It is currently Mon Mar 16, 2020 2:56 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 302 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 21  Next
Go to page Previous  1, 2, 3, 4, 5 ... 21  Next
Author Message
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Sun Feb 24, 2013 2:15 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Tue Mar 01, 2011 3:10 pm
Posts: 5646
Location: Gateway to the West
stratele52 wrote:
Thank's T2Stratman,

Do you think I should stay there 2 days? Enough stock to see ?


Yes, more than enough aircraft to see. And talk to the guys running some of the displays, they have some great stories of missions they flew in some of those aircraft!

T2

_________________
-----------------------------------------------------------
What time is it? It's Fender Time.


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Sun Feb 24, 2013 2:25 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
T2Stratman wrote:
stratele52 wrote:
Thank's T2Stratman,

Do you think I should stay there 2 days? Enough stock to see ?


Yes, more than enough aircraft to see. And talk to the guys running some of the displays, they have some great stories of missions they flew in some of those aircraft!

T2


Thank's I'll book to stay 2 days.


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Sun Feb 24, 2013 3:08 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
63supro wrote:
Looks like it's gonna be a fun build Bill.


Yes, I think it will be. :D

_________________
Bill

Image


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Sun Feb 24, 2013 11:14 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Tue Apr 07, 2009 7:05 pm
Posts: 2333
Thanks for this, Bill. I much appreciate the willingness to explain the work as you go and teach some of us a few things. Documenting work such as this is more time consuming than people tend to realize.

Best of luck with the surgery and here's to a speedy recovery!


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Mon Feb 25, 2013 3:57 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
Toronado wrote:
Thanks for this, Bill. I much appreciate the willingness to explain the work as you go and teach some of us a few things. Documenting work such as this is more time consuming than people tend to realize.

Best of luck with the surgery and here's to a speedy recovery!


Thanks on all counts. :D

_________________
Bill

Image


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Mon Feb 25, 2013 4:26 pm
Offline
Amateur
Amateur
User avatar

Joined: Thu Dec 29, 2011 11:46 am
Posts: 190
Location: Coupeville, WA
Bill, you will not be disappointed with the trainwreck...somewhere in this crypt (moved recently) i have data on the A0 and A1 builds ...i tried using the unused triode as a cathode follower, i tried 3 variations of both DC and ac coupled circuits..the data is here somewhere something to consider...an unused triode...a terrible thing to waste.

i have really nice amps...but the trainwreck clones are my most played amps (they are cathode biased) A0 based

enjoy the build i will lurk...

hope the surgery went well/goes well

trick for counteracting pain pill side effects...stool softener :shock: ...outta here

my bro went though all that Achilles x2 the 2nd time he listened to the doc...
take care

_________________
"It's not bragging if it's fact" - HABU_71


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Tue Feb 26, 2013 4:26 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Thu Oct 14, 2010 8:54 am
Posts: 1179
Location: Florida
Speaking of stool softener, Don't you have a stool that you can use at the workbench?

Hope the surgery goes well and we'll be waiting for your return. But hey! Take it easy!

Art


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Tue Feb 26, 2013 10:36 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
Art1 wrote:
Speaking of stool softener, Don't you have a stool that you can use at the workbench?

Hope the surgery goes well and we'll be waiting for your return. But hey! Take it easy!

Art


No, I've always preferred to stand while I work. I do have a secretaries' chair, and while it doesn't go high enough to sit on, it does go high enough to kneel on with one leg.

Thanks. I'll figure something out. I'll get pissed off if I don't. :lol: I'll be working from home starting on the 11th.

_________________
Bill

Image


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Wed Feb 27, 2013 11:14 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
Haven't had time to do any work on the amp, plus still waiting for a few parts that I forgot to order originally to arrive. Thought I would share a few thoughts I had on some tweaks I am considering for the amp.

The JAVA comes with PPI type master volume control. The real Express does not use a master, it is a straight high gain amp that most people play by setting the volume control at the "sweet spot" and then controlling the overall volume and drive with the guitar volume control. Although I know the amp will be loud as heck used this way, I can't bring myself to "pollute" the circuit with a master volume. If that means I can only play the amp during the day on Saturdays with the windows closed while wearing ear plugs, so be it. :lol:

The JAVA gives you the option of using the two halves of V1 as either a cathode follower to drive the tonestack or just 1/2 of V1 as a straight plate drive for the tonestack. The cathode follower half of V1 does not provide any gain and theoretically would make the amp a little more "touch sensitive". The 1 meg volume control would provide a pretty high load on the tonestack at max volume, decreasing as the volume is lowered. The tonestack of the 5F6A Bassman is driven by a cathode follower, but the stack then drives the phase inverter which provides a constant high load. Therefore I don't think a cathode follower driven tonestack in the JAVA would perform the same way that it does in a 5F6A. Since the Express uses a plate driven tonestack, I've decided to forgo the cathode follower option.

In a nod to cutting the gain of the amp a little bit, I'm thinking about adding a switch to one of the preamp tubes to disconnect the cathode resistor bypass cap and allowing the resulting negative feedback to cut the gain a little bit. The question is: which tube would give the best results? Logic would say to make the 25 mfd cap on V1A switchable since V1 has the greatest effect on tone and leave the 250 mfd cap on V2A fixed. When I have time, I'll do a gain calculation for both tubes. Any thoughts on using V1A vice V2A?

I'm planning on replacing the presence control of the JAVA with the modern Bassman Reissue circuit.

"Vintage" circuit:
Image

"Modern" circuit:
Image

The modern circuit has only a minor effect on presence control tone, but is quieter in operation compared to the vintage circuit which sounds "scratchy" as the control is turned due to the DC voltage present on the pot.

Finally, I've been comparing the frequency response of the JAVA tonestack to the Express A1a tonestack.

JAVA tonestack:
Image

Express tonestack:
Image

Although the two shapes are generally similar, moving the sliders shows that the Express tonestack provides much more bass cut and treble boost than the JAVA tonestack does. I'll probably go with the JAVA design and look at the effect of changing the s l o p e resistor value from 100K to 56K.

A few other tweaks I am thinking about but haven't decided upon yet are:

1. The Express uses three diodes for each half of the fullwave rectifier vice two diodes for each half of the JAVA fullwave rectifier. Any advantage to useing two more diodes? I bought them, but there does not look to be room on the eyelet board to fit them in the circuit.

2. The Express power supply uses a total of 80 mfd for the first filter cap vice 100 mfd for the JAVA. I wasn't able to find suitable caps to make the Express circuit so I will keep the JAVA circuit.

3. The Express uses a 40 mfd cap for the second power supply filter cap vice 20 mfd for the JAVA. I purchased a 40 mfd cap, but I am wondering if there is any real advantage to using that value in the JAVA type power supply given the higher value for the first filter cap. Any thoughts on this?

4. I might make the negative feedback resistor switchable between two different values to provide different amounts of feedback and resulting loop gain.

That's about it for now. Much more to come. :D

_________________
Bill

Image


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Fri Mar 01, 2013 2:22 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
Hi Bill ,

Today is Friday, March the first

I hope the surgery went well and that you do not suffer too much.

Get Well before beginning the building of your new amplifier.

Louis


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Fri Mar 01, 2013 10:50 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Tue Jun 29, 2010 1:20 pm
Posts: 9640
Location: Indiana
bluesky636 wrote:
...
1. The Express uses three diodes for each half of the fullwave rectifier vice two diodes for each half of the JAVA fullwave rectifier. Any advantage to useing two more diodes? I bought them, but there does not look to be room on the eyelet board to fit them in the circuit.

The only advantage that I can think of is a higher PIV rating with more diodes, so better reliability.

2. The Express power supply uses a total of 80 mfd for the first filter cap vice 100 mfd for the JAVA. I wasn't able to find suitable caps to make the Express circuit so I will keep the JAVA circuit.

Really not a lot of difference. I would also opt for the 100 for a little better filtering.

3. The Express uses a 40 mfd cap for the second power supply filter cap vice 20 mfd for the JAVA. I purchased a 40 mfd cap, but I am wondering if there is any real advantage to using that value in the JAVA type power supply given the higher value for the first filter cap. Any thoughts on this?

IMO, this would make some noticeable difference, tighter bass response and less ripple (noise) when using twice the capacitance. I assume that this is the supply for the preamp/PI tubes? If you wanted a looser low end, go with the lower capacitance.

