A few questions

[ebag4]

What is required to go from AC to DC filaments?  If someone decided to build the amp stock and later change to DC filaments how big a rebuild is involved? 

Assuming noise is not an issue using the original Stereomour with AC filaments, would noise be the same or greater given the additional output power of the 300B?

Given the same source and the fact that the Kaiju and the Stereomour both have a gain of 8dB, can one expect additional output/volume and headroom from a given set of speakers from the Kaiju?  I seem to recall someone feeling the Paramounts did not give them the additional volume they anticipated from doubling the output power.


Thanks,
Ed

 

[ebag4]

OK, I'm in. Ordered without the DC filament upgrade for now.

Another couple of questions:
*What is the input impedance?
*is what is written in the Paramount forum applicable to the Kaiju with regard to capacitance values?

Thanks,
Ed

 

[Paul Birkeland]

What is required to go from AC to DC filaments?  If someone decided to build the amp stock and later change to DC filaments how big a rebuild is involved? 

We would prefer that you do it this way.  The actual process of integrating this into the Kaiju is pretty straightforward.

Assuming noise is not an issue using the original Stereomour with AC filaments, would noise be the same or greater given the additional output power of the 300B?

Noise is a little higher because there's 5V of AC on the filament of the 300B, and the output iron in the Kaiju has a smaller step-down ratio.  We did test the amp on Doc B's 96dB woofer array and the noise floor was not problematic.

Given the same source and the fact that the Kaiju and the Stereomour both have a gain of 8dB, can one expect additional output/volume and headroom from a given set of speakers from the Kaiju?  I seem to recall someone feeling the Paramounts did not give them the additional volume they anticipated from doubling the output power.

Neither the Kaiju or Stereomour have 8dB of gain. They are both in the 15-18dB of gain range.  The Stereomour and Kaiju would play at roughly the same level until the Stereomour started clipping, then you would still be able to crank your preamp up a bit more into the Kaiju.  Do note that gain and power are fairly independent, you could put a 12AX7 in a Stereomour and it would make full power with less rotation of the level control than it did before, but would still make the same power.

 

[ebag4]

Thanks PB, much appreciated.

Best,
Ed

 

[ebag4]

Neither the Kaiju or Stereomour have 8dB of gain. They are both in the 15-18dB of gain range.

From Kaiju page:

Gain: About 8 at the 8 ohm output tap (21.5 dBV)

Confusion sets in....

Best,
Ed

 

[Paul Birkeland]

If you put 1V into the amplifier and get 8V out, you have 8X amplification, which is a gain of 18dB or so. (hence the "about" 8x, since it's listed at 21.5dBV)

 

[ebag4]

Gotcha, thanks again PB.

Do you know the answer to these?...

Another couple of questions:
*What is the input impedance?
*is what is written in the Paramount forum applicable to the Kaiju with regard to capacitance values?

Best,
Ed

 

[Paul Birkeland]

*What is the input impedance?
*is what is written in the Paramount forum applicable to the Kaiju with regard to capacitance values?

The input impedance is 100K.

The coupling caps are 0.1uF/630V and the parallel feed capacitors are 10uF/630V.

-PB

 

[Paul Joppa]

Just to affirm what PB said - the AC-filament hum will be nominally 7dB louder that a Stereomour. That's 6dB for the doubling of filament voltage, and another dB for the transformer ratio. Most people don't need DC filaments, but those with super-sensitive speakers (typically 100dB+) might. It's expensive so we de-coupled it. (Then I ran off with the money saved and spent it on new chokes and output transformers!) The DC supply resides on a board that mounts over the power transformer.

The plate choke is larger; we measured 43.5 henries at 75mADC. Kaiju runs 70mA so about 45 henries - compared to 24 henries for the old Paramount choke. That is the reason the parafeed cap is larger, and the bass is deeper.

The output transformer s also much larger, so you can get full power down to 22Hz - Paramount was 30Hz, and the old original Paramour with the Speco could only manage about 65Hz before max power started to drop. With most speakers you don't hear more bass, but you DO hear cleaner, more relaxed bass. I am quite proud of this transformer design.

