First build in a while - a few questions

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2,550
I built a couple of amps about 10 years ago and am about to do another because I enjoyed it. My primary objective with this build is to experiment a bit with various well-known circuits - tone stack location (Fender vs. Marshall), fixed vs. cathode biased, push-pull vs. not. I'd like to experiment a bit with some different power tubes as well: primarily el84, 6V6 and (maybe el34, 6L6). To that end, some questions:

- I've got an option to buy one of a couple different retail amps at a decent price. I'm wondering whether to chase that and just mod them or to just buy the parts outright (thinking cost here). Just as a back-of-the-envelope calibration for me, what would you expect the parts (sans tubes and cabinet) to cost to build a push-pull amp based on 2 el84s and a marshall preamp (e.g. jcm/jtm) if I order them online? (Btw, I'm aware of several kits available to purchase. Most of them seem over-priced compared to sourcing parts myself. But, if that is not the case I might jump-start my project with one of them as a means of getting parts vs building exactly what their kits detail out.)

- Given my love for el34s it's conceivable that I'll convert the amp to use those (or maybe 6l6s) at some point. I'm guessing that this requires bigger transformers? True? If so, do these bigger transformers work equally well for the smaller tubes (e.g. el84, 6v6) so I can just use them for both (with good tone results of course)? Or, would I need to use smaller transformers for the smaller wattage amp for some reason?

- Does any of the affordable/free software on the market actually help with circuit design (ie. show issues/problems, etc.) vs. just facilitate drawing of the circuit?

Other thoughts welcome. Thanks!
-Gerald/banjoze
 

EADGBE

Member
Messages
12,337
If I was making an amp I think I'd go with two EL34s or two 6L6s. Along with four 12AX7s and a solid state rectifier. It would be a high gain pre-phase inverter master volume amp. Without an effects loop or reverb.

What type of amp are you planning on making?
 
Messages
2,550
If I was making an amp I think I'd go with two EL34s or two 6L6s. Along with four 12AX7s and a solid state rectifier. It would be a high gain pre-phase inverter master volume amp. Without an effects loop or reverb.
That's basically what I built last time.

What type of amp are you planning on making?
Similar to what I asked about above: a push-pull amp based on 2 el84s and a marshall preamp initially, but I'll probably experiment with the preamp quite a bit.
 

jthomas666

Member
Messages
898
There is a broad range of kit prices. In my opinion the Mojo and Victoria kits are pretty expensive. The Watts kits are in a middle range... and the Weber kits are less expensive and (in my opinion) a great value for the money. You can buy Chinese (I think) kits on ebay that are a little bit cheaper (no cabinet). One guy, on one of the forums I follow, built one of these and said it was ok, but I figure that it might be difficult to deal with an ebay seller if there was any problem.

I am currently building an amp and sourcing everything myself. Comparing the costs involved, I don't see much difference in price comparing the Weber kit to sourcing it myself. (No cab factored into that. I have had to go to several different companies to buy the parts that I want, and the shipping charges probably will add nearly $100 to the total cost.

If you plan on heavily modding the build, I would suggest that you buy a Weber kit that is close to what you want for your project. If that's a push-pull amp with the plan of using 6L6 tubes, maybe the 6A14HP (a Princeton map designed for 6L6s) or the 6A20 (blackface Deluxe) as the PTs should take el84s. The Weber site has the schematics, layouts, and parts lists for the kits which may be helpful for planning the mods to the tone stack and preamp. Weber has a history of willingness to sub out parts without a lot of hassle if you're going to be modding things. The 6A14HP kit is about $400 plus shipping without a cab and speaker which is about what my self-sourced build is costing without shipping.

If I were going to build a testbed for modding, I think that I would plan on building the eyelet board as 3 long turret board strips, instead of a standard eyelet board or turret board. That would make it easier to change out any wires running under the board. I saw that in a forum thread somewhere and it looked smart. I haven't tried that.

