[Review] Little Dot MK VI - 6SN7GT Brimar CV1988
Sep 4, 2009 at 6:47 PM Thread Starter Post #1 of 14

giuca70

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Hello Head-fier's

Based on many upgrade of MKVI lovers, I write this about upgrade 6SNGT.

My review about my MKVI and 6SN7GT=CV1988 BVA NOS.

Sound of this valve is fantastic, more headstage, more separation, more detail, more music than 6H9C.

4 Raytheon 6080, actually. New upgrade Tung-sol 6AS7 to come...

Sound is very beautiful, wide bass, vocal warm, treeble little back. With Raytheon 6080.

The Headphone: 950ltd, 880 Pro, W-1000, K340. All balanced.
Listen with adaptor SE, sound is impressive. More control in SE with MKVI.
Balanced have more dynamic, SE more control, more defined.

The two modes have their particular features. Both are good.
 
Sep 4, 2009 at 6:55 PM Post #2 of 14

El_Doug

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i find it VERY interesting that youre getting a better sense of control via SE rather than balanced - my experiences with this amp were the polar opposite
biggrin.gif
 
Sep 4, 2009 at 10:26 PM Post #3 of 14

giuca70

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Quote:

Originally Posted by El_Doug /img/forum/go_quote.gif
i find it VERY interesting that youre getting a better sense of control via SE rather than balanced - my experiences with this amp were the polar opposite
biggrin.gif



I think it's because of cv1988, though if this amplifier has greater control and dynamics, when compared with the Russian 6h9c.
This Brimar elevate all parameter of MKVI. Both SE and Balanced.

I have made an adaptor XLR 4-pin --> jack female 6,3 for SE use.
Now, this amp go with Neutrik 6,3mm back.
The idea is common with David. We thought at the same time.
 
Sep 5, 2009 at 8:01 AM Post #4 of 14

cafe zeenuts

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Hey giuca70

Quote:

Originally Posted by giuca70
The Headphone: 950ltd, 880 Pro, W-1000, K340. All balanced.


In your first post you state that all your headphone is balanced, meaning they’re all retermined to 4Pin XLR right???

Quote:

Originally Posted by giuca70
I have made an adaptor XLR 4-pin --> jack female 6,3 for SE use.


In your last post you stated that you have build a SE adapter to listen to single end mode (4pin male XLR -> 6.3mm female stereo jack).

So in order for you to listen your current balanced headphones (4pin xlr) in single ended mode you will have to use a 6.3mm male plug to 4pin female XLR adpater and then connect to the SE adapter (4pin XLR -> 6.3mm female stereo jack). That is a lot of connectors and adapters to listen in Single Ended mode don’t you think???


It’s seem that some of your headphones are low impedance. The LD MK6 IMHO don’t drive low impedance that well. This amp was design driving high impedance phone in mind. In order for low impedance headphone to sound great, build a 4pin xlr 100ohm impedance adapter and try with the LD MK6 and low impedance headphones.
 
Sep 6, 2009 at 8:00 PM Post #6 of 14

HeatFan12

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The 6SN7 can be dropped in, in place of the 6SL7? I thought they were not interchangeable. I have been interested in this amp since it came out, but since I don't have any 6SL7s and did not want to invest in a different family, I lost interest.

I have plenty of 6080/6AS7 and several nice matched pairs of 6SN7s.

Hmmm...

From what I have read-

"The 6SN7 has an amplification factor of 20 and a plate resistance of about 7k, whereas the 6SL7 is 70 and 44k respectively."

I know the pinout is the same, but now I'm wondering..

All of you LDMKVI users never had a problem with the 6SN7 as driver? No adverse effect and so on?

Thanks
 
Sep 8, 2009 at 11:39 AM Post #9 of 14

giuca70

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Hello Heatfan12,
MKVI accept 6H9C/6SL7/6SN7 and all variant with same electrical value and impedance.
MKVI has autobiasing.

Some type of 6SN7 could be 6SN7GT with identical electrical parameter. You could analize schematic of 6H9C with CV1988. This is 6SN7GT equivalent.

Your collection 6AS7/6080 and 6SN7 are welcome to MKVI.

