Ampeg V4.com

forum

You are not logged in.

#26 2010-10-22 08:22:19

hangman
Banned
From: Seattle Washington
Registered: 2006-09-04
Posts: 1848

Re: V4 midrange inductor

Looks cool David, its very much a v4 inspired design.
should have some kick!
you gotta keep us updated on this project.
I should have taken a photo of the inductor before I sent it out. sad
oh well, you should have it shortly. 
-steve

Offline

 

#27 2010-10-22 14:21:47

Casey4s
Member
Registered: 2010-09-26
Posts: 28

Re: V4 midrange inductor

Yes starting at the midrange (V4)it is all Ampeg up to the PI, the output is going to be a generic Fenderish design utilizing some NOS 5881s.

The active bass and treble baxandall is from the RCA manual.(V3)

The reverb is obviously pure Fender for simplicity.

The first stages (V1)are generic with mostly Marshall values for a more aggressive attitude.

There is an alternative input that has a BOOST stage (V2)that I am going to do a footswitch for.

I put two switchable rectifier choices, either a GZ37 or SS, and a switch to change from fixed bias to cathode bias.

This will take me all winter probably, but last year I got snowed in for 6 weeks, so this year I will have something to keep me busy.  LOL

I am also going to build a Walnut 1x12 combo cabinet for this (if it works).

Offline

 

#28 2010-10-22 14:35:06

Liquids
Member
From: CT
Registered: 2010-08-01
Posts: 491

Re: V4 midrange inductor

Cool design.  Nice way to put together what you like about different amps and roll it all together.  Especially neat that you aren't afraid of a more 'complex' design. Props to you!

If it's not too late, I'd note that while 5881s are a fine tube to like and use, make sure the PT (or filament transformer) and the socket spacing can handle the 1.6A type tubes, too.  Most tubes can handle whatever voltages you run the 5881s, but draw more heater current than the 5881, and since it's your design, you can design it how you wish!  Seems like not to long ago a 'real' current production 5881 was hard to find.  You never know what the tube market will be like in 30+ years! (gulp!)

Last edited by Liquids (2010-10-22 14:35:46)


Matthew

Offline

 

#29 2010-10-22 16:59:08

Casey4s
Member
Registered: 2010-09-26
Posts: 28

Re: V4 midrange inductor

I just checked my RCA manual and it says 0.9A per tube, the same as a 6L6GC. I have 7 pairs of NOS Tung-Sol 5881,s which are a 23 watt tube. I also have a couple of pairs of Phillips 6L6WGB's which are false 5881's, meaning they are 6L6GC's in a short bottle to meet Military specs, and are 30 watts like any other 6L6GC.

The next big challenge is drawing my build layout. I will need a couple of pots of coffee and a few straight hours.

EDIT:

30+ years?  LOL I am 63 years old now, I am not really concerned what happens after I am dead LOL LOL LOL LOL .....

Last edited by Casey4s (2010-10-22 17:02:24)

Offline

 

#30 2010-10-22 17:07:10

Casey4s
Member
Registered: 2010-09-26
Posts: 28

Re: V4 midrange inductor

This is my last Walnut cabinet, I am going to build another like this but about 6 inches wider to accomodate all these tubes etc.

http://i238.photobucket.com/albums/ff243/Casey4s/DIY%20BF%20Princeton%20Reverb%20Variation%20Walnut/b0cc.jpg

http://i238.photobucket.com/albums/ff243/Casey4s/DIY%20BF%20Princeton%20Reverb%20Variation%20Walnut/cf34.jpg

Offline

 

#31 2010-10-27 18:07:55

Casey4s
Member
Registered: 2010-09-26
Posts: 28

Re: V4 midrange inductor

I got the inductor today and I was surprised by it's construction and appearence.

The Inductor is mounted on a 1.25" square board with 4 terminal posts.  One cornre is cut off as a marker but I am still a bit stumped as to how the coil is distributed.

Which way does it count? Clockwise looking at the bottom?

Is the marker for pi #1 or is it ground?

