HIWATT SA212

[jujub]

Hi,

this is my first post here, and I'll speek of my first HIWATT amps : an SA212 50W

I bought it from the origibnal owner who bought it in 1975. he didn't change anything to it from the first day ( and no service also), and the amp was in room for 10 years without been used at all.

When i took it, it was quite dirty ( as you can see above) but it is 100% original down to mullards tubes! S/N is 7151.





I already clean the tolex and the panel it with a slightly humid cloth and the inside cabinet with vacuum cleaner with brush at low speed.

Here are some question :

How can I clean the grill cloth?

Should Ihave it recap? I think so but not sure.

Should it use It for some reahrsals at reasonnable level without a recap?

Is it really all purpose as it seems to be?Can I use it with bass? Keyboard?


Thanks.

[jujub]

photos:



Speakers :


back panel :


back

[hohohiwatter]

yes u can use it for keyboards and bass, but be a bit careful as the speakers are old and may not like the bottom end, but they may well take it no problems.
you can always use the speaker out and put it into a speaker cab.

the grill cloth looks in good condition, i wouldnt bother cleaning it looks nice as is.

have a play through it at rehearsals and see what u think!

[OldSchoolDave]

the grill cloth looks in good condition, i wouldnt bother cleaning it looks nice as is.

I agree. It has character now. Attempting to clean it could destroy the "cloth" (it's really a paper product).

If you are up to the task, try removing the chassis and top board to take some pictures of the inner circuitry. A visual inspection (as is well documented elsewhere on this board) is the best indicator regarding filter cap condition.

Unfortunately, the original design requires de-soldering the speaker leads before the chassis can be removed. On my SA212, I wired a speaker jack into one of the unused power tube sockets to facilitate chassis removal (also posted elsewhere on this site).

Nice amp!

Dave

[Dr.HI-TONE]

yes, what Dave said!

[jujub]

thanks for your answer,

Ok I'll let the grill cloth as it.
I'll also make some inspection the chassis and top board and take some pictures of the inner circuitry as you asked.
I've just played it my a new band we made yersterday. Amazing
Great definition, clarity and punch! We played some Jethro tull - Zeppelin & who songs, ans I couldn't ask for a better tone. I couldn't beleve how great It works with effect.I play it with my echoplex, and a fuzz and really enjoyed it.
And have some more question for you, if you want to answer :
What the purpose of polarity switch?
How can I use the external speaker jack?

Thanks a lot!

[OldSchoolDave]

What the purpose of polarity switch?

Polarity switches were added to U.S. amps before grounded (3 wire) circuits came into existence. The switch would reverse the two legs of the alternating current. One position would generally have less hum than the other (depended on which way the non-polarized plug was inserted). In retrospect, it was a bad and, sometimes, lethal "solution".

Vintage amps should be re-wired with properly grounded/earthed connections and the Polarity switch should be bypassed.

How can I use the external speaker jack?

Because the internal speakers are wired directly to the output transformer's 8 ohm taps, the external jack (wired to the 16 ohm taps) will disconnect the internal speakers when engaged. On a combo, you can use one or the other - not both.

Dave

[bikehomero]

The Amp looks really good! Just as the grillcloth dosn't look bad. I've just bought a 4x12 cab for restauration. It has bad looking grillcloth but i had a nice result using dry soap for carpets. You can find fotos in the actual cabinet thread. I don't think you have to clean yours as it looks much better than mine.

I've been at my amptech with my Custom 50 as well 2 weeks ago. There had been visible the one or other bubble at the caps. He checked them all and told me: the one who likes to replace anything should be cutted the fingers. "Dave allways uses only the best". Tubes are all between 85 and 105%, supermached EL 34 as well. He is the no.1 tech for Echolette and Dynacord and had been well known with Dave Reeves, so i trust him and let everything as it is. He could tell me as well, it should be necessary to change the tubes and take away my Mullards and i think there are techs out there doing like this. So hopefully you have a trustwothy tech you can go to do the first check.