Help in picking out a tube pre?

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FullRangeMan

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Re: Help in picking out a tube pre?
« Reply #40 on: 12 Aug 2019, 06:39 am »
Too much transcondutance is a prob too little transcondutance also.
Usually tube amp designers choose a input tube by gain or mu in 3 flavors small 20-30x, medium 40x or hi gain 80-100x according the gain they need to boost the input signal, they dont choose by the sound quality.

Its not mandatory a tube be low, mid or hi mu to have good sound or be suited for a such hi-end preamp or amp, what is mandatory are your speakers have to be hi sensitivity as 100dB for allow you use a sweet sound small tube amp, that also are cheap. Low electric efficiency speakers are a PITA to listening they are slow and usually have a evil xover.

According to the great Gizmo (Harvey Rosenberg) the more power has the amp, the worse the sound, and I might add the more powerful the amp more expensive, big and heavy.

I like 6DJ8 family they are cheap in Russia and are plenty of subs:
6N1P 6N2P 6922 6H30 6DJ8 7DJ8 7308 PCC88  ECC88  E88CC  E288CC  6N1 6H23P-EB, Siemens 8223  GA7  CV5358 5670

I dont like 12AX7 family but Chinese manufacturers love it for input power amp and phone stage applications it provide 100x gain is one tube and this tube is made by various sino brands, but for me this tube cost me $30+ship+100% customs duties each, not $3usd as a military Russian 6N1P(6DJ8) or 6H8C(6sn7).

Also 6SN7 is a great sound tube and a reference in linearity and more powerful than any 12AX7.
http://www.gstube.com/catalog/?key=6922&submit=Find

« Last Edit: 12 Aug 2019, 08:04 am by FullRangeMan »

FullRangeMan

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Re: Help in picking out a tube pre?
« Reply #41 on: 12 Aug 2019, 08:03 am »
The famous Joule-Electra OTL power amps used 5 input tubes!
And yet have good sound so if a low gain or hi gain tube is better or worse is not a reliable statement since the music signal will be modeled by the whole circuit.

poseidonsvoice

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Re: Help in picking out a tube pre?
« Reply #42 on: 12 Aug 2019, 11:19 am »
FRM,

Quote
I like 6DJ8 family they are cheap in Russia and are plenty of subs:
6N1P 6N2P 6922 6H30 6DJ8 7DJ8 7308 PCC88  ECC88  E88CC  E288CC  6N1 6H23P-EB, Siemens 8223  GA7  CV5358 5670

That's inaccurate. There are plenty in that list that have nothing to do with the 6DJ8 family. The 6N2P is a 12AX7 substitute. The 6N1P is a completely different design as is the 6H30, 5670, etc...

They might be 9 pin tubes but they are not interchangeable with respect to design criteria and particularly heater current as well.

Best,
Anand.

FullRangeMan

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Re: Help in picking out a tube pre?
« Reply #43 on: 13 Aug 2019, 11:34 am »
FRM,

That's inaccurate. There are plenty in that list that have nothing to do with the 6DJ8 family. The 6N2P is a 12AX7 substitute. The 6N1P is a completely different design as is the 6H30, 5670, etc...

They might be 9 pin tubes but they are not interchangeable with respect to design criteria and particularly heater current as well.

Best,
Anand.
I pick-up this subs list in various tube vendors site, I will try check.
The 6N2P is the hi gain version of the 6N1P, other parameter are the same, both are 6V and recommended as subs by some amp builders including Decware.

6N1P/6N2P filament are both 6 Volts,
12AX7 family filament are 12V.
I could like to see this change(not in my amp of course) it will made nice fire works.

sunnydaze

Re: Help in picking out a tube pre?
« Reply #44 on: 13 Aug 2019, 12:51 pm »
Dehavilland Mercury w/ remote, well under OP's $3k budget.

