Which preamp to choose for my ECC88s?

[Andypairo]

Hello,
I've been thinking about making a tube preamp (among the half-million of things in the "to-do" queue), and the only thing that refrained me from building one was the absence of remote control.
Now that I got some ALPS blue motorized potentiometers (50k) I have no more excuses

I've seen two circuits that might fit, the Supertotem from Filippo22's site (here) and the TNT Simpre....

What would you choose? Should I go for the simplest first?
Alternative proposals?

Cheers

Andrea

 

[Eli Duttman]

Hi!

Just my opinion, there are better tubes than the 6922 for building a buffered volume control line stage. The NOS 5687 and the current production ECC99 are 2 examples.

OTOH, the 6922 is excellent in a phono stage, as it's very quiet.

 

[fdegrove]

Ciao Andrea,

Eli is quite right in saying there are much better valves out there for preamp service than the ECC88s.

If you don't know what to use the ECC88s for and happen to have a fair number of them, then sure, you could build a preamp with them.

While I had looked at this so called "Supertotem" variation on an SRPP before, I'm still as unimpressed with it as before.
Why use valves in // when there's absolutely no need for it? What's so special about this circuit that it justifies rebaptising the trusty old SRPP_ in itself a gross misnomer anyway_??
Surely it can sound fine but like all other SRPP variations it's heavily dependent on the quality of the PS.

If you want me to, I could easily come up with a good sounding preamp design using the ECC88 and the 50K ALPS pots. Just let us know what the orderbook looks like....

Ciao,

Frank.

 

[Pjotr]

The NOS 5687 and the current production ECC99 are 2 examples.

Indeed, but is an ECC99 not is bit overdone?

BTW how does the ECC99 compare to the good old 12BH7? Any thoughts or better experience?

I am thinking of replacing my 12BH7’s for ECC99’s in a line-driver stage. Is it worth the effort (and money)?

Cheers

 

[ThorstenL]

Konnichiwa,

I've seen two circuits that might fit, the Supertotem from Filippo22's site and the TNT Simpre....

What would you choose?

Arthur Loesch PSE Linestage if it was for me personally and I'd have to use ECC88, otherwise Supertotem minimal (eleiminate all unneccsary resistors and solve oscillation issues with ferrite beads and/or layout).

Sayonara

 

[fdegrove]

Hi,

Pjotr,

I am thinking of replacing my 12BH7’s for ECC99’s in a line-driver stage. Is it worth the effort (and money)?

Given that both types retail for about the same price nowadays in the EU the ECC99 is to be the prefered type.
It has the better specs of the two:

JJ ECC99

(eleiminate all unneccsary resistors and solve oscillation issues with ferrite beads and/or layout).

Which would be R3, 4, 5 I suppose....
One word of caution while using ferrite beads: use them as close to the grids as possible and glue them into place. Wandering beads is not what you'd want.
Having an o-scope while sorting out oscillatory problems with notorious self-oscillating tubes a la 6C45-P, 6922 and such is a must IMO.

R1, 2, 6, 7 could be replaced with 2 * 550R 1W resistors as well....
After all this surgery the circuit could then again be rebaptised calling it RAPP, as in Regulated Anode Push-Pull, which is what France based Audiomat calls theirs...Nothing new under the sun.


Cheers,

 

[Eli Duttman]

12BH7 vs. ECC99

Something to consider is the difference in mu between the 12BH7 and the ECC99, when common cathode circuitry is employed.

IMO, the ECC99 is the clear choice for cathode follower service, given its high gm.

BTW, don't forget the 6GU7. It's a "6" V. only heater type that's otherwise electrically equivalent to the 12BH7. Jim McShane's price for 6GU7s is 5 USD.

Jim McShane's Site: http://pages.prodigy.net/jimmcshane/

 

[Andypairo]

Re: Re: Which preamp to choose for my ECC88s?

Konnichiwa,

Arthur Loesch PSE Linestage if it was for me personally and I'd have to use ECC88, otherwise Supertotem minimal (eleiminate all unneccsary resistors and solve oscillation issues with ferrite beads and/or layout).

