Meier Audio Corda Eartube eye candy,Yummy.
Nov 15, 2004 at 3:24 AM Post #31 of 66

sacd lover

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Quote:

Originally Posted by kevin gilmore
Both the 6n3p and the gu17 are russian tubes.
The western electric 396 is a great (and possibly better) substitute
for the 6n3p, but i can't find a suitable substitute for the gu17.

This looks to be a very sweet push pull couple watt transformer
output amplifier.

Getting replacement tubes in the USA could be a bit of a problem.



The 6n3p=we396=5670=2c51. The Russian version, from my research, has QC problems and poor section matching. Supposedly, the tube is better if it was made prior to 1996. If made after 1996 the quality is reportedly very low.The best bet may be to hunt up some of the above mentioned nos variants.

I havent found anything on the gu17 except that the tube is a beam-power double tetrode. I cant find any mention of the tube being used for audio but it is used for RF power amplification.
 
Nov 15, 2004 at 3:47 AM Post #32 of 66

sacd lover

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The 6n3p nos variants are ($5-6) very inexpensive, except for the we396, which I found from one seller for $22 each. Even the we396 is nowhere near expensive as good 6sn7's, 12ax7's etc. The gu17 doesnt seem to have an equivalent so you will be forced to use only that tube. Tetrodes dont have the reputation as having the same high quality sound as triodes; so it will be interesting to see how good the Eartube sounds.
 
Nov 15, 2004 at 8:32 AM Post #33 of 66

Jan Meier

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Dear Headfellows,

According to Audio Valve equivalents for the GU17 are the QQE03/12, the RS1023, and the 6360!

First listening impressions:

More neutral than the RKV. Actually, on first listening this amp is remarkably close to the PREHEAD MkII SE. Not bad at all!

:)

Jan
 
Nov 15, 2004 at 8:47 AM Post #34 of 66

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Quote:

Originally Posted by Jan Meier
Dear Headfellows,

According to Audio Valve equivalents for the GU17 are the QQE03/12, the RS1023, and the 6360!

First listening impressions:

More neutral than the RKV. Actually, on first listening this amp is remarkably close to the PREHEAD MkII SE. Not bad at all!

:)

Jan



So perhaps it will be like the Stealth, a tube amp that doesn't forgo the performance of solid-state while adding just a touch of tubey goodness, at a much lower price for those of us not able to climb Mt. Samuels
biggrin.gif
 
Nov 15, 2004 at 12:05 PM Post #35 of 66

sacd lover

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Quote:

Originally Posted by Jan Meier
Dear Headfellows,

According to Audio Valve equivalents for the GU17 are the QQE03/12, the RS1023, and the 6360!

First listening impressions:

More neutral than the RKV. Actually, on first listening this amp is remarkably close to the PREHEAD MkII SE. Not bad at all!

:)

Jan





I found some 6360's online for $6-7. This amp is going to be really inexpensive to retube.
cool.gif
 
Nov 15, 2004 at 12:38 PM Post #36 of 66

kevin gilmore

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The 6360 is indeed a suitable replacement. So are 8457's and 8458's.
Without access to my tube books, these are unique enough that i don't
remember them.

What i can't tell from the pictures is whether or not there are
the 2 extra wires on the output transformers that would allow this
thing to be "ultra linear". Would be sweet if the extra taps were there.

What would be even sweeter is an extra set of windings to do
cross coupled cathodes, but that would require a different output tube.

Each transformer should be rotated 45 degrees. Then the back
panel will look symetrical. There may not be enough room for that
however.

This amplifier is going to sound significantly different from all of the
otl amps currently made (SP,RS,Woo...). Different harmonic structure
entirely. Think dynaco stereo 70.
 
Nov 15, 2004 at 1:01 PM Post #37 of 66

Anders

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Quote:

Originally Posted by Jan Meier
Dear Headfellows,


More neutral than the RKV. Actually, on first listening this amp is remarkably close to the PREHEAD MkII SE. Not bad at all!

