Xiangsheng 708b vs LD2+ ?

[Guest Trappist]

' date='13 Sep 2006, 04:40 PM' post='78522']

Sounds to me like it's a transformer problem... does changing the power cable help?

 

No it doesn't help. I also tried pluging it into another power outlet and doesn't make any changes.

 

Maybe it's the same problem as edwin's

http://www.sgheadphones.net/index.php?showtopic=5443&st=60#

 

I saw edwin's problem and I tried playing around with the interconnects but it doesn't change really.

 

Check the interconnects if it's securely plug in. Usually it's the IC.

 

I think they are securely pluged in. It could explain the noise before switching on the power amp?

[zer061zer0 0]

Yup agree on getting a DAP. I'm currently using a CD63 mkII also. Will be doing the mods on it

Maybe a DAC and a pair of speakers later

 

 

Whats a DAP...?

 

I am actually using my cd63se for my living room for the speakers. Sometimes i will bring my XS to the living room as a preamp.

 

Heaphones are usually use in my rm, thus am unsure if i should get another cdp..

 

I read abt pcdp, how is it compared to a cdp.

 

Zhapchit,

what mod are u planning to do ..?

[zhapchit 0]

Whats a DAP...?

 

I am actually using my cd63se for my living room for the speakers. Sometimes i will bring my XS to the living room as a preamp.

 

Heaphones are usually use in my rm, thus am unsure if i should get another cdp..

 

I read abt pcdp, how is it compared to a cdp.

 

Zhapchit,

what mod are u planning to do ..?

 

 

Digital audio player i believe

 

Mods to do.. changing opamps.. caps.. etc.. If you want to discuss that guess we'll need to start another thread for that.

 

[zhapchit 0]

Anyone intesterested in getting 6Z4 spares? I'm wondering how long will the 6z4 last

[viix 0]

No it doesn't help. I also tried pluging it into another power outlet and doesn't make any changes.

I saw edwin's problem and I tried playing around with the interconnects but it doesn't change really.

I think they are securely pluged in. It could explain the noise before switching on the power amp?

 

You can try connecting the IC to the power amp and leave the XS end unconnected. Is there still noise? Maybe it the circuit of the poweramp. Anyway, the proper way of powering up the devices is from source first down the chain to the power amp. Not too sure why, but I was thought to operate it that way.

[Mackie 0]

You are experiencing a typical case of impedance mismatch, thus, succumbing to capacitance of the interconnects and rolloff in freq response. Not all pre-amp and power amp can work together. Please read paragraph 4 in the enclosed link.

 

http://www.vtl.com/pages/system_match.html

 

You are right about one thing though, its a electrical problem. By rule of thumb, the ratio of output impedance of pre-amp to input impedance of power amp must be greater than 1:10. Tube amps have higher input/output impedance than solid state. The situation is further worsened if you are matching a tube pre-amp to a solid state power amp.

 

http://www.hometheatermag.com/readerqalp/

Edited September 14, 2006 by Mackie

[Guest Trappist]

You can try connecting the IC to the power amp and leave the XS end unconnected. Is there still noise? Maybe it the circuit of the poweramp. Anyway, the proper way of powering up the devices is from source first down the chain to the power amp. Not too sure why, but I was thought to operate it that way.

 

Thanks, I already did that just not to ear the noise

 

You are experiencing a typical case of impedance mismatch, thus, succumbing to capacitance of the interconnects and rolloff in freq response. Not all pre-amp and power amp can work together. Please read paragraph 4 in the enclosed link.

 

http://www.vtl.com/pages/system_match.html

 

You are right about one thing though, its a electrical problem. By rule of thumb, the ratio of output impedance of pre-amp to input impedance of power amp must be greater than 1:10. Tube amps have higher input/output impedance than solid state. The situation is further worsened if you are matching a tube pre-amp to a solid state power amp.

 

http://www.hometheatermag.com/readerqalp/

 

Thank you for your inputs.

 

I guess I am doomed then. Or I have to change my power amp. It is planned but only in a few months.

 

What are your thoughts on the loud noise before I switch on the preamp? Just curious because I just switch on the power amp after the preamp.

[edwinywh 0]

Hi Edwin,

 

I managed to find some cheap rca to mini cables to hook up my ibook to the XS and listening thru my Ad500 heaphones.

 

The results was not gd, the same track that i used to listen to all my systems, perform really badly, i believe that a cd player would reap remakrable improvement.

 

I also spent some time hooking up the XS to my philip dvdp (mackie is really against this though),

hook up to a old vcd player, which i believe holds a linear power supply, lastly my marantz cd 63 se.

 

cd 63 gave the best results lotsa of details, in fact i am hearing more stuff that i never realise before. my old vcd player is the next best though there is some lost to some background music. dvdp perform the 2nd worse a little blurry though.

