• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Would an s5 K-12M kit suffice?

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#21
edjosh23 said:
Ooo, I like the mag 1515, the THD is a lot less than what was showing up with the universal amp. I saw an article when reading tubez for noobz, about a Magnovox amp. .
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It is a bit of a strange circuit, but well respected.

What about the tube upgrade? Sovtek EL84M
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I wouldn't bother. You can always get some later, or get some NOS or even used EL84 that are better -- even better if they are cryo-treated.

I've done some research on the Wave 8's, which look really nice, and inexpensive enough to where I could build those and myabe a preamp, but they have been discontinued, and I like the idea of almost 2 times as much power for my new speakers.
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been replaced by an AV20 hasen't it?

I know where a pr of new WAVE 8s are sitting waiting to be sold 🙂

dave
 
#22
leadbelly said:
Dave, what would be a comparable scratchbuild design? I would like something that used all Hammond xfrmr's, easy to source and get a good price around here.
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Single ended or PP? You could certianly put together a Mulligan (my buddies eveoZens are pretty sweet if low on power), or nn SE EL34 -- maybe even parafeed. The 125 family of iron is fairly decent, cheap, and versatile.

PP might be a bit more of a challenge. One thing you might want to explore -- there should be lots of old Dyna ST70s or SCA35 in cow town (last time i was there picked up an FM3 for a $1 at a garage sale ")) to use as donors (Pilot, Scott, Fisher, Lafayetter too)

I'm partial to EL84s my self.

dave
 
#23
planet10 said:
One thing you might want to explore -- there should be lots of old Dyna ST70s or SCA35 in cow town (last time i was there picked up an FM3 for a $1 at a garage sale ")) to use as donors (Pilot, Scott, Fisher, Lafayetter too)
dave
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You will always be the master of garage sales, I could never hope to even be in the same category (not to mention thrift stores). But I will have to take even a quick look around.
 
#24
Bottlehead or Decware

If you had more sensitive speakers I would suggest looking at the Bottlehead website or Decware site if you have not already, especially if you are interested in DIY. Their kits seem like very good values and well respected both for sonic quality and the parts composing their kits, although both are low powered, about 2 watts and only suitable for higher efficiency speakers.
 
#25
Yea its the AV20, they are like $250,

is the Mag 1515 point to point or PCB? Do you know by anychance know about any instructions or if jusch a schematic comes with it. A did a search for the amp, but came up with nothing. Do you know what the real name of the Magnovox is? Any mods you know of?

Thanks,

How much is this mystery pair of Wave8s? (just curious)

Thanks,

Josh
 
#26
edjosh23 said:
is the Mag 1515 point to point or PCB? Do you know by anychance know about any instructions or if jusch a schematic comes with it. A did a search for the amp, but came up with nothing. Do you know what the real name of the Magnovox is? Any mods you know of?
Click to expand...

email Gabe. The real name of Magnavox is -- Magnavox.

How much is this mystery pair of Wave8s?
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Don... 250 595 HiFi (i can send you an email too)

dave
 
#28
edjosh23 said:
two people want me to build them tube guitar amps, could wave 8s be a possible alternative for them?
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Not really, the Wave 8's are plain power amps, which is a LONG way away from a guitar amp, which really needs a good preamp that has tone and presence controls and can overdrive the power stage. I doubt any capable guitarist would put up with the lack of flexibility for a significant time.
 
#32
well, the Mag-1515 would be about $550

but what about diyhifisupply? here is the EL34 kit is about $600 and 40watts.

I'm planning on ordering the PEC pot in the group buy (the upgrade pot in the kit) I can also get the driver tubes and pre-amp tubes for pretty cheap too (2 x 6922 and 2 x 6SN7)

The power tubes prices are a little different, the EL34s are cheaper from diyhifisupply

The 6550s and the KT88s I found cheaper, but again the Valve Art might be better than the cheap ones that I have found.

Also, not sure if I'm willing to go that high ($700)

What do you all think about this amp kit?

Thanks,

Josh
 
#33
edjosh23 said:
but what about diyhifisupply?
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Brian Cherry's amps are very good value... North American supplier is Kevein Haskins at diycable.