Any help would be appreciated,

Tahnks

http://i238.photobucket.com/albums/ff243/Casey4s/AA%20Amp/001.jpg

http://i238.photobucket.com/albums/ff243/Casey4s/AA%20Amp/002.jpg

http://i238.photobucket.com/albums/ff243/Casey4s/AA%20Amp/006.jpg

Offline

 

#32 2010-12-19 15:37:56

Steelyman
VIP
From: Massachusetts
Registered: 2010-11-17
Posts: 107

Re: V4 midrange inductor

My 1st post - Hi all....

I have a midrange inductor from a SBT Solid-State Preamp Bass #8910000 which looks exactly like #8910001 in the V4 and has the same pinout. Does anyone know what the spec is for #8910000? - Thanks

Offline

 

#33 2010-12-19 19:46:14

Liquids
Member
From: CT
Registered: 2010-08-01
Posts: 491

Re: V4 midrange inductor

As steve/hangman has noted above, it should be an 800uH inductor with taps at 100uH and 300UH.  This schematic is of a V9 preamp with discrete inductors doing the same thing, and should make it clearer:

http://www.drtube.com/schematics/ampeg/v9pre-jp.gif


Matthew

Offline

 

#34 2010-12-20 00:04:47

Steelyman
VIP
From: Massachusetts
Registered: 2010-11-17
Posts: 107

Re: V4 midrange inductor

Ok, the V9 schematic shows inductor values in MICROHENRIES(uH) and everyone here is talking MILLIHENRIES(mH). Is the re-drawn V9 schematic incorrect? I think so.

As for inductor #8910000 I have from an old Ampeg SBT SS Bass amp, I'm reading values in  MILLIHENRIES (mH), I.E., ~800mH, ~300mH, and ~100mH with my inductance meter. Not in MICROHENRIES(uH) as shown in the V9 schematic. I'm hoping to use this part in an amp I'm building.

Offline

 

#35 2010-12-20 00:46:49

Mr.Ed203
New member
Registered: 2010-12-06
Posts: 8

Re: V4 midrange inductor

This forum is beyond great...more like unbeleivable.
Thank you so much guys!!

Offline

 

#36 2010-12-20 17:28:20

hangman
Banned
From: Seattle Washington
Registered: 2006-09-04
Posts: 1848

Re: V4 midrange inductor

steelyman,

yes that is right,  the ampeg inductors are all in millihenries.

casey4s,

didn't see your post from october,  if you still need to figure it out,  the ground tap and 800mh tap are the ones that only have one wire going to them.

my guess is that the Common is the tap that is marked.   
common meaning the tap that goes to the wiper of the mid pot.   

that should get you going

Offline

 

#37 2010-12-22 15:13:16

Liquids
Member
From: CT
Registered: 2010-08-01
Posts: 491

Re: V4 midrange inductor

Steelyman wrote:

Ok, the V9 schematic shows inductor values in MICROHENRIES(uH) and everyone here is talking MILLIHENRIES(mH). Is the re-drawn V9 schematic incorrect? I think so.

As for inductor #8910000 I have from an old Ampeg SBT SS Bass amp, I'm reading values in  MILLIHENRIES (mH), I.E., ~800mH, ~300mH, and ~100mH with my inductance meter. Not in MICROHENRIES(uH) as shown in the V9 schematic. I'm hoping to use this part in an amp I'm building.

Sorry. Piazza strikes again.  I didn't notice that.  but yeah, we are talking .8H .3H and .1H.

Now I have an idea why I could never use the discrete inductors I ordered from futurlec to get a breadboarded wah prototype to work right...  big_smile


Matthew

Offline

 

#38 2011-10-20 14:38:49

Steelyman
VIP
From: Massachusetts
Registered: 2010-11-17
Posts: 107

Re: V4 midrange inductor

I found these inductors on Fleabay....

http://www.ebay.com/itm/250796992219?_t … EBIDX%3AIT

They look to be fine for what I want to do, but they'd have to be experimented with.

Anyone know how the frequncy selections are calculated in the original V4 mid-select circuit with the components used?

