for sharing.
faithintruth
New member
PJ,
Here is a quote from you:
"The design is optimized for the 2A3; to run a 45 the power supply voltage is dropped about 30 volts by increasing a power supply resistance. This resistor gets pretty hot! Significantly increasing the heat under the chassis is not recommended without changing the layout, and perhaps increasing the ventilation area - i.e. to do so reliably is not a minor alteration.
For conservative operation, I recommend running the 2A3 as if it were a 45 - much easier to do."
(The above is exerted from a January 2015 posting)
I think I'll avoid the major alterations and go for the Tucker 45
Here is a quote from you:
"The design is optimized for the 2A3; to run a 45 the power supply voltage is dropped about 30 volts by increasing a power supply resistance. This resistor gets pretty hot! Significantly increasing the heat under the chassis is not recommended without changing the layout, and perhaps increasing the ventilation area - i.e. to do so reliably is not a minor alteration.
For conservative operation, I recommend running the 2A3 as if it were a 45 - much easier to do."
(The above is exerted from a January 2015 posting)
I think I'll avoid the major alterations and go for the Tucker 45
