ECC88 - upgrading from Teonex - Help ?

[clubsport911]

Hi there...newbie - really looking forward to this forum (only found it tonight by chance)

I'm somewhat confused about upgrading valves. I'm a power / automation / controls engineer by profession so the technicalities don't blind me, but I'm just not familiar with the ECC88.

I have some money to burn for new valves in my Musical Fidelity CD-T (CD Player) The current valves are Teonex ECC88.

I am looking at:-

1) Phillips PCC88
2) Phillips 6922 / E88CC
3) Brimar ECC88
4) Russian Military Grade E88CC (6H23N-EB)
5) Tesla E88CC (Gold)

or...

6) Something you might suggest !

In looking at them all, I see huge differences in the construction and finish, but frankly the CD player just uses them as a buffer.

Any advice. ?

Is the ££ expense worth it for a class A buffer ? Which ones would you recommend from my selection ?

What do you recommend from your experience and where would this fit in relation to the ones I have in mind ?

FYI - I am able to get these (I'm looking at them now in fact) from
£14 (Phillips) to £22/pair (Russian)

Many thanks for your help !

STEVE
UK

 

[SY]

The reality is that it probably doesn't make much difference in this application. But experimenting is cheap and easy. I haven't checked the data sheet, but from the number, I'd guess that PCC88 takes a different heater voltage so won't be a drop-in.

 

[planet10]

Any advice. ?

Some of the NOS ones get better reviews than the stock Russian tubes, but once they are cryo treated the combination of sonics & low microphony make them my choice -- that and that they are cheap... i got my last batch of 8 for $28 USD including postage (from Gintaras @ kwtubes in Lithuania). These often come labeled as 6922s as well.

dave

 

[clubsport911]

I'd guess that PCC88 takes a different heater voltage so won't be a drop-in.

I'd worked this one out late last night so I'd sort of eliminated that one myself

One thing I have noticed, is that the "getter" varies hugely

Flat - sold
Solid - domed
Ring - hollow

Any thoughts on what is "best" ?

I am looking for low noise, but i have devised a way to stop my valves ringing using grommets so the microphony is not so critical (+ the CD is remote from the speakers)

Rgds

 

[Yvesm]

I haven't checked the data sheet, but from the number, I'd guess that PCC88 takes a different heater voltage so won't be a drop-in.

Indeed, but I've done already and ... there are more differences between various brands that between some ECC / PCC 88.
Beleive or not, even E/PCC189 can be substitued for with success
Not always ! Perhaps, low level stages are more tolerents.
Try and listen, no risks exept a good surprise

Yves

 

[Shoog]

I'am using Miniwatt PCC88 in place of ECC88's. Absolutely no issues with them working. I expect longer life with running them at lower heaters. I find them the best I have tried in my preamp, balanced yet powerful bottom end.
Tried Mullard ECC88, found them much to soft sounding. Very old valve sounding.
Tried Sovteck 6922's good but brighter on the top end than the others.
Suprisingly I still have the old tubes from my MF X10D, which I guess might be the same as those used in the CD-T (always wanted one of those CD player from the first second I heard it, got the X10D as a compromise), they sound some of the most neutral ECC88's I have listened to, though not as good on the bass as the Miniwatt PCC88's. Might be worth sticking with them and sourcing replacements from MF.

To be honest they each have very subtle differences which will sink into the background in a day or two. Might not be worth the effort of doing anything unless you absolutely have to.

Just some thoughts.

Shoog

 

[SY]

It's a buffer. It's high level. Microphonics and noise will not be serious issues except for a defective tube.

 

[clubsport911]

(always wanted one of those CD player from the first second I heard it, got the X10D as a compromise),

Surely, all that distortion ? I love my CD-t to bits- it had some nice little tweeks that keep taking it higher and higher.

Anyhow thanks for all this advice...

I suppose, I ought to opt for the ones that have the best looking construction ? The Russian valves (6N23P) seem to have that in spades ! Much beefier.

Any other thoughts most welcome.

Steve

 

[paultb10]

MF CD-T valve replacement

Hi Steve, hope you're still out there!
Looking at your thread from a couple of years ago re replacement valves for the MF CD-T.
Mine has been faultless for 15 years until now and it sounds like it is playing through mud!!! Sort of a portable stereo that is running out of batteries!
It has been suggested that one of the valves has packed up, although both still glow. Anyway, I am looking to replace them and was wondering what the outcome of your thread was and which valves you went for.

Also, you mentioned some tweaks on the CD-T, improving the sound.....I am intrigued to know what they were!

Regards,
Paul

 

[p_ete2003]

I prefer soviet 6N1P EB in my SE amp's driver stage. On second comes (with this amp) Tesla's e88cc. Tesla is clear sounding and feels more natural than the 6n1p but 6n1p has more "grain" in sound and has more&deeper bass response. In fact I use the Tesla in my DAC..
The other brands I've dried are not in the same level with these two.
Only my opinion, no flames!!!

 

[EC8010]

I'm a power / automation / controls engineer by profession so the technicalities don't blind me, but I'm just not familiar with the ECC88.

If you're an electronics engineer then you'll get far better results by improving the circuit than by tweaking the flavour of individual components...

 

[richwalters]

ECC88's are RF tubes and is tempting to use them as preamp cathode followers. I did just that and had unexpected problems.
With sloppy decoupling and min screening they will nicely oscillate without notice around 450 Mhz and users will be quite unaware this is happening. Decoupling must be done with shortest leads directly from pins to nearest point on chassis.
As suggested, those inexperienced with sussing out RF in layouts are better off using the tamer 6N series.

richj

 

[Shoog]

The ECC88 has a bad rep for harshness. My experience has been that they are smooth and detailed. I would totally agree with everything Rich has said. The ECC88 tends to be one of the first tubes most novices try to use and usually with disappointing results. Great care is required in detailing a build and this is something that is difficult on early attempts.

Shoog

 

[clubsport911]

As part of the CD-T upgrade, I ended up with the Russian Military Grade E88CC (6H23N-EB). All worked well.

Improvements ? Hmm... after quite few moments and several CD's I detected some improvement in the low end. The CD-T is rather overblown @ the bottom end (perhaps a function of the crude 4X oversampling ) anyhow, it improved and the sound is leaner.

As far as improvments on the CD-T, they are many

Powersupply - added LC network to Transformer input
also added Improve decoupling capacitors to DC rail on the PSU.
Transformer - upgrade VA / improved Iq
All internal wiring (as far a practical) changed to higher grade silver screened cable (signal & power)
Power Supply Cable (to the CD) changed to Screened cable)
Mechanics - upgrade the mounting arrangement of the sub assembly
Power supply - all internal wiring replaced..

All minor tweeks but taken as a whole, ££ effective

Good luck !

 

[ionomolo]

Originally posted by richwalters
I did just that and had unexpected problems.
With sloppy decoupling and min screening they will nicely oscillate without notice around 450 Mhz and users will be quite unaware this is happening. Decoupling must be done with shortest leads directly from pins to nearest point on chassis.

At the local store they gave me 50 for 10€ and I was thinking in disposing them as in the first attempts i got terrible results (I was using them as mu-followers), but this schematic looks prety clean so i'll give it a try.

Standard "good" decoupling (bypassing B+ to ground using short traces with something like a 250V MKT) and 470/1000 uF will suffice?

How should these be screened?