DIY Audio Projects Forum
 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

It is currently 06 Dec 2019, 00:15

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 64 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 7  Next
Author Message
PostPosted: 21 Jan 2009, 14:30 
Offline
User avatar

Joined: 04 Sep 2008, 09:35
Posts: 179
Location: Menton, France
Hi,
I Take it as i am adding this phono pre, i don't need this attenuator?
What i do need to know is how i add a headphone socket to this amp, one which of course cuts out the output via the speakers, when in use.

cheers


Top
 Profile  
 
PostPosted: 21 Jan 2009, 15:00 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 20:12
Posts: 972
Location: Houston, TX
You need some sort of attenuator somewhere. Be it a carbon pot, a stepped pot, a rotary switch tied to resistors, whatever, but you need something choke the signal a bit so that your amp doesnt blow your speakers into the next room. Does that phono pre have any mention of a pot on it? Probably it has somewhere to mount a pcb mount pot on it.
Ri

_________________
DIY Lightspeed Passive Attenuator


Top
 Profile  
 
PostPosted: 21 Jan 2009, 17:10 
Offline
User avatar

Joined: 04 Sep 2008, 09:35
Posts: 179
Location: Menton, France
Wow, sorry being a bit stupid in that last post!

yeah the pre does have a pot for the gain, which i'm going to leave, as i have some very old vinyl, that is not recorded at the same levels as modern vinyl, and thus will need a bit more umph. for the attenuator on the chipamp, i was gonna go the cheapy route and buy one. if this makes a big difference, then i'm gonna have to add it to my list!!!

just as a side, if you were to buy one which type would you go for?


Top
 Profile  
 
PostPosted: 21 Jan 2009, 19:50 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 20:12
Posts: 972
Location: Houston, TX
If I was going to buy a pot/attenuator?
Well, it would depend on my budget. There are some VERY nice relay switched pots out there with remote control for about $120. Frankly I bet that money is best spent there rather than on a stepped attenuator which I think is what most people would recommend. Dont get hung up on Alps pots. Everyone is mad about them, but I have not found them to be anything special. I prefer wirewound pots from the 50's, 60's, 70's. Old 'General Radio' pots sound nice in my chip system. Stepped attenuator would be next down on my list. So, it would go Relay/Remote, Wirewound, Stepped (but it has to be with decent resistors, no junkers), carbon pot. One thing about carbon pots is that the exact same part number will be 5-10k different in resistance in the exact same position as its matching pot. So with carbon pots I kind of think you need to do dual mono so you can dial in the stereo image correctly.
After all that, I still think the Lightspeed Attenuator is the cat's a$$. Really nice clear and smooth sound. However, it is a costly little bugger. The resistors cost about $3 each and you have to buy probably 15-25 to get 4 good matches. You have to test them and compare their resistance in several steps. It took me a few days to do. I could have done it faster and maybe knocked it out in a day but anyway. So the nice thing is that after buying 25, one dying, and using 4 now I have 20 left and a few matches left. If I want to build another I maybe only buy 8 more and probably will get several more matching pairs out of that when compared against my remaining 20.

Neat site I found: DIYCLUB
They have the relay remote Regular pot with remote that says Alps but that ends up being Alps OR Panasonic AND

Or just go to ebay and get a stepped attenuator or wirewound pot but look for Log style or Audio. Both mean same thing but the linear pots will be fine except that when you turn the volume up it wont increase the way you expect it to.
Ri

_________________
DIY Lightspeed Passive Attenuator


Top
 Profile  
 
PostPosted: 22 Jan 2009, 16:06 
Offline
User avatar

Joined: 04 Sep 2008, 09:35
Posts: 179
Location: Menton, France
hi RI

Found this, Quick huh? what do you think
http://cgi.ebay.fr/VISHAY-SPECTROL-MODE ... .m63.l1177


Top
 Profile  
 
PostPosted: 23 Jan 2009, 08:03 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 20:12
Posts: 972
Location: Houston, TX
The pot will probably be fine as long as its the right rating. I have used 2 different wirewound pots and liked them both very much. But you know they made a lot of them back then and I am sure there are some bad ones as well. I used General Radio pots and Helipots but I am sure Vishay made good ones to.
The .2mm 31AWG wire you have will not be any good for power. It will probably just fry right there. It may work for the signal but worries me. My CD player outputs .2amps and this is twice the power handling of that wire. So thats why I suggest to twist a few of them together and then use that as one wire in the signal.
The pic you posted of your board... The wire it asks for over on the right side of your pic needs to be 20AWG or larger. The signal wire which is the few wires they call for on the left side of your pic can be a few of your 31AWG twisted together to make one wire.
The 'jumpers' are the wires that are on the board from one point to another point. They "jump" over traces that could not be routed around. So the wires you first asked about are called 'jumpers'.
Ri

_________________
DIY Lightspeed Passive Attenuator


Top
 Profile  
 
PostPosted: 24 Jan 2009, 14:33 
Offline

Joined: 07 Jan 2009, 00:42
Posts: 20
Question on pots as well, has anyone used or know about Bomar?


Top
 Profile  
 
PostPosted: 24 Jan 2009, 16:03 
Offline

Joined: 07 Jan 2009, 00:42
Posts: 20
sorry for the double post but.

Antek sent me a the wrong tranfo, they sent a 400VA 23VAC, not the 300VA 25VAC. Before I go about returning it, I had another few developments go on in the speaker front.

I found a decent set of bookshelf speakers on amazon. Ordered them, turns out they didn't stock them anymore. Looked around and now I acquired a set of Polk Monitor 50s for a decent price. The speakers are bi-ampable so the question is, would it be possible to run 4 channels off the single 400VA 2 tweeters, 2 mid-range? or should I just do 23VAC into 2 channels and build a crossover (if needed)?


Top
 Profile  
 
PostPosted: 24 Jan 2009, 19:27 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 20:12
Posts: 972
Location: Houston, TX
Not I.
Ri

_________________
DIY Lightspeed Passive Attenuator


Top
 Profile  
 
PostPosted: 24 Jan 2009, 20:10 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4580
Location: Winnipeg, CANADA
megamahi wrote:
Antek sent me a the wrong tranfo, they sent a 400VA 23VAC, not the 300VA 25VAC. Before I go about returning it, I had another few developments go on in the speaker front.

I found a decent set of bookshelf speakers on amazon. Ordered them, turns out they didn't stock them anymore. Looked around and now I acquired a set of Polk Monitor 50s for a decent price. The speakers are bi-ampable so the question is, would it be possible to run 4 channels off the single 400VA 2 tweeters, 2 mid-range? or should I just do 23VAC into 2 channels and build a crossover (if needed)?

100VA per channel is a little on the low side, but I have used as low at 80VA without any noticeable problems. Can you post some more details about the speakers. Are yo sure there is no internal XO?
Cheers

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 64 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 7  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
DIY Tube Projects :: DIY Tube Amp Kits :: DIY Speaker Projects :: DIY Solid State Projects :: DIY IC / Op-amp Projects :: DIY Phono Projects :: DIY Cable Projects :: Hi-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy