SimontY said:
Got it. I have not needed to work with BiPolars in the past, except at work
. There doesn't seem like a large amount of brands out there, but I am probably not really looking.I noticed that MunDorf now has some reasonably priced bipolars.
I am in the parts collecting phase of this, will be a few months.
Thanks,
Mike
Nothing Mundorf has, is ever reasonably priced. The non-polarized caps from PartsExpress are exactly, what you need. For values below 100 µF look for smooth-foil electrolytics, because they have less losses, thus better sound. Bigger values are usually rough-foil types.Tea-Bag said:
You can connect a small foil cap in parallel to the big electrolytics. That usually leads to better sound, but takes some experimenting to find the right match. Rule of thumb to start with is that the foil cap should have about 1 % of the electrolytic's value.
T-Bass for Full Range
Graham, I didn't read your posts closely enough about implementing this circuit with an FR driver and I sketched out what I thought was how you were recommending the circuit should look. Could you please take a look and critique?
T-Bass Full Range
I see now that you had recommended not using the series choke.
Erik
Graham, I didn't read your posts closely enough about implementing this circuit with an FR driver and I sketched out what I thought was how you were recommending the circuit should look. Could you please take a look and critique?
T-Bass Full Range
I see now that you had recommended not using the series choke.
Erik
Hi Freddi,
90Vct, 6.6A looks good to me. As long as the winding DCR is low (0.x Ohm) and there's enough inductance (more than 2 or 3 hundreds of mH), it'd be fine.
I'm using a 15V-0-15V on my center OB "sub", its inductance is more than 200mH (I don't remember the actual number). In the begining I somewhat worry about the low voltage rating. However it turned out working good.
The load impedance of the bass on my main baffle is 1 Ohm. My poor old Halfer deals with it properly, well, mostly. One thing happened the other day, I found the temperature on the heatsinks of both channels were quite different. Let it idle for quite a while, it's still the same.
So I re-adjusted the bias (turn down the warmer one), but the adjustment did not affect the temperature very much. I eventually turned the VR all the way down. It played some music under this situation for a while. Then I heard something abnormal -- some very little "clicks" were produced by the woofer of the channel I adjusted. And I saw the cone move slowly back and forth. Not very far, only within 1~2mm or so. And it moved faster in one direction and much slower in the other direction. The 'clicks' were simultaneous with the faster movement.
In spite of the little noise, the sound was normal. I didn't notice any ill effects. Is this you called "ratchet" ?
Later I turned the bias up a little, and it's gone. All things were back to the way they were.
As to my center OB sub, the parallel 2 woofers makes the impedance drop to 0.5 Ohm! The plate amp is working fine, with slightly wamer temperature on its heatsink, no big deal. And the sound is good, no noise, no abnormal cone motions. The plate amp was bought from PE many years ago, (maybe a Dayton). Rated 250W @ 4Ohm load, it's probably a discontinued item. I don't see it in PE site anymore.
90Vct, 6.6A looks good to me. As long as the winding DCR is low (0.x Ohm) and there's enough inductance (more than 2 or 3 hundreds of mH), it'd be fine.
I'm using a 15V-0-15V on my center OB "sub", its inductance is more than 200mH (I don't remember the actual number). In the begining I somewhat worry about the low voltage rating. However it turned out working good.
The load impedance of the bass on my main baffle is 1 Ohm. My poor old Halfer deals with it properly, well, mostly. One thing happened the other day, I found the temperature on the heatsinks of both channels were quite different. Let it idle for quite a while, it's still the same.
So I re-adjusted the bias (turn down the warmer one), but the adjustment did not affect the temperature very much. I eventually turned the VR all the way down. It played some music under this situation for a while. Then I heard something abnormal -- some very little "clicks" were produced by the woofer of the channel I adjusted. And I saw the cone move slowly back and forth. Not very far, only within 1~2mm or so. And it moved faster in one direction and much slower in the other direction. The 'clicks' were simultaneous with the faster movement.
In spite of the little noise, the sound was normal. I didn't notice any ill effects. Is this you called "ratchet" ?
Later I turned the bias up a little, and it's gone. All things were back to the way they were.
As to my center OB sub, the parallel 2 woofers makes the impedance drop to 0.5 Ohm! The plate amp is working fine, with slightly wamer temperature on its heatsink, no big deal. And the sound is good, no noise, no abnormal cone motions. The plate amp was bought from PE many years ago, (maybe a Dayton). Rated 250W @ 4Ohm load, it's probably a discontinued item. I don't see it in PE site anymore.
hi CLS -- when my Samson F1200 "ratcheted"- there were very loud tweeter threatening "clicks" - input Z dipped to about 2.3 ohms IIRC with 20mH and 500uF - I also think my Erse coil may have been getting into saturation (?) my 12" Karlson played >10dB louder than a Madison X21 - - re: T-bass - not many amps seem to be designed to work into 1ohm - - can that affect the output's MTBF?. (I;'ve had DH200/500 and Xl280) From what I could tell the simple LC "boost" circuit added an order to LF slope and usally gave ~6-7d|B bump-up . Maybe the toroid's seller can give dcr figures. How's your guitar midrange playing now? Best wishes, Freddy
I think the biggest risk on the power amp would be overheated (by the extra current). So if only the temperature is kept under a resonable range, I don't worry too much.