 

The ibook was the worst, it seems like the singer is singing behind the instruments and competing with the music. U try playing a cd thru ur ibook and see if what i discover was true.

 

Do let me know ur findings.

 

Regards.

 

Hi!

 

Well,I do connet my IMAC to my headphone before. Basically I seldom listen straight from the cd in the mac becos I feel that its very much louder than i listen in mp3 formats.Thus,I hear more noise and I dun really like it.I normally reipped it into my itunes to be transfered into my ipod. =)

 

However,back to wat u are saying.... For me,I dun experience the singer being behind the instruments competing with the music etc. The differences between my mac and my xbox cd player are the extra details of the instruments and the whole song,and the enlarged soundstage.Lastly,the volume is higher from the xbox cd player than my mac too. =)

 

[Mackie 0]

 

Thank you for your inputs.

 

I guess I am doomed then. Or I have to change my power amp. It is planned but only in a few months.

 

What are your thoughts on the loud noise before I switch on the preamp? Just curious because I just switch on the power amp after the preamp.

 

 

You should switch on your equipment in the same fashion as signal flow ie. in the order of source > pre-amp > power amp. In addition, try to give about 10 secs before switching on the subsequent equipment, in order to allow the preceding equipment to stabilize (upon powering up). It's more imperative to adopt this habit with your pre-amp/power amp. Reverse the order (without a need for pauses as advised on power up) from power amp > pre-amp > source, when powering down.

 

Because your power amp is already active, the power surge in source or pre-amp is thus fed to the power amp and thence to speakers, resulting in a thump. This is not good for your system in the long run. But if you have followed this procedure and still hear a thump whenever the power amp is switched on, it merely confirms the amp doesn't have protection relays in output or input or both paths. Some designers do not adopt this approach for the sake of better sound quality. If the thump is none too loud, don't worry about it.

 

Just in case you are not aware, never never never switch interconnects from any equipment when it's switched on. The spikes from removal and insertion of the cables can cause sensitive electronic components to fail.

Edited September 15, 2006 by Mackie

[Tristram 0]

Hi, I just saw in Ebay that the XiangSheng 708B Pre Amp going for current bid of below 40 SGD for a few hours more. Is it worth getting it at that selling price? And is it the same XiangSheng this thread talking about that a fellow forummer recommended me. I was considering between LD2+ and this XS708b since this thread compared... Just want to make sure. Thanks.

Edited September 15, 2006 by Tristram

[edwinywh 0]

Hi, I just saw in Ebay that the XiangSheng 708B Pre Amp going for current bid of below 40 SGD for a few hours more. Is it worth getting it at that selling price? And is it the same XiangSheng this thread talking about that a fellow forummer recommended me. I was considering between LD2+ and this XS708b since this thread compared... Just want to make sure. Thanks.

 

 

WAH! serious? so cheap? most of us i think bought at much higher price than this. Well,I did. And I like this amp alot. Lots of potential. Lots of mods to play around. Great amp. Check with the seller more about the amp before biding. =)

 

BUy buy buy! Join us,the 708B gang. Hahaha...

[Tristram 0]

WAH! serious? so cheap? most of us i think bought at much higher price than this. Well,I did. And I like this amp alot. Lots of potential. Lots of mods to play around. Great amp. Check with the seller more about the amp before biding. =)

 

BUy buy buy! Join us,the 708B gang. Hahaha...

 

Thanks for your response. Really tempted by your advice especially about the potential but I not a DIY person and no electric/electronics/mechanics skills... never used a soldering iron, and furthermore the seller not responded yet. Will wait somemore and see how.

[edwinywh 0]

Thanks for your response. Really tempted by your advice especially about the potential but I not a DIY person and no electric/electronics/mechanics skills... never used a soldering iron, and furthermore the seller not responded yet. Will wait somemore and see how.

 

 

haha.... no worries,no soldering need for beginners. I din change and capacitors or any circuitry either.

Just buy some tubes and have fun!

 

If u searched around ebay,theres lots of GEMs tubes out there....

[Tristram 0]

haha.... no worries,no soldering need for beginners. I din change and capacitors or any circuitry either.

Just buy some tubes and have fun!

 

If u searched around ebay,theres lots of GEMs tubes out there....

 

 

Yes, u r right, I was looking at all those fabulous weird-looking tube amps by seller by nick of leshele. Some cost 1000s but open bidding from a few GBPs... U can take a look too, so many not heard of in this forum. Guess my next HK trip must go visit, but no address stated.

Edited September 15, 2006 by Tristram

[zhapchit 0]

i just found the ebay deal u mentioned. The shipping charges is quite expensive. You got to take note of that.