 

[ebag4]

Thanks Paul, I appreciate the additional information.  I was back and forth whether to go with the Kaiju or put a Beepree in front of my Stereomour, I feel the Stereomour is so good it is hard to imagine improving on it.  With my 94dB speakers I believe I need a bit more power, likely in conjunction with additional gain (currently running a little iFi iTube pre, 6dB of gain), so I went with the Kaiju. My source has 4v out, so I will try both with and without the pre. 

The Kaiju will be high passed around 3dB down at 70Hz.  I was going to accomplish this by using a .022ufd  cap in series (assuming 100k input impedance) with the input, is there a better way to do this by adjusting the value of the coupling cap perhaps?

Edit: II just read your edit, i am sorry to say that I won't be making good use of the lowest frequencies due to my speaker system.

Thanks,
Ed

 

[ebag4]

The Kaiju will be high passed around 3dB down at 70Hz.  I was going to accomplish this by using a .022ufd  cap in series (assuming 100k input impedance) with the input, is there a better way to do this by adjusting the value of the coupling cap perhaps?

Is off base, should I simply locate an additional cap in line with the low level audio?  My preference would be to avoid adding another cap.

Thanks,
Ed

 

[Paul Birkeland]

You can adjust the coupling cap to limit LF response. 

-PB

 

[Paul Joppa]

You can adjust the coupling cap to limit LF response. 

-PB

To expand a little - that will protect the 300B and the output transformer from deep bass, but will not protect the driver stage. It will probably at 70Hz, since the driver has some headroom, but there is less than 6dB headroom so at higher frequencies oone would miss most of the power advantage of filtering out the bass.

 

[ebag4]

To expand a little - that will protect the 300B and the output transformer from deep bass, but will not protect the driver stage. It will probably at 70Hz, since the driver has some headroom, but there is less than 6dB headroom so at higher frequencies oone would miss most of the power advantage of filtering out the bass.

Thanks PJ/PB, much appreciated.  PJ, the reason I need to hi pass the amp is due to my speaker setup, the mid/tweet section does not have a hi pass section in the crossover.  At 8 watts I could drive the speakers full range without damage, however the design is intended to remove the lowest frequencies for the cleanest output.  What would you do to make this happen at the amp to gain the largest benefit?

Thanks,
Ed

 

[Paul Joppa]

What I would do depends on the speakers and listening habits. If there's a lot of loud deep bass - symphonic, electronic, organ music etc. - and the speakers are less than (say) 93dB efficient, then I would probably put a capacitor at the input RCAs, to prevent that deep bass from muddying the mids and treble. I'd use a cap of the same quality as the interstage coupling cap; I might even upgrade both caps since their colorations will add. If the corner frequency were much higher than 70Hz, I'd do this regardless of the music.

Regular bass such as rock, jazz, popular music etc. does not have that much energy below 70Hz so there is little to gain from protecting the driver. In that case I would just swap out the interstage cap as PB suggested.

IMHO, it's important to look at the context of a system when choosing the best design. At least since the Industrial Revolution, western civilization has tended to over-emphasize analysis of a component and under-emphasize balance among all the components. IMHO.

 

[ebag4]

Thanks PJ, I should have told the complete story to begin with, my apologies.  The speakers that will be powered by the Kaiju are 94dB efficient.  The bottom half of the speaker is comprised of a pair of 12" servo subs per channel, each with its own plate amp, in OB "H" alignment, they are designed to play to 200Hz. 

I play a little of everything but classical, including a little rap when my son comes home from school.  Primarily classic rock and blues.

Based on your comments above, it sounds like you recommend adjusting the value of the coupling cap in my situation, what value capacitor would I use with that configuration for a -3dB of 70Hz?

Thanks again,
Ed

 

[Paul Joppa]

I get 0.00913uF. It's not very critical because the slope is very low (6dB/octave) so I think you would be fine with 0.0082 or 0.01uF. 600v or higher rating.

But if you want to be precise, change the 249K resistor Rg to 226K and use 0.010uF, preferably 2% or better.

 

[ebag4]

I get 0.00913uF. It's not very critical because the slope is very low (6dB/octave) so I think you would be fine with 0.0082 or 0.01uF. 600v or higher rating.

But if you want to be precise, change the 249K resistor Rg to 226K and use 0.010uF, preferably 2% or better.

Excellent, thanks Paul.

Best,
Ed