No personal experience, but have read consistently great things about it over the years.

https://www.usaudiomart.com/details/649542339-dehavilland-mercury-3-tube-preamplifier-with-remote/

(no affiliation with seller)

flavo

Re: Help in picking out a tube pre?
« Reply #45 on: 13 Aug 2019, 02:53 pm »
I picked up a rogue super 99 with the 6sn7 tubes. Got it for $1K so I couldn't pass it up.
There is a beautiful Canary pre for 2300 on USaudiomart that I almost bought. The owner bought it and basically never used it.
But  please the conversation going. This is really useful info.

sunnydaze

Re: Help in picking out a tube pre?
« Reply #46 on: 13 Aug 2019, 03:04 pm »
That's a great price for that preamp!   

Congrats and enjoy!    :thumb:

JakeJ

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Re: Help in picking out a tube pre?
« Reply #47 on: 14 Aug 2019, 01:04 am »


I like 6DJ8 family they are cheap in Russia and are plenty of subs:
6N1P 6N2P 6922 6H30 6DJ8 7DJ8 7308 PCC88  ECC88  E88CC  E288CC  6N1 6H23P-EB, Siemens 8223  GA7  CV5358 5670


FRM,

That's inaccurate. There are plenty in that list that have nothing to do with the 6DJ8 family. The 6N2P is a 12AX7 substitute. The 6N1P is a completely different design as is the 6H30, 5670, etc...

They might be 9 pin tubes but they are not interchangeable with respect to design criteria and particularly heater current as well.

Best,
Anand.

Phew! Thank you, Anand!  Misinfomation like this could result in equipment failure.  Be very careful about tube substitutions.  I'm sorry to say I wouldn't take the word of a tube seller as gospel because they want to sell tubes!

Here is a tube data sheet web source that is much more accurate on substitutions.

FullRangeMan

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Re: Help in picking out a tube pre?
« Reply #48 on: 14 Aug 2019, 04:45 am »
Phew! Thank you, Anand!  Misinfomation like this could result in equipment failure.  Be very careful about tube substitutions.  I'm sorry to say I wouldn't take the word of a tube seller as gospel because they want to sell tubes!

Here is a tube data sheet web source that is much more accurate on substitutions.
Nice you came in rescue of your compatriot friend and his 6/12V mischap but this http://tdsl.duncanamps.com/ face page link you posted show no evidence.

This are some partial subs info I get now:
http://www.mif.pg.gda.pl/cgi-bin/vs4.pl

http://www.mif.pg.gda.pl/cgi-bin/vs4.pl

https://www.radiomuseum.org/tubes/tube_6dj8.html

https://www.radiomuseum.org/tubes/tube_6922.html

http://www.gstube.com/catalog/?key=6922&submit=Find

http://www.gstube.com/catalog/?key=6dj8&submit=Find
« Last Edit: 14 Aug 2019, 06:19 am by FullRangeMan »

JakeJ

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Re: Help in picking out a tube pre?
« Reply #49 on: 15 Aug 2019, 03:54 pm »
Nice you came in rescue of your compatriot friend and his 6/12V mischap but this http://tdsl.duncanamps.com/ face page link you posted show no evidence.

Apologies.  I figured it was intuitively obvious one click on the "Tube Data" link which opens the tube search engine.  Enter the desired tube type, click on the tube from the results, a list of subs is provided.  Here is the list provided on the 6922:    6922WA, CCA, CV10320, CV2492, CV2493, CV8065, E88CC, E88CC01, ECC868
Different rating or performance   6DJ8, 6N23P*, CV5358, ECC88.  Linky  Note the 6H30 is not in this list.  The 6922 heater draws 0.3A and the 6H30 draws 0.9A, fairly substantial.

Quote
This are some partial subs info I get now:
http://www.mif.pg.gda.pl/cgi-bin/vs4.pl

http://www.mif.pg.gda.pl/cgi-bin/vs4.pl

https://www.radiomuseum.org/tubes/tube_6dj8.html

https://www.radiomuseum.org/tubes/tube_6922.html

http://www.gstube.com/catalog/?key=6922&submit=Find

http://www.gstube.com/catalog/?key=6dj8&submit=Find


The first two links don't work for me.