4. I might make the negative feedback resistor switchable between two different values to provide different amounts of feedback and resulting loop gain.

This I really like, and have wanted to try it myself. Is there also a cap in the feedback circuit? I would like to know what the difference is when switching the cap in or out of the circuit also. Maybe a small pot for the feedback resistor? Lower feedback resistor value, less (negative) feedback, more volume, more noise, but maybe a more desirable sound.....

_________________
---> "The amp should be SWITCHED OFF AND UNPLUGGED before you do this!" <---

Por favor, disculpe mi español, no se llega a la práctica con mucha frecuencia.


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Sun Mar 03, 2013 8:11 am
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
stratele52 wrote:
Hi Bill ,

Today is Friday, March the first

I hope the surgery went well and that you do not suffer too much.

Get Well before beginning the building of your new amplifier.

Louis


Came home from the hospital yesterday. All went well. The damage to the tendon was quite extensive, to the point that blood was no longer getting to it and the tendon tissue was dying. My doctor removed the damaged tendon, replaced it with another one from elsewhere in my foot, lengthened the achilles tendon, moved the heel over by 1 cm and a few other things. He showed me some neat photos he took of the tendon before removal and of the titanium brace the holds the heel together. He promised to e-mail them to me.

The pain is moderate but I have some good meds. I need to keep the foot elevated so it may be a while before I can work on the amp. Moving around from room to room and up/down stairs is tricky.

_________________
Bill

Image


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Sun Mar 03, 2013 8:17 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
Glad to hear that everything went well. Take care of yourself.


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Sun Mar 03, 2013 8:23 am
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
shimmilou wrote:
bluesky636 wrote:
...
1. The Express uses three diodes for each half of the fullwave rectifier vice two diodes for each half of the JAVA fullwave rectifier. Any advantage to useing two more diodes? I bought them, but there does not look to be room on the eyelet board to fit them in the circuit.

The only advantage that I can think of is a higher PIV rating with more diodes, so better reliability.

Good point. Hadn't thought about that. Not sure if there is room for the extra two diodes.

2. The Express power supply uses a total of 80 mfd for the first filter cap vice 100 mfd for the JAVA. I wasn't able to find suitable caps to make the Express circuit so I will keep the JAVA circuit.

Really not a lot of difference. I would also opt for the 100 for a little better filtering.

Yeah. Besides, all those caps look pretty cool in there. :lol:

3. The Express uses a 40 mfd cap for the second power supply filter cap vice 20 mfd for the JAVA. I purchased a 40 mfd cap, but I am wondering if there is any real advantage to using that value in the JAVA type power supply given the higher value for the first filter cap. Any thoughts on this?

IMO, this would make some noticeable difference, tighter bass response and less ripple (noise) when using twice the capacitance. I assume that this is the supply for the preamp/PI tubes? If you wanted a looser low end, go with the lower capacitance.

Actually, the 40 mfd cap is the filter for the power tube screen voltage supply.

4. I might make the negative feedback resistor switchable between two different values to provide different amounts of feedback and resulting loop gain.

This I really like, and have wanted to try it myself. Is there also a cap in the feedback circuit? I would like to know what the difference is when switching the cap in or out of the circuit also. Maybe a small pot for the feedback resistor? Lower feedback resistor value, less (negative) feedback, more volume, more noise, but maybe a more desirable sound.....

The only cap in the feedback circuit is the presense control and like I said, I'll be using the "modern" configuration for that control. The feedback resistors used in the Express are typically 47K or 100K, so a 47K resistor with a 50K pot would be interesting. Not sure I would go with no feedack resistor as the Express is pretty high gain and no feedback may make it unstable.

_________________
Bill

Image


Top
Profile
Post subject: Re: New Amp Build - Trainwreck Express Clone
Posted: Sun Mar 03, 2013 8:24 am
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
stratele52 wrote:
Glad to hear that everything went well. Take care of yourself.


Thanks. I intend to. :D

_________________
Bill

Image


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 302 posts ]  Go to page Previous  1, 2, 3, 4, 5 ... 21  Next
Go to page Previous  1, 2, 3, 4, 5 ... 21  Next

All times are UTC - 7 hours

Fender Play Winter Sale 2020

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

Search for:
Jump to: