Metropoulos Forum

I've been experimenting a little bit with different chokes in my builds. I know that Roe has done this a lot, so it would be interesting to get his comments. I haven't done a lot of comparisons before, so it was an interesting experience.

For this little shootout I had the following chokes on hand:

Metroamp 352-114 (Heyboer made). This is nominally 5H, don't know about the current rating.
M e r r e n C1999 clone. 3H, don't know the current rating, but should be average for a C1999.
M e r r e n 5H choke with increased current rating. This is important, as it will not drop as much in inductance when it saturates.
Heyboer HTS-8425 5H choke. This came from my Royal "Hiwatt" Jimmy Page amp. I don't know the other specs of this choke.

In other words, I had three 5H chokes and one 3H choke. I was surprised at the differences, even though they are spec-wise fairly close. According to most people, the Drake 352-114 choke used by Marshall from about 1965 through 1967 was a 3H choke. The Dagnall C1999 introduced late 1967 or early 1968 is by all accounts a 3H choke. I asked Chris M e r r e n about his opinion on the 352-114 - 3H or 5H - and he said this: "CHokes is a funny business....since the Henries measurement will change depending on how it is measured.....If the choke is measure with or without DC current and you need to consider the AC ripple also...since this will change the inductance value when measuring..." In other words, no conclusion...but he did wind me a 5H choke when I asked for one for a JTM45/100.
The 352-114 is wound on a paper bobbin, while the C1999 is wound on a plastic bobbin. Don't know if that changes the sound at all.

Now, for my observations. I compared the chokes in two amps, a late '67 style JMP50 build with both tube and solid state rectifier, and a JTM45/100.

JMP50:
I wound up liking the 3H C1999 the most, with the 352-114 second and the HTS-8425 the least. The C1999 had the most of that greasy and round distortion that I want, particularly from an EL34 amp, and especially from a 50-watter. Since my amp is kind of a hybrid of a late '67 and a mid-68 - filtering in solid state mode is more like a '68 - the C1999 is a good match. The 352-114 was just a touch "cleaner" sounding, particularly in the bass. The HTS-8425 was too stiff and clean and bright. I was surprised how far off from a classic Marshall crunch just that choke changed the amp. I didn't try the M e r r e n 5H in this amp as it was mounted on the 45/100 chassis.

JTM45/100:
The M e r r e n 5H choke sounded really good, but maybe a touch on the stiff side. Bass is really firm, but it's not overly bright. The 3H C1999 also sounded really good, but bass was looser and not as clean sounding, and the amp was more compressed all over. Not by a wide margin, but noticeably. The HTS-8425 was again my least favourite - somewhat sterile sounding. While I haven't done a shootout in the Hiwatt Jimmy Page amp yet, I suspect this choke works really well there and will stay in that amp. It only filters the screens on that design, BTW.

Funnily enough, I didn't notice any difference in ghosting between these choke, even though they did sound quite noticeably different. I am going to do some comparisons in my Black Flag JTM100 as well, which currently has a Metroamp 352-114. I suspect the 352-114 will end up in the JTM45/100, as it should be just the right mix between warmth and "grease" and compression at full tilt, while still remaining fairly clean sounding and not too loose in the bass.

Any other opinions on chokes?

After a bit of googling, I found out that HTS-8425 is Heyboer's stock name for the 352-114 clone they did for Metroamp. However, my two chokes did sound different...they also look slightly different. The one I got from Metroamp has two small ridges near the edge of the frame, whereas the one from my Royal Hiwatt Jimmy Page amp has a smooth frame. The Royal one also appears a little more stout.
IIRC, George had some NOS parts used in those chokes, is that correct? George, if you're reading this...was the 352-114 clone in your store exactly the same as Heyboer's HTS-8425, or a custom wind?

Good to see some research going on!

Some people say that the choke is like filter caps - it does a job and has no impact on tone. However in our type of guitar amps where the power supply is so reactive and part of the feel as much as the sound they are really important. I knew that the Heyboer was their version of the -114 so I was interested in your initial post .

Clips would be nice if you were a player who could bang out the same stuff time after time and not be influenced by the way the guitar and amp feel whilst you are playing but I am not sure if that would trnaslate into sound clips to demonstrate much of a difference.

My one experience of having to change the choke was my 45/100 EL34 clone (-132OT and -80PT) where I used a Drake choke from Carlsboro I had lying around - big mistake. I replaced it with one of George's -114s and it was transformed, much more like the original '67 it was based on.