I tried 6SN7GT = CV1988 and sound is beautiful with identical volume.
If You try ECC32 or ECC33, You see ECC32 has less gain than ECC33.
This less gain is no problem for MKVI. MKVI have much power reserve with all headphone impedance.
 
Sep 8, 2009 at 11:50 AM Post #10 of 14

giuca70

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For XLR to SE use, I try back-out XLR 3-pin and front-out 4-pin XLR to SE, and I use R+, L+, ground of XLR 4-pin.

Sound with front-out have more control, both SE and balanced. I think this out have few Ohm impedance (OCL), back-out have 600 Ohm impedance.

Some headphone sound well in balanced mode (650, 880), and other headphone sound well in SE (K340).

But this is personal. For me K340 sound well also in balanced mode with CV1988. I can alternate SE-Balanced, depending of genre of music.

Neutrik connector have gold pin, and I think to made a XLR 4-pin to (XLR-4 pin SE). So I can delete XLR 4pin to SE adaptor with balanced headphone.
 
Sep 8, 2009 at 6:43 PM Post #11 of 14

HeatFan12

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Quote:

Originally Posted by giuca70 /img/forum/go_quote.gif
Hello Heatfan12,
MKVI accept 6H9C/6SL7/6SN7 and all variant with same electrical value and impedance.
MKVI has autobiasing.

Some type of 6SN7 could be 6SN7GT with identical electrical parameter. You could analize schematic of 6H9C with CV1988. This is 6SN7GT equivalent.

Your collection 6AS7/6080 and 6SN7 are welcome to MKVI.

I tried 6SN7GT = CV1988 and sound is beautiful with identical volume.
If You try ECC32 or ECC33, You see ECC32 has less gain than ECC33.
This less gain is no problem for MKVI. MKVI have much power reserve with all headphone impedance.




Hello giuca70

Thanks very much for this information...
 
Sep 13, 2009 at 8:24 AM Post #12 of 14

glitch39

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I have used 6SN7GT on my MkVI from the beginning. Used Tung-sol, GE, RCA, Raytheon, Ken-Rad, CBS, Sylv, you name it. When I had the black plate 6AS7G's on the power side, the best complement was the Raytheon or RCA VT-231's.

I checked with David and he confirmed it not being a problem. The transformers are able to handle the additional current load of the 6SN7. If you have seen the original MkVI design on the LD board, you'd know that it was originally designed around the 6SN7. 6SL7 was used instead on the final design to increase the output.

I stumbled over a REALLY nice power tube for the MkVI - the Sylv 6AS7GA. And matched with Sylv VT-231's. I really like how it sounds now - a lot like my old SP Extreme - bass, power, mids, headroom - got them all.
 
Sep 13, 2009 at 3:49 PM Post #13 of 14

glitch39

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Quote:

Originally Posted by HeatFan12 /img/forum/go_quote.gif
From what I have read-

"The 6SN7 has an amplification factor of 20 and a plate resistance of about 7k, whereas the 6SL7 is 70 and 44k respectively."

I know the pinout is the same, but now I'm wondering..

All of you LDMKVI users never had a problem with the 6SN7 as driver? No adverse effect and so on?

Thanks



6SN7 has higher plate current. David confirmed that the trafo can handle it without issues

6SL7, although having a higher mu on paper, is not driven that high. actually closer to 40 in reality. 6SN7 has an mu of 20. when switching between the two, I have to increase the volume by a notch.
 
Sep 13, 2009 at 8:51 PM Post #14 of 14

HeatFan12

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Quote:

Originally Posted by glitch39 /img/forum/go_quote.gif
I have used 6SN7GT on my MkVI from the beginning. Used Tung-sol, GE, RCA, Raytheon, Ken-Rad, CBS, Sylv, you name it. When I had the black plate 6AS7G's on the power side, the best complement was the Raytheon or RCA VT-231's.

I checked with David and he confirmed it not being a problem. The transformers are able to handle the additional current load of the 6SN7. If you have seen the original MkVI design on the LD board, you'd know that it was originally designed around the 6SN7. 6SL7 was used instead on the final design to increase the output.

I stumbled over a REALLY nice power tube for the MkVI - the Sylv 6AS7GA. And matched with Sylv VT-231's. I really like how it sounds now - a lot like my old SP Extreme - bass, power, mids, headroom - got them all.




Great news...Thanks glitch....
 

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