Scott 222C

[thefragger]

I just bought this and its on its way!



It needs work, to say the least! I'm pretty excited!! I just have to sell a couple pieces before this one comes home and I'm golden, to keep the audio equilibrium happy in my house.


I'd like to start researching what needs to be done to this amp. Does anyone here have any good H.H. Scott resources that they'd like to share?

 

[kpaxfaq]

Seems like Scotts have been getting a lot of love in the tube section lately. Looks like that will clean up nice :thmbsp:

 

[Tinkerbelle]

Big congrats; that's a really nice integrated. :thmbsp:

For some info, try here:
http://www.hhscott.com/pdf/fs/222C-C1.JPG
http://www.hhscott.com/pdf/222C_LK48B.pdf
http://www.hhscott.com/integrated_amps_stereo.htm

 

[kymers]

I've got the same one on deck for rehab, near mint except for one big scratch on the faceplate.:sigh:, all orig tele's including the op tubes!

Dunno if the sherwood 5000 will be first though

scott

 

[shelby1420]

Should clean up nice!! I have the LK 48 ( KIT OF THE 222C) coming, fellow says its factory wired, we'll see!!

 

[kansei]

I have one on the bench right now. Watch out for noisy 7199 tubes, they always throw me for a loop. I rewired my last project amp from 7199s to ECF80 tubes and found some nice ECF80 Bugle Boys.

 

[thefragger]

I was thinking of modding it to run EL84 and putting in some 6P14P-EV tubes. I haven't heard of the ECF80 tubes before tonight, but I've got my studies to tend to!

 

[kpaxfaq]

I was thinking of modding it to run EL84 and putting in some 6P14P-EV tubes. I haven't heard of the ECF80 tubes before tonight, but I've got my studies to tend to!

I thought those Russian tubes are direct replacements for 7189 too because they can handle the higher plate voltage...Someone please correct me if I'm wrong

 

[kansei]

I was thinking of modding it to run EL84 and putting in some 6P14P-EV tubes. I haven't heard of the ECF80 tubes before tonight, but I've got my studies to tend to!

ECF80 is the same part as 6BL8. I read a bunch about this during my last project and found out that a lot of 6u8 tubes (another cousin to ECF80) are noisy. I must have a bucket-full of 6u8 or other equivalents, tried them all and ended up buying Bugle Boy ECF80.

 

[bricktop]

I was thinking of modding it to run EL84 and putting in some 6P14P-EV tubes. I haven't heard of the ECF80 tubes before tonight, but I've got my studies to tend to!

A big recommendation here for the 6P14P-EV. The 222C runs 7189s and a rather large B+, probably too much for most EL84s (I've tried NOS GE EL84s and they redplate, although not all EL84s may do this). With 6P14P-EVs in, there are no problems :thmbsp:

 

[Glassweights]

This thread

Here is a good thread on rebuilding them.

http://www.audiokarma.org/forums/showthread.php?t=198051

The argument near the end is kinda interesting too. Unfortunately it is about a completely different tube that is not used in this amp!

There are a lot of good tips thrown out about how to rebuild them.

Good luck!

Dan

 

[thefragger]

A big recommendation here for the 6P14P-EV. The 222C runs 7189s and a rather large B+, probably too much for most EL84s (I've tried NOS GE EL84s and they redplate, although not all EL84s may do this). With 6P14P-EVs in, there are no problems :thmbsp:

Interesting... I might have to get myself a set. I read somewhere that as-is the power transformer is pushed near it's limits; would it be bad to run the power to the tubes a little under-spec?

Here is a good thread on rebuilding them.

http://www.audiokarma.org/forums/showthread.php?t=198051

The argument near the end is kinda interesting too. Unfortunately it is about a completely different tube that is not used in this amp!

There are a lot of good tips thrown out about how to rebuild them.

Good luck!

Dan

Excellent! Thanks for the link and the luck!!

 

[soundguy]

I thought those Russian tubes are direct replacements for 7189 too because they can handle the higher plate voltage...Someone please correct me if I'm wrong

they are direct drop ins. new el84's wont work in there, or at least none have that I have plugged into a scott or fisher. Old el84's on the other hand work just fine and seem to handle the voltage just fine.

