What will my 1000a sound like?

[Old Guy8]

I bought it from original owner. He bought it in Okinawa while in the Navy in 1966. Has not been used in 25 years. May be some original tubes. The only tubeish amp I have is a Rogue Sphinx hybridwith two 12au7 Mullards in the pre and a class D power section. I have not heard tube amp since my folks Admiral AM, longwave, 45/78 auto phono. Also have Sansui G4700, Marantz 2245, Pioneer SA7500 ii. How will this sound in comparison after a rebuild? I'm not at point to commit to start of rebuild, yet. Other projects first. Just like to know how it will differ.
thanks
Old Guy8

 

[markn2wae]

Describing the sound of equipment in text is almost an impossibility, making comparisons difficult.
The Sansui 1000A is worth restoring and using, when I tried most solid state equipment the sound was OK, nothing to write home about.
But... after three months of replacing bad capacitors, a gassy tube, some resistors (I worked on it "on and off", not three months straight!) the sound was like "hey, I never heard my music sound so good, lets try another record..."
Any "listener fatigue" I may have experienced in the past was gone! (what I mean by that is, in the past, using SS equipment, if I put on some music, my mind was always being "distracted" by other thoughts and not really enjoying the sound, there was nothing specific, just subconsciously not enjoying it as much as I should be).

Yes, the 1000A will be an "ear pleaser" when properly restored, HOWEVER.... as they say "you can't get there from here", meaning, NEVER power up the set without getting the bad "time bomb" bad parts replaced first! (these bad PIO, Paper In Oil caps. will be bad because of age and WILL FAIL).

You need to replace the bad capacitors, possible bad tubes and resistors, and adopt a good ventilation strategy (PM me if you want) if you want a strong usefully life from this set, once restored, it will please you with its unique sound.

Mark T.

 

[Old Guy8]

Describing the sound of equipment in text is almost an impossibility, making comparisons difficult.
The Sansui 1000A is worth restoring and using, when I tried most solid state equipment the sound was OK, nothing to write home about.
But... after three months of replacing bad capacitors, a gassy tube, some resistors (I worked on it "on and off", not three months straight!) the sound was like "hey, I never heard my music sound so good, lets try another record..."
Any "listener fatigue" I may have experienced in the past was gone! (what I mean by that is, in the past, using SS equipment, if I put on some music, my mind was always being "distracted" by other thoughts and not really enjoying the sound, there was nothing specific, just subconsciously not enjoying it as much as I should be).

Yes, the 1000A will be an "ear pleaser" when properly restored, HOWEVER.... as they say "you can't get there from here", meaning, NEVER power up the set without getting the bad "time bomb" bad parts replaced first! (these bad PIO, Paper In Oil caps. will be bad because of age and WILL FAIL).

You need to replace the bad capacitors, possible bad tubes and resistors, and adopt a good ventilation strategy (PM me if you want) if you want a strong usefully life from this set, once restored, it will please you with its unique sound.

Mark T.

Mark,
Thanks for response. Before I picked it up, I got the do not power up warning from AKers. I bought it unheard and will remain so til rebuild. Describing sound is difficult. I have read a yhread where you mentioned adding cooling fans. I will contact you prior to work.

 

[Shadowdog]

I recently posted this for someone wanting repair another brand of tube amp:

Best not to plug it in without using a variac to slowly bring the voltage up over several hours while monitoring the current draw or Amperage which can happen if old cap (s) in the PS or Coupling ones short out.

Always run a tube amp with old speakers (or 25W 16 ohm resistors ) hooked up or you risk the output transformers and never short cycle one. Wait till the tubes fully cool before switching on again.

You will end up replacing the mentioned caps for best reliability (all transformers are at risk and output tubes) and usually sonics
will benefit. Resistors can be checked in circuit with the tubes out as they usually go high.

Tube sockets and pins can be cleaned. Pots and switches may need cleaning & a proper lube.

If diy take lots of detailed pics and maybe only replace one cap at a time so to not mix up connections.

 

[Old Guy8]

Shadowdog,
Thanks for response. I may do my first amp rebuilt on something less densely packed and of less interest to me.
I took a high school electronics class in1968, but not much stuck. My background was tool designer in a factory.
There is a restoration shop here in Rockford that I know specializes in SS amp and receiver restorations. Eventually may ask them about this. I think they do tube work also.

 

[Old Guy8]

One more question. If in this area a Marantz 2245 restoration at a shop cost $350 to $400, would ballpark about $500 be expected to restore this?

 

[larryderouin]

Pretty much. Every paper in oil capacitor inside is a time bomb LITERALLY! All of the electrolytic caps must be replaced along with the Voltage doubler caps. These are woefully underpowered. 200uf @ 300V each is not enough. Bump them up to 470uf @ 450V. And take a good close look at the two power resistors sitting next to the Power transformer. If they how any cracking other than the surface glaze, replace them. Mark know's the exact wattage and voltage for each one. I just replaced them with aluminum surface mount types and mounted them on the barrier panel between the power transformer and the front of the unit AND the Dial asembly cover.

Noticed that your's is a newer version with the big resistor in the middle of the chassis. Make sure that is intact and tests ok too.

Test the 7591's BEFORE you power up. Real good possibility they are shot. Sansui designed it to run hard, and the output tubes took a beating. But with the right updates, parts and adjusting them for between 70% and 80% of max plate dissipation, you'll be able to run any 7591 out there and not have to worry about them. I would highly recommend the NEW Tung-SOL 7591 Re-Issues over the EH7591's mainly as they have the smaller original sized glass envelope. The EH's will work, but it gets awful hot, with little room for ventilation.

I run mine without a cover and no fan. DO NOT RUN COVERED without a cooling fan. This unit runs very hot!! It'll literally cook eggs on the top. Mine has been uncovered since 2009 and have over 2000 hours on the EH's. They still test @ over 95% of new. Also the 6AN8's and the 6BQ8's are run very hard and put away wet. These are your driver / phase inverter tubes (6an8) and FM Osc/Mixer, FM Muting, and 1st stage in the MPX. Suggest new tubes for the 6AN8's if weak, and also the 6BQ8's. If you are on a budget, the 6DT8 is a direct sub for the 6AQ8 and costs about 1/3 of the 6BQ8. My 1000A doesn't like a 6DT8 in the MPX but otherwise it's fine with them.