Paramour dual transformer upgrade advice?

[njcanuck]

Hi All,

Bottlehead newbie here.  A few months ago, I acquired a pair of early Paramour mono blocks set up for 2A3s.  Unfortunately, they arrived a little bent out of shape so I

[Paul Birkeland]

Are the dual transformers the Speco T-7010?

I'd opt for the SEX iron upgrade, and use the BCP-15 as the plate choke, while putting the PC-2 in as a power supply filter (use black/blue wires, leave the red disconnected).  There will be a little extra power supply drop (10-15V), but still sufficient operating voltage.

-PB

[njcanuck]

Hi CP,

Thanks for the response.

I believe these Paramours were originally built in Feb. 2001 and the mod to dual transformers dates back to early 2002 so I strongly suspect these outputs are the original Specos.  They have been painted black so it's difficult to confirm.  They are quite small with the wires coming directly out of the windings (no terminal strip). BCP-15s are already installed as plate chokes.  Is the PC-2 a choke? There is a choke already in the power supply but it only has two black wires - also painted black so no identification - PC-2 or maybe something earlier?

[Paul Birkeland]

The T-7010 will have tons of wires poking out of it, I think 4-5 on one side and 3 on the other.  Underneath the chassis, they will be a rainbow of different colors.  The other choke on the chassis is the venerable C7-X, which is 10H at 90mA.

The PC-2 is the Bottlehead plate choke that comes with the iron upgrade.  It is a vastly superior plate choke to the C7-X, but probably similar to the BCP-16.  It does, however, have flying leads, which makes it easier to mount up top.

-PB

[njcanuck]

Yup, a ton of wires in every color!  Well, two tons since they're dual, LOL.  Gotta be T-7010s.  The PS choke must be a CX-7 (wired to the + side of both caps).

Ok, I think I've got it:  Swap the Speco T-7010s for the SEX/Stereomour outputs and replace the CX-7s with the PC-2s.  Leave the BCP-15s on the plates.

Any comments on expected changes in sound?

[Paul Joppa]

You should see a little more headroom in the deep bass.

Check the parafeed capacitor, it should be around 5uF - though the range 2.5uF to 10uF is pretty decent territory. Stick with 600v rating or greater.

[njcanuck]

Currently using a Sonicap 4uF 600V for the parafeed and a RelCap RT .1uF 600V for coupling.

Hmm, mostly bass improvement, huh.  The Hornshoppe speakers don't produce much below 50HZ, so already using SS bass augmentation down there.  Gotta cogitate on this.

Have to say that these little amps are really charming me!

[Paul Joppa]

If you are using an actual crossover, removing bass from the main amps while adding a sub, then you don't need deep bass capability in the main amp.

But if you are feeding full range to the mains, and just adding bass with subs, you WILL hear the difference. Just because the speakers don't reproduce the deepest bass, does NOT mean the amp won't "crunch up" when called on to supply it. Said another way, the speaker may not reproduce the deep bass, but it still absorbs electrical power in the deep bass. If the amp can't supply that power, it will become nonlinear and produce distortion at all frequencies.

I don't know if that's clear - hardly anybody in the broader web community seems to understand this distinction.

[2wo]

Wow, I never though about that.

That's good lesson. Thank you...John

[njcanuck]

Yup, that's pretty clear. And I wasn't thinking of it.  I'm not currently filtering low freqs from the amps, they are running full range.

Hmmm, thinking harder . . .

[Grainger49]

Could he just create a high pass filter at the input?  Say one high quality capacitor feeding the input resistor for each channel?

[Paul Birkeland]

Could he just create a high pass filter at the input?  Say one high quality capacitor feeding the input resistor for each channel?

This is a very good idea.  The 0.1uF/249K coupling cap/grid leak combination could be changed to create a first order highpass filter.

-PB

[njcanuck]

Good info - thanks.

Currently leaning towards upgrading the outputs (via the SEX kit) and it seems they will work well with the BCP-15s as the plate chokes.

Not sure what advantage there is to be gained by replacing the CX-7s in the power supply with PC-2s?

[Paul Birkeland]

It's more that the plate chokes and output transformers come together, and it would be a shame to waste those PC3's.

[njcanuck]

I received the Stereomour output transformers (OT-2) this weekend.  Thanks Eileen!

I think I've figured out that terminals 5 & 10 are the primary but am lost as to the secondary.  Can some kind soul point me to the correct terminal configuration for 8 ohm secondary (I guess 4 ohm would be useful, too).

Thanks!