On the other hand, maybe my usage is far far quieter than most. In such a small apartment and 4 x 18", I really don't need very much power. So the actual loads of my amps should be not that tough. ( Maybe I'll find a chance to let them stretch their legs to see if any possible trouble. )
And, my system is 2 way active, so if the bass amps go into trouble, they won't touch the fragile mid-high.
My 12" guitar mids are singing very well, I have zero complaint
On the other hand, maybe my usage is far far quieter than most. In such a small apartment and 4 x 18", I really don't need very much power. So the actual loads of my amps should be not that tough. ( Maybe I'll find a chance to let them stretch their legs to see if any possible trouble. )
And, my system is 2 way active, so if the bass amps go into trouble, they won't touch the fragile mid-high.
My 12" guitar mids are singing very well, I have zero complaint
just to see what things might happen - I push the big odaiko drum whacks pretty loud - felt like my couch shook with 18" Karlson and 300 watt peak (spl read around 115dB at the couch and cone movement ~3/16" p-p) - or 150 watt/channel tube amp with K-horns . Did others in the guitar speaker mid thread find off-shelf guitar 12" which play well without much mods? I picked up a few old 12" with whizzer which are kinda like guitar speakers - Q's in the 0.73 region and fs maybe around 90
LC "boost"
LC "boost"
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Transformer Hookup Help
Graham or anyone that has installed a T-Bass circuit -
Just received my Avel transformers and I would like to clarify how to hook it up. I have this transformer:
http://www.parts-express.com/pe/pshowdetl.cfm?&DID=7&Partnumber=122-630&ctab=1#Tabs
According to one of Grahams posts of the t-bass circuit, on the positive input the line from the amp is hooked to the 12v tap. 0v tap goes to the minus speaker input and the 24v tap goes to the plus speaker.
My transformer is a 250v - 30v/30v. There are 2 0v lines and 2 30v lines. What would be considered the 12v (or 15v) input?
I can provide more information on the transformer if necessary.
Graham or anyone that has installed a T-Bass circuit -
Just received my Avel transformers and I would like to clarify how to hook it up. I have this transformer:
http://www.parts-express.com/pe/pshowdetl.cfm?&DID=7&Partnumber=122-630&ctab=1#Tabs
According to one of Grahams posts of the t-bass circuit, on the positive input the line from the amp is hooked to the 12v tap. 0v tap goes to the minus speaker input and the 24v tap goes to the plus speaker.
My transformer is a 250v - 30v/30v. There are 2 0v lines and 2 30v lines. What would be considered the 12v (or 15v) input?
I can provide more information on the transformer if necessary.
Still not understanding the information on the transformer. Here is the diagram on the side.
250va
blue----------- I -----------Black 0v
gray----------- I -----------Red 30v 4.17a
2 x 115v
violet-----------I-----------orange 0v
brown----------I-----------yellow 30v 4.17a
So, am I to assume that I can use the orange in to the transformer -- red down to the minus of the driver and yellow to the plus of the driver?
John
250va
blue----------- I -----------Black 0v
gray----------- I -----------Red 30v 4.17a
2 x 115v
violet-----------I-----------orange 0v
brown----------I-----------yellow 30v 4.17a
So, am I to assume that I can use the orange in to the transformer -- red down to the minus of the driver and yellow to the plus of the driver?
John
Tie the red and orange together, so you'll have:
Black: 0V
R+O: 30V
Yellow: 60V
There you go.
And for those wires for mains (blue, gray, violet, brown), if any conductors exposed out of the shield, cut and wrap them well with heat shrink tubes or simply by PVC tape. Do not short any of them. Those unused windings should be kept open.
Black: 0V
R+O: 30V
Yellow: 60V
There you go.
And for those wires for mains (blue, gray, violet, brown), if any conductors exposed out of the shield, cut and wrap them well with heat shrink tubes or simply by PVC tape. Do not short any of them. Those unused windings should be kept open.
You're welcome.
----------------------------
Say, I got an idea for those who worry about the ultra low impedance.
How about adding another transformer in front of the whole T-bass: now it's step down. So the amp sees normal (and flattened) impedance and let the T-bass do the 'tuning'.
This might be a good thing for those "high power" amps which have large voltage swing (to spare) while might be limited in the current output.
The only possible draw back I can think of would be some more loss by this insertion. And of course the extra cost
Any comments?
----------------------------
Say, I got an idea for those who worry about the ultra low impedance.
How about adding another transformer in front of the whole T-bass: now it's step down. So the amp sees normal (and flattened) impedance and let the T-bass do the 'tuning'.
This might be a good thing for those "high power" amps which have large voltage swing (to spare) while might be limited in the current output.
The only possible draw back I can think of would be some more loss by this insertion. And of course the extra cost
Any comments?