Tube Pre

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Chico Jim

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Tube Pre
« on: 25 Jul 2018, 05:27 pm »
Today I put my Bottlehead Foreplay II back into the system.  It is a highly modified foreplay with shunts, Mundorf

Caps, beefier transformer and set up for 6FQ7 tubes.  It is dead silent and is otherwise a simple passive unit but sounds huge.  The air with it is much better as it feels much thicker and full, yet very detailed.  This is the same pre that replaced my 1961 McIntosh MX-110 several years back.  The MX-110 was completely restored and aligned. It sounded wonderful.

I’m still liking the Yamaha MX-630 amp and simply can’t hear any weaknesses compared to my Audio Research VS-110.  Both are very good.  The Yamaha has more slam which really surprises me, yet it is still very nice in the highs, especially female vocals. 

I prefer my Ah! Tjoeb 99 over the Denon DVD 2930, but both are pleasing to my ears. 


rollo

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Re: Tube Pre
« Reply #1 on: 25 Jul 2018, 07:17 pm »
  Nice. What 6FQ7 are you using. My favorite brand is RCA. Surprised to hear Yamaha has more slam [ SS ? ]


charles

Chico Jim

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Re: Tube Pre
« Reply #2 on: 25 Jul 2018, 07:31 pm »
Clear top RCA’s, but I have some others that I roll now and then, Canadian Westinghouse’s for one. Yeah, me too about the Yamaha, it’s about 200wpc in 4ohm with over 2db of headroom.  Yes, SS from 1992, nothing expensive but sounds very nice.

Chico Jim

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Re: Tube Pre
« Reply #3 on: 25 Jul 2018, 07:39 pm »
Excuse the dust😟




Chico Jim

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Re: Tube Pre
« Reply #4 on: 25 Jul 2018, 10:30 pm »
The obvious answer as to why more slam is that the Yamaha amp has more raw power that allows me to use more of the panels for mid bass and rely less on subwoofers to get proper levels from 60hz and lower. The panels without subs on the Yamaha go down to 40 before falling off.  With the AR VS110, down to 50’ish which is a big amount that was going to the subs.

Chico Jim

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Re: Tube Pre
« Reply #5 on: 25 Jul 2018, 10:35 pm »
Screen shot





mresseguie

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Re: Tube Pre
« Reply #6 on: 26 Jul 2018, 03:12 am »
Hello, Jim.

What do the shunts do? [Shunt power to a third dimension?  :icon_twisted:]

I like tube preamps, but I'm not exactly knowledgeable about all the parts.

Regards,

Michael

oldnuke

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Re: Tube Pre
« Reply #7 on: 26 Jul 2018, 05:24 am »
I have one of those on a shelf in the garage;  the shelf of "things too good to get rid of".  You should go BeePre, it's head and shoulders above the Foreplay...

Chico Jim

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Re: Tube Pre
« Reply #8 on: 26 Jul 2018, 11:38 am »
Hi Michael:

Shunts basically are resistors in passive circuits, in this instance a high quality resistor on the sweep ground lugs of the potentiometers.  Instead of the “pot” carrying the signal, the shunt does which is a shorter and cleaner path.  The results are day and night.  There is also a power supply shunt regulator to keep the current current constant.  Both really keep the pre silent.

Jim

P.S.

Here’s what’s been modded from the original layout:

It has Pseudo dual mono power stage (PDMPS), each signal wire is shielded and has its own ground, done like they did on the Foreplay III , the volume controls are in shunt mode, it has  RRSF which is a filter to take any nasties out of the electricity coming from the wall. It uses Vishay-Dale resistors, which I think sound very good. And finally it has an IEC connector and am using a home brew power cord.

rollo

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Re: Tube Pre
« Reply #9 on: 26 Jul 2018, 05:25 pm »
Clear top RCA’s, but I have some others that I roll now and then, Canadian Westinghouse’s for one. Yeah, me too about the Yamaha, it’s about 200wpc in 4ohm with over 2db of headroom.  Yes, SS from 1992, nothing expensive but sounds very nice.


   Great tubes. Keep the Yamaha at 200W/ch. Liking the Audio Hungary APR 204 with that amp. www.audiohungary.com


charles

Chico Jim

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Re: Tube Pre
« Reply #10 on: 27 Jul 2018, 01:14 am »
Charles:

Nice

Jim

rollo

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Re: Tube Pre
« Reply #11 on: 7 Aug 2018, 06:40 pm »
Clear top RCA’s, but I have some others that I roll now and then, Canadian Westinghouse’s for one. Yeah, me too about the Yamaha, it’s about 200wpc in 4ohm with over 2db of headroom.  Yes, SS from 1992, nothing expensive but sounds very nice.


 Chico Andy at Vintage Tube Service has the best RCA 6FQ7's around.


charles