Direct wiring instead of a driver board?

[parabellum]

Ok I got some more questions. Not sure if I should start opening up new threads for each one of them?

1. Tube selection

I am leaning towards getting these tubes:

V1 - Ei 12AX7E $17.95 at http://thetubestore.com/12ax7.html
V2-V3 - JJ ECC82 replacement for 12AU7 $9.95 each at http://thetubestore.com/teslaecc82.html
V4-V7 - JJ EL34 $27.35 matched pair at http://thetubestore.com/teslael34l.html


Yey or nay?
Comments?

2. Preamp

What preamp should I build for this ST70 clone? I did a search on the board for some good schematics for a preamp that goes well with the st70 but didnt find anything concrete. I ran across a reference to a few preamps but couldnt find detailed schematics except for this one

http://www.decware.com/linestage/zp1.htm

http://www.audiocircle.com/circles/viewtopic.php?t=7661


3. Transformers

@mesherm You mentioned the edcor trannies as a cheaper alternative that works well. How difficult is it to adapt them to go in a place of a hammond or a dynaclone and is there any documentation on how I would do that?


4. Speakers

Might as well start thinking about speakers that go well with this setup. I haven't done too much research in this area. Originaly I thought about building them too but instead I probably wanna get some used ones or something if its affordable. Though about getting the dynaco speakers off craiglist if I can find them.

[mesherm]

For JJ tubes try here:
https://ssl.eurotubes.com/cart/index.ph ... egory_id=3

A nice upgrade is the JJ KT-77s. I run a pair in triode mode and they sound sweet. As to small signal double triodes, I refuse to use any new ones after a couple bad experiences with them. I use NOS (except in the seldom used phono sections of my two PAS 3xs where I use Sovtek 12AX7WAs just to take up space.

Preamps: well as I said I have two PAS3xs that I am happy with so I haven't tried other tube type preamps.

I used a set of Edcors on an old ST70 chassis so I just drilled new holes.
I mounted a set of Hammonds on a new ST70 chassis but refused to drill into a new chassis, rather I fabricated some adapter plates out of 3/16" aluminum plates. The wiring is straight forward. It seems no matter what I do and even though I have a 50-50 chance of getting the feedback polarity right, every amp has to have the tranny leads swapped. I have learned to leave the leads uncut and just tack them in place until a preliminary powerup with AC voltmeter across a speaker load resistor and a finger on the off switch. :o

[parabellum]

KT77s can be droped in place of EL34s with no modifications right? I'll spring for those if you say they are a good upgrade.

I want to build my preamp too so I guess the PAS3x is out.

And since I'll be building my own chassis drilling holes for the edcors is not a big deal. I just I guess need to compare manuals to see what goes where :S

Yellow_Light_Colorz_PDT_16 lol at the finger on the switch method Yellow_Light_Colorz_PDT_06

[kheper]

JJ ECC82 tubes sound a little harsh
to my ears. NOS Tung-sol 12au7s
sound great and can be had for
a bit less than an arm and a leg.

The JJ EL-34s are the best in
price/performance among new production
EL-34 tubes - period -.

I use solid-state, Adcom preamps. They are
transparently sounding, and the once
expensive models, the GFP565 and
GFP555II, have lab-grade direct outs. The
Adcom preamp/tuners go for a song on
e-bay. Look for the GTP 350, 400 or 450.
Sometimes they go for $100. The preamp
circuitry is excellent; The tuner is so-so.

I am building an st70 clone with Transcender
transformers, perhaps with 807 tubes. They
produce many different models. Mine are
30W continuous, 5K center tap, 40% UL
taps, etc. They go for $90 on e-bay. I
cannot testify to their quality, since the amp
is not yet built.

Klipsch Heresy speakers do what good
speakers are supposed to do. They
are very sensitive and pump out a
heavy bass.

[mesherm]

I agree about the sound of the JJ ECC82s. Pick up some JAN 5814A tubes, they are basically the same as 12AU7s. Even 12BH7As would work if you have enough extra filament current. If you can't find any 5814As I might be able to come up with some from my secret stash.
I like the sound of EH 6CA7 fat bottles also and they will drop right in.

[parabellum]

Ok so Tung-sol 12au7 arent too expensive on ebay so I'll get those then with KT 77 instead of EL34s if they are a direct swap. Can the Tung-sol 12au7 be directly swapped with ecc82 ?


I guess if I can get an adcom preamp for as little as 100 then I'll just pick one up but I'd still rather build my own matching pre-amp to go with the amp so if anyone has any suggestions I still want to hear them.

Klipsch Heresy's go for about 400 bucks on ebay and craigslist ....

Yellow_Light_Colorz_PDT_13 this little project of mine is getting progressively more expensive Yellow_Light_Colorz_PDT_14

[parabellum]

I agree about the sound of the JJ ECC82s. Pick up some JAN 5814A tubes, they are basically the same as 12AU7s. Even 12BH7As would work if you have enough extra filament current. If you can't find any 5814As I might be able to come up with some from my secret stash.
I like the sound of EH 6CA7 fat bottles also and they will drop right in.

Thanks. There seems to be a few of 5814As on ebay so I'll try scoring some when my part list is complete ... are they better then then tung-sol?

Is EH 6CA7 better option then both el34 and kt77?

[sorenj07]

I've used some of the better quality pots with the locking shafts for bias, what type of 10 turn are you using ?

this type:

http://www.etisystems.com/mw22.asp

available at Mouser, search Potentiometers & Rheostats, then "Precision Potentiometers & Dials". manufacturer is ETI, and these are the $9 ones. they have a very cool small toothed sound when they turn, very precise sounding.

[mesherm]

Its a personal thing for me. I just don't like the look of the rounded tops on JJs and some I've bought were as straight as a famous tower in Pisa. Go for the best deal $$ wise. Electro Harmonix and JJ are well respected for their EL34s so you can't really go wrong. Buy from a place you trust to do proper matching though, places like Antique, Triode or Eurotubes as an example.

[parabellum]

OK I'll try to pick up some KT77s or EH 6CA7s depending on availability.

So probably best to stay away from ebay when matched pairs are required?

[kheper]

I guess if I can get an adcom preamp
for as little as 100 then I'll just pick one up

Only the adcom preamp/tuners can be
gotten so cheaply.

Is EH 6CA7 better option then both el34 and kt77?

The 6CA7 is an el34. The Electro Harmonics
tube was designed to be an exact copy
of the Phillips 6CA7.

[parabellum]

I guess if I can get an adcom preamp
for as little as 100 then I'll just pick one up

Only the adcom preamp/tuners can be
gotten so cheaply.

Is EH 6CA7 better option then both el34 and kt77?

The 6CA7 is an el34. The Electro Harmonics
tube was designed to be an exact copy
of the Phillips 6CA7.

Yeah i saw the 555s for much more.


BTW I can't thank you guys enough for all your help and patiance to answer my noobish questions. Its like learning a new language for me so I got google open non stop reading up on the stuff.

PS I did absolutely zero work today. I spent the whole day doing research :)

[wiredbecker]

BTW I can't thank you guys enough for all your help and patiance to answer my noobish questions. Its like learning a new language for me so I got google open non stop reading up on the stuff.

PS I did absolutely zero work today. I spent the whole day doing research :)

Allow me to echo that sentiment. I've been doing the same thing since I registered a few weeks back. Thanks tons guys.

[Slartibartfast]

2. Preamp

What preamp should I build for this ST70 clone? I did a search on the board for some good schematics for a preamp that goes well with the st70 but didnt find anything concrete. I ran across a reference to a few preamps but couldnt find detailed schematics except for this one

http://www.decware.com/linestage/zp1.htm

I completed the Decware ZSP-1 a couple of weeks ago. This is a nice sounding preamp that was fun to build. I used 6922 tubes in mine. His plans used 6n1p but, they are all a part of the 6dj8 family.

[parabellum]

2. Preamp

What preamp should I build for this ST70 clone? I did a search on the board for some good schematics for a preamp that goes well with the st70 but didnt find anything concrete. I ran across a reference to a few preamps but couldnt find detailed schematics except for this one

http://www.decware.com/linestage/zp1.htm

I completed the Decware ZSP-1 a couple of weeks ago. This is a nice sounding preamp that was fun to build. I used 6922 tubes in mine. His plans used 6n1p but, they are all a part of the 6dj8 family.

Did you run across any problems with the schematic? What transformer did you use?