I understand that this is to be available p-p. At 40 W it is probably fixed bias (my preference for AB is cathode bias). Best is when you mod to Class A and add a CCS on the cathodes (you'll get about 10W)*

It comes down to whether you want EL84s or EL34s. EL84s are pretty sweet.

*(notice the trend -- the less power the amp puts out the better, in general, the amp sounds)

dave

(At the rate you are going, you are going to be dropping a grand on an amp -- there is a lot to be said about starting out modest, poking around some, and learning where you really want to go)
 
#34
DiyCable has had almost nothing for a month now, when it comes to tubes, here is the page

EL38 and EL84s aren't interchangable are they?

So you recommend a SE amp with about 10watts?

I worked as a mechanic last summer, its up to me how much money I want to spend, I made quite a bit.

Any other place for Brian Cherry's amp?

add a CCS? (I still have to refer back to a noob page, I don't have all the definitions down)

Thanks,

Josh
 
#36
edjosh23 said:
add a CCS? (I still have to refer back to a noob page, I don't have all the definitions down)
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A CCS is a constant current sink (or source). It is a circuit commonly made with transistors, which is designed to 'pull' or 'push' a pre-programmed amount of current out of or into whatever is connected to it.

Connecting a CCS at the cathodes of a push-pull output stage results in the limitation to class A only - good for linearity, bad for efficiency and output power. The sum of the currents through the output valves must be constant. Therefore, when one valve reaches cutoff (zero current) the other valve cannot continue increasing current conduciton (class B is avoided) and the output stage clips. Another, perhaps more subtle result of adding a CCS to the cathodes of the output stage, is that when one valve decreases conduction, the other must increase by exactly the same amount. This makes regulation of the power supply relatively important, since the current draw is constant, and provides good conditions for distortion cancellation in the output stage.
 
#38
edjosh23 said:
EL38 and EL84s aren't interchangable are they?
Click to expand...

You mean EL34, an EL38 is a different beast (i've only ever seen one mono amp with an EL38)

So you recommend a SE amp with about 10watts?
Click to expand...

If you are building a from scratch amp for the 1st time, i always recommend an SE amp because they are much simplier (like 5-7 parts per channel excluding the power supply) and easier to get the magic out of. A PP amp is trickier. A kit gives you more chance of success -- if on a board less room for tweakage.

Any other place for Brian Cherry's amp?
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If Kevin can't supply, i wouldn't hesitate to buy from Brian in Hong Kong. He is a Canadian (from Toronto i believe, but with family just up the island from me).

add a CCS? (I still have to refer back to a noob page, I don't have all the definitions down)
Click to expand...

audiousername has covered this off nicely ... Allen Wright's amp of this configuration had a lot of died-in-the-wool SE guys rethinking things when they heard his 300B variation on this theme.

dave
 
#39
I think I might be able to handle the circuitry in a PP, or atleast I think so, circuitry building seems to me like just a lot of following directions/schematics. The inside picture of the ELLA on diyhifisupply looks somewhat confusing, but I think by not rushing and doing a lot of double checking it is feasable. (I'm not as cocky as I sound :angel: )

The spending money concept is: I'm willing to spend money on tubes, obviously they are important. One reason why I like kits is because of cases, being 17 with a dad that has no mechanical abilities limits me to my building skills. I see all of these beautiful amps, and think I could do something like that, but I dont think so.

All the tubes that I've heard are PP. My parents like music and good soundquality, but nothing more than Bose and Infinity. I was the first to introduce somewhat audiophile equipment into the house, but I want to try building different amps to see which I prefer the most, there is no better way then using the same speakers, listening in your room, and relaxing. The summer job gave me money to play around with, but by no means enough to really give me a good dip, or wash my face in. The Gainclone was a nice little dip, that I'm still waiting for the new pot, and I like the chip amps, but everyone loves TUBES. From what I understand is a SE amp would be best, but with my unefficient speakers power is such a big issue.

The Diyhifisupply Joplin is nice but seems a little expensive. You say the SE amps have few parts, with few parts I would be willing to maybe do something completely myself, but again I'm horrible with cases and would probably spend quite some money on the case. And i'd prefer atleast 10 watts so I can hear my speakers.

Are there any other good suggestions you all have?


Thanks,

Josh
 
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