So, I get my tube preamp today...

Pycroft

Hi all,

As per previous thread, I purchased a used Xiang Sheng preamp quite cheap. It also upgraded tubes...The owner said he put almost 400 dollars into this preamp. It will arrive today (Or so UPS says). The tubes will come seperate. This is my first tube gear, and I know literally nothing (Well, I read that 40 page primer on tubes, so I get what they are), but don't know the basics. Here are a few questions:
1 - Does it matter where I put what tubes? How will putting different tubes affect the sound?
2 - Is it plug and play? I read about a 'Tube Tester'. Do I need to test anything, or is it just screw them in and go?
3 - Is actually putting in the tubes difficult? I'm hoping it's just put in, twist, and go.
4 - The preamp has a button that says 'byp' which I'm assuming means bypass. The only kind of bypass I know of is to bypass a HT AVR so you can have a 2 channel and AVR setup together..I think it's called HT Bypass. Any info on what this button does?
5 - The pre has some buttons for treble and bass that my previous preamp did not have. Is it a safe bet to just keep them in the middle or can/should I play a bit?

Pics are included of the actual tubes...if you have any info on them, I'd love to hear it. Also, of the actual preamp to look at the buttons

Thanks for any info. If there is somethign I should know that I left out, don't hesitate to share. Nothing is too stupid, because I know nothing

James

Note...it won't let me attach the files because they are in another thread I'll link it: http://www.polkaudio.com/forums/showthread.php?t=95549&highlight=xiang+sheng

NJPOLKER

Everything matters.

thsmith

1 - Does it matter where I put what tubes? How will putting different tubes affect the sound?
The sockets the tubes plug into requires the right tube to be used. It matters. The manual will tell you or the socket will be labeled
2 - Is it plug and play? I read about a 'Tube Tester'. Do I need to test anything, or is it just screw them in and go? Not required but your pre probably uses aty least 2 of the same type tubes which should be matched. I have a secore TC142 which is good for determining shorts and the tube is good or bad. I would wait and see if you plan to stay with tubes before thinking about a tester. You may be able borrow one of take your tubes to a shop and for a small fee have them test ed for you.
3 - Is actually putting in the tubes difficult? I'm hoping it's just put in, twist, and go.
No twisting. The 7 and 9 pin small tubes have a gap in one part just line the gap wit hthe socket. Bigger tubes have a key that aligns with the socket.
4 - The preamp has a button that says 'byp' which I'm assuming means bypass. The only kind of bypass I know of is to bypass a HT AVR so you can have a 2 channel and AVR setup together..I think it's called HT Bypass. Any info on what this button does?
Run your L & R AVR output to Pre bypass input. when you select bypas the pre just passes the AVR signal straight threw to your amp. When not in bypass the AVR is out of the Pre's circuit for 2 channel listening.
5 - The pre has some buttons for treble and bass that my previous preamp did not have. Is it a safe bet to just keep them in the middle or can/should I play a bit?
yes but you find you might use them based upon your preference. None of my Pre's have had tone controls and never missed them.

heiney9

I don't understand the question about putting the tubes "anywhere". They need to go in their appropriate spots. Some of the larger tubes may have a center pin with a "key" (notch) to orientate them. There is no twisting just line the pins up with the socket and gently push. Avoid any side to side movement, especially when removing them. Use gloves or a sock when handling the tubes.

Any older tubes (larger) using a micanol base (brown, black or red). Always grab by the base when removing, as the glue that seats the glass to the base can get old and if you pull on the glass sometimes you can damage the seal. Newer issue tubes with micanol bases won't have the glue issue since they are new, but it's a great habit to get into, always pulling on the base rather than the glass. For small signal tubes it's not an issue.

If you didn;t get any instructions then consult with the prior owner about where the tubes go if the chassis isn't marked.

If you put a signal tube where a rectifier goes or visa-versa you will surely have a nice light show

heiney9

I believe your pre-amp takes 12AX7's, 12AT7's and some sort of smaller rectifier tube(s). Open her up, and on most Chinese gear I've seen the sockets are clearly marked somewhere on the pcb or chassis. The tubes should be marked as well. They need to go in the appropriate spots.

Pycroft

Thanks for the info so far. I know some were dumb questions. Some follow up...if I'm using this in a strict 2 channel setup, the bypass button does absolutely nothing...correct? Also, no twisting, good to know I guess I just gently press them into place by the base of the tube?

I'm sure I'll have more questions when I see the actual tubes and amp. I may actually post a picture of the preamp with the tubes in before setup to make sure I didn't screw anything up. Any further advice, keep it coming, and thanks.

James

heiney9

For your particular unit, I have no idea what the bypass does. It's either to bypass some controls (like tone, etc) or it's for HT use. You won't do any damage by engaging or disengaging that control.

heiney9

Don't be afraid of tubes!!!! They are not as fragile as you think.