The third and fourth references the Radio Museum and both state clearly"Multiple differences or of other kind:"

Then the GSTubes website it states the equivalents are 6922 and 6DJ8 which are not eqivalents on tsdl and Radio Museum.

Unfortunately your own references are in conflict.  I have spoken at length with Andy at VTS and he agrees with the info I refer to.

I am not trying to incite a battle here so I will close with, we must agree to disagree.

However, I do fully agree a person should consult the manufacturer for correct tube substitutions.

mhconley

Re: Help in picking out a tube pre?
« Reply #50 on: 15 Aug 2019, 05:32 pm »
Not much info out there on this line stage, so I struggled to understand the layout and what each tube does in the circuit.

Tubes are lined up 6 across:

  1        2          3          4           5            6
5687  12au7   12au7   12au7   12au7     5687

(tubes 2 thru 5 are 12at7 in earlier version of the YS Audio / Audio Experience Balanced A2 preamp)

My understanding is that they work in L and R pairs, so 3 pairs.  So the 2 middle ones (tubes 3 and 4) are a L R pair and do the same thing in the circuit and therefore must be a matched pair.  Moving to the outside in each direction, tubes 2 and 5 are a L R pair working together in the circuit and must also be a matched pair, but not necessarily identical to the prior pair.

From this review I learned that the 2 pair of 12au7 do the gain, and the 5687 is the output buffer.

http://www.enjoythemusic.com/magazine/equipment/0910/ys_audio_audio_experience_a2_se.htm

But this always confused me......
If you check the specs on the mfr website you will see that the XLR outputs give 20 db of gain for both SE and XLR inputs, while the SE outputs give only 4 or 14 db of gain (varies depending on whether SE or XLR inputs are used).
And this is at odds with the review referenced above which says gain is 17db at XLR outputs and 12db at SE outputs.
Anyone have any insight?

I used 2 different pair of 12at7 simply because I didn't have 4 of the same, and I figured (guessed?) it was safe to do so.    :dunno:

My guess is that you can safely use different tube pair combos to shape the sound and achieve different sonic landscapes and synergies.

I recently purchased a pair of 300b PSET monoblocks and got the urge to do a little tube rolling in my A2. I bought a quad of Mullard m8162 for the 12AAT7 and a pair of Sylvania 7119 for the 5687. Also looking at another pair of 5687. I’ll probably end up selling what I don’t keep.

Martin

sunnydaze

Re: Help in picking out a tube pre?
« Reply #51 on: 15 Aug 2019, 09:39 pm »
I recently purchased a pair of 300b PSET monoblocks and got the urge to do a little tube rolling in my A2. I bought a quad of Mullard m8162 for the 12AAT7 and a pair of Sylvania 7119 for the 5687. Also looking at another pair of 5687. I’ll probably end up selling what I don’t keep.

Martin

Nice!   :thumb:

I've loved any NOS Mullard I've ever tried.

I was mistaken earlier.....
I recently checked mine, I have a quad of NOS Mullard CV4024 in the 12at7 positions.

For the buffer pair I think it's NOS GE 5687, maybe Tung-Sol.

FullRangeMan

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Re: Help in picking out a tube pre?
« Reply #52 on: 16 Aug 2019, 02:57 am »
Sorry the Mif link Jake, try this one and type 6922 or 6DJ8:
http://www.mif.pg.gda.pl/homepages/frank/vs.html
it will show some equivalent, a side in my list some tubes are direct subs, others only similar, in any case the amp owner must consult the amp builder as usually the amp circuits are compatible with 2 or 3 tube models only.
http://www.mif.pg.gda.pl/homepages/frank/vs.html
I dont remember why I add the expensive 6H30 to this list :o