Need the knowledge please!

Ok....now that I know I have 12AX7 that are NOS Sovtek in the L and R slot, which I assume are the right and left outputs, I have also a single tube off to the side...odd position in my preamp. its a 12AU7 that has China written on it, so I pretty much know its a nice sounding tube.

A friend of mine from Audiokarma sent me a 12AU7 Tulefunken which I plugged into the odd position and took out the cheap China tube. Man... voices and midsection seem to have opened up and voices are more pronounced, and the overal sound seems more lush.... And this from changing out the odd position tube for a brand name Tulefunken!

So what is each tubes job in the L,R,, and odd positions any way? Am I right in assuming the L, = left, and R=right..? IF so what is the odd tubes job? Thanks.

I don't have the schematic of your amp, but I do have a 1959 copy of the RCA receiving tube manual.

The 12au7 ia a miniature (9 pin) dual triode so it could indeed be in the signal path of both the right and left channels. It replaced the 6SN7, an octal (8 pin) tube of similar design.

Example...

Frenchy lots of preamps wil have a final stage which the signal will go through. My EICO has a pair for each channel and then a fifth tube which it all filters through. What it means is that you can have more fun manipulating the tone. I often switch out this fifth tube between a Mullard and a Psvane. I am done rolling for now, so enjoy and hopefully you will find the perfect combo.

Oh...thanks fellas for the knowledge...I get it now. And yes Pops....I will be replacing the left and right tubes, but not right now. The 2 Sovtek with the Tulefunken aint bad at all.

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Originally Posted by frenchmon

And this from changing out the odd position tube for a brand name Tulefunken!

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Only the tube in front is for the power supply. Most small tubes are of the dual triode design so one tube can function with both channels. Only a schematic would tell you the exact role. Perhaps it is the output buffer. The primary difference between 12AU7, 12AT7 and 12AX7 has do with gain with the "X" having the highest. My Manley DAC uses a pair of 12AU7s for its analog output where I use RCA cleartops.

rw

I used to play in bands years ago and have a lot of friends that still do and most of my guitar player friends have tube heads(amps,preamp combos) from different manufacturers like Marshall, Mesa Engineering, Peavey ETC. and all of them that take their playing seriously keep different tubes around for both the preamp stage(12ax7, 12au7,ETC) and power tubes(6l6, EL84,EL34,ETC) depending on what their amps can use and bias too and what kind of sound and power they are looking for. Most of their decision making is based of the type of music they are going to play from hard distorted music to clean slower stuff and they will drastically change the sound character of their amp setup by changing out the tubes, Now most of these guys took the time to study the design of their amps and learn what to do and what not to do as far as biasing and which tubes to use together and what not, you see where I am going with this. It does take knowledge to be able to do this but there are guys on here that know and there is a lot of information in books and online on this subject. I suspect it is very obvious that home audio components are the same as guitar amps in that the brand, type of make and type of tube can have a dramatic effect on the sound quality and sound character of any piece of tube equipment whether it be a tube preamp like you Vincent or a tube power amp like Mr. Peabody's CJ's. I would just do some studying and looking around at other owners of that particular preamp to see what does in fact work best and also to get the kind of sound you are after as well.

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Originally Posted by E-Stat

Only the tube in front is for the power supply. Most small tubes are of the dual triode design so one tube can function with both channels. Only a schematic would tell you the exact role. Perhaps it is the output buffer. The primary difference between 12AU7, 12AT7 and 12AX7 has do with gain with the "X" having the highest. My Manley DAC uses a pair of 12AU7s for its analog output where I use RCA cleartops.

rw

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Well I dont have a schematic and would not know where to get one.
On the board itself there are 4 tubes. The very first one up front is for the power supply and does not go through the signal path. Then you have two tubes one in front of the other. one says "L" the other says "R" and they are 12AX7 tubes for both slots. Then you have the odd tube off to the left side thats the 12UX7...this is the tube I assume is the output tube?

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Originally Posted by harley .guy07

I used to play in bands years ago and have a lot of friends that still do and most of my guitar player friends have tube heads(amps,preamp combos) from different manufacturers like Marshall, Mesa Engineering, Peavey ETC. and all of them that take their playing seriously keep different tubes around for both the preamp stage(12ax7, 12au7,ETC) and power tubes(6l6, EL84,EL34,ETC) depending on what their amps can use and bias too and what kind of sound and power they are looking for. Most of their decision making is based of the type of music they are going to play from hard distorted music to clean slower stuff and they will drastically change the sound character of their amp setup by changing out the tubes, Now most of these guys took the time to study the design of their amps and learn what to do and what not to do as far as biasing and which tubes to use together and what not, you see where I am going with this. It does take knowledge to be able to do this but there are guys on here that know and there is a lot of information in books and online on this subject. I suspect it is very obvious that home audio components are the same as guitar amps in that the brand, type of make and type of tube can have a dramatic effect on the sound quality and sound character of any piece of tube equipment whether it be a tube preamp like you Vincent or a tube power amp like Mr. Peabody's CJ's. I would just do some studying and looking around at other owners of that particular preamp to see what does in fact work best and also to get the kind of sound you are after as well.