I had hoped to do some similar experiments. I have a Marstran 20H RS type, a Metro -114 a Marstran C1999 and a MM 7H all for different JTM45s. The 20H should go in my coffin logo clone, the -114 in the '67 JTM50 clone, the C1999 in my 2204 clone and the MM 7H lives in my '66 JTM45 clone. Not sure if I have the time, so keep up the good work Shakti

I've tested the following:
Classictone 352-114 3H
Metro 352-114 5H
Marstran C1999 3H
Metro C1999 8H
(MM 7H used for a few things as well)
I've tested in 3 67 100w amps and a 68 12000 series, two of these ghosted slightly. Also, I compared the 114s in a 66 45/100.

Generally, higher inductance will minimize ghosting and give a tighter, crisper bass that sounds a little cleaner and more modern. sometimes it will feel stiffer as well. 3H will sound fatter and greazier, more like a real marshall - with a nice top end, much preferred for solos. 3H is good for blues, 7-10H for metal.

I pretty much use 3H in all my plexis, other values hardly sound right to me. I still have a 7h in my 45 and a 8h in my jmp50, but I will try 3H chokes there as well. Also, I use 20h (RS) in one of my 45/100 (it works well actually, being easier on the screens for one thing). In my 12000 series amp, the 8h sounded cool on the low end but I ended up with a marstran. the 5h sounds good if the primary impedance of the OT is way high.

I generally prefer the classictone choke but the marstran is also great. I actually a/b tested the classictone with an original dagnall in an original marshall that ghosted a little. the classictone ghosted less than the dagnall when running flat out and even sounded slightly better.

I do recall that my old ex-Black Flag Super Bass came with no choke (missing) when I bought it in person from ......eck, Music Ground.
By the time it was shipped via the sea to me, it had the funky totally inappropriate one that it is pictured with.
Having seen another Black Flag, this time a Super Lead, which I actually sold for them off their stand at the 1993 Chicago Vintage show, no commission of course, that's a whole different story. I know that Marshall started increasing it's filter capacitance in place of chokes and by the JCM or 2203 era, didn't they drop off the chokes altogether?
Mine was checked by a tech in Philly and it appeared to be the correct henry measurement, but it didn't feel that it was the correct type, being too modern.
Apologies for the highly technical discussion, but you know..I try!
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It is true that the power amp section is very critical in the earliest 100 watt Marshall's, with the transition from the JTM 45/100 to the steel chassis JTM's and on.
yngwie308

I went and checked the HTS-8425 vs the 352-114 in my JTM100 Black Flag clone, and could not hear a difference there...of course, my ears may have been biased now that I "know" they are the same choke...if they are. They measure almost exactly the same DC resistance as well - 106 ohm vs 108 ohm. Interestingly, I preferred these 5H chokes in the black flag over the 3H one - they seemed to "sing" a little better while still having classic Marshally crunch.

I'll have to go check the HTS-8425 in the JMP50 build again to see if my ears are playing tricks on me...but it looks like I'll end up with...

JTM45/100: 352-114 5H
JMP50 1986: C1999 3H
JTM100 Black Flag: 352-114 5H
JTM45 Bluesbreaker: HTS-8425 5H
Hiwatt Jimmy Page: M e r r e n 5H

I really preferred the classictone 3h in my dual rectifier amp, it sounds dirtier than george's 5h -114 (in a good way)

Put the 352-114 into my JTM45/100. I just love this choke in a 45/100 - seems to be a perfect fit. Sweet, singing tone with clarity at cleaner passages, and compresses beautifully right at the end at full volume. It also seems to give up the "Woman Tone" very readily, even better than the slightly bolder, stiffer feel of the M e r r e n choke I had in there before. That one too sounded really good, but it seemed to hold together "all the way" even with the amp at 10. Some people will probably like that better than the 352-114, but I like how it really starts to compress right at the end, gives it a lot of touch sensitivity.

The cab with Scumback M75-PVCs is starting to break in very nicely too. They were a touch stiff at the start, even with FBI, but sound better every day now. I'm running the JTM45/100 unattenuated into it. I quite agree, Roe...this combination gets awfully close to Clapton's tone in that classic clip where he demonstrates his wah sound.

BTW, the Metroamp 352-114 choke I have appears to be very, very similar to the HTS-8425. Only the bracket appears to be slightly different. In fact, the label on it says 352-114, HTS-8425 and finally a longer number...9xxxxxx or something like that. The one from my Hiwatt amp only says HTS-8425 and has a different 9xxxxxx number.

you guys ever compare chokes in general to not using a choke (traditional choke) instead using a 500 ohm high wattage resistor?