Sayonara

Hello,
where can I find this circuit?
Cheers

Andrea

 

[Andypairo]

Hi!

Just my opinion, there are better tubes than the 6922 for building a buffered volume control line stage. The NOS 5687 and the current production ECC99 are 2 examples.

OTOH, the 6922 is excellent in a phono stage, as it's very quiet.

Hello Eli,
I have 8 Mullard NOS ECC88, and thought they could be a good candidate for a preamp, but it seems they are not "ideal" altough they can certainly work.

About the phono.. no phono no party!

Ciao Andrea,

Eli is quite right in saying there are much better valves out there for preamp service than the ECC88s.

........

If you want me to, I could easily come up with a good sounding preamp design using the ECC88 and the 50K ALPS pots. Just let us know what the orderbook looks like....

Ciao,

Frank.

Ciao Frank,
I understand. What if I can get hold of 2*E82CC (how do they compare with the 5687=182CC ?) and 2* E83CC ?

And Yes, I'd gladly see your proposal for a (line) preamp with the parts I have.

Currently the schedule is:

1- Finish the tube buffered gainclone (1* Ecc88 gone)
2- Build the MOX crossover
3- Fit the P3A built long ago in a case
4- Build a tube preamp
5- Build a second TDA1541A dac with tube out.
I take the occasion to thank Pedja, Elso and Thorsten that made the 1st DAc (and also the second) possible.


Cheers

Andrea

 

[ThorstenL]

Re: Re: Re: Which preamp to choose for my ECC88s?

Konnichiwa,

where can I find this circuit?

http://www.fortunecity.com/rivendell/xentar/1179/projects/toccatamk1/toccatamk1.html

http://www.fortunecity.com/rivendell/xentar/1179/projects/toccata/Toccata.html

The original schematic used to float around the net but seems unavailable now. I'll e-mail it over to you if you mail me.

Sayonara

 

[fdegrove]

Hi,

I understand. What if I can get hold of 2*E82CC (how do they compare with the 5687=182CC ?) and 2* E83CC ?

E82CC tends to sound anemic to my ears. The E182CC and 5687 don't really compare but I'd much prefer the 5687 for preamp duties. E83CC (TESLA?) is fine for a MM phonostage.

And Yes, I'd gladly see your proposal for a (line) preamp with the parts I have.

The tube regulated 250V is highly recommended for this linestage.
It sounds neutral with the right passive components, I used tantalum resistors for anodes and bias resistors.
If you can't get them the Kiwames go well with the ECC88s.

Cheers,

 

[Andypairo]

Hi,

The tube regulated 250V is highly recommended for this linestage.
It sounds neutral with the right passive components, I used tantalum resistors for anodes and bias resistors.
If you can't get them the Kiwames go well with the ECC88s.

Cheers,

Hello Frank,
you mean to regulate the B+ or to "tube" regulate the B+?

Sorry for ignorance, but where to find tantalum resistors/Kiwames?

The 50k pot is placed at the input before the cap?

Cheers

Andrea

 

[fdegrove]

Hi,

you mean to regulate the B+ or to "tube" regulate the B+?

Whichever you prefer. I already have a 250VDC series reg. which I
've posted here:

PREAMP

Sorry for ignorance, but where to find tantalum resistors/Kiwames?

I haven't checked with Audiokit.it but these people in Holland have some values of both types:

KIWAME

The 50k pot is placed at the input before the cap?

That's indeed the idea.

Ciao,

 

[Andypairo]

Hi,

Whichever you prefer. I already have a 250VDC series reg. which I
've posted here:

PREAMP

Ciao,

Hello Frank,
I think I'll go for a SS type , since I want to make a preamp with the only tubes I have and it would be odd to buy some for a tube regulator (if I were to buy tubes I would buy something like the 5687... any chance someone has some spare ones and is willing to trade 'em with other components?... I have 3 Alps motorized pots... one might even go...)

Cheers

Andrea