:)

Jan




This is promising for those who want a tube amp that leans toward a neutral sound rather than euphonic. My impressions of the Prehead Mk II SE are preliminary although I have listened to it (burned-in) a number of hours on both headphones (HD650/Zu) and speakers. It is a clear step up in relation to the previous Prehead. The previous model is very good but has a slight edginess and brightness that makes it sound SS despite its good qualities otherwise. Mk II SE is much smoother and sounds more liquid and unrestrained. This is not at the expense of detail, on the contrary it is better on separating complex passages and layering of voices and intruments in separate spaces than the previous model. I got most if not all of the advantages of Earmax Pro, but with increased resolution, especially of complex passages.
Maybe Meier Audio now can offer two very good and natural sounding amplifiers where the the main difference is in construction rather than sound?
 
Nov 15, 2004 at 1:36 PM Post #38 of 66

Jan Meier

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Hello Kevin,

"So are 8457's and 8458's."

Thanks for the note.

"Each transformer should be rotated 45 degrees. Then the back
panel will look symetrical."

True, looks would be better. However, according to Helmut Becker this arrangement was choosen to minimize any interaction between transformers. Originally I wanted the power amplifier to be on the back of the amp and the output transformers on the front, but tests showed that this resulted in humm and decreased channel separation.

All your other questions have to be cleared with Mr. Becker. As you will know, I'm not an expert on tube amplifiers at all.

Hello Anders,

"Maybe Meier Audio now can offer two very good and natural sounding amplifiers where the the main difference is in construction rather than sound?"

There certainly are some sonic differences but I haven't done any extensive listenings/comparisons yet. But indeed this new amp is much closer to the CORDA sound than the RKV.

Cheers,

Jan
 
Nov 15, 2004 at 2:01 PM Post #39 of 66

kevin gilmore

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quote
"Each transformer should be rotated 45 degrees. Then the back
panel will look symetrical."


I get that the transformers should be 90 degrees from each other.
But if you rotate BOTH transformers 45 degrees, then they are still
orthogonal to each other, and it looks better...
 
Nov 15, 2004 at 10:24 PM Post #40 of 66

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So is it designed with only high imp. phones in mind, or can I use my low imp cans too?

EDIT: Nevermind, I just re-read Jan's post. So much new information.... Got to go lay down and wait for this nosebleed to subside.
 
Nov 15, 2004 at 10:49 PM Post #41 of 66

Wmcmanus

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What a nice looking product! For anyone on the fence, tubes are the way to go, and when you throw in crossfeed and a reasonable price, wow!
 
Nov 15, 2004 at 11:13 PM Post #44 of 66

Jan Meier

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Dear Kevin,

"I get that the transformers should be 90 degrees from each other."

It's one condition, but enough. One transformer should be placed on the axis of the other one. Plane symmetry is required.

"What i can't tell from the pictures is whether or not there are
the 2 extra wires on the output transformers that would allow this
thing to be "ultra linear"."

I just took a look at the schematics and the transformers indeed have windings to allow for feedback (which is actually used).

"So is it designed with only high imp. phones in mind, or can I use my low imp cans too?"

The amp has output transformers and is able to drive low impedance headphones, but I haven't tried yet so I can't tell you how good it will do.

"So perhaps it will be like the Stealth, a tube amp that doesn't forgo the performance of solid-state while adding just a touch of tubey goodness"

I just did a little bit more listening. I never heard the Stealth myself but comparing to the PREHEAD MkII SE I feel this description fits very well.

Cheers,

Jan
 
Nov 16, 2004 at 1:12 AM Post #45 of 66

kevin gilmore

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Interesting choice of output transformer
http://www.elektrokov.cz/en/products...lded-core.html

I'm sure there is feedback with this amplifier. What i was refering to is
ultra linear.

ULTRA-LINEAR" is a term, when applied to push-pull audio amplifiers, that describes the particular output stage configuration whereby the screen grids (Grid 2) of tetrodes or pentodes are fed from a tapping in each half of the primary of the output transformer - typically 43% turns or 18.5% impedance when measured from the centre-tap, instead of from a DC supply either independent or common to the anodes.

I see no extra taps on the transformers. Still going to be fairly sweet.
Could be as much as 8 watts rms. K1000's might really like this.
 

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