Edit- (like this)

1pt6qswxgn97.jpg


akoeu84po31s.jpg
 
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Messages
2,550
If you plan on heavily modding the build, I would suggest that you buy a Weber kit that is close to what you want for your project. If that's a push-pull amp with the plan of using 6L6 tubes, maybe the 6A14HP (a Princeton map designed for 6L6s) or the 6A20 (blackface Deluxe) as the PTs should take el84s. The Weber site has the schematics, layouts, and parts lists for the kits which may be helpful for planning the mods to the tone stack and preamp. Weber has a history of willingness to sub out parts without a lot of hassle if you're going to be modding things. The 6A14HP kit is about $400 plus shipping without a cab and speaker which is about what my self-sourced build is costing without shipping.
Super helpful link for me. Thanks!

If I were going to build a testbed for modding, I think that I would plan on building the eyelet board as 3 long turret board strips, instead of a standard eyelet board or turret board. That would make it easier to change out any wires running under the board. I saw that in a forum thread somewhere and it looked smart. I haven't tried that.
Cool idea. Does Weber sell those strips? I don't see them on their site anywhere.

Is there any particular part that come as part of their kits by default that you have found it worthwhile to upgrade to get better sound quality? I noticed that for some parts they offer different brands (e.g. transformers).
 

jthomas666

Member
Messages
898
Glad to help out. Here's a supply for the turret strips.

https://tubeamplifierparts.com/turr...ts-turret-strips/p/45615194/category=11811033

I am sure that you can find them elsewhere, but Ken Watts has a lot of good stuff. He sells several kits. I built the Supro clone and it is a nice amp. I have 2 Weber kit amps with the standard cheap Chinese transformers and they are fine. Every now and then on the Weber forum somebody has a bad one show up, but it's not common. Plus the Weber folks have been very good at replacing bad ones, even long after the amp was finished. I cannot guarantee that because I don't work for them, but you don't hear much ranting their customer service, once they get back to you.

People often use better jacks than what Weber supplies with their kits and sometimes pots. I think the standard pots and jacks are fine, but I don't play pro. The Weber wire is cloth covered and frays at the ends. I would change that out.

If this is your first build in awhile and you are going to be modding things, I'd go with cheap transformers and upgrade to something more expensive later when you have what you want finished. Better to accidentally burn up a cheap transformer. Part of what you will be doing in your planning process is to make sure that your PT has the current available to handle your full complement of tubes that you want in the final amp.. You may know how to do that, but if not, let me know and I'll post a link to the information that was supplied to me on the Weber forum.
 

swiveltung

Member
Messages
14,484
Cost wise you are better to find something to remodel. It's easy to put $500 in parts alone in a build.
Chassis $120
Transformers $150-175
Pots, resistors caps, knobs, sockets, jacks, switches, lights $200
Cab: $175
Speaker $90
Total: ~ $750
 

Tone_Terrific

Silver Supporting Member
Messages
36,585
I would get a chassis that can hold 4 power tubes and configure the sockets for 2 el84 and 2 el34 types to allow easy swapping, i.e. 2 parallel power stages but use only one pair at a time. Find xfmrs compatible with the most demanding config and use those.
 

makerdp

Member
Messages
624
If you want a very versatile "Marshall style" amp I highly suggest you head over to AX84.com and check out the "October Club" in the Associate Projects section. It's a 6V6 JTM-style that has a switch and variable negative feedback to give you more gain for a more "brown sound" as well. It is a very popular build there and sounds amazing. There is also a "stage" version that uses KT77 tubes for about 50 watts. It is very well documented and there is plenty of support available in their forums.

I would guess you would spend about $350 to $450 depending on transformer/chassis/component selection. Plus whatever speaker, cabinet, etc you choose.

I got into amp building because of cost too. I needed a new amp and could not afford what I wanted (Matchless DC30) so I built a clone from a kit for a fraction of the cost. I already had some electronics experience so it was an easy transition up to amp building. Then I got hooked... now I have a really nice collection of amps that if I bought all new or even used would have cost me a small fortune.
 




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