 

[thefragger]

Wait a sec; Bricktop, maybe you can clarify... the 222C I'm getting is wired for 6U8 (ECF80) tubes? :scratch2:

 

[bricktop]

Wait a sec; Bricktop, maybe you can clarify... the 222C I'm getting is wired for 6U8 (ECF80) tubes? :scratch2:

Yup. :yes: The 7199/6U8s/6GH8s are the driver tubes. Some scotts had 7199s, some had 6U8s. They work similarly, and I'd rather have one wired for 6U8s as they are way cheaper. The 6GH8 will also work in a socket wired for 6U8s, and is also cheap. No-one makes 7199s anymore and they are scarce, and frankly I think they sound the same as 6GH8s.

The EL84s/7189s/6BQ5s are the power tubes, and are pin compatible, but have different ratings. I run 6P14P-EVs (7189s) and they idle stably at about 12mA each iirc. There is no direct bias control on the Scott, only a balance potentiometer, but I've had no issues with the power transformer.

 

[thefragger]

Yup. :yes: The 7199/6U8s/6GH8s are the driver tubes. Some scotts had 7199s, some had 6U8s. They work similarly, and I'd rather have one wired for 6U8s as they are way cheaper. The 6GH8 will also work in a socket wired for 6U8s, and is also cheap. No-one makes 7199s anymore and they are scarce, and frankly I think they sound the same as 6GH8s.

The EL84s/7189s/6BQ5s are the power tubes, and are pin compatible, but have different ratings. I run 6P14P-EVs (7189s) and they idle stably at about 12mA each iirc. There is no direct bias control on the Scott, only a balance potentiometer, but I've had no issues with the power transformer.

Rock on, now I understand! Thanks so much for breaking all that down for me!! :thmbsp:

Quick edit; do I want to install four bias pots (one per power tube)?

 

[Blast]

Did you get it yet, fragger? You'll find a wealth of knowledge on AK. Have you been to hhscott.com? Plenty of people to help you along the way. You made a wise investment.

Here is my 222C that I rebuilt in '07. New plate & power supply resistors, bias voltage bridge rectifier, multi-stage caps on top and orange drops on the bottom:



I should do a little better job of trimming/insulating the leads on the bridge.

I got a 2nd 222C in '08 that I'm in the process of working on. It needed a new power transformer and with the bad economy it's taking a little longer.

It's your amp but 4 bias pots to me is overkill. Using the correct values for the bias voltage resistors will get you close enough.

Post photos as you go. We'd love to see the progress you make on it.

 

[thefragger]

Wow Blast, your amp looks awesome underneath! I should have mine by Monday.

Aside from the links that Tinkerbelle posted earlier I haven't looked around that site much-- I'll be sure to join up there when I really get stumped, though!

I suggested the four bias pots as an alternative to having a matched quad of tubes, so that I could balance them out myself. (unless I'm completely wrong in my understanding how bias pots work, I still have some reading to do!)

I've got some MUR860 (8A, 600V ultrafast rectifiers from ONSemi) kicking around here that I could build a bridge out of, maybe overkill? I was thinking all-new metal film resistors as well. Advantages/disadvantages of metal film vs. carbon comp?

 

[Blast]

Thanks, fragger!

Is yours coming with tubes (it certainly doesn't look like it from the photo)? If not, it's not too difficult to order up 4 matched tubes. I normally use EL84M, myself. But, I think I'd like to try a quad of Russian tubes and see how they work in the 222C I'm still working on.

I suppose you could make an argument for the benefits of fine adjustment from 4 bias pots of you had 4 mixed high quality, old stock output tubes laying around that you just couldn't bear not to use in her... But, myself, I would rather not butcher the chassis unless I was positive there would really be a sonic difference.

Your diodes would work fine. But so would an inexpensive bridge rectifier and it would be a lot easier to install. It's just a bias supply.

How are you going to be able to sleep until Monday???

 

[Patrice B]

The 6GH8 will also work in a socket wired for 6U8s, and is also cheap.

I assume the reverse is also true as I ran 6U8's for almost a year in my LK-72A. The sockets are labeled 6GH8.