I was thinking about adding more frequency points using a 6-pos rotary switch in my design. Anyone?

Last edited by Steelyman (2014-03-20 19:09:39)

Offline

 

#39 2011-10-20 14:46:33

Liquids
Member
From: CT
Registered: 2010-08-01
Posts: 491

Re: V4 midrange inductor

LTspice is the only way I'm aware of (and what I use)


Matthew

Offline

 

#40 2012-01-03 02:56:22

RP
New member
Registered: 2012-01-03
Posts: 1

Re: V4 midrange inductor

Hey Steve,

Is it possible for me to get another one of these inductors from you? I'm trying to build a single channel V4 clone with EL34's on the output and I would like to have one of these to see if there is any sonic difference between it and just some inductors in series.

This forum is a gold mine of information. Great work. Thanks.

Offline

 

#41 2012-01-04 03:51:26

hangman
Banned
From: Seattle Washington
Registered: 2006-09-04
Posts: 1848

Re: V4 midrange inductor

sent you an email. 

it is interesting to hear the difference between the toroidal inductors of the early v4s and the discrete ones of the mid-late 70s.   let us know your results.

Offline

 

#42 2012-03-04 20:35:42

hangman
Banned
From: Seattle Washington
Registered: 2006-09-04
Posts: 1848

Re: V4 midrange inductor

Steelyman wrote:

I found these inductors on Fleabay....

I was thinking about adding more frequency points using a 6-pos rotary switch in my design. Anyone?

That is exactly what SLM did when they made the SVT classic.   notice there are 5 positions on the reissue.

Offline

 

#43 2012-09-14 19:55:56

Jon K
Member
From: Norway
Registered: 2012-05-17
Posts: 14

Re: V4 midrange inductor

Does anyone know if the Mercury Magnetics V4 toroid choke will work in a V2 as well?

Offline

 

#44 2012-09-14 21:16:18

hangman
Banned
From: Seattle Washington
Registered: 2006-09-04
Posts: 1848

Re: V4 midrange inductor

The mercury magnetics one will indeed work in the v2.

But I don't really consider it an upgrade.  So unless yours is dead, I wouldn't pay the high price they are asking.

Offline

 

#45 2012-09-15 23:50:58

Jon K
Member
From: Norway
Registered: 2012-05-17
Posts: 14

Re: V4 midrange inductor

Good to know. The thing is that i'm building a V2 from scratch, so i dont have the choke at all yet. Exept from the one that is in my VT22. Is there any other place i might get one that's not "mercury priced" ? Thanks for the answer by the way! Saved me a lot of time.

Offline

 

#46 2014-03-29 22:29:53

Steelyman
VIP
From: Massachusetts
Registered: 2010-11-17
Posts: 107

Re: V4 midrange inductor

Hey all,

I really am stoked about finding a way to build a 6-way midrange selection circuit based on the Ampeg V-Series 3-way using these cheap 100mH inductors I got off ebay. The 1st thing I did was remove the stock Ampeg toroidal inductor from my V2 and take a few measurements with an inductance/DCR meter and what I found is a bit confusing. Check it out...

http://i292.photobucket.com/albums/mm31/Neal82852/AmpegV4_2013/Ampeg_V4_Inductor_Measurements.jpg

I would think that Pins 1 to 2 would be more than 100mH, and the same for Pins 2 to 3, which is only 50mH. Also, Pins 1 to 3 reads 300mH as does Pins 1 to 4. I have another toroid I recovered from a destroyed Ampeg SBT SS Bass Preamp head and got almost identical readings. Can anybody explain these numbers? It's almost as if the winding starts at Pin 1 with 3 wires and are all wound together at the same time, then 1 wire is terminated at Pin 2, another at Pin 3 and the last at Pin 4. The readings don't suggest taps off a single winding. I dunno.I need to think about this some more.....

http://www.youtube.com/watch?v=HY-03vYYAjA

Last edited by Steelyman (2014-03-29 22:57:34)

Offline

 

Board footer

Powered by PunBB
© Copyright 2002–2005 Rickard Andersson