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Oh yeah...I hear ya Harley loud and clear. I've already seen how one tube can change the sound by changing out the cheap China tube for a much better one....with the switch, for the Tulefunken, sound of the Vincent has yielded a much more luxurious sound.

Sovtek makes decent entry level tubes. I tried a pair of Sovtek's 2a3 in my Dared but they were totally out classed by the stock 2a3 Shuguangs which are not top performers.

I've got a pair of Fisher labeled Telefunken 12AX7's in my tube cd player that would take your preamp to another level. The NOS are costly but used ones that test well are affordable. Telefunkens can have a variety of labels but they must have the diamond between the pins to be the real deal.

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Originally Posted by Poultrygeist

Sovtek makes decent entry level tubes. I tried a pair of Sovtek's 2a3 in my Dared but they were totally out classed by the stock 2a3 Shuguangs which are not top performers.

I've got a pair of Fisher labeled Telefunken 12AX7's in my tube cd player that would take your preamp to another level. The NOS are costly but used ones that test well are affordable. Telefunkens can have a variety of labels but they must have the diamond between the pins to be the real deal.

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Ok....Poultry...thanks for the knowledge.

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Originally Posted by frenchmon

On the board itself there are 4 tubes...

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Pics of the internals were easy to find on Google. It was based upon looking inside that I made my comments.

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Originally Posted by frenchmon

Then you have the odd tube off to the left side thats the 12UX7...this is the tube I assume is the output tube?

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Well, the output buffer to reduce the output impedance. All three tubes are part of the output stage. They are likely using one half of the 12AU7 for each channel.

rw

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Originally Posted by E-Stat

Pics of the internals were easy to find on Google. It was based upon looking inside that I made my comments.


Well, the output buffer to reduce the output impedance. All three tubes are part of the output stage. They are likely using one half of the 12AU7 for each channel.

rw

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Estat...can you tell if its a hybrid pre or not? I've seen reports that say its a hybrid and I've seen reports that say its not. I have the manual for both the SA-T1 and the matching mono power amps SPT - 100. It list the SA-T1 as valve and the SPT - 100 as the hybrid, valve transistor.

Thanks

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Originally Posted by frenchmon

Estat...can you tell if its a hybrid pre or not?

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It sure looks like they're only using tubes in the signal path. You can follow traces on the circuit board from the 12AU7 to the blue output coupling capacitors to the output jacks.

There are some solid state regulators towards the front on heat sinks and there appears to be a handful of FETs towards the back left part of the circuit board, but they appear to be power supply related.

rw

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Originally Posted by E-Stat

It sure looks like they're only using tubes in the signal path. You can follow traces on the circuit board from the 12AU7 to the blue output coupling capacitors to the output jacks.

There are some solid state regulators towards the front on heat sinks and there appears to be a handful of FETs towards the back left part of the circuit board, but they appear to be power supply related.

rw

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Ok thanks. My dealer who gave me an unbelievable price on it...way below the last listed price said it was not a hybrid. Vincent does not list it as a hybrid either. But I assume because the SPT - 100 is a hybrid, most think that the SA-T1 was one as well. But that's not the case...thanks E-stat for the knowledge.

Do they make tube preamp hybrids? If so why? :-)

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Originally Posted by Poultrygeist

Do they make tube preamp hybrids? If so why? :-)

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Dont know Poultry....but you are welcome to call up a few manufactures and ask them that same question.

I can understand a tube hybrid amp which has the power of solid state but with a tube preamp stage.

What advantage could there be to having a tube and transistor mixed pre stage? Would it be for someone who is only partially sold on the tube sound?

From what I have read through literature from Vincent and other companies that sell hybrid preamps is that their belief is that by making a hybrid preamp they can get the midrange benefits and warmth of tube gear but also get the detail and bass slam from the solid state components and have a high end that is not rolled off like some tube gear is. To some degree I see where they are coming from but in practice I am not sure how well it works because I have not had the chance to hear any hybrid gear but Frenchmon seems to like his Vincent over his Rotel so its doing something right.

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Originally Posted by Poultrygeist

I can understand a tube hybrid amp which has the power of solid state but with a tube preamp stage.

What advantage could there be to having a tube and transistor mixed pre stage? Would it be for someone who is only partially sold on the tube sound?

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Good question. I know a guy over on Audiokarma who has a hybrid preamp. He says its the best preamp he has ever had. Next time I'm over there I will ask him. My guess it would have the same effect if there was a SS amp.

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Originally Posted by harley .guy07

From what I have read through literature from Vincent and other companies that sell hybrid preamps is that their belief is that by making a hybrid preamp they can get the midrange benefits and warmth of tube gear but also get the detail and bass slam from the solid state components and have a high end that is not rolled off like some tube gear is. To some degree I see where they are coming from but in practice I am not sure how well it works because I have not had the chance to hear any hybrid gear but Frenchmon seems to like his Vincent over his Rotel so its doing something right.