I have actually done that very thing in my Hiwatt Jimmy Page amp. I've put in a switch to select either a 5H choke or a 470R 10W resistor. The difference is really interesting - the resistor sounds cleaner, more "linear" and tighter. The choke is hairier, ballsier, dirtier, but makes things just a little bit more mushy. I prefer the resistor with a Strat and the choke with a Les Paul, but they are both valid and it's a nice feature to have it switchable.

BTW; I'm using the 3PDT switch that Valvestorm sells, and using two poles to do the switching (i.e. both insertion points for the choke/resistor). This switch is off in the middle position, i.e. in that position I will have infinite resistance on the screen supply. I've been switching it with the amp in standby just out of precaution, but would it be safe to switch it with the amp on? Remember that the output tube plates and the whole preamp, heaters and everything else except the screens will still be seeing full voltage while switching the screen supply.

thanks for responding on that one. I use the 500 ohm in some amps and a choke in others. Im blown away by the openess I get with just the 500 ohm res. Im not very good at the math, what does that eqaute to in henries if at all. . is there any corelation? example 500 ohms resistance =5h.. does it follow or go the other way say 300 ohm = 8H etc etc . or since its not an inductive choke the henries doent even come into play. so much I need to learn
. everything i do is by ear. I love the sag I get this way on my classic moder 100 watter. when it is u around 1 oclock its so addictive to play. the sag is so touch sensitive. it sounds both classic and modern at the same time. Yet on my other models im going to start using chokes again cause I want a stiffer feel. I had one guy retunr an amp saying why didnt you use a CORRECT choke. I said correct for what? its doing exactly what i want and exactly what the amp descripton said.

jerrydyer wrote:since its not an inductive choke the henries doent even come into play.

This. A resistor will not impede the flow in the same way that a coil will. Think of the properties of the capacitor, coil, and the resistor. If perfect in design (impossible btw) they will have none of the properties of the other. There will only ever be negligible side properties (although in larger caps and coils there will always be some resistive properties)

I bought some big chokes and have experimented with adding the choke before the OT like fender and vox did early on. this works particularly well on single ended amps and on amps that ghost with low filtering and that become too stiff with high filtering. If you have a dual rectifier amp that ghosts too much with stock filtering, and increased filtering destroys the tone and response, then a 3h 500ma 36ohm hammond 193 choke works well. the voltages will drop a little and the tone will be slightly cleaner and smoother. you maintain the amps basic voice but get rid of ghosting. also a big choke before OT can tighten the bass on small amps with tube rectifier (e.g. 5e3).

You made me consider getting a 3H choke for my 12xxx. But shipping to EU is almost fifty bucks....

Roe wrote:I've tested the following:
Classictone 352-114 3H
Metro 352-114 5H
Marstran C1999 3H
Metro C1999 8H
(MM 7H used for a few things as well)
I've tested in 3 67 100w amps and a 68 12000 series, two of these ghosted slightly. Also, I compared the 114s in a 66 45/100.

Generally, higher inductance will minimize ghosting and give a tighter, crisper bass that sounds a little cleaner and more modern. sometimes it will feel stiffer as well. 3H will sound fatter and greazier, more like a real marshall - with a nice top end, much preferred for solos. 3H is good for blues, 7-10H for metal.

I pretty much use 3H in all my plexis, other values hardly sound right to me. I still have a 7h in my 45 and a 8h in my jmp50, but I will try 3H chokes there as well. Also, I use 20h (RS) in one of my 45/100 (it works well actually, being easier on the screens for one thing). In my 12000 series amp, the 8h sounded cool on the low end but I ended up with a marstran. the 5h sounds good if the primary impedance of the OT is way high.

I generally prefer the classictone choke but the marstran is also great. I actually a/b tested the classictone with an original dagnall in an original marshall that ghosted a little. the classictone ghosted less than the dagnall when running flat out and even sounded slightly better.

What should be noted in this investigation, is the actually mA rating of the chokes, which will affect ghosting vastly. In the original 100 watt amps, the chokes were 100mA rated, which at full tilt, is running these beyond spec, hence the ghosting can be quite apparent.
According to specs, the Marstran C1999 choke is 150mA rated, and the ClassicTone equivalent 49-18058 is 250mA DC rated. This will have a massive bearing on ghosting and filtration. Equally as much as the actual inductance rating, since the originals often cannot cope with the task.