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Hi Harley...

My dealer said the SA-T1 was not hybrid....the SA-T1 manual says its all tube and E-Stat confirmed that its all tube and not hybrid. But yes...this thing is a few steps above the Rotel preamp which in its self is a very good SS preamp.. Its the Rotel RC 1090. If you have a chance to get one used grab it if you need one.

The only reason why the Rotel preamp is still in my system now is because I run the 7.1 in through its phono stage and out into the SA-T1. The Rotels phono stage is very good.

And yes...by the SA-T1 being tube and the Rotel amp RB 1080 being SS, I have the warmth of tube with nice detail and bass slam with no noticeable roll off. I can tell you from experience and memory....SS is a cleaner sound but after listening to tubes you dont even notice it or miss it....at least that's my recollection.

But I can also tell you....Peabodys All valve Conrad Johnson amp/preamp has great detail and bass slam as well. Its really warmer than I would like...and that could because of the stock tubes that Peabody refuses to roll, but never the less....that thing has detail and slam....so one does not have to get hybrids or have a hybrid system as mine in order to get detail and bass slam from tubes. But I'm sure you know what I'm talking about...you've heard Peabodys system. Hey one day Sunday before winter hits....maybe you can come up to Peabodys and I can bring over the SA-T1 and plug it into Peabodys system or we maybe able to come down your way? I will get with Peabodys and see what he wants to do...Let us know if you want to come up or if it will be better to come your way. I think Springfield is about 1 1/2 hours drive?

That would be cool either way. I think some weekend I could come up there when I get a good break form school that I am not studying or doing work, but you guys could come down as well its really up to you, the drive is actually not bad at all so it does not bother me. I thought that model of Vincent was a Hybrid but I stand corrected. I do know that Vincent makes some Hybrid stuff but that might be in their power amps.
I studied for a while before getting the good deal on my NuForce pre, I am not sure if you have heard one but if not maybe I could bring it just to do some comparing since it is in a whole different category since it is not typical SS, and it is not tube, being class D it might bring some things to the table that the others don't and vice versa. I think it would be fun to get these pres together just for the fun of hearing the difference in them since they seem to be around the same price class retail. By the way Mr. Peabody E Mailed me the other day and told me that he is going back to his Dynaudio 2.5t's since he missed the control and detail of the Dyn's and also the detailed bass that the Zu Omens just could not give him which is weird seeing that the Omens have two 10" per cab. He said he would miss the openness of the Omens but they just seemed to lack low end and the cotrol of the Dyns. That is something I would like to hear for myself seeing the rave that Zu have been getting lately. But I also see a lot of them for sale on audiogon after the owners only having them a few months so there must be something fatiguing about them.

Wow that is big news. I thought Peabody was sold on the Zu's and we would see his 2.5's show up on Audiogon. We've missed old P here these last few months. Thanks for the update.

Yeah he has expressed the concerns with me about the Zu's as well. When he first had them hooked up that first week I was over and told him not to many manufacturers do the bottom end like Dyns....that he would sacrifice the bottom of the Dyns for a more open sound. He decided to go with the Zu...to which in my opinion is really not in the class of Dyns....and seems like a fad that is now fading. He tried it for a few months and decided its not really for him seeing he likes for his bass to hit him in the chest. To get the bottom end slam he wants along with the open airy sound he also likes, he is going to have to spend some cash to find it...like some Canton Reference 3.2 DC speakers or even some Focus Audio FP 88 SE...both speakers will give him the slam he wants and still maintain the open air he desires.

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Originally Posted by harley .guy07

From what I have read through literature from Vincent and other companies that sell hybrid preamps is that their belief is that by making a hybrid preamp they can get the midrange benefits and warmth of tube gear but also get the detail and bass slam from the solid state components and have a high end that is not rolled off like some tube gear is. To some degree I see where they are coming from but in practice I am not sure how well it works because I have not had the chance to hear any hybrid gear but Frenchmon seems to like his Vincent over his Rotel so its doing something right.

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Harley, I can tell you that after getting to do an in home audition of all three Van Alstine preamps- SS, Tube and HYbrid that the hybrid does do the best of both worlds. The hybrid has the most air, transparency with a smooth, warm midrange, good bass and treble with no roll off. The SS had the best bass and the Tube had the most warmth but the Hybrid had the best sound. Tube rolling let you fine tune the sound to your liking though.

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Originally Posted by Poultrygeist

I can understand a tube hybrid amp which has the power of solid state but with a tube preamp stage.

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It is very expensive to get truly low noise high gain tube preamps, especially where phono is concerned. The Audio Research REF40 uses eight tubes for a line stage while Conrad-Johnson uses ten tubes in the ART line stage. Add another four for a phono stage.

By contrast, I have a hybrid Audio Research preamp that provides 67 db of gain with only two stages and is dead quiet. It uses an FET front end with a single tube follower for each of the phono and line stages. Works great with MC cartridges without having to add a transformer or pre-preamp stage.

rw